802.11AC MIGRATION GUIDE. Aruba Migration Guide

Aruba Migration Guide 802.11AC MIGRATION GUIDE 802.11ac Aruba Migration Guide Table of Contents Introduction 3 802.11AC basics 3 Why 802.11ac...
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Aruba Migration Guide

802.11AC MIGRATION GUIDE

802.11ac

Aruba Migration Guide

Table of Contents Introduction

3

802.11AC basics

3

Why 802.11ac?

3

802.11ac technology overview

4

Backward compatibility

4

RF spectrum

4

Multistation MAC throughput > 1 Gbps

5

256 QAM

5

Wider channels

5

More spatial streams

5

Downlink multi-user MIMO

6

Pros of 802.11ac

6

Cons of 802.11ac

6

Strategy and planning for 802.11ac migration

6

Site planning basics

6

Planning process

6

Minimum requirements and actions to implement 802.11ac

7

Aruba recommendations for 802.11ac migration

8

General

8

Capacity

8

RF planning

8

Installation

8

Wireless RF coverage considerations and questionnaire

9

Summary

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802.11ac

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Introduction Wi-Fi has become such an amazingly successful technology because it has continuously advanced while remaining backwards compatible. The current state-of-the-art Wi-Fi is known as Wi-Fi CERTIFIED n or 802.11n. 802.11n has become popular because it improves performance. As 802.11n has become a standard interface on PCs, tablets and smartphones, the applications used by these devices have continued to progress. Mobile technology has encountered the next frontier – video. Whether delivering YouTube to smartphones or moving HDTV signals around the office or home, video has become a significant driver of network traffic, chiefly because it requires one or two orders of magnitude more bandwidth than other IP services. Now the 100 Mbps or 200 Mbps rates enabled by 802.11n, breakthrough figures that put it on a par with 10/100 Mbps Ethernet just a few years ago seem barely adequate for some emerging video applications. The next step in improving performance is 802.11ac, with speeds up to 1.3 Gbps in 2013 and much higher by 2015. The purpose of this paper is to provide a level of guidance towards the migration to 802.11ac.

802.11ac basics Why 802.11ac? On average, there are 40 mobile apps are on every smartphone and this number is increasing on a daily basis. Some 310 billion mobile app downloads are expected by Q1/2016, and 70% of smartphones will be 802.11acready by Q2/2015. And let’s not forget about tablets – they consume 3.4-times more traffic compared to a smartphone on average. Networks must contend with this higher demand. Enterprises have also grown more reliant on higher bandwidth, latency-sensitive applications. For example, virtual desktop infrastructures (VDI) are characterized by bursty, delay-sensitive traffic because processing occurs in the data center instead of locally. HD video-capable mobile devices are proliferating. And users increasingly rely on them for fast and efficient mobile telepresence. Collaborative programs like Microsoft Lync, Apple FaceTime, WebEx and Citrix GoToMeeting create two-way video traffic across the network. The use of podcasting and streaming has also skyrocketed. It is therefore only natural to see a huge increase in the consumption of multimedia on mobile devices in the residence hall. Due to the pervasiveness of wireless in some environments, the smart classroom has now become virtualized, which allows its capabilities to be delivered anywhere there is capacity to receive it. The 80/20 rule for download and upload direction no longer exists. New app behavior has completely transformed traffic patterns. For example, smartphones synchronize all photos to cloud-based storage when a user walks into a building and connects to a Wi-Fi network. Mobile apps are constantly updated in the background over the Wi-Fi or cellular network without IT or user intervention. Apps download new advertisement screens and software updates, issue stay-alive pings, and multiple devices continuously authenticate and synchronize while roaming. IPTV and other locally-generated video streaming are focused on the residence hall as well. The cable TV infrastructure is aging and campuses do not have the resources required to maintain separate networks. Combine that with the demand to propagate locally generated content, and many campuses are replacing their cable systems with some variant of IPTV.

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802.11ac

Aruba Migration Guide

Digital signage is receiving more play as well. Originally, digital signage was conceived as a static medium to replace paper bulletin boards in residences halls and other campus venues. Now, digital signage is used to stream multimedia news channels and other locally generated video clips along with their static information components. More non-multimedia residential hall services are moving to IP as a transport. These services can impact the performance of latency-sensitive multimedia applications in those environments. Examples include physical security systems (door locks and video surveillance), vending machines, parking enforcement devices, and HVAC and other sensor-based systems. 802.11ac is a set of physical layer enhancements for higher throughput in the 5-GHz band, chiefly with video in mind, and to achieve this it extends the techniques pioneered in 802.11n: More antennas, wider channels, more spatial streams - along with a number of new features to boost throughput and reliability. We can think of 802.11ac as the next step after 802.11n, along the path running from 802.11b to 802.11a/g, then 802.11n, and now 802.11ac. And it is likely to be introduced along with related amendments to 802.11 including video-related improvements in 802.11aa (video transport streams) and 802.11ad (very high throughput, short-range at 60 GHz). In the same way that chip vendors have now switched production almost completely to 802.11n, even for low-cost, low-power applications such as smartphones, we can confidently predict that 802.11ac will become the de-facto standard for 5-GHz Wi-Fi equipment in a few years.

802.11ac technology overview 802.11ac brings about some very significant changes both in terms of RF spectrum utilization as well as technology features that will greatly enhance performance. Some of these changes will occur immediately while others will occur further down the road. Some of the key changes are listed here. For a more detailed look at 802.11ac please refer www.802-11ac.net.

Backward compatibility All 802.11ac access points (APs) will be backwards compatible with 802.11a/b/g/n. This will allow for a gradual migration away from these legacy devices to 802.11ac on a more time-manageable schedule. Note that not all of the features from 802.11ac will be available for use with these legacy devices.

RF spectrum 802.11ac will only operate in the 5-GHz radio spectrum country-specific restrictions apply): • 5.150 to 5.250 GHz • 5.250 to 5.350 GHz • 5.470 to 5.725 GHz • 5.725 to 5.850 GHz

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802.11ac

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Multistation MAC throughput > 1 Gbps Figures1 show the theoretical link rates for 802.11ac. Actual rate links will vary greatly based on external factors such as distances to/from AP, signal-to-noise ratio (SNR) and proximity to other radio devices.

Channel Transmit – bandwidth receive antennas

Modulation and coding etc.

Typical client scenario

Throughput (individual link rate)

Throughput (aggregate link rate)

80 MHz

1x1

256-QAM 5/6, short guard interval

Smartphone

433 Mbps

433 Mbps

80 MHz

2x2

256-QAM 5/6, short guard interval

Tablet, PC

867 Mbps

867 Mbps

160 MHz

1x1

256-QAM 5/6, short guard interval

Smartphone

867 Mbps

867 Mbps

160 MHz

2x2

256-QAM 5/6, short guard interval

Tablet, PC

1.73 Gbps

1.73 Gbps

160 MHz

4x Tx AP, 4 clients of 1x Rx

256-QAM 5/6, short guard interval

Multiple smartphones

867 Mbps per client

3.47 Gbps

160 MHz

8x Tx AP, 4 clients with total of 8x Rx

256-QAM 5/6, short guard interval

Digital TV, set-top box, tablet, PC, smartphone

867 Mbps to two 1x clients 1.73 Gbps to one 2x client 3.47 Gbps to one 4x client

6.93 Gbps

160 MHz

8x Tx AP, 4 clients of 2x Rx

256-QAM 5/6, short guard interval

Multiple set-top boxes, PCs

1.73 Gbps to each client

6.93 Gbps

Figure 1. 802.11ac theoretical link rates

256 QAM 802.11ac continues to exploit the limits of modulation and coding techniques, this time with the leap from 64-quadrature amplitude modulation (QAM) to 256-QAM. It is important to note that the range for maximum 802.11ac rates will most likely not be the same as that of 802.11n owing to the fact that 256-QAM requires a higher SNR (minimum 6 dB higher) to decode the 802.11ac signal. 256-QAM, rate 3/4 and 5/6 are added as optional modes. For the basic case of one spatial stream in a 20-MHz channel, this extends the previous highest rate of 802.11n from 65 Mbps (long guard interval) to 78 Mbps and 86.7 Mbps respectively, a 20% and 33% improvement. Note that 802.11ac does not offer every rate option for every MIMO combination.

Wider channels Initially 802.11ac will use channel widths of 20, 40, and 80 MHz. Future versions of 802.11ac will allow for 160-MHz channel widths as well.

More spatial streams 802.11n defines up to four spatial streams, although there are to date no Wi-Fi chipsets and APs using more than three streams. 802.11ac extends this to eight spatial streams. Aruba Networks, Inc.

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Downlink multi-user MIMO Thus far, all 802.11 communication has been point-to-point (one-to-one) or broadcast (one-to-all). With future versions of 802.11ac, a new feature allows an AP to transmit different streams to several targeted clients simultaneously.

Pros of 802.11ac • The maximum speeds/bandwidth supported by 802.11ac will vary from 433 Mbps to 6.93 Gbps. • A single 802.11ac radio can accommodate more users/Wi-Fi devices than previous standards (802.11a/b/g/n). • 802.11ac will support higher data rate over longer distances. This is due to the more aggressive error correction codes supported by 802.11ac as well as a quieter RF environment. • 802.11ac uses beamforming to improve SNR. This results in better wireless throughput. • 802.11ac uses 256-QAM that provides a 33% increase in throughput over 64-QAM used in 802.11n. • Future versions of 802.11ac will use multi-user MIMO (MU-MIMO) that allows APs to transmit single/multiple streams to multiple clients at the same time. This allows for better efficiencies for where a large number of lowconfiguration Wi-Fi devices, such as smartphones, need to connect. • Since 802.11ac operates in the 5-GHz spectrum, there is lower interference from other wireless devices. There are more non-overlapping channels (23 20-MHz channels) in 5 GHz, which provides for greater design flexibility.

Cons of 802.11ac • Existing 802.11n APs cannot be upgraded to 802.11ac. That means that all the APs and client adapters in an organization will require a hardware replacement to 802.11ac compliant products to fully implement an 802.11ac network. • The advanced features of 802.11ac won’t be available until 2015. • For full capacity operation, 802.11ac APs require 802.3at PoE+ enabled access layer switches when the APs are powered using power-over-Ethernet.

Strategy and planning for 802.11ac migration Site planning basics This section provides an overview of the tools needed to conduct a successful site survey and plan the deployment of an Aruba WLAN. It requires an understanding of RF and WLAN technology, terminology, and industry standards. An Aruba WLAN should be planned by an engineer who successfully has passed the CWNP examination for certified wireless network administrator (CWNA), Aruba Certified Mobility Professional (ACMP) or equivalent.

Planning process Before you deploy a wireless network, you must evaluate the environment. When you understand the environment, you can properly select Aruba APs and antennas and determine their placement for optimal RF coverage. Perform an initial environment evaluation: You must know what to look for and questions to ask to effectively determine the environment type and the appropriate deployment type. Select the proper APs and antennas for the deployment: You must understand Aruba APs and antenna types to determine the products that are best suited for the environment and to provide optimal performance and RF coverage. Enter the collected and determined information into VisualRF Plan: The VisualRF Plan is the Aruba predeployment site-planning tool. In most instances, you can perform a standard deployment based on the VisualRF Plan output without a physical site survey.

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This is called a virtual site survey. For complex deployments, you can use VisualRF Plan to generate a basic foundation for planning. But then you should visit the site to verify AP location and signal coverage. Conduct a physical site survey (if applicable): To properly characterize the RF propagation of a given facility, conduct a passive and/or active physical site survey. When you select AP locations, you must identify the worstcase challenges in the installation environment. A walk-through is crucial to effectively plan a WLAN deployment in a complex environment. Make adjustments to VisualRF Plan (if applicable): After conducting a physical site survey, the RF propagation assessment will help guide you toward the best choice of actual AP locations. Aside from the general environment, physical obstructions such as poles, lights, ventilation, and cable runs should be considered. Change the floor plan to adjust for these findings. Install the selected APs and external antennas (if applicable): Installation guides are available with the products and on the Aruba support site. Configure the APs: Configure the APs according to the best practices outlined in Aruba’s free Validated Reference Design (VRD) guides. Note: This guide describes the first seven steps in the process. AP mounting instructions and antennas are available with the product or on the Aruba support site. AP configuration information is in the base design VRD guides.

Minimum requirements and actions to implement 802.11ac • Ensure minimum 1 Gbps uplink ports available per AP. • Ensure uplink ports support 802.11at PoE. 802.11af can be used, but performance will be significantly reduced. • Conduct an RF survey. -- Compare minimum receive sensitivity requirements to Figure 2 below:

-40 -45

Sensitivity dBm

-50

X

-55

X -60

Minimum sensitivity (40 MHz PPDU) (dBm)

X

Minimum sensitivity (80 MHz PPDU) (dBm)

X

X

X

-65 -70 -75

X

X

Minimum sensitivity (20 MHz PPDU) (dBm)

X

Minimum sensitivity (160 MHz or 80+80 MHz PPDU) (dBm)

X

X

-80 -85

1/2 BPSK

1/2 QPSK

3/4 QPSK

1/2 16-QAM

3/4 16-QAM

2/3 64-QAM

3/4 64-QAM

5/6 64-QAM

3/4 256-QAM

5/6 256-QAM

Required receive sensitivity for different modulation and coding rates

Figure 2. Required Receive Sensitivity

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Aruba recommendations for 802.11ac migration General The vast majority of customers that deployed WLANs based on 802.11a/b/g technologies are currently going through a refresh cycle to transition to 802.11ac. These same customers often wonder why they can’t simply replace their existing APs with new APs. The answer is that it depends on the original AP density and the types of applications and devices that will use the new network.

Capacity For capacity planning purposes, plan on upload speeds being equal to download speeds. In addition: • Plan for at least three devices per user: A laptop, a tablet, and a smartphone. The number of devices per user also has ramifications in the design of VLANs and subnets. Consider if all devices will be active simultaneously, which also impacts AP density. • 20-30 devices per radio (40-60 per dual-radio AP). • Use Aruba Adaptive Radio Management™ (ARM) to automatically control channel and power settings and maximize client connectivity in the deployment. • Capacity-based deployment for all office and education settings. • 802.3at power on edge switches using Aruba S3500 and S2500 Mobility Access Switches. • Mobility Controllers running ArubaOS 6.3 or greater will support 802.11ac, and network performance will vary depending on the controller model. Normal standalone master controller scaling still applies when migrating to 802.11ac. For maximum capacity, the 7200 series Mobility Controller is highly recommended. • For high-density bandwidth needs, the Aruba 220 series of 802.11ac APs support link aggregation. Two Ethernet ports can also provide redundancy across different closet switches if link aggregation is not used.

RF planning Virtual survey should be performed with the VisualRF Plan and compared with the current deployment. The new survey provides a comparison of the current deployment to a more optimal 802.11ac network in the same space to determine if one-for-one replacement is viable, although one-for-one replacement is not recommended. Environments that are more complex are more likely to require a physical site survey. In enterprise networks, the five available 80-MHz channels, of which three require dynamic frequency selection (DFS), should be sufficient for overlapping APs to provide contiguous coverage. Three-channel plans have been used in the 2.4-GHz band for years, although some networks will have reasons to prefer a higher number of smaller-width channels. Although the widespread adoption of 160-MHz channels is unlikely, special applications that use this option will likely emerge.

Installation Upgrading from 802.11a/b/g to 802.11ac Comparing the highest 802.11ac rate (MCS9) with the highest 802.11n one (MCS7): • The minimum SNR needed to decode the 802.11ac signal is 6 dB higher than the 802.11n signal. • To support the higher modulation depth, the maximum transmit power levels for the 802.11ac signal is 2 dB lower. • The noise in an 80-MHz channel is 3 dB higher than in a 40-MHz channel.

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As a result: • In a channel with the same bandwidth, 802.11ac MCS 9 needs a 6 dB higher SNR than 802.11n (36 vs. 30). • The highest 802.11ac VHT80 rate will need a signal of 9 dB more than the highest 802.11n HT40 rate. Mixing 802.11ac and 802.11a/b/g/n APs In some deployments, 802.11ac APs will be rolled out in phases. In the past, some organizations have chosen to deploy mixed environments with the newer 802.11n APs mixed with legacy 802.11a/b/g APs. As most clients move through the network, they expect to see the same channel width and modulation types in use. Roaming from an 802.11ac 40- or 80-MHz channel to an 802.11a/g 20-MHz channel causes some devices to become stuck to the higher speed AP. In some cases, devices disconnect themselves from the network, which requires manual intervention by the user. There is also a conflict between new RF management techniques like ClientMatch and the older band steering giving an unpredictable client experience. When taking a phased approach to 802.11ac deployment: • If going from 802.11n to 802.11ac: Upgrade one floor or building at a time. • If going from 802.11a/b/g to 802.11ac: Upgrade one building at a time. This approach gives devices in that area the best chance of remaining connected to the network and provides a better user experience.

Wireless RF coverage considerations and questionnaire Answers to these questions help you to determine the proper Aruba AP type, prepare for the site survey, and plan appropriately for the deployment. Which RF bands will be used, 2.4 GHz or 5 GHz? Without a very good reason, always plan to use both bands to handle increases in client density. What channel width – 20 MHz vs. 40 MHz vs. 80 MHz – will be used in each band? Typically, 20-MHz channels are used in 2.4 GHz, and 40-MHz and 80-Mhz channels are used in the 5-GHz band. In dense deployments, speed may be traded off for capacity in the 5-GHz band by reducing to a 20- or 40-MHz channel. Will voice-over-Wi-Fi be used? This answer will affect your planning for roaming and AP signal strength calculations. For example, with voice-overWLANs, signal strength and quality of service (QoS) are key factors – more so than in the case of data only. Will multicast video over Wi-Fi be used? Use of roaming video has a similar effect as voice. In addition, video will require a consistent bandwidth and low latency. For example, for lightly compressed video (Motion JPEG2000) requires a constant bit rate of 150 Mbps. Will real-time location services (RTLS) be used? Consider deploying air monitors around the building perimeter to help with location accuracy. This deployment ensures that all clients are within the triangulation zone.

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How many devices will each user have? Aruba recommends that you plan for at least three devices per user: a laptop, a tablet, and a smartphone. The number of devices per user also has ramifications in the design of VLANs and subnets. Consider if all devices will be active simultaneously, which also impacts AP density. What is the maximum number of devices desired for each AP? Typically Aruba recommends 20-30 devices per radio (40-60 per dual-radio AP). What applications will be in use at the site, both presently and in the future? Bandwidth requirements help determine coverage vs. capacity requirements. Are any floor plan images available? VisualRF Plan supports direct importation of JPEG, GIF, PNG, PDF, and CAD (.dwg and .dwf) files for floor plan formats. What do you do if DFS channels are being considered? Ensure that the most commonly used devices in the network support DFS.

Summary 802.11ac takes all the techniques the Wi-Fi industry has learned up to 802.11n, and extends them. It’s likely that in a few years, Wi-Fi will be synonymous with 802.11ac. The significant improvements attained by migrating to 802.11ac are: • Higher throughput • Higher capacity • Wider channels • Lower latency • More spatial streams • More efficient use of 5-GHz RF spectrum • Higher-rate modulation • Higher-level MIMO

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