Veluppillai Mahinthan

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—We study how to appropriately match users for two-user cooperative-diversity (CD) systems deploying an optimal-power-allocation (OPA) strategy, considering both the amplify and forward and the regenerate and forward CD schemes. The OPA strategies, which can minimize the total energy consumption for the cooperating pair, are derived for both CD schemes.(More)
—In this paper, a cross-layer design of a wireless communication system is proposed by considering a quadrature sig-naling (QS)-based cooperative diversity (CD) system employing truncated stop-and-wait automatic repeat request (ARQ) for error control. The proposed CD-ARQ scheme employs selection relaying at the partner, and all the transmission channels are(More)
— We are concerned with optimally grouping active mobile users in a two-user-based cooperative diversity system to maximize the cooperative diversity energy gain in a radio cell. The optimization problem is formulated as a non-bipartite weighted-matching problem in a static network setting. The weighted-matching problem can be solved using maximum weighted(More)
—This paper presents a novel scheme for the allocation of subcarriers, rates, and power in orthogonal frequency-division multiple-access (OFDMA) networks. The scheme addresses practical implementation issues of resource allocation in OFDMA networks: the inaccuracy of channel-state information (CSI) available to the resource allocation unit (RAU) and the(More)
— A bandwidth and energy efficient cooperative diversity scheme based on quadrature signaling is proposed. The quadrature signaling is achieved by transmitting in the in-phase and quadrature components of QPSK modulation. The diversity gain and the bit error rate of the proposed cooperative diversity scheme improve with the inter-user channel quality. It is(More)
—An adaptive regenerate and forward cooperative diversity (CD) system using quadrature amplitude modulation (QAM) for a two-user cooperation is proposed. The proposed system can achieve a maximum diversity order of two. The bit error probability (BEP) of a CD system depends primarily on the quality of the inter-user channel and user-to-destination channels,(More)