Rate adaptive resource allocation with fairness control for OFDMA networks

The use of opportunistic radio resource allocation techniques in order to efficiently manage the resources generates a low fairness among the users in a cellular system due to uneven Quality of Service (QoS) distribution. Some classic rate adaptive policies tried to tackle this problem for OFDMA systems by proposing solutions to maximize capacity, maximize fairness, or find a static trade-off between these two objectives. This work generalizes these classic policies and propose a dynamic fairness/rate adaptive technique based on dynamic sub-carrier assignment and equal power allocation that considers a new fairness constraint in the optimization problem. By means of extensive system-level simulations, it is demonstrated that the proposed technique is able to provide an instantaneous (short-term) fairness control, which provides to the network operator the flexibility to operate on any desired trade-off point.Peer ReviewedPostprint (published version

Low Complexity Scalable Iterative Algorithms for IEEE 802.11p Receivers

In this paper, we investigate receivers for Vehicular to Vehicular (V2V) and Vehicular to Infrastructure (V2I) communications. Vehicular channels are characterized by multiple paths and time variations, which introduces challenges in the design of receivers. We propose an algorithm for IEEE 802.11p compliant receivers, based on Orthogonal Frequency Division Multiplexing (OFDM). We employ iterative structures in the receiver as a way to estimate the channel despite variations within a frame. The channel estimator is based on factor graphs, which allow the design of soft iterative receivers while keeping an acceptable computational complexity. Throughout this work, we focus on designing a receiver offering a good complexity performance trade-off. Moreover, we propose a scalable algorithm in order to be able to tune the trade-off depending on the channel conditions. Our algorithm allows reliable communications while offering a considerable decrease in computational complexity. In particular, numerical results show the trade-off between complexity and performance measured in computational time and BER as well as FER achieved by various interpolation lengths used by the estimator which both outperform by decades the standard least square solution. Furthermore our adaptive algorithm shows a considerable improvement in terms of computational time and complexity against state of the art and classical receptors whilst showing acceptable BER and FER performance