We address the problem of co-channel interference (CCI) in wireless mesh networks based on the IEEE802.11s extension. The carrier sensing mechanism deployed in those networks insufficiently addresses the CCI problem, causing the hidden and exposed node problems; consequently degrading the throughput and latency. In this paper, we show how beamforming techniques can be implemented on top of the IEEE802.11s medium access control protocol and, using the information readily available, cancel the interference to mitigate this inefficiency of carrier sense and improve the spatial-reuse gain. In addition, we propose the signal-to-jamming-noise ratio (SJNR) beamformer and show that it significantly improves the spatial-reuse gain compared to the simple zero-forcing (ZF) beamformer and the basic IEEE802.11s access scheme. We derive the ergodic capacity of the ZF beamformer and the basic IEEE802.11s access scheme and simulate the performance of the various schemes. We show that improvements of up to 85% are achieved as function of the scenario simulated and the beamforming technique used and that the SJNR scheme outperforms the standard ZF beamformer.
The demand for wireless broadband access is rapidly growing. Consequently, the need for wireless systems offering both high speed data rates and high mobility access will become more and more important for present and future communication systems. An interesting candidate to fulfill those requirements is the OFDMA-based IEEE 802.16e wireless metropolitan area network system. In this paper, we study the possible implementation of the Mesh topology for the IEEE 802.16e standard. The reuse of the TDD frame structure considered in the point-to-multipoint topology will be discussed. The performance of the OFDMA air interface will be analyzed, for a varying spectral reuse factor and for different carrier allocations amongst the users.
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