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: 2.62). 12/2010; DOI: 10.1109/TIT.2010.2070271 Source: IEEE Xplore

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 
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 · 2.42 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: In this dissertation, adaptive power control for single and multiuser opportunistic systems is investigated. First, a new adaptive powercontrolled diversity combining scheme for single user systems is proposed, upon which is extended to the multiusers case. In the multiuser case, we first propose two new threshold based parallel multiuser scheduling schemes without power control. The first scheme is named onoff based scheduling (OOBS) scheme and the second scheme is named switched based scheduling (SBS) scheme. We then propose and study the performance of thresholdbased power allocation algorithms for the SBS scheme. Finally, we introduce a unified analytical framework to determine the joint statistics of partial sums of ordered RVs with i.i.d. and then the impact of interference on the performance of parallel multiuser scheduling is investigated based on our unified analytical framework.
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