Feedback based relaying in long term evolution systems

The last ten years have witnessed explosive growth in the number of subscribers for mobile telephony and data services. However, the recent development of mobile broadband technology comes at a significant energy cost. As subscriber levels saturate, the operating costs of such a network need to be reduced significantly to maintain competitiveness. The carbon footprint will become an increasingly important constraint in future system design. The objective of the recently started Mobile VCE Core 5 Green Radio programme is to study in depth the energy consumption issues for wireless networks. The project considers two main themes, tackling both the top level design of future wireless networks and how to optimise the constituent elements of wireless devices. This paper considers new transmission protocols that maximize the lifetime of a network under a Quality-of-Service (QoS) constraint. The proposed schemes incorporate a Decode-and-Forward relaying strategy with instantaneous channel feedback in order to save energy and therefore prolong the network lifetime. We provide examples of the savings offered by the proposed techniques in significantly increase the lifetime of the network without affecting the considered QoS and delay constraints. The methods seem to be promising solutions for Green Radio technology.