Selection of channel coding for low-power wireless systems

The wireless communications world is moving towards the so-called 4G picture, by integrating many different subsystems. Some of them have to provide short-range connectivity at very low power, in order to enable battery-operated sensors or devices. This low-power requirement can be achieved by selecting channel codes of high coding gain. However, the power consumption of encoding and decoding operations also has to be taken into account. This paper analyzes this trade-off between coding gain and digital power consumption, considering different wireless scenarios. It shows that turbo codes can be used even for relatively low-power applications. For very low-power systems, simple Hamming codes provide a good trade-off, as well as convolutional codes. The Golay code is another strong candidate, thanks to a very efficient implementation. Considering current CMOS technology, the different codes are in competition for systems sending bits with an energy between 0.1 and 10 nJ. Systems working at lower values do not gain anything in coding, while systems working above will always advantageously use turbo-codes.