TECHNIQUES TO SIMULTANEOUSLY TRANSMIT AND RECEIVE OVER THE SAME RADIOFREQUENCY CARRIER

• US 20140376416A1
• Filed: 12/20/2011
• Published: 12/25/2014
• Est. Priority Date: 12/20/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Yang-Seok Choi
• Inventors: Choi, Yang-Seok
• Granted Patent: US 9,537,543 B2
• Time in Patent Office: Days
• US Class Current: 370/277
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers
• CPC Class Codes: H04B 7/015 Reducing echo effects
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex

Abstract

An apparatus may include an antenna and a transceiver coupled to the antenna, the transceiver including a receiver operative to receive a radio-frequency (RF) signal and a transmitter operative to transmit a RF signal. The apparatus may also include an RF echo cancellation module coupled to the receiver and the transmitter, the RF echo cancellation module operative to generate an analog echo cancellation signal for the received RF signal based on a delayed version of the transmit RF signal. Other embodiments are disclosed and claimed.

Claims

1-24. -24. (canceled)

25. An apparatus, comprising:

an antenna;

a transceiver coupled to the antenna, the transceiver comprising;

a receiver operative to receive a radio-frequency (RF) signal; and

a transmitter operative to transmit an RF signal; and

an RF echo cancellation module coupled to the receiver and the transmitter, the RF echo cancellation module operative to generate an analog echo cancellation signal for the received RF signal based on a delayed version of the transmit RF signal.

26. The apparatus of claim 25, the receiver comprising a multiplier operative to receive as input the received RF signal and the analog echo cancellation signal, multiply the received RF signal and the analog echo cancellation signal, and output an echo cancelled RF signal.

27. The apparatus of claim 26, the receiver comprising a low noise amplifier coupled to the multiplier, the low noise amplifier operative to receive the echo cancelled RF signal and amplify the echo cancelled RF signal.

28. The apparatus of claim 25, comprising a two-tap filter having first and second respective delays τ

₁ and τ

₂, the two-tap filter being arranged to receive an upconverted signal x(t) and to output first and second delayed upconverted signals x(t−

τ

₁) and x(t−

τ

₂) to the RF echo cancellation module.

29. The apparatus of claim 28,

the upconverted signal comprising a bandwidth BW, and

a product of the bandwidth and absolute value of the difference of the first and second delays BW|(τ

₁−

τ

₂)| being less than 0.2.

30. The apparatus of claim 25, the RF echo cancellation module comprising a vector modulator to:

receive a filtered component signal x(t−

τ

) of the upconverted signal to be transmitted; and

output an echo cancellation signal based on a transform of the filtered component signal.

31. The apparatus of claim 25, the RF echo cancellation module comprising a weight calculator to:

receive in phase and quadrature echo cancelled received signal components z_i(t) and z_q(t);

receive in phase and quadrature downconverted transmit signals {tilde over (x)}_1,i(t) and {tilde over (x)}_1,q(t), respectively;

add products {tilde over (x)}_1,i (t) z_i(t) and {tilde over (x)}_1,q(t) z_q(t) to form an in phase weight vector w_1,i; and

add products {tilde over (x)}_1,i(t) z_q(t) and {tilde over (x)}_1,q(t) z_i(t) to form the quadrature weight vector w_1,q.

32. The apparatus of claim 31, the vector modulator comprising:

a delay module to apply a delay to a first portion of the filtered component signal;

a Hilbert transform module to output a Hilbert transform of a second portion of the filtered component signal {circumflex over (x)}(t−

τ

₁);

a first multiplier to output a product of the delayed filtered component multiplied by the in-phase weight vector for estimating echo w_1,ix(t−

τ

₁); and

a second multiplier to output a product of the delayed filtered component multiplied by the quadrature weight vector for estimating echo w_1,q{circumflex over (x)}(t−

τ

₁).

33. The apparatus of claim 25, comprising a baseband echo cancellation module arranged to:

determine a weight vector W for a two-tap Wiener filter to minimize power of a baseband echo cancelled signal Z(t) from a received signal Y(t), where

Z(t)=Y(t)−

W₁X(t−

τ

₁)e<sup>jω

τ

1</sup>−

W₂X(t−

τ

₂)e<sup>jω

τ

2</sup>=Y(t)−

W^TX(t), where

W_k=w_k+jw_k,q and W=[W₁ W₂]^T and where

τ

₁ and τ

₂ are delays of the two-tap Wiener filter.

34. The apparatus of claim 33, the baseband echo cancellation module arranged to update W according to W=W+μ

X*(t)Z(t), where μ

equals step size.

35. The apparatus of claim 25, comprising a digital display to present information received in a received echo-cancelled signal derived from the analog echo cancellation signal.

36. A method, comprising:

receiving a radio-frequency (RF) signal Y(t) over a first time interval; and

generating a first echo cancellation signal to provide echo cancellation after the received RF signal Y(t) is downconverted to a baseband signal Z(t) in a baseband frequency range;

generating an upconverted signal x(t) to be transmitted during the first time interval; and

generating a second echo cancellation signal to provide echo cancellation between an upconverted signal x(t) to be transmitted and the received RF signal Y(t).

37. The method of claim 36, comprising:

filtering the upconverted signal x(t) using a multiple-tap filter comprising two or more delays; and

outputting an echo cancellation signal based upon the filtered upconverted signal.

38. The method of claim 36, comprising:

filtering the upconverted signal x(t) using a two-tap filter comprising a first delay τ

₁ and second delay τ

₂;

outputting an echo cancellation signal based upon the filtered upconverted signal.

39. The method of claim 36, comprising:

applying a delay to a first portion of a filtered component signal x(t−

τ

₁);

performing a Hilbert transform on a second portion of the filtered component signal;

outputting a product of the delayed filtered component multiplied by an in-phase weight vector for estimating echo w_1,ix(t−

τ

₁); and

outputting a product of the delayed filtered component multiplied by a quadrature weight vector for estimating echo w_1,q{circumflex over (x)}(t−

τ

₁).

40. The method of claim 36, comprising:

setting a product of bandwidth BW of the upconverted signal x(t) and absolute value of the difference of first and second delays, BW|(τ

₁−

τ

₂)|, to equal less than 0.2.

41. The method of claim 36, comprising:

generating in phase and quadrature echo cancelled received baseband signal components z_i(t) and z_q(t), respectively;

generating in phase and quadrature downconverted transmit signals {tilde over (x)}_1,i(t) and {tilde over (x)}_1,q(t), respectively;

adding products {tilde over (x)}_1,i(t) z_i(t) and {tilde over (x)}_1,q(t) z_q(t) to form an in phase weight vector w_1,i; and

adding products {tilde over (x)}_1,i(t) z_q(t) and {tilde over (x)}_1,q(t) z_i(t) to form a quadrature weight vector w_1,q; and

applying w_1,i and w_1,q to the upconverted signal x(t).

42. At least one computer-readable storage medium comprising a plurality of instructions that, when executed, cause a system to generate an analog echo cancellation signal for a received RF signal based on a delayed version of an transmit RF signal.

43. The at least one computer-readable storage medium of claim 42 comprising instructions that, when executed, cause a system to:

receive a filtered component signal x(t−

τ

) of the upconverted signal to be transmitted; and

output an echo cancellation signal based on a transform of the filtered component signal.

44. The at least one computer-readable storage medium of claim 42 comprising instructions that, when executed, cause a system to:

receive in phase and quadrature echo cancelled received signal components z_i(t) and z_q(t);

receive in phase and quadrature downconverted transmit signals {tilde over (x)}_1,i(t) and {tilde over (x)}_1,q(t), respectively;

add products {tilde over (x)}_1,i(t) z_i(t) and {tilde over (x)}_1,q(t) z_q(t) to form an in phase weight vector w_1,i; and

add products {tilde over (x)}_1,i(t) z_q(t) and {tilde over (x)}_1,q(t) z_i(t) to form the quadrature weight vector w_1,q.

45. The at least one computer-readable storage medium of claim 43 comprising instructions that, when executed, cause a system to:

apply a delay to a first portion of the filtered component signal;

output a Hilbert transform of a second portion of the filtered component signal {circumflex over (x)}(t−

τ

₁);

output a product of the delayed filtered component multiplied by the in-phase weight vector for estimating echo w_1,ix(t−

τ

₁); and

output a product of the delayed filtered component multiplied by the quadrature weight vector for estimating echo w_1,q{circumflex over (x)}(t−

τ

₁).