SYSTEM, METHOD AND APPARATUS FOR MOBILE TRANSMIT DIVERSITY USING SYMMETRIC PHASE DIFFERENCE

• US 20100266063A1
• Filed: 04/23/2010
• Published: 10/21/2010
• Est. Priority Date: 05/09/2002
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Chen, Phil F., HAREL, Haim, Abreu, Eduardo, Wang, Sherwin J.
• Granted Patent: US 8,249,187 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0623 Auxiliary parameters, e.g. power control [PCB] or not acknowledged commands [NACK], used as feedback information
• CPC Class Codes: H04B 7/0682 using phase diversity (e.g. phase sweeping)
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

Communication is performed for a first communication device having a set of antenna elements. A quality-indication signal is received from a second communication device (e.g., a basestation). A complex weighting is calculated based on the quality-indication signal. A pre-transmission signal is modified based on the complex transmit diversity weighting to produce a set of modified-pre-transmission signals, wherein the modifications are symmetric by making approximately half the magnitude of the transmit diversity modification to one signal in a first direction, and approximately half the magnitude of the transmit diversity modification to the other signal in a second direction, opposite the first direction. Each modified pre-transmission signal from the set of modified-pre-transmission signals is uniquely associated with an antenna element from the set of antenna elements. The set of modified-pre-transmission signals is sent from the set of antenna elements to produce a transmitted signal.

Claims

1. A mobile communication device comprising:

a processor to produce a data signal and a value of a transmit diversity parameter;

a vector modulator to produce first and second signals based on said data signal, said first signal differing from second signal based on said value of the transmit diversity parameter;

first and second antennas to transmit said first and second signals, respectively,

wherein said mobile communication device is to receive from a receiving communication device a signal quality indication pertaining to quality of the combined first and second signals as received at the receiving communication device,

wherein said processor is to determine based at least on said signal quality indication a modified value of said transmit diversity parameter,

wherein said vector modulator is to produce said first and second modified signals, said first modified signal differing from said second modified signal based on said modified value of the transmit diversity parameter, wherein said vector modulator is to modify said first signal by modifying a transmission parameter thereof in a first direction, and wherein said vector modulator is to modify said second signal by modifying said transmission parameter thereof in a second direction, opposite to said first direction, and

wherein said first and second antennas are to transmit said modified first and second signals, respectively.

2. The mobile communication device of claim 1, wherein the signal quality indication is a power control signal sent from the receiving communication device to the mobile communication device.

3. The mobile communication device of claim 1, wherein the transmit diversity parameter is a phase difference between a signal transmitted using the first antenna and a signal transmitted using the second antenna, and wherein the transmission parameter is a phase.

4. The mobile communication device of claim 3,

wherein said processor is to produce a first phase difference value based on an initial nominal phase difference value, and wherein said vector modulator is to produce first and second signals differing based on said first phase difference value, wherein said vector modulator is to modify the phase of the first signal in a first direction, and to modify the phase of the second signal in a second direction, opposite to said first direction;

wherein said mobile communication device is to receive from the receiving communication device a first signal quality indication pertaining to quality of the combined first and second signals differing based on the first phase difference value as received at the receiving communication device;

wherein said processor is to produce a second phase difference value, and wherein said vector modulator is to produce first and second signals differing based on said second phase difference value, wherein said vector modulator is to modify the phase of the first signal in the second direction, and to modify the phase of the second signal in the first direction;

wherein said mobile communication device is to receive from the receiving communication device a second signal quality indication pertaining to quality of the combined first and second signals differing by the second phase difference value as received at the receiving communication device;

wherein said processor is to determine the modified phase difference value based on a phase change step to the initial nominal phase difference value, wherein the direction of said phase change step from the initial nominal phase difference value is based at least on said first and second signal quality indications; and

wherein said first and second antennas are to transmit a data signal based on the modified nominal phase difference value.

5. The mobile communication device of claim 4, wherein the difference between the first and second phase difference values is a phase change offset value, and wherein the initial nominal phase difference is half of the phase change offset value greater than one of the first and second phase difference values and half of the phase change offset value less than the other of the first and second phase difference values.

6. The mobile communication device of claim 5, wherein the magnitude of the phase change offset is greater than or equal to the magnitude of the phase change step.

7. The mobile communication device of claim 6, wherein the magnitude of the phase change offset and the magnitude of the phase change step are each between 5 and 20 degrees.

8. The mobile communication device of claim 6, wherein the magnitude of the phase change offset and the magnitude of the phase change step are each between 10 and 15 degrees.

9. The mobile communication device of claim 6, wherein the magnitude of the phase change offset and the magnitude of the phase change step are each 12 degrees.

10. The mobile communication device of claim 5, wherein the magnitude of the phase change offset is greater than or equal to two times the magnitude of the phase change step.

11. The mobile communication device of claim 10, wherein the magnitude of the phase change offset is between 10 and 40 degrees, and the magnitude of the phase change step is between 5 and 20 degrees.

12. The mobile communication device of claim 10, wherein the magnitude of the phase change offset is between 20 and 30 degrees, and the magnitude of the phase change step is between 10 and 15 degrees.

13. The mobile communication device of claim 10, wherein the magnitude of the phase change offset is 24 degrees, and the magnitude of the phase change step is 12 degrees.

14. The mobile communication device of claim 5, wherein the magnitude of the phase change offset is greater than or equal to four times the magnitude of the phase change step.

15. The mobile communication device of claim 14, wherein the magnitude of the phase change offset is between 20 and 80 degrees, and the magnitude of the phase change step is between 5 and 20 degrees.

16. The mobile communication device of claim 14, wherein the magnitude of the phase change offset is between 40 and 60 degrees, and the magnitude of the phase change step is between 10 and 15 degrees.

17. The mobile communication device of claim 14, wherein the magnitude of the phase change offset is 48 degrees, and the magnitude of the phase change step is 12 degrees.

18. A method of modifying a signal transmitted by a mobile communication device comprising:

transmitting first and second signals from first and second antennas, respectively, said first signal differing from second signal based on a first value of a transmit diversity parameter;

receiving a signal quality indication from a receiving communication device, said signal quality indication indicating a signal quality of the combined first and second signals as received at said receiving communication device;

determining based at least on said signal quality indication a modified value of said transmit diversity parameter,

producing first and second modified signals, said first modified signal differing from said second modified signal by said modified value of the transmit diversity parameter by modifying a transmission parameter of said first signal in a first direction, and modifying the transmission parameter of said second signal in a second direction, opposite to said first direction; and

transmitting said first and second modified signals on said first and second antennas, respectively.

19. The method of claim 18, wherein the signal quality indication is a power control signal sent from the receiving communication device to the mobile communication device.

20. The method of claim 18, wherein the transmit diversity parameter is a phase difference between a signal transmitted using the first antenna and a signal transmitted using the second antenna, and wherein the transmission parameter is a phase.

21. The method of claim 20, comprising:

producing a first phase difference value based on an initial nominal phase difference value by producing first and second signals differing based on said first phase difference value, wherein the phase of the first signal is modified in a first direction, and the phase of the second signal is modified in a second direction, opposite to said first direction;

receiving from the receiving communication device a first signal quality indication pertaining to quality of the combined first and second signals differing by the first phase difference value as received at the receiving communication device;

producing a second phase difference value based on the initial nominal phase difference value by producing first and second signals differing based on said second phase difference value, wherein the phase of the first signal is modified in the second direction, and the phase of the second signal is modified in the first direction;

receiving from the receiving communication device a second signal quality indication pertaining to quality of the combined first and second signals differing by the second phase difference value as received at the receiving communication device;

determining the modified phase difference value based on a phase change step to the initial nominal phase difference value, wherein the direction of said phase change step from the initial nominal phase difference value is based at least on said first and second signal quality indications; and

transmitting a data signal based on the modified nominal phase difference value.

22. The method of claim 21, wherein the difference between the first and second phase difference values is a phase change offset value, and wherein the initial nominal phase difference is half of the phase change offset value greater than one of the first and second phase difference values and half of the phase change offset value less than the other of the first and second phase difference values.

23. The method of claim 22, wherein the magnitude of the phase change offset is greater than or equal to the magnitude of the phase change step.

24. The method of claim 23, wherein the magnitude of the phase change offset and the magnitude of the phase change step are each between 5 and 20 degrees.

25. The method of claim 23, wherein the magnitude of the phase change offset and the magnitude of the phase change step are each between 10 and 15 degrees.

26. The method of claim 23, wherein the magnitude of the phase change offset and the magnitude of the phase change step are each 12 degrees.

27. The method of claim 22, wherein the magnitude of the phase change offset is greater than or equal to two times the magnitude of the phase change step.

28. The method of claim 27, wherein the magnitude of the phase change offset is between 10 and 40 degrees, and the magnitude of the phase change step is between 5 and 20 degrees.

29. The method of claim 27, wherein the magnitude of the phase change offset is between 20 and 30 degrees, and the magnitude of the phase change step is between 10 and 15 degrees.

30. The method of claim 27, wherein the magnitude of the phase change offset is 24 degrees, and the magnitude of the phase change step is 12 degrees.

31. The method of claim 22, wherein the magnitude of the phase change offset is greater than or equal to four times the magnitude of the phase change step.

32. The method of claim 31, wherein the magnitude of the phase change offset is between 20 and 80 degrees, and the magnitude of the phase change step is between 5 and 20 degrees.

33. The method of claim 31, wherein the magnitude of the phase change offset is between 40 and 60 degrees, and the magnitude of the phase change step is between 10 and 15 degrees.

34. The method of claim 31, wherein the magnitude of the phase change offset is 48 degrees, and the magnitude of the phase change step is 12 degrees.