This paper compares the performance and complexity of various MIMO receiver structures for 802.11n WLAN systems, including linear approaches such as MMSE and ZF, and iterative detection and decoding using list sphere decoding. Optimal beam steering with the low-complexity MMSE receiver is shown to outperform the computationally-expensive list sphere decoder receiver with an uninformed transmitter

A method for predicting packet error rates in MIMO-OFDM WLAN systems is presented. The method is based on using post-detection SNRs as an abstraction of the physical layer, and is motivated by the need for a simple and efficient way of modelling the physical layer in system level simulation scenarios involving multiple stations. The physical layer abstraction is sufficient for generating error processes in the system simulations that accurately reflect the interaction between the MIMO-OFDM physical layer and the underlying wireless channel. We validate the abstract model by comparing packet error rates predicted by the model with packet error rates obtained through full link simulations for two different approaches to MIMO processing, referred to as spatial spreading and eigenvector steering.

This paper presents two transmission techniques for MIMO OFDM communication, referred to as spatial spreading and eigenvector steering. Spatial spreading is used when the transmitting station is not presumed to have sufficient channel state information to compute optimum steering vectors. This situation may occur for a variety of reasons, including poor or aged channel estimates or lack of calibration between the transmit and receive antenna chains. Eigenvector steering is used in cases where the transmitting station has sufficient information about the channel to compute optimum transmit steering vectors. Simulation results showing throughput and range achieved by the two transmission strategies are provided.

In this paper, we analyze the performance of various receive antenna diversity schemes for use in combination with transmit diversity on the downlink of wideband code-division multiple-access third-generation systems. We consider open loop and closed loop versions of both maximal ratio combining and selection diversity, and study the impact of channel correlation on the performance of these schemes. We also present an analysis of the asymptotic performance of coded systems. The analytical results are compared with simulation results obtained in typical channels.

We evaluate and compare several data detection schemes used in GSM systems. In particular, we compare the performance of decision feedback equalization (DFE) and nonlinear data directed estimation (NDDE) to that of maximum likelihood sequence estimation (MLSE). Establishing the performance of the basic NDDE detector is a first step in investigating the applicability of block transmission techniques to GSM systems. Our simulation results, obtained both for fading multipath channels and adjacent- and co-channel interference scenarios, suggest that the NDDE offers certain performance advantages over the DFE, and the performance of both detectors is comparable to that of the MLSE for the SNR region of interest in practical systems. Thus, they both represent viable alternatives to the MLSE detector.

We consider wireless communication systems that employ multiple transmitting and receiving antennas to achieve spatial diversity and to increase the data rate through fading channels. In particular, we focus on a system with N transmitting antennas and M receiving antennas. We consider the design and performance evaluation of several detection algorithms for recovering the original data from the received signals on the M antennas. These algorithms include the optimum maximum likelihood detector and suboptimal reduced-complexity detectors such as the MMSE detector and a detector based on maximal ratio combining. We also consider coded systems.

In this paper, we evaluate low complexity detectors for use in the GSM system. In particular, we compare the performance of decision feedback equalization (DFE) and nonlinear data directed estimation (NDDE) to that of the optimal maximum likelihood sequence estimation (MLSE). Establishing the performance of the basic NDDE detector is a first step in investigating the applicability of block transmission techniques to the GSM system. Simulation results, obtained both for fading multipath channels and adjacent- and co-channel interference scenarios, show that the NDDE performs just as well as the DFE, and the performance of both low complexity detectors is comparable to that of the MLSE for the SNR region of interest in practical systems.