A Scalable Feedback Suppression Mechanism for Multicast Service in Wireless TDMA Network

Hybrid ARQ is deployed in error prone wireless network to provide reliable unicast transmission with the positive or negative acknowledgement report. However, the feedback implosion is a challenging problem for multicast service, wherein multiple receivers send out feedback in a short period of interval. The traditional representative-based or timer-based feedback suppression method can not provide adequate accuracy or latency guarantee; and the approach to monitor packet loss rate from each receiver has poor performance in scalability. This paper investigates the relation between feedback overhead and average recovery rate for multicast service in Time Division Multiple Access (TDMA) based wireless network. A scalable aggregate feedback mechanism is proposed to corporate with either fix-rate or rateless channel coding scheme. Receivers who can not recover the data block are assigned to send identical NACK message at the same uplink feedback time slot, so that the sender can acquire a global view of the data block reception condition, an adaptive sliding window is defined in accordance with the previous NACK statistics, dynamic number of recovery parity symbols are delivered in each window following the sequence of exponent or arithmetical serial. Comparing with the conventional feedback suppression mechanism, the simulation results show the proposed mechanism can not only adjust the traffic of parity packets to match the actual reception condition among all receivers, but also greatly reduce the feedback overhead and improve the scalability.