Channel and queue aware joint relay selection and resource allocation for MISO-OFDMA based user-relay assisted cellular networks

Abstract

User-relay assisted orthogonal frequency division multiple access (OFDMA) networks are cost-effective solutions to meet the growing capacity and coverage demands of the next generation cellular networks. These networks can be used with multiple antennas technology in order to obtain a diversity gain to combat signal fading and to obtain more capacity gain without increasing the bandwidth or transmit power. Efficient relay selection and resource allocation are crucial in such a multi-user, multi-relay and multi-antenna environment to fully exploit the benefits of the combination of user-relaying and multiple antennas technology. Thus, we propose a channel and queue aware joint relay selection and resource allocation algorithm for multiple-input singleoutput (MISO)-OFDMA based user-relay assisted downlink cellular networks. Since, the proposed algorithm is not only channel but also queue-aware, the system resources are allocated efficiently among the users. The proposed algorithm for the MISO-OFDMA based user-relay assisted scheme is compared to existing MISO-OFDMA based non-relaying and fixed relay assisted schemes and it is also compared with the existing single-input single-output (SISO)-OFDMA based user-relay assisted scheme. Simulation results revealed that the proposed scheme outperforms the existing schemes in terms of cell-edge users' total data rate, average backlog and average delay.

Energy-efficient communication for user-relay aided cellular networks with OFDMA

“…The constraint in (13) is the non-negative power constraint. (14) and (15) are the QoS constraints and they ensure that each user has a minimum required data rate. (14) is valid for the inner users and (15) is valid for the celledge users.…”

“…Many resource optimization schemes have been developed in order to meet the increasing demands from the users with limited resources and enhance the performances of the OFDMA based relay-aided cellular networks. Most of these works have focused on either maximizing the system capacity subject to total transmit power or minimizing the total transmitted power subject to minimum data rate allocated to each user [7]- [14]. However, none of these works has provided an energy-efficient solution, since they ignore the energy consumption of the system.…”

“…In [32] and [33], DF user relays were used and EE problem was formed by using individual user rate constraints for an uplink scenario. Although the optimization problems that aim to maximize data rate or to minimize the power [7]- [14] are not effective for EE purpose, [32] and [33] used power minimization for green communication target to simplfy the problem by eliminating the fractional form of the objective function. In [34], the EE maximization problem was applied to the millimeters wave communication systems in which OFDMA was not used.…”