Construction of low-rate power-efficient coding schemes and their application to CDMA

We propose a novel design method, which is an extension to the EXIT charts introduced by ten Brink (see IEE Electronics Letters, vol.35, no.10, p. 806-808, 1999), for low-rate power-efficient codes. An exemplary design of a rate -1/4 code shows more than 1 dB more coding gain than the original turbo-code of rate -1/2. Using this code in a CDMA scheme while reducing the spreading by a factor of 2 helps improving the overall performance of the multi-user scheme significantly.