Synchronization method for symbol boundary detection in UWB-OFDM
View Patent ↗A method is presented for packet detection and symbol boundary location using a two-step sign correlation procedure. When the correlation crosses a threshold, a packet detection signal is generated to initiate processing of downstream blocks, and a symbol boundary location signal is generated for use in aligning data during processing.
1. A method for symbol boundary detection in UWB-OFDM, comprising:
determining a sign of a preamble input comprising multi-level samples;
correlating the sign of the preamble input with the sign of a first reference pattern to produce correlated values;
comparing the correlated values with a first threshold to create an intermediate correlation stream;
correlating the intermediate correlation stream with a second reference pattern to form an overall correlation;
finding a position where the overall correlation crosses a second threshold; and
finding a second position where the overall correlation crosses the second threshold within approximately 1 symbol from the first threshold crossing.
2. The method of claim 1 , wherein the input comprises in phase (I) and quadrature (Q) channels.
3. The method of claim 1 , wherein the second threshold is adapted based on summing and scaling the correlation values from a previous packet.
4. The method. of claim 1 , wherein the first reference pattern includes an 8-value subpattern.
5. The method of claim 1 , wherein the second reference pattern includes a 16-value pattern of subpatterns.
6. The method of claim 1 , further comprising finding a variable number of threshold crossings in the overall correlation separated from the first threshold crossing by approximately an integer number of symbols.
7. The method of claim 1 , further comprising aligning data based on the found position.
8. The method of claim 1 , further comprising processing and decoding data.
9. The method of claim 1 , further comprising squaring the overall correlation and finding a position where the squared correlation crosses the second threshold.
10. A system for symbol boundary detection in UWB-OFDM, comprising:
means for determining a sign of a preamble input comprising multi-level samples;
means for correlating the sign of the preamble input with the sign of a first reference pattern to produce correlated values;
means for comparing the correlated values with a first threshold to create an intermediate correlation stream;
means for correlating the intermediate correlation stream with a second reference pattern to form an overall correlation;
means for finding a position where the overall correlation crosses a second threshold; and
means for finding a second position where the overall correlation crosses the second threshold within approximately 1 symbol from the first threshold crossing.
11. A system for symbol boundary detection in UWB-OFDM, comprising:
a sign determiner capable of determining the sign of a preamble input comprising multi-level samples;
a first correlation block, coupled to the sign determiner, capable of correlating the sign of the preamble input with the sign of a first reference pattern to produce correlated values;
a comparator, coupled to the first correlation block, capable of comparing the correlated values with a first threshold to create an intermediate correlation stream;
a second correlation block, coupled to the comparator, capable of correlating the intermediate correlation stream with a second reference pattern to form an overall correlation;
a threshold crossing determiner, coupled to the second correlation block, capable of finding a position where the overall correlation crosses a second threshold; and
a second threshold crossing determiner capable of finding a second position where the overall correlation crosses the second threshold within approximately 1 symbol from the first threshold crossing.
12. The system of claim 11 , wherein the input comprises in phase (I) and quadrature (Q) channels.
13. The system of claim 11 , wherein the second threshold is adapted based on summing and scaling the correlation values from a previous packet.
14. The system of claim 11 , wherein the first reference pattern includes an 8-value subp att em.
15. The system of claim 11 , wherein the second reference pattern includes a 16-value pattern of subpatterns.
16. The system of claim 11 , wherein the second threshold crossing determiner is further capable of finding a variable number of threshold crossings in the overall correlation separated from the first threshold crossing by approximately an integer number of symbols.
17. The system of claim 11 , further comprising circuitry capable of aligning data based on the found position.
18. The system of claim 11 , further comprising circuitry capable of processing and decoding data.
19. The system of claim 11 , further comprising a squaring device, coupled to the second correlation block, capable of squaring the output of the second correlation block; and
wherein the threshold crossing determiner is coupled to the squaring device and capable of finding a position where the squared correlation crosses the second threshold.