Analysis of the 2-hop time division relaying system performance with optimal power allocation

Relaying is an effective way to combat channel fading, improve channel capacity and enlarge the coverage. Some link level analyses have been made before, and the optimal power allocation (OPA), which can further improve the power efficiency, is derived and verified. In this paper, some problems concerning the application of the relaying techniques to the real networks are discussed. The performance is evaluated for a single cell in terms of average SNR where the circular cell geometry is assumed. TDMA is assumed and the relaying stations (RS) use different time slots to distinguish the signals receiving from the transmitter (TX) and transmitting to the receiver (RX). Firstly, the maximum performance gain is derived as an upper bound when mobile terminals are enabled to serve as RSs for other terminals. Secondly, the performance of a more practical scenario is taken into account, which adopts fixed RSs (FRS). Besides, an idea of virtual RSs (VRS) is still developed as a bound on the FRS performance. Through simulations, it is verified that the performance of FRS is worse than that using mobile RSs (MRS), and VRS is a tradeoff method between the MRS and FRS, which accords with FRS when the number of RS is large. Therefore, VRS can be used to estimate the performance of FRS in a much simpler way through numerical integral.