System and method for antenna diversity using joint maximal ratio combining

A method for communicating signals between a first communication device and a second communication device using radio frequency (RF) communication techniques, comprising:

• a. applying a transmit antenna vector to a baseband signal to be transmitted from the first communication device to the second communication device, the transmit antenna weight vector comprising a complex transmit antenna weight for each of the N plurality of antennas, 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 N transmit signals each of which is weighted across the bandwidth of the baseband signal such that at substantially all frequencies of the baseband signal, the sum of the power of the transmit signals across the N plurality of antennas of the first communication device is equal to a constant;
• b. receiving at the N plurality of antennas of the first communication device at least one signal that was transmitted by the second communication device;
• c. determining a receive weight vector comprising a plurality of complex receive antenna weights for the N plurality of antennas of the first communication device from one or more signals received at the N plurality of antennas from the second communication device, wherein each receive antenna weight has a magnitude and a phase whose values may vary with frequency;
• and
• d. updating the transmit weight vector for the plurality of antennas of the first communication device for transmitting signals to the second communication device by computing a conjugate of the receive weight vector of the first communication device divided by a norm of the conjugate of the receive weight vector and repeating step (a) when transmitting back to the second communication device.

A medium encoded with instructions that, when executed, perform a method comprising steps of:

• a. applying a transmit antenna vector to a baseband signal to be transmitted from a first communication device to a second communication device, the transmit antenna weight vector comprising a complex transmit antenna weight for each of the N plurality of antennas, 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 N transmit signals each of which is weighted across the bandwidth of the baseband signal such that at substantially all frequencies of the baseband signal, the sum of the power of the transmit signals across the N plurality of antennas of the first communication device is equal to a constant;
• b. determining a receive weight vector comprising a plurality of complex receive antenna weights for the N plurality of antennas of the first communication device from one or more signals received by the N plurality of antennas from the second communication device, wherein each receive antenna weight has a magnitude and a phase whose values may vary with frequency;
• and
• c. updating the transmit weight vector for the plurality of antennas of the first communication device for transmitting signals to the second communication device by computing a conjugate of the receive weight vector of the first communication device divided by a norm of the conjugate of the receive weight vector and repeating step (a) when transmitting back to the second communication device.

A method for communicating signals from a first communication device to a second communication device using radio frequency (RF) communication techniques, comprising:

• a. transmitting a first signal by one of N plurality of antennas of the first communication device;
• b. receiving the first signal transmitted by the first communication device at two antennas of the second communication device;
• c. transmitting a first response signal from the second communication device to the first communication device using a first of two antennas at the second communication device;
• d. at the first communication device, receiving at the plurality of antennas the first response signal transmitted by the first antenna of the second communication device and deriving therefrom a first row of a channel response matrix that describes the channel response between the first communication device and the second communication device;
• e. transmitting a second signal by the plurality of antennas of the first communication device using a transmit weight vector that is orthogonal to the first row of the channel response matrix;
• f. receiving the second signal transmitted at the second communication device at the two antennas;
• g. transmitting a second response signal from the second communication device using a second of the two antennas;
• h. at the first communication device, receiving the second response signal transmitted by the second antenna of the second communication device and deriving therefrom a second row of the channel response matrix;
• and
• i. at the first communication device, selecting one of the first and second rows of the channel response matrix that provides better signal-to-noise at the second communication device as the transmit weight vector for further transmission of signals to the second communication device.

A method for communicating signals from a first communication device to a second communication device using radio frequency (RF) communication techniques, comprising:

• a. transmitting a first signal by one of N plurality of antennas of the first communication device;
• b. receiving a first response signal at the plurality of antennas of the first communication device transmitted from a first of two antennas of the second communication device;
• c. deriving a first row of a channel response matrix that describes the channel response between the first communication device and the second communication device;
• d. transmitting a second signal by the plurality of antennas of the first communication device using a transmit weight vector that is orthogonal to the first row of the channel response matrix;
• e. receiving a second response signal transmitted by a second of the two antennas of the second communication device and deriving therefrom a second row of the channel response matrix;
• and
• f. selecting one of the first and second rows of the channel response matrix that provides better signal-to-noise at the second communication device as the transmit weight vector for further transmission of signals to the second communication device.

A medium encoded with instructions that, when executed, perform steps of:

• a. generate a first signal for transmission by one of a plurality of antennas of a first communication device to a second communication device;
• b. process a first response signal received at the plurality of antennas that was transmitted from a first of two antennas of the second communication device and generating a first row of a channel response matrix that describes the channel response with the other communication device;
• c. applying to a second signal a transmit weight vector that is orthogonal to the first row of the channel response matrix for transmission via the plurality of antennas of the first communication device to the second communication device;
• d. processing a second response signal received at the plurality of antennas that was transmitted from a second of two antennas of the second communication device and generating therefrom a second row of the channel response matrix;
• and
• e. selecting one of the first and second rows of the channel response matrix that provides better signal-to-noise at the second communication device as the transmit weight vector for further transmission of signals to the other communication device.

A method for communicating signals between a first communication device and a second communication device using radio frequency (RF) communication techniques, comprising:

• a. transmitting a message from the first communication device to the second communication device to determine whether the second communication device is capable of transmitting signals back to the first communication device using an adjustable transmit weight vector;
• b. generating a training sequence comprising a sequence of N consecutive symbols, where N is a number of antennas of the first communication device, and the N symbols are multiplied by respective ones of N linearly independent vectors that span columns of a channel response matrix between the plurality of antennas of the first communication device and a plurality of antennas of the second communication device, thereby producing N transmit signals;
• c. transmitting the N transmit signals from the plurality of antennas of the first communication device;
• d. receiving the N transmit signals at each of a plurality of antennas at the second communication device;
• e. at the second communication device, deriving from signals received by the plurality of antennas the channel response matrix between the first communication device and the second communication device;
• and
• f. at the second communication device, generating a transmit weight vector from the channel response matrix for transmitting a signal from the second communication device to the first communication device using the plurality of antennas of the second communication device.

A method for communicating signals between a first communication device and a second communication device using radio frequency (RF) communication techniques, comprising:

• a. generating a training sequence comprising a sequence of N consecutive symbols, where N is a number of antennas of the first communication device, and the N symbols are multiplied by respective ones of N linearly independent vectors [1 0 . . . 0]0T, [0 1 0 . . . 0]1T, . . . , [0 0 . . . 1]N−1T, thereby producing N transmit signals;
• b. transmitting the N transmit signals from the plurality of antennas of the first communication device;
• c. receiving the N transmit signals at each of a plurality of antennas at the second communication device;
• d. at the second communication device, deriving from signals received by the plurality of antennas the channel response matrix between the first communication device and the second communication device;
• and
• e. at the second communication device, generating a transmit weight vector from the channel response matrix for transmitting a signal from the second communication device to the first communication device using the plurality of antennas of the second communication device.

A method for communicating signals between a first communication device and a second communication device using radio frequency (RF) communication techniques, comprising:

• a. applying a transmit antenna vector to a baseband signal to be transmitted from the first communication device to the second communication device, the transmit antenna weight vector comprising a complex transmit antenna weight for each of the N plurality of antennas, 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 N transmit signals each of which is weighted across the bandwidth of the baseband signal;
• b. receiving the N transmit signals at M plurality of antennas of the second communication device;
• c. determining a receive weight vector comprising a complex receive antenna weight for each of the M plurality of antennas of the second communication device from the N transmit signals received by the M plurality of antennas, wherein each receive antenna weight has a magnitude and a phase whose values may vary with frequency across a bandwidth of the baseband signal;
• d. computing a transmit weight vector comprising a plurality of complex transmit antenna weights for the M plurality of antennas of the second communication device by computing a conjugate of the receive weight vector divided by the norm of the receive weight vector;
• and
• e. applying the transmit weight vector to a baseband signal to be transmitted from the second communication device to the first communication device, thereby generating a plurality of transmit signals each of which is weighted across the bandwidth of the baseband signal to be transmitted;
• wherein steps (a) through (e) are performed for each of K frequency sub-bands of the baseband signal that correspond to sub-carriers of a multi-carrier baseband signal or to synthesized frequency sub-bands of a single carrier baseband signal, and at the first and second communication devices, further comprising a step of storing, for each of the antennas, complex transmit antenna weights for a subset of the K frequency sub-bands or sub-carriers.

A method for communicating signals between a first communication device and a second communication device using radio frequency (RF) communication techniques, comprising:

• a. applying a transmit antenna vector to a baseband signal to be transmitted from the first communication device to the second communication device, the transmit antenna weight vector comprising a complex transmit antenna weight for each of the N plurality of antennas, 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 N transmit signals each of which is weighted across the bandwidth of the baseband signal;
• b. receiving at the N plurality of antennas of the first communication device at least one signal that was transmitted by the second communication device;
• c. determining a receive weight vector comprising a plurality of complex receive antenna weights for the N plurality of antennas of the first communication device from one or more signals received at the N plurality of antennas from the second communication device, wherein each receive antenna weight has a magnitude and a phase whose values may vary with frequency;
• and
• d. updating the transmit weight vector for the plurality of antennas of the first communication device for transmitting signals to the second communication device by computing a conjugate of the receive weight vector of the first communication device divided by a norm of the conjugate of the receive weight vector;
• wherein steps (a) through (d) are performed for each of K frequency sub-bands of the baseband signal that correspond to sub-carriers of a multi-carrier baseband signal or to synthesized frequency sub-bands of a single carrier baseband signal, and further comprising the step of storing in the first communication device, for each of the N antennas, complex transmit antenna weights for a subset of the K frequency sub-bands or sub-carriers.

A medium encoded with instructions that, when executed, perform a method comprising steps of:

• a. applying a transmit antenna vector to a baseband signal to be transmitted from a first communication device to a second communication device, the transmit antenna weight vector comprising a complex transmit antenna weight for each of the N plurality of antennas, 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 N transmit signals each of which is weighted across the bandwidth of the baseband signal;
• b. determining a receive weight vector comprising a plurality of complex receive antenna weights for the N plurality of antennas of the first communication device from one or more signals received by the N plurality of antennas from the second communication device, wherein each receive antenna weight has a magnitude and a phase whose values may vary with frequency;
• and
• c. updating the transmit weight vector for the plurality of antennas of the first communication device for transmitting signals to the second communication device by computing a conjugate of the receive weight vector of the first communication device divided by a norm of the conjugate of the receive weight vector;
• and further comprising instructions for performing steps (a) through (c) at each of K frequency sub-bands of the baseband signal that correspond to sub-carriers of a multi-carrier baseband signal or to synthesized frequency sub-bands of a single carrier baseband signal, and storing in the first communication device, for each of the N antennas, complex transmit antenna weights for a subset of the K frequency sub-bands or sub-carriers.

A radio communication system comprising:

• a. a first communication device having N plurality of antennas, a baseband signal processor that generates transmit signals and that recovers data from receive signals and a radio transceiver coupled to the baseband signal processor that upconverts the transmit signals for transmission via N plurality of antennas and downconverts signals received by the N plurality of antennas to produce receive signals, wherein the baseband signal processor of the first communication device applies a transmit antenna vector to a baseband signal to be transmitted from the first communication device to the second communication device, the transmit antenna weight vector comprising a complex transmit antenna weight for each of the N plurality of antennas, 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 N transmit signals each of which is weighted across the bandwidth of the baseband signal such that at substantially all frequencies of the baseband signal, the sum of the power of the transmit signals across the N plurality of antennas of the first communication device is equal to a constant;
• and
• b. a second communication devices having M plurality of antennas, a baseband signal processor that generates transmit signals and that recovers data from receive signals and a radio transceiver coupled to the baseband signal processor that upconverts the transmit signals for transmission via M plurality of antennas and downconverts signals received by the M plurality of antennas to produce receive signals, wherein the baseband signal processor of the second communication device:
• determines a receive weight vector comprising complex receive weights for each of the M plurality of antennas from the N transmit signals received by the M plurality of antennas, wherein each receive antenna weight has a magnitude and phase whose values may vary with frequency across a bandwidth of a baseband signal derived from the N transmit signals received by the second communication device;
• computes a transmit weight vector comprising a plurality of complex transmit antenna weights for the M plurality of antennas of the second communication device by computing a conjugate of the receive weight vector divided by the norm of the receive weight vector;
• and applies the transmit weight vector to a baseband signal to be transmitted from the second communication device to the first communication device, thereby generating M plurality of transmit signals such that at substantially all frequencies of the baseband signal, the sum of the power of the transmit signals across the M plurality of antennas of the second communication device is equal to a constant.