Simultaneous transmit and receive (STR) structures immune to phase and amplitude imbalances

• US 9,282,564 B2
• Filed: 09/18/2013
• Issued: 03/08/2016
• Est. Priority Date: 12/06/2012
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Choi, Yang-Seok
• Primary Examiner(s): Chan, Sai-Ming
• Application Number:
  US14/128,278
• Publication Number:
  US 20150009867A1
• Time in Patent Office: 902 Days
• Field of Search: 370/278
• US Class Current: 1/1
• CPC Class Codes: H04B 3/232 using phase shift, phase roll or frequency offset correction
• CPC Class Codes: H04B 7/015 Reducing echo effects
• CPC Class Codes: H04L 25/00 Baseband systems
• CPC Class Codes: H04L 25/03866 using scrambling
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 67/1068 Discovery involving direct consultation or announcement among potential requesting and potential source peers
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 72/542 using measured or perceived quality
• CPC Class Codes: H04W 76/14 Direct-mode setup
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals

Abstract

An echo-canceling unit for a simultaneous transmit and receive (STR) system includes at least three phase shifters instead of just two phase shifters in order to provide immunity to phase and/or amplitude imbalances. Each respective phase shifter is coupled to a transmit signal to generate an output signal comprising a selected phase shift with respect to the transmit signal. A weight calculation unit generates a corresponding amplitude-weight signal for the output signal of the phase shifter. A variable attenuator attenuates the output signal of each respective phase shifter based on the corresponding amplitude-weight signal to form an echo-cancelation signal component corresponding to the phase shifter. A first summer then sums the respective echo-cancelation signal components into a received signal containing an echo signal to form an echo-canceled signal. In some embodiments, an information handling system includes a receiver and a transmitter coupled to the echo-canceling unit.

Claims

1. An echo-canceler for a simultaneous transmit and receive (STR) system, comprising:

at least three phase shifters, each respective phase shifter being coupled to a transmit signal of the STR system to generate an output signal comprising a selected phase shift with respect to the transmit signal, the transmit signal comprising a 3^rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) transmit signal;

a weight calculation unit coupled to the output signal of each respective phase shifter, each weight calculation unit to generate a corresponding amplitude-weight signal for the output signal of the phase shifter;

a variable attenuator to attenuate the output signal of each respective phase shifter based on the corresponding amplitude-weight signal to form an echo-cancelation signal component corresponding to the phase shifter; and

a first summer to sum the respective echo-cancelation signal components into a received signal containing an echo signal to form an echo-canceled signal.

2. The system according to claim 1, wherein each phase shifter is a fixed-phase phase shifter.

3. The system according to claim 1, wherein a first phase shifter of the at least three phase shifters generates a nominal phase shift of 0°

with respect to the transmit signal, a second phase shifter of the at least three phase shifters generates a nominal phase shift of 60°

with respect to the transmit signal, and a third phase shifter of the at least three phase shifters generates a nominal phase shift of 120°

with respect to the transmit signal.

4. The system according to claim 1, wherein the at least three phase shifters comprise part of a vector modulator.

5. The system according to claim 1, wherein the system further comprises a plurality of vector modulators, each vector modulator comprising:

at least three phase shifters, each phase shifter being coupled to the transmit signal of the STR system at a selected tap of the transmit signal to generate an output signal comprising a selected phase shift from the transmit signal with respect to the selected tap;

a weight calculation unit coupled to the output signal of each respective phase shifter of the vector modulator to generate a corresponding amplitude-weight signal for the output signal of the phase shifter;

a variable attenuator to attenuate the output signal of each respective phase shifter based on the corresponding amplitude-weight signal to form an echo-cancelation signal component corresponding to the output signal of the phase shifter; and

a second summer to sum the respective echo-cancelation signal of the vector modulator into an echo-cancelation signal for the vector modulator, and

wherein the first summer sums the respective echo-cancelation signals of the respective vector modulators into the received signal containing an echo signal to form the echo-canceled signal.

6. The system according to claim 5, wherein a first phase shifter of the at least three phase shifters of at least one vector modulator generates a nominal phase shift of 0°

from the transmit signal with respect to the selected tap, a second phase shifter of the at least three phase shifters of the at least one vector modulator generates a nominal phase shift of 60°

from the transmit signal with respect to the selected tap, and a third phase shifter of the at least three phase shifters of the at least one vector modulator generates a nominal phase shift of 120°

from the transmit signal with respect to the selected tap.

7. The system according to claim 1, wherein each phase shifter is a variable-phase phase shifter, and

wherein the weight calculation unit is to further generate a variable-phase weight signal corresponding to the output signal of the phase shifter that varies a phase of the phase shifter.

8. The system according to claim 7, wherein each respective phase shifter is coupled to the transmit signal of the STR system at a different selected tap of the transmit signal to generate an output signal comprising a phase shift from the transmit signal with respect to the selected tap based on the variable-phase weight signal.

9. An information-handling system, comprising:

a receiver capable of receiving a signal, the received signal containing an echo signal and comprising a 3^rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) downlink signal;

a transmitter capable of transmitting a transmit signal simultaneously as the receiver receives the received signal; and

an echo-canceling unit coupled to the transmit signal and the received signal to generate an estimated echo signal, the echo-canceler comprising;

at least three phase shifters, each respective phase shifter to generate an output signal comprising a selected phase shift with respect to the transmit signal;

a first signal attenuator to attenuate the output signal of each respective phase shifter based on a weight signal corresponding to the output signal of the phase shifter to form an echo-cancelation signal component corresponding to the phase shifter; and

a second signal combiner to combine the respective echo-cancelation signal components into the received signal containing the echo signal to form an echo-canceled signal.

10. The information-handling system according to claim 9, wherein the echo-canceling unit further comprises a weight calculation unit to generate the weight signal for the output signal of the phase shifter.

11. The information-handling system according to claim 9, wherein each phase shifter is a fixed-phase phase shifter.

12. The information-handling system according to claim 9, wherein a first phase shifter of the at least three phase shifters generates a nominal phase shift of 0°

with respect to the transmit signal, a second phase shifter of the at least three phase shifters generates a nominal phase shift of 60°

with respect to the transmit signal, and a third phase shifter of the at least three phase shifters generates a nominal phase shift of 120°

with respect to the transmit signal.

13. The information-handling system according to claim 9, wherein the at least three phase shifters comprise part of a vector modulator.

14. The information-handling system according to claim 9, wherein the echo-canceling unit further comprises a plurality of vector modulators, at least one vector modulator comprising:

the at least three phase shifters; and

at least three weight calculation units, each weight calculation unit to generate a weight signal for the output signal of a corresponding phase shifter;

wherein the first signal attenuator is to attenuate the output signal of each respective phase shifter based on the corresponding weight signal to form an echo-cancelation signal component corresponding to the phase shifter; and

wherein the second signal combiner is to combine the respective echo-cancelation signal components into the received signal containing the echo signal to form the echo-canceled signal.

15. The information-handling system according to claim 14, wherein a first phase shifter of the at least three phase shifters of at least one vector modulator generates a nominal phase shift of 0°

from the transmit signal with respect to the selected tap, a second phase shifter of the at least three phase shifters of the at least one vector modulator generates a nominal phase shift of 60°

from the transmit signal with respect to the selected tap, and a third phase shifter of the at least three phase shifters of the at least one vector modulator generates a nominal phase shift of 120°

from the transmit signal with respect to the selected tap.

16. The information-handling system according to claim 9, wherein each phase shifter is a variable-phase phase shifter, and

wherein echo-canceling unit further comprises a weight calculation unit corresponding to each phase shifter to generate a variable-phase weight signal corresponding to the output signal of the phase shifter that varies a phase of the phase shifter.

17. The information-handling system according to claim 9, wherein the information-handling system comprises a cellular telephone, smartphone, smart-type device, or tablet-type device.

18. The information-handling system according to claim 17, wherein the cellular telephone, smartphone, smart-type device, or tablet-type device further comprises a touchscreen display capable of receiving input information from a touch of a user or a stylus.