Efficient transmission of ARQ feedback for EGPRS radio link control

ARQ feedback in enhanced general packet radio service (EGPRS) is provided through the use of bitmaps that indicate the receipt status of individual radio link control (RLC) blocks. The use of a robust coding and modulation scheme for the transmission of ARQ feedback limits the length of the bitmap that can be accommodated in a single feedback message to a fraction of the receiver window. Depending on the feedback frequency, round trip delay and the rate of transmission of RLC blocks, incomplete feedback may cause considerable protocol stalling. In this paper, the loss of throughput due to partial feedback is characterized. We also propose various techniques that minimize protocol stalling through the efficient transmission of multiple non-overlapping bitmaps that cover the receiver window. Simulation results show the relative benefits of the proposed techniques