Techniques for channel estimation in millimeter wave communication systems

1. A method for performing channel estimation in a millimeter wave wireless communication system, comprising:

receiving complementary sequences at a receiver of the millimeter wave wireless communication system, wherein the received complementary sequences are Golay complementary sequences generated at a first sampling rate;

producing special complementary sequences from the received complementary sequences, wherein the special complementary sequences Golay complementary sequences;

cross-correlating the special complementary sequences with an input signal related to the received complementary sequences, wherein the cross-correlation is performed at a second sampling rate and the second sampling rate is higher than the first sampling rate, wherein the cross-correlation is performed by a Golay correlator operating at the second sampling rate, wherein the Golay correlator includes log2(N) operation where N is a length of the received complementary sequences; and

analyzing the result of the cross-correlation to estimate at least characteristics of a channel between the receiver and a transmitter of the millimeter wave wireless communication system.

2. The method of claim 1 , wherein producing the special complementary sequences includes:

using a number samples of the received complementary sequences equals to a length of the received complementary sequences divided by a ratio, when the ratio between the second sampling rate and the first sampling rate is a power of two.

3. The method of claim 2 , wherein the cross-correlation is performed by the Golay correlator that includes:

a first number of delay blocks respective of a last first number of delay values of the received complementary sequences, each of the delay blocks waits until a number of samples equals to a respective delay value divided by the ratio are obtained;

a first number of multipliers for applying a last first number of weight values of the received complementary sequences;

a first number of adders; and

a first number of subtractors, wherein the first number equals to log2(N) minus the ratio between the second sampling rate and the first sampling rate.

4. The method of claim 1 , wherein producing the special complementary sequences includes:

producing even complementary sequences including only even samples of the received complementary sequences; and

producing odd complementary sequences including only odd samples of the received complementary sequences, wherein the even complementary sequences and odd complementary sequences are produced when a ratio between the second sampling rate and the first sampling rate is 3/2.

5. The method of claim 4 , wherein the cross-correlation is performed by the Golay correlator that includes:

a first correlator for cross-correlating the even complementary sequences; and

a second correlator for cross-correlating the odd complementary sequences.

6. The method of claim 5 , wherein the first correlator includes:

a K- 1 delay blocks respective of last K- 1 delay values of the received complementary sequences, each of the delay blocks waits until a number of samples equals to half of a respective delay value are obtained;

a K- 1 multipliers for applying last K- 1 of weight values of the received complementary sequences;

an even multiplier connected to a first delay block of the K- 1 delay blocks for multiplying the input signal by a Weven value;

a K- 1 adders; and

a K- 1 subtractors, wherein K equals to a log 2 value of a length of one of the received complementary sequences.

7. The method of claim 5 , where the second correlator includes:

a K- 1 delay blocks respective of last K- 1 delay values of the received complementary sequences, each of the delay blocks waits until a number of samples equals to half of a respective delay value are obtained;

a K- 1 multipliers for applying last K- 1 of weight values of the received complementary sequences;

an odd multiplier that multiplies the input and provides the multiplication results first delay block of the K- 1 delay blocks, wherein the input is multiplied by a first weight value of the received complementary sequences;

a K- 1 number of adders; and

a K- 1 subtractors.

8. The method of claim 6 , wherein a value of the Weven equals to −1.

9. The method of claim 1 , wherein the receiver and transmitter of the millimeter wave wireless communication system communicate using an IEEE 802.11ad protocol.

10. A non-transitory computer-readable medium having stored thereon computer executable code that when executed by a processor performs the method of claim 1 .

11. An apparatus operable in a receiver of a millimeter wave wireless communication system and configured to perform channel estimation, comprising:

a radio frequency circuitry for receiving millimeter wave signals including Golay complementary sequences, wherein the received complementary sequences are generated at a first sampling rate;

a processor for producing special Golay complementary sequences from the received complementary sequences; and

a Golay correlator for cross-correlating special Golay complementary sequences with an input signal related to the received Golay complementary sequences, wherein the cross-correlation is performed at a second sampling rate and the second sampling rate is higher than the first sampling rate, and wherein the Golay correlator includes log2(N) operations where N is a length of one of the special Golay complementary sequences.

12. The apparatus of claim 11 , wherein the Golay correlator includes:

a first number of delay blocks respective of a last first number of delay values of the received complementary sequences, wherein each of the delay blocks waits until a number of samples equals to respective delay value divided by a ratio between the second sampling rate and the first sampling rate are obtained;

a first number of multipliers for applying a last first number of weight values of the received complementary sequences;

a first number of adders; and

a first number of subtractors, wherein the first number equals to log2(N) minus the ratio.

13. The apparatus of claim 11 , wherein the processor is further configured to produce even complementary sequences including only even samples of the received complementary sequences and odd complementary sequences including only odd samples of the received complementary sequences, wherein the even complementary sequences and the odd complementary sequences are produced when a ratio between the second sampling rate and the first sampling rate is 3/2.

14. The apparatus of claim 13 , wherein the Golay correlator comprises:

a first correlator for cross-correlating the even complementary sequences with an input signal; and

a second correlator for cross-correlating the odd complementary sequences with an input signal.

15. The apparatus of claim 14 , wherein the first correlator includes:

a K- 1 delay blocks respective of last K- 1 delay values of the received complementary sequences, wherein each of the delay blocks waits until a number of samples equals to half of a respective delay value are obtained;

a K- 1 multipliers for applying last K- 1 of weight values of the received complementary sequences;

an even multiplier connected to a first delay block of the K- 1 delay blocks for multiplying an input sample value with a Weven value;

a K- 1 number of adders; and

a K- 1 subtractors, wherein K equals to a log 2 value of a length of the received complementary sequences.

16. The apparatus of claim 14 , wherein the second correlator includes:

a K- 1 delay blocks respective of last K- 1 delay values of the received complementary sequences, wherein each of the delay blocks waits until a number of samples equals to half of a respective delay value are obtained;

a K- 1 multipliers for applying last K- 1 of weight values of the received complementary sequences;

an odd multiplier that multiplies the input and provides the multiplication results first delay block of the K- 1 delay blocks, wherein the input is multiplied by a first weight value of the received complementary sequences;

a K- 1 number of adders; and

a K- 1 subtractors, wherein K equals to a log 2 value of a length of the received complementary sequences.

17. The apparatus of claim 11 , wherein the receiver communicates with a transmitter of the millimeter wave wireless communication system using an IEEE 802.11ad protocol.