System and method for antenna diversity using equal power joint maximal ratio combining

• US RE46,750 E1
• Filed: 12/08/2014
• Issued: 03/06/2018
• Est. Priority Date: 03/01/2002
• Status: Expired due to Fees

• Current Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Original Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Inventors: Sugar, Gary L., Vaidyanathan, Chandra
• Primary Examiner(s): Tarae, Michelle
• Application Number:
  US14/563,231
• Time in Patent Office: 1,184 Days
• Field of Search: 455 69
• CPC Class Codes: H01Q 3/28 varying the amplitude
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H03G 3/3089 Control of digital or coded signals
• CPC Class Codes: H04B 1/0483 Transmitters with multiple parallel paths
• CPC Class Codes: H04B 7/0465 taking power constraints at power amplifier or emission constraints, e.g. constant modulus, into account
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2025/03445 Time domain
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

An equal gain composite beamforming technique which includes the constraint that the power of the signal output by each antenna is the same, and is equal to the total power of the transmit signal divided by the number N of transmit antennas from which the signal is to be transmitted. By reducing output power requirements for each power amplifier, the silicon area of the power amplifiers are reduced by as much as N times (where N is equal to the number of transmit antennas) relative to a non-equal gain composite beamforming technique.A method and apparatus are disclosed for a multiple input multiple output (MIMO) transmission technique by a wireless communications device which includes providing that the power applied to each transmit antenna may be equal to the total power of the transmit signal divided by the number N of transmit antennas from which the signal is to be transmitted. The device may produce a weight for each of the N transmit antennas used in MIMO transmission. Also, the device may determine a total transmit power and produce a multi-carrier signal for transmission. The device may weight the multi-carrier signal for each antenna per the produced weight. Further, the device may apply a power to each of the N transmit antennas, for the weighted multicarrier signal, which is equal to the total transmit power divided by N. Each transmit antenna signal may be amplified by an amplifier coupled to that antenna.

Claims

1. A wireless communication device, comprising:

a plurality of N antennas;

a baseband processor configured to determine a receive weight vector of a plurality of complex receive antenna weights for each of the plurality of N antennas, the receive antenna weights applied to a received baseband signal;

compute a transmit weight vector by computing a conjugate of the receive weight vector, the transmit weight vector comprising a complex transmit antenna weight for each of plurality of N antennas of the communication device, wherein each complex transmit antenna weight has a magnitude and a phase whose values may vary with frequency across a bandwidth of the baseband signal, thereby generating a plurality of N transmit signals each of which is weighted across the bandwidth of the baseband signal to be transmitted from corresponding ones of the plurality of N antennas to a second communication device, wherein the magnitude of the complex transmit antenna weight associated with each antenna is such that the power to be output at each antenna is the same and is equal to the total power to be output by all of the N antennas divided by N and such that the sum of the power at each corresponding frequency across the plurality of transmit signals is equal to a constant;

apply the transmit weight vector to a baseband signal for transmission via the plurality of N antennas; and

update the transmit weight vector by repeating the determining of the receive weight vector and computing of the transmit weight vector each time signals are received to update the transmit weight vector.

2. The device of claim 1, wherein the bandwidth of the baseband signal comprises K plurality of frequency sub-bands, and the magnitude of the complex transmit antenna weights associated with each of the plurality of N antennas is such that the power to be output by each antenna is the same and is equal to 1/(KN) of the total power to be output for all of the K frequency sub-bands of the communication device.

3. The device of claim 2, further comprising a baseband memory configured to store, for each of the N antennas, complex transmit antenna weights for a subset of the K frequency sub-bands or sub-carriers.

4. The device of claim 3, wherein the baseband processor and the stored subset of complex transmit antenna N and generate therefrom the complete set of antenna weights for all of the K frequency sub-bands or sub-carriers using interpolation techniques.

5. The device of claim 1, wherein the receive weight vector, the transmit weight vector and the baseband signal of the are applied to each of K frequency sub-bands of the baseband signal that correspond to sub-carriers of a multi-carrier baseband signal or synthesized frequency sub-bands of a single carrier baseband signal.

6. A wireless communication device comprising:

a plurality of N antennas; and

a processor configured to produce a weight for each of the plurality of N antennas for use in multiple input multiple output (MIMO) transmission;

wherein the processor is further configured to determine a total transmit power;

wherein the processor is further configured to produce at least one multi-carrier signal; and

wherein the processor is further configured to weight the at least one multi-carrier signal for each of the N antennas per the produced weight;

a transmitter, operatively coupled to the processor, the transmitter and the processor configured to apply a power to each of the N antennas, for the at least one weighted multi-carrier signal, equal to the total transmit power divided by N; and

the transmitter, operatively coupled to the plurality of N antennas, the transmitter and the plurality of N antennas configured to transmit the at least one weighted multi-carrier signal.

7. The wireless communication device of claim 6 wherein an amplifier is coupled to each of the antennas.

8. The wireless communication device of claim 6 wherein the multi-carrier signal is an orthogonal frequency division multiplex signal.

9. The wireless communication device of claim 6 wherein the multi-carrier signal has a plurality of K subcarriers;

and wherein a power applied to each of the K subcarriers per antenna is equal to the total transmit power divided by KN.

10. A method comprising:

producing, by a wireless communication device, a weight for each of a plurality of N antennas for use in multiple input multiple output (MIMO) transmission;

determining, by the wireless communication device, a total transmit power;

producing, by the wireless communication device, at least one multi-carrier signal;

weighting, by the wireless communication device, the at least one multi-carrier signal for each of the N antennas per the produced weight; and

applying, by the wireless communication device, a power to each of the N antennas, for the at least one weighted multi-carrier signal, equal to the total transmit power divided by N; and

,

transmitting, by the wireless communication device, the at least one multi-carrier signal.

11. The method of claim 10 further comprising:

for each antenna, amplifying a signal, by an amplifier coupled to that antenna.

12. The method of claim 10 wherein the multi-carrier signal is an orthogonal frequency division multiplex signal.

13. The method of claim 10 wherein the multi-carrier signal has a plurality of K subcarriers;

and wherein a power applied to each of the K subcarriers per antenna is equal to the total transmit power divided by KN.