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More and more video application are being carried on wireless systems with the development of the smart phones. However, the performance of these applications is lack of study, especially for the most advanced LTE networks. In this paper, we investigate the performance of the video telephony over the LTE downlink systems with and without QoS provisioning. The simulation results using two classical...
Cognitive radio (CR) networks are designed to utilize the licensed spectrum when it is not used by the primary (licensed) users. In this paper, we investigate how a CR user senses multiple channels and determine the optimal transmission duration and power allocation. When performing optimization, we take energy efficiency, throughput, and interference with the primary users into consideration and...
In this paper, we propose probability-based resource allocation in cognitive radio (CR) networks to exploit the flexibility of opportunistic spectrum access (OSA). Assisted by the statistical information acquired from spectrum sensing, the proposed approach maximizes the overall utility of CR users and ensures sufficient protection of licensed users from unacceptable interference. It also supports...
In OFDMA systems, reducing the inter-cell interference among adjacent cells is a very important issue especially for the cell-edge users. In this paper, we propose a distributed algorithm that maximizing the system total throughput considering proportional fairness. In our proposed algorithm, the frequency resources in each cell is divided into high and low power regions. The bandwidth allocations...
Multiuser systems can provide multiuser diversity gains by assigning channels to users with higher channel gains. To avoid the extensive information exchange with the access point for the uplink access in centralized approaches, we propose in this paper a distributed opportunistic access scheme. Through a judicious design of a novel backoff mechanism to utilize the channel information and reduce collisions,...
In this paper, we compare the downlink capacity and throughput between the variable spreading factor-orthogonal frequency and code division multiple access (VSF-OFCDMA) with one-cell frequency reuse, and the orthogonal frequency division multiple access (OFDMA) with conventional three-cell frequency reuse. Since the multiuser diversity gain in OFDMA systems can be achieved by approximately designing...
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