Minimum estimation and combining generalized selection combining (MEC-GSC)

This paper introduces and analyzes a new adaptive minimum-estimation minimum-combining switched-combining based scheme that reduces considerably the average receiver channel estimation complexity and the power drain from the battery while satisfying a certain desired performance requirement. The mathematical formalism is supported by some selected numerical examples that show that the newly proposed combining scheme can essentially achieve the same performance as competing schemes such as generalized selection combining (GSC) while offering 50 % channel estimation and 75 % processing power savings for some system parameters of interest     

Multi-User Opportunistic Scheduling using Power Controlled Hierarchical Constellations

In this letter, we study an application of hierarchical constellations (known also as embedded, multi-resolution, or asymmetrical constellations) for multi-user opportunistic scheduling. The key idea is to rely on hierarchical constellations to transmit information to two or more best users simultaneously in each transmission. The transmit power as well as the constellation parameter is changed according to the link qualities of the selected users in a way that a given target bit error rate (BER) is satisfied. The expressions for the average transmit power, and the outage probability with truncated channel inversion power control are presented. We also analyze and compare buffer distribution, average buffer occupancy, and packet loss probability of different; schemes via queuing analysis. We finally compare the hierarchical scheme for multi-user scheduling with a uniform constellation-based time-slotted scheme     

Adaptive Modulation over Nakagami Fading Channels

We first study the capacity of Nakagami multipath fading (NMF) channels with an average power constraint for three power and rate adaptation policies. We obtain closed-form solutions for NMF channel capacity for each power and rate adaptation strategy. Results show that rate adaptation is the key to increasing link spectral efficiency. We then analyze the performance of practical constant-power variable-rate M-QAM schemes over NMF channels. We obtain closed-form expressions for the outage probability, spectral efficiency and average bit-error-rate (BER) assuming perfect channel estimation and negligible time delay between channel estimation and signal set adaptation. We also analyze the impact of time delay on the BER of adaptive M-QAM.     

A simple single integral representation of the bivariate Rayleighdistribution

Using an alternate representation of the Marcum Q-function, an expression for the bivariate Rayleigh cumulative distribution function is found in the form of a single integral with finite limits and an integrand composed of elementary functions. This result has advantage over previous forms of the same CDF which involve the Marcum Q-function itself or are expressed as infinite series of products of integrals