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Abstract-Among the several features that are foreseen for increasing the capacity of cellular systems, Multi-user multipleinput multiple-output (MU-MIMO) is considered as a key enabling technology. Particularly, MU-beamforming is a powerful means of increasing the system capacity and throughput by creating several spatial signals to different users on the same time/frequency resource. In this paper, we develop an analytical model for MU-beamforming based on queuing theory combined with network simulations. The proposed framework is used for evaluating the potential gains in terms of capacity and throughput in LTE-Advanced system. Several scenarios are studied, with and without beamforming. Results show an important gain of SU-beamforming over the classical system without beamforming and a further gain of MU-beamforming, especially at high loads.

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Vehicular networks are a promising field in wireless networks enabling connection vehicles among themselves or between a vehicle and an infrastructure. These networks aim to offer several potential applications ranging from road safety applications and driver assistance to infotainment. However, these networks have limited coverage and capacity. Among the options that may help overcome these limitations, we can quote cooperative communications and analog network coding (ANC). The idea of this paper is to combine these two concepts in order to improve the vehicular network connectivity and capacity. The proposed solution is divided into three stages. The first stage aims at identifying the coding and relaying opportunities. The second stage uses a distributed scheme to select the Best Vehicular Relay among potential candidates when relaying is required, while the last stage performs our joint relaying and coding strategy on the received signals. In order to validate our approach, numerical analysis is performed to evaluate the performances in terms of raw Bit Error Rate (BER) and throughput. This confirmed our expectation showing that cooperative relaying achieves better performance than the direct transmission in terms of raw BER but decreases the throughput. However, by deploying analog network coding on the Best Vehicular Relay, the throughput is improved considerably at the price of a slight deterioration of the raw BER.