Saturation throughput analysis of different backoff algorithms in IEEE802.11

We develop a new analytical model of the existing binary exponential backoff (BEB) algorithm in IEEE 802.11 wireless LAN and two different proposals, exponential increase exponential decrease (EIED) and exponential increase linear decrease (EILD) backoff algorithms. A one-dimensional Markov chain model is constructed for each algorithm and used to compare throughput under overload conditions. Our approach simplifies previous analyses of the BEB algorithm which used a 2-dimensional Markov chain model. The saturation throughput as well as average backoff window and probability of success for all three algorithms are calculated and compared in various types of traffic and network loads. Analytical results are compared to the simulation results. We found that EIED performs always better than BEB, while EILD provides improvement at higher loads. Additionally, we show that the infinite retransmission assumption provides a very tight upper bound on throughput for all schemes.