Article
An MGFBased Unified Framework to Determine the Joint Statistics of Partial Sums of Ordered Random Variables
Dept. of Electr. & Comput. Eng., Texas A&M Univ., College Station, TX, USA
IEEE Transactions on Information Theory (Impact Factor: 2.65). 12/2010; DOI: 10.1109/TIT.2010.2070271 Source: IEEE Xplore

Conference Paper: Impact of interference on the performance of selection based parallel multiuser scheduling
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ABSTRACT: In this paper, we investigate the impact of interference on the performance of selection based parallel multiuser scheduling. In conventional parallel multiuser scheduling schemes, every scheduled user is interfering with every other scheduled user. This is a factor which limits the capacity and performance of multiuser systems and the level of interference becomes substantial as the number of scheduled users increases. Based on the above motivation, we investigate the tradeoff between the throughput and the number of scheduled users. The major difficulty in the total average sum rate capacity and the average spectral efficiency (ASE) analysis resides in the determination of the statistics of the Signal to Interference Plus Noise Ratio (SINR) of the scheduled user. Fortunately, we could derive the accurate statistical characterization of the SINR of the scheduled user. With these accurate statistical analysis, we derive the total average sum rate capacity and the average spectral efficiency based on the SINR. Based on the ASE and the total average sum rate capacity analysis, we investigate the tradeoff between the throughput and the number of scheduled users. Hence, based on these results, the system should carefully select the appropriate number of scheduled users to maximize the overall throughput while maintaining an acceptable quality of service given certain channel conditions.Information Theory and Its Applications, 2008. ISITA 2008. International Symposium on; 01/2009  [Show abstract] [Hide abstract]
ABSTRACT: Spread spectrum receivers with generalized selection combining (GSC) RAKE reception were proposed and have been studied as alternatives to the classical two fundamental schemes: maximal ratio combining and selection combining because the number of diversity paths increases with the transmission bandwidth. Previous work on performance analyses of GSC RAKE receivers based on the signal to noise ratio focused on the development of methodologies to derive exact closedform expressions for various performance measures. However, some open problems related to the performance evaluation of GSC RAKE receivers still remain to be solved such as the exact performance analysis of the capture probability and an exact assessment of the impact of selfinterference on GSC RAKE receivers. The major difficulty in these problems is to derive some joint statistics of ordered exponential variates. With this motivation in mind, we capitalize in this paper on some new order statistics results to derive exact closedform expressions for the capture probability and outage probability of GSC RAKE receivers subject to selfinterference over independent and identically distributed Rayleigh fading channels, and compare it to that of partial RAKE receivers.IEEE Transactions on Communications 08/2011; 59:22412253. · 1.98 Impact Factor 
Conference Paper: Limiting behavior of receive antennae selection
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ABSTRACT: In this paper we investigate the limiting behavior of receive antenna selection in singleinput multipleoutput (SIMO) wireless systems when the number of receive antennas gets very large. Using results on the convergence of the trimmed mean, we show that mutual information converges in distribution to the logarithm of a folded Gaussian distribution in the limit of a large number of receive antennas. The convergent distribution also shows there is channel hardening in this scenario like SIMO maximum ratio combining. For finite number of receive antennas, N, we derive the exact outage probability for SIMO with selecting the best S receive antennas. This outage probability analysis is used to study the rate of convergence of the mutual information, which reveals that the rate of convergence increases with the number of selected receive antennas in medium and high SNR regimes and decreases in the low SNR regime. We also show that the multiuser scheduling gain at low SNR is proportional to the square root of number of selected receive antennas, √S, in the limit of large number of users. These results could be useful in designing nextgeneration wireless systems, such as 4G, where the requirements are to increase the transmission rate by increasing the number of antennas and at the same time decreasing the complexity of the system.Information Sciences and Systems (CISS), 2011 45th Annual Conference on; 04/2011
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