EP3146646A1 - Blind technique for weight selection in simultaneous transmit and receive structure - Google Patents
Blind technique for weight selection in simultaneous transmit and receive structureInfo
- Publication number
- EP3146646A1 EP3146646A1 EP14892294.1A EP14892294A EP3146646A1 EP 3146646 A1 EP3146646 A1 EP 3146646A1 EP 14892294 A EP14892294 A EP 14892294A EP 3146646 A1 EP3146646 A1 EP 3146646A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- value
- signal
- weight
- echo
- cost function
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B3/00—Line transmission systems
- H04B3/02—Details
- H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
- H04B3/23—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers
- H04B3/232—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers using phase shift, phase roll or frequency offset correction
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
- H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
- H04B7/0842—Weighted combining
- H04B7/0848—Joint weighting
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
- H04B1/50—Circuits using different frequencies for the two directions of communication
- H04B1/52—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
- H04B1/525—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa with means for reducing leakage of transmitter signal into the receiver
Definitions
- Embodiments pertain to wireless communications. Some embodiments relate to transmission of signals in wireless networks including those networks that operate based on a 3GPP Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Long-Term-Evolution (LTE-A) advanced network standard.
- E-UTRAN Evolved Universal Terrestrial Radio Access Network
- LTE-A Long-Term-Evolution
- weights are often used to control the value of an echo-cancelling signal generated by an echo-canceller of the system.
- the echo -canceller may use the echo-cancelling signal to cancel an unwanted echo signal in a receiving path of the system.
- the echo signal may be part of a signal from a transmitting path of the system that leaks into the receiving path.
- the values of the weights are often selected, such that the value of echo-cancelling signal may be as close to the value of the echo signal as possible in order to have an effective echo-cancelling operation.
- techniques for selecting such values for the weights may lead to complex echo-cancellation structure, slow cancellation operation, or both.
- FIG. 1 is a block diagram of a wireless communication system including an echo-canceller, according to some embodiments described herein.
- FIG. 2 is a flowchart showing a method for operating a wireless communication system including an operation for selecting weighs to control attenuators of an echo-canceller, according to some embodiments described herein.
- FIG. 3 shows a wireless communication network including a network station and wireless communication devices, according to some embodiments described herein.
- FIG. 4 shows a block diagram of a wireless communication device including echo-canceller, according to some embodiments described herein.
- FIG. 1 is a block diagram of a wireless communication system
- Wireless communication system 100 may have simultaneous transmit (Tx) and receive (Rx) (STR) capability (e.g., a full-duplex capability), such that it can simultaneously transmit and receive signals.
- wireless communication system 100 may include an antenna 102 to receive an incoming signal r(t), a receiver 110, and a transmitter 120.
- Receiver 110 may include a low noise amplifier (LNA) 111, a down converter 112, and an analog-to -digital (ADC) 113, all arranged to process signals from antenna 102.
- LNA low noise amplifier
- ADC analog-to -digital
- Transmitter 120 may include a digital-to-analog converter (DAC) 121, an up converter 122, and a power amplifier (PA) 123, all arranged to generate an analog signal x(t) based on a digital signal x(n) for transmission from wireless communication system 100 to other devices.
- DAC digital-to-analog converter
- PA power amplifier
- y(t) may include a combination of a desired signal sent to wireless communication system 100 from another device or system plus the echo.
- echo- canceller 101 is arranged to perform an echo-cancellation operation to estimate the echo, generate an echo-cancelling signal, and then subtract the echo- cancelling signal from the received signal containing the echo y(t) to generate an echo-canceled signal z(t).
- the echo-cancelling signal may include the combination (e.g., a sum) of signals Xi(t) and x 2 (t), which are output signals at the output of echo-canceller 101.
- Echo-canceller 101 may subtract signals Xi(t) and x 2 (t) from received signal containing the echo y(t) to generate echo-canceled signal z(t).
- Signal Xi(t) and signal x 2 (t) may be generated based on signals from selected taps on a signal path of transmitted signal x(t).
- T > 2 may be used to generate an echo- cancelling signal (the combination of signals Xi(t) and x 2 (t)) at the output of echo-canceller 101.
- FIG. 1 shows two vector modulators 131 and 132 for generating two
- the number of vector modulators may vary.
- the values of signal xi(t) and signal x 2 (t) may be controlled by the values of weights used in the corresponding vector modulator.
- weights wi, w 2 , and W3 may be used in vector modulator 131 to control the value of signal Xi(t).
- Weights w 4 , w 5 , and W6 may be used in vector modulator 132 to control the value of signal x 2 (t).
- values of signals xi(t) and x 2 (t) used to cancel the echo may be appropriately be obtained.
- Echo-canceller 101 may include a weight calculator 160 arranged to calculate and select values for weights wi through Wk- Weight calculator 160 may use a signal Z(n) in the calculation for the values for weights wi through Wk.
- Signal Z(n) is a digital baseband signal generated based on echo-canceled signal z(t).
- weight calculator 160 may use a signal Z(n) in an operation of calculating and selecting the values for weights wi through Wk without using components associated with transmitted signal x(t) (or x(n)) as inputs for calculating the values for these weights during the operation.
- echo -canceller 101 may be less complex than the structure or operation of an echo -canceller 101 that uses components associated with transmitted signal x(t) (or x(n)) as inputs for calculating the values for the weights. Further, without using components associated with transmitted signal x(t) (or x(n)) as inputs for calculating the values for the weights, echo -canceller 101 may be relatively faster and less sensitive to RF impairments.
- echo-canceller 101 may include a delay 103 coupled to the transmit path of transmitter 120.
- Delay 103 may provide a time delay to compensate for delays in other components (e.g., vector modulators 131 and 132 and summer 155) in the echo estimation path (e.g., path may be between delay ⁇ ⁇ and summer 155) of echo-canceller 101 that are used in the generation echo-cancelling signals (e.g., xi(t) and x 2 (t)).
- the value of delay 103 may be selected to make sure the delay of echo is between the values of delays of x(t) in xi(t) and x 2 (t)).
- Vector modulators 131 and 132 may include similar, or identical, components. Thus, for simplicity, detail of only vector modulator 131 is shown in FIG. 1.
- Phase shifters 141 , 142, and 143 may be arranged for different fixed phase shifts (e.g., 0°, 60°, and 120°, respectively) with respect to transmitted signal x(t). Phase shifters 141 , 142, and 143 generate corresponding output signals at their outputs.
- the output signals may be attenuated by an attenuator unit, which may include a variable or stepped attenuator unit.
- the attenuator unit may include attenuators 151 , 152, and 153. Attenuators 151 , 152, and 153 may include variable or stepped attenuators.
- Attenuators 151 , 152, and 153 may be controlled by a group of weights wi, w 2 , and W3, as shown in FIG. 1. Attenuators 151 , 152, and 153 generate attenuated signals at their outputs. Each of the attenuated signals corresponds to the output signal of one of the phase shifters 141, 142, and 143. The attenuated signals at the outputs of attenuator 151, 152, and 153 may be summed by a summer 154 to generate signal Xi(t), which is one of the output signals at the output of echo -canceller 101.
- Vector modulator 132 may include fixed -phase phase shifters, attenuators (e.g., variable or stepped attenuators), and a summer, similar to, or identical to, those of vector modulator 131 shown in FIG. 1.
- the output signals at the outputs of the phase shifters may be attenuated by an attenuator unit (e.g., a variable or stepped attenuator unit).
- the attenuators (e.g., variable or stepped attenuators) in the attenuator unit may be controlled by a group of weights W4, w 5 , and w 3 ⁇ 4 .
- the attenuated signals at the outputs of the attenuators of vector modulator 132 may be summed by the summer in vector modulator 132 to generate signal x 2 (t), which is another output signal at the output of echo -canceller 101).
- Summer 155 may be arranged to sum signals Xi(t) and x 2 (t) and the received signal containing the echo y(t) to generate echo-canceled signal z(t).
- weight calculator 160 may use signal Z(n) in an operation of calculating and selecting values for weights wi through Wk.
- Weight calculator 160 may select the values for weights wi through Wk by performing an operation to search the values of the weights. The search may be based on a minimization of the cost function of signal Z(n).
- the cost function may be expressed as
- Equation (1) the cost function is a quadratic function of the weight vector.
- the local minimum of the cost function is the global minimum of the cost function. Therefore, the values for weights wi through Wk may be selected by searching for a value of the weight that falls on the global minimum of the cost function, which is also the smallest value of the power of signal Z(n). Thus, a particular value of a weight can be selected by searching for the smallest value of the power of signal Z(n).
- signal Z(n) may be generated from echo- canceled signal z(t) using a path that may include a band-pass filter 161, a variable gain amplifier (VGA) 162 to modify (e.g., amplify) echo-canceled signal z(t), a down converter 163 to down-convert echo-canceled signal z(t) after it modified by VGA 162 to generate a baseband signal, and an analog-to-digital converter (ADC) 164 to convert echo-canceled signal z(t) after it is modified by VGA 162 and down-converted by down converter 163 to generate signal Z(n).
- Weight calculator 160 of echo -canceller 101 may include a periodic
- the operation of VGA 162 may change the power of signal Z(n).
- the value of the power of signal Z(n) may be compensated by a compensated value (e.g., 1/g 2 ) as shown in Equation (3)) by a unit 166. Therefore, the cost function of signal Z(n) with compensation for the gain of VGA 162 may be based on equation
- g is defined as the gain of VGA 162 in linear scale.
- communication system 100 may communicate with other systems or devices using orthogonal frequency division multiple (OFDM) access.
- OFDM orthogonal frequency division multiple
- an OFDM signal can be averaged over an OFDM symbol or integer multiple of OFDM symbols.
- the weight may be fixed.
- Weight calculator 160 may also include a weight selection unit
- echo-canceller 101 may adjust these values based on some predetermined condition.
- echo-canceller 101 may include a power monitor 170 arranged to monitor the value of power of signal Z(n) measured by periodic measurement unit 165. Based on the monitored value of the power, power monitor 170 may cause echo-canceller 101 to adjust the values of the weights (e.g., by selecting new values for the weights). For example, during a weight recalibration of echo-canceller 101 , power monitor 170 may cause periodic measurement unit 165 to measure the power of signal Z(n) after some predetermined time intervals or when wireless communication system 100 is not receiving signals (e.g., downlink signals).
- power monitor 170 may cause echo-canceller 101 to adjust the values of the weights so that the value of the power may be reduced to an appropriate value. This may allow the values of the weights to maintain optimum values (e.g., selected values) in order to maintain proper echo- cancellation operation performed by echo-canceller 101.
- a threshold value e.g., a predetermined value
- FIG. 2 is a flowchart showing a method 200 for operating a wireless communication system including an operation for selecting weighs to control attenuators of an echo-canceller according to some embodiments described herein.
- Method 200 may be performed by wireless communication system 100 of FIG. 1.
- the echo-canceller used in method 200 may include echo-canceller 101 of FIG. 1.
- the goal is searching for the value for each of the weights (e.g., wi through W6 FIG. 1) that yields a minimum value (e.g., local minimum) of the cost function of signal Z(n) (shown in FIG. 1).
- a minimum value of the cost function may be associated with weights where each of the weights may be a negative value or positive value (along the x-axis of the cost function C(W)).
- method 200 may start at activity 201 and perform activities 210 to 216 for searching for the sign
- method 200 may arrive at a starting value for each of the weights that is relatively closer to the global minimum value. This may allow the final value (the value that falls on a global minimum) of each of the weights to be found faster.
- method 200 may use the starting values of the weights in searching for a final value for each of the weights, as described in activities 220 to 228. Method 200 may end at activity 299 after the final values are found.
- attenuators e.g., attenuators 151, 152, and 153 in the echo estimation path of the echo-canceller are assumed to have a dynamic range in linear scale of w min - M - w max where Wmm corresponds to the minimum value of the dynamic range and w ma x corresponds to the maximum value of the dynamic range.
- Activities 212 to 216 may include performing an operation for determining the sign of each of the weights used to control the attenuators in the echo estimation path of the echo-canceller.
- the value of "K" in activity 212 may be equal to the number of the attenuators in the echo estimation path.
- Activity 213 may include calculating two values Ci(W) and
- the echo-canceller used in method 200 may measure the power of signal Z(n) at these two time intervals to calculate the values of Ci(W) and C 2 (W). During these measurements for a particular weight (e.g., wi in FIG. 1) the values for the other weights (e.g., W2 through w ) may remain unchanged.
- Activity 214 may include setting the value for a particular weight
- Method 200 may repeat the same operations (e.g., performing activities 213 through 216) for each of the weights (e.g., each of W2 through W6 in FIG. 1) until the sign (e.g., -w ,, - ⁇ /2 or Wmm + ⁇ /2) for each of the weights is determined (e.g., set).
- the sign e.g., -w ,, - ⁇ /2 or Wmm + ⁇ /2
- method 200 may continue with activities 220 to 228 to perform M iterations to further refine the value for each of the weights to search for a final value of each of the weights.
- activities 220 to 228 to perform M iterations to further refine the value for each of the weights to search for a final value of each of the weights.
- the value of Wk used in a particular iteration to calculate the value of the cost function is lower than a previous value (e.g., w3 ⁇ 4 0 w) of w3 ⁇ 4.
- a previous value e.g., w3 ⁇ 4 0 w
- the plurality of values are different from the values of the weight (e.g., Wmm + ⁇ /2 or Wmin - ⁇ /2) used for calculating and C 2 (W) in activities 213.
- Activities 221 through 228 may also include calculating a plurality of values of the cost function (e.g., calculating C ⁇ ⁇ W) and C 2 (W) in activities 223) when the plurality of values of the weights are applied. For each of the weights, the value of the cost function of signal Z(n) during a time interval associated with activities 220 through 228 is a lowest value (e.g., global minimum) among the plurality of values of the cost function of the signal Z(n).
- a lowest value e.g., global minimum
- Method 200 may repeat the same operations (e.g., performing activities 221 through 228) for each of the weights (e.g., each of w 2 through W6 in FIG. 1) until the final value (value that falls on a global minimum of the cost function) for each of the weights is determined (e.g., set).
- Method 200 may end at activity 299 after the final values of all of the weights are determined. Method 200 may select these values and apply them in the echo-canceller to control the attenuators of the echo-canceller.
- method 200 searches for the weights that fall on the global minimum and selects those values for use in the echo-canceller.
- optimum values for the weights e.g., that fall on the global minimum
- This may avoid an exhaustive search and avoid adaptively updating the weights. Avoiding such an exhaustive search and updating the weights may improve the speed for the search (e.g., faster search) for echo-canceller 101.
- the final values of the weight applied to the corresponding attenuators in the echo-canceller may be fixed.
- the final values of the weights may be adjusted (e.g., during a weight recalibration, as described above with reference to FIG. 1).
- method 200 may repeat activity 201 to 299 if a power monitor (e.g., power monitor 170 in FIG. 1) detects a change in the value of the power relative to a threshold value (e.g., a predetermined value).
- a threshold value e.g., a predetermined value
- method 200 may repeat activity 201 to 299 if the value of the power (e.g., during a weight calibration) is greater than threshold value.
- Method 200 may repeat activity 201 to 299 in during a time interval where no incoming signal is expected to be received by the wireless communication system. This is to avoid the incoming signal being used in the power calculation that may result in an inaccurate selection for the values of the weights.
- Method 200 may include fewer or more activities than the activities shown in FIG. 2.
- method 200 may also include or be included in operations of wireless communication system 100 described above with reference to FIG. 1 , a network station, or a wireless communication device described below with reference to FIG. 3 and FIG. 4.
- method 200 may perform an operation for calculating and selecting the values for the weights based on the cost function of signal Z(n) without using components associated with the transmitted signal x(t) (or x(n)) as inputs for calculating the values for the weights. Therefore, method 200 may be referred to as a blind technique for calculating the weights. Method 200 may allow the echo-canceller used in method 200 to be less complex, relatively faster, and less sensitive to RF impairments.
- FIG. 3 shows a wireless communication network 300 including a network station 302 and wireless communication devices 311 and 312, according to some embodiments described herein.
- Network station 302 may be arranged (e.g., configured) to wirelessly communicate with wireless communication device (WCD) 311 through a wireless connection 313 and with WCD 312 through a wireless connection 315.
- WCD wireless communication device
- Each of network station 302 and WCDs 111 and 112 may include wireless communication system 100 described above with reference to FIG. 1.
- each of network station 302 and WCDs 111 and 112 may include components and operations similar to, or identical to, those described above with reference to FIG. 1 and FIG. 2.
- each of network station 302 and WCDs 111 and 112 may include echo-canceller 101 of FIG. 1 and may be arranged to perform an echo-cancellation including an operation for calculating and selecting weights described above with reference to FIG. 1 and FIG. 2.
- an example of wireless communication network 300 includes an evolved universal terrestrial radio access network (EUTRAN) using the 3rd Generation Partnership Project (3 GPP) long term evolution (LTE) standards. Additional examples of wireless communication network 300 include Worldwide Interoperability for Microwave Access (WiMax) networks, 3rd generation (3G) networks, Wi-Fi networks, and other wireless data
- EUTRAN evolved universal terrestrial radio access network
- 3 GPP 3rd Generation Partnership Project
- LTE long term evolution
- Additional examples of wireless communication network 300 include Worldwide Interoperability for Microwave Access (WiMax) networks, 3rd generation (3G) networks, Wi-Fi networks, and other wireless data
- An example of network station 302 includes a base station (BS), an enhanced node B (eNB), an access point (AP), or another type of network station or network equipment.
- Network station 302 may be arranged to operate based on the 3GPP-LTE standards or other wireless data communication standards.
- Examples of WCDs 311 and 312 include user equipment (UE) and terminal equipment (e.g., data terminal equipment).
- user equipment and terminal equipment include cellular telephones (e.g., smartphones), tablet computers, e-readers (e.g., e-book readers), notebook computers, laptop computers, desktop computers, personal computers, servers, personal digital assistants (PDAs), digital cameras, medical devices (e.g., a heart rate monitor, a blood pressure monitor, etc.), televisions, web appliances, set-top boxes (STBs), network routers, network switches, network bridges, parking meters, sensors, and other types of devices and equipment.
- UE user equipment
- terminal equipment e.g., data terminal equipment
- user equipment and terminal equipment include cellular telephones (e.g., smartphones), tablet computers, e-readers (e.g., e-book readers), notebook computers, laptop computers, desktop computers, personal computers, servers, personal digital assistants (PDAs), digital cameras, medical devices (e.g., a heart rate
- WCDs 311 and 312 may be arranged (e.g., configured) to operate in different communication networks, such as a 3GPP-LTE network, a WiMax network, a wireless local area network (e.g., WiFi), and other communication networks.
- FIG. 3 shows wireless communication network 300 including only two WCDs (e.g., WCDs 311 and 312) to communicate with network station 302 as an example.
- Wireless communication network 300 may include more than two WCDs.
- Network station 302 may have a simultaneous transmit (Tx) and receive (Rx) capability (STR capability), such that it may operate in STR mode to simultaneously (e.g., concurrently) transmit and receive signals (e.g., radio- frequency (RF) signals).
- Network station 302 may include an RF transceiver that has a full-duplex capability to simultaneously transmit and receive signals. For example, network station 302 may transmit a downlink (DL) signal to WCD 311 while network station 302 receives an uplink (UL) signal from WCD 312. In another example, network station 302 may transmit a DL signal to WCD 312 while network station 302 receives a UL signal from WCD 311.
- DL downlink
- UL uplink
- FIG. 4 shows a block diagram of a WCD 400 including an echo- canceller 401, according to some embodiments described herein.
- WCD 400 may include components of wireless communication system 100 (FIG. 1). As shown in FIG. 4, WCD 400 may also include antennas 402 and 404, a transceiver 405 including a receiver 410 and transmitter 420, a controller 415, and a memory 430.
- Echo-canceller 401, receiver 410, and transmitter 420 may correspond to echo-canceller 101, receiver 110, and transmitter 120, respectively, of FIG. 1.
- echo-canceller 401, receiver 410, and transmitter 420 may be arranged to operate in ways similar to, or identical to, those of corresponding echo -canceller 101, receiver 110, and transmitter 120 of FIG. 1.
- WCD 400 in FIG. 4 may also include one or more of a keyboard, a display (e.g., an LCD screen including a touch screen), a non- volatile memory port (e.g., a Universal Serial Bus (USB) port), speakers, and other mobile device elements.
- a keyboard e.g., a keyboard
- a display e.g., an LCD screen including a touch screen
- a non- volatile memory port e.g., a Universal Serial Bus (USB) port
- Controller 415, echo-canceller 401, or both, may be arranged
- controller 415 and echo-canceller 401 may be arranged to perform an echo-cancellation operation including the operation for calculating and selecting weights as described above with reference to FIG. 1 and FIG. 2.
- Controller 415 may be arranged (e.g., configured) to provide processing and control functionalities for WCD 400, including at least part of the echo-cancellation operation described above with reference to FIG. 1 through FIG. 3.
- Controller 415 may include one or more processors that may include one or more central processing units (CPUs), one or more graphics processing units (GPUs), or a combination of one or more CPUs and one or more GPUs.
- CPUs central processing units
- GPUs graphics processing units
- Memory 430 may include volatile memory, non- volatile memory, or a combination of both.
- Memory 430 may store instructions (e.g., firmware programs, software programs, or a combination of both).
- Controller 415 may execute instructions in memory 430 to result in WCD 400 performing operations, such as echo-cancellation operation including the operation for selecting weights performed by wireless communication system 100 or method 200 described herein with reference to FIG. 1 through FIG. 2.
- Antennas 402 and 404 may include one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some embodiments, instead of two or more antennas, a single antenna with multiple apertures may be used. In these embodiments, each aperture may be considered a separate antenna.
- Antennas 402 and 404 may be arranged to support multiple-input and multiple- output (MIMO) communications. In some MIMO embodiments, antennas 402 and 404 may be effectively separated to benefit from spatial diversity and the different channel characteristics that may result between antennas 402 and 404 and the antennas of a transmitting station. In some MIMO embodiments, antennas 402 and 404 may be separated by up to 1/10 of a wavelength or more.
- FIG. 4 shows WCD 400 including one transceiver 405 and two antennas 402 and 404 as an example.
- the number of transceivers 405 and antennas 402, 404 may vary.
- Controller 415 and transceiver 405 may be arranged to operate in different communication networks, such as a 3GPP-LTE network, a WiMax network, wireless local area network (e.g., WiFi), and other communication networks.
- WCD 400 is shown as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements.
- DSPs digital signal processors
- some elements may comprise one or more microprocessors, DSPs, application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions and operations described herein.
- the functional elements may refer to one or more processes operating on one or more processing elements.
- Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions (e.g., firmware programs, software programs, or a combination of both) stored on a computer-readable storage medium, which may be read and executed by at least one processor to perform the operations described herein.
- a computer-readable storage medium may include any non-transitory mechanism (e.g., non-transitory computer-readable medium) for storing information (e.g., instructions) in a form readable by a machine (e.g., a computer).
- Examples of a computer-readable storage medium may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media.
- ROM read-only memory
- RAM random-access memory
- magnetic disk storage media magnetic disk storage media
- optical storage media magnetic disk storage media
- flash-memory devices and other storage devices and media.
- processors of the WCD 400 may be configured with the instructions to perform the operations described herein.
- Example 1 includes subject matter (such as a device, apparatus, or machine) including an echo-canceller for a wireless communication system, the echo-canceller comprising phase shifters to generate output signals, each of the phase shifters generating one of the output signals, each of the output signals having a phase shift relative to a transmitted signal, a attenuator unit (e.g., a variable or stepped attenuator unit) to attenuate the output signal of each of the phase shifters based on weights to generate attenuated signals, each of the attenuated signals corresponding to the output signal of one of the phase shifters, a weight calculator to perform an operation for selecting values for the weights without using components associated with the transmitted signal as inputs for calculating the values for the weights, and at least one summer to sum the attenuated signals and a received signal containing an echo signal to generate an echo-canceled signal.
- a attenuator unit e.g., a variable or stepped attenuator unit
- Example 2 the subject matter of Example 1 may optionally include, wherein the weight calculator is arranged to perform the operation for selecting the weights based at least in part on a cost function of a digital signal generated based on the echo-canceled signal.
- Example 3 the subject matter of Example 1 may optionally include, wherein the weight calculator is arranged to perform the operation for selecting the weights based the equation
- Z(n) represents the digital signal
- W represents a weight vector including the weights
- g represent a gain of a variable gain amplifier located on a path used to generate the digital signal.
- Example 4 the subject matter of Example 1 may optionally include, wherein the weight calculator is arranged to generate a signal based on the echo-canceled signal, calculate a first value of a cost function of the signal based on a first value of a weight applied to an attenuator (e.g., a variable or stepped attenuator) of the attenuator unit during a first time interval, calculate a second value of the cost function of the signal based on a second value of the weight applied to the attenuator unit during a second time interval, select a starting value of the weight to be equal to one of the first and second values of the weight, and perform an operation to search for a third value of the weight based on the starting value of the weight, such that when the third value of the weight is applied to the attenuator during a third time interval, a third value of the cost function of the signal during the third time interval is less than each of the first and second values of the cost function of the signal.
- the weight calculator is arranged to generate a signal based
- Example 5 the subject matter of Example 1 may optionally include, wherein the echo-canceller is included in a user equipment (UE).
- UE user equipment
- Example 6 the subject matter of Example 1 may optionally include, wherein the echo-canceller is included in one of a base station and an enhanced node B (eNB).
- eNB enhanced node B
- Example 7 includes subject matter including a wireless communication system comprising a receiver to receive a signal containing an echo signal, a transmitter to transmit a transmitted signal, and an echo-canceller comprising a first vector modulator to generate a first output signal from a sum of a first plurality of signals, the first plurality of signals being attenuated based on a first group of weights, each signal in the first plurality of signals having a phase shift relative to a first delayed version of the transmitted signal, a second vector modulator to generate a second output signal from a sum of a second plurality of signals, the second plurality of signals being attenuated based on a second group of weights, each signal in the second plurality of signals having a phase shift relative to a second delayed version of the transmitted signal, a summer to sum the first and second output signals and the received signal containing the echo signal to generate an echo-canceled signal, and a weight calculator arranged to perform an operation for selecting values for the first and second groups of weights based on a value
- Example 8 the subject matter of Example 7 may optionally include, wherein the echo-canceller further includes a power measurement unit to measure the power of the digital signal over a period of time to obtain the value of the power of the digital signal.
- Example 9 the subject matter of Example 8 may optionally include, wherein the echo-canceller further includes a variable gain amplifier to modify the echo-canceled signal, and an analog-to-digital converter to convert the echo-canceled signal after the echo-canceled signal is modified by the variable gain amplifier to generate the digital signal.
- the echo-canceller further includes a variable gain amplifier to modify the echo-canceled signal, and an analog-to-digital converter to convert the echo-canceled signal after the echo-canceled signal is modified by the variable gain amplifier to generate the digital signal.
- Example 10 the subject matter of Example 9 may optionally include, wherein the echo-canceller is arranged to compensate for the value of the power of the digital signal with a compensated value based on the gain of the variable gain amplifier.
- Example 11 the subject matter of Example 7 may optionally include, further comprising a power monitor to monitor a value of a power of the digital signal after the values for the first and second groups of weights are selected, and to cause the echo-canceller to perform an additional operation for adjusting the values for the first and second group of weights if the value of the power of the digital signal exceeds a threshold value.
- Example 12 the subject matter of Example 7 may optionally include, wherein the receiver and transmitter are included in a full-duplex transceiver of the wireless communication system.
- Example 13 the subject matter of Example 7 may optionally include, wherein the receiver is arranged to receive a downlink signal.
- Example 14 the subject matter of Example 7 may optionally include, wherein the receiver is arranged to receive an uplink signal.
- Example 15 includes subject matter including a method of operating a wireless communication system, the method comprising calculating a first value of a cost function of the signal based on a first value of a weight applied in the echo-canceller during a first time interval, calculating a second value of the cost function of the signal based on a second value of the weight applied in the echo-canceller during a second time interval, selecting a starting value of the weight to be equal to one of the first and second values of the weight, and performing an operation to search for a third value of the weight based on the starting value of the weight, such that when the third value of the weight is applied in the echo-canceller during a third time interval, a third value of the cost function of the signal during the third time interval is less than each of the first and second values of the cost function of the signal.
- Example 16 the subject matter of Example 15 may optionally include, wherein selecting the starting value of the weight includes selecting the starting value of the weight to be equal to the first value of the weight if the first value of the cost function of the signal is less than the second value of the cost function of the signal, and selecting the starting value of the weight to be equal to the second value of the weight if the first value of the cost function of the signal is greater than the second value of the cost function of the signal.
- Example 17 the subject matter of Example 15 may optionally include, wherein the cost function of the signal is
- Z(n) represents the signal based on the output signal
- W represents a weight vector including the weight
- g represents a gain of a variable gain amplifier located on a path used to generate the signal.
- attenuators e.g., variable or stepped attenuators
- Example 19 the subject matter of Example 15 may optionally include, wherein the third value of the weight falls on a global minimum of the cost function of the signal.
- Example 20 the subject matter of Example 15 may optionally include, wherein performing the operation to search for the third value of weight includes applying a plurality of values of the weights to control attenuators (e.g., variable or stepped attenuators) of the echo-canceller, wherein the plurality of values are different from the first and second values of the weight, and calculating a plurality of values of the cost function when the plurality of values of the weight are applied, wherein the value of the cost function of the signal during the third time interval is a lowest value among the plurality of values of the cost function of the signal.
- control attenuators e.g., variable or stepped attenuators
- Example 21 the subject matter of Example 15 may optionally include, further comprising calculating a third value of the cost function of the signal based on a first value of an additional weight applied in the echo-canceller during a fourth time interval, wherein the fourth time interval occurs after the first and second time intervals and before the third time interval, calculating a fourth value of the cost function of the signal based on a second value of the additional weight applied in echo-canceller during a fifth time interval, wherein the fifth time interval occurs after the first and second time intervals and before the third time interval, selecting a starting value of the additional weight to be equal to first value of the additional weight if the third value of the cost function is less than the fourth value of the cost function, selecting the starting value of the additional weight to be equal to the second value of the additional weight if the third value of the cost function is greater than the fourth value of the cost function, and performing an operation to search for a third value of the additional weight, such that when the third value of the additional weight is applied in echo-cancell
- Example 22 the subject matter of Example 15 may optionally include, wherein selecting the starting value of the additional weight includes selecting the starting value of the additional weight to be equal to first value of the additional weight if the third value of the cost function is less than the fourth value of the cost function, and selecting the starting value of the additional weight to be equal to the second value of the additional weight if the third value of the cost function is greater than the fourth value of the cost function
- Example 23 includes subject matter including a computer- readable storage medium for storing information, which when executed, causes a wireless communication device to generate a signal based on an output signal from an echo-canceller, calculate a first value of a cost function of the signal based on a first value of a weight applied in the echo-canceller during a first time interval, calculate a second value of the cost function of the signal based on a second value of the weight applied in the echo-canceller during a second time interval, select a starting value of the weight to be equal to one of the first and second values of the weight, and perform an operation to search for a third value of the weight based on the starting value of the weight, such that when the third value of the weight is applied in the echo-canceller during a third time interval, a third value of the cost function of the signal during the third time interval is less than each of the first and second values of the cost function of the signal
- Example 24 the subject matter of Example 23 may optionally include, wherein the starting value of the weight is selected to be equal to the first value of the weight if the first value of the cost function of the signal is less than the second value of the cost function of the signal, and the starting value of the weight is selected to be equal to the second value of the weight if the first value of the cost function of the signal is greater than the second value of the cost function of the signal.
- Example 25 the subject matter of Example 23 may optionally include, wherein the cost function of the signal is
- Z(n) represents the signal based on the output signal
- W represents a weight vector including the weight
- g represent a gain of a variable gain amplifier located on a path used to generate the signal.
- Example 25 The subject matter of Examples 1 through Example 25 may be combined in any combination.
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PCT/US2014/039404 WO2015178932A1 (en) | 2014-05-23 | 2014-05-23 | Blind technique for weight selection in simultaneous transmit and receive structure |
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EP (1) | EP3146646A4 (en) |
CN (1) | CN106233638B (en) |
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US4707824A (en) * | 1983-12-15 | 1987-11-17 | Nec Corporation | Method and apparatus for cancelling echo |
US5793801A (en) * | 1996-07-09 | 1998-08-11 | Telefonaktiebolaget Lm Ericsson | Frequency domain signal reconstruction compensating for phase adjustments to a sampling signal |
US6751264B2 (en) * | 2001-07-27 | 2004-06-15 | Motorola, Inc. | Receiver and method therefor |
US8279783B1 (en) * | 2005-08-12 | 2012-10-02 | Aquantia Corporation | Linear-equivalent echo and next cancellers for Tomlinson-Harashima Precoding (THP) systems |
US7916671B1 (en) * | 2009-07-16 | 2011-03-29 | Pmc-Sierra, Inc. | Echo cancellation for duplex radios |
US8553814B2 (en) * | 2009-07-31 | 2013-10-08 | Lsi Corporation | Rapid sampling phase recovery |
JP2011205533A (en) * | 2010-03-26 | 2011-10-13 | Mitsubishi Electric Corp | Adaptive equalizer, echo canceler and active noise control apparatus |
CN102044253B (en) * | 2010-10-29 | 2012-05-30 | 深圳创维-Rgb电子有限公司 | Echo signal processing method and system as well as television |
WO2013095386A1 (en) * | 2011-12-20 | 2013-06-27 | Intel Corporation | Techniques to simultaneously transmit and receive over the same radio-frequency carrier |
US9231561B2 (en) * | 2011-12-30 | 2016-01-05 | Intel Corporation | Multi-stage adaptive filter |
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TW201545519A (en) | 2015-12-01 |
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