High Energy Efficiency Transmission in MIMO Satellite Communications

In this paper, we propose a high energy efficiency transmission scheme in multi-beam MIMO satellite systems. Satellite is regarded as a two-way decode-and- forward (DF) relay, where multiple pairs of users exchange information within pair. Zero-forcing transceivers are employed at the satellite. The challenge is that of deriving an accurate yet tractable expression of the system-level energy efficiency (EE) to be used as our objective function. To tackle this challenge, firstly, a closed-form expression of the EE is derived under the assumption of perfect satellite channel. Secondly, based on this analytical expression, we formulate a resource allocation optimization problem for the EE maximization by jointly optimizing satellite power and users power, subject to limited transmit power and minimum quality-of-service (QoS) constraints. Finally, the successive convex approximation technique is invoked to transform the original optimization problem into a concave fractional programming problem, which is then efficiently solved by the existed methods. Simulation results demonstrate the effectiveness of the proposed algorithms.