Iterative Receiver with EM Channel Estimation and CDMA Turbo Coding

1 In a conventional communication system with a turbo decoder, the received signal strength is measured at the receiver front end, but not the noise-power spectral density. Hence, the accuracy of the estimated bit energy-to-noise-spectral-density ratio can be poor, which degrades the turbo decoder. This paper presents an efficient iterative code-division multiple-access direct-sequence system that uses a turbo code. The signal strength and the noise-power spectral density are separately estimated by applying the expectation maximization algorithm. The higher throughput of the proposed system relative to a conventional 3 rd Generation Partnership Project system is verified through simulations using a Jakes fading environment. The complexity of the proposed iterative parameter-estimation scheme is simple because the required number of complex multiplications is equal to only four times the fading block size.