Space-Time Block Coding for Uplink Single-Carrier CDMA with Joint Detection in the Frequency Domain

Abstract

Abstract-Single-carrier code-division multiple access (SC-CDMA), also named cyclic-prefix CDMA in the literature, is a promising air interface for the uplink of the 4G cellular wireless communication systems. It enables the high capacity intrinsically offered by CDMA by making the equalization of the multipath channels and the mitigation of the resulting interference possible at a low complexity. This paper proposes a new air interface that combines SC-CDMA with space-time block coding (STBC) across multiple transmit antennas in order to make the link more robust. Contrary to existing air interfaces that perform the STBC at the chip level, making them only applicable to the downlink, the STBC is performed at the symbol level, making it also applicable to the uplink. In order to optimally detect the different antenna and user signals, a linear joint detector optimized according to the minimum mean square error (MMSE) criterion is designed. By exploiting the cyclic properties of the channel matrices, the complexity of the joint detector is significantly reduced. Furthermore, it is shown analytically that the inter-antenna interference is canceled out at the output of the first stage of the linear MMSE joint detector, consisting of a matched filter. By space-time coding the signal through two antennas at each transmit mobile terminal, a significant gain in signal-to-noise-ratio can be achieved. However, the spatial diversity gain of the proposed system is limited by the multi-user interference (MUI), that is increasing with the user load. Higher complexity non-linear receivers are needed to better compensate the MUI and still benefit from the spatial diversity at high user loads.

Multiple user channel capacity analysis of code-division multiple access system based on space-time block coding

“…:rBCYSTBC( i ) (10) , MMSE-BLE combined detector includes two functions: one is to reduce the influence of white noise, to matched ftltering of the received signal vector. Another is to eliminate residual interference of sym boIs, interference of users, and interference of antennas.…”

MMSE-BLE Algorithm of Single-Carrier Multi-User Channel Capacity

“…Decoding with joint detection algorithm MMSE-BLE [9,[12][13], follow least mean square criterion, seeking a detection signal ( )…”

“…Multiple access system will be disturbed by inter-symbol interference and multiple access interference. MMSE-BLE algorithm is a joint detection algorithm by using the time domain equilibrium technology to eliminate ISI and MAI at maximal degree, with the optimal linear Wiener filter and the introduction of the signal-correlation covariance matrix to resist noise, the performance of it is better than ZF-BE in TDD standard [7][8][9][10][11].…”