Channel prediction in multiple antenna systems

Techniques to predict the channel transfer functions into time direction and into frequency direction in multiple antenna systems are investigated in this paper. Having full channel state information at the receiver side and at the transmitter side in a mobile radio system is crucial for many sophisticated transmission techniques. Unfortunately, only channel state information at the receiver side can be estimated based on the transmission of a priori known training signals. This estimated channel state information cannot be directly reused as channel state information at the transmitter. Due to the use of different frequency bands in frequency division duplex systems, the estimated receiver side channel state information differs significantly from the transmitter side channel state information. Furthermore, due to the delay between estimating the receiver side channel state information and using this information at the transmitter side, the estimated receiver side channel state information can often not be directly reused in time division duplex systems. Thus, a prediction is appropriated. In time division duplex systems only a prediction into time direction is relevant. In frequency division duplex systems a prediction into frequency direction and potentially also a prediction into time direction are relevant. This paper shows different techniques to perform the prediction of the estimated receiver side channel state information to achieve transmitter side channel state information in multiple antenna systems. Channel measurements were conducted in a typical indoor scenario in order to evaluate the performance of the proposed prediction techniques.