Indirect Spatio-Temporal Equalization and Adaptive Interference Cancellation for Multipath Environments in Mobile Radio Applications

Erik Lindskog

IEEE/IEE Workshop on Signal Processing Methods in Multipath Environments, Glasgow, UK, April 20-21 1995, pp 115-124. © 1995 IEEE,IEE.

Abstract:

Combined spatial and temporal equalization with a multi-antenna decision feedback equalizer is considered for a TDMA mobile radio system. Unless the time frame allocation is synchronized for all surrounding base stations, the co-channel interferers may start to interfere at arbitrary time instances during a base station reception. A co-channel interferer may thus be present during the data sequence of the time frame, while it is not present during the training sequence.

In order to handle this situation, adaptation to the changing interference environment is introduced.

The covariance matrix estimates needed for tuning the equalizer parameters are partitioned into a signal part and a noise plus interference part. The signal part is derived from identified signal channels, while the noise plus interference part is constructed by only considering the spatial correlations of the residuals from the identification procedure.

Two versions of the equalizer are considered. The first algorithm is adapted by updating the noise plus interference part of the covariance matrix estimate, and it then re-tunes the equalizer at appropriate intervals.

The second algorithm performs the adaptation by tuning a number of separate beamformers. This adaptation requires considerably less computations, at the price of a potential performance degradation. For the investigated scenario, the performance degradation is however minor.

Related publications:

Licentiate Thesis by E Lindskog 1995, which includes the paper.
Conference paper in IEEE VTC'95, which investigates related algorithms.

Source:

Pdf, 455K.