IMPROVING WLAN PERFORMANCE WITH ENHANCED MAC, NODE COOPERATION AND TWO-STAGE FEC SCHEME

Signal interference, route disruption, congestion and fluctuations cause several consecutive bits arriving at the receiver in error. The error handling method in tradition communication protocols is error detection and retransmission. This method is inappropriate for distributed multimedia systems for two reasons: It introduces variable delay unacceptable for isochronous streams, and it is very inefficient and difficult to use in the multicast environment typical for many multimedia applications. We propose Enhanced MAC Node Cooperation with Two-Stage Forward Error Correction Scheme to be used on WLANs. The proposed scheme enables the joint optimization of protection strategies across the protocol stack. Node cooperation technique improves networks’ overall system throughput and reliability, reduces the cost of retransmission and energy consumption. In stage 1 of FEC, packet-level FEC is added across packets at the application layer to correct packet losses due to congestion and route disruption. In stage 2, bit-level FEC is processed within both application packets and stage 1 FEC packets to recover from bit errors in the MAC/PHY layer. Thus, we add FEC at the application layer to correct both application layer packet errors and MAC/PHY layer bit errors. MAC is enhanced to support node cooperation and header CRC.

[1]  Levente Buttyán,et al.  Cooperative packet forwarding in multi-domain sensor networks , 2005, Third IEEE International Conference on Pervasive Computing and Communications Workshops.

[2]  Vikram Srinivasan,et al.  Cooperation in wireless ad hoc networks , 2003, IEEE INFOCOM 2003. Twenty-second Annual Joint Conference of the IEEE Computer and Communications Societies (IEEE Cat. No.03CH37428).

[3]  Su Yi,et al.  Error control code combining techniques in cluster-based cooperative wireless networks , 2005, IEEE International Conference on Communications, 2005. ICC 2005. 2005.

[4]  Avideh Zakhor,et al.  Path diversity with forward error correction (PDF) system for packet switched networks , 2003, IEEE INFOCOM 2003. Twenty-second Annual Joint Conference of the IEEE Computer and Communications Societies (IEEE Cat. No.03CH37428).

[5]  John W. Woods,et al.  Two-stage FEC scheme for scalable video transmission over wireless networks , 2005, SPIE Optics East.

[6]  Node cooperation in hybrid ad hoc networks , 2006, IEEE Transactions on Mobile Computing.

[7]  I Chih-Lin,et al.  Wireless Communications and Networks , 2004 .

[8]  Wolfgang Effelsberg,et al.  Adaptable Forward Error Correction for Multimedia Data Streams , 1993 .