A Novel Random Backoff Algorithm to Enhance the Performance of IEEE 802.11 DCF

Abstract

The Probability Distribution of Slot Selection (PDoSS) of IEEE 802.11 DCF is extremely uneven, which makes the packet collision probability very high. In this paper, we propose a novel RWBO+BEB backoff algorithm for 802.11 DCF to make the PDoSS even and thus decrease the packet collision probability. A Markov model is built for analyzing RWBO+BEB's PDoSS and saturation throughput. The model's correctness is validated by simulation. The performance of RWBO+BEB is also evaluated by simulation in terms of PDoSS, saturation throughput, packet collision probability and packet delay. The simulation results indicate that RWBO+BEB can decrease the packet collision probability to a large extent, utilize the channel more efficiently, and make the packet delay jitter much lower comparing to 802.11 DCF. Moreover, we analyze the relation of saturation throughput and packet collision probability to walking probability ( p d ) and contention windows (w), respectively. The analysis indicates that RWBO+BEB has a remarkable feature: its saturation throughput keeps high, and packet collision probability keeps very low (which under 0.1) in a large range of p d and w, this allows us to configure p d and w more flexibly.

Performance enhancement of IEEE 802.11 DCF using novel backoff algorithm

“…The first type statically adjusts the contention window size when continuous packet collision is detected [1,5,6]. The other type dynamically adjusts the contention window size on the basis of the type of network environment [4,[7][8][9].…”

“…Yun et al [5] proposed a random walking backoff (RWBO) algorithm to enhance the performance of the IEEE 802.11 DCF. In the RWBO algorithm, the BEB algorithm decreases the backoff value by 1 with probability p d (0 < p d < 1).…”

“…The mean cw for each distribution (Table 2) is computed in accordance with the RWBO + BEB(0.25) [5]. Figure 5 shows that the normalized throughput and conditional collision probability with different nodes of the binominal backoff algorithm are apparently better than other distributions.…”

“…In [4], it was proved that the analyzed result was slightly better than the simulation result (uniform distribution). In addition, Li et al [5] have pointed out that very little research has been done on the probability distribution of slot selection. Even though some improvements have been proposed by Li et al [5], however, they did not consider how to improve the performance of throughput and collision probability under the same cw mean value.…”

Dynamic tuning of the IEEE 802.11 distributed coordination function to derive a theoretical throughput limit

“…Currently, the methods of improving Backoff performance can be divided into two categories: (1) adjusting the CW size according to the number of times that collisions have occurred [1][2][3], and (2) dynamically adjusting the CW size by detecting changes in the network environment [4][5][6][7]. In the first type of method, the adjustment of CW size only occurs after a collision; the consequences are that the cost for collision must first be paid before the method can find the most appropriate CW size, and that this entire process is repeated when the data are transferred successfully.…”