CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

ANNUAL REPORT

2

1997

INTRODUCTION

5

Prestigious Highlights of 1997

6

Industrial Partners

7

Current Grants / Contracts

8

Current Research Topics

9

MOBILE COMMUNICATIONS RESEARCH GROUP

10

1. Satellite Mobile Communications

10

2. Broadband Satellite Communications

14

3. Terrestrial Mobile Communications

15

4. Wireless LAN

18

MULTIMEDIA SYSTEMS RESEARCH GROUP

19

1. Low Bit Rate Speech and Audio Coding

19

2. Image and Video Coding

20

3. Channel Coding

21

4. Modulation and Coding

22

COMMUNICATION NETWORKS RESEARCH GROUP

23

1. ATM and Broadband Communications

23

2. Network and Service Management

25

3. Network Access and Interworking

25

4. Internet and ATM over Satellites

26

CCSR STAFF

28

PhD’s awarded 95-97

30

CCSR PUBLICATIONS LIST

31

1997

31

1996

34

1995

38

INDEX

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

3

19

4

Centre for Communication Systems Research

INTRODUCTION The Centre for Communication Systems Research was set up as an autonomous Research Centre in 1996, within the School of Electronic Engineering, IT and Mathematics and now houses : ● 10 Academics ● 20 Research assistants ● 37 PhD Research students ● 6 Support staff Our research is sub-divided into three research areas as follows: Mobile Communications led by Dr Rahim Tafazolli Multimedia Systems led by Professor Ahmet Kondoz Communication Networks led by Dr Zhili Sun pending arrival of Professor George Pavlou in 1998.

Our research concentrates on future communication systems for the next millennium. We are unique in our coverage of: ● Mobile and wireless communications ● Satellite communication systems ● Integration of communication systems ● Telecommunication management systems (TMN, CORBA, Java)

In the UK, CCSR is a member of the two Virtual Centres of Excellence, in Mobile and Personal Communications and Multimedia Broadcasting. In addition we have major funding from EPSRC managed (ROPA, LINK, JREI) programmes and responsive mode Grants. On the industrial front, we now have twelve industrially-funded projects which cover UK, European, Japanese and US industries. CCSR is the UK’s largest and best known research centre covering Mobile and Satellite Communication Systems, Multimedia and Networking. On an annual basis we award several scholarships to study for a PhD and almost constantly have vacancies for Research Assistants to work on our various contracts. In addition to our research, CCSR is a major contributor to the Electronic Engineering School’s one-year Masters courses in Satellite Communication Engineering, Mobile and Satellite Systems and Telematics. We also contribute one-week courses to the continuing education programme in the areas of Satellite Communications, Mobile Communications and Telecommunications. We are progressively becoming more involved in technology transfer and consultancy to industry, by spinning off our intellectual property rights and technology and we are always willing to talk to potential collaborators.

INRTODUCTION

97

CCSR is a major player in the European Union, with fifteen ACTS and ESPRIT projects running from 1998. These range from satellite systems, mobile communications, multimedia, IP and ATM telecommunications management to new chips. Our European partners number around forty companies and universities.

This Annual Report gives a summary of our research as it was in 1997. Almost by definition things will have moved on by the time you are reading this and it is worth checking our Web pages for updates. (http://www.ee.surrey.ac.uk/CCSR/)

● Core network technologies (ATM, IP, Software telecommunications) ● Multimedia services and signals (speech, video and service) ● Networking (protocols, software, security) ● Enabling technologies (modulation, coding, signal processing, channel characterisation)

Overall, CCSR has over £4 million of ongoing specialised research, funded in approximately equal ratios from the European Union (ACTS, ESPRIT), the EPSRC (a major research council in the United Kingdom), and industry.

Professor Barry G Evans Director, CCSR December,1997 5

PRESTIGIOUS HIGHLIGHTS OF 1997 ● Presentation of the Queen’s Anniversary Prize for Higher and Further Education 1996 for “Excellence in Satellite Communications & Engineering - Research & Teaching”. ● Being the first UK university to become one of the four finalists for the Royal Academy of Engineering’s Premier MacRobert Award 1997 for Engineering Excellence in Satellite Communications and Engineering.

PRESTIGIOUS HIGHLIGHTS OF 1997

● Commencement of the Mobile VCE Programme with £0.75M award to Surrey, supporting 4 RAs, and 2 studentships over three years. ● Award of two EPSRC ROPA grants based on collaboration with industry and Surrey’s only special equipment grant for a Multimedia Performance Test Bed. ● Award of one of the first Space-Foresight contracts with Matra Marconi Space to study Air Interface Aspects of Multimedia Satellite Systems. ● Award of a Technology Transfer contract with Toshiba (Japan) for Speech Storage Technology.

ANNUAL REPORT 1997

● Involvement in sixteen bids for the EU third call for ACTS and the start of the first ESPRIT contract awarded with Siemens for ISDN chip architectures. ● Selected by the Cadence Group along with Berkeley, USA and Nan Yang University, Singapore in an International VCE for Communication Systems ● Appointment of new Racal Chair in Communication Network Management to Professor G Pavlou. ● Award of INMARSAT Chairman’s Prize to Dr Wei Zhao for work on “Terminal Location and Positioning in a Dynamic Satellite Constellation”, representing the most outstanding research in an area commensurate with INMARSAT’s business.

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CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

Industrial Partners ● VCE (Virtual Centre of Excellence) in: Mobile and Personal Communications: 5 Universities and 22 Industrial Companies Digital Broadcast and Multimedia Technology: 6 Universities and 12 Companies

● Laben Spa

● Acorn

● Matra Marconi Space (France)

● Airtel

● Matra Marconi Space (UK)

● Alcatel Espace

● Matsushita

● Alenia Spazio

● Mitsubishi

● Algotel

● Mobile Systems International

● Aurigae SA

● Motorola

● BBC

● NDS

● BT

● NERA

● Cadence Design Group

● Nokia

● Cable & Wireless

● Nortel

● CET

● Nova Telespazio

● CISCO

● NTT

● CNET France Telecom

● NTL Cable Telecoms

● CRL

● One2One

● CSELT

● Orange

● Cellnet

● Philips

● Dassault Electronique

● Quotient

● DLR

● Racal

● Dolphin Communications

● Roke Manor Research

● Ericsson

● Samsung

● Ericsson OMC

● Siemens AG

● European Partnership Contracts

● Simoco

● ACTS: SECOMS, SINUS, THESEUS

● Sintef T & I

● ESPRIT: COPARIS

● Société de la Bourse de Valeurs Mobilières de Bruxelles

● Fundacion Airtel ● Fujitsu ● Hitachi ● Hewlett Packard ● Hughes Network Systems ● IBM ● Italtel ● INMARSAT ● ICO Global

● Lucent Technologies ● L3S Conseil

INDUSTRIAL PARTNERS

● Société de la Bourse Français

● Space Bel ● Space Engineering Spa ● Space Helas ● Symbionics ● Telenor ● Texas Instruments ● TNO ● Toshiba ● Vodafone

● Intracom ● Iona Technologies 7

Current Grants/Contracts EPSRC

EUROPEAN

● Source and Channel Coding for Mobile Multimedia

● SECOMS-Satellite EHF Communications for Mobile Multimedia Services-EU ACTS 2

● Wireless ATM LAN

● SINUS-Satellite Integration into Network for UMTS-EU ACTS 2

● User Terminal Positioning in Non-GEO Satellite Systems ● Migration to 3rd Generation Personal Communication Systems

CURRENT GRANTS / CONTRACTS

● Variable Bit Rate Time Envelope Vocoder Using Source Dependent Rate Switching ● Study of Scintillation Applicable to Design of Satellite Communication Systems ● Global Integrated Personal Satellite Environment

● ACCORD-AdvanCed aCts brOadband joined tRials and Demonstrations-EU ACTS 3 ● SUMO-Satellite UMTS Multimedia service trials Over integrated Testbeds- EU ACTS 3 ● WISDOM-Wideband Satellite Demonstration Of Multimedia-EU ACTS 3 ● SORT-SOftware Radio Technology-EU ACTS 3

● Multimedia Testbed for Audio Visual Communications

● FlowThru ACTS 3

● Low Complexity Soft Decision Trellis Decoding of Block Codes

● IACI-Internet and ATM Convergence and Integration of Ipv6 with resource reservation of ATM

● Call Admission Control for Multimedia CDMA ● Multilayer Scaleable Audio & Speech Coding for 3rd Generation Systems ● GSM Network Optimisation

INDUSTRIAL ● Indoor Propagation Factors at 17-20 GHz and 60 GHz ● High Quality Speech Codecs for Premium Communications Services ● VCE in Mobile & Personal Communications ● Satellite Wideband Air-Interface Design (SWAID) ● Ad-Hoc Computer Networking ● Software Radio ● Indoor Propagation Measurements at 17 & 60 GHz

8

● ASSET-Advanced Satellite Switching End-end Trials-EU ACTS 3

● MIAMI-Management of the Information Infrastructure ● VITAL-Validation of Integrated Telecommunication Architectures for the Long-term ● REFORM-Resource and Fault restORation and Management close integration of control and management. ● COPARIS - Common Physical Access for ISDN Systems ● THESEUS - Terminal at High Speed for European Stock Exchange Users

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

Current Research Topics

● Terrestrial and Satellite Mobile Systems ● Narrow band and broad band systems

MULTIMEDIA & DSP ● Speech coding ● Joint speech and channel coding ● Image coding and compression

● Networking, services, terminals, antennas & propagation

● Error resilient coding for images

● Wireless LAN/cordless/mobile/satellite

● Performance analysis for speech and multimedia systems

● CDMA - Multi-user detectors, call admission control, power control, synchronisation, coded-CDMA, overlapped CDMA ● TDMA - equalisation ● Ad-hoc networking ● Genetic algorithm ● Integration cellular/cordless/ satellite systems ● Traffic modelling for multimedia

● RS/Trellis/Soft decoding and turbo coding ● Cryptography for Multimedia Communications ● Higher level modulation and joint modulation/coding ● DSP applications and implementations ● On-Board Satellite DSP and Processing

COMMUNICATION NETWORKS

● Integration cellular/cordless/ satellite systems

● Broadband service/traffic characterisation

● Packet communication in mobile networks - GPRS etc

● Performance assessment of Multimedia over ATM

● Band sharing CDMA/TDMA

● ATM over satellite and satellite networking

● Satellite constellation studies and QoS

● IP over GEO Satellite and LEO/MEO Satellite Constellations

● Mobile satellite - mobility management and neworking - resource management ● Satellite air-interface TDMA studies ● Mobile satellite channel modelling and simulators ● On-Board processing architectures

CURRENT RESEARCH TOPICS

MOBILE COMMUNICATION SYSTEMS

● Traffic management and congestion control in ATM ● Optimisation of TCP/IP over ATM ● Integrated services in INTERNE - Multimedia and Multicasting

● Broadband satellite - ATM/IP networking

● Network & Service Management using object, orientation, TMN and TINA

● Antennas - Intelligent base station and handhelds - Dual mode satellite/cellullar

● Multimedia service control using IN and TINA

● Propagation - Indoor up to 60 GHz, Satellite up to 30 GHz, macro + micro cells deterministic and physical statistical modelling, cell planning tools

● Future integrated Telecom Architectures ● Network security

● Intelligent micro/pico cells

9

MOBILE COMMUNICATIONS RESEARCH GROUP Aims

MOBILE COMMUNICATIONS RESEARCH GROUP

To research Global Universal Multimedia Personal Communication Systems integrated with cordless, cellular and satellite mobile components. To develop novel and practical techniques for the establishment and enhancement of personal communication networks and services for future public and private systems.

Achievements ● Breakthrough in Blind Search Algorithms-Genetic Algorithm

● Novel Mobility Management Technique for Satellite-PCS

● Fast, Adaptive, low complexity MultiUser Detector for CDMA

● Four Novel Multiple access protocols for integrated DATA+Voice in GSM/GPRS

● Fast, Frequency Planning Optimisation Algorithm

● New adaptive and predictive power control technique for CDMA

● Network Dimensioning Technique for Multimedia mobile Systems

● New call admission control for load balancing in CDMA

● Mobility Management Technique for Wireless ATM

● New mobile terminal positioning technique for satellite systems

● Novel Media Access Technique for Wireless ATM

● New in-call handover scheme between satellite and cellular systems

● Quality of Service Provisioning for Wireless ATM

● Full network integration between cordless and cellular systems

● Novel CDMA Multiple Access Scheme for UMTS

● Novel call-handling and routing in non-Geostationary satellite mobile systems

● New code Synchronisation and tracking Technique for packet CDMA

● Novel intelligent (terrestrial-satellite) mobile terminal antenna

● New Mobility Management Technique for GSM

● New physical statistical propagation models for terrestrial and satellite coverage prediction

● New Satellite Constellation Design ● New Handover for HCS algorithms

● High capacity indoor-outdoor radio architectures using intelligent antennas

Description 1

Satellite Mobile Communications

1.1 Network architecture and signalling investigation for GSM and satellite integration This work concerns research into the possibility of integrating GSM networks into dynamic constellation mobile satellite networks. The satellite constellation considered representative MEO (e.g., ICO), LEO (such as Iridium and Globalstar).

The work has been divided into several areas ● Design satellite radio link frame structure and logical channels ● Identify various inter-connection schemes between GSM network entities (MSC, VLR, HLR and GMSC) and satellite network entities (GMSSC, MSSC, LES and SVLR). The inter-connection reuses as much as possible of already existing GSM signalling interface (A, B, C, D, E and G interface). ● Design signalling procedures between dual-mode terminal and network (GSM or satellite) for various services in the integrated system. 10

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

1.2 Satellite Integration into Networks for UMTS Services

1.3 Non-GEO Mobility Management and Resource Management The aim of this work was to determine the optimum location area definition and size for a given S-PCN system that would produce the minimum mobility related signalling on the air interface. This involved analysing layer two paging and location update signalling. Key outcomes: 1

Intelligent Paging Strategies and new Location area definitions which result in minimisation of in-call handovers between FES (Gateways) and optimum call routing.

2

Handover solution between satellite and terrestrial cellular system. The techniques resulting from this work have been tested and optimised for ICO, Iridium and Globalstar Constellations.

1.4 S-PCN satellite availability in urban areas Satellite blockage caused by buildings will result in a loss of service from an S-PCN system. Some of the 1st generation systems employ satellite diversity to overcome blockage. To evaluate the behaviour of the two satellite channels fish eye images of typical urban areas were taken. The images were transformed to obtain shadowing statistics.

MOBILE COMMUNICATIONS RESEARCH GROUP

A laboratory test-bed has been set up for performance experiments in satellite-UMTS environment and the laboratory demonstration will be performed in the test-bed. Entities being produced in the project: S-UMTS dual-mode terminal, satellite FES, satellite constellation+satellite propagation channel emulator, terrestrial radio link simulator, fixed network (only a switch) and a test-bed controller.

1 Example urban fish eye image The fish-eye images can also reveal how similar the two satellite channels behave based on the elevation and azimuth angles difference between the two satellites.

11

The figures below show how the correlation of blockage coefficient varies with different satellite elevation and azimuth angle differences and how it can be predicted using a theoretical approach. 1.0 0.8

Correlation coefficient

MOBILE COMMUNICATIONS RESEARCH GROUP

0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 Sat. 30&30deg, w=dm/2=10m Sat. 30&45deg, w=dm/2=10m Sat. 30&30deg, dm=5m, w=15m Sat. 30&45deg, dm=5m, w=15m

-0.8

Azimuth Separation (degrees)

-1.0

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Azimuth Separation (degrees) Theoretical Prediction of Satellite Diversity Correlation The data from a large number of fish eye images have been applied to several 1st generation constellations to reveal statistics on, service availability, highest and second highest satellite visibility, and overall correlation of blockage between the two highest satellites in urban areas.

1.5 Non-GEO Stationary Satellite Constellation Design The aim of this work was to design a non-GEO satellite constellation as the satellite component of UMTS. Several demands and restrictions where initially placed on the constellation structure and coverage properties. Firstly to be competitive the orbit had to have fewer satellites than current 1st generation S-PCN proposals. At the time this limit was 66 satellites (Iridium). In order to minimise delay and power requirements the use of a LEO orbit was preferred, while avoiding the Van Allen radiation belts. In order to increase the availability of service and quality of service the constellation should provide dual satellite visibility at a minimum elevation angle of 15 degrees. The dual satellite diversity was restricted to the latitude range of +/- 70 degrees. The requirements from the constellation lead to the use of an inclined LEO orbit. An altitude of 1626km was selected. This orbit height provides a repetitive ground track by compensating the altitude to account for the precession of the Right Angle of the Ascending Node due to the earth bulge affect. An inclination angle of 54 degrees was found to provide a good trade off between double coverage at the equator and coverage at higher latitudes. The number of satellites used was 64. The satellites are arranged in 8 planes with 8 satellites in each. A phasing angle between each plane of 39.375 degrees resulted in the best dual satellite visibility. Given that the orbit provides continuous dual satellite visibility the constellation was called Deligo which is Latin for ‘I Choose’.

1.6 Band Sharing between Non-Geostationary Satellite-PCNs The first generation satellite PCNs are to operate at L-band for uplink and S-band for downlink to provide world wide services. However, the scarcity of free spectrum, together with the bandwidth requirements means that S-PCNs will have to share these bands with each other. In order to evaluate this complex sharing scenario, an Interference Simulation Program has been developed to model the dynamic satellite constellations (DSC) and to evaluate interference between such non-geostationary MSS and investigate techniques/criteria to make such bandsharing possible.

12

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

1.7 Multiple Access Schemes TDMA and CDMA and various hybrids are currently being investigated. Among these, the packet switched protocols for support of mixed services are also being investigated. We are also researching on the suitability of GPRS (General Packet Radio Services) and in particular the optimisation of the following schemes for packet S-PCN:

● Optimisation of frame structure for packet switching

● Error correction and re-transmission strategies ● Power control ● Random access protocol design

1.8 UMTS Satellite Channel Emulation Bringing together a number of the threads of the research is an EU ACTS project SINUS, which is investigating the air-interface of the satellite part of the UMTS as well as producing a demonstrator air-interface system and a satellite channel emulator. The latter is a project within Surrey and uses the channel data at L/S band from the propagation campaign that has been converted to models for any elevation angle and environment. Also built into the channel emulation are the orbit dynamics of LEO/MEO and the interface paths for satellites and mobile users from the system. The emulation will allow a simulation of any run for LEO/MEO/GEOs and allow the prototype air interface to be tested and evaluated.

1.9 Antennas and Propagation

1.9.1 Propagation Measurements and Analysis include: ● Satellite PCN measurements, narrow-band and wide-band at L,S,X bands simultaneously, forthcoming narrow-band at 20 and 30GHz. Measurements made in 5 environments and elevation angles from 30 to 80 degrees using helicopters. ● Physical-statistical models of Satellite PCN, providing attenuation statistics and time-series generation based on statistical measures of the building environment and deterministic knowledge of satellite constellations.

MOBILE COMMUNICATIONS RESEARCH GROUP

● Stand-by state (Handover, Diversity, synchronisation and time advance mechanisms)

● Analysis, simulation and modelling of scintillation effects for fixed satellite systems at 12.5, 20 and 30 GHz. Includes diurnal variations, time series generation and scintillation countermeasures using adaptive modulation schemes.

Physical-statistical model of mobile satellite propagation in built-up areas

13

1.9.2 Antennas:

MOBILE COMMUNICATIONS RESEARCH GROUP

● Design of Wire quadrifilar helix antennas. Compact fractional-turn designs for S-PCN handsets. ● Printed quadrifilar helix antennas for easy manufacture, small size and robustness. Analysis package created using Integral Equation / Method of Moments. ● Intelligent handset antennas for multiband, multimode operation in terrestrial and satellite systems. Incorporates adaptive matching and polarisation and pattern diversity. Such antennas are a key component of future software radio technology.

● Noise calculations for satellite PCN hand sets. Includes the effects of sky and building noise, together with shadowing and satellite constellation statistics. Leads to calculation of effective statistical G/T, and permits specification and optimisation of antenna radiation patterns. ● Rapid electromagnetic simulation for both antenna and propagation modeling using Finite Difference Time Domain simulators. Rapid, simple 2D simulator and efficient parallel 3D simulators produced. Used to calculate the interaction of S-PCN antennas and the human body. cm

cm

dB

Prediction of radiation from a satellite-mobile handset in close proximity to the human head

2.0 Other research areas related to broadband satellite communications are as follows: A number of projects are being undertaken in the Broadband Multimedia Satellite area. These are concerned with Multimedia Services above the 64-144 kb/s region dealt with in UMTS studies and reach up to 2-100 Mb/s. An EU ACTS project, SECOMS, forms much of the effort and this is looking at delivery of Multimedia to lap-top, and palm-top terminals at Ka-band and ehf respectively from a GEO satellite. Another project, GIPSE, is looking at new and hybrid constellations for such delivery. The work involves both air-interface studies in which synchronous CDMA is a feature together with advanced modulation and channel coding as well as networking issues such as ATM modification for both the satellite traffic and control planes, resource and bandwidth management and congestion control. In addition work on on-board-processing including on-board ATM switching and switch management as well as efficient digital implementation of on-board equipment. Particular topics are: ● Advanced CDMA Receiver Architectures for Satellite Multimedia Communication ● Call Handling for ATM Over Satellite ● Congestion Control Techniques ● ATM on-board satellite ● Resource management and bandwidth reservation mechanisms 14

● Channel Coding Schemes ● Network optimisation ● Propagation measurements and channel characterisations for all the environment categories at Ka band

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

Possible System architecture for Broadband Satellite Communications based on ATM

3.0 Terrestrial Mobile Communications 3.1 Optimization of GSM network The work has concentrated on reduction of signalling traffic and database transactions within the GSM network. A novel location tracking method has been proposed and evaluated both analytically and through simulations. The proposed technique has resulted in substantial reductions in DB access and a reduction of total network signalling load under most operating conditions.

MOBILE COMMUNICATIONS RESEARCH GROUP

System architecture

A distributed mobility management scheme is also proposed that can also result in significant reductions in signalling traffic compared with the existing GSM scheme. Evaluation and application of optimization algorithms ( NN, GA and SA ) to the problem of optimal location area partitioning within cellular networks have been extensively researched. The aim is to reduce the signalling traffic over the air-interface through optimal design of LAs and support of “personal location areas” concept.

3.2 Cordless-Cellular interworking in the context of migration to UMTS Identification of an alternative registration method in the combined system according to the similarity and dissimilarity of air-interface and network and also the level of integration or interworking. This will consider the deployments of new technologies such as IN concept in the system.

● Support of both personal mobility and terminal mobility for dual-mode user

● Identification of a location updating procedure

● Service mobility (service migration to different elements) for dual-mode user

● Identification of paging strategy

● Seamless handover & roaming between Cordless/Cellular using DECT and GSM as example systems and satellite coverage for multi-mode terminals

● Identification of call routing strategy ● Signalling load evaluation ● Multi-mode terminal functionality

● Handover optimization in hierarchical cell architecture 15

3.3 Software Telecommunication

MOBILE COMMUNICATIONS RESEARCH GROUP

This aims to investigate the applications of new software technologies such as Mobile and Intelligent Agents JAVA and CORBA for realisation of future software telecommunications scenarios. Such techniques could change the conventional management mechanism and offer more intelligence, flexibility and robustness, contributing to a suitable platform for open communication system infrastructure. In particular we are investigating design and specification of software radio based terminals and base stations. The resulting flexibility and re-configurability of a software based communication system will enhance service provision, help realise VHE concepts and bring about capacity and coverage improvements. Other benefits include :

3.4 Packet Communications The following areas are being extensively investigated: ● network independence

● capacity

● seamless roaming

● upgradeability

3.4.1 Reservation Random Access (RRA) Protocols ● General analysis ● Statistical upper bound study ● Performance comparison of 15 RRA protocols against each other

● Performance optimisation through dynamic contention mechanisms ● Guidelines for RRA protocols in cellular design

3.4.2 Hybrid Multiple Access Protocols Communications ● Three different hybrid multi-access protocols based on TDMA/CDMA, DTDMA/CDMA, PRMA/CDMA

● Link quality control procedures

3.4.3 Aggregate Finite-Source Modelling for Multimedia Communication Systems Dimensioning An aggregate source model is proposed by which the whole multi-service queuing system can be modelled with a mono-service M/G/c/N/FCFS queuing system.

3.5 Frequency Planning We have developed an automatic frequency planning & optimisation tool, based on the Genetic Algorithm. The novelty of this work lies in optimisation of Initialisation and Objective Function which together makes the GA convergence rate extremely fast so that the algorithm can also be used on the fly in an operating system for fast Dynamic Channel Allocation (DCA). Another aspect of this tool is the enhanced stability for GA, a feature which makes GA now suitable for such applications.

3.6 Multi-User Detection for CDMA The work on Genetic algorithms is now extended and optimised for joint-detection for both S-CDMA and A-CDMA. The technique has been compared with Convention Detector (Single User Detector) as well as Multi-Stage Detectors (MSD) with 10 stages. The single user bound is achievable and because of fast convergence rate, it is highly adaptable to fast channel changes due to fading and channel loading. The current work on GA is reduction of the implementation complexity whilst keeping the performance. In parallel we are also investigating Neural Network based Joint Detectors for CDMA. 16

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

● Channel Estimation Techniques

● Acquisition and Tracking particularly for packet CDMA

● Amplifiers for UMTS

● Interference Analysis CDMA

● End-to-end modelling and performance of UTRA

● Cellular System Modelling currently configured for GSM and can be changed for CDMA ● OFDM/MC-CDMA/Call Admission Control

● Interference cancellation in CDMA / TDMA overlay

● Predictive and adaptive power control schemes

● Overlapped carrier CDMA

3.7 Propagation 1. Multiple Edge Diffraction: Fast, accurate calculation of multiple edge and multiple cylinder diffraction, using deterministic numerical techniques. Applications: Urban / suburban area coverage and reuse prediction, terrain diffraction for point-to-point links. 2. Modelling and measurement of spatial and angular shadowing correlation for macrocells and picocells. Application to sectorisation, adaptive antennas, power control etc. 3. Measurement and statistical modelling of time-variant fading for line-of-sight links. Rapid time variant fading occurs due to vehicle and foliage motion combined with multiple scattering effects, as well as atmospheric and precipitation effects. These can lead to very rapid fading, having significant impact on performance and optimum system design. Applications include wireless local loop, MVDS and BRAN systems. Models allow prediction and simulation of time-variant effects for performance prediction and modem design. 4. Path loss models for direct mode mobile communications, such as TETRA. Physical-statistical models for picocell prediction, combining semi-deterministic path loss prediction with statistical prediction of spatially correlated shadowing effects. 5. Intelligent picocells, using intelligent antenna technology to provide high capacity indoor coverage solutions with distributed processing for plug-and-play, modular operation. Incorporates aspects of distributed antennas, diversity, optimum combining / beamforming, dynamic channel allocation and equalisation.

Received Field Strength [dB]

12

MOBILE COMMUNICATIONS RESEARCH GROUP

● Advanced RAKE receivers

Field Strength, module n: 1 at floor: 3

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Measurement and predictions of Field Strength in an Indoor Environment at 17GHz -colours indicate path loss values in decibels 17

4.0 Wireless LAN

MOBILE COMMUNICATIONS RESEARCH GROUP

New challenges associated with the mobile stations that are being addressed, such as location management, registration (including authentication and network security) and handover implementation.

4.1 Mobility management and Call control in a wireless ATM LAN Investigation of suitable MAC and DLC layers is being taken place. The HIPERLAN and IEEE 802.11 MAC layers have been tested using both an analytical and a simulation model. Delay and throughput deficiencies led to the development of a novel TDMA based MAC layer with better performance characteristics.

4.2 Ad-Hoc Computer Networking Most of the work, in wireless LAN has been concentrated on star topology configurations. This research is on distributed wireless computer networking, researching on Dynamic Routing algorithms for a wide range of mobility for the terminals, and implications on TCP layer and mobile IP, as well as multiple access techniques for guaranteeing QoS. ● an extension of HIPERLAN specifications to support optimally ATM traffic, ● the definition of an ATDMA based multiple access, introducing traffic policing on the air-interface

● a technique for modifying NNI specifications to support mobility in a wide area ATM network with wireless access points ● the design of an OFDM based transmis sion path for the ATM WLAN with variable channel coding rate.

4.3 Antenna & Propagation 1

Space-time channel modelling for adaptive antenna systems operated in indoor/outdoor environments at 2 and 5GHz. Four-channel measurement system under construction to measure correlations in space and time.

2. Measurement of propagation at 17 & 60GHz using remote controlled platform. Measurements in modern and Victorian office buildings, including indoor-outdoor and building-building scenarios. Leading to accurate physical-statistical prediction techniques. 3. Simultaneous Propagation Measurements at 17 & 60 GHz using a remote controlled mobile platform. Measurements in a variety of buildings from the Victorian-era to modern day, including indoor to outdoor and building to building scenarios. Leading to accurate physical-statistical prediction techniques. 4. Intelligent picocells, using intelligent antenna technology to provide high capacity indoor coverage solutions with distributed processing for plug-and-play, modular operation. Incorporates aspects of distributed antennas, diversity, optimum combining / beamforming, dynamic channel allocation and equalisation. Rapid electromagnetic simulation for both antenna and propagation modelling using Finite Difference Time Domain simulators. Rapid, simple 2D simulator and efficient parallel 3D simulators produced. 6. CCSR has a modern specially equippped Radio Frequency Laboratory, featuring the following key test and measurement capabilities: ● Vector Network Analyser up to 26.5 GHz

● Signal Generator up to 75 GHz

● Spectrum Analyser up to 75 GHz

● Digital Storage Oscilloscope with 500 MHz bandwidth

● Power Meter up to 40 GHz

18

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

MULTIMEDIA SYSTEMS RESEARCH GROUP Aims The main research activities of the group are in the area of low and very low bit rate speech and video compression algorithms with improved error robustness and efficient channel coding, encryption and water marking techniques as well as new modulation and coding schemes and the DSP and ASIC implementation of satellite OBP.

● Development and implementation of the AUDETEL codec which is currently undergoing acceptance tests being conducted by the ITC.

● Development and performance study of an error resilience algorithm for H.263 and its comparison with other techniques found in the literature such as EREC

● Development of two new speech codec algorithms

● Two-way decodable entropy coding for MPEG-4.

● Pulsed Residual Linear coding for bit rates of 4.8 kbit/s and over

● Adaptation of MPEG-4 applications for satellite and terrestrial (indoor/outdoor) environments.

● Time Envelope Vocoding for rates from 1.2 to 2.4 kbit/s

● New Turbo code implementations

● Development of a novel lossy multiplexing technique for thin route telephony

● New applications and implementations of RS codes

● Demonstration of the novel concept of source-aided channel decoding for increased error control performance for speech codecs

● Reduced complexity on board satellite VLSI demultiplexers

● Improvements to the error robustness and lost information recovery of ITU H.261 and H.263 video codecs.

MULTIMEDIA SYSTEMS RESEARCH GROUP

Achievements

Description 1

Low Bit Rate Speech and Audio Coding

1.1 Split-Band LPC Vocoder The aim of this project is to develop a new type of low bit rate speech coder. By assuming that the spectrum of the speech is voiced for the low frequencies and unvoiced for the high frequencies, this coder gives a very high quality even at very low bit rates. Different versions, at 2.4 kbit/s, 4.0 kbit/s, 5.5 kbit/s and 6.2 kbit/s, have been developed. They give better speech quality than the full-rate GSM standard, which makes them suitable for mobile applications.

1.2 Wideband SB-LPC Vocoder An advantage of a wideband speech (sampled at 16 KHz) over a narrowband speech(sampled at 8 KHz) is that it sounds more natural and pleasant to human ear. This is due to the better preservation of the speech dynamics during the higher sampling process. Therefore, the ultimate goal of this project is to develop a wideband LPC vocoder which, when quantised, should operate at the rate of around 8.5 kbit/s. This coder uses a split-band voicing technique which has proved successful at very low bit rates. Current results promise a high-quality speech coder ready to compete in the market with other wideband coders.

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1.3 Low Bit Rate Speech Coder Based on CELP Coder The coder is applied to encode the narrow band speech signal (4 KHz) and decode the wideband speech signal (8 KHz) at the receiving end. This will enhance hi-fidelity and the naturalness of the speech. The ultimate aim is to achieve the decoded speech signal which sounds more pleasant than the original one.

MULTIMEDIA SYSTEMS RESEARCH GROUP

1.4 Low Bit Rate Audio Coding Applications involving digital transmission and/or storage of high quality audio signals, such as Digital Audio Broadcasting and Multimedia, require low bit rates. The research area of digital audio coding is currently developing a time-domain scheme which achieves 1 bit/sample compression. The overall bit rate will of course depend on the sampling frequency of the analog audio. Our present work has been concentrated on the sampling rate of 16 KHz producing a very interesting bit rate of 16 kbit/s. The project employs CELP (Code Excited Linear Prediction) coding algorithm and noise masking techniques so as to achieve good quality at the low bit rate. The audio quality produced at 16 kbit/s is very acceptable for low bit rate applications and has already created significant interest from the industry.

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Image and Video Coding

2.1 Reduced Resolution Updating For fixed-rate video coding, a sudden increase in the amount of bits generated by the codec, caused by short-term changes in the video content, is undesirable as this will increase the time delay. By reducing the resolution in each dimension by half, the amount of bits spent on coding the motion-compensated difference signal will be reduced greatly. Fixed bit-rate variable frame-rate controller will be used.

2.2 Object Detection and Rate/Quality Optimisation in MPEG-4 Video coder To take advantage of the content-based functionalities provided by MPEG-4, the scene must be searched for the contour of the enclosed VOPs. MPEG-4 does not explicitly specify any technique for the detection of objects in the video scene. The door is left open for researchers to combine their efforts in order to incorporate an efficient object detection algorithm for the alpha plane encoding. This project aims at providing an algorithm for an efficient and low-complexity detection of the object borders. On the other hand, the project examines the efficiency of binary shape coding defined by MPEG-4 and aims at optimising the quality against the bit rate generated by the alpha plane encoder.

2.3 Source and Channel Coding for Mobile Multimedia Communications In this project, the performance and robustness of H.263 and H.261 were compared and focus has been made on the study of the error sensitivity of various video parameters in H.263. Furthermore, the error resilience aspects of the coder were examined and a set of several error resilience techniques have been implemented on H.263 to enhance its performance in error-prone environments. A novel error resilience algorithm has been developed and its performance was compared to that of the techniques found in the literature such as EREC. Two-way decoding and RVLC were applied on H.263 to mitigate the effect of channel errors on the video quality.

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Quality Improvement with an Error/Rate Control Mechanism Using Feedback

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

2.4

Video Coding Algorithm for Wireless ATM Networks

This project aims at improving the transport of video intended for video conferencing applications. The H.263 low bit rate algorithm is to be modified for transport over wireless ATM channels. The project involves modification of the syntax of H.263 in order to adapt it to the mobile environment. Modifications include both source and channel level with prospects of channel assisted decoding.

H.263 EREC Frames on Wireless ATM Networks

3

Channel Coding

MULTIMEDIA SYSTEMS RESEARCH GROUP

Quality Improvement Using Two-Way Decoding and Reversible Codewords

3.1 Trellis Decoding of Cyclic Block Codes This project extends previous work in which it was found that Reed Solomon codes could use soft decisions from the demodulator to give performance and complexity comparable with convolutional codes on the AWGN channel. Methods being investigated include representation of the codes as binary codes, development of sequential decoding methods and trellis re-ordering techniques. Appropriate metrics for a range of channel conditions will also be investigated.

3.2 Algebraic Decoding of Cyclic Block Codes Methods using the algebraic properties of block codes have speed advantages and can be adapted for soft decision decoding. Investigation of an algorithm proposed by Dorsch showed that it was more suited to binary than to multilevel codes, however other methods investigated have produced impressive results. An extension of the Kasami algorithm is shown to have significant computational advantages over Minimum Weight Decoding and a novel method based on re-ordering and error trapping provides low complexity decoding of Reed Solomon codes.

3.3 Cryptography for Images and Video A range of issues are being investigated to resolve specific requirements of applications involving images and video. Achievements include: ● Definition of a method for certifying images from digital cameras. ● Development of a low-complexity method for encryption of compressed images and video.

● Development of source key distribution schemes for subscription broadcast services using smart card controlled set top boxes. ● Development of methods for hiding cipher text.

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4 4.1

Modulation and Coding Turbo Coded Modulation for Fading Channels

MULTIMEDIA SYSTEMS RESEARCH GROUP

We are aiming at creating error robust coded modulation schemes for fading channels using the turbo coding scheme. In particular, we are investigating the characteristics and suitability of various constituent encoders in the appropriate channel conditions.

Performance of our low-complexity Turbo Coding Scheme

4.2 Ground-Satellite Optical Communications We are studying system design/analysis of ground-satellite optical communication links, aimed at deriving well-defined guidelines with necessary tools in the form of graphs, tables, algorithms, simulation models etc. We have been concentrating on the issues which are not common with optical intersatellite links, namely atmospheric propagation. Atmospheric turbulence causes fluctuations in amplitude and phase of an optical beam propagating through it. We are planning to conduct optical turbulence measurements based on the analysis of bi-dimentional spatiotemporal spectra of stellar light in collaboration with the Communications Research Laboratory in Japan.

4.3 Robust Coded Modulations The objective of this project was to develop bandwidth-efficient coded modulations that would be robust across a range of channel conditions. Achievements include: ● Development of a combination of set partitioning techniques, a novel expanded rotated detector and a multistage decoding method allowing Reed Solomon codes to be applied with hard decision demodulation.

● Development of techniques for reduction of peak-to-mean power ratio in OFDM. ● Development of concatenated RS-RS coding schemes for multilevel modulations on OFDM.

● Performance across a range of channel conditions comparable with, or better than, other trellis coded and block coded modulations.

4.4 Development of Algorithms for ASIC Implementation of DVB .0QPSK Demodulator This project has been undertaken in conjunction with industry, in order to develop synchronisation algorithms for a QPSK demodulator for the reception of signals conforming to the ETSI DVB-S standard, Digital Video Broadcasting via satellite. The DVB standards renders the symbol rate completely unspecified, and hence imposes tremendous difficulties in terms of aliasing-avoidance in the sampling process due to the variable bandwidth, symbol rate and automatic frequency control. 22

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

COMMUNICATION NETWORKS RESEARCH GROUP Aims ● To study ATM and INTERNET for satellite and terrestrial systems supporting broadband communications and multimedia services.

● To study Network and Service Management using Object-Oriented TMN and TINA principles

● Design and implementation of protocols stacks with security solutions for accessing to Paris and Brussels Stock Exchanges. ● Study and Development of “system-onchip” solution for future ISDN switch and internetworing technology. ● Validation of Integrated Architectures based on the emerging CORBA/TINA framework for integrated multimedia services and network management. ● Study of Mobile Intelligent Agents Management and examines applicability of MIAs to TMN / TINA.

● Investigation of Internet and ATM Convergence and Integration IPv6 with resource reservation over ATM, pan-European trials. ● Developed and refined an integrated voice and data multiple access scheme for a VSAT satellite network ● Developed a new and efficient traffic control mechanism for ATM ● Demonstrated and tested the interconnection of LANs via an ATM satellite link

Description 1.0 ATM and Broadband Communications 1.1 THESEUS (Terminal at High Speed for European Stock Exchange Users)

COMMUNICATION NETWORKS RESEARCH GROUP

Achievements

The objective of this project is to develop a terminal that will be a key component of an open system and able to meet the telecommunication needs of the future European capital market. The project aims to develop a universal terminal that will use low-level ATM properties to encapsulate data units, whatever the application layers maybe, and to display information exchanged between several stock exchanges on a single screen, through appropriate multi-windowing software. A representative sample of European stock exchanges are co-operating actively on the project from project definition through to the validation and analysis of the demonstration results.

1.2 TCP/IP over ATM TCP/IP is the most widely used protocol in the computer communications area. Although it has been used globally in LAN/MAN/WAN environments for years, it is not optimised for high-speed networks such as ATM. The Communication Networks Research Group is carrying out experiments to test the performance of TCP/IP over ATM and to find ways to optimise it so that current applications can make use of the high-speed networks such as ATM.

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1.3 Security Systems for ATM Networks We have research in security system requirements to protect user, control and management planes in ATM networks. Specific areas of interest are: ● User plane: To provide end-to-end security services where the ATM network passes the user information (ATM cell payload) without any security processing

COMMUNICATION NETWORKS RESEARCH GROUP

● Control and management planes: To protect signalling and management messages using public-key systems and timestamps

● Public-key distribution: Between end systems and network nodes as well as between network nodes ● Parallel ciphering: To provide fast encryption techniques suitable for ATM high data rate services

THESEUS Main Architecture

2.0 Network and Service Management 2.1 VITAL This project concerns Validation of Integrated Telecommunication Architectures for the Long-term and Validation of the emerging TINA framework for integrated multimedia services and service/network management. We are mainly involved in ATM resource configuration and connection control through the management plane.

2.2 REFORM It is to study Resource and Fault restORation and Management Close integration of control and management, ATM-F PNNI signalling integrates VPC recovery, ATM network management based on CORBA/TINA principles. Our involvement is in ATM VPC configuration, planning activities and algorithms for dynamic bandwidth (re-distribution).

2.3 FlowThru This project is a Trial Integration of the results of the VITAL, REFORM and PROSPECT projects integrated TINA-based multimedia service management with both TMN and TINA-based ATM network management. This work is mainly relevant to the VITAL, REFORM project plus ATM accounting management issues. 24

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

2.4 MIAMI Concerns Mobile Intelligent Agents in the Management of the Information Infrastructure and Examines applicability of MIAs to TMN / TINA. It uses the OMG CORBA emerging mobile code solution involvement in ATM QoS management issues

3.0 Network Access and Interworking

In order to stimulate the growth in the ISDN market, the ESPRIT COPARIS project will develop an application-specific embedded processor capable of implementing a large subset of the existing ISDN line interface standards. This will be the forerunner of a generation of advanced telecommunications processors using OMI subsystems that can be extended into a range of future applications. As an example, it will allow the production of ISDN home PBXs with a cost of about 50% compared to today’s equivalent products.

COMMUNICATION NETWORKS RESEARCH GROUP

3.1 COPARIS (Common Physical Access Chip for ISDN Systems)

Internal COPARIS Architecture

3.2 IthACI Will study Internet and ATM Convergence and Integration IPv6 with resource reservation over ATM, pan-European trials. CISCO is involved in the development of IP/ATM QoS management.

3.3 Integrated Service VSAT Satellite Access Protocol There is an increasing demand for VSAT networks that can provide integrated voice and data services. This explores and develops VSAT protocols that can best meet these requirements. Using analytical and simulation methods, we have studied the performance of a variety of candidate access schemes that could be used in this scenario such as Reservation Aloha, Selective-Reject Aloha, Selective-Reject Aloha FCFS with Reservations, and Multiple Channel CRA. We have looked at the problems that the introduction of packetised speech introduces to the system and ways to deal with them. We have looked at voice/data integration at two levels: Firstly, by using a combination of voice channels and data channels and optimising the way we allocate these with respect to the available traffic, and secondly, by taking advantage of the silences in the voice channels and transmitting data packets during the longer silence intervals. 25

4.0 Internet and ATM over Satellites 4.1 CATALYST

COMMUNICATION NETWORKS RESEARCH GROUP

The CATALYST project tested satellite technology in relation to the terrestrial Integrated Broadband Communications (IBC) network. We analysed end-to-end system communications for client-to-server architectures across Asynchronous Transfer Mode (ATM) links and satellite relays, interconnecting Ethernet, DQDB and FDDI networks. The project demonstrated the world’s first ATM connection via satellite at Nanteer, in Paris. This showed the capability of ATM via satellite to support interactive images, joint viewing, multimedia communications and network file systems.

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4.2 Internet and B-ISDN via Satellite The aim of this project is to investigate efficiency of the ATM and Internet protocols including the next generation of IP (IPv6) that would enable communication satellites to offer Internet and B-ISDN services. The research concerns satellite network architectures, protocol performance and optimisation and simulation prototype and validation.

4.3 Satellite Constellations Low-earth orbiting (LEO) satellite constellations offer the possibility of full world-wide wireless networking, better support for high latitudes than provided by Geo-stationary Earth Orbit (GEO) satellites, and with decreased time delay over GEO. Ensuring seamless interworking with existing ground-based networks raises complex networking issues, as does attempting to model the performance of a network based on a rapidly-changing LEO satellite constellation or considering guaranteed-quality multimedia services over such a constellation. We are researching network topologies and simulation techniques to better understand these problems.

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

4.4 Security Systems for Satellite Networks

● Security protocol efficiency to prevent long delays and bandwidth consumption.

● Data encryption using a secret-key algorithm.

● Mutual and unilateral authentication between the satellite-user and satellite network using public-key cryptosystems.

● Access control

COMMUNICATION NETWORKS RESEARCH GROUP

Security system requirements to improve the data and voice services provided by satellite networks. Specific areas of interest are:

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CCSR STAFF ●

Director Professor Barry G Evans, BSc, PhD (Leeds), FEng, FIEE, SMIEEE, FRSA

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Deputy Director Professor Ahmet M Kondoz, BSc (Birm), MSc (Essex), PhD (Sur), CEng, MIEE, MIEEE, (Head of Multimedia Systems Research Group)

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Academic Staff Ms Frances Coakley, BSc, MSc (Manc), C.Eng, MIEE, MIEEE, (Senior Lecturer) Mr Tony Jeans, MA (Camb), MSc (S’ton), (Senior Lecturer) Dr Abdul H. Sadka, BSc (AUB), MSc (METU), PhD (Surrey), (Lecturer) Dr Simon Saunders, BSc (Brunel), PhD (Brunel) AMIEE, MIEEE (Lecturer)

CCSR STAFF

Dr Zhili Sun, BSc(China) PhD (Lanc), (Lecturer, Acting Head of Communication Networks Research Group) Dr Peter Sweeney, MA (Oxon), PhD (Camb), (Senior Lecturer)

●

●

Mr Cheng Jinwu Mr Chris Meenan (Mobility management in SPCN) Mr Ioannis Mertzanis (Networking aspects & QoS provisioning for mobile satellite multimedia services) Mr Tolga Ors (Traffic management and control over ATM via satellite networks) Mr Heng Pan (Satellite communications management)

Mr David Brock (MSc Surrey,C. Eng.MIEE)

Computing Officers

Mr Pouya Taaghol (Wireless packet communications)

Technician PA to Director/Centre Secretary Financial Assistant Secretary to Research Groups Mrs Lakshmi Chennell

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Dr Bachir Belloul Dr Haitham Cruickshank Mr Shahram Ghaheri Niri (Integration between cordless and cellular systems)

Dr Riaz Suddle Mr Payam Taaghol (Power control for CDMA)

Mrs Stephanie Evans ●

Mr Costas Apostolas (Study for multiple access schemes for ATM wireless LANs)

Technical & Financial Administrator

Mrs Moira Cook ●

Mr Andreas-Albertos Agius (Dual mode antenna for SPCN handheld terminals)

Dr Martin Parks Dr Haidar Radi Mr Tony Sammut (Resource management for satellite SPCN)

Mr Terry Roberts ●

Research Fellows/Assistants (PhD subjects where applicable)

Dr Rahim Tafazolli, BSc (Bath), MSc (Lond), PhD (Surrey), MIEE, MIEEE, (Reader) Head of Mobile Communications Research Group)

Mr John Hibbitt Mr Adam Kirby ●

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Mr Seiamak Vahid (Optimisation of GSM networks) Mr Cyril Valadon (Advanced CDMA receivers for satellite multimedia communication systems) Miss Greet Verelst (Satellite on-board processing for multimedia communications) Mr Stephane Villette (High quality low bit rate speech coding) Dr Stephan Wesemeyer

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

Research Students (PhD subjects)

Mr Dionisis Adamopoulos (Design and management of telematic services - the case for Greece) Mr George Aggelou (Ad Hoc wireless networking) Mr Bilal Ahmed (Ka Band channel for satellite mobile multimedia services)

Mr Stephen Leach (Optimum control of hand portable terminal antennas for mobile communications) Mr Teck Hock Kweh (Improved Quality Block-Based Low Bit Rate Video Coding) Mr Klaus Moessner (Software radio) Mr K Narenthiran (Mobile satellite communications)

Mr Thumrongrat Amornraksa (Cryptography for multimedia communications)

Mr Min-Seok Oh (Binary Reed-Solomon decoder for multi-channels)

Mr Ilias Andrikopoulos (Optimising TCP/IP over ATM networks)

Mr John Paffett (Interference avoidance techniques)

Mr Mehrdad Ardebilipour (Code Synchronisation for pocket CDMA)

Mr Philip Psiloinis (Video conferencing for wireless ATM networks)

Mr M. Hafeez Aziz (Band sharing between CDMA based CDMA) Mr Damon Birch (CDMA for satellite broadband communications) Mr Yotsapak Chotikapong (TCP/IP over ATM via satellite constellations) Mr David Cooper (Communications using Mains for transmission) Mr Nikolaos Dimitriou (CDMA for multimedia) Mr Kjetil Fagervik (Interactive decoding techniques) Ms Bin Fan (Call handling for ATM via satellite) Miss Maria Farrugia (Audio and speech signalling) Mr Mauro Fiacco (Intelligent picocells using optimum combining) Mr Hai Pang Ho (Soft decision decoding of Reed-Solomon codes) Mr Jong-Ok Joo (Optimisation of ATM switch on -board satellite for multimedia)

Mr George Sfikas (Call handling and mobility management for satellite SPCN) Mr Chana Sriratanaban (Low bit rate speech coding) Mr Milos Stefanovic (Low bit rate speech coding) Mr Stavros Stavrou (The accuracy of mobile propagation measurements)

CCSR STAFF

Mr Saied Abedi (Multi-user Detection)

Mr Nhong Suvannapattana (Interaction of satellite mobile hand-held with human body) Mr Rajan Thiruvathirai (Software radio) Mr Constantinos Tzaras (Physical modelling of mobile propagation) Mr Lloyd Wood (Multicast over satellite constellations) Mr Len Woodhead (Coded modulations) Mr Yusuf Yenice (System design/analysis of ground-satellite optical communications)

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Visiting Students Mr Adrian Cortier

Mr Claude Oesteges

Mr Safak Dogan

Mr Jiangfeng Li

Awarded PhDs

Chronological list of awarded PhDs in CCSR over the last 3 years: Cullen C J, “Network and signalling Aspects of Satellite Personal Communication Networks”, March 1995. Danesfahani G R, “A study in Optimising a Multicarrier Demultiplexer Demodulator (MCDD) for On-Board Processing (OBP) Satellites”, April 1995.

CCSR STAFF

Eryurtlu M O F, “New Approaches in Low Bit Rate Image & Video Coding”, June 1995. Hadjitheodosiou M, “Performance Optimisation of Multiple Access Protocols for Multi-Service VSAT Networks”, June 1995. Tafazolli Rahim, “Multiple Access Protocols for Third Generation Cellular Mobile/Personal Communication Systems”, February 1996. Suddle Riaz, “Speech Coding in Private and Broadcast Networks”, March 1996. Qi Ronggang, “Multicarrier Demultiplexing and VLSI Implementation for Processing Satellite Communication Systems”, July 1996. Finean B, “The Role of Mobile Satellite Systems in FPLMTS”, September 1996. He Xiaoping, “The Signalling System in Satellite - Personal Communication Networks”, November 1996. Parks Martin, “Wideband Propagation Channel Characterisation Applicable to Mobile Satellite Systems at L- and S- Bands”, December 1996.

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Smith Christopher, “Quality of Service Issues in Digital Mobile Technology”, December 1996. Atkinson Ian, “Advanced Linear Predictive Speech Compression at 3.0 kbit/sec and below”, February 1997. Black Alastair, “Analysis by Synthesis Coding of Narrowband and Wideband Speech at Medium Bit Rates”, May 1997. Yaghmaie Khashayar, “Waveform Interpolation Based Low Bit Rate Speech Coding”, June 1997. Tateesh Said, “Multi-Rate Source and Channel Coding for CDMA-Based Mobile Communications”, September 1997. Sadka Abdul H, “Error Control Strategies in Block-Transform Video Coders in Multimedia Communications”, September 1997. Zhao Wei, “Handover Techniques and Network Integration Between GSM and Satellite Mobile Communication System”, September 1997. Husni Emir, “Robust Reed Solomon Coded MPSK Modulation”, November 1997 Lee Joohee, “CDMA Overlapped Carrier Allocation Schemes for Cellular Mobile Communications”. November 1997.

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

PUBLICATIONS Alphabetical list of conference and journal publications by researchers in CCSR over the last 3 years.

CCSR PUBLICATIONS LIST FOR 1997 CONFERENCE PAPERS

Agius A A, Saunders S R, Evans B G, “The Design of Specifications for Satellite PCN Handheld Antennas.” Vehicular Technology Conference (VIC) 1997, IEEE, Arizona, USA. 4-7 May 1997. Agius A A, Saunders S R, “Intelligent Antennas for Mobile Handsets”, 1st Surrey Symposium on Intelligent Antenna Technology for Mobile Communications, 28th to 29th August 1997, University of Surrey. Ahmed B, Buonomo S, Otung I E, “Simulation of 20 Ghz narrow Band Mobile Propagation Data Using N-States Markov ChannelModelling Approach.” 10th International Conference on Antenna and Propagation, Edinburgh, UK, 14-17 April 1997. Apostolas C, Tafazolli R, “Dynamic TDMA scheme with Traffic Policing for ATM Wireless LAN” 9th Tyrrhenian International Workshop on Digital Communications, Lerici, Italy, 7-10th September 1997. Atkinson I, Yeldener S, Kondoz A, “High Quality Split Band LPC Vocoder Operating At Low Bit Rates.” International Conference on Acoustics, Speech and Signal Processing (ICASSP) Munich, Germany, 21 April 1997. Aziz H, Tafazolli R, Evans B G, “Comparison of Total System Capacity for Band Sharing between CDMA based non-Geostationary Satellite-PCNs under Imperfect Power Control Systems” IEEE 47th Annual International Vehicular Technology Conference (VTC 97) Phoenix, USA, 4-7th May 1997. Belloul B, Saunders S, Evans B G, “Diurnal variability of scintillation intensity on a moderate elevation Earth-satellite path at 12.5, 20 and 30 Ghz” COST 255, Brussels, 27-29 October 1997. Buracchini E, Melis B, Romano G, Taagho lP, “SINUS Air Interface Overview” 3rd ACTS Mobile Communication Summit, Aalborg, Denmark, 7-10 October 1997.

Cruickshank H S, “Securing User, Control and Management Planes In ATM Networks.” Singapore International Conference On Networks 1997 (SICON 97). Singapore, 14-17 April 1997. Fagervik K, Jeans T G, “A Polar Automatic Frequency Control Algorithm for Low Signalto Noise Ratios.” Norsig 199, IEEE Norway Section, Tromso, Norway, May 1997. Fiacco M, Saunders S R, Evans B G, “Design & Simulation of Intelligent Picocells”, 1st Surrey Symposium on Intelligent Antenna Technology for Mobile Communications, 28th to 29th August 1997, University of Surrey. Ho H P, Sweeney P, “Extended Kasami Algorithm” 6th IMA International Conference on Crytography and Coding, Cirencester, December 1997. Husni E, Sweeney P, “Robust Block Coded MPSK Modulation for the Gaussian and a Rayleigh Fading Channel” IMSC’97, Pasadena California, USA, June 1997. Husni E, Sweeney P, “Robust Block Coded MPSK Modulation” 4th International Symposium on Communication Theory and Applications, Ambleside, July 1997.

PUBLICATIONS

Agius A A , Saunders S R, Evans B G, “Antenna Design For The ICO Handheld Terminal.” International Conference On Antennas & Propagation (ICAP 1997). IEE, Herriot Watt University, Edinburgh, UK. 14-18 April 1997.

Husni E, Sweeney P, “Robust Reed Solomon Coded MPSK Modulation” 6th IMA International Conference on Cryptography and Coding, Cirencester, December 1997. Koudelka O, Maral G, Cruickshank H, Collard J, “Network integration via MEO/LEO satellites-The COST 253 action” IEE Colloquium on EU’s initiatives in satellite communicationsfixed and broadcast, London, 9th May 1997. Lee J, Tafazolli R, and Evans B G, ”Erlang capacity of OC-CDMA imperfect power control”, IEE Eletronics Letters, pp. 259-261, 13th Feb vol 33, no 4, 1997 Meenan C, Tafazolli R, Evans B G, “Mobility Management and its Impact On Call Routing in Dynamic Satellite Personal Communication Networks.” International Mobile Satellite Conference, Pasadena, USA, June 1997.

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Meenan C, Tafazolli R, Evans B G, “Intelligent Paging Schemes for Non-Geo Satellite Personal Communication Networks.” Vehicular Technology Conference 1997,IEEE Phoenix Arizona, USA, 4-7th May 1997. Meenan C, Tafazolli R, Evans B G, “New Mobility Management And Call Routing Protocols For Dynamic Satellite Personal Communication Networks.” Integration of Satellite Terrestrial PCS, IEE London, April 1997. Meenan C, Tafazolli R, Evans B G, “Intelligent Paging in Dynamic Satellite Personal Communication Networks.” International Mobile Satellite 1997, Pasadena, USA, 19 June 1997. Meenan C, Tafazolli R, Evans B G, “Mobility Management and its Impact On Call Routing in Dynamic Satellite Personal Communication Networks.” International Mobile Satellite Conference, Pasadena, USA, June 1997.

PUBLICATIONS

Mertzanis I, Tafazolli R, Evans B G, “Protocol Architecture Scenarios for Satellite and B-ISDN Network Integration” 3rd Ka-Band Utilisation Conference, Sorento, Italy, September 1997. Mertzanis I, Fan B, Tafazolli R, Evans B G, “Signalling and Protocol Schemes for SECOMS, the ACTS European project” Fourth European Conference on Satellite Communications (ECSC-4), Italy, 18-20 November 1997. Mertzanis I, Tafazolli R, Evans B G, “Connection Admission Control Strategy and Routing Considerations in Multimedia (NonGeo) Satellite Networks”, IEEE 47th Annual International Vehicular Technology Conference, Phoenix, USA, May 4-7th 1997. Mertzanis I, Tafazolli R, Evans B G, “Performance Issues and Modelling of Mobile Executed Handoffs in Multi-Spotbeam Dynamic Satellite Networks using ATM Multiplexing”, IEE, Colloquium London, UK, February 1997.

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Sadka A H, Eryurtlu F, Kondoz A M, “Modified H.263 video coding algorithm for mobile multimedia communications”, 2nd Erlangen Symposium on advances in digital image communications, Erlangen, Germany, April 1997. Samarakoon M I, Honary B, Sweeney P, “Secure file transmission over multi-user networking environments” 4th International Symposium on Communication Theory and Applications, Ambleside, July 1997. Sammut A, Mertzanis I, Tafazolli R, Evans B G, “A Global Integrated Personal Satellite Multimedia Environment (GIPSE): Communications for the Next Millenium.” Proceedings of the Third Ka Band Utilization Conference, Sorrento, Italy, pp 429-434, 15 September 1997. Sammut A, Mertzanis I, Tafazolli R, Evans B G, “A Global Integrated Personal Satellite Multimedia Environment (GIPSE)” Fourth European Conference on Satellite Communication (ECSC-4), pp 11-15, Rome, Italy, 18-20 November 1997. Saunders S R, Evans B G, “A Physical-Statistical Model for Land Mobile Satellite Propagation In Built-Up Areas”, 10th International Conference on Antennas and Propagation, pp 2.44-2.47 14 th to 17th April 1997, Edinburgh. Sweeney P, Honary B, “Security and Information Representation for the Niederreiter Public Key Cryptosystem” 4th International Symposium on Communication Theory and Applications, Ambleside, July 1997. Taaghol P, Tafazolli R, Evans B G, “Performance Evaluation of an Adaptive Power Control Scheme in Measurement Based S-PCN Channel” IMSC’97, Pasadena, California, USA, 16-18 June 1997. Taaghol P, Tafazolli R, “Correlation Model for Shadow Fading in landMobile satellite System”, IEE Eletronics Letter, 17th July 1997 Vol.33 No.15, pp.1287-1289

Ors T, Sun Z, Evans B G, “A Meshed VSAT Satellite Network Architecture using an On-Board ATM Switch”, IEEE International Performance, Computing and Communications Conference 1997, PhoenixArizona, USA, 5-7th February 1997.

Taaghol Pouya, Tafazolli R, Evans B G, “On the Reservation Multiple Access Protocols for Future Mobile Communication Systems” IEEE 47th Annual International Vehicular Technology Conference, Phoenix, USA, 5-7th May 1997.

Parks M A N, Saunders S R, Evans B G, “Wideband Characterisation and Modelling of the Mobile Satellite Propagation Channel at L- and S- Bands.” Tenth International Conference on Antennas and Propagation, Edinburgh, 14 April 1997. (Proceedings vol.2 pp. 239-243)

Taaghol Pouya, Tafazolli R, Evans B G, “An Air Interface Solution for General Packet Radio Service (GPRS) for GSM/DCS” IEEE 47th Annual International Vehicular Technology Conference, Phoenix, USA, 4-7th May 1997.

Rautiola K, Tolonen M, Taaghol P, Tafazolli R, Evans B G, “Design of the Satellite Radio Channel Emulator for Real-Time Demonstrations in SINUS” 3rd ACTS Mobile Communication Summit, Aalborg, Denmark, 7-10 October 1997.

Tateesh S, Atungsiri S, Kondoz A M, “Link Adaptation to Channel Interference Using Multi-rate Source and Channel Coding for CDMA Mobile Communications.” International Conference on Acoustics, Speech and Signal Processing (ICASSP) Munich, Germany, April 1997.

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

Valadon C, Tafazolli R, Evans B G, “On Channel Coding for Satellite Multimedia Systems with a Synchronous CDMA Access Scheme.” International Mobile Satellite Conference’97, Pasadena California, USA, 16-18 June 1997. Valadon C, Taaghol P, Tafazolli R, Evans B G, “Design and Dimensioning of a CDMA Regenerative Payload for the SECOMS System” 4th European Conference on Satellite Communications, Rome, Italy, 18-20 November 1997.

Valadon C, Taaghol P, Tafazolli R, Evans B G, “SECOMS CDMA Link Dimensioning” 3rd ACTS Mobile Communications Summit, Aalborg, Denmark, 7-10 October 1997. Villette S, Stefanovic M, Atkinson I, Kondoz AM, “High Quality Split Band LPC Vocoder and its Fixed Point Real Time Implementation” Eurospeech ‘97, Vol.3, pp 1243-1246, Rhodes, Greece, 22-25 September 1997.

Valadon C, Taaghol P, Tafazolli R, Evans B G, “Link Design and Dimensioning of CDMA, the Alternative Multiple Access in SECOMS” 3rd Ka-Band Utilization Conference, Sorrento, Italy, 15-18 September 1997.

JOURNAL PAPERS

Amornraksa T, Sweeney P, Honary B, “Protecting the integrity of a sequence of images.”IEE Electronics Letters, Vol 33, Part 19, pp 1617-1618, September 1997. Atungsiri S A, Tateesh S, Kondoz A M, “Multirate Coding for Mobile Communications Link Adaptation.”IEE Proceedings On Communication, Vol. 144, Part 3, pp 211-216, June 1997. Eryurtlu F, Sadka A H, Kondoz A M, “Error Robustness Improvement of Video Codecs with Two-way Decodable Codes” IEE Electronics Letters, Vol.33, No.1, pp 41-43, January 1997. Hadjitheodosiou M H, Evans B G, Coakley F, “Next generation multiservice VSAT networks” IEE Electronics & Communication Engineering Journal, Vol.9 No.3, June 1997. Kweh T H, Eryurtlu F, Kondoz A M, “Closed – Loop Motion Compensation for Video Coding Standards.” IEE Proceedings – Visual Image Signal Process, Vol 144,Part 4, pp 227-232, August 1997.

Sadka A H, Eryurtlu F, Kondoz A M, “Error Resilience Improvement for BlockTransform Video Coders” IEE Proc. VISP, Vol.144 No.6, December 1997.”, Sadka A H, Eryurtlu F, Kondoz A M, “Improved Performance H.263 under Erroneous Transmission Conditions” IEE Electronics Letters, Vol.33 No.2, pp 122-124, January 1997. Sun Z, Ors T, Evans B G, “ATM-over Satellite demonstration of broadband network interconnection” Special Issue in Computer Communications Journal, Elsevier Science Publications. Taaghol P, Tafazolli R, “Correlation Model for Shadow Fading in Land-Mobile Satellite Systems” IEE Electronics Letters, Vol.33, No.15, pp 1287-1289, 17 July 1997.

PUBLICATIONS

Apostolas C, Sfikas G, Tafazolli R, “The UK LINK- PCP Approach to the Wireless ATM System“, Accepted for publication in IEEE Communications Magazine , Special Issue on Wireless ATM, October 1997

X.He,Tafazolli R, Evans BG, ”Priority-based Random Access Schemes for S-PCN“, IEE Electronics Letter, Vol.33 No.1, pp 25-27, 2 January 1997 Zhao W, Tafazolli R, Evans BG, ”Inter-Network Handover Performance Analysis in a GSM-Satellite Integrated Mobile Communication System”, IEEE Journal of Selected Communications (JSAC) Special Issue on Mobile Networks October 1997.

Lee J, Tafazolli R, Evans B G, “Erlang Capacity of OC-CDMA with imperfect Power Control” IEE Electronics Letters, Vol 33, No 4, pp. 259-261, 13 February 1997.

SEPARATE PUBLICATIONS Andrikopoulos I, Ors T, Matijasevic M, Leitold H, Posch R, “TCP throughput measurements within heterogeneous ATM local area networks” ATM Networks:Performance Modelling and Analysis, Vol.III, Chapman and Hall, London.

Cruickshank H, “Securing user, control and management planes in ATM networks”, National University of Singapore, May 97.

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SEPARATE PUBLICATIONS Ors T, Hadjitheodosiou M H, Sun Z, Evans B G, “ATM over VSAT networks using traditional bent-pipe or on-board processing Satellites” ATM Networks:Performance Modelling and Analysis, Vol.III, Chapman and Hall, London.

Taaghol P, Tafazolli R, Evans B G, “Performance Evaluation of an Adaptive Power Control Scheme in Measurement Based S-PCN Channel” IMSC’97, Pasadena California, USA, 16-18 June 1997.

Ors T, Sun Z, Evans B G, “A Meshed VSAT Satellite Network Architecture Using An On-board ATM Switch.” IEEE Int . Performance, Computing and Communications Conference 1997. IEEE, USA, 1997

Tateesh S, Atungsiri S, Kondoz A M, “Link Adaptation To Channel Interference Using Multi-rate Source and Channel Coding For CDMA Mobile Communications.” Proceedings of International Conference on Acoustics, Speech and Signal Processing (ICASSP) IEEE, Munich, Germany, April 1997.

CCSR PUBLICATIONS LIST FOR 1996 CONFERENCE PAPERS

PUBLICATIONS

Agius A A, Mahmoud M, Tafazolli R, Evans, B G, “QuadrafilarHelical Antennas for a Handheld Terminal in Satellite Personal Communication Networks (SPCN)” 5th Intl. Conf. on Satellite Systems for Mobile Com. & Navigation, IEE May 1996 Agius A A , Saunders S R , Evans B G, “Quadrifilar Helical Antenna (QHAI) Characteristics Of A Proposed Wire Antenna For An SPCN Handheld Terminal.” International Workshop On Mobile Communications ‘96, Greece, 19-21 September 1996. Andrikopoulos I, Ors T, Jones S P W, “Throughput Measurements for TCP/IP over AAL 5 in ATM LANs”, Twelfth UK Computer and Telecommunications Performance Engineering Workshop, University of Edinburgh, UK, 12th September 96. Andrikopoulos I, Ors T, Matijasevic, Leitold H, Jones S P W, Posch R, “TCP/IP Throughput Performance Evaluation for ATM Local Area Networks” 4th IFIP Workshop on Performance Modelling and Evaluation of ATM Networks. W. Yorkshire,UK Apostolas C, Tafazolli R, Evans B G, “Comparison Between Elimination Yield Non-Pre-Emptive Priority Multiple Access (EY-NPMA) and Dynamic TDMA (DTDMA)”Proceedings for PIMRC ‘96, Taipei, Taiwan 1996. Aziz H, “Effect of Total System Capacity due to Imperfect Power Control for Band sharing between CDMA based Non-Geostationary Satellite-PCNs”, The Seventh IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 96), Taiwan, Taipei, 15-18th October 1996.

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Coakley F P, Hadjitheodosiou M, “Networking with VSATS from Low Bit Rate Systems to ATM Service Provision” AIAA Conference, USA. February 1996. Cruickshank H, Sun Z, Velentzas S, A Proposal for Security Services in ATM Networks.Fourth Workshop on Performance Modelling and Evaluation of ATM Networks. Ilkley,W. Yorkshire. July 1996. Qi R, Coakley F P, Evans B G, “Low Complexity and Low Power Consumption Design for OBP Multicarrier DEMUX VLSI,” 16th AIAA International Communications Satellite Systems Conference, Washington, DC, USA, February 25-29, 1996. Qi R, Coakley F P, Evans B G, “A Reconfigurable Multistage Multicarrier DEMUX Architecture,” the 5th International Workshop on Digital Signal Processing Techniques Applied to Space Communications, Barcelona, Spain, September 25-27, 1996. Qi R, Coakley F P, Evans B G, “A Novel Pure Systolic Linear Phase FIR for High speedApplications,” the 7th International Conference on Signal Processing Applications & Technology, Boston, Massachusetts, USA, October 7-10, 1996. Qi R, Coakley F P, Evans B G, “Optimization of Complex Binary Tree Filter Bank Structure Using Multirate Signal Flow Graph Transformation,” the IEEE International Conference on Communication Systems, Singapore, November 25-29, 1996. Sadka A H, Eryurtlu F, Kondoz A M, “Source and Channel Coding for Mobile Multimedia Communications” COST 237 Workshop on Multimedia Telecommunications for Applications.25th November 1996. Barcelona, Spain.

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

Sadka A H, Eryurtlu F, Kondoz A M, “Aspects of error resilience for Block-Based Video Coders for Multimedia Communications”, IEE Colloquium on the future of Mobile Multimedia Communications, Savoy Place, London UK, December 1996. Saunders S, Evans B G, “The Spatial Correlation of Shadow Fading In Macrocellular Mobile Radio Systems” Proceedings IEE Colloquium on Propagation Aspects of Future Mobile Systems, IEE London 25 October 1996. Saunders S, Thomas H, “Control of Microcellular Re-use statistics using directional antennas in the presence of scattering” 46th IEEE Vehicular Technology Society Conference, April 28th May - 1st June 1996. Vol 3. pp 1685-1689. Sfikas G, Tafazolli R, Evans BG, “Hands-off Considerations in a Wireless ATM Environment”, International Workshop on Mobile Communications (IWMC), Thessaloniki, Greece, 19th Sept 1996. Sfikas G, Tafazolli R, Evans B G, “ATM Cell Transmission over the IEEE 802.11 Wireless MAC Protocol.” Personal, Indoor and Mobile Radio Communications PIMRC ‘96 Taiwan 1996. Shin S K, Sweeney P, “Evaluation of Efficient Trellis Methods for Soft Decision Decoding of Reed Solomon Codes” IEE Proceedings -Commun., Vol 143 No. 2 pp 61-67, April 1996. Sun Z, Ors T, Cruickshank H, Evans B G, “Implementation of ATM over satellite for broadband services” IEE Colloquium on ATM over Satellite, London, UK, 27 November 1996. Sun Z, Cruickshank H, Evans B G, “Theseus Broadband Networks for European Stock Exchange and Users.” IEEE ICCS/ISPACS 96, Singapore, November 1996 Taaghol Pouya, Tafazolli R, Evans B G, “Burst Reservation Multiple Access Techniques for the GSM/DCS and DECT Systems.” 7th IEEE International Symposium on Personal,Indoor and Mobile Communications, Taiwan. October 1996.

Taaghol Pouya, Tafazolli R, Evans B G, “Performance Optimisation of Packet Reservation Multiple Access Through Novel Permission Probability Strategies.” IEE Colloquia on Networking Aspect of Radio Comms. Systems. London, pp 8/1-8/5, March 1996 Tafazolli R, Evans B G, “Wide Area Mobility for DECT.” Globecom ‘96 London, UK. November 1996 Tafazolli R, Evans B G, “Interworking and Integration of the Inmarsat Standard-M with the Pan-European GSM System.” International Mobile Satellite Conference, Pasadena, CA, June 1993. Tateesh S, Atungsiri S, Kondoz A M, “Link Adaptive Multi-rate Coding Verification System for CDMA Mobile Communications” 1996 IEEE Global Telecommunications Conference GLOBECOM, London UK, November 1996. Tateesh S, Atungsiri S, Kondoz A M, “Link Adaptive Multi-rate Coding Verification System for CDMA Mobile Communications” Proceedings for 1996 IEEE Global Telecommunications Conference GLOBECOM, London UK, November 1996. Yaghmaie K, Kondoz A M, Atungsiri S, “Prototype Waveform Interpolation of Original Speech” 3rd Communication Networks Symposium. Manchester, UK July 1996. Yaghmaie K, Kondoz A M, Atungsiri S, “Prototype Waveform Interolation of Original Speech” Proceedings for 3rd Communication Networks Symposium. Manchester, UK July 1996.

PUBLICATIONS

Sadka A H, Eryurtlu F, Kondoz A M, Evans B G, “Performance Comparison of ITU H.261 and H.263 Video Coding Algorithms for Packet Switched Networks” Intl. Conference on Telecommunications. Istanbul, Turkey. April 1996.

Zhao W, Tafazolli R, Evans B G, “Inter Networking Signalling Load Analysis for GSM - Satellite Integration” EMPS ‘96, Rome, October 1996 Zhao W, Tafazolli R, Evans B G, “Inter-Network Signalling Load Analysis for GSM Satellite Integration.” Proceedings of the Second European Workshop on Mobile/Personal Satcoms. (EMPS ‘96) UK 1996. Cruickshank H S, “A Security System for Satellite Networks” IEE Conference on Satellite Systems for Mobile Communications and Navigation. London, UK. 13 -15 May 1996. Ghaheri Niri S, Tafazolli R, Evans B G, “Wide Area Mobility for DECT.” Globecom ‘96 IEEE Global Telecommunications Conference Proceedings. London, UK November 1996.

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Ghaheri Niri S, Tafazolli R, Evans B G, “Third Generation Personal Communications Network a Candidate Network for DIS” 15th DIS Conference/Workshop on the Interoperability of Distributed Interactive Simulations. Orlando September 1996

Ors T, Jones S P W, “An Adaptive Congestion Control Scheme For Networks Using Advanced Buffer Management.” IEEE Int. Conference On Communication Systems(ICCS). Singapore, Nov.1996.

He X, Tafazolli R, Evans B G, “Paging signalling in Non-GEO Satellite Mobile Systems” Fifth International Conference on “Satellite Systems for Mobile Communications and Navigation”, London, May 1996.

Ors T, Jones S P W, “Congestion Control For ABR Services In ATM LANS.” Eighth IEEE Workshop On Local And Metropolitan Area Networks. Potsdam, Germany, Aug 1996.

He X, Tafazolli R, Evans B G, “Call Processing Functions in the Integrated Satellite and GSM System” IEEE 46th Vehicular Technology Conference, Atlanta, USA, May 1996.

Ors T, Jones S P W, “Traffic management for ATM Local Area Networks using a Combined Preventive/Reactive Control Mechanism”, International Conference on Telecommunications 96, Bogazici, University, Istanbul, March 96.

He X, Tafazolli R, Evans B G, “An Optimised Signalling Architecture for a MEO/ICO Satellite System” AIAA 16th International Communications Satellite Systems Conference, Washington DC, USA, February 1996.

Otung I E, Evans B G, “Impact of Scintillation Fading on Satellite EHF Communications for Multimedia Mobile Services.” 2nd KA Band Utilization Conference, Florence, Italy, September 1996.

PUBLICATIONS

Husni E, Sweeney P, “Block Coded M-PSK Modulation Using Reed Solomon Codes” Fifth ESA International Workshop on Digital Signal Processing Techniques Applied to Space Communications. Barcelona, Spain, September 1996. Losquadro G, Jahn A, Lutz E, Paraboni A, Taaghol P, Tartara G, Evans B G, “SECOMS Demonstrators for Broadband Mobile Satellite Links at Ka and EHF Bands”, 2nd ACTS Mobile Communications Summit, Granada, Spain, November 1996. Lee J, Tafazolli R, Evans B G, “Capacity of the Overlapped Carriers Scheme in FD/FDS-CDMA” ISSSTA ‘96, Mainz, Germany. September 1996. Marinelli M, Perez-Leal R, Taaghol P, “SECOMS Satellite Characteristics for Mobile Multimedia Services”, ACTS Mobile Communications Summit, Granada, Spain, 27-29 November 1996. Meenan C, Tafazolli R, Evans B G, “A Low Earth Orbit Satellite Constellation For Personal Communication Networks” XXVth General Assembly of the International Union of Radio Science(URSI), Lille, France, August 1996. Ors T, Jones S P W, “Congestion Control for ABR Services in ATM LANS” 8th IEEE Workshop on Lans and MANs. Potsdam, Germany 25th August 1996. Ors T, Sun Z, Jones S P W, “ATM Networking with VSATs” 4th IFIP Workshop on Performance Modelling and Evaluation of ATM Networks, Ilkley, UK. July 1996. 36

Otung I E, Saunders S, Mahmoud M S, Parks M, Ahmed B, “Radio Propagation and Antennas Research at Surrey” 4th CEPIT Workshop. Florence, Italy September 1996 Otung I E, Comparative Evaluation of Rain and Scintillation Fading on Low-availability Ka-/EHF bands VSAT Satellite Systems. IEEE Africon ‘96 University of Stellenbosch, South Africa. September 1996. Otung I E, Mahmoud M S, “Statistics of Scintillation and the Structure of Atmospheric Turbulence.” XXVth General Assembly of the International Union of Radio Science (URSI) Lille, France, August 1996. Otung I E, Mahmoud M S, “Role of Tropospheric Scintilations in Satellite Communication Systems at Ka-band Frequencies and Beyond.” XXVth General Assembly of the International Union of Radio Science (URSI). Lille, France. August 1996. Parks M A N, Saunders S, Evans B G, “A Widespread Channel Model Applicable to Mobile Satellite Systems at L- and S-band” IEE Colloquium On Propagation Aspects Of Future Mobile Systems, IEE Savoy Place, London, 25 October 1996 Parks M A N, Saunders S, Evans B G, “Carrier to Multipath Characterisation and Prediction for Mobile Satellite Systems” EMPS ‘96 . Rome. 8-10th October 1996

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

Parks M A N, Saunders S, Evans B G, “A Wideband Channel Model Applicable to Mobile Satellite Systems at L- and S- band” IEE Colloquium on Propagation Aspects of future Mobile Systems - Proceedings. IEE Savoy Place, UK. October 1996. Parks M A N, Butt G, Buonomo S, Evans B G, “Wideband Propagation Measurements and Results at L and S-Bands for Personal and Mobile Satellite Communications” Fifth International Conference on Satellite Systems for Mobile Communications and Navigation, IEE Savoy Place, London. May 1996

Parks M A N, Butt G, Buonomo S, Evans B G, “Satellite Personal Communication Channel Characterisation at L and S-bands” First Communication Conference, Muscat. May 1996 Parks M A N, Butt G, Buonomo S, Evans B G, “Simultaneous Wideband Propagation Measurements Applicable to Mobile Satellite Communication Systems at L and SBands”16th International Communication Satellite Systems Conference, AIAA. February 1996.

JOURNAL PAPERS

Dyer C, Sims A, Underwood C, “Measurements of the Sea Environment from Sea Level to GEO using the Cream and Credo Experiments” IEE Transactions on Nuclear Science, Volume 43, Part 2. pp383 to 402 April 1996. Fagervik K, Jeans T G, “Low Complexity Bit By Bit Soft Output Demodulator.” IEE Electronics Letters, Vol 32, Part 11, pp. 985-987, May 1996. Guntch A, Tafazolli R, Giancristofaro D, Argenti F, Menolascino R, “Integrating GSM with new Satellite Systems”, Mobile Communications International, Issue 31, pp62-65, May 1996. Kweh T H, Eryurtlu F, Kondoz A M, “Rate control algorithm for block-based variable rate video encoders” IEE Electronics Letters, Vol.32, No.14, pp 1277-1278, July 1996. Lee J, Tafazolli R, Evans B G, “Effect of Adjacent Carrier Interference on SNR Under the Overlapping Carrier Allocation Scheme in FD/DS-CDMA” IEE Electronics Letters Vol.32, No. 3 p171-172, February 1996. Otung I E, “Prediction Of Tropospheric Amplitude On A Satellite Link .” IEEE Transactions On Antennas And Propagation, Vol.44, Part. 12, pp. 16001608. December 1996.

Qi R, Coakley F P, Evans B G, “Practical Considerations for Bandpass Sampling,”IEE Electronics Letters, Vol. 32, No.20, September 1996. Otung I E, Evans B G, “Tropospheric Scintillation and the Influence of Wave Polarisation” IEE Electronics Letters, Vol 32 Part 4, p307-308 February 1996 Sadka A H, Eryurtlu F, Kondoz A M, “Rate Control Feedback Mechanism for Packet Video Networks” IEE Electronics Letters, Vol.32 part 8. p716 to 717. April 1996. Saunders S, Evans B G, “Physical Model of Shadowing Probability for Land Mobile Satellite Propagation”, IEE Electronics Letters, Vol 32, Part 17, pp 1548-1589, 15 August 1996. Shah A, Atungsiri S, Kondoz A M, Evans B G, “Lossy Multiplexing of Low Bit Rate Speech in Thin Route Telephony.” IEE Electronics Letters, Vol.32, Part 2. p 95-97. January 1996.

PUBLICATIONS

Black A W, Kondoz A M, Evans B G, “Improved Pulsed Residual Excited Linear Prediction: A New Excitation for CELP Based Speech Coders” IEE Electronics Letters. Vol32 Part 6 p520-521, March 1996.

Shin S K, Sweeney P, “Evaluation of Efficient Trellis Methods for Soft Decision Decoding of Reed-Solomon Codes” IEE Proceedings - Communications, Vol.143, Part 2 p61-67. April 1996.Letters. Vol 32 Pt 1 pp 65 - 67 January 1996. Smith C J, Kondoz A M, Gaskell P S , Evans B G , “Subjective performance evaluation of tandemed full-rate GSM/ADPCM voice codecs” International Conference on Telecommunications, Istanbul, Turkey, pp 140143, April 1996.

Otung I E, “Scintillation Fade and Enhancement Duration on a 20 GHz Satellite Downlink” IEE

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JOURNAL PAPERS Tateesh S, Atungsiri S, Kondoz A M, “Impact of multi-rate source and channel coding on long term fading in CDMA mobile communication systems” International Conference on Telecommunications, Istanbul, Turkey, pp 750-753, April 1996.

Zhao W, Tafazolli R, Evans BG, “A Combined Handover Algorithm for Dynamic Satellite Constellations“, IEE Electronics Letters, Vol 32, No.7, pp.622-624, 28 March 1996.

Yeldener S, Kondoz A M, Evans B G, “Perceptually based modelling of excitation spectrum for the applications of multi-band LPC speech coding” International Conference on Telecommunications, Istanbul, Turkey, pp 148151, April 1996.

SEPARATE PUBLICATIONS Cruickshank H, “Implementation of ATM over Satellite Broadband Services” IEE Professional Group E9. Nov 96.

PUBLICATIONS

Ors T, Jones S P W, “An Adaptive Congestion Control Scheme For Networks Using Advanced Buffer Management.” IEEE Int. Conference On Communication Systems (ICCS). Singapore, Nov.1996. Ors T, Jones S P W, “Traffic management for ATM Local Area Networks using a combined Preventive/Reactive Control Mechanism”, International Conference on Telecommunications 96, Bogazici, University, Istanbul, March 96. Qi Rongang, Coakley F, Evans B G, “Optimisation of Complex Binary Tree Filter Bank Structure using multirate signal Flow Graph”, Conference Proceedings, IEEE ICCS/ISPACS 96, Singapore, Nov 96.

Smith C J, Black A W, Kondoz A M, “Improved Spectrum Efficiency by Source Compression”, Microwaves and RF 96 Conference Proceedings, Nexus Media Ltd, London 96. Sun, Z, Cruickshank H, Evans B G, “Theseus - Broadband Networks for European Stock Exchange and Users” IEEE International Conference on Communication Systems, Singapore, 25-29 November 1996. Sun Z, Ors T, Evans B G, ”Interconnection Of Broadband Islands Via Satellite Experiments on the Race II Catalyst Project”, Transport Protocols For High - Speed Broadband Networks Workshop, Globecom 96, 22 November 1996. Sun Z, Ors T, Cruickshank H, Evans B G, “Implementation of ATM over Satellite for Broadband Services” IEE Colloquium on ATM over Satellite, London, 27th November 1996.

CCSR PUBLICATIONS LIST FOR 1995 CONFERENCE PAPERS Agius A, Mahmoud M S, “A Simple World Wide Teleradiology System” TELEMED ‘95 International Conference on Telemedicine and Telecave Medicine in the Superhighway. Heathrow, London 8-9 November 1995. Allery M N, Price H E, Ward J W, da Silva Curiel R A, “Low Earth Orbit Microsatellites for Data Communications Using Small Terminals.” Proceedings to 10th IEE International Conference on Digital Satellite Communications, Vol 2, pp. 457-465, Brighton, May 1995.

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Apostolas C, Tafazolli R, Evans B G, “Wireless ATM LAN.” Proceedings to 6th IEEE International Symposium on Personal, Indoor & Mobile Communications (PIMRC’95), pp. 773-777, Toronto, Canada, September 1995. Atkinson I A, Kondoz A M, Evans B G, “Time Envelope LP Vocoder: A New Coding Technique at Very Low Bit-Rates.” Proceedings to EUROSPEECH ‘95, pp. 241-244, Madrid, September 1995. Atkinson I A, Kondoz A M, Evans B G, “Time Envelope Vocoder, A Natural Sounding Speech Coding Algorithm Operating at 1.6 KBits/Sec.” Fifth IEE Conference on Telecommunications, IEE, Brighton, 26-29 March 1995.

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

Bjelajac B, Cohen M, Fantacci R, Huggins G, Sammut A, “Dynamic Channel Allocation Schemes for Satellite UMTS.” Proceedings to RACE Mobile Telecommunications Summit, Vol 2, pp. 313-318, Cascais, Portugal, November 1995. Black A, Atkinson I, Kondoz A M, Evans B G, “High Quality 14.2kb/s Wideband Speech Coder”. EUROSPEECH ‘95, Madrid, September 1995. Black A, Atkinson I, Kondoz A M, Evans B G, “High Quality 14.1kb/s Wideband Speech Coder.” Proceedings to EUROSPEECH ‘95, pp. 45-48, Madrid, September 1995. Black A, Kondoz A M, Evans B G, “High Quality Low Delay Wideband Speech Coding at 16KBits/Sec.” 2nd Int. Workshop on Mobile Multimedia Communications, Hewlett Packard, Bristol University, 11 April 1995. Butt G, Parks M A N, Evans B G, “Narrowband and Wideband Characterisation of Satellite Mobile/PCN Channel.” IMSC’95, Ottawa, Canada, June 1995. Butt G, Parks M A N, Evans B G, “Measurements & Modelling of Wireless Channel for Satellite Mobile/Personal Communication Systems.” 10th Int. Conf. on Digital Satellite Communications, IEE, Brighton, May 1995. Butt G, Parks M A N, Evans B G, “Modelling the Mobile Satellite Channel for Communication System Design.” Int. Conf. on Antennas & Propagation, IEE, The Netherlands, April 1995. Butt G, Parks M A N, Evans B G, “Modelling the Mobile Satellite Channel for Communication System Design.” Int. Conf. on Antennas & Propagation, IEE, The Netherlands, April 1995. Butt G, Parks M A N, Evans B G, “Channel Models for Mobile/Personal Satellite Communication Systems.” Proceedings of 1st European Workshop on Mobile/Personal Satcoms, EMPS’95, pp. 251-262, London, 1995. Coakley F P, Yim W H, “A Hybrid CDMA Scheme and Demodulator Structure for Ka-Band Operation.”10th Int. Conf. on Digital Satellite Communications, Brighton, 15 May 1995.

Coakley F P, Malinowski P, “Fault Tolerant On-Board Switches for ATM.” 10th Int. Conf. on Digital Satellite Communications, Brighton, 15 May 1995. Cullen C, Sammut A, Tafazolli R, Evans B G, “Networking & Signalling Aspects of a Satellite Personal Communications Network.” Proceedings of the 1st European Workshop on Mobile/Personal Satcoms, EMPS’95, pp. 202-222, London, 1995. Danesfahani G R, Jeans T G, “Self-Noise Cancellation of the Modified Mueller and Müller Algorithm.” 3rd Int. Symposium on Communication Theory and Applications, IEEE, Ambleside, July 1995. Eryurtlu F, Kondoz A M, Evans B G, “Predictive Entropy Coding of Gain-Shape VQ Parameters.” Proceedings for 1995 Int. Conf. on Acoustics, Speech & Signal Processing, pp. 2515-2518, Detroit, May 1995. Eryurtlu F, Sadka A H, Atungsiri S, Kondoz A M, Evans B G, “Integrated Speech and Video Coding for Mobile Audio-Visual Communications.” 2nd Int. Workshop on Mobile Multimedia Communications,pp 93-97, Hewlett-Packard, Bristol University, 11 April 1995. Evans B G, Zhao W, Tafazolli R, “Interworking Procedures Between Cellular Networks & Satellite Systems.” Proceedings of the 1st European Workshop on Mobile/Personal Satcoms, EMPS’95, pp. 123-141, London, 1995. Hadjitheodosiou M H, Coakley F P, “Adaptive Multiple Access Protocols for VSATs Providing Voice/Data Services & ATM Interconnection.” 10th Int. Conf. on Digital Satellite Communication Networks Symposium (IEEE) Manchester 1995Communications, IEE, Brighton, May 1995

PUBLICATIONS

Atungsiri S A, Kondoz A M, Evans B G, “Comparative Study of Two CELP Codecs for Enhanced Full Rate GSM Applications.” Proceedings to EUROSPEECH ‘95, pp. 703-706, Spain, September 1995.

He X, Tafazolli R, Evans B G, “Study of CRP and Capture Probability in Slotted Aloha RACH of NGEO Satellite System.” IMSC ‘95, Ottawa, Canada, June 1995. Ho H P, Sweeney P, “Soft Decision Decoding of Reed Solomon Codes using the Dorsch Algorithm”, Proceedings of 5th IMAConference on Coding and Cryptography, December 1995. Mahmoud M S, Evans B G, “Radiowave Amplitude Scintillation & Applications to Remote Sensing of the Atmosphere.” 12th UK National Radio Science Colloquium, London, July 1995.

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Ors T, Jones S P W, “Performance Optimization of ATM Input Control using Multiple leaky-Buckets” Third IFIP Workshop on Performance Modelling and Evaluation of ATM Networks. (IFIP) Yorkshire July 1995. Ors T, Jones S P W, “Congestion Control for ATM LANs using Reactive and Preventive Control” Second Communication Networks Symposium (IEEE) Manchester July, 1995. Otung I E, Mahmoud M S, “Data Processing Techniques in Radiowave Propagation.” 12th UK National Radio Science Colloquium,London, July 1995. Otung I E, Mahmoud M S, Norbury J R, “Observations of Ka-Band Tropospheric Scintillation on a Moderate-Elevation EarthSpace Path.” 12th UK National Radio Science Colloquium, London, July 1995.

PUBLICATIONS

Otung I E, Goddard J W F, “Radiowave Amplitude Scintillation in Precipitation-filled Random Media.” Proceedings to the “Progress in Electromagnetics Research Symposium” (PIERS), pp. 532, Seattle, USA, July 1995. Otung I E, Mahmoud M S, Norbury J R, “Differential Amplitude Scintillation in a Ka-Band Satellite Link.” Int. Conf. on Antennas & Propagation, IEE, The Netherlands, April 1995.

Otung I E, Mahmoud M S, Evans B G, “Radiowave Amplitude Scintillation & Applications to Remote Sensing of the Atmosphere.” 12th UK National Radio Science Colloquium, London, July 1995. Parks M, Butt G, Evans B G, “Propagation Aspects in Satellite Mobile/PCN System Design.” Proceedings to RACE Mobile Telecommunications Summit, Vol 2, pp. 535541, Cascais, Portugal, November 1995. Sadka A H, Eryurtlu F, Kondoz A M, Evans B G, “A Method for Controlling the Bit Rate of an H.261 Video Stream for Multimedia Communications.” 2nd Communication Networks Symposium, Manchester, July 1995. Sadka A H, Eryurtlu F, Kondoz A M, Evans B G, “Packetisation of Speech and Video Signals for Multimedia Communications.” Int. Conf. on Multimedia Communications: The Information Age, SCS Europe BVBA, Southampton, April 1995.

JOURNAL PAPERS Atkinson I A, Kondoz A M, Evans B G, “Pitch Detection of Speech Signals Using Segmented Autocorrelation.” IEE Electronics Letters, Vol 31, Part 7, pp. 533-535, March 1995. Atkinson I A , Kondoz A M, Evans B G, “1.6kbits/sec LP Vocoder Using Time Envelope.” IEE Electronics Letters, Vol 31, Part 7, pp. 517-519, March 1995. Atkinson I A, Kondoz A M, Evans B G, “Time Envelope Vocoder A New LP Based Coding Strategy for Use at Bit Rates of 2.4kb/s and Below.” IEE Journal on Selected Areas in Communications, IEE, Vol 13, Part 2, pp. 449-457, February 1995. Danesfahani G R, Jeans T G, “Optimisation of Modified Mueller and Muller Algorithm.” IEE Electronics Letters, Vol. 31, Part 13, pp. 1032-1033, June 1995.

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Otung I E, Subramaniam R, Willis M J, Mahmoud M S, “Rain Attenuation Statistics of Ka-Band EarthSpace Path.” Int. Conf. on Antennas & Propagation, IEE, The Netherlands, April 1995.

Eryurtlu M O F, Kondoz A M, Evans B G, “Very Low Bit Rate Segmentation Based Video Coding using Contour and Texture Prediction.” IEE Proceedings - Vision, Image & Signal Processing, Vol 142, No. 5, pp. 253-261, October 1995.

Eryurtlu M O F, Atungsiri S A, Kondoz A M, Evans B G, “Entropy Coding of ITU G.728 Speech Parameters for Low Bit Rate Audiovisual Communications.” IEE Electronics Letters, Vol. 31, Part 15, pp. 1213-1215, July 1995. Kondoz A M, “Pulse Residual Excited Linear Prediction.” IEE Proc. in Vision, Image & Signal.Processing, Vol. 142, Part 2, pp. 105-110, March 1995. Kondoz A M, Horos J, Evans B G, Suddle M R, “Pulsed Residual Excited Linear Prediction.” Proc. of Vision, Image and Signal Processing, IEE, Vol 142, Part 2, pp. 105-110, April 1995. Meenan C, Sammut A, Tafazolli R, Evans B G, “Deligo: Repetitive Ground Track 100% DualDiversity LEO Satellite Constellation for S-PCN.” IEE Electronics Letters, Vol. 31, Part 17, pp. 1407-1408, August 1995.

CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

Otung I E, “New Equations for the Terminal Velocity of Precipitation Droplets in a Standard Atmosphere”Journal of Electromagnetic Waves and Applications Vol.9. Part 10. 1995 pp 1241 - 1247.

Shin S K, Atungsiri S A, Kondoz A M, Evans B G, “Trellis Decoding of Reed-Solomon Codes in Low Bit Rate Speech Communications.” IEE Electronics Letters, Vol. 31, Part 16, pp. 1331-1332, August 1995.

Otung I E, Mahmoud M S, Norbury J R, “Radiowave Amplitude Scintillation Intensity: Olympus Satellite Measurements & Empirical Model.” IEE Electronics Letters, Vol 31, Part 21, pp. 1873-1874, October 1995.

Shin S K, Sweeney P, “Efficient Sequential Decoder for Reed Solomon Codes.” International Journal on Electronics, Vol. 79, Part 1, pp. 1-6, July 1995.

Otung I E, Evans B G, “Short Term Distribution of Amplitude Scintillation on a Satellite Link.” IEE Electronics Letters, Vol. 31, Part 16, pp. 13281329, August 1995. Otung I E, Mahmoud M S, Evans B G, “ Dual Frequency Scintillation Measurement for Remote Sensing” IEE Electronics Letters, Volume 31, Part 23, Pages 1972-1973. 9 November 1995.

Sun Z, Coakley F P, Evans B G, “Satellite ATM for Broadband ISDN.” Telecommunication Systems, Vol. 4, pp. 119131, April 1995. Sweeney P, “Cyclic Block Codes Definable over Multiple Finite Fields”, IEE Electronics Letters, Vol 3 No.5 pp 344-346, 2 March 1995.

PUBLICATIONS

Otung I E, Evans B G, “Short Term Distribution of Amplitude Scintillation on a Satellite Link.” IEE Electronics Letters, Vol. 31, Part 16, pp. 13281329, August 1995.

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CENTRE FOR COMMUNICATION SYSTEMS RESEARCH

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