Relay selection and resource allocation for multi-user cooperative LTE-A uplink

Cooperative relaying is a promising technique for Long Term Evolution Advanced (LTE-A) networks to satisfy high throughput demand and support heterogeneous communication services with diverse quality-of-service (QoS) requirements. However, efficient relay selection as well as resource allocation are critical in such a network when multiple users and multiple relays are considered. In this paper, a resource allocation problem of maximizing the total achievable throughput for multi-user cooperative LTE-A uplink system considering heterogeneous services is investigated. An optimal joint relay selection, subcarrier assignment and power allocation scheme under total power constraint is proposed. The optimization problem is formulated as a convex optimization problem and solved by decomposing it into a hierarchy of subproblems with reduced computational complexity. The subgradient method is used to find the Lagrange multipliers, which helps to obtain the optimal solution. Numerical results show that our approach supports heterogeneous services while guaranteeing each user´s QoS requirements with slight total system throughput degradation.