A survey on wireless multimedia sensor networks.docx

1、A survey on wireless multimedia sensor networksA survey on wireless multimedia sensor networksIan F. Akyildiz *, Tommaso Melodia, Kaushik R. ChowdhuryBroadband and Wireless Networking Laboratory, School of Electrical and Computer Engineering, Georgia Institute of Technology,Atlanta, GA 30332, United

2、 StatesReceived 11 March 2006; received in revised form 6 August 2006; accepted 5 October 2006Available online 2 November 2006AbstractThe availability of low-cost hardware such as CMOS cameras and microphones has fostered the development of Wire-less Multimedia Sensor Networks (WMSNs), i.e., network

3、s of wirelessly interconnected devices that are able to ubiqui-tously retrieve multimedia content such as video and audio streams, still images, and scalar sensor data from theenvironment. In this paper, the state of the art in algorithms, protocols, and hardware for wireless multimedia sensor net-w

4、orks is surveyed, and open research issues are discussed in detail. Architectures for WMSNs are explored, along withtheir advantages and drawbacks. Currently o-the-shelf hardware as well as available research prototypes for WMSNsare listed and classied. Existing solutions and open research issues at

5、 the application, transport, network, link, and phys-ical layers of the communication protocol stack are investigated, along with possible cross-layer synergies andoptimizations._ 2006 Elsevier B.V. All rights reserved.Keywords: Wireless sensor networks; Multimedia communications; Distributed smart

6、cameras; Video sensor networks; Energy-awareprotocol design; Cross-layer protocol design; Quality of service1. IntroductionWireless sensor networks (WSN) 22 have drawnthe attention of the research community in the lastfew years, driven by a wealth of theoretical andpractical challenges. This growing

7、 interest can belargely attributed to new applications enabled bylarge-scale networks of small devices capable of har-vesting information from the physical environment,performing simple processing on the extracted dataand transmitting it to remote locations. Signicantresults in this area over the la

8、st few years have ush-ered in a surge of civil and military applications. Asof today, most deployed wireless sensor networksmeasure scalar physical phenomena like tempera-ture, pressure, humidity, or location of objects. Ingeneral, most of the applications have low band-width demands, and are usuall

9、y delay tolerant.More recently, the availability of inexpensivehardware such as CMOS cameras and microphonesthat are able to ubiquitously capture multimediacontent from the environment has fostered the1389-1286/$ - see front matter _ 2006 Elsevier B.V. All rights reserved.doi:10.1016/net.2006.10.002

10、*Corresponding author. Tel.: +1 404 894 5141; fax: +1 404 8947883.E-mail addresses: ianece.gatech.edu (I.F. Akyildiz), tomma-soece.gatech.edu (T. Melodia), kaushikcece.gatech.edu(K.R. Chowdhury).Computer Networks 51 (2007) 921960 of Wireless Multimedia Sensor Net-works (WMSNs) 54,90, i.e., networks

11、of wirelesslyinterconnected devices that allow retrieving videoand audio streams, still images, and scalar sensordata. With rapid improvements and miniaturizationin hardware, a single sensor device can be equippedwith audio and visual information collection mod-ules. As an example, the Cyclops image

12、 capturingand inference module 103, is designed for extre-mely light-weight imaging and can be interfacedwith a host mote such as Crossbows MICA2 4or MICAz 5. In addition to the ability to retrievemultimedia data, WMSNs will also be able to store,process in real-time, correlate and fuse multimediada

13、ta originated from heterogeneous sources.Wireless multimedia sensor networks will notonly enhance existing sensor network applicationssuch as tracking, home automation, and environ-mental monitoring, but they will also enable severalnew applications such as: Multimedia surveillance sensor networks.

14、Wirelessvideo sensor networks will be composed of inter-connected, battery-powered miniature videocameras, each packaged with a low-power wire-less transceiver that is capable of processing,sending, and receiving data. Video and audiosensors will be used to enhance and complementexisting surveillanc

15、e systems against crime andterrorist attacks. Large-scale networks of videosensors can extend the ability of law enforcementagencies to monitor areas, public events, privateproperties and borders. Storage of potentially relevant activities.Multime-dia sensors could infer and record potentially rel-e

16、vant activities (thefts, car accidents, tracviolations), and make video/audio streams orreports available for future query. Trac avoidance, enforcement and control sys-tems. It will be possible to monitor car trac inbig cities or highways and deploy services thatoer trac routing advice to avoid cong

17、estion.In addition, smart parking advice systems basedon WMSNs 29 will allow monitoring availableparking spaces and provide drivers with auto-mated parking advice, thus improving mobilityin urban areas. Moreover, multimedia sensorsmay monitor the ow of vehicular trac onhighways and retrieve aggregat

18、e informationsuch as average speed and number of cars. Sen-sors could also detect violations and transmitvideo streams to law enforcement agenciesto identify the violator, or buer images andstreams in case of accidents for subsequent acci-dent scene analysis. Advanced health care delivery. Telemedic

19、ine sen-sor networks 59 can be integrated with 3G mul-timedia networks to provide ubiquitous healthcare services. Patients will carry medical sensorsto monitor parameters such as body temperature,blood pressure, pulse oximetry, ECG, breathingactivity. Furthermore, remote medical centerswill perform

20、advanced remote monitoring oftheir patients via video and audio sensors, loca-tion sensors, motion or activity sensors, whichcan also be embedded in wrist devices 59. Automated assistance for the elderly and familymonitors. Multimedia sensor networks can beused to monitor and study the behavior of e

21、lderlypeople as a means to identify the causes ofillnesses that aect them such as dementia 106.Networks of wearable or video and audio sensorscan infer emergency situations and immediatelyconnect elderly patients with remote assistanceservices or with relatives. Environmental monitoring. Several pro

22、jects onhabitat monitoring that use acoustic and videofeeds are being envisaged, in which informationhas to be conveyed in a time-critical fashion.For example, arrays of video sensors are alreadyused by oceanographers to determine the evolu-tion of sandbars via image processing techniques58. Person

23、locator services. Multimedia content suchas video streams and still images, along withadvanced signal processing techniques, can beused to locate missing persons, or identify crimi-nals or terrorists. Industrial process control. Multimedia contentsuch as imaging, temperature, or pressureamongst othe

24、rs, may be used for time-criticalindustrial process control. Machine vision is theapplication of computer vision techniques toindustry and manufacturing, where informationcan be extracted and analyzed by WMSNs tosupport a manufacturing process such as thoseused in semiconductor chips, automobiles, f

25、oodor pharmaceutical products. For example, inquality control of manufacturing processes,details or nal products are automaticallyinspected to nd defects. In addition, machinevision systems can detect the position and orien-tation of parts of the product to be picked up bya robotic arm. The integrat

26、ion of machine vision922 I.F. Akyildiz et al. / Computer Networks 51 (2007) 921960systems with WMSNs can simplify and addexibility to systems for visual inspections andautomated actions that require high-speed,high-magnication, and continuous operation.As observed in 37, WMSNs will stretch thehorizo

27、n of traditional monitoring and surveillancesystems by: Enlarging the view. The Field of View (FoV) of asingle xed camera, or the Field of Regard (FoR)of a single moving pan-tilt-zoom (PTZ) camera islimited. Instead, a distributed system of multiplecameras and sensors enables perception of theenviro

28、nment from multiple disparate viewpoints,and helps overcoming occlusion eects. Enhancing the view. The redundancy introducedby multiple, possibly heterogeneous, overlappedsensors can provide enhanced understandingand monitoring of the environment. Overlappedcameras can provide dierent views of the s

29、amearea or target, while the joint operation ofcameras and audio or infrared sensors can helpdisambiguate cluttered situations. Enabling multi-resolution views. Heterogeneousmedia streams with dierent granularity can beacquired from the same point of view to providea multi-resolution description of

30、the scene andmultiple levels of abstraction. For example, staticmedium-resolution camera views can be enrichedby views from a zoom camera that provides ahigh-resolution view of a region of interest. Forexample, such feature could be used to recognizepeople based on their facial characteristics.Many

31、of the above applications require the sen-sor network paradigm to be rethought in view ofthe need for mechanisms to deliver multimedia con-tent with a certain level of quality of service (QoS).Since the need to minimize the energy consumptionhas driven most of the research in sensor networksso far, mechanisms to eciently deliver applicationlevel QoS, and to map these requirements to net-work layer metrics such as latency and jitter, havenot been primary concerns in mainstream researchon classical se