Communication device with smart antenna using a quality-indication signal

• US 20030002594A1
• Filed: 05/09/2002
• Published: 01/02/2003
• Est. Priority Date: 05/31/2001
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Magnolia Broadband Incorporated
• Inventors: Harel, Haim, Li, Yingxue, Segalovitz, Alexander
• Granted Patent: US 7,321,636 B2
• Time in Patent Office: Days
• US Class Current: 375/299
• 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 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/221 using past power control commands
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
• 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 weighting to produce a set of modified-pre-transmission signals. 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. The complex weighting is associated with a total power of the transmitted power and at least one from a phase rotation and a power ratio associated with each antenna element from the set of antenna elements. For example, in CDMA based systems, a fast feedback from the basestation—the power control indication—can be used by a subscriber communication device for this transmission diversity method in such a way that provides the desired signal quality at the basestation, without necessarily responding to fading nulls by mobile unit power output increase, but rather, by manipulating the weights of the mobile transmitter antenna array. Thus, a significant reduction in average and peak mobile power level is achieved, enhancing network capacity, battery life, and radiation hazards.

Claims

1. A method for a first communication device to communicate with a second communication device over a communication link, the first communication device having a plurality of antenna elements, the method comprising:

receiving a quality-indication signal from the second communication device;

calculating a complex weighting based on the quality-indication signal;

modifying a pre-transmission signal based on the complex weighting to produce a plurality of modified pre-transmission signals, each modified pre-transmission signal from the plurality modified pre-transmission signals being uniquely associated with an antenna element from a plurality antenna elements; and

sending the plurality of modified pre-transmission signals from the plurality of antenna elements to produce an effective combined transmitted signal,

the complex weighting being associated with a total power of the transmitted signal and at least one from a phase rotation and a power ratio associated with each antenna element from the plurality of antenna elements.

2. The method of claim 1, wherein:

the total power of the transmitted signal is optimized with respect to a fading associated with a channel between the first communication device and the second communication device.

3. The method of claim 1, wherein:

the communication link is configured according to at least one Code-Division-Multiple-Access (CDMA) protocol from the group of CDMA-IS-95 A/B, CDMA 2000 1X/RTT, CDMA 2000 3X, CDMA EV-DO, WCDMA, 3G Universal Mobile Telecommunications System (UMTS) and 4G UMTS.

4. The method of claim 3, wherein:

the quality-indication signal is a power-control bit according to the CDMA protocol, the power-control bit having a value of one or zero for each time period from a plurality of time periods, the power-control bit being generated by the second communication device and indicating an adjustment to a power of the transmitted signal at the first communication device so that a predetermined threshold requirement for the second communication device can be satisfied.

5. The method of claim 4, wherein:

the complex weighting is associated with the total power of the transmitted signal and the phase rotation associated with each antenna element from the plurality of antenna element.

6. The method of claim 5, wherein the calculating of the complex weighting includes:

substantially optimizing the total power of the transmitted signal and the phase rotation associated with each antenna element from the plurality of antenna elements in parallel while maintaining a power ratio associated with each antenna element from the plurality of antenna elements.

7. The method of claim 5, wherein the calculating of the complex weighting is performed for each antenna element from the plurality of antenna elements and includes:

adjusting the total power of the transmitted signal while maintaining the phase rotation associated with antenna element from the plurality of antenna elements until a steady state is obtained at a first time;

adjusting the phase rotation associated with each antenna element from the plurality of antenna elements while maintaining the total power of the transmitted signal to produce an optimal phase rotation for each antenna element; and

adjusting the total power of the transmitted signal while maintaining the optimal phase rotation for each antenna element until a second steady state is obtained at a second time subsequent to the first time.

8. The method of claim 5, wherein:

the plurality of antenna elements includes only a first antenna element and a second antenna element.

9. The method of claim 8, wherein:

the transmitted signal includes a first adjacent power control group (PCG) and a second PCG so that a power associated the first PCG and a power associated with the second PCG are substantially at a same level P, the first PCG being associated with its own phase rotation having a value, the second PCG being associated with its own phase rotation having the value of the first PCG plus an offset; and

the calculating of the complex weighting includes;

adjusting the total power of the transmitted signal while maintaining the phase rotation associated with the first PCG and the phase rotation associated with the second PCG if the value for the power-control bit at the most recent time period corresponds to the value for the power-control bit at a second most recent time period; and

adjusting the phase rotation associated with the first PCG and the phase rotation associated with the second PCG while maintaining the total power of the transmitted signal if the value for the power-control bit at the most recent time period differs from the value for the power-control bit at the second most recent time period.

10. The method of claim 8, wherein the calculating of the complex weighting includes:

detecting a steady state in the quality-indication signal;

adjusting the phase rotation associated with the second antenna element;

selecting a first direction for the phase rotation associated with the second antenna element, the first direction being selected to improve a received signal quality at the second communication device; and

adjusting the phase rotation associated with the second antenna element in the first direction until a boundary is detected.

11. The method of claim 8, wherein the calculating of the complex weighting includes:

detecting a steady state in the quality-indication signal at a first time;

adjusting the phase rotation associated with the second antenna element;

selecting a first direction for the phase rotation associated with the second antenna element, the first direction being selected to improve a received signal quality at the second communication device; and

adjusting the phase rotation associated with the second antenna element in the first direction until a second steady state is detected in the quality-indication signal at a second time subsequent to the first time.

12. The method of claim 4, wherein:

the complex weighting is associated with the total power of the transmitted signal, the phase rotation associated with each antenna element from the plurality of antenna element and the power ratio associated with each antenna element from the plurality of antenna elements.

13. The method of claim 12, wherein the calculating of the complex weighting includes:

substantially optimizing the total power of the transmitted signal and the phase rotation associated with each antenna element from the plurality of antenna elements in parallel while maintaining a power ratio associated with each antenna element from the plurality of antenna elements; and

substantially optimizing the total power of the transmitted signal and a power ratio associated with each antenna element from the plurality of antenna elements in parallel while maintaining the phase rotation associated with each antenna element from the plurality of antenna elements.

14. The method of claim 12, wherein the calculating the complex weighting includes:

adjusting the total power of the transmitted signal while maintaining the phase rotation and the power ratio associated with each antenna element from the plurality of antenna elements until a steady state is detected in the quality-indication signal;

adjusting the phase rotation associated with each antenna element from the plurality of antenna elements while maintaining the total power of the transmitted signal and a power ratio associated with each antenna element from the plurality of antenna elements;

adjusting a total power of the transmitted signal while maintaining the phase rotation and the power ratio associated with each antenna element from the plurality of antenna elements;

adjusting the power ratio associated with each antenna element from the plurality of antenna elements while maintaining the total power associated with the transmitted signal and the phase rotation associated with each antenna element from the plurality of antenna elements; and

adjusting the total power of the transmitted power while maintaining the phase rotation and the power ratio associated with each antenna element from the plurality of antenna elements.

15. The method of claim 12, wherein the plurality of antenna elements is a first antenna element and a second antenna element.

16. The method of claim 15, wherein:

the transmitted signal includes a first adjacent power control group (PCG) and a second PCG so that a power associated the first PCG and a power associated with the second PCG are substantially at a same level P, the first PCG being associated with its own phase rotation having a value and its own power ratio having a value, the second PCG being associated with its own phase rotation having the phase rotation value of the first PCG plus a phase offset and its own power ratio having the power ratio value of the first PCG plus a power ratio offset; and

the calculating of the complex weighting includes;

adjusting the total power of the transmitted signal while maintaining the phase rotation associated with the first PCG and the phase rotation associated with the second PCG if the value for the power-control bit at the most recent time period corresponds to the value for the power-control bit at a second most recent time period;

adjusting the phase rotation associated with the first PCG and the phase rotation associated with the second PCG while maintaining the total power of the transmitted signal if the value for the power-control bit at the most recent time period differs from the value for the power-control bit at the second most recent time period;

adjusting the total power of the transmitted signal while maintaining the power ratio associated with the first PCG and the power ratio associated with the second PCG if the value for the power-control bit at the most recent time period corresponds to the value for the power-control bit at the second most recent time period; and

adjusting the power ratio associated with the first PCG and the power ratio associated with the second PCG while maintaining the total power of the transmitted signal if the value for the power-control bit at the most recent time period differs from the value for the power-control bit at the second most recent time period.

17. The method of claim 15, wherein the calculating the complex weighting includes:

adjusting the phase rotation associated with each antenna element from the plurality of antenna elements while maintaining the total power of the transmitted signal and a power ratio associated with each antenna element from the plurality of antenna elements;

after adjusting the phase rotation, adjusting the power ratio associated with each antenna element from the plurality of antenna elements while maintaining the total power associated with the transmitted signal and the phase rotation associated with each antenna element from the plurality of antenna elements.

18. The method of claim 15, wherein:

the calculating of the complex weighting includes;

adjusting the total power of the transmitted signal while maintaining the phase rotation associated with the first PCG and the phase rotation associated with the second PCG and while maintaining the power ratio associated with the first PCG and the power ratio associated with the second PCG.

19. The method of claim 3, wherein:

the quality-indication signal includes a first frame quality indicator according to the CDMA protocol.

20. The method of claim 1, wherein:

the first communication device is a subscriber communication device; and

the second communication device is a basestation.

21. The method of claim 1, wherein:

the first communication device is a basestation; and

the second communication device is a subscriber communication device.

22. The method of claim 1, wherein:

the communication link is configured according to at least one Time Division Multiple Access (TDMA) protocol.

23. The method of claim 22, wherein:

the complex weighting is associated with the total power of the transmitted signal and the phase rotation associated with each antenna element from the plurality of antenna element, but not the power ratio associated with each antenna element from the plurality of antenna elements.

24. The method of claim 22, wherein the calculating of the complex weighting includes:

substantially optimizing the total power of the transmitted signal and the phase rotation associated with each antenna element from the plurality of antenna elements in parallel while maintaining a power ratio associated with each antenna element from the plurality of antenna elements.

25. The method of claim 22, wherein:

the calculating of the complex weighting is performed for each antenna element from the plurality of antenna elements including;

adjusting the total power of the transmitted signal while maintaining the phase rotation associated with antenna element from the plurality of antenna elements until a steady state is obtained at a first time;

adjusting the phase rotation associated with each antenna element from the plurality of antenna elements while maintaining the total power of the transmitted signal to produce an optimal phase rotation for each antenna element; and

adjusting the total power of the transmitted signal while maintaining the optimal phase rotation for each antenna element until a second steady state is obtained at a second time subsequent to the first time.

26. The method of claim 1, wherein:

the communication link is configured according to at least one frequency division multiple access (FDMA) protocol.

27. The method of claim 26, wherein:

the complex weighting is associated with the total power of the transmitted signal and the phase rotation associated with each antenna element from the plurality of antenna element, but not the power ratio associated with each antenna element from the plurality of antenna elements.

28. The method of claim 26, wherein the calculating of the complex weighting includes:

substantially optimizing the total power of the transmitted signal and the phase rotation associated with each antenna element from the plurality of antenna elements in parallel while maintaining a power ratio associated with each antenna element from the plurality of antenna elements.

29. The method of claim 26, wherein:

the calculating of the complex weighting is performed for each antenna element from the plurality of antenna elements including;

adjusting the total power of the transmitted signal while maintaining the phase rotation associated with antenna element from the plurality of antenna elements until a steady state is obtained at a first time;

adjusting the phase rotation associated with each antenna element from the plurality of antenna elements while maintaining the total power of the transmitted signal to produce an optimal phase rotation for each antenna element; and

adjusting the total power of the transmitted signal while maintaining the optimal phase rotation for each antenna element until a second steady state is obtained at a second time subsequent to the first time.

30. A method for improving system performance of a communication device, comprising:

receiving a quality-indication signal and a pre-transmission signal;

dividing the pre-transmission signal into a first signal component and a second signal component;

adjusting at least one characteristic associated with at least one from the group of the first signal component and the second signal component based on the quality-indication signal, the at least one characteristic being from the group of a power ratio and a phase rotation; and

combining the first signal component and the second signal component to produce a transmit signal component uniquely associated with an antenna element from a plurality of antenna elements, the transmit signal component for each antenna element from the plurality of antenna elements being a low-correlation version of the pre-transmission signal.

31. The method of claim 30, wherein:

the quality-indication signal is a CDMA power-control signal, the power-control signal having an increase indication, a decrease indication or a steady-state indication for each time period;

the adjusting the phase rotation for each antenna element from the plurality of antenna elements includes;

changing the phase rotation associated with the first signal component until a power-control signal has the increase indication for a second time period subsequent to a first time period.

32. The method of claim 31, wherein:

the adjusting the power ratio for each antenna element from the plurality of antenna elements, includes;

measuring, for each antenna element from the plurality of antenna elements, the power ratio associated with the transmit signal component associated with that antenna element when the remaining antenna elements from the plurality of antenna elements are disabled;

recording a power ratio associated with each antenna element relative to the remaining antenna elements from the plurality of antenna elements; and

adjusting the power ratio associated with at least one from the group of the first signal component and the second signal component for each antenna element from the plurality of antenna elements so that the power ratio associated with each antenna element is substantially maintained.

33. The method of claim 32, wherein the adjusting the power is performed subsequent to the adjusting the phase.

35. The apparatus of claim 34, wherein:

each circuit from the plurality of circuits has;

a filter, the filter configured to receive a pre-transmission signal and produce a first pre-transmission signal component and a second pre-transmission signal component;

a first signal adjuster coupled to the filter, the first signal adjuster configured to receive the first pre-transmission signal component and a complex weight from the plurality of complex weights, the first signal adjuster configured to send a modified-pre-transmission signal based on the complex weight for the first signal adjuster; and

a second signal adjuster coupled to the filter, the second signal adjuster configured to receive the second signal component and a complex-weight signal from the plurality of complex-weight signals, the second signal adjuster configured to send a modified-pre-transmission signal based on the complex weight for the second signal adjuster.

36. The apparatus of claim 35, wherein:

the first signal adjuster is configured to modify at least one characteristic associated with the first pre-transmission signal component based on the complex weight received by the first signal adjuster, the at least one characteristic being from the group of a power and a phase rotation; and

the second signal adjuster is configured to modify at least one characteristic associated with the second pre-transmission signal component based on the complex weight received by the second signal adjuster, the at least one characteristic being from the group of a power and a phase rotation.

37. The apparatus of claim 36, further comprising:

a plurality of antenna elements coupled to the plurality of circuits, the plurality of antenna elements being configured to send the plurality of modified-pre-transmission signals to produce a transmitted signal, the transmitted signal being configured to have an optimized power when received by a second communication device.

38. The apparatus of claim 34, wherein:

the total power of the transmitted signal is substantially optimized with respect to a fading associated with a channel between the first communication device and a second communication device.

39. The apparatus of claim 32, wherein:

the transmitted signal is sent by the first communication device based on at least one code-division multiple access (CDMA) protocol.

40. The apparatus of claim 37, wherein:

each circuit from the plurality of circuits further includes;

an analog-to-digital converter coupled to the filter; and

a digital-to-analog converter coupled to the first signal adjuster and the second signal adjuster;

the first signal component produced by the filter is an in-phase pre-transmission signal; and

the second signal component produced by the filter is a quadrature pre-transmission signal.

41. The apparatus of claim 37, wherein:

the transmitted signal is sent by the first communication device based on at least one time-division multiple access (TDMA) protocol.

42. The apparatus of claim 37, wherein:

the transmitted signal is sent by the first communication device based on at least one frequency-division multiple access (FDMA ) protocol.

34. A first communication device having a plurality of antenna elements, comprising:

a control-logic component, the control-logic component receiving a quality-indication signal and producing a plurality of complex weights; and

a plurality of circuits coupled to the control-logic component, each circuit from the plurality of circuits being uniquely associated with an antenna element from the plurality of antenna elements, each circuit from the plurality of circuits producing a modified-pre-transmission signal based on the plurality of complex weights,

the plurality of complex weights being associated with a total power of a transmitted signal and at least one from a phase rotation and a power ratio associated with each antenna element from the plurality of antenna elements.

43. A first communication device, comprising:

a baseband system, the baseband system configured to send a pre-transmission signal;

a quality-indication based signal modifier coupled to the baseband system, the quality-indication based signal modifier configured to modify a characteristic of the pre-transmission signal based on a quality-indication signal to produce a plurality of modified- pre-transmission signal; and

a plurality of antenna elements coupled to the quality-indication based signal modifier, each modified-pre-transmission signal from the plurality modified-pre-transmission signals being uniquely associated with an antenna element from the plurality antenna elements, each modified-pre-transmission signal from the plurality of modified-pre-transmission signal being a low-correlation version of the pre-transmission signal.

44. The first communication device of claim 43, wherein the quality-indication based signal modifier includes a vector modulator, the vector modulator including a filter, a first signal adjuster and a second signal adjuster, the filter configured to split the pre-transmission signal into a first signal component and a second signal component, the first signal adjuster configured to adjust the first signal component based on a complex weight associated with the quality-indication signal, the second signal adjuster configured to adjust the second signal component based on a complex weight associated with the quality-indication signal.

45. The first communication device of claim 43, wherein:

the plurality of antenna elements are configured to send the plurality of modified-pre-transmission signal to produce a transmitted signal, the transmitted signal being configured to have an optimized power when received by a second communication device.

46. The first communication device of claim 43, wherein:

the power of the transmitted signal is optimized with respect to a fading associated with a channel between the first communication device and a second communication device.