In this paper, the performance of limited feedback precoded spatial multiplexing multiple-input multiple-output orthogonal frequency division multiplexing (MIMO - OFDM) systems is investigated in time varying fading channels. Most studies into limited feedback precoded (MIMO - OFDM) systems are based on the notion of time invariant channels throughout transmission. Therefore, the precoding matrix for each subcarrier can be designed at the receiver in terms of the current channel state, fed back to the transmitter, and used for the subsequent block of data symbols. However, in time varying channels, the feedback information becomes outdated, which results in significant system performance degradation. To mitigate this system performance degradation caused by outdated information due to a delay in the feedback channel, this paper considers a more practical system, where the channel varies from one block

Conventional precoded spatial multiplexing multiple-input multiple-output (MIMO) systems using limited feedback are mainly based on the notion of time invariant channels throughout transmission. Consequently, the precoding matrix can be found during the training symbols and used over the subsequent data symbols. In this study, the authors consider a more practical system where the channel varies from one block of symbols to another. In such a scenario, the precoding matrix designed at the receiver based on the previous training symbols becomes outdated, which results in significant system performance degradation. In order to avoid this problem and reduce performance degradation, the authors propose the use of a Kalman filter linear predictor at the receiver to provide the transmitter with the precoding matrix for the next block of symbols. The performance of this method is assessed using computer …

In this paper a low complexity MIMO MC-CDMA receiver is proposed. We investigate the receiver performance and complexity in the case of despreading multicarrier code division multiple access signals (MC-CDMA) prior to V-BLAST detection in multiple input multiple output systems (MIMO). The proposed structure shows that for iterative detection, despreading before detection (DBD) reduces the effect of multiple access interference (MAI), and the reported results demonstrate improved bit error rate (BER) performance and user capacity of the system over despreading after detection (DAD). Furthermore, DBD results in reduced system complexity. The performance of both detectors is evaluated using computer simulations for a frequency selective slow Rayleigh fading channel.