In this paper, we investigate a distributed fine grain adaptive FEC (FGA-FEC) scheme for scalable video streaming
to heterogeneous users over a congested multihop network, where we do FGA-FEC decode/recode at selected
intermediate overlay nodes, and do FGA-FEC adaptation at remaining nodes. In order to reduce the overall
computational burden, we propose two methods: (1) a coordination between optimization processes running at
adjacent nodes to reduce the optimization computation, and (2) extension of our overlay multihop FEC (OM-FEC<sup>1,
2</sup>) to reduce the number of FGA-FEC decode/recode nodes. Simulations show that the proposed scheme
can greatly reduce computation, and can provide near best possible video quality to diverse users.
In this paper, we propose a two-stage FEC scheme with an enhanced MAC protocol especially for multimedia data transmission over wireless LANs. The proposed scheme enables the joint optimization of protection strategies across the protocol stack, and packets with errors are delivered to the application layer for correction or drop. In stage 1, 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-one FEC packets to recover from bit errors in the MAC/PHY layer. Header CRC/FEC are used to enhance the MAC/PHY layer and to cooperate with the two stage FEC scheme. Thus, we add FEC only at the application layer, but can correct both application layer packet drops and MAC/PHY layer bit errors. We explore both the efficiency of bandwidth utilization and video performance using the scalable video coder MC-EZBC and ns-2 simulations. Simulation results show that the proposed scheme outperforms conventional IEEE 802.11.