Energy-efficient turbo decoder

Turbo codes have been recently adopted in the next generation of wideband CDMA standards. These codes achieve superior performance at the expense of high computational complexity. This makes their low energy implementation a very important yet challenging problem. In this paper we study the effect of different approximation techniques such as pruning the trellis, reducing the number of states, sliding window, early termination on the Bit Error Rate (BER) and energy consumption for a Turbo decoder implemented on a general purpose processor. We show that a combination of these techniques can result in 66.5% energy reduction for a log-MAP based Turbo decoder if a loss of 1.4 dB in SNR can be tolerated at BER = 10⁻⁵.