Algorithm with Release Stages for Slotted ALOHA Systems

In this paper, we propose a decentralized backo algorithm with release stages. In the proposed algorithm the contention window (CW) of a successful user is gradually decreased, while it is reset to zero after successful transmission in conventional backo algorithms. The rate of decrement of the CW is controlled by the release delay, which is newly introduced by the use of the release stages. The performance of the proposed algorithm is analyzed by means of the equilibrium point analysis in terms of throughput, average and coecient of variation of transmission delay. Numerical results show that the proposed algorithm can significantly improve the performance by properly choosing the parameters. It is also found that the proposed algorithm can achieve long-term fairness in the sense that it can oer small fluctuation of transmission delay, even for improper selection of the parameters such that the throughput is deteriorated.