No abstract

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.

This paper introduces a new approach to providing secure physical-layer massive multipleinput multiple-output (MIMO) based communications that can improve the energy efficiency of the system. This is achieved by synthesizing orthogonal artificial noise (AN) that has to be constrained to lie in the null space of the legitimate users' channels while it should lie in the range space of the eavesdropper's channel. In addition, this AN reduces the peak-to-average power ratio (PAPR) of the transmit signal. Indeed, low PAPR signals are preferable and more efficient for low-cost hardware, thus improving the energy consumption of massive MIMO systems. In this paper, we propose a new PAPR-aware precoding scheme based on the use of AN to enhance the secrecy performance of massive MIMO while reducing the PAPR of the transmit signal and guaranteeing excellent transmission quality for legitimate users. The scheme is formulated as a convex optimization problem that can be resolved via steepest gradient descent (GD). Accordingly, we developed a new iterative algorithm, referred to as PAPR-Aware-Secure-mMIMO, that makes use of instantaneous information to solve the optimization problem. Simulation results show the efficiency of our proposed algorithm in terms of PAPR reduction and secrecy, which is also studied with respect to power distribution between useful signal and AN, PAPR targets and the number of BS antennas.INDEX TERMS Artificial noise (AN), massive multiple-input multiple-output (MIMO), peak-to-average power ratio (PAPR), physical layer security (PLS), power allocation, steepest gradient descent (GD), zeroforcing (ZF) precoding.

This work proposes two new Resource Block (RB) allocation algorithms for the LTE uplink. They take into account the RB adjacency constraint and update the allocation metric. Two different heuristics are proposed: an Opportunistic and Efficient RB allocation Algorithm (OEA) and a Quality of Service based Opportunistic and Efficient RB allocation Algorithm (QoS based OEA). Both algorithms seek to maximize the aggregate throughput and avoid RB wastage unlike other algorithms in the literature. The complexity of the proposed algorithms are also computed analytically and compared to other well known heuristics.