On error correction based on feedback jamming in OFDM-based wireless MBMS systems

Erasure error correction by retransmission based on feedback jamming is a mechanism that has been proposed for wireless networks to reduce the overhead of collecting feedback about reception of the same data from multiple receivers (multicast). This is achieved by aggregating feedback from all receivers within the same time slot. Cancellation of a single positive feedback message by negative feedback within the same time slot triggers a retransmission. Yet, this feedback jamming may not be perfectly reliable. In this paper, we evaluate the residual error of a low-delay feedback aggregation and jamming multicast retransmission protocol in the presence of i.i.d. erasures and medium access collisions in large OFDM based MBMS systems by example of 802.11 wireless LANs. We show by simulation how the residual error due to an imperfect jamming can be tuned to meet a certain residual error rate, as e.g. required by audio-visual codecs, and that it becomes negligible for large groups of receivers.