Analysis and performance assessment of a fragment retransmission scheme for energy efficient IEEE 802.11 WLANs.

Prosper Mafole,Masayoshi Aritsugi

doi:10.1186/s40064-016-3023-6

Prosper Mafole, Masayoshi Aritsugi

Open Access

https://doi.org/10.1186/s40064-016-3023-6

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Abstract

Backoff-free fragment retransmission (BFFR) scheme enhances the performance of legacy MAC layer fragmentation by eliminating contention overhead. The eliminated overhead is the result of backoff executed before a retransmission attempt is made when fragment transmission failure occurs within a fragment burst. This paper provides a mathematical analysis of BFFR energy efficiency and further assesses, by means of simulations, the energy efficiency, throughput and delay obtained when BFFR is used. The validity of the new scheme is evaluated in different scenarios namely, constant bit rate traffic, realistic bursty internet traffic, node mobility, rigid and elastic flows and their combinations at different traffic loads. We also evaluate and discuss the impact of BFFR on MAC fairness when the number of nodes is varied from 4 to 10. It is shown that BFFR has advantages over legacy MAC fragmentation scheme in all the scenarios.

Highlights

Energy efficiency has impact on the global energy consumption and, as a result of energy generation process, the emission of carbon dioxide
We have provided a mathematical basis which shows that Backoff-free fragment retransmission (BFFR) is superior to classical fragmentation (CF)
The paper has assessed the performance of BFFR in different scenarios namely, traffic types, STAs mobility and transport protocols

Summary

Background

Energy efficiency has impact on the global energy consumption and, as a result of energy generation process, the emission of carbon dioxide. To reduce energy consumption of STAs operating in CAM the authors in Mafole et al (2014a, b) selected the concept of eliminating contentions, IFSs and ACK They proposed a fragment retransmission scheme that enhances the energy efficiency of WLANs by reducing contention overhead which STAs incur as a result of executing the backoff procedure whenever channel induced errors occur within a fragment burst. This is made possible by Eq 2 which requires other STAs to wait for the medium to be idle for a TDIFS, before they attempt to make a transmission, while the retransmission occurs a TSIFS after an STA has received the notification This scheme is called backoff-free fragment retransmission (BFFR) fragmentation whose operation is shown in Algorithm 2.

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