Granted Patent B2

US 7,333,456 · App. 11/192,343 · Granted Feb 19, 2008

Abstract

Claims (39)

1. A method for transmitting training information in a block transmission system, the block transmission system being a frequency reuse system, the method comprising the steps of;

a. transmitting a first information bearing unit, the first information bearing unit being transmitted by at least one transmit antenna; and

b. transmitting a second information bearing unit, the second information bearing unit being transmitted by the at least one transmit antenna, the second information bearing unit being the first information bearing unit shifted by a frequency offset, wherein the combination of the first information bearing unit and the second information bearing unit is substantially periodic, the combination of the first information bearing unit and the second information bearing unit being one of preamble, midamble, or postamble;

whereby, the frequency offset increases the pilot density of transmission from a transmit antenna.

2. The method of claim 1 , whereby each transmit antenna is trained simultaneously.

3. The method of claim 1 , wherein the first information bearing unit comprises a predetermined identifier and a cell identifier.

4. The method of claim 1 , wherein the frequency offset is an integer frequency offset.

5. The method of claim 4 , wherein the integer frequency offset is equal to three sub-carriers if the number of transmit antennas is at most two and if the number of sectors in a cell is equal to three, wherein the number of transmit antennas is determined at a receiver based on a predetermined identifier.

6. The method of claim 3 , wherein the predetermined identifier and the cell identifier are transmitted simultaneously by a first transmit antenna, if the number of transmit antennas is equal to one.

7. The method of claim 3 , wherein the predetermined identifier is transmitted by a first transmit antenna and the cell identifier is transmitted by a second transmit antenna, if the number of transmit antennas is equal to two.

8. The method of claim 4 , wherein the integer frequency offset is equal to six sub-carriers if the number of transmit antennas is three or four and if the number of sectors in a cell is equal to three, wherein the number of transmit antennas is determined at a receiver based on a predetermined identifier.

9. The method of claim 3 , wherein the predetermined identifier is transmitted by a first transmit antenna and the cell identifier is transmitted by a second transmit antenna, if the number of transmit antennas is equal to two.

10. The method of claim 8 , wherein the first information bearing unit further comprises at least one training sequence, the at least one training sequence training at least one transmit antenna.

11. The method of claim 10 , wherein a predetermined identifier is transmitted by a first transmit antenna, a cell identifier is transmitted by a second transmit antenna, and the training sequence is transmitted by a third transmit antenna if the number of transmit antennas is equal to three.

12. The method of claim 1 , wherein a pilot is transmitted on at least one unused-sub-carrier, wherein an unused-sub-carrier is a sub-carrier allocated to a sector and no transmission occurs on the unused-sub-carrier.

13. The method of claim 1 , wherein a combination of the first information bearing unit and the second information bearing unit transmitted in a particular sector is substantially similar to a combination of the first information bearing unit and the second information bearing unit transmitted in a sector that has a predefined number of transmit antennas, wherein the number of transmit antennas in the particular sector is less than the predefined number of transmit antennas, wherein the predefined number of transmit antennas is equal to maximum number of transmit antennas per sector of the block transmission system.

14. A method for enabling channel estimation and synchronization of a receiver in a block transmission system, the block transmission system being a frequency reuse system, the method comprising the steps of;

a. transmitting a first information bearing unit, the first information bearing unit being transmitted by at least one transmit antenna, the first information bearing unit comprising a predetermined identifier and a cell identifier;

b. transmitting a second information bearing unit, the second information bearing unit being transmitted by the at least one transmit antenna, the second information bearing unit being the first information bearing unit shifted by a frequency offset, wherein the combination of the first information bearing unit and the second information bearing unit is substantially periodic;

c. obtaining at least one of coarse timing offset estimate and fractional frequency offset estimate by using the periodicity of the combination of the first information bearing unit and the second information bearing unit;

d. identifying the cell identifier based on the obtained at least one of coarse timing offset estimate and fractional frequency offset estimate; and

e. estimating channel response of at least one transmit antenna;

whereby, the frequency offset between the first information bearing unit and the second information bearing unit helps improve the channel estimation.

15. The method of claim 14 , wherein the frequency offset is equal to three sub-carriers if the number of transmit antennas is at most two and if the number of sectors in a cell is equal to three, wherein the number of transmit antennas is determined at the receiver based on the predetermined identifier.

16. The method of claim 15 , wherein the predetermined identifier and the cell identifier are transmitted simultaneously by a first transmit antenna, if the number of transmit antennas is equal to one.

17. The method of claim 15 , wherein the predetermined identifier is transmitted by a first transmit antenna and the cell identifier is transmitted by a second transmit antenna, if the number of transmit antennas is equal to two.

18. The method of claim 14 , wherein the frequency offset is equal to six sub-carriers if the number of transmit antennas is three or four and if the number of sectors in a cell is equal to three, wherein the number of transmit antennas is determined at the receiver based on the predetermined identifier.

19. The method of claim 18 , wherein the predetermined identifier is transmitted by a first transmit antenna and the cell identifier is transmitted by a remaining transmit antenna.

20. A system for enabling channel estimation and synchronization of a receiver in a block transmission system, the block transmission system being a frequency reuse system, the system comprising;

a. at least one transmit antenna, the transmit antenna transmitting a first information bearing unit and a second information bearing unit, the first information bearing unit comprising a cell identifier, the second information bearing unit being the first information bearing unit shifted by a frequency offset, wherein the combination of the first information bearing unit and the second information bearing unit is substantially periodic;

b. an offset estimator, the offset estimator obtaining at least one of coarse timing offset estimate and fractional frequency offset estimate by using the periodicity of the combination of the first information bearing unit and the second information bearing unit, the offset estimator residing on the receiver;

c. an identifier module, the identifier module identifying the cell identifier based on the at least one obtained coarse timing offset estimate and fractional frequency offset estimate, the cell identifier residing on the receiver; and

d. a channel response estimator, the channel response estimator estimating channel response of at least one transmit antenna;

whereby, the presence of frequency offset helps improve the channel estimation.

21. The system of claim 20 , wherein the block transmission system is frequency reuse-1 system.

22. The system of claim 20 , wherein the frequency offset is equal to three sub-carriers if the number of transmit antennas is at most two and the number of sectors in a cell is equal to three.

23. The system of claim 20 , wherein the frequency offset is equal to six sub-carriers if the number of transmit antennas is three or four and the number of sectors in a cell is equal to three.

24. The system of claim 20 , whereby each transmit antenna is trained simultaneously.

25. The system of claim 20 , wherein the first information bearing unit further comprises a predetermined identifier.

Assignments (8)