Supplement schemes to 3GGP ARQ for reducing occupancy and sojourn at re-ordering buffer

3GPP RLC protocol specification adopted an error control scheme based on window-controlled selective-repeat ARQ. As a member of selective-repeat clan, the 3GPP ARQ inherently possesses the problem of re-ordering at the receiving station. In this paper, aiming at suppressing the occupancy and sojourn time at the re-ordering buffer while maintaining the level of delay and throughput performance, we propose two schemes (identified as confined selective-repeat and extended go-back-N schemes) as a supplement to the 3GPP ARQ. For the performance evaluation of the proposed schemes, we first develop an approximation method to calculate the maximum throughput of a window-controlled ARQ. Secondly, using a simulation method, we investigate the peak occupancy, mean sojourn time, mean delay time, and maximum throughput exhibited by the schemes in various environments. From numerical examples, we confirm the validity of our approximation method and conclude that the proposed schemes are able to improve the delay and throughput performance of the 3GPP ARQ without inflating the occupancy and sojourn time at the re-ordering buffer.