Link quality control benefits from a combined incremental redundancy and link adaptation in EDGE networks

A performance analysis of link quality control (LQC), comprising incremental redundancy (IR) and link adaptation (LA) in EDGE networks has been provided. Both simulated and real system measurement results demonstrate the superiority of the proposed combined IR+LA strategy over pure IR. LLC and TCP/IP protocol stack simulations show that a pure IR strategy causes upper layer protocol implications as well as frequent TCP retransmissions resulting in considerable throughput degradations especially under bad C/I conditions. In this case, a combined IR+LA strategy reduces the TCP/IP packet delay and avoids upper layer timer expiries by switching to a more robust coding scheme. Hence, under bad radio conditions, with IR+LA the application throughput is preserved at an optimum level.