DMCA
Aggregation with Fragment Retransmission for Very
BibTeX
@MISC{Wlans_aggregationwith,
author = {High-speed Wlans and Tianji Li Qiang Ni and Yang Xiao and Senior Member and Thierry Turletti},
title = {Aggregation with Fragment Retransmission for Very},
year = {}
}
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Abstract
Abstract — In upcoming very high-speed WLANs the physical layer (PHY) rate may reach 600 Mbps. To achieve high efficiency at the medium access control (MAC) layer, we identify fundamental properties that must be satisfied by any CSMA/CA based MAC layer and develop a novel scheme called Aggregation with Fragment Retransmission (AFR). In the AFR scheme, multiple packets are aggregated into and transmitted in a single large frame. If errors happen during the transmission, only the corrupted fragments of the large frame are retransmitted. An analytic model is developed to evaluate the throughput and delay performance of AFR over a noisy channel, and to compare AFR with competing schemes in the literature. Optimal frame and fragment sizes are calculated using this model. Transmission delays are minimised by using a zero-waiting mechanism where frames are transmitted immediately once the MAC wins a transmission opportunity. We prove that zerowaiting can achieve maximum throughput. As a complement to the theoretical analysis, we investigate by simulations the impact of AFR on the performance of realistic application traffic with diverse requirements. We have implemented the AFR scheme in the NS-2 simulator and present detailed results for TCP, VoIP and HDTV traffic. The AFR scheme described was developed as part of the 802.11n working group work. The analysis presented here is general enough to be extended to the proposed scheme in the upcoming 802.11n standard. Trends indicated by our simulation results should extend to any well-designed aggregation scheme.
Keyphrases
fragment retransmission afr scheme ns-2 simulator medium access control corrupted fragment csma ca realistic application traffic afr scheme described optimal frame novel scheme theoretical analysis mac layer zero-waiting mechanism analytic model single large frame delay performance high efficiency noisy channel well-designed aggregation scheme diverse requirement maximum throughput transmission opportunity fragment size group work present detailed result physical layer transmission delay hdtv traffic high-speed wlan simulation result large frame multiple packet fundamental property
