OFDM channel estimate interpolator which calculates virtual replacement pilot at discontinuities in scattered pilot pattern

摘要

Orthogonal frequency division multiplex (OFDM) systems typically use scattered pilot training symbols for channel response estimation, from which channel responses of data sub-carriers are interpolated. These are typically arranged in regular repeating patterns, however there can be discontinuities in these patterns (eg. at a frame boundary, see Figs. 3,5). The interpolator comprises an FIR filter 214.1 which operates on the expected 212 and received 208 received symbols. The filter requires the regular repeating pattern for correct operation. Where a break in the pattern causes an irregularity the controller 320.1 causes the re-sample generator 324.1 to create virtual pilots to maintain the pattern. The new pilot sample location 466 is kept and the older samples 464 are discarded and replaced with calculated pilot samples 470 in the correct pattern position (see Fig. 10d). The invention may be applied in DVB-T2 systems.