Green radio communications in a heterogeneous wireless medium

Recently there has been a growing interest in developing energy efficient wireless communication networks, due to environmental, financial, and quality-of-experience considerations, for both mobile users and network operators. The developed solutions in this regard are referred to as green communications, so as to reflect the importance of their environmental dimension. Great potential for energy efficient communications lies in today's heterogeneous wireless medium with overlapped coverage from different networks, given the vast diversity in fading channels and propagation losses among mobile terminals and base stations, and in available resources and operating frequency bands at different networks. In such a networking setting we propose a joint bandwidth and power allocation approach for uplink and downlink communications that can promote energy savings for both mobile users and network operators. We discuss several challenging issues, including design and implementation issues. In addition, we present a case study of uplink communications for illustration purposes.