Authors: K. Sakthi Mala; P. Navaneethan
Addresses: Department of CT&A, Coimbatore Institute of Technology, Coimbatore 641 014, India ' Electrical and Electronics Engineering Department, PSG College of Technology, Coimbatore 641 004, India
Abstract: IEEE 802.16 supports Automatic Repeat request (ARQ) at the link layer to provide reliable service. ARQ retries sending a data-unit until the transmission is successful or maximum retries has reached. For applications which require reliability, the dropped data-unit is to be recovered at the transport layer level by TCP, which operates over ARQ. While TCP's retransmission policy continuously adjusts retransmission-timeout (RTO) based on the current round-trip-time, ARQ uses the static parameters set during the connection set-up procedure. This paper uses simulations to study the impact of one such static ARQ parameter, ARQ_BLOCK_LIFETIME on the performance of TCP-NewReno over IEEE 802.16 for Best Effort (BE) up-link traffic. Simulations were carried out using modified version of NS-2 WiMAX Simulator Release 2.6. The performance metric considered is TCP goodput. The results from the simulations show that the optimal value for ARQ_BLOCK_LIFETIME is influenced by Round Trip Time (RTT), the network-load, and error-rate.
Keywords: transmission control protocol; TCP-NewReno; ARQ; ARQ_BLOCK_LIFETIME; WiMAX; IEEE 802.16; wireless networks; automatic repeat request; simulation; round trip time; RTT; network load; error rate; performance evaluation.
International Journal of Wireless and Mobile Computing, 2013 Vol.6 No.2, pp.143 - 151
Received: 21 Jan 2012
Accepted: 22 Mar 2012
Published online: 15 May 2013 *