CN111815927A - Signal transmission system and signal transmission method - Google Patents
Signal transmission system and signal transmission method Download PDFInfo
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- CN111815927A CN111815927A CN202010486789.1A CN202010486789A CN111815927A CN 111815927 A CN111815927 A CN 111815927A CN 202010486789 A CN202010486789 A CN 202010486789A CN 111815927 A CN111815927 A CN 111815927A
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Abstract
The application provides a signal transmission system for indoor signal covers, signal transmission system includes baseband processing unit, antenna element, RoC-RRU unit and LAN cable, antenna element includes local antenna element and distributed antenna element, distributed antenna element includes radio frequency front end unit and first radio access unit, RoC-RRU unit includes radio frequency remote unit and second radio access unit, baseband processing unit with the radio frequency remote unit is connected and is carried out the information interaction, local antenna element with the radio frequency remote unit is connected and is carried out the information interaction, LAN cable one end is passed through second radio access unit with the radio frequency remote unit is connected, and the other end passes through first radio access unit with the radio frequency front end unit is connected and is carried out the information interaction. The application also provides a signal transmission method. By the method and the device, the laying cost and the base station cost can be reduced on the premise of realizing high signal coverage.
Description
Technical Field
The present application relates to the field of signal processing technologies, and in particular, to a signal transmission system and a signal transmission method.
Background
With the emergence of various broadband applications such as smart homes and AR/VR, more and more mobile communications are in the room. When a communication operator (such as mobile, universal or telecom) establishes a wireless access network, in addition to the cellular deployment of macro base stations outdoors, coverage problems of signals indoors (such as office buildings, houses, malls, hospitals, gymnasiums, schools, etc.) need to be considered.
Due to the characteristic of wide coverage of the macro base station, most macro base stations are deployed through optical fibers at present; the coverage area required by the indoor signal is relatively small, and the indoor signal coverage can be carried out through the micro base station. For the micro base station, if signal coverage is still performed by means of optical fiber deployment, optical fibers need to be deployed indoors and outdoors, which greatly increases the cost of the base station and the cost of wiring.
Therefore, there is a need to provide an indoor signal coverage method, which can reduce the cost of base stations and the cost of wiring while ensuring the signal coverage efficiency.
Disclosure of Invention
In view of the above, it is desirable to provide a signal transmission system and a signal transmission method, which can reduce the layout of optical fibers and thus reduce the cost of base stations and the cost of wiring while ensuring the coverage.
A first aspect of embodiments of the present application provides a signal transmission system for indoor signal coverage, the signal transmission system comprising a baseband processing unit, an antenna unit, RoC-RRU unit and LAN cable, the antenna unit comprises a local antenna unit and a distributed antenna unit, the distributed antenna unit comprises a radio frequency front end unit and a first radio access unit, the RoC-RRU unit includes a radio remote unit and a second radio access unit, the baseband processing unit is connected with the remote radio unit for information interaction, the local antenna unit is connected with the remote radio unit for information interaction, one end of the LAN cable is connected with the remote radio unit through the second radio access unit, and the other end of the LAN cable is connected with the radio frequency front end unit through the first radio access unit for information interaction.
Further, in the above signal transmission system provided in this embodiment of the present application, the distributed antenna unit is installed in each floor of a building, and the distributed antenna unit is configured to receive a cable subcarrier transmitted by the LAN cable and convert the cable subcarrier into an RF signal to be covered in the floor.
Further, in the signal transmission system provided in this embodiment of the present application, the local antenna unit is installed on the RoC-RRU unit, and is configured to receive an IF signal transmitted by a radio remote unit in the RoC-RRU unit, and perform signal processing on the IF signal to obtain an RF signal that covers outdoors.
Further, in the above signal transmission system provided in the embodiment of the present application, the radio frequency front end unit includes a first filtering module, a first frequency conversion module, a power amplification module, and a low noise amplification module, where the first frequency conversion module is connected to the first filtering module, the first frequency conversion module is further connected to the power amplification module and/or the low noise amplification module, the first filtering module is configured to pass a signal of a target frequency, the first frequency conversion module is configured to convert an IF signal and an RF signal, and the power amplification module and the low noise amplification module are configured to perform power shaping on an output/input signal.
Further, in the signal transmission system provided in the embodiment of the present application, the rf front-end unit further includes a first analog multiplexing module, and the first analog multiplexing module is configured to collect an output signal of the first filtering module in an uplink and generate a composite signal.
Further, in the above signal transmission system provided in this embodiment of the present application, the remote radio unit includes a D/a conversion module and/or an a/D conversion module, a second frequency conversion module, a second filtering module and a second analog multiplexing module, the D/a conversion module and/or the a/D conversion module is configured to be connected to the second frequency conversion module, the second frequency conversion module is configured to be connected to the second filtering module and the second analog multiplexing module, the D/a conversion module and/or the a/D conversion module is configured to perform conversion between a digital signal and an analog signal, the second frequency conversion module is configured to perform up-conversion processing and/or down-conversion processing on the signal, the second filtering module is configured to pass a signal at a target frequency, the second analog multiplexing module is used for acquiring the output signal of the second filtering module and generating a composite signal.
Further, in the signal transmission system provided in the embodiment of the present application, the signal transmission system further includes a signal mapping module, where the signal mapping module is configured to divide the mid-band of the LAN cable into preset bands and map the composite signal to a target band.
Further, in the signal transmission system provided in the embodiment of the present application, the signal transmission system further includes an analog loop module, and the analog loop module is configured to implement dynamic switching of uplink and downlink paths.
A second aspect of the embodiments of the present application further provides a signal transmission method, which applies any one of the signal transmission systems described above, where the signal transmission method includes:
the baseband processing unit sends out a baseband signal to the RoC-RRU unit;
the RoC-RRU unit receives the baseband signal and processes the baseband signal to obtain an IF signal;
the RoC-RRU unit transmits the IF signal to the local antenna unit and the distributed antenna unit respectively;
the local antenna unit processes the IF signal to obtain an RF signal and covers the RF signal outside the building;
and the distributed antenna unit processes the IF signal to obtain an RF signal and covers the RF signal into a building.
Further, in the foregoing signal transmission method provided in this embodiment of the present application, when the RoC-RRU unit transmits the IF signal to the distributed antenna unit, the method further includes:
the RoC-RRU unit converts a number of the IF signals into a composite signal and transmits the composite signal to the distributed antenna unit over the LAN cable;
when the distributed antenna unit receives the composite signal, the composite signal is split into a plurality of IF signals again, the IF signals are subjected to signal processing to obtain an RF signal, and the RF signal is covered indoors.
The application provides a signal transmission system and a signal transmission method, wherein a local antenna unit is arranged outside a building for outdoor coverage, a distributed antenna unit is arranged on each floor in the building for indoor coverage, and centralized resources are used for indoor and outdoor service supply, so that the cost of a base station can be reduced; the RoC-RRU unit and the distributed antenna unit are connected through the LAN cable instead of optical fibers, so that the wiring cost and the base station cost can be reduced under the condition of ensuring the signal coverage rate.
Drawings
Fig. 1 is a schematic structural diagram of a signal transmission system according to an embodiment of the present application.
Fig. 2 is a functional diagram of a signal transmission system according to an embodiment of the present application.
Fig. 3 (a) is a schematic diagram of a signal mapping provided in an embodiment of the present application.
Fig. 3 (b) is a schematic diagram of another signal mapping provided in the embodiment of the present application.
Fig. 4 is a flowchart of a signal transmission method according to an embodiment of the present application.
Fig. 5 is a diagram of simulation results based on a signal transmission system according to an embodiment of the present application.
Fig. 6 is a comparison diagram of a signal mapping method according to an embodiment of the present application and the prior art.
Description of reference numerals:
Detailed Description
In order that the above objects, features and advantages of the present application can be more clearly understood, a detailed description of the present application will be given below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth to provide a thorough understanding of the present application, and the described embodiments are a part, but not all, of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
The application provides a signal transmission system for indoor signal covers, signal transmission system includes baseband processing unit, antenna element, RoC-RRU unit and LAN cable, antenna element includes local antenna element and distributed antenna element, distributed antenna element includes radio frequency front end unit and first radio access unit, RoC-RRU unit includes radio frequency remote unit and second radio access unit, baseband processing unit with the radio frequency remote unit is connected and is carried out the information interaction, local antenna element with the radio frequency remote unit is connected and is carried out the information interaction, LAN cable one end is passed through second radio access unit with the radio frequency remote unit is connected, and the other end passes through first radio access unit with the radio frequency front end unit is connected and is carried out the information interaction.
The application provides a signal transmission system, which can reduce the cost of a base station by arranging a local antenna unit outside a building for outdoor coverage, arranging a distributed antenna unit on each floor in the building for indoor coverage and concentrating resources for indoor and outdoor service supply; the RoC-RRU unit and the distributed antenna unit are connected through the LAN cable instead of optical fibers, so that the wiring cost and the base station cost can be reduced under the condition of ensuring the signal coverage rate.
Referring to fig. 1 and fig. 2, the signal transmission system 100 can be applied to a micro base station for covering indoor antenna signals. The signal transmission system 100 comprises a baseband processing unit (not shown), an antenna unit 10, RoC-RRU unit 20 and a LAN cable 30. The antenna unit 10 includes a Local Antenna Unit (LAU)11 and a Distributed Antenna Unit (DAU) 12. The baseband processing unit and the RoC-RRU unit 20 are connected through an optical fiber 50 for signal interaction, the RoC-RRU unit 20 is connected with the antenna unit 10 for signal interaction, the RoC-RRU unit 20 is connected with the local antenna unit 11, the local antenna unit receives the signal transmitted by the RoC-RRU unit 20, performs signal processing on the transmitted signal to obtain an RF signal, and covers the RF signal outdoors; the RoC-RRU unit 20 is connected to the distributed antenna unit 12 via the LAN cable 30, and the distributed antenna unit 12 receives the cable sub-carriers transmitted by the LAN cable 30 and converts the cable sub-carriers into RF signals to be covered in the floor.
The baseband processing unit is configured to transmit a baseband signal (BB signal, original electrical signal sent by an information source without modulation), and specifically, the baseband processing unit is connected to the RoC-RRU unit 20 through an optical fiber 50, and transmits the received baseband signal to the optical fiber 50, and transmits the baseband signal to the remote radio unit 21 in the RoC-RRU unit 20 through the optical fiber 50.
The antenna unit 10 includes a local antenna unit 11 and a distributed antenna unit 12, and the local antenna unit 11 is installed on the RoC-RRU unit 20, and is configured to receive the IF signal transmitted by the RoC-RRU unit 20, and perform signal processing on the IF signal to obtain an RF signal that covers the outdoor. The distributed antenna unit 12 is installed in each floor of the building, and the distributed antenna unit 12 is configured to receive the cable subcarriers transmitted by the LAN cable 30 and convert the cable subcarriers into RF signals to be covered in the floor. By laying the local antenna unit 11 outside the building for outdoor coverage, the distributed antenna unit 12 on each floor within the building for indoor coverage, and concentrating resources for indoor and outdoor service supply, base station cost can be reduced.
The distributed antenna unit 12 includes a radio frequency front end unit 121, a first radio access unit (not shown), and an antenna array 123, where the radio frequency front end unit 121 is connected to the first radio access unit, and the radio frequency front end unit 121 is further connected to the antenna array 123. The first radio access unit is configured to receive a cable subcarrier output by the LAN cable 30, and transmit the cable subcarrier to the radio frequency front end unit 121, where the radio frequency front end unit 121 is configured to perform signal processing on the cable subcarrier to obtain an RF signal, and transmit the RF signal through the antenna array 123 for indoor signal coverage.
The RF front-end unit 121 includes a first filtering module 1211, a first frequency conversion module 1212, a power amplification module 1213, and a low noise amplification module 1214, where the first frequency conversion module 1212 is connected to the first filtering module 1211, the first frequency conversion module 1212 is further connected to the power amplification module 1213 and/or the low noise amplification module 1214, the first filtering module 1211 is configured to pass a signal of a target frequency, the first frequency conversion module 1212 is configured to convert an IF signal and an RF signal, and the power amplification module 1213 and the low noise amplification module 1214 are configured to perform power shaping on an output/input signal.
The rf front end unit 121 further includes a first analog multiplexing module 1215, and the first analog multiplexing module 1215 is configured to collect the output signal of the first filtering module 1211 in an uplink of signal transmission and generate a composite signal.
Illustratively, for the downlink of signal transmission, the number of antennas is assumed to be 8 (i.e., N)18), the achievable channel bandwidth f on the LAN cablemaxAt 400MHz, the distance between the RoC-RRU unit 20 and the distributed antenna unit 12 is 100m, and the spectrum width of each antenna signal is 50MHz (i.e., f)RF50 MHz). When the first radio access unit receives the cable sub-carriers output from the LAN cable 30, a signal feeding mechanism for feeding the cable sub-carriers into a preset filter bank is invoked in order to recover the IF signal of the antenna. The first filtering module 1211 is configured to perform filtering processing on the recovered IF signal to obtain an IF signal of a target frequency, transmit the IF signal of the target frequency to the first frequency conversion module 1212, call the first frequency conversion module 1212 to up-convert the IF signal of the target frequency into an RF signal, transmit the RF signal to the power amplification module 1213, call the power amplification module 1213 to perform power amplification processing on the RF signal so as to meet an antenna signal coverage requirement, transmit the RF signal after the power amplification processing to the antenna array 123 to be transmitted, and perform indoor signal coverage. Wherein the preset filter bank is the same as the filter bank in the RoC-RRU unit 20, and the signal transmission efficiency can be improved by feeding the cable sub-carriers into the same filter bank as in the RoC-RRU unit 20.
In an uplink of signal transmission, when the antenna array 123 receives an RF signal transmitted by a terminal, the antenna array 123 transmits the RF signal to the low-noise amplification module 1214 for low-noise amplification to obtain an RF signal meeting a transmission requirement, and transmits the RF signal meeting the transmission requirement to the first frequency conversion module 1212, where the first frequency conversion module 1212 is configured to perform down-conversion on the RF signal to obtain an IF signal, and transmit the IF signal to the first filtering module 1211 for filtering to obtain an IF signal of a target frequency. In one embodiment, when the number of the antennas is multiple, the number of the corresponding antenna signals is also multiple, that is, multiple processors are required to process the antenna signals in parallel to improve the signal processing efficiency. The first analog multiplexing module 1215 is called to collect the IF signals of the target frequencies transmitted from the plurality of filters and generate a composite signal to transmit the composite signal through one LAN cable 30. It should be noted that the lines between the uplink and the downlink in fig. 2 do not intersect.
The local antenna unit 11 includes a second radio frequency front end unit (not shown in the figure) and a second antenna array (not shown in the figure), where the second radio frequency front end unit is configured to receive the IF signal transmitted by the RoC-RRU unit 20, process the IF signal to obtain an RF signal, and transmit the RF signal through the second antenna array to perform outdoor signal coverage. In one embodiment, the local antenna unit 11 and the RoC-RRU unit 20 are connected by an optical fiber 50. In other embodiments, the local antenna unit 11 and the RoC-RRU unit 20 are connected by LAN cables.
The RoC-RRU unit 20 is a new device for integrating the radio remote unit 21 and the second radio access unit 22, and the RoC-RRU unit 20 can be installed on the top of a building. The remote radio unit 21 is connected to the baseband processing unit for signal interaction, the remote radio unit 21 is connected to the local antenna unit 11 for signal interaction, and the remote radio unit 21 is connected to the LAN cable 30 through the second radio access unit 22 for signal transmission.
The radio remote unit 21 includes a CPRI interface module 210, a D/a conversion module 211 and/or an a/D conversion module 212, a second frequency conversion module 213, a second filtering module 214, and a second analog multiplexing module 215, where the CPRI interface module 210 is connected to the D/a conversion module 211 and/or the a/D conversion module 212 for signal interaction, the D/a conversion module 211 and/or the a/D conversion module 212 is used for signal interaction connected to the second frequency conversion module 213, the second frequency conversion module 213 is used for signal interaction connected to the second filtering module 214 and the second analog multiplexing module 215, and the CPRI interface module 210 is used as a connection interface with the baseband processing unit; the D/a conversion module 211 and/or the a/D conversion module 212 are configured to perform conversion between a digital signal and an analog signal, the second frequency conversion module 213 is configured to perform up-conversion processing and/or down-conversion processing on the signal, the second filtering module 214 is configured to pass a signal of a target frequency, and the second analog multiplexing module 215 is configured to collect an output signal of the second filtering module 214 and generate a composite signal.
Illustratively, for the downlink of signal transmission, the baseband signal transmitted by the baseband processing unit is received (for example, the baseband signal is received by the CPRI interface module 210), and the baseband signal is transmitted to the D/a conversion module 211, and the D/a conversion module 211 is invoked to convert the baseband signal in digital form into the baseband signal in analog form (denoted as x:)1To x8) And transmits the analog baseband signal to the second frequency conversion module 213, and invokes the second frequency conversion module 213 to up-convert the analog baseband signal into an IF signal (the up-conversion frequency in the IF frequency domain is denoted as f)1To f8) And transmits the IF signal to the second filtering module 214, and invokes the second filtering module 214 to filter the IF signal to obtain the IF signal with the target frequency. In one embodiment, when the number of the antennas is multiple, the number of the corresponding antenna signals is also multiple, that is, multiple processors are required to process the antenna signals in parallel to improve the signal processing efficiency. The second analog multiplexing module 215 is called to collect IF signals in a plurality of filters and convert the plurality of IF signals into a composite signal to transmit the composite signal through one LAN cable 30.
For the uplink of signal transmission, when the second radio access unit 22 receives the composite signal (i.e. cable sub-carrier) transmitted by the LAN cable 30, a signal feeding mechanism is invoked, which is also used to feed the cable sub-carrier into a preset filter bank to recover the IF signal of the antenna. The second filtering module 214 is configured to perform filtering processing on the IF signal to obtain an IF signal of a target frequency, transmit the IF signal of the target frequency to the second frequency conversion module 213, call the second frequency conversion module 213 to down-convert the IF signal into a baseband signal, and transmit the baseband signal to the a/D conversion module 212, call the a/D conversion module 212 to convert the baseband signal of an analog form into a baseband signal of a digital form, and transmit the baseband signal of the digital form to the baseband signal transmitted by the baseband processing unit (for example, transmit the baseband signal of the digital form through the CPRI interface module 210).
The LAN cable 30 is a local area network cable, the LAN cable 30 may be placed in a cable distribution box 31, and the LAN cable 30 is arranged in order by the cable distribution box 31. In one embodiment, the LAN cable may be a copper cable in the form of a twisted pair in terms of signal transmission efficiency and wiring cost. In other embodiments, the LAN cable may also be a cable of other materials, and is not limited herein. The two ends of the LAN cable are respectively connected to the first radio access unit and the second radio access unit 22, the LAN cable 30 connected to the first radio access unit is connected to the distributed antenna unit 12 for signal interaction, and the LAN cable 30 connected to the second radio access unit 22 is connected to the remote radio unit 21 in the RoC-RRU unit 20 for signal interaction.
The signal transmission system 100 further includes a signal mapping module (not shown) for dividing the frequency band in the LAN cable 30 into preset frequency bands and mapping the composite signal to a target frequency band. It will be appreciated that the cable subcarriers in the LAN cable may be divided into different frequency bands, e.g., high frequency, intermediate frequency, and low frequency, depending on the frequency. Cable sub-carriers of different frequency bands may accommodate antenna signals of different spectral efficiencies. Preferably, for antenna signals with higher spectral efficiency, the antenna signals can be mapped to the low frequency band of the cable subcarriers; for antenna signals with lower spectral efficiency, they can be mapped to the high band of the cable subcarriers.
Referring to fig. 3 (a) and (b), fig. 3 (a) is a signal mapping diagram according to an embodiment of the present disclosure, and fig. 3 (b) is another signal mapping diagram according to an embodiment of the present disclosure. (a) FIG. and (b) is a diagram showing 8 antenna signals A for supporting 50MHz1To A8The capacity distribution of the number of bits per second of the LAN cable 30 of (a) ranges from 8bps/Hz to 2bps/Hz, and the horizontal axes of the (a) and (b) graphs indicate the frequencies of the cable subcarriers, ranging from 0MHz to 500 MHz; the vertical axis represents the spectral efficiency of the antenna signal, ranging from 2bps/Hz to 8 bps/Hz.
As shown in the diagram (a), the antenna signals with different spectral efficiencies are directly distributed to different frequency bands of the cable subcarrier, and the cable capacity at 300-400MHz frequency is insufficient, so that A cannot be accommodated7And A8Two antenna signals, resulting in poor overall transmission quality of the antenna. As shown in (b), if the signal mapping module provided in the present application is used to perform signal mapping between RF signals and cable subcarriers, the cable subcarriers can accommodate 8 antenna signals, thereby ensuring signal transmission quality. Illustratively, for antenna signal A with higher spectral efficiency1、A7、A8It may be mapped to the low band of the cable sub-carriers; for an antenna signal a with moderate spectral efficiency2、A4It can be mapped to the mid-band of the cable sub-carrier; for antenna signal a with lower spectral efficiency3、A5、A6It may be mapped to the high band of cable subcarriers.
Preferably, since there is a mapping relationship between the antenna signal and the cable subcarrier, the first filtering module 1211, the first frequency conversion module 1212, the power amplification module 1213, and the low noise amplification module 1214 in the distributed antenna unit 12 may be set as virtual devices, and by setting the above elements as virtual devices, it is possible to reduce the control complexity of the distributed antenna unit 12 and reduce the hardware cost of the distributed antenna unit 12.
The signal transmission system 100 further includes an analog loop module 40, where the analog loop module 40 is configured to implement dynamic switching between uplink and downlink paths, and in particular, implement dynamic switching between uplink and downlink paths in the distributed antenna unit 12. One antenna may be used for signal transmission as a signal path for uplink and downlink in consideration of deployment cost and wiring cost of the base station. In this case, the RF signal on the transmission path of the RF front-end unit 121 in the distributed antenna unit 12 may leak to the reception path of the same antenna, so that the RF front-end unit 121 suffers from self-interference. Thus, the present application avoids the effects of self-interference by isolating the received RF signal from the transmitted RF signal. Specifically, frame timing information of the received RF signal and the transmitted RF signal is acquired in real time by the analog loop module 40, and an uplink path and a downlink path are determined according to the frame timing information. The frame timing information is stored in the RoC-RRU unit 20, and the RoC-RRU unit 20 transmits the frame timing information to the distributed antenna unit 12 in real time, so that the analog loop module 40 acquires the frame timing information from the distributed antenna unit 12 in real time. In one embodiment, the RoC-RRU unit 20 transmits the frame timing information via a low frequency signal on the cable sub-carrier of the LAN cable 30 to ensure real-time performance of the frame timing information.
The present application provides a signal transmission system 100, which can reduce the base station cost by laying a local antenna unit 11 outside a building for outdoor coverage, laying a distributed antenna unit 12 on each floor inside the building for indoor coverage, and concentrating resources for indoor and outdoor service supply; connecting the RoC-RRU unit 20 with the distributed antenna unit 12 through the LAN cable 30 instead of optical fiber can reduce the wiring cost and the base station cost while ensuring the signal coverage.
Referring to fig. 4, fig. 4 is a flowchart of a signal transmission method according to an embodiment of the present application. The signal transmission method is applied to the signal transmission system 100, taking a downlink of signal transmission as an example (the signal transmission method of the uplink is similar to that of the downlink, and the description of the signal transmission method of the uplink is omitted here), specifically, the signal transmission method includes:
and S41, the baseband processing unit sends out a baseband signal to the RoC-RRU unit.
The baseband processing unit may transmit baseband signals to the remote radio unit 21 in the RoC-RRU unit 20 through the optical fiber 50.
And S42, the RoC-RRU unit receives the baseband signal and processes the baseband signal to obtain an IF signal.
In one embodiment, the radio remote unit 21 performs signal processing on the baseband signal, where the signal processing includes one or more of the following: d/a conversion processing, frequency conversion processing, filter processing, and analog multiplexing processing. Specifically, the radio remote unit 21 converts a baseband signal in a digital form into a baseband signal in an analog form; then, frequency conversion (for example, up-conversion processing) is performed on the baseband signal in the analog form to obtain an IF signal; then, filtering the IF signal to obtain an IF signal of a target frequency; and finally, carrying out composite processing on the multiple paths of IF signals to obtain composite signals.
And S43, the RoC-RRU respectively transmits the IF signal to the local antenna unit and the distributed antenna unit.
In one embodiment, the remote radio unit 21 and the local antenna unit 11 may be connected by the LAN cable 30. In other embodiments, the remote radio unit 21 and the local antenna unit 11 may be connected through the optical fiber 50. The RoC-RRU unit 20, the remote radio unit 21 transmits the IF signal to the local antenna unit 11, and the local antenna unit performs outdoor signal coverage.
The remote radio unit 21 is connected to the distributed antenna unit 12 through the LAN cable 30, and the distributed antenna unit 12 receives signals transmitted by the LAN cable 30 to perform indoor signal coverage.
In one embodiment, when the RoC-RRU unit 20 transmits the IF signal to the distributed antenna unit 12, the method further comprises: the RoC-RRU unit 20 converts several of the IF signals into a composite signal and transmits the composite signal over the LAN cable 30 to the distributed antenna unit 12; when receiving the composite signal, the distributed antenna unit 12 splits the composite signal into a plurality of IF signals, performs signal processing on the plurality of IF signals to obtain an RF signal, and covers the RF signal indoors.
Preferably, when transmitting signals through the LAN cable 30, the mid-band of the LAN cable 30 may be divided into preset frequencies, and the composite signal may be mapped to a target band. For example, signals in the composite signal are sorted according to the spectral efficiency, and for an antenna signal with higher spectral efficiency, the antenna signal can be mapped to a low frequency band of a cable subcarrier; for antenna signals with lower spectral efficiency, they can be mapped to the high band of the cable subcarriers. By mapping the composite signal to the optimal frequency band of the cable subcarrier, the transmission quality of the antenna signal can be ensured, and the problem that the antenna signal cannot be transmitted through the cable subcarrier is avoided.
Preferably, the method further comprises: a real-time communication mechanism is established between the distributed antenna unit 12 and the RoC-RRU unit. The real-time communication mechanism is used for activating preset equipment along a signal path in the signal transmission process, wherein the preset equipment comprises a filter, a frequency converter, a power amplifier and the like. By establishing a real-time communication mechanism, the signal transmission efficiency can be further improved.
And S44, the local antenna unit processes the IF signal to obtain an RF signal and covers the RF signal outside the building.
In one embodiment, the local antenna unit 11 performs signal processing on the IF signal, the signal processing including one or more of: filtering, frequency conversion and power amplification. Specifically, the second rf front-end unit in the local antenna unit 11 is configured to perform filtering processing on the received IF signal to obtain an IF signal of a target frequency; performing frequency conversion processing (for example, up-conversion processing) on the IF signal of the target frequency to obtain an RF signal; performing power amplification processing on the RF signal to obtain an RF signal which is transmitted by an antenna; and finally, transmitting the RF signal to the second antenna array, and transmitting the RF signal by the second antenna array to finish covering the RF signal outside the building.
And S45, the distributed antenna unit processes the IF signal to obtain an RF signal, and covers the RF signal into a building.
In one embodiment, the distributed antenna unit 12 performs signal processing on the IF signal to obtain an RF signal, where the signal processing includes one or more of the following: filtering, frequency conversion and power amplification. Specifically, the radio frequency front end unit 121 in the distributed antenna unit 12 is configured to perform filtering processing on the received IF signal to obtain an IF signal of a target frequency; performing frequency conversion processing (for example, up-conversion processing) on the IF signal of the target frequency to obtain an RF signal; performing power amplification processing on the RF signal to obtain an RF signal which is transmitted by an antenna; finally, the RF signal is transmitted to the antenna array 123, and the antenna array 123 transmits the RF signal, thereby completing the coverage of the RF signal into the building.
In an embodiment, considering the deployment cost and the wiring cost of the base station, for the uplink and the downlink in the distributed antenna unit 12, one antenna may be used as a signal path for signal transmission. And in order to avoid the problem that the RF signal in the transmission path of the RF front-end unit 121 in the distributed antenna unit 12 may leak to the reception path of the same antenna, so that the RF front-end unit 121 suffers from self-interference, the analog loop module 40 may be invoked to acquire frame timing information of the received RF signal and the transmitted RF signal in real time, and determine the uplink path and the downlink path according to the frame timing information. By dynamically switching the path for receiving the RF signal and the road condition for transmitting the RF signal, the problem that the radio frequency front end unit 121 is self-interfered can be avoided on the basis of reducing the cost of the base station and the wiring.
According to the signal transmission method, the local antenna units are arranged outside the building for outdoor coverage, the distributed antenna units are arranged on each floor in the building for indoor coverage, and centralized resources are used for indoor and outdoor service supply, so that the base station cost can be reduced; the RoC-RRU unit and the distributed antenna unit are connected through the LAN cable instead of optical fibers, so that the wiring cost and the base station cost can be reduced under the condition of ensuring the signal coverage rate.
Referring to fig. 5-6 together, fig. 5 is a graph showing the relationship between the frequency of the LAN cable and the average spectral efficiency of the antenna signal. Fig. 6 shows a comparison of the signal mapping method provided in the present application with the prior art. Fig. 5 shows the frequency of three LAN cables 30 versus the average spectral efficiency of the antenna signal for LAN cable 30 lengths of 100m, 150m and 200 m. As shown in fig. 5, the optimal spectrum efficiency of the prior art is in the range of 2-8bps/Hz (the dotted lines from left to right in the figure sequentially show the simulation results of the prior art at the lengths of 200m, 150m and 100m of the LAN cable 30), and the signal transmission system 100 provided by the present application is limited to 8bps/Hz (the solid lines show the simulation results at the lengths of 200m, 150m and 100m of the LAN cable 30 provided by the present application, and the three solid lines coincide), which will reduce the bandwidth of signal transmission. For a 100m-200m length of LAN cable 30, the total throughput can be reduced by 2.57% to 25.13% compared to the prior art, and thus a smaller number of antennas is required, thereby reducing the base station cost and the wiring cost.
The signal transmission system 100 provided by the present application can satisfy 5G general requirements in terms of time delay, peak data rate, and peak spectral efficiency. For the downlink, 5G eMBB services need to reach peak data rates and peak spectral efficiencies of 20Gbps and 30 bps/Hz; for the uplink, peak data rates and peak spectral efficiencies of 10Gbps and 15bps/Hz need to be achieved. On the user data plane, the latency requirement along the forward link in both the uplink and downlink directions is 4ms, and the URLLC-based 5G application further imposes a delay of 0.5ms along the forward link.
First, in order to ensure that each antenna can achieve a spectrum efficiency of 8bps/Hz, the signal transmission system 100 of the present application can use 2T4R (i.e., 2 transmit antennas and 4 receive antennas) to achieve 30bps/Hz for the downlink and 15bps/Hz for the uplink. Second, from the total spectral width of each twisted pair, we can calculate how many LAN cables 30 are needed to meet peak data rate requirements. For example, with a cable length less than 100m, two LAN cables 30, each having a twisted pair spectral width of 320MHz and a spectral efficiency of 8bps/Hz, are required to provide a peak data rate of 20 Gbps. If the cable length is 200m, the spectral width of each twisted pair will become 80MHz and at least 8 LAN cables 30 will be required to meet the peak data rate requirements. Furthermore, 5 GNRs are designed specifically for massive MIMO air interfaces, where the number of antennas in an antenna array must be 32 or more. Here, for the frequency band below 6GHz in 5GNR, the maximum air bandwidth of a single antenna is 100MHz, and assuming that the transmission bandwidth of each twisted pair is 300MHz (as shown in fig. 6), i.e., the RRU is 100m away from the DAU, 3 LAN cables 30 are needed to transmit the signals from 36 antennas. Furthermore, considering that the fronthaul link based on the CPRI/eccri interface generates delays of 25 μ sec and 500 μ sec for URLLC and large delay applications, respectively, the end-to-end latency of the fronthaul link increases for the signal transmission system 100 provided herein. In summary, the signal transmission system 100 provided by the present application can satisfy the 5G service requirement.
In the several embodiments provided in the present invention, it should be understood that the disclosed computer apparatus and method may be implemented in other ways. For example, the system embodiments described above are merely illustrative, and for example, the division of the modules is only one logical functional division, and other divisions may be realized in practice.
It will be evident to those skilled in the art that the embodiments of the present invention are not limited to the details of the foregoing illustrative embodiments, and that the embodiments of the present invention are capable of being embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the embodiments being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Several of the units, modules or means recited in the system, apparatus or computer device claims may also be implemented by one and the same unit, module or means in software or hardware.
Although the embodiments of the present invention have been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the embodiments of the present invention.
Claims (10)
1. A signal transmission system for indoor signal coverage, characterized in that the signal transmission system comprises a baseband processing unit, an antenna unit, RoC-RRU unit and LAN cable, the antenna unit comprises a local antenna unit and a distributed antenna unit, the distributed antenna unit comprises a radio frequency front end unit and a first radio access unit, the RoC-RRU unit includes a radio remote unit and a second radio access unit, the baseband processing unit is connected with the remote radio unit for information interaction, the local antenna unit is connected with the remote radio unit for information interaction, one end of the LAN cable is connected with the remote radio unit through the second radio access unit, and the other end of the LAN cable is connected with the radio frequency front end unit through the first radio access unit for information interaction.
2. The signal transmission system of claim 1, wherein the distributed antenna unit is installed in each floor of a building, and the distributed antenna unit is configured to receive cable subcarriers transmitted by the LAN cable and convert the cable subcarriers into RF signals to be overlaid on the floor.
3. The signal transmission system of claim 1, wherein the local antenna unit is installed in the RoC-RRU unit, and configured to receive an IF signal transmitted by a remote radio unit in the RoC-RRU unit, and perform signal processing on the IF signal to obtain an RF signal covering outdoors.
4. The signal transmission system according to claim 1, wherein the RF front-end unit comprises a first filtering module, a first frequency conversion module, a power amplification module and a low noise amplification module, the first frequency conversion module is connected to the first filtering module, the first frequency conversion module is further connected to the power amplification module and/or the low noise amplification module, the first filtering module is configured to pass signals of a target frequency, the first frequency conversion module is configured to convert IF signals and RF signals, and the power amplification module and the low noise amplification module are configured to perform power shaping on output/input signals.
5. The signal transmission system of claim 4, wherein the RF front-end unit further comprises a first analog multiplexing module configured to collect the output signal of the first filtering module and generate a composite signal in an uplink.
6. The signal transmission system according to claim 1, wherein the remote radio unit comprises a D/a conversion module and/or a/D conversion module, a second frequency conversion module, a second filtering module and a second analog multiplexing module, the D/a conversion module and/or the a/D conversion module is configured to be connected to the second frequency conversion module, the second frequency conversion module is configured to be connected to the second filtering module and the second analog multiplexing module, the D/a conversion module and/or the a/D conversion module is configured to perform conversion between digital signals and analog signals, the second frequency conversion module is configured to perform up-conversion processing and/or down-conversion processing on the signals, and the second filtering module is configured to pass signals of a target frequency, the second analog multiplexing module is used for acquiring the output signal of the second filtering module and generating a composite signal.
7. The signal transmission system according to claim 6, further comprising a signal mapping module configured to divide the LAN cable middle frequency band into preset frequency bands and map the composite signal to a target frequency band.
8. The signal transmission system of claim 1, further comprising an analog loop module for implementing dynamic switching of uplink and downlink paths.
9. A signal transmission method using the signal transmission system according to any one of claims 1 to 8, the signal transmission method comprising:
the baseband processing unit sends out a baseband signal to the RoC-RRU unit;
the RoC-RRU unit receives the baseband signal and processes the baseband signal to obtain an IF signal;
the RoC-RRU unit transmits the IF signal to the local antenna unit and the distributed antenna unit respectively;
the local antenna unit processes the IF signal to obtain an RF signal and covers the RF signal outside the building;
and the distributed antenna unit processes the IF signal to obtain an RF signal and covers the RF signal into a building.
10. The signal transmission method of claim 9, wherein when the RoC-RRU unit transmits the IF signal to the distributed antenna unit, the method further comprises:
the RoC-RRU unit converts a number of the IF signals into a composite signal and transmits the composite signal to the distributed antenna unit over the LAN cable;
when the distributed antenna unit receives the composite signal, the composite signal is split into a plurality of IF signals again, the IF signals are subjected to signal processing to obtain an RF signal, and the RF signal is covered indoors.
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