Optimal Channel Pairing and Power Allocation for Multi-channel Multi-hop Relay Networks
We study the problem of channel pairing and power allocation in a multi-channel, multi-hop relay network to enhance the end-to-end data rate. OFDM-based relays are used as an illustrative example, and the amplify-and-forward and decode-and-forward relaying strategies are considered. Given fixed power allocation to the OFDM subcarriers, we observe that a sorted-SNR subcarrier pairing strategy is data-rate optimal, where each relay pairs its incoming and outgoing subcarriers by their SNR order. For the joint optimization of subcarrier pairing and power allocation, we show that it is optimal to separately consider the two subproblems, for both individual and total power constraints. This separation principle significantly reduces the computational complexity in finding the jointly optimal solution. We further establish the equivalence between sorting SNRs and sorting channel gains in the jointly optimal solution, which allows simple implementation of optimal subcarrier pairing at the relays. Simulation results are presented to demonstrate the performance gain of the jointly optimal solution over some suboptimal alternatives.
KeywordsOrthogonal Frequency Division Multiplex Power Allocation Relay Node Channel Gain Orthogonal Frequency Division Multiplex System
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- 1.Hottinen, A., Heikkinen, T.: Subchannel assignment in OFDM relay nodes. In: Annual Conf. on Information Sciences and Systems, Princeton, NJ (March 2006)Google Scholar
- 2.Herdin, M.: A chunk based OFDM amplify-and-forward relaying scheme for 4g mobile radio systems. In: Proc. IEEE Int. Conf. Communications (ICC), vol. 10 (June 2006)Google Scholar
- 3.Li, Y., Wang, W., Kong, J., Hong, W., Zhang, X., Peng, M.: Power allocation and subcarrier pairing in OFDM-based relaying networks. In: Proc. IEEE Int. Conf. Communications (ICC) (May 2008)Google Scholar
- 4.Shen, Z., Wang, X., Zhang, H.: Power allocation and subcarrier pairing for OFDM-based AF cooperative diversity systems. In: Proc. IEEE Vehicular Technology Conf, VTC (April 2009)Google Scholar
- 5.Vandendorpe, L., Duran, R., Louveaux, J., Zaidi, A.: Power allocation for OFDM transmission with DF relaying. In: Proc. IEEE Int. Conf. Communications, ICC (2008)Google Scholar
- 7.Hajiaghayi, M., Dong, M., Liang, B.: Using limited feedback in power allocation design for a two-hop relay OFDM system. In: Proc. IEEE Int. Conf. Communications (ICC), vol. 2 (June 2009)Google Scholar
- 8.Wang, W., Yan, S., Yang, S.: Optimally joint subcarrier matching and power allocation in OFDM multihop system. EURASIP J. Appl. Signal Process, USA (March 2008)Google Scholar
- 10.Zhang, X., Gong, Y.: Adaptive power allocation for multi-hop OFDM relaying systems. In: Int. Conf. on Infor., Commun., Signal Processing, ICICS (2007)Google Scholar
- 11.Zhang, X., Jiao, W., Tao, M.: End-to-end resource allocation in OFDM based linear multi-hop networks. In: Proc. IEEE INFOCOM (2008)Google Scholar
- 13.Laneman, J., Wornell, G., Tse, D.: An efficient protocol for realizing cooperative diversity in wireless networks. In: Proc. IEEE Int. Symp. on Infor. Theory, ISIT (2001)Google Scholar