Energy saving in multi-standard mobile terminals through short-range cooperation

Multi-standard mobile devices are allowing users to enjoy higher data rates and ubiquitous connectivity. These advances are achieved on the expense of higher energy consumption requirements due to the continuous connectivity and the multiple active wireless interfaces. In this article, we use one advantage of the multiple interfaces, namely short-range (SR) communications. Mobile terminals (MTs) use SR cooperative networking to take advantage of the good channel quality of SR links to save energy in multi-standard MTs. In this cooperative network, the combined energy of all MTs is treated as a pool of resources, which is used by all MTs in the network. Towards this end, we propose using cooperation between MTs using SR technology to achieve energy savings. We conduct a quantitative numerical analysis to show the energy saving gains that can be achieved. We derive the energy gains in different use cases, considering different combinations of technologies (WiFi-WiMedia, WiMAX-WiFi and WiFi-WiFi) and different channel conditions. We show that up to 80% energy savings can be achieved when using a combination of WiMedia as SR and WiFi as long-range technology, compared to using WiFi without cooperation. We also show that SR cooperation can be used to extend the lifetime of the whole network. In such scenario, terminals, which are running out of battery or low in energy, can still relay their data through other MTs, even if this will result in a slight increase in the total consumption of all MTs. This way, source MTs with low battery level benefit from the good condition of the SR channel, extending the lifetime of their batteries. The increase in the energy consumption of the relays can hence be compensated by some kind of payment, which opens opportunities for new business models involving source MTs, relays and network operators.