Acta Metallurgica Sinica(English letters) ›› 2011, Vol. 18 ›› Issue (1): 9-15.doi: 10.1016/S1005-8885(10)60021-0

• Wireless • Previous Articles     Next Articles

Optimal power allocation for two-way relaying over OFDM using physical-layer network coding

  

  • Received:2010-05-10 Revised:2010-11-09 Online:2011-02-28 Published:2011-02-28
  • Contact: WANG De-sheng E-mail:dswang@hust.edu.cn

Abstract:

In this paper, a network scenario of two-way relaying over orthogonal frequency division multiplexing (OFDM) is considered, in which two nodes intend to exchange the information via a relay using physical-layer network coding (PLNC). Assuming that the full channel knowledge is available, an optimization problem, which maximizes the achievable sum rate under a sum-power constraint, is investigated. It is shown that the optimization problem is non-convex, which is difficult to find the global optimum solution in terms of the computational complexity. In consequence, a low-complexity optimal power allocation scheme is proposed for practice implementation. A link capacity diagram is first employed for power allocation on each subcarrier. Subsequently, an equivalent relaxed optimization problem and Karush-Kuhn-Tucker (KKT) conditions are developed for power allocation among each subcarrier. Simulation results demonstrate that the substantial capacity gains are achieved by implementing the proposed schemes efficiently with a low-complexity computational effort.

Key words:

two-way relaying, power allocation, physical-layer network coding, OFDM