Backoff algorithms are typically employed in multiple-access networks (e.g., Ethernet) to recover from packet collisions. We propose and carry out the analysis for three types of link-layer backoff schemes, namely linear backoff, exponential backoff, and geometric backoff, on point-to-point wireless fading links where packet errors occur non-independently. In such a scenario, the backoff schemes are shown to achieve better energy efficiency without compromising much on the link layer throughput performance.

In this paper, we analyze the throughput and energy efficiency performance of user datagram protocol (UDP) using linear, binary exponential, and geometric backoff algorithms at the link layer (LL) on point-to-point wireless fading links. Using a first-order Markov chain representation of the packet success/failure process on fading channels, we derive analytical expressions for throughput and energy efficiency of UDP/LL with and without LL backoff. The analytical results are verified through simulations. We also evaluate the mean delay and delay variation of voice packets and energy efficiency performance over a wireless link that uses UDP for transport of voice packets and the proposed backoff algorithms at the LL. We show that the proposed LL backoff algorithms achieve energy efficiency improvement of the order of 2-3 dB compared to LL with no backoff, without compromising much on the throughput and delay performance at the UDP layer. Such energy savings through protocol means will improve the battery life in wireless mobile terminals.

We analyze the throughput, delay and energy efficiency performance of space diversity slotted ALOHA when multibeam smart antenna arrays capable of steering the beams selectively on smaller sectors, are used at the base station receiver. Analytical expressions to establish the effect of different beamwidths, number of beams, beam steering patterns, and beam service times on the achieved performance of S-ALOHA an derived. We show that under high load conditions steered beams with long beam service times offer better performance, whereas under light loads static coverage patterns an better. We propose and analyze an energy efficient version of S-ALOUA which uses a beam sensed backoff algorithm at the user terminal. We show that the beam sensed backoff algorithm results in significant energy saving that could potentially increase battery life in wireless user terminals.

Backoff algorithms are traditionally employed in multiple access networks, like Ethernet, to recover from packet collisions. We propose and carry out the analysis for three types of link layer backoff schemes-linear, binary exponential, geometric-on point-to-point wireless fading links, where packet errors occur non-independently. In such a scenario, the back-off schemes are shown to achieve better energy efficiency without compromising much on the link layer throughput performance.