Block interpolation filter structure using lookup table
The present invention based on the LUT enables to perform a filtering at a low speed on a place where a high-speed process is necessary. Particularly, the LUT structure having a block structure is advantageous for filtering at a low speed, and for decreasing memory usage. The filter structure proposed by the present invention provides the equivalent performances to those of the traditional ones, yet conducts the filtering on an interpolation process requiring a high-speed process previously at a low speed and at a low power instead. Moreover, compared to the traditional LUT based filter, the present invention provides a new structure with a decreased memory demand. In short, the present invention provides a new filter structure that enables to implement an interpolation filter, a high-speed processor of a sending end in a wireless telecommunication system, with a low complexity and a low power consumption.
1. An N-tap block interpolation filter with an interpolation rate M, comprising:
an N/M sized input buffer;
N/M look up table (LUT) subfilters having a filter coefficient equal to the interpolation rate M for outputting a pre-saved filtering result by conducting an indexing on an input stream wherein M is a non-zero integer and N is an integer multiple of M;
M adders for vector addition of each filtering result output by the subfilters; and
M parallel-serial buffers for buffering each result from the M adders.
2. The N-tap block interpolation filter according to claim 1 , wherein the input buffer is a transitional buffer for buffering N/M samples.
3. An N-tap block interpolation filter with an interpolation rate M, comprising:
an N/M sized input buffer;
a 2×1 multiplexer for multiplexing outputs from the input buffer;
N/2M look up table (LUT) subfilters having a filter coefficient equal to the interpolation rate M for outputting a pre-saved filtering result by conducting an indexing on an input stream wherein M is a non-zero integer and N is an integer multiple of 2M;
M adders for vector addition of each filtering result output by the subfilters; and
M parallel-serial buffers for buffering each result from the M adders.
4. The N-tap block interpolation filter according to claim 3 , wherein the filtering result is outputted by accessing N/2M LUT subfilters two times per sample input from the input buffer through the multiplexer.
5. An N-tap block interpolation filter with an interpolation rate M, comprising:
an N/M sized input buffer;
a 2×1 multiplexer for multiplexing outputs from the input buffer;
at least one pair of LUT subfilters for receiving m inputs from the multiplexer, for conducting an indexing over an input stream wherein M is a non-zero integer, N is an integer multiple of M and m is an integer, and for outputting a filtering result that includes a pre-saved addition operation;
M adders for vector addition of each filtering result output by the subfilters; and
M parallel-serial buffers for buffering each result from the M adders.