Applications of “Cross-Layer” in Video Communications over Wireless Networks

Because of the impact of noise, interference, fading, and shadowing in a wireless network, there has been a realization that the strict layering of wireline networks may be unsuitable for wireless. It is the volatility over time that demands an adaptive solution and the basis of adaptation must arise by communication of the channel conditions along with the datalink settings. Video communication is particularly vulnerable because, except when reception is decoupled from distribution as in multimedia messaging, there are real-time display and decode deadlines to be met. The predictive nature of video compression also makes it susceptible to temporal error propagation. In this chapter, case studies from the authors’ experiences with broadband wireless access networks and personal area wireless networks serve to illustrate how information exchange across the layers can benefit received video quality. These schemes are all adaptive and serve as a small sample of a much greater population of cross-layer techniques. Given the importance of multimedia communications as an engine of growth for networked communication, “cross-layer” should be the first consideration in designing a video application.