Delay analysis and dynamic tuning of an acknowledged mode radio link control protocol

In this paper, in-sequence delivery delay of an acknowledged mode radio link control (AM-RLC) protocol in wideband code division multiple access (W-CDMA) networks is studied. Two special protocol phenomena, duplicated retransmission, and delayed acknowledgment, are reported. A two-step dependent Markov chain is adopted to model the AM-RLC protocol. The in-sequence delivery is evaluated by means of an analysis through tracking the transmission status of a specific packet data unit (PDU) and its blocking PDUs. Analysis results indicate that in-sequence delivery delay is approximately linear with frame error rate. Analysis results also exhibit that in-sequence delivery delay is highly related to status report interval. Based on this observation, a dynamic AM-RLC scheme is proposed. The proposed AM-RLC scheme dynamically changes status report interval according to channel status. Extensive simulations are carried out to verify the effectiveness of the proposed scheme. It is found that the proposed scheme can reduce status report without penalty to in-sequence delivery delay.