Multislot estimation of fast-varying space-time communication channels

Abstract

In mobile communications, coherent detection requires the estimate of an increasing number of channel parameters due to the promising performance of systems that deploy multiple antennas. However, the estimate of space-time channels requires a number of training symbols that grows with the number of unknowns. To overcome this problem, we propose a subspace-based estimation method that exploits the different varying rates in the structure of the space-time channel for moving terminals. Since the channel has some fast-varying (faded amplitudes of the paths) and slowly varying (delays and directions of arrival) features, the multislot (MS) estimate is composed of two terms: the slowly varying spatial and temporal bases estimated from L consecutive slots and the fast-varying amplitudes estimated on a slot-by-slot basis. Performance analysis and simulations confirm the expected benefits of the multislot approach and demonstrate that for large L, the mean square error (MSE) on the channel estimate depends only on the number of fast-varying parameters

Adaptive Array Processing for Time-Varying Interference Mitigation in IEEE 802.16 Systems

“…It can be seen that, even though the MLS estimate is more convenient than MST in terms of MSE h ( ), its error on the decision variable MSE x,2 ( ) is significantly larger than MST. We can thus conclude that MST is better suited to be used for MVDR beamforming (6).…”

“…Given the signal received on the preamble (s = 0) of any burst, the conventional approach for the estimation of H( , 0) is the Least Squares (LS) technique [6]:…”

“…The temporal component is still constant over the whole frame. The optimal estimate for such a channel structure, characterized by a non-stationary spatial component and a constant temporal component, can be derived following the maximum likelihood approach [6]. We refer to the resulting estimate as multi-preamble space-time estimate (MST) given by…”

Adaptive Transmission with Partial Channel Information in Spatially Correlated MIMO Channels

“…Since the correlation can be assumed unchanged during the time interval much longer than the duration of fading [6], it can be informed to the transmitter without significant increase of feedback signaling overhead. However, the use of channel correlation information is not sufficient for the maximization of the capacity [7], resulting in a large capacity loss compared to the use of full channel information especially when the channel is partially correlated.…”

Reduced-rank channel estimation for time-slotted mobile communication systems

“…On the other hand, unstructured approaches translate the stationarity of angles/delays into the invariance of the spatial/temporal subspaces spanned by the corresponding channel signatures. In particular, subspace methods have been proposed to take advantage of the invariance of either the spatial [18], [19] or the temporal [19] subspace of the channel matrix. All these unstructured methods are derived in this paper in a common framework as an extension of the RR estimate to multiple training blocks.…”