The Transformation of Video Surveillance Systems
Thu, 05/17/2007 - 11:38am
Wireless IP video surveillance systems have gained momentum because of their flexibility and reduced installation costs.By Haoming (Ming) Huang, Fujitsu Microelectronics America, Inc.
The maturing of fixed WiMAX technology is making possible a number of exciting new applications that previously were limited by cost, distance and throughput requirements. With the latest wireless innovations, fixed wireless applications now go beyond mere short-range data communications, and do so in a secure manner. Superior outdoor performance, proven quality of service (QoS) and solid security enable WiMAX to support valuable multimedia applications, such as network video for surveillance.
The Rising Demand for SurveillanceIncreasing security concerns have forced governments and enterprises to invest significantly in safety features for infrastructure, industry and institutions. One of the most powerful weapons against terrorism is video surveillance.
Created initially as security for banks in the 1940s, video surveillance systems have evolved to become one of the most popular safety and security systems today. It is
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Table 1. WiMAX Service Type
Thanks to rapid advances in modern technologies, video surveillance has had a complete makeover from analog to digital format, making it possible to run surveillance over Internet Protocol (IP) networks. In addition, it offers more advanced options such as wireless networking, higher resolution, color systems, biometrics, smart sensors and intelligent analysis software. These newly added features are useful in a variety of applications such as industrial automation, transportation, automotive, security/surveillance and communications.
Wireless IP Video Surveillance SystemsAmong these options, wireless IP video surveillance systems have gained momentum because of their flexibility. The wireless option has the advantage of being easy to set up and easily concealed, since there are no wires to hide. Installation is more cost effective, and it is possible to monitor virtually any location as long as there is a computer with Internet connectivity close at hand.
Traditional analog wireless surveillance systems cannot flexibly and inexpensively take advantage of the readily available IP network infrastructures. Due to limited range, analog wireless cannot encompass a wide area without a repeater. Digital migration eliminates this drawback because the captured image can be stored in IP packets and carried within IP network reach.
Most wireless IP video surveillance systems are currently IEEE (Institute of Electrical and Electronics Engineers) 802.11-based because of WiFi's cost effectiveness. However, the 802.11 solution is limited to 100 meter coverage, and thus is suitable only for indoor applications such as baby monitoring and small business surveillance. Its contention-based MAC also makes it challenging to deliver the necessary throughput and QoS of a video surveillance system.
WiFi's less reliable security features also create uncertainties for applications like surveillance systems. Some vendors offer solutions using proprietary wireless technologies, but the cost of this equipment is usually high, due to relatively low volume and custom designed components.
The stage is now set for the next generation of wireless IP video surveillance systems. Because of the early success of the IEEE 802.11 standards, the world has had a taste of the portability and flexibility of wireless. The IEEE proposed the 802.16 standard to deliver better performance for wireless metropolitan area networks (MANs).
WiMAX AdvantagesWiMAX has many cost/performance advantages over its WiFi counterpart and other proprietary solutions, including higher throughput and longer distance than many competitive wireless technologies. The maximum raw data throughput of WiMAX is up to 72 Mb/s, almost seven times that of IEEE 802.11b and 50% greater than that of IEEE 802.11a/g. Many carrier wired solutions still deliver no more than 1 Mb/s. The distance reached by a WiMAX network is tens of kilometers, compared to WiFi's maximum of 100 meters.
Based on the proven technology of OFDM (Orthogonal Frequency Division Multiplexing), WiMAX is better able to address significant challenges within a NLOS (Non-Line of Sight) environment than WiFi. NLOS, the major reason for a multi-path environment, can cause signal delays, and signals in outdoor environments generally have longer reach than those in indoor environments. So to support NLOS operation, WiMAX uses more subcarriers. While WiFi uses 64 subcarriers, WiMAX uses 256 subcarriers. The ratio of cyclic prefix, i.e., the subcarriers which battle NLOS but carry non-useful data, to the total number of subcarriers in WiMAX is much smaller than with WiFi. Thus WiMAX has higher efficiency and better NLOS performance.
In addition, WiMAX's scheduling algorithm provides the necessary QoS for time-sensitive voice and video traffic. Four service types Unsolicited Grant Service (UGS), Real-Time Polling Service (rtPS), Non-Real-Time Polling Service (nrtPS) and Best Effort (BE) categorize traffic. Table 1 shows WiMAX's class of service types. In contrast, 802.11 uses CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance), a contention access mechanism. WiFi subscriber stations closer in range have a higher chance of access than more distant stations, thus hampering any meaningful QoS for applications like video.
WiMAX has built-in data encryption to prevent eavesdropping. Unlike other wireless technologies, WiMAX mandates the Data Encryption Standard (DES) for data, and triple DES for key encryption. The Advanced Encryption System (AES) is an optional WiMAX feature for more security-sensitive applications.
Highly integrated WiMAX semiconductors like SoC (System on Chip) and RFIC (Radio Frequency Integrated Circuit) significantly reduce on-board components and board size, cutting down the total manufacturing Bill of Material (BOM) cost. The open standard helps reduce the cost of manufacturing WiMAX products and speeds up market adoption, resulting in higher volume demands.
Above and beyond the basics of the 802.16-2004 standard, numerous WiMAX silicon innovations have also been delivered to further boost performance advantages, including: Support for both subscriber stations and base stations for TDD or FDD applications
High-performance modulation capabilities, for complete versatility
256 OFDM PHY with 64QAM, 16QAM, QPSK, and BPSK modulation
Uplink subchannelization for up to 16 sub-channels
High-performance ADC and DAC for flexible baseband interfacing
Automatic frequency control (AFC) with integrated DAC
Dynamic frequency selection (DFS) with integrated ADC
Integrated ADC for transmit and receive power measurements
Integrated peripherals and Radio Frequency (RF) control
Programmable automatic gain control (AGC) to support a broad range of RF attenuators
Security implementation based on DES and AES/CCM encryption/decryption
Dual RISC processors for implementing upper- and lower-layer MAC
Integrated memory controller and DMA controller
Integrated Ethernet engine for network interface
Highly compact package
Complete reference design with software and radio solution.
WiMAX-based Wireless IP Video Reference DesignThe wireless camera design can be divided into two logical modules, the video camera and the WiMAX wireless modem. The most rational interface between the two modules is an Ethernet interface, since most video processors on the market, such as Texas Instruments' TMS320DM64x family DSP, are equipped with an Ethernet MAC (Media Access Controller) interface. Low bandwidth applications can also take advantage of the built-in SPI (Serial Peripheral Interface) in the WiMAX SoC, using it as a communications interface.
In the video camera module, a video camera head captures images and provides the input to an image sensor array, usually via an amplifier. The array passes the data to Analog to Digital Converters
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Figure 1. WiMAX-based Wireless IP Video Surveillance Camera Reference Design.
The IP video images are then transmitted to the WiMAX wireless modem module through the Ethernet interface. The SoC packs the Ethernet packets into WiMAX frames before transmitting them over the air through an RF module. The RF module converts the WiMAX digital signal into analog signals in a preferred operating frequency band and passes the RF signals to an antenna. The WiMAX wireless modem can also receive signals in the opposite direction, allowing control signals like panning, tilting and zooming, to manage the attached video camera.
The WiMAX SoC has an interface allowing designers to use an external processor to bypass the internal ARM processor. The design offers the flexibility to utilize a more powerful processor than the ARM, if a higher data rate is needed for high-resolution applications. Moreover, such designs allow designers to have more communications interface options. The tradeoff is the cost of an additional external processor.
SummaryWiMAX innovation facilitates exceptional performance and affordability for next-generation wireless IP video surveillance systems. Emerging and maturing wireless technologies enable cost-effective commercial surveillance systems to be adopted in many new areas, where traditionally such systems were impossible or impractical. More information on the IEEE 802.16 standard for broadband wireless access and the WiMAX Forum is available at www.wimaxforum.org and www.ieee802.org/16.
About the Author
Haoming (Ming) Huang is a product manager at Fujitsu Microelectronics America, Inc., responsible for the marketing and sales of the company's WiMAX product lines.