Abcr-stc: An Improved Adaptive Backoff
Abstract Abstract — In this letter, we are concerned with adaptive ARQ techniques combined with backoff strategies that exploit the bursty nature of wireless links for improved energy savings. Specifically, we propose an adaptive Go-back-N/Stop-and-Wait (GBN/SAW) protocol with backoff and present a renewal reward analysis of the throughput and energy efficiency performance of the proposed scheme. We show that the GBN protocol with a linear backoff (LBO) strategy results in energy savings of about 2 dB compared to GBN with no backoff (NBO) on highly correlated fading channels when the round-trip delays (RTD) are small, and this energy saving decreases as RTD increases.
With adaptive GBN/SAW protocol with LBO, however, the energy saving is retained high even for large RTDs. In fact, the proposed adaptive GBN/SAW protocol with LBO performs quite close to that of an ideal (though not practical) backoff scheme which assumes a priori knowledge of the channel status in each slot. Index Terms — Adaptive ARQ, backoff, energy efficiency, Goback-N, Stop-and-Wait, round-trip delay.
In this paper, we propose three backoff algorithms for Ad hoc networks. The first algorithm aims at higher fairness, and the second aims at stronger adaptivity. Then, we combine the first two algorithms to propose an optimized backoff algorithm.
Abcr-stc An Improved Adaptive Backoffice
Abstract Carrier sense multiple access mechanism with collision avoidance (CSMA/CA) in IEEE 802.15.4-based wireless body area networks (WBANs) may impair the transmission reliability of emergency traffic under high traffic loads, which may result in loss of high valued medical information. Majority of the recent proposals recommend an early retransmission of failed frame while ignoring the history of past failed transmissions. More importantly, these proposals do not consider the number of failed transmissions experienced by each sensor node, thereby affecting the reliability of retransmissions. In this paper, we propose a dynamic retransmission adaptive intelligent MAC (RAI-MAC) scheme. In our proposed scheme retransmission class of each sensor node is decided by the coordinator according to the number of failed transmissions of each node as observed by the coordinator during the last superframe. Based on the retransmission class received from the coordinator, each node adjusts its next backoff value.
The proposed scheme increases the probability of successful frame retransmissions without incurring extra overhead. The simulation results prove that the proposed scheme based on its adaptive retransmission mechanism achieves higher average throughput and average end-to-end delay, while not compromising on energy efficiency as compared to the IEEE 802.15.4 and Block Acknowledgment (Block Ack). Moreover, our scheme appears more stable in terms of average throughput, end-to-end delay, and energy efficiency under different values of beacon order (BO) and superframe order (SO).