Use of correlation combination to achieve channel detection
Wireless mobile devices are disclosed. A receiver to receive a coded signal having a code applied to the received coded signal includes a lower rate code comprising at least two code sequences of a higher rate code. One or more correlators are coupled with the receiver to correlate the received coded signal with the higher rate code to provide a higher rate code correlation result, to correlate the higher rate code correlation results with a first lower rate code to provide a first lower rate code correlation result, and to correlate the higher rate code correlation results with a second lower rate code to provide a second lower rate code correlation result. A comparator is coupled with the one or more correlators to compare the first lower rate code correlation result to the second lower rate code correlation result to determine presence of a signal indication.
1. A method for use in wireless communications, the method comprising:
receiving a message in a time slot with a receiver of a mobile wireless device, receiving a coded signal wherein a code applied to the received coded signal includes a lower rate code comprising at least two code sequences of a higher rate code;
decoding the received message by correlating the received coded signal at the receiver with the higher rate code to provide a higher rate code correlation result, correlating the higher rate code correlation results with a first lower rate code to provide a first lower rate code correlation result, correlating the higher rate code correlation results with a second lower rate code to provide a second lower rate code correlation result, and comparing the first lower rate code correlation result to the second lower rate code correlation result to determine the presence of a signal indication; and
performing synchronization with an access unit based on the decoded received message.
2. A mobile wireless device comprising:
a receiver to receive a coded signal, wherein a code applied to the received coded signal includes a lower rate code comprising at least two code sequences of a higher rate code;
one or more correlators coupled with the receiver to correlate the received coded signal with the higher rate code to provide a higher rate code correlation result, to correlate the higher rate code correlation results with a first lower rate code to provide a first lower rate code correlation result, and to correlate the higher rate code correlation results with a second lower rate code to provide a second lower rate code correlation result; and
a comparator coupled with the one or more correlators to compare the first lower rate code correlation result to the second lower rate code correlation result to determine presence of a signal indication.
3. The mobile wireless device of claim 2 wherein the received coded signal is received periodically.
4. The mobile wireless device of claim 2 wherein the lower rate codes are orthogonal to each other.
5. The mobile wireless device of claim 2 wherein the lower rate codes are Walsh codes.
6. The mobile wireless device of claim 2 wherein the lower rate codes are Gutleber codes.
7. The mobile wireless device of claim 2 wherein the lower rate codes are maximum length sequences.
8. The mobile wireless device of claim 2 wherein the lower rate codes are PN-sequences.
9. The mobile wireless device of claim 2 wherein the higher rate code is 32 chips in length and the lower rate codes are 128 chips in length.
10. The mobile wireless device of claim 2 wherein the lower rate codes are used for timing signals.
11. A mobile wireless device comprising:
a receiver to receive a coded signal wherein a code applied to the received coded signal includes a lower rate code comprising at least two code sequences of a higher rate code;
a demodulator coupled with the receiver, the demodulator to demodulate the received coded signal into in-phase and quadrature components;
one or more correlators coupled with the demodulator, the one or more correlators to correlate the in-phase and quadrature components with the higher rate code to provide higher rate code correlation results, to correlate higher rate code correlation results with a first lower rate code to provide a first lower rate code correlation result, and to correlate higher rate code correlation results with a second lower rate code to provide a second lower rate code correlation result;
a comparator coupled with the one or more correlators to compare the first lower rate correlation result to the second lower rate code correlation result to determine the presence of a signal indication.
12. The mobile wireless device of claim 11 wherein the N lower rate codes are selected based on a priori system information.
13. The mobile wireless device of claim 11 wherein the received coded signal is received periodically.
14. The mobile wireless device of claim 11 wherein the lower rate codes are orthogonal to each other.
15. The mobile wireless device of claim 11 wherein the lower rate codes are Walsh codes.
16. The mobile wireless device of claim 11 wherein the lower rate codes are Gutleber codes.
17. The mobile wireless device of claim 11 wherein the lower rate codes are maximum length sequences.
18. The mobile wireless device of claim 11 wherein the lower rate codes are PN-sequences.
19. The mobile wireless device as in claim 11 wherein the lower codes are nested codes comprising at least two code sequences of a base code and N nested lower rate codes are selected from of a set of M possible nested codes.