Performance evaluation of the GCR block ACK mechanism in IEEE 802.11aa networks
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With the growing demand for multimedia services, video streams have become major traffic sources in the Internet. However, it is challenging to transmit multimedia streams over IEEE 802.11 Wireless Local Area Networks (WLANs) with high performance and reliability. As a solution to improve system efficiency, a new standard, 802.11aa, is introduced to provide much more reliable and robust transfer of video stream by introducing several new service features. In this thesis, we analyze the performance of the Groupcast with Retries (GCR) Block ACK scheme as one of the most important features in this standard based on Markov chain models. The properties of groupcast service and block acknowledgement will be merged together in our model. Besides, we take into account the memory feature of the wireless channel and extend it into multi-receivers in accordance with the standard. In particular, the proposed model is built on fixed block size, a type of communication technique in which the block size is kept as fixed during transmission. Furthermore, the lost position of a packet in the block is taken into consideration for in-depth analysis. Numerical results show that under the groupcast with constant retry limit and fixed block size transmission mechanism, the network throughput will be reduced with the growing number of receiving terminals. Compared with the throughput result for the variable block size mechanism obtained from our previous study, we found that with the increasing number of stations, the performance of the fixed block size mechanism is much more stable with respect to the number of stations and channel memory property. However, the variable block size transmission scheme exhibits much better throughput performance when the number of stations is small.
Masteroppgave i informasjons- og kommunikasjonsteknologi IKT590 2013 – Universitetet i Agder, Grimstad