Energy efficiency of error correcting mechanisms for wireless communications

We consider the energy efficiency of error control mechanisms for wireless communication. Since high error rates are inevitable to the wireless environment, energy efficient error control is an important issue for mobile computing systems. Although good designed retransmission schemes can be optimal with respect to energy efficiency, they can introduce problems to fulfill the required QoS of an application. Since the channel conditions and the requirements vary dynamically, we concentrate on adaptive implementations of error correction mechanisms. Error correction mechanisms traditionally optimize the performance and provide an optimal solution to withstand all possible errors. In the context of energy consumption we have studied the energy efficiency of three different error correction mechanisms and have implemented these in software. We show that the energy efficiency trade-off between error correction and communication can have a great impact on the energy efficiency of a system. It will be shown that from energy efficiency perspective it is not always profitable to minimize the number of bits transmitted over the air. A general strategy will be provided that can be used to determine an energy efficient error correction scheme of a minimal system consisting of a general-purpose processor and a wireless interface. As an example we have investigated a system with a WaveLAN card as wireless interface.