When is FDMA Sum-Rate Optimal in 2x2 Gaussian Interference Channel?

Consider a 2×2 Gaussian interference channel system in a frequency flat environment. We aim to derive sufficient conditions under which frequency division multiple access (FDMA) is optimal, in the objective of sum-rate maximization under power budget constraints of individual users. Two types of conditions are obtained. Briefly, the former one states that the normalized interference channel gain has to be large enough. The corresponding formula can be further extended to K×K (K>2) multi-user scenario. The latter one is that the power budget has to be large enough, even if the normalized interference channel gain is small.

[1]  Chaohuang Zeng,et al.  Efficient water-filling algorithms for a Gaussian multiaccess channel with ISI , 2000, Vehicular Technology Conference Fall 2000. IEEE VTS Fall VTC2000. 52nd Vehicular Technology Conference (Cat. No.00CH37152).

[2]  Zhi-Quan Luo,et al.  Spectrum Management for Interference-Limited Multiuser Communication Systems , 2009, IEEE Transactions on Information Theory.

[3]  Wei Yu,et al.  Optimal multiuser spectrum balancing for digital subscriber lines , 2006, IEEE Transactions on Communications.

[4]  Abhay Parekh,et al.  Spectrum sharing for unlicensed bands , 2005, IEEE Journal on Selected Areas in Communications.

[5]  Wei Yu,et al.  Dual optimization methods for multiuser orthogonal frequency division multiplex systems , 2004, IEEE Global Telecommunications Conference, 2004. GLOBECOM '04..