Frequency domain joint estimation of synchronization parameter and channel impulse response in composite radio receiver

In this paper, an innovative frequency domain joint estimation algorithm of synchronization parameter and channel impulse response (CIR) in Direct Sequence Code Division Multiple Access (DS-CDMA) system is proposed. This algorithm is based on the expectation-maximization (EM) method. Because this algorithm can provide accurate estimation of channel conditions and synchronization parameter for DS-CDMA receivers, even with a simple equalization module, for example, a one-tap multiplier based frequency domain equalizer (FDE), a receiver architecture following this approach can still provide better performance than the costly multi-tap multiplier based equalizer, such as the time domain equalizer (TDE). Performance is well maintained under fast fading channel for mobile stations at high velocity. Moreover, a generic receiver architecture purely based on frequency domain equalization for a composite radio environment, that is CDMA and Orthogonal Frequency-Division Multiplexing (OFDM) systems, is also proposed in this paper. This architecture can be readily implemented by software defined radio (SDR) technology. Our results manifest that this adaptive receiver architecture is very promising and can achieve good performance with low cost.