Perimeter-Based High Performance Home Security System Vishnu Chunduru Software Engineer 3HT Technologies Reston, Virginia [email protected]

Nary Subramanian Dept of Computer Science University of Texas at Tyler Tyler, Texas [email protected]

Abstract Homes of the future are expected to be “digital” homes wherein almost all aspects of a home could be controlled using advanced computer technology. One important component of the digital home is the home security system (HSS) that helps to monitor and control various elements related to home security. HSS may be classified into different types including passive systems (PS), phone based systems (PBS), web-based systems (WBS), and hardware-based systems (HBS), where each system differs in performance, controllability, security, and cost. For the success of an HSS the most important characteristics, or non-functional requirements, are performance and security – however, it is almost impossible to have both high security and high performance at the same time. In order to achieve both these non-functional requirements at the same time we adopted the concept of perimeter security from the fields of homeland security and network security to HSS wherein different areas of the house are divided into perimeters and each perimeter uses a different type of HSS to provide security. Preliminary results indicate that both high security and high performance can be achieved using the perimeter-based approach; however, this achievement comes at the cost of high price-tag for the development and maintenance of the system, and an increase in the overall complexity of the system.

1. Introduction Homes of the future are expected to be “digital” homes [1] wherein almost all aspects of a home could be controlled using advanced computer technology – the homeowner can turn the stove on or off, play her favorite music on the entertainment center, and check the identity of the person ringing the door bell, each with a touch of the button. One important component of the digital home is the home security system (HSS) [2, 3] that helps to monitor and control various elements related to home security. HSS incorporates sensors, actuators, alarms, controllers, gateways, and servers, to deliver a highly personalized and effective home security. But the best part of HSS is that both monitoring and control can be done remotely by a hand-held device such as a laptop, PDA, cell phone or even a telephone. Thus, for example, an open garage door may be detected and closed, both remotely, using, for example, the cell phone instead of making a trip back to the

house for just confirming if the garage door is closed. Based on our research we have classified HSS into four types: passive systems (PS), phone based systems (PBS), web-based systems (WBS), and hardware-based systems (HBS). In a PS the monitoring is remote while control is manual or physical, in a PBS the monitoring and control can be done using the public telephone network, in a WBS the monitoring and control is done over the Internet, while in a HBS the monitoring and control is done in hardware. Each of the different types of HSS uses a specific configuration of sensors, actuators, controllers, and the other elements, all interlinked in a network using protocols and software. High security can be achieved by exploiting the security features available in the elements of the HSS, while good performance is achievable by ensuring proper interworking of the different elements. However, security and performance, both being non-functional requirements, often seem to have conflicting relationship with each other – it is almost impossible to have both high security and high performance at the same time. But this very requirement seems to be important for the success of any HSS. For example, let the swimming pool at home be rigged with motion sensors so that if anyone approaches within three feet of the pool the sensors are tripped and the alarm sounded; when a child or pet walks toward the pool, the HSS will trigger the alarm but the delays in the alarm reporting and confirmation may render the alarm useless to save the child or pet from possible serious injury – here performance has been compromised at the expense of high security. In order to simultaneously achieve high performance and security, we adopted the concept of perimeter security from the fields of homeland security [4] and network security [5] for HSS. We defined three security perimeters – perimeter 1 (P1) encircles those areas in the home that need maximum security including swimming pools, bedrooms, home offices, and “valuables” room; perimeter 2 (P2) includes the remaining areas inside the house; perimeter 3 (P3) includes the land area outside the house till the fence but excludes those outside areas in P1. This division of the home into different perimeters permits the employment of different types of HSS in each of the three perimeters making it possible to achieve both high security and high performance at the same time. Typically, P1 will employ a HBS, P2 will utilize a WBS, while P3 can use TBS and passive systems.

In this paper we present the results of applying the perimeter-based security approach for HSS. We developed a prototype HSS in our Home Control Systems Lab and divided the house into the three perimeters. Our research demonstrated that the different types of HSS can be ranked in terms of performance as: HBS > WBS > TBS > PS. However, HBS gave the homeowner the least control while PS gave the homeowner the maximum control over security of the entire home; of course, a high-performance HBS is more expensive than the other types of HSS in many cases. In order to balance both cost and control, we used a WBS for P2 and P3, while for P1 we employed a HBS. The preliminary results are encouraging and indicate that both high security and high performance can be achieved using the perimeter-based approach; however, this achievement comes at the cost of high price-tag for the development and maintenance of the system, and an increase in the overall complexity of the system.

2. Home Security Systems There are at least four different types of HSS based on the technique used to generate alarm as well as the technique used to confirm the alarm: Passive System (PS), Phone-Based System (PBS), the Web-Based System (WBS), and the Hardware-Based System (HBS). The three configurations of HSS are shown in Figure 1.The passive HSS system is the most common system found in most homes today (for example, just one company [2] claims to have several million customers using such a system): the homeowner sets the alarm on as she leaves the house so that if anybody tries to break open a window or a door of the house the alarm alerts an independent monitoring agency using the public phone system (PSTN or Public Switched Telephone Network). Figure 1c illustrates a PS that has a door sensor connected to the home alarm system and when this alarm is triggered by someone opening the door associated with this sensor, the home alarm system will call the independent monitoring agency. However, once the alarm is triggered the confirmation of the alarm to find out if someone indeed opened the door requires a physical visit to the home – this could be done by the homeowner, the independent agent, a neighbor, or law enforcement officer. Figure 1b illustrates the PBS wherein the alarm is generated similarly to the passive system but the confirmation of the alarm could be done over the phone network itself: thus if the door sensor alarm is triggered, the alarm could be received by the homeowner or the independent agent over the phone but the confirmation is also possible using the phone network. Thus for the door sensor, they could confirm by turning on a light outside the door through a switch controlled by a telephone controller that uses the X10 protocol [6] to turn the switch on and have a light detector inside of the door trigger the alarm again – this way the homeowner or the independent agency could confirm that the original door alarm was indeed true.

Figure 1a illustrates the third type of HSS – the web-based system. Here the web server and the home controller are important components of the HSS – the web server serves the web pages from which the home controller may be controlled. Different types of sensors such as the door sensor, motion sensors, and sound sensors are connected to the home controller wirelessly and in case any of them are triggered then the web site generates an alarm page which can be viewed by the homeowner on a web browser on any device including laptops (that may connect to the internet either via wired LAN or wireless LAN), PDA’s (that connect to the internet via wireless LAN), and internet-enabled cell phones (that use the internet service provided by the cell phone company); the confirmation of the alarm is possible by using a control device such as, for example, a camera that can be controlled via the web page to observe the cause of the alarm. Thus the homeowner has much better control over the security of her home using the web-based HSS. Figure 1d illustrates the fourth type of HSS – the hardwarebased system (HBS). In an HBS when sensors are triggered no information is sent to any outside agency including the homeowner; the controller takes the decision and triggers actuators to take immediate action. For example, in most homes when there is an obstruction to the closing of the garage door, the garage door stops closing [7]. This is the fastest method of ensuring security – however, this gives the homeowner the least control, besides being expensive as well. We call such systems HBS, even though the controller may have some software to take decisions, because the hardware is controlled by a tight feedback loop. Our research demonstrated that the different types of HSS can be ranked in terms of performance as: HBS > WBS > TBS > PS (can be seen from Table 2). However, HBS gave the homeowner the least control while PS gave the homeowner the maximum control over security of the entire home; of course, a high-performance HBS is more expensive than the other types of HSS in many cases. The relative rating of the four types of HSS among the non-functional requirements of performance, security, controllability, and cost, is given in Table 1.

3. Perimeter Security for the Home Figure 2 illustrates the concept of perimeter-based approach for HSS. The home area is divided into three different perimeters: perimeter 1 (P1) encircles those areas in the home that need maximum security including swimming pools, bedrooms, home offices, and “valuables” room; perimeter 2 (P2) includes the remaining areas inside the house; perimeter 3 (P3) includes the land area outside the house till the fence but excludes those outside areas in P1. Therefore, the importance of the perimeters follows the relation: P1 > P2 > P3 (perimeter relative importance)

Home

Laptop

Door Sensors

Wired LAN

PDA Web Server

Home Controller

Internet

Wireless LAN

Cameras

Cell Phone Service Provider

Cell Phone

Motion Sensors (a)

Home Door Sensors

Home Alarm

Light Detector Public Switched Telephone Network

Telephone

Light Switch Telephone Controller (b)

Home Door Sensors

Public Switched Telephone Network

Telephone

Home Alarm

(c)

Home

Sensors

Controller Actuators (d)

Figure 1. Four Types of HSS: (a) Web-Based System, (b) Phone-Based System, (c) Passive System, (d) Hardware-Based System

Door P2

P1 Valuables

Yard P3 P1 Fence

Home Office

Window

P1 P1 P2

Bedroom

Garden (P3)

Figure 2. Perimeter-Based Security for the Home

Table 1. Relative Rating of Different HSS Types

HBS WBS PBS PS

Performance High Medium Low Very Low

Security High Medium Low Low

In order to simultaneously improve both performance and security of HSS, while at the same time balancing controllability and cost, different types of HSS are attached to the different perimeters. Typically, HBS is attached to P1, WBS is attached to P2, and PBS and/or PS is attached to P3 so that there is a neat balance between controllability and cost while both performance and security remain high. We could choose to use HBS for P1, P2, and P3, so that both performance and security are high, but then controllability of the entire HSS system will be low while the cost will be prohibitively high; conversely, we could choose to use PS for P1, P2, and P3, but the controllability will now very low, the cost will be low, but both performance and security will be compromised. Next section discusses the performance of perimeter-based security approach.

4. Performance Analysis of Perimeter-Based Security In order to analyze the performance of perimeter-based security, we first analyzed the performance of the different types of HSS. For this purpose we performed experiments in our Home Control Systems Lab using sensors, controllers, and web servers. The experimental set up for the WBS is shown in Figure 3. For HBS we used a garage door controller coupled with motion sensor. For performance analysis we triggered the door sensors and measured several factors including the time taken to inform the affected party (homeowner/ independent agency) of the alarm, the time taken to confirm the alarm, ability to receive the alarms on the different digital devices, the ability to control the different digital devices, and other factors. The results of the analysis are presented in Table 2. From Table 2 it can be seen that the performance decreases as HBS > WBS > PBS > PS. The extent of satisfaction of non-functional requirements for a typical HSS that uses HBS for P1, WBS for P2 and PBS for P3 is given in Table 3 for different percentages of P1, P2, and P3. The performance data for Table 3 is taken from Table2 using the combination of the time taken to inform the alarm and the time taken to confirm the alarm: this is about 1 hour for PS, 105 seconds for PBS, 35 seconds for WBS and about 1 second for HBS. As can be seen from Table 3, the different non-functional requirements are satisfied best when P1, P2, and P3, are equally distributed.

Controllability Low High Low Very Low

Cost High High Medium Low

Web Server

Network Hub Door Lock Sensor

Home Controller

Motion Sensor

Figure 3. Picture of the Web-Based System Setup

However, whenever HBS dominates performance and security go up at the cost of cost and controllability; whenever PBS dominates performance and security tend to go down – however, cost and controllability go down as well.

5. Conclusions and Future Work Digital home are expected to be the norm for future home [1] wherein all aspects of the home can be controlled by digital technology remotely by the homeowner using a device such as the PDA, laptop, or even a cell phone. One of the features of the digital home is the home security systems (HSS) that provide security to the home. Our research has enabled us classify HSS into four types of systems: passive systems (PS), phone-based systems (PBS), web-based systems (WBS), and hardware-based systems (HBS), where each type of system uses a different technique for monitoring and controlling the home security. Among the chief characteristics of HSS are performance, security, controllability, and cost – these non-functional requirements cannot all be realized at the same time and there are always tradeoff involved in their achievement. In order to achieve the high-priority nonfunctional requirements of performance and security at the same time this paper proposes the perimeter-based security approach wherein the home is divided into different perimeters and each perimeter uses a different type of HSS thereby enabling the achievement of high performance and high security at the same time. The perimeter-based security approach is validated by measuring experimental setups in the lab.

Table 2. Performance Analysis Results for the Four Types of HSS Row No.

Parameter Measured

Passive System (PS)

Phone-Based System (PBS)

Web-Based System (WBS)

HardwareBased System (HBS)

1

Technique used to alert the homeowner Time taken to alert the homeowner to the event Technique used to confirm the alarm

Phone call

Phone call

40 seconds

40 seconds

Alarm event on the web site 25 seconds

Home-owner not alerted Home-owner not alerted Hardware-based (controller senses the alarm)

4

Time taken to confirm the event

~ 1 hour

At least 65 seconds

5

Security

Low (long time to confirm the event)

Low (long time to confirm the event)

6

Ability to Control

Low (can only set for alarm conditions locally)

7

Flexibility – monitor and control using different devices

Low (telephone is the only device available for monitor)

Medium (appliances at home including lights can be turned on and off by phone controller) Low (fixed device – only telephone can be used)

8

Remote Accessibility of the System for both Monitor and Control Ease of Use of the System Cost of the System

Low

Medium

High

Very Low – controller needed for each sensor/actuator type Very Low

Low

Medium

High

High

Low ($600 fixed cost; $60 per month recurring costs)

Medium ($1000 fixed cost; $60 per month recurring cost)

High ($2000 fixed cost; $120 per month recurring cost)

Medium ($1000 fixed cost; but due to low flexibility this cost needs to be spent for each sensor/actuator combination)

2 3

9 10

Physical visit by homeowner/neighbor/ independent agent/ law enforcement

Camera control to check the cause of the alarm (confirm open door or presence of person/animal/ thing) Immediate if the camera is pointing to the door; if the camera needs to be swiveled then about 10 seconds. Medium (long time for alarm occurrence but may be confirmed quickly) High (much better control over household equipments – cameras and appliances can be controlled) Medium - works only with IE and Windows XP platforms

1 second (no confirmation occurs; however, security is enforced almost immediately) High (security enforced almost immediately) Very Low

Percentage of P1 100

Table 3. Achievement of Non-Functional Requirements for Perimeter-Based Approach Percentage Percentage Overall HSS Overall HSS Security Overall HSS of P2 of P3 Performance Cost 0 0 High High High (1 second) (since security is provided (since HBS is only by HBS) expensive)

67

33

0

High (13 seconds)

67

0

33

Medium (35 seconds)

33

67

0

Medium (23 seconds)

33

0

67

Low (70 seconds)

Low (since security if mostly provided by PBS for P3)

33

33

33

Medium (47 seconds)

Medium (since high security provided by HBS for P1 tends to be negated by PBS for P3)

0

100

0

Medium (35 seconds)

0

67

33

Low (58 seconds)

0

33

67

Low (83 seconds)

0

0

100

Low (105 seconds)

Medium (since security is provided only by WBS) Low (because of the impact of PBS on security for P3) Low (since security is mostly provided by PBS for P3) Low (since security is only provided by PBS)

For the future we plan to investigate different combinations of HSS types and perimeters for their effect on performance and security. We also plan to extend this study to other systems that may be found in a digital home such as entertainment systems and digital network systems. However,

High (since security is provided mostly by HBS and partly by WBS) Medium (because of the impact of PBS on security for P3) Medium (since security is mostly provided by WBS for P2)

High (since HBS and WBS are expensive) Medium (due to the impact of PBS for P3) High (since HBS and WBS are expensive) Medium (since PBS is relatively inexpensive compared to HBS) Medium (due to the impact of the inexpensive PBS on the overall cost)

Overall HSS Controllability Very Low (since HBS cannot be controlled by homeowner) Low (due to HBS)

Low (due to HBS) Medium (since WBS allows good control) Low (due to low controllability of both HBS and PBS)

High (due to WBS)

Medium (since the negative effect on controllability of HBS and PBS are cancelled by WBS) High (due to WBS)

High (due to WBS)

High (due to WBS)

Low (due to PBS for P3) Low (due to PBS)

Low (due to PBS for P3) Low (due to PBS)

we believe that perimeter-based security is a promising approach to improve performance and security at the same time while not compromising on cost and controllability.

References [1]. “This New House”, Fortune Magazine Special Issue Supplement on How the World Will Work The Next 75 Years, September 19, 2005. [2]. www.adt.com [3]. www.smarthome.com [4]. D. Crane, “Mobile Ballistic Fighting Position for Perimeter Security and Force Protection”, available at www.defensereview.com, June 14, 2007. [5]. G. Kunene, “Perimeter Security Ain’t What It Used to Be, Experts Say”, available at www. Devx.com/security/article/20472 , March 17, 2004. [6]. www.x10.com [7]. www.overheaddoors.com