US20160112134A1 - Wireless communication system, baseband processing device, and wireless device - Google Patents
Wireless communication system, baseband processing device, and wireless device Download PDFInfo
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- US20160112134A1 US20160112134A1 US14/827,040 US201514827040A US2016112134A1 US 20160112134 A1 US20160112134 A1 US 20160112134A1 US 201514827040 A US201514827040 A US 201514827040A US 2016112134 A1 US2016112134 A1 US 2016112134A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
- H04B10/25752—Optical arrangements for wireless networks
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0799—Monitoring line transmitter or line receiver equipment
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
- H04B10/25752—Optical arrangements for wireless networks
- H04B10/25753—Distribution optical network, e.g. between a base station and a plurality of remote units
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
- H04B10/505—Laser transmitters using external modulation
- H04B10/5057—Laser transmitters using external modulation using a feedback signal generated by analysing the optical output
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/69—Electrical arrangements in the receiver
- H04B10/697—Arrangements for reducing noise and distortion
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B2210/00—Indexing scheme relating to optical transmission systems
- H04B2210/25—Distortion or dispersion compensation
- H04B2210/254—Distortion or dispersion compensation before the transmission line, i.e. pre-compensation
Definitions
- the embodiments discussed herein are related to a wireless communication system, a baseband processing device, and a wireless device.
- wireless base station devices (hereinafter, often referred to simply as the “base station”) are provided with an amplifying unit that amplifies the power of a transmission signal.
- the amplifying unit is operated near the saturation region of the amplifying unit in order to enhance the power efficiency of the amplifying unit.
- the base station is provided with a distortion compensating unit that compensates for the non-linear distortion.
- the distortion compensating unit of the PD system enhances the linearity of the output of the amplifying unit and suppresses the distortion of the output of the amplifying unit by multiplying a transmission baseband signal before input to the amplifying unit by a distortion compensation coefficient having the inverse characteristic of the non-linear distortion of the amplifying unit in advance.
- the signal resulting from the multiplication of the transmission baseband signal by the distortion compensation coefficient is often referred to as the “PD signal.”
- the PD signal is a signal that gets distorted in advance before input to the amplifying unit in accordance with the inverse characteristic of the non-linear distortion of the amplifying unit.
- the distortion compensating unit of the PD system there is one that includes a lookup table (LUT) in which plural distortion compensation coefficients are stored and specifies, to the LUT, an address according to the power of the transmission baseband signal to read out the distortion compensation coefficient from the LUT.
- the distortion compensation coefficients stored in the LUT are sequentially updated so that the error between the transmission baseband signal as a reference signal and a signal that is output from the amplifying unit and is fed back (hereinafter, often referred to as the “feedback signal”), obtained by comparing both signals, may be minimized.
- the feedback signal a signal that is output from the amplifying unit and is fed back
- a wireless communication system includes a baseband processing device configured to transmit a data signal via an optical transmission line, and a wireless device configured to receive the data signal via the optical transmission line and carry out wireless transmission of an output signal obtained by amplifying the data signal, wherein the wireless device includes a radio frequency circuit configured to amplify the data signal to generate the output signal, a first memory, and a first processor coupled to the first memory and configured to generate a feedback signal according to the output signal generated by the radio frequency circuit, and transmit the feedback signal to the baseband processing device via the optical transmission line, and wherein the baseband processing device includes a second memory, and a second processor coupled to the second memory and configured to acquire the feedback signal from the wireless device, and execute first processing of multiplying the data signal by a distortion compensation coefficient corresponding to an inverse characteristic of distortion in the radio frequency circuit based on the feedback signal.
- FIG. 1 is a block diagram illustrating one example of a wireless communication system of a first embodiment
- FIG. 2 is a block diagram illustrating one example of a baseband processing device of the first embodiment
- FIG. 3 is a block diagram illustrating one example of a distortion compensating unit of the first embodiment
- FIG. 4 is a block diagram illustrating one example of a wireless device of the first embodiment
- FIG. 5 is a block diagram illustrating one example of a baseband processing device of a second embodiment
- FIG. 6 is a block diagram illustrating one example of a wireless device of the second embodiment
- FIG. 7 is a flowchart illustrating one example of a processing operation of a baseband processing device of the second embodiment
- FIG. 8 is a flowchart illustrating one example of a processing operation of a wireless device of the second embodiment
- FIG. 9 is a block diagram illustrating one example of a baseband processing device of a third embodiment.
- FIG. 10 is a block diagram illustrating one example of a wireless device of the third embodiment.
- FIG. 11 is a flowchart illustrating one example of a processing operation of a baseband processing device of the third embodiment
- FIG. 12 is a block diagram illustrating one example of a baseband processing device of a fourth embodiment
- FIG. 13 is a block diagram illustrating one example of a wireless device of the fourth embodiment.
- FIG. 14 is a flowchart illustrating one example of a processing operation of a baseband processing device of the fourth embodiment
- FIG. 15 is a diagram illustrating a hardware configuration example of a baseband processing device.
- FIG. 16 is a diagram illustrating a hardware configuration example of a wireless device.
- the transmission capacity will be often referred to as the “system capacity”).
- system capacity For example, in the 3rd generation partnership project long term evolution (3GPP LTE), discussion relating to techniques for increasing the system capacity by utilizing “small cells” besides “macrocells” is being made.
- the “cell” is prescribed on the basis of the “cover area” and the “channel frequency” of one base station device (hereinafter, often referred to simply as the “base station”).
- the “cover area” may be the whole of the area to which radio waves transmitted from the base station reach or may be a divided area (so-called sector) obtained by dividing the reach area.
- the “channel frequency” is one unit of the frequency used by the base station for communications and is prescribed on the basis of the center frequency and the bandwidth. Furthermore, the channel frequency is part of the “operating band” allocated to the whole system.
- the “macrocell” is the cell of a base station capable of transmission with high transmission power, i.e. a base station having a large cover area.
- the “small cell” is the cell of a base station that carries out transmission with low transmission power, i.e. a base station having a small cover area.
- BBU baseband unit
- RRH remote radio head
- the disclosed techniques are made in view of the above and intend to provide a baseband processing device, a wireless device, and a wireless communication system that allow size reduction of the wireless device.
- Embodiments of a baseband processing device, a wireless device, and a wireless communication system disclosed by the present application will be described in detail below on the basis of the drawings.
- the baseband processing device, the wireless device, and the wireless communication system disclosed by the present application are not limited by the embodiments. Furthermore, a configuration having the same function in the embodiments is given the same symbol and overlapping description is omitted.
- FIG. 1 is a block diagram illustrating one example of a wireless communication system of a first embodiment.
- a wireless communication system 1 includes a baseband processing device 10 , a wireless device 50 , and a terminal 90 .
- the baseband processing device 10 and the wireless device 50 are coupled to each other by an optical transmission line L 1 .
- the baseband processing device 10 and the wireless device 50 are included in a base station.
- the wireless device 50 and the terminal 90 are wirelessly coupled to each other.
- the numbers of baseband processing devices 10 , wireless devices 50 , and terminals 90 are each set to one in FIG. 1 , the numbers of them are not limited thereto.
- the wireless device 50 receives a transmission-object data signal that is transmitted by the baseband processing device 10 and is to be delivered to the terminal 90 via the optical transmission line L 1 .
- the wireless device 50 amplifies the received data signal by an amplifying unit to be described later and then carries out wireless transmission of the resulting data signal to the terminal 90 .
- the wireless device 50 forms a “feedback signal” according to an output signal of the amplifying unit and transmits the formed feedback signal to the baseband processing device 10 via the optical transmission line L 1 .
- the baseband processing device 10 acquires the feedback signal transmitted from the wireless device 50 and executes “distortion compensation processing” on the basis of the acquired feedback signal.
- the “distortion compensation processing” is processing of multiplying a transmission-object data signal by a distortion compensation coefficient corresponding to the inverse characteristic of distortion in the amplifying unit.
- a distortion compensating unit that compensates for the distortion in the amplifying unit of the wireless device 50 is provided not in the wireless device 50 but in the baseband processing device 10 . This can realize size reduction and power saving of the wireless device 50 .
- FIG. 2 is a block diagram illustrating one example of a baseband processing device of the first embodiment.
- the baseband processing device in FIG. 2 may be the baseband processing device 10 illustrated in FIG. 1 .
- the baseband processing device 10 includes a baseband unit 11 , a distortion compensating unit 12 , a high-speed serial interface unit 13 , an optical interface unit 14 , and an extracting unit 15 .
- the high-speed serial interface unit 13 includes a multiplexer 21 and a demultiplexer 22 .
- the optical interface unit 14 includes an electrical/optical converter 23 and an optical/electrical converter 24 .
- the baseband unit 11 generates a transmission baseband signal by executing baseband processing such as coding processing and modulation processing for input transmission data, and outputs the generated transmission baseband signal In(t) to the distortion compensating unit 12 .
- the distortion compensating unit 12 is a distortion compensating unit of the PD system and includes a LUT in which plural distortion compensation coefficients each corresponding to a respective one of plural addresses corresponding to plural power ranges are stored.
- the distortion compensating unit 12 generates a PD signal Out(t) by multiplying the transmission baseband signal by the distortion compensation coefficient read out from the LUT through reference to the LUT in accordance with an address generated according to the power of the transmission baseband signal.
- the distortion compensating unit 12 outputs the generated PD signal Out(t) to the high-speed serial interface unit 13 .
- the distortion compensating unit 12 updates the distortion compensation coefficients stored in the LUT on the basis of the error between the transmission baseband signal In(t) as a reference signal and a feedback signal FB(t).
- FIG. 3 is a block diagram illustrating one example of a distortion compensating unit of the first embodiment.
- the distortion compensating unit in FIG. 3 may be the distortion compensating unit 12 illustrated in FIG. 2 .
- the distortion compensating unit 12 includes an address calculator 31 , a LUT 32 , a multiplier 33 , delay sections 34 , 35 , and 36 , a comparator 37 , and a compensation coefficient calculator 38 .
- the address calculator 31 calculates an address on the basis of the power value and phase of the transmission baseband signal In(t).
- the LUT 32 reads out the distortion compensation coefficient corresponding to an address Adr(t) calculated in the address calculator 31 from a distortion compensation coefficient table and outputs the read distortion compensation coefficient to the multiplier 33 and the delay section 35 . Furthermore, the LUT 32 updates the distortion compensation coefficient table by using an update value of the distortion compensation coefficient calculated in the compensation coefficient calculator 38 and an update address received from the delay section 34 .
- the LUT 32 includes an updating section 41 , a table storing section 42 , and a reading section 43 as illustrated in FIG. 3 .
- the updating section 41 executes update processing of updating the distortion compensation coefficient table by using the update value of the distortion compensation coefficient calculated in the compensation coefficient calculator 38 and the update address received from the delay section 34 .
- the table storing section 42 stores the “distortion compensation coefficient table” in which plural distortion compensation coefficients each corresponding to a respective one of plural address values are stored.
- the reading section 43 reads out the distortion compensation coefficient corresponding to the address Adr(t) calculated in the address calculator 31 from the distortion compensation coefficient table and outputs the read distortion compensation coefficient to the multiplier 33 and the delay section 35 .
- the multiplier 33 multiplies the transmission baseband signal In(t) and the distortion compensation coefficient from the LUT 32 and outputs the transmission baseband signal In(t) resulting from the distortion compensation processing, i.e. the PD signal Out(t), to the high-speed serial interface unit 13 .
- the delay section 34 delays the address Adr(t) by the amount d 1 of delay and outputs the delayed address Adr(t) to the updating section 41 as the update address.
- the amount d 1 of delay corresponds to the total delay time taken until the transmission baseband signal In(t) is transmitted to the wireless device 50 and the update value of the distortion compensation coefficient is calculated on the basis of the feedback signal FB(t) transmitted from the wireless device 50 in response to the transmission baseband signal In(t).
- the delay section 35 delays the distortion compensation coefficient output from the LUT 32 by the amount d 2 of delay and outputs the delayed distortion compensation coefficient to the compensation coefficient calculator 38 .
- the amount d 2 of delay corresponds to the total delay time taken until the transmission baseband signal In(t) is transmitted to the wireless device 50 and the difference between the feedback signal FB(t) transmitted from the wireless device 50 in response to the transmission baseband signal In(t) and the transmission baseband signal In(t) is calculated.
- the delay section 36 delays the transmission baseband signal In(t) as the reference signal by the amount d 3 of delay and outputs the delayed reference signal to the comparator 37 .
- the amount d 3 of delay corresponds to the total delay time taken until the transmission baseband signal In(t) is transmitted to the wireless device 50 and the feedback signal FB(t) transmitted from the wireless device 50 in response to the transmission baseband signal In(t) is input to the comparator 37 .
- the comparator 37 compares the transmission baseband signal In(t) as the reference signal with the feedback signal FB(t) to calculate an error signal e(t) of both signals and output the calculated error signal e(t) to the compensation coefficient calculator 38 .
- the compensation coefficient calculator 38 calculates the update value of the distortion compensation coefficient on the basis of the error signal e(t) received from the comparator 37 and the distortion compensation coefficient received via the delay section 35 , and outputs the calculated update value of the distortion compensation coefficient to the updating section 41 .
- the high-speed serial interface unit 13 is compliant with the JEDEC standards (JESD), which is a serial interface standard, for example.
- the high-speed serial interface unit 13 multiplexes (superimposes) a clock (i.e. timing information) on the transmission baseband signal In(t) resulting from the distortion compensation processing and outputs the multiple signal to the optical interface unit 14 .
- the high-speed serial interface unit 13 demultiplexes a multiple signal received from the optical interface unit 14 into a clock and a signal other than the clock.
- the high-speed serial interface unit 13 includes the multiplexer 21 and the demultiplexer 22 .
- the above-described multiplexing processing is executed in the multiplexer 21 and the above-described demultiplexing processing is executed in the demultiplexer 22 .
- the optical interface unit 14 includes the electrical/optical converter 23 and the optical/electrical converter 24 .
- the electrical/optical converter 23 converts the multiple signal received from the high-speed serial interface unit 13 from an electrical signal to an optical signal and sends out the obtained optical signal to the optical transmission line L 1 .
- the sent optical signal is transmitted to the wireless device 50 .
- the optical/electrical converter 24 receives an optical signal transmitted from the wireless device 50 and converts the received optical signal to an electrical signal to output the obtained electrical signal, i.e. a received electrical signal, to the demultiplexer 22 .
- the extracting unit 15 extracts the feedback signal FB(t) from the signal other than the clock, obtained in the demultiplexer 22 , and outputs the extracted feedback signal FB(t) to the distortion compensating unit 12 .
- FIG. 4 is a block diagram illustrating one example of a wireless device of the first embodiment.
- the wireless device in FIG. 4 may be the wireless device 50 illustrated in FIG. 1 .
- the wireless device 50 includes an optical interface unit 51 , a high-speed serial interface unit 52 , an extracting unit 53 , a wireless transmission unit 54 , a coupler 55 , a down-converter 56 , an analog-digital (A/D) converter 57 , a circulator 58 , and a wireless reception unit 59 .
- A/D analog-digital
- the optical interface unit 51 includes an optical/electrical converter 61 and an electrical/optical converter 62 .
- the optical/electrical converter 61 receives an optical signal transmitted from the baseband processing device 10 and converts the received optical signal to an electrical signal to output the obtained electrical signal (i.e. received electrical signal) to the high-speed serial interface unit 52 .
- the electrical/optical converter 62 converts a multiple signal received from the high-speed serial interface unit 52 from an electrical signal to an optical signal and sends out the obtained optical signal to the optical transmission line L 1 .
- the sent optical signal is transmitted to the baseband processing device 10 .
- the high-speed serial interface unit 52 is compliant with the JESD standard, which is a serial interface standard, for example.
- the high-speed serial interface unit 52 demultiplexes the received electrical signal received from the optical/electrical converter 61 into a clock and a signal other than the clock.
- the high-speed serial interface unit 52 multiplexes (superimposes) a clock, i.e. timing information, on a feedback signal received from the A/D converter 57 and a received signal received from the wireless reception unit 59 and outputs the multiple signal to the optical interface unit 51 .
- the high-speed serial interface unit 52 includes a demultiplexer 63 and a multiplexer 64 .
- the above-described multiplexing processing is executed in the multiplexer 64 and the above-described demultiplexing processing is executed in the demultiplexer 63 .
- the extracting unit 53 extracts a data signal from the signal other than the clock, obtained in the demultiplexer 63 , and outputs the extracted data signal to the wireless transmission unit 54 .
- the wireless transmission unit 54 executes given wireless processing, for example, digital-analog conversion, up-conversion, amplification, and so forth, on the data signal extracted in the extracting unit 53 and outputs the obtained wireless signal to the coupler 55 .
- the wireless transmission unit 54 includes a digital-analog (D/A) converter 65 , an up-converter 66 , and an amplifying section 67 as illustrated in FIG. 4 .
- the above-described digital-analog conversion processing is executed in the D/A converter 65 .
- the above-described up-conversion processing is executed in the up-converter 66 .
- the above-described amplification processing is executed in the amplifying section 67 .
- the coupler 55 distributes the wireless signal output from the wireless transmission unit 54 to the circulator 58 and the down-converter 56 . Thereby, the output signal of the amplifying section 67 is fed back to the baseband processing device 10 via the down-converter 56 and the A/D converter 57 .
- the down-converter 56 carries out down-conversion of the signal input from the coupler 55 and outputs the down-converted signal to the A/D converter 57 .
- the A/D converter 57 converts the down-converted signal from an analog signal to a digital signal and outputs the digital signal resulting from the conversion to the multiplexer 64 as the feedback signal FB(t).
- the circulator 58 transmits the wireless signal output from the coupler 55 via an antenna. Furthermore, the circulator 58 outputs a signal received via the antenna to the wireless reception unit 59 .
- the wireless reception unit 59 executes given wireless reception processing, for example, down-conversion, analog-digital conversion, and so forth, on the wireless signal received from the circulator 58 and outputs the obtained received signal to the multiplexer 64 .
- the baseband processing device 10 includes the distortion compensating unit 12 that compensates for distortion in the amplifying section 67 of the wireless device 50 .
- This configuration of the baseband processing device 10 can remove the distortion compensating unit from the wireless device 50 and thus realize size reduction of the wireless device 50 .
- the down-converter 56 and the A/D converter 57 as a forming unit of the feedback signal form a feedback signal according to the output signal of the amplifying section 67
- the high-speed serial interface unit 52 and the optical interface unit 51 as a transmitting unit transmit the feedback signal to the baseband processing device 10 via the optical transmission line L 1 .
- This configuration of the wireless device 50 allows the distortion compensation processing to be executed in the baseband processing device 10 . As a result, size reduction of the wireless device 50 can be realized.
- a second embodiment relates to frame synchronization processing between a baseband processing device and a wireless device.
- FIG. 5 is a block diagram illustrating one example of a baseband processing device of the second embodiment.
- a configuration relating to the frame synchronization processing is illustrated in addition to the configuration of the baseband processing device 10 illustrated in FIG. 2 .
- the baseband processing device 10 includes a link-up controller 111 , reference clock generators 112 and 115 , a frame correction controller 113 , frame pulse generators 114 and 116 , and a frame correcting unit 117 .
- the reference clock generators 112 and 115 are described as different functional units. However, the reference clock generators 112 and 115 are not limited thereto and may be implemented by one functional unit. Similarly, the frame pulse generators 114 and 116 may also be implemented by one functional unit.
- the link-up controller 111 controls link-up of the downlink line, i.e. the line of the direction from the baseband processing device 10 to a wireless device 50 .
- the link-up controller 111 outputs a K code to the multiplexer 21 in a link-up procedure. A clock is multiplexed on this K code and the resulting K code is transmitted to the wireless device 50 .
- the link-up controller 111 outputs an output command of a “start trigger pulse” to the reference clock generator 112 after the elapse of a given time from the start of the link-up procedure.
- the “start trigger pulse” is output from the reference clock generator 112 to the frame pulse generator 114 , and the frame pulse generator 114 outputs a frame pulse to the multiplexer 21 every frame.
- the “start trigger pulse” is e.g. a one-pulse signal.
- the link-up controller 111 receives a “link-up request signal” from the frame pulse generator 114 and outputs an initial lane alignment sequence (ILAS) pattern to the multiplexer 21 in response to this “link-up request signal.”
- ILAS initial lane alignment sequence
- a clock is multiplexed on this ILAS pattern and the resulting ILAS pattern is transmitted to the wireless device 50 .
- the link-up controller 111 outputs a “correction control start command” to the frame correction controller 113 .
- the reference clock generator 112 When receiving the output command of the “start trigger pulse” from the link-up controller 111 , the reference clock generator 112 outputs the “start trigger pulse” to the frame pulse generator 114 .
- the frame pulse generator 114 When receiving the “start trigger pulse” from the reference clock generator 112 , the frame pulse generator 114 starts the output of the frame pulse.
- the frame pulse generator 114 includes a counter and outputs the frame pulse to the multiplexer 21 every time the count value of the counter becomes the value corresponding to one frame. Furthermore, when starting the output of the frame pulse, the frame pulse generator 114 outputs the above-described “link-up request signal” to the link-up controller 111 .
- the frame correction controller 113 When receiving the “correction control start command” from the link-up controller 111 , the frame correction controller 113 acquires the count value at the timing from the frame pulse generator 114 and outputs a control data signal including the acquired count value to the multiplexer 21 . This control data signal is transmitted to the wireless device 50 .
- the reference clock generator 115 When receiving a clock obtained by being demultiplexed from a multiple signal in the demultiplexer 22 , the reference clock generator 115 outputs a “start trigger pulse” to the frame pulse generator 116 .
- the frame pulse generator 116 When receiving the “start trigger pulse” from the reference clock generator 115 , the frame pulse generator 116 starts output of a frame pulse.
- the frame pulse generator 116 includes a counter and outputs the frame pulse to the demultiplexer 22 every time the count value of the counter becomes the value corresponding to one frame.
- the frame correcting unit 117 When receiving a control data signal that is transmitted from the wireless device 50 and is extracted in the extracting unit 15 , the frame correcting unit 117 acquires the count value at the timing from the frame pulse generator 116 . Then, the frame correcting unit 117 calculates a correction value to correct the count value of the frame pulse generator 116 on the basis of the count value of the wireless device 50 included in the control data signal. Then, the frame correcting unit 117 corrects the count value of the frame pulse generator 116 by the calculated correction value. For example, the frame correcting unit 117 calculates the correction value by subtracting the count value of the wireless device 50 included in the control data signal from the count value of the frame pulse generator 116 .
- FIG. 6 is a block diagram illustrating one example of a wireless device of the second embodiment.
- a configuration relating to the frame synchronization processing is illustrated in addition to the configuration of the wireless device 50 illustrated in FIG. 4 .
- the processing operation of functional units relating to the frame synchronization processing of the wireless device 50 of the second embodiment is basically the same as the processing operation of functional units relating to the frame synchronization processing of the above-described baseband processing device 10 of the second embodiment.
- the wireless device 50 includes a link-up controller 151 , reference clock generators 152 and 155 , a frame correction controller 153 , frame pulse generators 154 and 156 , and a frame correcting unit 157 .
- the reference clock generators 152 and 155 are described as different functional units. However, the reference clock generators 152 and 155 are not limited thereto and may be implemented by one functional unit. Similarly, the frame pulse generators 154 and 156 may also be implemented by one functional unit.
- the link-up controller 151 controls link-up of the uplink line, i.e. the line of the direction from the wireless device 50 to the baseband processing device 10 .
- the link-up controller 151 outputs a K code to the multiplexer 64 in a link-up procedure. A clock is multiplexed on this K code and the resulting K code is transmitted to the baseband processing device 10 .
- the link-up controller 151 outputs an output command of a “start trigger pulse” to the reference clock generator 152 after the elapse of a given time from the start of the link-up procedure.
- the “start trigger pulse” is output from the reference clock generator 152 to the frame pulse generator 154 , and the frame pulse generator 154 outputs a frame pulse to the multiplexer 64 every frame.
- the “start trigger pulse” is e.g. a one-pulse signal.
- the link-up controller 151 receives a “link-up request signal” from the frame pulse generator 154 and outputs an ILAS pattern to the multiplexer 64 in response to this “link-up request signal.” A clock is multiplexed on this ILAS pattern and the resulting ILAS pattern is transmitted to the baseband processing device 10 .
- the link-up controller 151 outputs a “correction control start command” to the frame correction controller 153 .
- the reference clock generator 152 When receiving the output command of the “start trigger pulse” from the link-up controller 151 , the reference clock generator 152 outputs the “start trigger pulse” to the frame pulse generator 154 .
- the frame pulse generator 154 When receiving the “start trigger pulse” from the reference clock generator 152 , the frame pulse generator 154 starts the output of the frame pulse.
- the frame pulse generator 154 includes a counter and outputs the frame pulse to the multiplexer 64 every time the count value of the counter becomes the value corresponding to one frame. Furthermore, when starting the output of the frame pulse, the frame pulse generator 154 outputs the above-described “link-up request signal” to the link-up controller 151 .
- the frame correction controller 153 When receiving the “correction control start command” from the link-up controller 151 , the frame correction controller 153 acquires the count value at the timing from the frame pulse generator 154 and outputs a control data signal including the acquired count value to the multiplexer 64 . This control data signal is transmitted to the baseband processing device 10 .
- the reference clock generator 155 When receiving a clock obtained by being demultiplexed from a multiple signal in the demultiplexer 63 , the reference clock generator 155 outputs a “start trigger pulse” to the frame pulse generator 156 .
- the frame pulse generator 156 When receiving the “start trigger pulse” from the reference clock generator 155 , the frame pulse generator 156 starts output of a frame pulse.
- the frame pulse generator 156 includes a counter and outputs the frame pulse to the demultiplexer 63 every time the count value of the counter becomes the value corresponding to one frame.
- the frame correcting unit 157 When receiving a control data signal that is transmitted from the baseband processing device 10 and is extracted in the extracting unit 53 , the frame correcting unit 157 acquires the count value at the timing from the frame pulse generator 156 . Then, the frame correcting unit 157 calculates a correction value to correct the count value of the frame pulse generator 156 on the basis of the count value of the baseband processing device 10 included in the control data signal. Then, the frame correcting unit 157 corrects the count value of the frame pulse generator 156 by the calculated correction value. For example, the frame correcting unit 157 calculates the correction value by subtracting the count value of the baseband processing device 10 included in the control data signal from the count value of the frame pulse generator 156 .
- FIG. 7 is a flowchart illustrating one example of a processing operation of a baseband processing device of the second embodiment.
- the baseband processing device performing the processing operation in FIG. 7 may be the baseband processing device 10 illustrated in FIG. 5 .
- the link-up controller 111 outputs a K code to the multiplexer 21 (step S 101 ).
- the reference clock generator 112 outputs a “start trigger pulse” to the frame pulse generator 114 (step S 102 ).
- the reference clock generator 112 outputs the “start trigger pulse” when receiving an output command of the “start trigger pulse” from the link-up controller 111 .
- the link-up controller 111 outputs the output command of the “start trigger pulse” to the reference clock generator 112 after the elapse of a given time from the start of a link-up procedure.
- the frame pulse generator 114 When receiving the “start trigger pulse” from the reference clock generator 112 , the frame pulse generator 114 starts output of a frame pulse (step S 103 ).
- the frame pulse generator 114 When starting the output of the frame pulse, the frame pulse generator 114 outputs a “link-up request signal” to the link-up controller 111 (step S 104 ).
- the link-up controller 111 When receiving the “link-up request signal” from the frame pulse generator 114 , the link-up controller 111 transmits an ILAS pattern to the wireless device 50 (step S 105 ).
- the link-up controller 111 After outputting the ILAS pattern, the link-up controller 111 outputs a “correction control start command” to the frame correction controller 113 (step S 106 ).
- the frame correction controller 113 acquires a count value at the timing from the frame pulse generator 114 (step S 107 ).
- the frame correction controller 113 transmits a control data signal including the acquired count value to the wireless device 50 (step S 108 ).
- FIG. 8 is a flowchart illustrating one example of a processing operation of a wireless device of the second embodiment.
- the wireless device performing the processing operation in FIG. 8 may be the wireless device 50 illustrated in FIG. 6 .
- the reference clock generator 155 acquires a clock obtained by being demultiplexed from a multiple signal in the demultiplexer 63 (step S 201 ).
- the reference clock generator 155 When receiving the clock obtained by being demultiplexed from the multiple signal in the demultiplexer 63 , the reference clock generator 155 outputs a “start trigger pulse” to the frame pulse generator 156 (step S 202 ).
- the frame pulse generator 156 When receiving the “start trigger pulse” from the reference clock generator 155 , the frame pulse generator 156 starts output of a frame pulse (step S 203 ).
- the frame correcting unit 157 acquires a control data signal (including a count value) that is transmitted from the baseband processing device 10 and is extracted in the extracting unit 53 (step S 204 ).
- the frame correcting unit 157 acquires a count value at the timing from the frame pulse generator 156 (step S 205 ).
- the frame correcting unit 157 executes correction processing on the basis of the count value of the baseband processing device 10 included in the control data signal and the count value of the frame pulse generator 156 (step S 206 ). That is, the frame correcting unit 157 calculates a correction value to correct the count value of the frame pulse generator 156 on the basis of the count value of the baseband processing device 10 included in the control data signal. Then, the frame correcting unit 157 corrects the count value of the frame pulse generator 156 by the calculated correction value.
- the frame correcting unit 117 acquires the count value in the counter of the wireless device 50 and corrects the count value in the counter of the frame pulse generator 116 on the basis of the acquired count value.
- This configuration of the baseband processing device 10 allows the frame timing of the uplink of the baseband processing device 10 to synchronize with the frame timing of the wireless device 50 .
- the frame correction controller 153 acquires the count value from the frame pulse generator 154 and transmits the control data signal including the acquired count value to the baseband processing device 10 via the optical transmission line L 1 .
- This configuration of the wireless device 50 allows the frame timing of the uplink of the baseband processing device 10 to synchronize with the frame timing of the wireless device 50 .
- the frame correcting unit 157 acquires the count value in the counter of the baseband processing device 10 and corrects the count value in the counter of the frame pulse generator 156 on the basis of the acquired count value.
- This configuration of the wireless device 50 allows the frame timing of the downlink of the wireless device 50 to synchronize with the frame timing of the baseband processing device 10 .
- the frame correction controller 113 acquires the count value at the timing from the frame pulse generator 114 and transmits the control data signal including the acquired count value to the wireless device 50 via the optical transmission line L 1 .
- This configuration of the baseband processing device 10 allows the frame timing of the downlink of the wireless device 50 to synchronize with the frame timing of the baseband processing device 10 .
- a third embodiment relates to delay correction control in the distortion compensation processing.
- FIG. 9 is a block diagram illustrating one example of a baseband processing device of the third embodiment.
- a configuration relating to the delay correction control is illustrated in addition to the configuration of the baseband processing device 10 illustrated in FIG. 2 .
- the baseband processing device 10 includes a known signal generator 211 , a round-trip time calculator 212 , and a delay amount correcting unit 213 .
- the known signal generator 211 generates a known signal (hereinafter, often referred to as the “test data signal”) used to measure round-trip time and outputs the generated known signal to the multiplexer 21 . Furthermore, the known signal generator 211 outputs a “transmission timing notification signal” to notify the transmission timing to the round-trip time calculator 212 simultaneously with the output of the known signal to the multiplexer 21 .
- the round-trip time calculator 212 receives the “transmission timing notification signal” from the known signal generator 211 and acquires the timing notified by the signal (i.e. transmission timing). Then, when receiving a “return signal” that is transmitted from the wireless device 50 and is extracted in the extracting unit 15 , the round-trip time calculator 212 acquires the timing of the signal reception (i.e. reception timing). Then, the round-trip time calculator 212 calculates the round-trip time on the basis of the transmission timing and the reception timing.
- the round-trip time calculator 212 may start measurement of elapsed time upon receiving the “transmission timing notification signal” from the known signal generator 211 and end the measurement of the elapsed time upon receiving the “return signal,” and may employ the measured elapsed time as the round-trip time.
- the delay amount correcting unit 213 corrects a “set delay amounts” in the delay sections 34 , 35 , and 36 of the distortion compensating unit 12 on the basis of the round-trip time acquired in the round-trip time calculator 212 .
- the delay amount correcting unit 213 holds a “correspondence table” in a memory (not illustrated) and identifies the set delay amounts resulting from the correction on the basis of the round-trip time acquired in the round-trip time calculator 212 and the “correspondence table.”
- the “correspondence table” holds plural candidate values of the round-trip time and delay amounts according to the respective candidate values in association with each other.
- FIG. 10 is a block diagram illustrating one example of a wireless device of the third embodiment.
- the wireless device in FIG. 10 may be the wireless device 50 illustrated in FIG. 4 .
- the extracting unit 53 of the wireless device 50 extracts a “test data signal” from a signal other than a clock demultiplexed from a multiple signal in the demultiplexer 63 , and outputs the extracted “test data signal” to the multiplexer 64 as a “return signal.” This “return signal” is transmitted to the baseband processing device 10 .
- FIG. 11 is a flowchart illustrating one example of a processing operation of a baseband processing device of the third embodiment.
- the baseband processing device performing the processing operation in FIG. 11 may be the baseband processing device 10 illustrated in FIG. 5 .
- the known signal generator 211 transmits a test data signal to the wireless device 50 by outputting the test data signal to the multiplexer 21 (step S 301 ).
- the round-trip time calculator 212 receives a return signal responding to the transmitted test data signal (step S 302 ).
- the round-trip time calculator 212 calculates round-trip time on the basis of the transmission timing and the reception timing (S 303 ).
- the delay amount correcting unit 213 corrects a “set delay amounts” in the delay sections 34 , 35 , and 36 of the distortion compensating unit 12 on the basis of the round-trip time acquired in the round-trip time calculator 212 (step S 304 ).
- the known signal generator 211 transmits the test data signal to the wireless device 50 via the optical transmission line L 1 .
- the round-trip time calculator 212 calculates the round-trip time on the basis of the transmission timing of the test data signal and the reception timing of the return signal transmitted from the wireless device 50 in response to the test data signal.
- the delay amount correcting unit 213 corrects the set delay amounts in the delay sections 34 , 35 , and 36 of the distortion compensating unit 12 on the basis of the calculated round-trip time.
- the timing in the distortion compensation processing can be adjusted even when the length of the optical transmission line L 1 is changed for example.
- whether or not to execute the calculation processing and update processing of the distortion compensation coefficient is controlled depending on the status of the optical transmission line L 1 .
- FIG. 12 is a block diagram illustrating one example of a baseband processing device of the fourth embodiment.
- a configuration relating to control of whether or not to execute the distortion compensation processing is illustrated in addition to the configuration of the baseband processing device 10 illustrated in FIG. 2 .
- the baseband processing device 10 includes a monitoring unit 311 and a distortion compensation controller 312 .
- the monitoring unit 311 determines whether or not an error is present in a known signal (hereinafter, often referred to as the “frame synchronization bit”) that is transmitted from a wireless device 50 and is extracted in the extracting unit 15 .
- the distortion compensation controller 312 stops the calculation processing and update processing of the distortion compensation coefficient in the distortion compensating unit 12 .
- the distortion compensation controller 312 starts the calculation processing and update processing of the distortion compensation coefficient by the distortion compensating unit 12 .
- FIG. 13 is a block diagram illustrating one example of a wireless device of the fourth embodiment.
- a configuration relating to the control of whether or not to execute the distortion compensation processing is illustrated in addition to the configuration of the wireless device 50 illustrated in FIG. 4 .
- the wireless device 50 includes a known signal generator 351 .
- the known signal generator 351 generates the above-described frame synchronization bit and outputs the generated frame synchronization bit to the multiplexer 64 .
- This frame synchronization bit is transmitted by being mapped onto the beginning part of a frame for example.
- FIG. 14 is a flowchart illustrating one example of a processing operation of a baseband processing device of the fourth embodiment.
- the baseband processing device performing the processing operation in FIG. 14 may be the baseband processing device 10 illustrated in FIG. 12 .
- the monitoring unit 311 acquires a frame synchronization bit that is transmitted from the wireless device 50 and is extracted in the extracting unit 15 (step S 401 ).
- the monitoring unit 311 determines whether an error is absent in the acquired frame synchronization bit (step S 402 ).
- the distortion compensation controller 312 If an error is absent in the acquired frame synchronization bit (Yes of step S 402 ), in the state in which the calculation processing and update processing of the distortion compensation coefficient are stopped, the distortion compensation controller 312 starts the calculation processing and update processing. In the state in which the calculation processing and update processing of the distortion compensation coefficient are working, the distortion compensation controller 312 continues the calculation processing and update processing (step S 403 ). The distortion compensation controller 312 may start the calculation processing and update processing of the distortion compensation coefficient if an error is absent in the frame synchronization bits of plural frames for example.
- the distortion compensation controller 312 stops the calculation processing and update processing. In the state in which the calculation processing and update processing of the distortion compensation coefficient are stopped, the distortion compensation controller 312 continues the stop of the calculation processing and update processing (step S 404 ).
- step S 401 to step S 404 is repeatedly executed if an end condition is not satisfied (No of step S 405 ). If the end condition is satisfied (Yes of step S 405 ), the processing flow of FIG. 14 ends.
- the end condition is that the power supply of the baseband processing device 10 is turned OFF for example.
- the monitoring unit 311 monitors the frame synchronization bit transmitted from the wireless device 50 . Then, if an error is detected in the frame synchronization bit by the monitoring unit 311 , the distortion compensation controller 312 stops the calculation processing and update processing of the distortion compensation coefficient in the distortion compensating unit 12 .
- This configuration of the baseband processing device 10 can stop the calculation processing and update processing in a situation in which the calculation accuracy of the distortion compensation coefficient is lowered, and thus can reduce the lowering of the accuracy of the distortion compensation processing.
- the distortion compensating units 12 of the first embodiment to the fourth embodiment may adjust the distortion compensation coefficient according to the temperature of the wireless device 50 .
- the configurations of the baseband processing devices 10 described in each of the first embodiment to the fourth embodiment may all be provided in one baseband processing device 10 . Furthermore, the configurations of the wireless devices 50 described in each of the first embodiment to the fourth embodiment may all be provided in one wireless device 50 .
- the frame synchronization processing and the delay correction control processing described in the second embodiment and the third embodiment may be executed in one series of flow. That is, the frame synchronization processing and the delay correction control processing may be executed in that order.
- all or an arbitrary part of various kinds of processing functions carried out in the respective devices may be carried out on a central processing unit (CPU) or a microcomputer such as a micro processing unit (MPU) or a micro controller unit (MCU). Furthermore, all or an arbitrary part of the various kinds of processing functions may be carried out on a program analyzed and executed on a CPU or a microcomputer such as an MPU or an MCU or on hardware based on wired logic.
- CPU central processing unit
- MPU micro processing unit
- MCU micro controller unit
- the baseband processing devices 10 and the wireless devices 50 of the first embodiment to the fourth embodiment can be implemented by the following hardware configurations for example.
- FIG. 15 is a diagram illustrating a hardware configuration example of a baseband processing device.
- a baseband processing device 400 includes a processor 401 , a memory 402 , and an optical module 403 .
- the processor 401 include a CPU, a digital signal processor (DSP), a field programmable gate array (FPGA), and so forth.
- the memory 402 include a random access memory (RAM) such as a synchronous dynamic random access memory (SDRAM), a read only memory (ROM), a flash memory, and so forth.
- RAM random access memory
- SDRAM synchronous dynamic random access memory
- ROM read only memory
- flash memory and so forth.
- the various kinds of processing functions carried out in the baseband processing devices 10 of the first embodiment to the fourth embodiment may be implemented through execution of programs stored in various kinds of memories such as a non-volatile storage medium by a processor. That is, programs corresponding to each processing executed by the baseband unit 11 , the distortion compensating unit 12 , the high-speed serial interface unit 13 , the extracting unit 15 , the link-up controller 111 , the reference clock generators 112 and 115 , the frame correction controller 113 , the frame pulse generators 114 and 116 , the frame correcting unit 117 , the known signal generator 211 , the round-trip time calculator 212 , the delay amount correcting unit 213 , the monitoring unit 311 , and the distortion compensation controller 312 may be recorded in the memory 402 and the respective programs may be executed in the processor 401 .
- the optical interface unit 14 is implemented by the optical module 403 .
- the various kinds of processing functions carried out in the baseband processing devices 10 of the first embodiment to the fourth embodiment are carried out by the one processor 401 , the configuration is not limited thereto and the processing functions may be carried out by plural processors.
- FIG. 16 is a diagram illustrating a hardware configuration example of a wireless device.
- a wireless device 500 includes an optical module 501 , a processor 502 , a memory 503 , and a radio frequency (RF) circuit 504 .
- the processor 502 include a CPU, a DSP, an FPGA, and so forth.
- the memory 503 include a RAM such as an SDRAM, a ROM, a flash memory, and so forth.
- the various kinds of processing functions carried out in the wireless devices 50 of the first embodiment to the fourth embodiment may be implemented through execution of programs stored in various kinds of memories such as a non-volatile storage medium by a processor. That is, programs corresponding to each processing executed by the high-speed serial interface unit 52 , the extracting unit 53 , the link-up controller 151 , the reference clock generators 152 and 155 , the frame correction controller 153 , the frame pulse generators 154 and 156 , the frame correcting unit 157 , and the known signal generator 351 may be recorded in the memory 503 and the respective programs may be executed in the processor 502 .
- the wireless transmission unit 54 , the coupler 55 , the down-converter 56 , the A/D converter 57 , the circulator 58 , and the wireless reception unit 59 are implemented by the RF circuit 504 .
- the optical interface unit 51 is implemented by the optical module 501 .
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Abstract
A wireless communication system includes a baseband processing device configured to transmit a data signal via an optical transmission line, and a wireless device configured to receive the data signal via the optical transmission line and carry out wireless transmission of an output signal obtained by amplifying the data signal, wherein the wireless device is configured to amplify the data signal to generate the output signal, generate a feedback signal according to the output signal, and transmit the feedback signal to the baseband processing device via the optical transmission line, and wherein the baseband processing device is configured to acquire the feedback signal from the wireless device, and execute first processing of multiplying the data signal by a distortion compensation coefficient corresponding to an inverse characteristic of distortion in the radio frequency circuit based on the feedback signal.
Description
- This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2014-212086, filed on Oct. 16, 2014, the entire contents of which are incorporated herein by reference.
- The embodiments discussed herein are related to a wireless communication system, a baseband processing device, and a wireless device.
- Conventionally, wireless base station devices (hereinafter, often referred to simply as the “base station”) are provided with an amplifying unit that amplifies the power of a transmission signal. In general, in the base station, the amplifying unit is operated near the saturation region of the amplifying unit in order to enhance the power efficiency of the amplifying unit. However, when the amplifying unit is operated near the saturation region, non-linear distortion increases. Therefore, in order to suppress this non-linear distortion and reduce the adjacent channel leakage ratio (ACLR), the base station is provided with a distortion compensating unit that compensates for the non-linear distortion.
- As one of distortion compensation systems used in the distortion compensating unit, there is a “predistortion (hereinafter, often referred to as the “PD”) system.” The distortion compensating unit of the PD system enhances the linearity of the output of the amplifying unit and suppresses the distortion of the output of the amplifying unit by multiplying a transmission baseband signal before input to the amplifying unit by a distortion compensation coefficient having the inverse characteristic of the non-linear distortion of the amplifying unit in advance. The signal resulting from the multiplication of the transmission baseband signal by the distortion compensation coefficient is often referred to as the “PD signal.” Thus, the PD signal is a signal that gets distorted in advance before input to the amplifying unit in accordance with the inverse characteristic of the non-linear distortion of the amplifying unit.
- For example, as the distortion compensating unit of the PD system, there is one that includes a lookup table (LUT) in which plural distortion compensation coefficients are stored and specifies, to the LUT, an address according to the power of the transmission baseband signal to read out the distortion compensation coefficient from the LUT. The distortion compensation coefficients stored in the LUT are sequentially updated so that the error between the transmission baseband signal as a reference signal and a signal that is output from the amplifying unit and is fed back (hereinafter, often referred to as the “feedback signal”), obtained by comparing both signals, may be minimized. As a related-art document, there is Japanese Laid-open Patent Publication No. 2007-96775.
- According to an aspect of the embodiments, a wireless communication system includes a baseband processing device configured to transmit a data signal via an optical transmission line, and a wireless device configured to receive the data signal via the optical transmission line and carry out wireless transmission of an output signal obtained by amplifying the data signal, wherein the wireless device includes a radio frequency circuit configured to amplify the data signal to generate the output signal, a first memory, and a first processor coupled to the first memory and configured to generate a feedback signal according to the output signal generated by the radio frequency circuit, and transmit the feedback signal to the baseband processing device via the optical transmission line, and wherein the baseband processing device includes a second memory, and a second processor coupled to the second memory and configured to acquire the feedback signal from the wireless device, and execute first processing of multiplying the data signal by a distortion compensation coefficient corresponding to an inverse characteristic of distortion in the radio frequency circuit based on the feedback signal.
- The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
- It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.
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FIG. 1 is a block diagram illustrating one example of a wireless communication system of a first embodiment; -
FIG. 2 is a block diagram illustrating one example of a baseband processing device of the first embodiment; -
FIG. 3 is a block diagram illustrating one example of a distortion compensating unit of the first embodiment; -
FIG. 4 is a block diagram illustrating one example of a wireless device of the first embodiment; -
FIG. 5 is a block diagram illustrating one example of a baseband processing device of a second embodiment; -
FIG. 6 is a block diagram illustrating one example of a wireless device of the second embodiment; -
FIG. 7 is a flowchart illustrating one example of a processing operation of a baseband processing device of the second embodiment; -
FIG. 8 is a flowchart illustrating one example of a processing operation of a wireless device of the second embodiment; -
FIG. 9 is a block diagram illustrating one example of a baseband processing device of a third embodiment; -
FIG. 10 is a block diagram illustrating one example of a wireless device of the third embodiment; -
FIG. 11 is a flowchart illustrating one example of a processing operation of a baseband processing device of the third embodiment; -
FIG. 12 is a block diagram illustrating one example of a baseband processing device of a fourth embodiment; -
FIG. 13 is a block diagram illustrating one example of a wireless device of the fourth embodiment; -
FIG. 14 is a flowchart illustrating one example of a processing operation of a baseband processing device of the fourth embodiment; -
FIG. 15 is a diagram illustrating a hardware configuration example of a baseband processing device; and -
FIG. 16 is a diagram illustrating a hardware configuration example of a wireless device. - Various contrivances are being made in order to increase the transmission capacity in a communication system (hereinafter, the transmission capacity will be often referred to as the “system capacity”). For example, in the 3rd generation partnership project long term evolution (3GPP LTE), discussion relating to techniques for increasing the system capacity by utilizing “small cells” besides “macrocells” is being made. Here, the “cell” is prescribed on the basis of the “cover area” and the “channel frequency” of one base station device (hereinafter, often referred to simply as the “base station”). The “cover area” may be the whole of the area to which radio waves transmitted from the base station reach or may be a divided area (so-called sector) obtained by dividing the reach area. The “channel frequency” is one unit of the frequency used by the base station for communications and is prescribed on the basis of the center frequency and the bandwidth. Furthermore, the channel frequency is part of the “operating band” allocated to the whole system. The “macrocell” is the cell of a base station capable of transmission with high transmission power, i.e. a base station having a large cover area. The “small cell” is the cell of a base station that carries out transmission with low transmission power, i.e. a base station having a small cover area.
- To realize the shift to the small cells, a large number of small-cell base stations are to be disposed. Accordingly, studies are being made on a system in which the base station is divided into a baseband unit (BBU) and a remote radio head (RRH) and plural wireless devices are subordinated to one baseband processing device. Furthermore, it is desired to reduce the size of the wireless device in order to improve the flexibility in the placement of the base station.
- The disclosed techniques are made in view of the above and intend to provide a baseband processing device, a wireless device, and a wireless communication system that allow size reduction of the wireless device.
- Embodiments of a baseband processing device, a wireless device, and a wireless communication system disclosed by the present application will be described in detail below on the basis of the drawings. The baseband processing device, the wireless device, and the wireless communication system disclosed by the present application are not limited by the embodiments. Furthermore, a configuration having the same function in the embodiments is given the same symbol and overlapping description is omitted.
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FIG. 1 is a block diagram illustrating one example of a wireless communication system of a first embodiment. InFIG. 1 , awireless communication system 1 includes abaseband processing device 10, awireless device 50, and aterminal 90. Thebaseband processing device 10 and thewireless device 50 are coupled to each other by an optical transmission line L1. Thebaseband processing device 10 and thewireless device 50 are included in a base station. Thewireless device 50 and theterminal 90 are wirelessly coupled to each other. Although the numbers ofbaseband processing devices 10,wireless devices 50, andterminals 90 are each set to one inFIG. 1 , the numbers of them are not limited thereto. - The
wireless device 50 receives a transmission-object data signal that is transmitted by thebaseband processing device 10 and is to be delivered to theterminal 90 via the optical transmission line L1. Thewireless device 50 amplifies the received data signal by an amplifying unit to be described later and then carries out wireless transmission of the resulting data signal to theterminal 90. - Furthermore, the
wireless device 50 forms a “feedback signal” according to an output signal of the amplifying unit and transmits the formed feedback signal to thebaseband processing device 10 via the optical transmission line L1. - The
baseband processing device 10 acquires the feedback signal transmitted from thewireless device 50 and executes “distortion compensation processing” on the basis of the acquired feedback signal. The “distortion compensation processing” is processing of multiplying a transmission-object data signal by a distortion compensation coefficient corresponding to the inverse characteristic of distortion in the amplifying unit. - As described above, a distortion compensating unit that compensates for the distortion in the amplifying unit of the
wireless device 50 is provided not in thewireless device 50 but in thebaseband processing device 10. This can realize size reduction and power saving of thewireless device 50. - [Configuration Example of Baseband Processing Device]
-
FIG. 2 is a block diagram illustrating one example of a baseband processing device of the first embodiment. The baseband processing device inFIG. 2 may be thebaseband processing device 10 illustrated inFIG. 1 . InFIG. 2 , thebaseband processing device 10 includes abaseband unit 11, adistortion compensating unit 12, a high-speedserial interface unit 13, anoptical interface unit 14, and an extractingunit 15. The high-speedserial interface unit 13 includes a multiplexer 21 and ademultiplexer 22. Theoptical interface unit 14 includes an electrical/optical converter 23 and an optical/electrical converter 24. - The
baseband unit 11 generates a transmission baseband signal by executing baseband processing such as coding processing and modulation processing for input transmission data, and outputs the generated transmission baseband signal In(t) to thedistortion compensating unit 12. - The
distortion compensating unit 12 is a distortion compensating unit of the PD system and includes a LUT in which plural distortion compensation coefficients each corresponding to a respective one of plural addresses corresponding to plural power ranges are stored. Thedistortion compensating unit 12 generates a PD signal Out(t) by multiplying the transmission baseband signal by the distortion compensation coefficient read out from the LUT through reference to the LUT in accordance with an address generated according to the power of the transmission baseband signal. Thedistortion compensating unit 12 outputs the generated PD signal Out(t) to the high-speedserial interface unit 13. Furthermore, thedistortion compensating unit 12 updates the distortion compensation coefficients stored in the LUT on the basis of the error between the transmission baseband signal In(t) as a reference signal and a feedback signal FB(t). -
FIG. 3 is a block diagram illustrating one example of a distortion compensating unit of the first embodiment. The distortion compensating unit inFIG. 3 may be thedistortion compensating unit 12 illustrated inFIG. 2 . InFIG. 3 , thedistortion compensating unit 12 includes anaddress calculator 31, aLUT 32, amultiplier 33,delay sections compensation coefficient calculator 38. - The
address calculator 31 calculates an address on the basis of the power value and phase of the transmission baseband signal In(t). - The
LUT 32 reads out the distortion compensation coefficient corresponding to an address Adr(t) calculated in theaddress calculator 31 from a distortion compensation coefficient table and outputs the read distortion compensation coefficient to themultiplier 33 and thedelay section 35. Furthermore, theLUT 32 updates the distortion compensation coefficient table by using an update value of the distortion compensation coefficient calculated in thecompensation coefficient calculator 38 and an update address received from thedelay section 34. - For example, the
LUT 32 includes an updatingsection 41, a table storing section 42, and areading section 43 as illustrated inFIG. 3 . - The updating
section 41 executes update processing of updating the distortion compensation coefficient table by using the update value of the distortion compensation coefficient calculated in thecompensation coefficient calculator 38 and the update address received from thedelay section 34. - The table storing section 42 stores the “distortion compensation coefficient table” in which plural distortion compensation coefficients each corresponding to a respective one of plural address values are stored.
- The
reading section 43 reads out the distortion compensation coefficient corresponding to the address Adr(t) calculated in theaddress calculator 31 from the distortion compensation coefficient table and outputs the read distortion compensation coefficient to themultiplier 33 and thedelay section 35. - The
multiplier 33 multiplies the transmission baseband signal In(t) and the distortion compensation coefficient from theLUT 32 and outputs the transmission baseband signal In(t) resulting from the distortion compensation processing, i.e. the PD signal Out(t), to the high-speedserial interface unit 13. - The
delay section 34 delays the address Adr(t) by the amount d1 of delay and outputs the delayed address Adr(t) to the updatingsection 41 as the update address. The amount d1 of delay corresponds to the total delay time taken until the transmission baseband signal In(t) is transmitted to thewireless device 50 and the update value of the distortion compensation coefficient is calculated on the basis of the feedback signal FB(t) transmitted from thewireless device 50 in response to the transmission baseband signal In(t). - The
delay section 35 delays the distortion compensation coefficient output from theLUT 32 by the amount d2 of delay and outputs the delayed distortion compensation coefficient to thecompensation coefficient calculator 38. The amount d2 of delay corresponds to the total delay time taken until the transmission baseband signal In(t) is transmitted to thewireless device 50 and the difference between the feedback signal FB(t) transmitted from thewireless device 50 in response to the transmission baseband signal In(t) and the transmission baseband signal In(t) is calculated. - The
delay section 36 delays the transmission baseband signal In(t) as the reference signal by the amount d3 of delay and outputs the delayed reference signal to the comparator 37. The amount d3 of delay corresponds to the total delay time taken until the transmission baseband signal In(t) is transmitted to thewireless device 50 and the feedback signal FB(t) transmitted from thewireless device 50 in response to the transmission baseband signal In(t) is input to the comparator 37. - The comparator 37 compares the transmission baseband signal In(t) as the reference signal with the feedback signal FB(t) to calculate an error signal e(t) of both signals and output the calculated error signal e(t) to the
compensation coefficient calculator 38. - The
compensation coefficient calculator 38 calculates the update value of the distortion compensation coefficient on the basis of the error signal e(t) received from the comparator 37 and the distortion compensation coefficient received via thedelay section 35, and outputs the calculated update value of the distortion compensation coefficient to the updatingsection 41. - Referring back to
FIG. 2 , the high-speedserial interface unit 13 is compliant with the JEDEC standards (JESD), which is a serial interface standard, for example. The high-speedserial interface unit 13 multiplexes (superimposes) a clock (i.e. timing information) on the transmission baseband signal In(t) resulting from the distortion compensation processing and outputs the multiple signal to theoptical interface unit 14. Furthermore, the high-speedserial interface unit 13 demultiplexes a multiple signal received from theoptical interface unit 14 into a clock and a signal other than the clock. As illustrated inFIG. 2 , the high-speedserial interface unit 13 includes the multiplexer 21 and thedemultiplexer 22. The above-described multiplexing processing is executed in the multiplexer 21 and the above-described demultiplexing processing is executed in thedemultiplexer 22. - The
optical interface unit 14 includes the electrical/optical converter 23 and the optical/electrical converter 24. The electrical/optical converter 23 converts the multiple signal received from the high-speedserial interface unit 13 from an electrical signal to an optical signal and sends out the obtained optical signal to the optical transmission line L1. The sent optical signal is transmitted to thewireless device 50. The optical/electrical converter 24 receives an optical signal transmitted from thewireless device 50 and converts the received optical signal to an electrical signal to output the obtained electrical signal, i.e. a received electrical signal, to thedemultiplexer 22. - The extracting
unit 15 extracts the feedback signal FB(t) from the signal other than the clock, obtained in thedemultiplexer 22, and outputs the extracted feedback signal FB(t) to thedistortion compensating unit 12. - [Configuration Example of Wireless Device]
-
FIG. 4 is a block diagram illustrating one example of a wireless device of the first embodiment. The wireless device inFIG. 4 may be thewireless device 50 illustrated inFIG. 1 . InFIG. 4 , thewireless device 50 includes anoptical interface unit 51, a high-speedserial interface unit 52, an extractingunit 53, awireless transmission unit 54, acoupler 55, a down-converter 56, an analog-digital (A/D)converter 57, acirculator 58, and awireless reception unit 59. - The
optical interface unit 51 includes an optical/electrical converter 61 and an electrical/optical converter 62. The optical/electrical converter 61 receives an optical signal transmitted from thebaseband processing device 10 and converts the received optical signal to an electrical signal to output the obtained electrical signal (i.e. received electrical signal) to the high-speedserial interface unit 52. The electrical/optical converter 62 converts a multiple signal received from the high-speedserial interface unit 52 from an electrical signal to an optical signal and sends out the obtained optical signal to the optical transmission line L1. The sent optical signal is transmitted to thebaseband processing device 10. - The high-speed
serial interface unit 52 is compliant with the JESD standard, which is a serial interface standard, for example. The high-speedserial interface unit 52 demultiplexes the received electrical signal received from the optical/electrical converter 61 into a clock and a signal other than the clock. The high-speedserial interface unit 52 multiplexes (superimposes) a clock, i.e. timing information, on a feedback signal received from the A/D converter 57 and a received signal received from thewireless reception unit 59 and outputs the multiple signal to theoptical interface unit 51. As illustrated inFIG. 4 , the high-speedserial interface unit 52 includes ademultiplexer 63 and amultiplexer 64. The above-described multiplexing processing is executed in themultiplexer 64 and the above-described demultiplexing processing is executed in thedemultiplexer 63. - The extracting
unit 53 extracts a data signal from the signal other than the clock, obtained in thedemultiplexer 63, and outputs the extracted data signal to thewireless transmission unit 54. - The
wireless transmission unit 54 executes given wireless processing, for example, digital-analog conversion, up-conversion, amplification, and so forth, on the data signal extracted in the extractingunit 53 and outputs the obtained wireless signal to thecoupler 55. Thewireless transmission unit 54 includes a digital-analog (D/A)converter 65, an up-converter 66, and an amplifying section 67 as illustrated inFIG. 4 . The above-described digital-analog conversion processing is executed in the D/A converter 65. The above-described up-conversion processing is executed in the up-converter 66. The above-described amplification processing is executed in the amplifying section 67. - The
coupler 55 distributes the wireless signal output from thewireless transmission unit 54 to thecirculator 58 and the down-converter 56. Thereby, the output signal of the amplifying section 67 is fed back to thebaseband processing device 10 via the down-converter 56 and the A/D converter 57. - The down-
converter 56 carries out down-conversion of the signal input from thecoupler 55 and outputs the down-converted signal to the A/D converter 57. - The A/
D converter 57 converts the down-converted signal from an analog signal to a digital signal and outputs the digital signal resulting from the conversion to themultiplexer 64 as the feedback signal FB(t). - The
circulator 58 transmits the wireless signal output from thecoupler 55 via an antenna. Furthermore, thecirculator 58 outputs a signal received via the antenna to thewireless reception unit 59. - The
wireless reception unit 59 executes given wireless reception processing, for example, down-conversion, analog-digital conversion, and so forth, on the wireless signal received from thecirculator 58 and outputs the obtained received signal to themultiplexer 64. - As described above, according to the present embodiment, the
baseband processing device 10 includes thedistortion compensating unit 12 that compensates for distortion in the amplifying section 67 of thewireless device 50. - This configuration of the
baseband processing device 10 can remove the distortion compensating unit from thewireless device 50 and thus realize size reduction of thewireless device 50. - Furthermore, in the
wireless device 50, the down-converter 56 and the A/D converter 57 as a forming unit of the feedback signal form a feedback signal according to the output signal of the amplifying section 67, and the high-speedserial interface unit 52 and theoptical interface unit 51 as a transmitting unit transmit the feedback signal to thebaseband processing device 10 via the optical transmission line L1. - This configuration of the
wireless device 50 allows the distortion compensation processing to be executed in thebaseband processing device 10. As a result, size reduction of thewireless device 50 can be realized. - A second embodiment relates to frame synchronization processing between a baseband processing device and a wireless device.
- [Configuration Example of Baseband Processing Device]
-
FIG. 5 is a block diagram illustrating one example of a baseband processing device of the second embodiment. InFIG. 5 , a configuration relating to the frame synchronization processing is illustrated in addition to the configuration of thebaseband processing device 10 illustrated inFIG. 2 . - In
FIG. 5 , thebaseband processing device 10 includes a link-up controller 111,reference clock generators frame pulse generators frame correcting unit 117. Here, thereference clock generators reference clock generators frame pulse generators - The link-up controller 111 controls link-up of the downlink line, i.e. the line of the direction from the
baseband processing device 10 to awireless device 50. For example, the link-up controller 111 outputs a K code to the multiplexer 21 in a link-up procedure. A clock is multiplexed on this K code and the resulting K code is transmitted to thewireless device 50. - Furthermore, the link-up controller 111 outputs an output command of a “start trigger pulse” to the
reference clock generator 112 after the elapse of a given time from the start of the link-up procedure. By this output command, the “start trigger pulse” is output from thereference clock generator 112 to theframe pulse generator 114, and theframe pulse generator 114 outputs a frame pulse to the multiplexer 21 every frame. The “start trigger pulse” is e.g. a one-pulse signal. - Moreover, when the output of the frame pulse is started, the link-up controller 111 receives a “link-up request signal” from the
frame pulse generator 114 and outputs an initial lane alignment sequence (ILAS) pattern to the multiplexer 21 in response to this “link-up request signal.” A clock is multiplexed on this ILAS pattern and the resulting ILAS pattern is transmitted to thewireless device 50. - In addition, after outputting the ILAS pattern, the link-up controller 111 outputs a “correction control start command” to the frame correction controller 113. This causes the frame correction controller 113 to output a count value of the
frame pulse generator 114 to the multiplexer 21. This count value is transmitted to thewireless device 50. - When receiving the output command of the “start trigger pulse” from the link-up controller 111, the
reference clock generator 112 outputs the “start trigger pulse” to theframe pulse generator 114. - When receiving the “start trigger pulse” from the
reference clock generator 112, theframe pulse generator 114 starts the output of the frame pulse. For example, theframe pulse generator 114 includes a counter and outputs the frame pulse to the multiplexer 21 every time the count value of the counter becomes the value corresponding to one frame. Furthermore, when starting the output of the frame pulse, theframe pulse generator 114 outputs the above-described “link-up request signal” to the link-up controller 111. - When receiving the “correction control start command” from the link-up controller 111, the frame correction controller 113 acquires the count value at the timing from the
frame pulse generator 114 and outputs a control data signal including the acquired count value to the multiplexer 21. This control data signal is transmitted to thewireless device 50. - When receiving a clock obtained by being demultiplexed from a multiple signal in the
demultiplexer 22, thereference clock generator 115 outputs a “start trigger pulse” to theframe pulse generator 116. - When receiving the “start trigger pulse” from the
reference clock generator 115, theframe pulse generator 116 starts output of a frame pulse. For example, theframe pulse generator 116 includes a counter and outputs the frame pulse to thedemultiplexer 22 every time the count value of the counter becomes the value corresponding to one frame. - When receiving a control data signal that is transmitted from the
wireless device 50 and is extracted in the extractingunit 15, theframe correcting unit 117 acquires the count value at the timing from theframe pulse generator 116. Then, theframe correcting unit 117 calculates a correction value to correct the count value of theframe pulse generator 116 on the basis of the count value of thewireless device 50 included in the control data signal. Then, theframe correcting unit 117 corrects the count value of theframe pulse generator 116 by the calculated correction value. For example, theframe correcting unit 117 calculates the correction value by subtracting the count value of thewireless device 50 included in the control data signal from the count value of theframe pulse generator 116. - [Configuration Example of Wireless Device]
-
FIG. 6 is a block diagram illustrating one example of a wireless device of the second embodiment. InFIG. 6 , a configuration relating to the frame synchronization processing is illustrated in addition to the configuration of thewireless device 50 illustrated inFIG. 4 . Furthermore, the processing operation of functional units relating to the frame synchronization processing of thewireless device 50 of the second embodiment is basically the same as the processing operation of functional units relating to the frame synchronization processing of the above-describedbaseband processing device 10 of the second embodiment. - In
FIG. 6 , thewireless device 50 includes a link-upcontroller 151,reference clock generators frame correction controller 153, frame pulse generators 154 and 156, and aframe correcting unit 157. Here, thereference clock generators reference clock generators - The link-up
controller 151 controls link-up of the uplink line, i.e. the line of the direction from thewireless device 50 to thebaseband processing device 10. For example, the link-upcontroller 151 outputs a K code to themultiplexer 64 in a link-up procedure. A clock is multiplexed on this K code and the resulting K code is transmitted to thebaseband processing device 10. - Furthermore, the link-up
controller 151 outputs an output command of a “start trigger pulse” to thereference clock generator 152 after the elapse of a given time from the start of the link-up procedure. By this output command, the “start trigger pulse” is output from thereference clock generator 152 to the frame pulse generator 154, and the frame pulse generator 154 outputs a frame pulse to themultiplexer 64 every frame. The “start trigger pulse” is e.g. a one-pulse signal. - Moreover, when the output of the frame pulse is started, the link-up
controller 151 receives a “link-up request signal” from the frame pulse generator 154 and outputs an ILAS pattern to themultiplexer 64 in response to this “link-up request signal.” A clock is multiplexed on this ILAS pattern and the resulting ILAS pattern is transmitted to thebaseband processing device 10. - In addition, after outputting the ILAS pattern, the link-up
controller 151 outputs a “correction control start command” to theframe correction controller 153. This causes theframe correction controller 153 to output a count value of the frame pulse generator 154 to themultiplexer 64. This count value is transmitted to thebaseband processing device 10. - When receiving the output command of the “start trigger pulse” from the link-up
controller 151, thereference clock generator 152 outputs the “start trigger pulse” to the frame pulse generator 154. - When receiving the “start trigger pulse” from the
reference clock generator 152, the frame pulse generator 154 starts the output of the frame pulse. For example, the frame pulse generator 154 includes a counter and outputs the frame pulse to themultiplexer 64 every time the count value of the counter becomes the value corresponding to one frame. Furthermore, when starting the output of the frame pulse, the frame pulse generator 154 outputs the above-described “link-up request signal” to the link-upcontroller 151. - When receiving the “correction control start command” from the link-up
controller 151, theframe correction controller 153 acquires the count value at the timing from the frame pulse generator 154 and outputs a control data signal including the acquired count value to themultiplexer 64. This control data signal is transmitted to thebaseband processing device 10. - When receiving a clock obtained by being demultiplexed from a multiple signal in the
demultiplexer 63, thereference clock generator 155 outputs a “start trigger pulse” to the frame pulse generator 156. - When receiving the “start trigger pulse” from the
reference clock generator 155, the frame pulse generator 156 starts output of a frame pulse. For example, the frame pulse generator 156 includes a counter and outputs the frame pulse to thedemultiplexer 63 every time the count value of the counter becomes the value corresponding to one frame. - When receiving a control data signal that is transmitted from the
baseband processing device 10 and is extracted in the extractingunit 53, theframe correcting unit 157 acquires the count value at the timing from the frame pulse generator 156. Then, theframe correcting unit 157 calculates a correction value to correct the count value of the frame pulse generator 156 on the basis of the count value of thebaseband processing device 10 included in the control data signal. Then, theframe correcting unit 157 corrects the count value of the frame pulse generator 156 by the calculated correction value. For example, theframe correcting unit 157 calculates the correction value by subtracting the count value of thebaseband processing device 10 included in the control data signal from the count value of the frame pulse generator 156. - [Operation Example of Wireless Communication System]
- One example of a processing operation of a wireless communication system of the second embodiment including the above configuration will be described. Here, particularly a processing operation relating to frame synchronization processing of downlink will be described.
FIG. 7 is a flowchart illustrating one example of a processing operation of a baseband processing device of the second embodiment. The baseband processing device performing the processing operation inFIG. 7 may be thebaseband processing device 10 illustrated inFIG. 5 . - In the
baseband processing device 10, the link-up controller 111 outputs a K code to the multiplexer 21 (step S101). - The
reference clock generator 112 outputs a “start trigger pulse” to the frame pulse generator 114 (step S102). Here, thereference clock generator 112 outputs the “start trigger pulse” when receiving an output command of the “start trigger pulse” from the link-up controller 111. The link-up controller 111 outputs the output command of the “start trigger pulse” to thereference clock generator 112 after the elapse of a given time from the start of a link-up procedure. - When receiving the “start trigger pulse” from the
reference clock generator 112, theframe pulse generator 114 starts output of a frame pulse (step S103). - When starting the output of the frame pulse, the
frame pulse generator 114 outputs a “link-up request signal” to the link-up controller 111 (step S104). - When receiving the “link-up request signal” from the
frame pulse generator 114, the link-up controller 111 transmits an ILAS pattern to the wireless device 50 (step S105). - After outputting the ILAS pattern, the link-up controller 111 outputs a “correction control start command” to the frame correction controller 113 (step S106).
- When receiving the “correction control start command” from the link-up controller 111, the frame correction controller 113 acquires a count value at the timing from the frame pulse generator 114 (step S107).
- The frame correction controller 113 transmits a control data signal including the acquired count value to the wireless device 50 (step S108).
-
FIG. 8 is a flowchart illustrating one example of a processing operation of a wireless device of the second embodiment. The wireless device performing the processing operation inFIG. 8 may be thewireless device 50 illustrated inFIG. 6 . - In the
wireless device 50, thereference clock generator 155 acquires a clock obtained by being demultiplexed from a multiple signal in the demultiplexer 63 (step S201). - When receiving the clock obtained by being demultiplexed from the multiple signal in the
demultiplexer 63, thereference clock generator 155 outputs a “start trigger pulse” to the frame pulse generator 156 (step S202). - When receiving the “start trigger pulse” from the
reference clock generator 155, the frame pulse generator 156 starts output of a frame pulse (step S203). - The
frame correcting unit 157 acquires a control data signal (including a count value) that is transmitted from thebaseband processing device 10 and is extracted in the extracting unit 53 (step S204). - When receiving the control data signal, the
frame correcting unit 157 acquires a count value at the timing from the frame pulse generator 156 (step S205). - The
frame correcting unit 157 executes correction processing on the basis of the count value of thebaseband processing device 10 included in the control data signal and the count value of the frame pulse generator 156 (step S206). That is, theframe correcting unit 157 calculates a correction value to correct the count value of the frame pulse generator 156 on the basis of the count value of thebaseband processing device 10 included in the control data signal. Then, theframe correcting unit 157 corrects the count value of the frame pulse generator 156 by the calculated correction value. - As described above, according to the present embodiment, in the
baseband processing device 10, theframe correcting unit 117 acquires the count value in the counter of thewireless device 50 and corrects the count value in the counter of theframe pulse generator 116 on the basis of the acquired count value. - This configuration of the
baseband processing device 10 allows the frame timing of the uplink of thebaseband processing device 10 to synchronize with the frame timing of thewireless device 50. - Furthermore, in the
wireless device 50, theframe correction controller 153 acquires the count value from the frame pulse generator 154 and transmits the control data signal including the acquired count value to thebaseband processing device 10 via the optical transmission line L1. - This configuration of the
wireless device 50 allows the frame timing of the uplink of thebaseband processing device 10 to synchronize with the frame timing of thewireless device 50. - Moreover, in the
wireless device 50, theframe correcting unit 157 acquires the count value in the counter of thebaseband processing device 10 and corrects the count value in the counter of the frame pulse generator 156 on the basis of the acquired count value. - This configuration of the
wireless device 50 allows the frame timing of the downlink of thewireless device 50 to synchronize with the frame timing of thebaseband processing device 10. - Furthermore, in the
baseband processing device 10, the frame correction controller 113 acquires the count value at the timing from theframe pulse generator 114 and transmits the control data signal including the acquired count value to thewireless device 50 via the optical transmission line L1. - This configuration of the
baseband processing device 10 allows the frame timing of the downlink of thewireless device 50 to synchronize with the frame timing of thebaseband processing device 10. - A third embodiment relates to delay correction control in the distortion compensation processing.
- [Configuration Example of Baseband Processing Device]
-
FIG. 9 is a block diagram illustrating one example of a baseband processing device of the third embodiment. InFIG. 9 , a configuration relating to the delay correction control is illustrated in addition to the configuration of thebaseband processing device 10 illustrated inFIG. 2 . - In
FIG. 9 , thebaseband processing device 10 includes a knownsignal generator 211, a round-trip time calculator 212, and a delayamount correcting unit 213. - The known
signal generator 211 generates a known signal (hereinafter, often referred to as the “test data signal”) used to measure round-trip time and outputs the generated known signal to the multiplexer 21. Furthermore, the knownsignal generator 211 outputs a “transmission timing notification signal” to notify the transmission timing to the round-trip time calculator 212 simultaneously with the output of the known signal to the multiplexer 21. - The round-
trip time calculator 212 receives the “transmission timing notification signal” from the knownsignal generator 211 and acquires the timing notified by the signal (i.e. transmission timing). Then, when receiving a “return signal” that is transmitted from thewireless device 50 and is extracted in the extractingunit 15, the round-trip time calculator 212 acquires the timing of the signal reception (i.e. reception timing). Then, the round-trip time calculator 212 calculates the round-trip time on the basis of the transmission timing and the reception timing. The round-trip time calculator 212 may start measurement of elapsed time upon receiving the “transmission timing notification signal” from the knownsignal generator 211 and end the measurement of the elapsed time upon receiving the “return signal,” and may employ the measured elapsed time as the round-trip time. - The delay
amount correcting unit 213 corrects a “set delay amounts” in thedelay sections distortion compensating unit 12 on the basis of the round-trip time acquired in the round-trip time calculator 212. For example, the delayamount correcting unit 213 holds a “correspondence table” in a memory (not illustrated) and identifies the set delay amounts resulting from the correction on the basis of the round-trip time acquired in the round-trip time calculator 212 and the “correspondence table.” The “correspondence table” holds plural candidate values of the round-trip time and delay amounts according to the respective candidate values in association with each other. - [Configuration Example of Wireless Device]
-
FIG. 10 is a block diagram illustrating one example of a wireless device of the third embodiment. The wireless device inFIG. 10 may be thewireless device 50 illustrated inFIG. 4 . - In
FIG. 10 , the extractingunit 53 of thewireless device 50 extracts a “test data signal” from a signal other than a clock demultiplexed from a multiple signal in thedemultiplexer 63, and outputs the extracted “test data signal” to themultiplexer 64 as a “return signal.” This “return signal” is transmitted to thebaseband processing device 10. - [Operation Example of Wireless Communication System]
- One example of a processing operation of a wireless communication system of the third embodiment including the above configuration will be described. Here, particularly a processing operation of a baseband processing device will be described.
FIG. 11 is a flowchart illustrating one example of a processing operation of a baseband processing device of the third embodiment. The baseband processing device performing the processing operation inFIG. 11 may be thebaseband processing device 10 illustrated inFIG. 5 . - The known
signal generator 211 transmits a test data signal to thewireless device 50 by outputting the test data signal to the multiplexer 21 (step S301). - The round-
trip time calculator 212 receives a return signal responding to the transmitted test data signal (step S302). - The round-
trip time calculator 212 calculates round-trip time on the basis of the transmission timing and the reception timing (S303). - The delay
amount correcting unit 213 corrects a “set delay amounts” in thedelay sections distortion compensating unit 12 on the basis of the round-trip time acquired in the round-trip time calculator 212 (step S304). - As described above, according to the present embodiment, in the
baseband processing device 10, the knownsignal generator 211 transmits the test data signal to thewireless device 50 via the optical transmission line L1. Then, the round-trip time calculator 212 calculates the round-trip time on the basis of the transmission timing of the test data signal and the reception timing of the return signal transmitted from thewireless device 50 in response to the test data signal. Then, the delayamount correcting unit 213 corrects the set delay amounts in thedelay sections distortion compensating unit 12 on the basis of the calculated round-trip time. - Due to this configuration of the
baseband processing device 10, the timing in the distortion compensation processing can be adjusted even when the length of the optical transmission line L1 is changed for example. - In a fourth embodiment, whether or not to execute the calculation processing and update processing of the distortion compensation coefficient is controlled depending on the status of the optical transmission line L1.
- [Configuration Example of Baseband Processing Device]
-
FIG. 12 is a block diagram illustrating one example of a baseband processing device of the fourth embodiment. InFIG. 12 , a configuration relating to control of whether or not to execute the distortion compensation processing is illustrated in addition to the configuration of thebaseband processing device 10 illustrated inFIG. 2 . - In
FIG. 12 , thebaseband processing device 10 includes a monitoring unit 311 and adistortion compensation controller 312. - The monitoring unit 311 determines whether or not an error is present in a known signal (hereinafter, often referred to as the “frame synchronization bit”) that is transmitted from a
wireless device 50 and is extracted in the extractingunit 15. - If it is determined in the monitoring unit 311 that an error is present, the
distortion compensation controller 312 stops the calculation processing and update processing of the distortion compensation coefficient in thedistortion compensating unit 12. On the other hand, if it is determined in the monitoring unit 311 that an error is absent in a status in which the calculation processing and update processing of the distortion compensation coefficient are stopped, thedistortion compensation controller 312 starts the calculation processing and update processing of the distortion compensation coefficient by thedistortion compensating unit 12. - [Configuration Example of Wireless Device]
-
FIG. 13 is a block diagram illustrating one example of a wireless device of the fourth embodiment. InFIG. 13 , a configuration relating to the control of whether or not to execute the distortion compensation processing is illustrated in addition to the configuration of thewireless device 50 illustrated inFIG. 4 . - In
FIG. 13 , thewireless device 50 includes a knownsignal generator 351. - The known
signal generator 351 generates the above-described frame synchronization bit and outputs the generated frame synchronization bit to themultiplexer 64. This frame synchronization bit is transmitted by being mapped onto the beginning part of a frame for example. - [Operation Example of Wireless Communication System]
- One example of a processing operation of a wireless communication system of the fourth embodiment including the above configuration will be described. Here, particularly a processing operation of a baseband processing device will be described.
FIG. 14 is a flowchart illustrating one example of a processing operation of a baseband processing device of the fourth embodiment. The baseband processing device performing the processing operation inFIG. 14 may be thebaseband processing device 10 illustrated inFIG. 12 . - In the
baseband processing device 10, the monitoring unit 311 acquires a frame synchronization bit that is transmitted from thewireless device 50 and is extracted in the extracting unit 15 (step S401). - The monitoring unit 311 determines whether an error is absent in the acquired frame synchronization bit (step S402).
- If an error is absent in the acquired frame synchronization bit (Yes of step S402), in the state in which the calculation processing and update processing of the distortion compensation coefficient are stopped, the
distortion compensation controller 312 starts the calculation processing and update processing. In the state in which the calculation processing and update processing of the distortion compensation coefficient are working, thedistortion compensation controller 312 continues the calculation processing and update processing (step S403). Thedistortion compensation controller 312 may start the calculation processing and update processing of the distortion compensation coefficient if an error is absent in the frame synchronization bits of plural frames for example. - If an error is present in the acquired frame synchronization bit (No of step S402), in the state in which the calculation processing and update processing of the distortion compensation coefficient are working, the
distortion compensation controller 312 stops the calculation processing and update processing. In the state in which the calculation processing and update processing of the distortion compensation coefficient are stopped, thedistortion compensation controller 312 continues the stop of the calculation processing and update processing (step S404). - The processing of step S401 to step S404 is repeatedly executed if an end condition is not satisfied (No of step S405). If the end condition is satisfied (Yes of step S405), the processing flow of
FIG. 14 ends. The end condition is that the power supply of thebaseband processing device 10 is turned OFF for example. - As described above, according to the present embodiment, in the
baseband processing device 10, the monitoring unit 311 monitors the frame synchronization bit transmitted from thewireless device 50. Then, if an error is detected in the frame synchronization bit by the monitoring unit 311, thedistortion compensation controller 312 stops the calculation processing and update processing of the distortion compensation coefficient in thedistortion compensating unit 12. - This configuration of the
baseband processing device 10 can stop the calculation processing and update processing in a situation in which the calculation accuracy of the distortion compensation coefficient is lowered, and thus can reduce the lowering of the accuracy of the distortion compensation processing. - [1] The
distortion compensating units 12 of the first embodiment to the fourth embodiment may adjust the distortion compensation coefficient according to the temperature of thewireless device 50. - [2] The configurations of the
baseband processing devices 10 described in each of the first embodiment to the fourth embodiment may all be provided in onebaseband processing device 10. Furthermore, the configurations of thewireless devices 50 described in each of the first embodiment to the fourth embodiment may all be provided in onewireless device 50. - [3] The frame synchronization processing and the delay correction control processing described in the second embodiment and the third embodiment may be executed in one series of flow. That is, the frame synchronization processing and the delay correction control processing may be executed in that order.
- [4] The respective constituent elements of the respective units illustrated in the drawings in the first embodiment to the fourth embodiment do not necessarily need be configured as illustrated in the drawings physically. That is, specific forms of distribution and integration of the respective units are not limited to the illustrated forms and all or part of the respective units can be configured to be distributed or integrated functionally or physically in an arbitrary unit according to various kinds of loads, the status of use, and so forth.
- Moreover, all or an arbitrary part of various kinds of processing functions carried out in the respective devices may be carried out on a central processing unit (CPU) or a microcomputer such as a micro processing unit (MPU) or a micro controller unit (MCU). Furthermore, all or an arbitrary part of the various kinds of processing functions may be carried out on a program analyzed and executed on a CPU or a microcomputer such as an MPU or an MCU or on hardware based on wired logic.
- The
baseband processing devices 10 and thewireless devices 50 of the first embodiment to the fourth embodiment can be implemented by the following hardware configurations for example. -
FIG. 15 is a diagram illustrating a hardware configuration example of a baseband processing device. As illustrated inFIG. 15 , abaseband processing device 400 includes aprocessor 401, amemory 402, and anoptical module 403. Examples of theprocessor 401 include a CPU, a digital signal processor (DSP), a field programmable gate array (FPGA), and so forth. Examples of thememory 402 include a random access memory (RAM) such as a synchronous dynamic random access memory (SDRAM), a read only memory (ROM), a flash memory, and so forth. - Furthermore, the various kinds of processing functions carried out in the
baseband processing devices 10 of the first embodiment to the fourth embodiment may be implemented through execution of programs stored in various kinds of memories such as a non-volatile storage medium by a processor. That is, programs corresponding to each processing executed by thebaseband unit 11, thedistortion compensating unit 12, the high-speedserial interface unit 13, the extractingunit 15, the link-up controller 111, thereference clock generators frame pulse generators frame correcting unit 117, the knownsignal generator 211, the round-trip time calculator 212, the delayamount correcting unit 213, the monitoring unit 311, and thedistortion compensation controller 312 may be recorded in thememory 402 and the respective programs may be executed in theprocessor 401. Theoptical interface unit 14 is implemented by theoptical module 403. - Although it is assumed here that the various kinds of processing functions carried out in the
baseband processing devices 10 of the first embodiment to the fourth embodiment are carried out by the oneprocessor 401, the configuration is not limited thereto and the processing functions may be carried out by plural processors. -
FIG. 16 is a diagram illustrating a hardware configuration example of a wireless device. As illustrated inFIG. 16 , awireless device 500 includes anoptical module 501, aprocessor 502, amemory 503, and a radio frequency (RF)circuit 504. Examples of theprocessor 502 include a CPU, a DSP, an FPGA, and so forth. Examples of thememory 503 include a RAM such as an SDRAM, a ROM, a flash memory, and so forth. - Furthermore, the various kinds of processing functions carried out in the
wireless devices 50 of the first embodiment to the fourth embodiment may be implemented through execution of programs stored in various kinds of memories such as a non-volatile storage medium by a processor. That is, programs corresponding to each processing executed by the high-speedserial interface unit 52, the extractingunit 53, the link-upcontroller 151, thereference clock generators frame correction controller 153, the frame pulse generators 154 and 156, theframe correcting unit 157, and the knownsignal generator 351 may be recorded in thememory 503 and the respective programs may be executed in theprocessor 502. Thewireless transmission unit 54, thecoupler 55, the down-converter 56, the A/D converter 57, thecirculator 58, and thewireless reception unit 59 are implemented by theRF circuit 504. Theoptical interface unit 51 is implemented by theoptical module 501. - Although it is assumed here that the various kinds of processing functions carried out in the
wireless devices 50 of the first embodiment to the fourth embodiment are carried out by the oneprocessor 502, the configuration is not limited thereto and the processing functions may be carried out by plural processors. - All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
Claims (13)
1. A wireless communication system comprising:
a baseband processing device configured to transmit a data signal via an optical transmission line; and
a wireless device configured to receive the data signal via the optical transmission line and carry out wireless transmission of an output signal obtained by amplifying the data signal,
wherein the wireless device includes
a radio frequency circuit configured to amplify the data signal to generate the output signal,
a first memory, and
a first processor coupled to the first memory and configured to
generate a feedback signal according to the output signal generated by the radio frequency circuit, and
transmit the feedback signal to the baseband processing device via the optical transmission line, and
wherein the baseband processing device includes
a second memory, and
a second processor coupled to the second memory and configured to
acquire the feedback signal from the wireless device, and
execute first processing of multiplying the data signal by a distortion compensation coefficient corresponding to an inverse characteristic of distortion in the radio frequency circuit based on the feedback signal.
2. The wireless communication system according to claim 1 , wherein
the second processor is configured to
receive a first known signal transmitted from the wireless device via the optical transmission line, and
stop processing of updating the distortion compensation coefficient when an error is detected in the first known signal.
3. The wireless communication system according to claim 1 , wherein
the second processor is configured to
transmit a second known signal to the wireless device via the optical transmission line,
calculate round-trip time on a basis of transmission timing of the second known signal and reception timing of a return signal transmitted from the wireless device in response to the second known signal, and
correct delay time in the first processing on a basis of the round-trip time.
4. The wireless communication system according to claim 1 , wherein
the first processor is configured to
execute first count processing, and
the second processor is configured to
execute second count processing,
output a frame timing signal in the baseband processing device based on the second count processing, and
correct the second count processing based on the first count processing.
5. The wireless communication system according to claim 4 , wherein
the second processor is configured to transmit a count value in the second count processing to the wireless device.
6. A baseband processing device configured to transmit a data signal to a wireless device via an optical transmission line and receive a feedback signal according to an output signal generated through amplification of the data signal in the wireless device from the wireless device via the optical transmission line, the baseband processing device comprising:
a memory; and
a processor coupled to the memory and configured to
receive the feedback signal from the wireless device, and
execute first processing of multiplying the data signal by a distortion compensation coefficient corresponding to an inverse characteristic of distortion in a wireless frequency circuit on a basis of the feedback signal.
7. The baseband processing device according to claim 6 , wherein
the processor is configured to
receive a first known signal transmitted from the wireless device via the optical transmission line, and
stop processing of updating the distortion compensation coefficient when an error is detected in the first known signal.
8. The baseband processing device according to claim 6 , wherein
the processor is configured to
transmit a second known signal to the wireless device via the optical transmission line,
calculate round-trip time on a basis of transmission timing of the second known signal and reception timing of a return signal transmitted from the wireless device in response to the second known signal, and
correct delay time in the first processing on a basis of the round-trip time.
9. The baseband processing device according to claim 6 , wherein
the wireless device execute first count processing, and
the processor is configured to
execute second count processing,
output a frame timing signal in the baseband processing device based on the second count processing, and
correct the second count processing based on the first count processing.
10. The baseband processing device according to claim 9 , wherein
the processor is configured to transmit a count value in the second count processing to the wireless device.
11. A wireless device configured to receive a data signal from a baseband processing device via an optical transmission line and carry out wireless transmission of an output signal obtained by amplifying the data signal, the wireless device comprising:
a radio frequency circuit configured to amplify the data signal to generate the output signal;
a memory; and
a processor coupled to the memory and configured to
generate a feedback signal according to the output signal generated by the radio frequency circuit, and
transmit the feedback signal to the baseband processing device via the optical transmission line.
12. The wireless device according to claim 11 , wherein
the baseband processing device execute first count processing, and
the processor is configured to
execute second count processing,
output a frame timing signal in the wireless device based on the second count processing, and
correct the second count processing based on the first count processing.
13. The wireless device according to claim 11 , wherein
the processor is configured to
execute count processing,
output a frame timing signal in the wireless device based on the second count processing, and
transmit a counting value of the count processing to the baseband processing device via the optical transmission line.
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US15/418,267 US10020887B2 (en) | 2014-10-16 | 2017-01-27 | Wireless communication system, baseband processing device, and wireless device |
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JP2014212086A JP2016082402A (en) | 2014-10-16 | 2014-10-16 | Baseband processing device, radio device and radio communication system |
JP2014-212086 | 2014-10-16 |
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US15/418,267 Expired - Fee Related US10020887B2 (en) | 2014-10-16 | 2017-01-27 | Wireless communication system, baseband processing device, and wireless device |
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JP2016082402A (en) | 2016-05-16 |
US10020887B2 (en) | 2018-07-10 |
US20170141850A1 (en) | 2017-05-18 |
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