Adaptive Minimum Mean-squared Error Receiver Research Articles

Convolutionally Coded Adaptive Space-Time MMSE Receiver for W-CDMA Systems in Multipath Channels

In this paper, we consider the use of convolutionally coded adaptive space-time minimum mean-square error (MMSE) receiver for wideband code division multiple access (W-CDMA) systems in multipath channels. In the adaptive space-time MMSE receiver, antenna array processing is combined with MMSE multiuser detection (MUD). Simulations are carried out to evaluate the performance in the directional multi path quasi-static Rayleigh fading channels. Simulation results show that substantial performance improvement may be obtained by using convolutional codes jointly with the adaptive space-time MMSE receiver. Only requirement to implement the receiver is a training sequence and a priori knowledge of the users’ timing for only the strongest path.

Adaptive MMSE receiver with beamforming for DS/CDMA systems

The minimum mean-squared error (MMSE) receiver is a linear filter which can suppress multiple access interference (MAI) effectively in direct-sequence code-division multiple-access (CDMA) communications. An antenna array is also an efficient scheme for suppressing MAI and improving the system performance. In this letter, we consider an adaptive MMSE receiver in conjunction with beamforming in CDMA systems employing an antenna array. The proposed structure is featured as a low complexity receiver, which adapts the MMSE filter coefficients and the beamforming weights simultaneously. However, it does require the channel state information and the direction of arrival (DOA) of the desired user signal. As a result, we propose two adaptation methods to perform joint channel estimation and signal detection without any training sequence. It is demonstrated that the two proposed methods achieve similar bit-error-rate performance. More importantly, their performance degradation compared with the case with perfect channel information is small.

Computationally efficient adaptive MMSE receiver for synchronous MC-CDMA communication systems

An adaptive receiver is proposed for multicarrier code-division multiple-access (MC-CDMA) systems to suppress both intersymbol interference and multiple access interference. The proposed minimum mean squared error (MMSE)-based receiver eliminates the need of the discrete or fast Fourier transform operation without any performance loss in the communications channels considered.

Partial zero-forcing adaptive MMSE receiver for DS-CDMA uplink in multicell environments

Adaptive multi-user detection techniques for interference suppression in direct-sequence code division multiple access (DS-CDMA) systems have gained much attention since they do not require any information on interfering users. In the uplink of DS-CDMA systems, however, the base station receiver typically knows the spreading waveforms of the users within its cell but does not know those of the users in other cells. We propose a partial zero-forcing adaptive minimum mean squared error (MMSE) receiver for the DS-CDMA uplink utilizing the spreading waveforms known at the base station as well as training data. The proposed receiver first removes the intracell interference using a linear filter based on the knowledge of the spreading waveforms of the interfering users within the cell. Then the intercell interference remaining in the output of the linear filter is mitigated by adaptive MMSE detection. To speed up the convergence of the adaptive filter weights without loss of the steady-state performance, we develop a modified least mean square (LMS) algorithm based on the canonical representation of the filter weights. It is shown through analysis and simulation results that the proposed receiver improves the convergence speed and the steady-state performance.

Symbol-level Rake MMSE receiver for asynchronous DS/CDMA systems in multipath fading channels

A new nonlinear adaptive minimum mean squared error (MMSE) receiver performing a successful cancellation of multiple access interference in multipath fading channels is proposed. It is observed that the proposed receiver could achieve a significant performance gain over any currently used adaptive MMSE receivers, at the cost of a relatively small increase in complexity and modification of the conventional DS/CDMA system.

Adaptive space-time reduced-length MMSE receiver for interference suppression in DS/CDMA

The authors present an adaptive space-time reduced-length minimum mean-squared error (MMSE) receiver to suppress co-channel interference in the near-far environment for an asynchronous direct-sequence code-division multiple-access (DS/CDMA) system. Simulation results show that better bit-error rate and faster and more stable convergence are achieved over the existing full- and reduced-length MMSE receivers.