Improvement of ERED FEC Mechanism for Video Transmission Over WLANs

Abstract

Devices like laptops, PDAs, desktops, smartphones and other types of workstations are progressively shifting towards WLAN technology due to the ample advantages it offers like mobility, increased scalability of network, cost effectiveness, availability of internet even in public places and high network speeds without cumbersome wiring. With the advent of wireless technology, a lot research focus has been shifted towards improving the performance of WLANs for transmission of text, audio and video files. In particular, the sharing and transmission of multimedia files over WLANs is becoming commonplace as more and more communication is occurring via technologies like videoconferencing, television broadcasting, video playback and voice over internet. Video transmission in particular presents a challenge in juggling the quality of service parameters with the timeliness of delivery of the video. WLAN typically suffers from low QoS parameters as compared to wired networks. WLANs are noisier, have more delay, higher packet loss rate and are more prone to interference due to overlapping frequencies and physical obstructions. One of main drawbacks of using WLAN is that it suffers from high packet loss rates. This error rate is decreased by using error detection and correction codes. One of the most common schemes used to correct the error is Forward Error Correction (FEC). Schemes like Constant Error FEC, Adaptive FEC and Random Early Detection FEC are commonly used in WLAN but they all fall victim to burst errors. Burst errors are errors which corrupt or lose packets in a continuous sequence. In this scenario bulk of packets are lost in a sequence making it very difficult or even impossible for the packets to be reconstructed at the receiver’s end even with the help of FEC. Thus to overcome the effect of burst errors in transmission, this proposed technique tries to incorporate the concept of interleaving by randomising the position of source packets and the redundant packets produced by the FEC scheme.