Channel estimation complexity reduction using caching

In this paper, the caching concept is applied to the calculation of channel information for equalisation in a wireless communication system. The concept has been evaluated using a real-time time-reversal space-time block coding implementation, and in particular is applied to the complex time varying channel estimates captured from this system. The evaluation was performed with channels under three distance conditions in an indoor, relatively scattering office environment at a carrier frequency of 2.45 GHz. Since the time reversal system employed two transmitters spaced 50 cm apart and a single receiver, there are two complex channels available for each capture instant. The data rate is 2 Mbits per second and operates at an oversampling ratio of 5:1. Various replacement policies are tested within the caching system for a range of cache sizes and the mean-squared error matching criteria,to produce results that explores the effectiveness of the system under the evaluation conditions. Results indicate that the method is particularly applicable if the decoding process complexity is to be minimised for reasons of average power consumption, such as those in the battery powered systems, or where non real-time decoder processing is acceptable, such as in IP transport systems.