Apparatus for antenna diversity using joint maximal ratio combining

• US 7,545,778 B2
• Filed: 09/20/2005
• Issued: 06/09/2009
• 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: Vaidyanathan, Chandra, Tesfai, Yohannes, Sugar, Gary L.
• Primary Examiner(s): Le, Nhan T
• Application Number:
  US11/231,161
• Publication Number:
  US 20060013327A1
• Time in Patent Office: 1,358 Days
• Field of Search: 370/329, 370/331, 370/332, 370/334, 370/335, 370/342, 375/148, 342/372, 455/276.1
• US Class Current: 370/335
• 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 7/0417 Feedback systems
• 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 7/0845 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 7/0848 Joint weighting
• 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 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03611 Iterative algorithms
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/0242 using matrix methods
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 27/2602 : Signal structure
• CPC Class Codes: H04L 27/2626 : Arrangements specific to the transmitter only
• CPC Class Codes: H04L 5/0007 : the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04W 52/42 : in systems with time, space, frequency or polarisation diversity

Abstract

A transceiver using composite beamforming technique is provided wherein a first communication device has a plurality of antennas and the second communication has a plurality of antennas. When the first communication device transmits to the second communication device, the transmit signal is multiplied by a transmit weight vector for transmission by each the plurality of antennas and the transmit signals are received by the plurality of antennas at the second communication device. The optimum transmit weight vector and receive weight vector for communication between the first and second communication devices is determined so that there is effectively joint or composite beamforming between the communication devices.

Claims

1. A radio communication transceiver in an orthogonal frequency division multiplexed (OFDM) system using k sub-carrier frequencies, comprising:

a symbol mapping device for mapping a baseband signal to a set of communication symbols;

N plurality of antennas, each antenna associated with a processing path;

each processing path configured to process communication symbols, comprising;

a multiplier configured to multiply the communication symbols with a plurality of complex transmit antenna weights selected for optimized transmission across the bandwidth, each complex transmit antenna weight a function of the k sub-carrier frequencies and having a magnitude and a phase;

whereby N transmit signals are generated, each of which is weighted such that at substantially all sub-carrier frequencies of the OFDM signal, the sum of the power of the transmit signals across the N plurality of antennas of the transceiver is equal to a constant.

2. The transceiver of claim 1 wherein the complex transmit antenna weights are determined without knowledge of signal to noise ratio (SNR) for another system device intended for receiving the N transmit signals.

3. The transceiver of claim 1, wherein the multiplier performs its operation in frequency domain.

4. The transceiver of claim 1, each processing path further comprising:

a buffer for storing the output values of the multiplier.

5. The transceiver of claim 1, each processing path further comprising:

an inverse Fast Fourier Transform (IFFT) device configured to convert frequency domain values into time domain for each subcarrier frequency.

6. The transceiver of claim 1, each processing path further comprising:

a lowpass filter.

7. The transceiver of claim 6, each processing path further comprising:

a digital to analog converter;

an upconverter configured to upconvert the output of the lowpass filter to an appropriate RF signal for transmission; and

a power amplifier configured to amplify the output of the upconverter.

8. The transceiver of claim 1, each processing path further comprising:

a cyclic prefix inserter.

9. The transceiver of claim 1, wherein the number of subcarriers is 52.

16. The transceiver of claim 1, each processing path further comprising:

a cyclic prefix discarding device.

10. A radio communication transceiver in an orthogonal frequency division multiplexed (OFDM) system using k sub-carrier frequencies that receives a transmitted signal from a first transmitter, comprising:

M plurality of antennas, each antenna associated with a processing path;

each processing path configured to process communication symbols, comprising;

a multiplier configured to multiply the communication symbols with a plurality of complex receive antenna weights that vary with frequency, each complex receive antenna weight a function of sub-carrier frequency and having a magnitude and a phase; and

a symbol mapping device for mapping a set of communication symbols to a baseband signal;

whereby M receive signals are generated, each of which is weighted by a function of matching to the received signal and a correlation matrix corresponding to the transmitted signal, in which at substantially all sub-carrier frequencies of the OFDM signal, the sum of the power of the transmit signals across the N plurality of transmit antennas of the first transmitter is equal to a constant.

11. The transceiver of claim 10 wherein the complex receive antenna weights are further determined by a feedback filter.

12. The transceiver of claim 10, wherein the multiplier performs its operation in frequency domain.

13. The transceiver of claim 10, each processing path further comprising:

a downconverter configured to downconvert the transmitted signal to a time domain RF signal;

an analog to digital converter; and

a lowpass filter.

14. The transceiver of claim 10, each processing path further comprising:

a buffer for storing the time domain signal in slots associated with each k sub-carrier frequency.

15. The transceiver of claim 10, each processing path further comprising:

a Fast Fourier Transform (FFT) device configured to convert time domain values into frequency domain for each k sub-carrier frequency.