Aiguo Yan

Downlink joint detection for TD-SCDMA systems: SNR estimation and active codes detection

This paper focuses on specific signal processing functions which are part of downlink joint detection (JD) for time division synchronous CDMA (TD-SCDMA) systems. We propose new algorithms to estimate the signal-to-noise ratio and detect the active channelization codes in JD receiver. The performance of these algorithms are evaluated by computer simulations for the zero-forcing JD, and the minimum mean- square error joint detectors. Simulation results indicate that, compared to zero-forcing JD, the minimum mean-square error joint detector exhibits robust performance in the presence of large channel estimation errors and active channelization codes mismatch.

Digital Compensation of Tx/Rx I/Q Imbalance in TD-SCDMA Systems

TD-SCDMA (Time Division- Synchronous CDMA) systems show performance degradation due to I/Q imbalance resulting from direct-conversion transmitters and receivers. In overall system analysis, it is important to consider both transmitter and receiver I/Q imbalances to account for low cost base stations (BSs) such as femtocells. Two approaches are considered in this paper. The first one is a purely time-domain approach based on widely linear minimum mean square error estimation (WL-MMSE). The second one is a frequency-domain approach with reduced computational complexity. Simulation studies are performed and comparison results presented.