The wireless standard IEEE 802.15.4 is emerging as a key enabling technology for different wireless sensor network applications. IEEE802.15.4 supports a low data rate wireless sensor network with low power requirement. In this paper, we discuss the performance analysis of IEEE 802.15.4 MAC assuming star topology in the beacon enabled mode. We obtain analytical expressions for channel sensing probabilities and saturation throughput during the contention access period. We have included the packet discard analysis and validated the analytical expressions for these parameters using ns-2 simulation. Further, we also discuss the performance analysis of the MAC when the contention access mechanism of IEEE 802.15.4 is modified to have only one channel sensing. Finally, we discuss adaptation of the frame length for the case with one channel sensing.

UWB is an emerging technology inviting major advances in wireless communication, networking, radar and positioning systems. In this paper, we present novel algorithms for the multiuser detection based on minimum mean square error (MMSE) for a DS-UWB multiuser communication system. The algorithms exploit the inherent multipath diversity and also mitigate the effects of both inter symbol interference(ISI) and multiuser interference (MUI). Simulation results show that the given algorithms perform better than the other known detectors in literature. We also provide closed form expression for the BER results of the above scheme

In this paper, we examine binary hypothesis testing and parameter estimation problem in a sensor network. We address the problem of detection and also the estimation of the underlying parameter at the fusion center by optimally combining the test statistics sent by different sensors. We make no assumptions on the noise statistics at the sensor nodes except that their first and second order statistics are known. We show that the proposed method is optimal as an estimator as well as a detector.

In this correspondence, we consider a problem of optimal source, channel coding rate pair allocation over a wireless link based on the channel fading state and the queue length of the transmitter. The source is delay sensitive. Therefore, our objective is to minimize the mean delay under given mean power and distortion constraints. We show that by jointly optimizing the source and channel rates, one can gain substantially in performance as compared to only source or channel rate optimization, as is usually considered in the literature. This is shown for single user, single-input-single-output (SISO), multiple-input-multiple-output (MIMO), and multiuser systems. The methods used are from Markov decision theory