KEYWORDS: Standards development, Video, Local area networks, Fluorescence correlation spectroscopy, High dynamic range imaging, Receivers, Networks, Orthogonal frequency division multiplexing, Roads
The next Generation IEEE 802.11n is designed to improve the throughput of the existing standard 802.11. It aims to
achieve this by increasing the data rate from 54 Mbps to 600 Mbps with the help of physical layer enhancements.
Therefore, the Medium Access Layer (MAC) requires improvements to fully utilize the capabilities of the enhanced
802.11n physical layer. In this paper, we present the performance evaluation results of two frame aggregation schemes
viz., MAC Protocol Data Unit Aggregation (A-MPDU) and MAC Service Data Unit Aggregation (A-MSDU) and study
their performance impact when the two schemes are incorporated in a p-persistent based 802.11n. The simulation results
have shown that the two schemes achieve consistent performance improvement over the standard non-aggregation
scheme.
In this paper, we evaluate the packet latency performance of a new scheduler-based scheme that we have implemented
on top of the p-persistent 802.11 MAC layer. We extended Cali's dynamic p-persistent 802.11 protocol from single class
to multiple classes by means of a weighted fair queuing scheduler built on top of the MAC p-persistent layer. We used
the NS2 simulator in the implementation and testing of our multiple-class scheduler and incorporated the scheduler-based
architecture by modifying the NS2's 802.11 DCF implementation and the protocol stack of the wireless node. Our
tests showed that AEDCF cannot maintain the same throughput differentiation ratios among different traffic classes
under different loads. In contrast, the p-persistent Scheduler scheme maintains the desired differentiation ratios under
different loads, gives higher total network throughput and provides easier tuning. We present detailed performance
results of the scheduler-based architecture in terms of QoS differentiation and packet latency. All tests were
implemented in NS2. The paper concentrates on single hop wireless networks and compares the scheduler-based scheme
with AEDCF. The paper is concluded by a discussion on how to extend the evaluation to multi-hop wireless networks
and examine the role of the routing layer and the MAC layer.
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