Acta Metallurgica Sinica(English letters) ›› 2015, Vol. 22 ›› Issue (5): 56-62.doi: 10.1016/S1005-8885(15)60681-1

• Wireless • Previous Articles     Next Articles

Energy efficient joint power and subcarrier assignment scheme in OFDM relay system


  1. College of Telecommunications & Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
  • Received:2014-12-05 Revised:2015-03-22 Online:2015-10-30 Published:2015-10-30
  • Supported by:
    This work was supported by National Natural Science Foundation of China (61171094), National Basic Research Program of China (973 program: 2013CB329005).

Abstract: A power and subcarrier assignment algorithm is proposed in this paper for maximizing the energy efficiency in the single-relay multi-users orthogonal-frequency-division -multiplexing (OFDM) systems. Under the constraints of maximum total power and minimum transmission rate, we formulate a joint optimization scheme for subcarrier pairing and power allocation to maximize the energy efficiency. The Dinkelbach’s method is used to depress the complexity and to transform the problem to a linear programming, then we use the dual decomposition approach solve the problem. In the premise of the system transmission rate, this algorithm uses the improved decode-and-forward (IDF) relay to maximize the system energy efficiency. Simulation results illustrate that,compared with the spectral-efficient maximization (SEM) algorithm, the energy-efficient maximization (EEM) algorithm proposed in this paper makes the energy efficiency not decline when the signal-to-noise radio (SNR) is at a high level. At the point where SNR is 10 dB and the number of subcarriers is 16, system energy efficiency is increased by 6.2% and 11.9% with the subcarrier pairing strategy and power allocation strategy respectively.

Key words: energy efficiency, green communications, multi-user orthogonal-frequency-division -multiplexing (OFDM), subcarrier pairing, power allocation