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The energy efficiency in wireless networks is currently a central concern of research. We propose in this paper a new energy efficiency scheme which allocates the mobile's transmission power in function of the allocated Resource Blocks (RB) and the channel conditions of the user on the allocated RBs. We focus on the energy efficiency of the Opportunistic and Efficient Resource Block Allocation (OEA) algorithm and its variant adapted to the Quality of Service (QoS) of the traffics: the QoS based OEA for LTE uplink networks. The OEA and the QoS based OEA allocate the RBs to UEs efficiently and with respect to the SC-FDMA constraints, such that, for one user, contiguous RB are allocated, and the same Modulation and Coding Scheme (MCS) is used over the whole allocated RBs. Once RBs are allocated to UEs, power control is then applied to the mobile's transmission power considering the MCS used and the channel conditions. This energy efficiency allows users to achieve the same throughput than before the power control and does not affect the MCS selection established at the RB allocation step. This new scheme allows the transmission of a high number of bits per Joule.

International audienceFrequency reuse is an important topic in wireless communications systems. In this paper, we address the issue of frequency reuse in sectored cells which are subject to interference in the overlap regions of adjacent sectors. We propose to increase the number of sectors from 3 to 4 using conventional base station sector antennas with beam-width exceeding 120deg, which purposely creates large overlap regions between adjacent sectors. Rather than treating the signals of adjacent sectors as interference, we investigate sector cooperation for communication with users located in the overlap regions. Different scenarios are considered for user locations, and simulation results are given which illustrate the performance of the proposed schemes

This paper addresses multiple access in MIMO wireless networks. It compares two distributed interference alignment techniques, in space and in frequency, that both aim at removing interferences through orthogonalization. The theoretical advantages and drawbacks of each technique are highlighted. Then, the multiplexing gain and the computational complexity are analytically evaluated. It is shown that frequency interference alignment achieves a higher multiplexing gain than space interference alignment in realistic network conditions, and always requires a lower computational complexity. Finally, the performances of both algorithms with varying number of interfering links are assessed via numerical simulations. Space interference alignment fulfills complete interference suppression, and consequently provides the same spectral efficiency to all links, regardless of the number of interfering links. Frequency interference alignment is less efficient in terms of INR, and the spectral efficiency per link thus decreases when the number of links increases. Nevertheless, the spectral efficiency is always higher with frequency interference alignment than with space interference alignment.