Communication device with smart antenna using a quality-indication signal
View Patent ↗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.
1. A method for a first communication device to communicate with a second communication device over a communication link, the first communication device having at least first and second antenna elements, the method comprising:
transmitting a first power control group using said first and second antenna elements, wherein a signal transmitted on said first antenna has a first phase difference from a signal transmitted on said second antenna;
transmitting a second power control group using said first and second antenna elements, wherein a signal transmitted on said first antenna has a second phase difference from a signal transmitted on said second antenna;
receiving from said second communication device a first quality indication signal indicating an adjustment to power of a transmitted signal at the first communication device in a first direction;
receiving from said second communication device a second quality indication signal indicating an adjustment to power of a transmitted signal at the first communication device in a second direction;
calculating a new phase difference based on the first and second quality indication signals, wherein calculating said new phase difference comprises:
if said first direction and said second direction are opposite, then adjusting said new phase difference to optimize power; and
transmitting using said first and second antenna elements using said new phase difference.
2. The method of claim 1 , wherein calculating said new phase difference further comprises if said first direction and said second direction are identical, then maintaining said new phase difference as a current phase difference.
3. The method of claim 1 , wherein:
if said first indication requests an increase in power and said second indication requests a decrease in power, then calculating said new phase difference comprises adjusting a current phase difference in a direction of the second phase difference.
4. The method of claim 1 , wherein:
if said first indication requests a decrease in power and said second indication requests an increase in power, then calculating said new phase difference comprises adjusting a current phase difference in a direction opposite to said second phase difference.
5. The method of claim 1 , wherein a communication link between said first communication device and said second communication device is configured according to at least one Code-Division-Multiple-Access (CDMA) protocol from the group of CDMA-IS-95A/B, CDMA 2000 1X/RTT, CDMA 2000 3X, CDMA EV-DO, WCDMA, 3G Universal Mobile Telecommunications System (UMTS) and 4G UMTS.
6. The method of claim 1 , wherein said quality indication signal comprises one or more power-control bits according to CDMA protocol, each power-control bit having a value of one or zero for each time period, the power-control bit being generated by the second communication device.
7. The method of claim 1 , wherein said quality indication signal includes a first frame quality indicator according to the CDMA protocol.
8. The method of claim 1 , wherein:
the first communication device is a subscriber communication device; and
the second communication device is a basestation.
9. The method of claim 1 , wherein:
the first communication device is a basestation; and
the second communication device is a subscriber communication device.