Weighted Max-Min Resource Allocation for Frequency Selective Channels

In this paper, we discuss the computation of weighted max-min rate allocation using joint TDM/FDM strategies under a PSD mask constraint. We show that the weighted max-min solution allocates the rates according to a predetermined rate ratio defined by the weights, a fact that is very valuable for telecommunication service providers. Furthermore, we show that the problem can be efficiently solved using linear programming. We also discuss the resource allocation problem in the mixed services scenario where certain users have a required rate, while the others have flexible rate requirements. The solution is relevant to many communication systems that are limited by a power spectral density mask constraint such as WiMax, Wi-Fi and UWB

The effect of directional antennas on slotted CSMA ad hoc networks

The performance of wireless ad hoc network are mostly lim-ited by the self interference caused by the network members. Smart antennas and carrier sensing multiple access (CSMA) have been considered separately as efficient methods for self-interference reduction. In this paper we analyze the effect of directional antennas on the transmission capacity of slotted CSMA networks. The analysis is based on a Poisson point process shot noise model for the aggregate interference. The effect of directional antennas is shown to be equivalent to net-work density scaling. This scaling is expressed through a sin-gle parameter, which depends only on the antenna and the channel exponential decay factor. The paper also presents a useful bound on rate ratio of a pair of slotted CSMA networks. This bound is used to demonstrate the transmission capacity gain of slotted CSMA over slotted ALOHA networks. In par-ticular it is shown that if the antennas have very narrow beams then the advantage of CSMA over ALOHA is negligible. 1