CN110958617A

CN110958617A - Signal transmission system and signal transmission method

Info

Publication number: CN110958617A
Application number: CN201911236246.8A
Authority: CN
Inventors: 周强; 刘光华; 杨宝义
Original assignee: Beijing Kaibo Wireless Technology Co Ltd
Current assignee: Beijing Kaibo Wireless Technology Co Ltd
Priority date: 2019-12-05
Filing date: 2019-12-05
Publication date: 2020-04-03
Anticipated expiration: 2039-12-05
Also published as: CN110958617B

Abstract

The embodiment of the application provides a signal transmission system and a signal transmission method, and relates to the field of communication. The signal transmission system comprises a main unit device, a far-end frequency conversion device and a coaxial network; the main unit device is used for carrying out up-conversion processing on each channel signal in the multi-channel digital baseband signal and combining the multi-channel intermediate frequency signals with different frequencies to obtain a first combined intermediate frequency signal; the coaxial network is used for transmitting the first combined intermediate frequency signal to the far-end frequency conversion equipment; and the far-end frequency conversion equipment is used for carrying out shunting processing on the received first combined intermediate frequency signal, carrying out up-conversion processing on each path of divided intermediate frequency signal to obtain a radio frequency signal of carrier frequency specified by an operator, and sending the multiple paths of radio frequency signals through an antenna. Similarly, the process is reversed in the signal receiving direction. The signal transmission system adopts a frequency division multiplexing mode, and can support the MIMO function under the condition that the existing coaxial network is not required to be upgraded.

Description

Signal transmission system and signal transmission method

Technical Field

The present application relates to the field of communications technologies, and in particular, to a signal transmission system and a signal transmission method.

Background

When a communication operator (such as mobile, universal or telecom) establishes a radio access network, in addition to the cellular deployment of macro base stations in the open air, coverage of signals in the indoor (such as office buildings, houses, shopping malls, hospitals, schools, and gymnasiums) needs to be considered. Different from an open outdoor place, due to the fact that various shelters and reflectors exist indoors, indoor signals can be covered without dead angles by densely deploying antennas. However, the one base station equipment for each antenna makes the whole project prohibitively expensive, and a Distributed Antenna System (DAS) is produced in order to reduce the cost of indoor coverage deployment.

The DAS system is a system that a feeder between a base station device and an antenna is extended, and a base station signal is uniformly distributed to a plurality of antenna units located at different places through passive devices such as a distributor and a directional coupler; and in the opposite direction, the signals received by each antenna unit are converged into the base station equipment through the original path of the coaxial network, so that the uniform coverage of the wireless signals in the indoor environment is realized. In this method, signals from feeder ports of the base station are connected to antennas at a plurality of positions via a coaxial network. The medium of transmission is coaxial cable. In the 2G and 3G era with low carrier frequency, the DAS system is widely used. By the 4G era, the coaxial network can be reluctantly responded after being upgraded and modified.

However, as the carrier frequency increases (e.g. 5G signal), the conventional DAS indoor solution has the following drawbacks: the original devices of the coaxial network generally do not support a new frequency band, and the original devices need to be upgraded and replaced when the carrier frequency is improved; at present, the DAS system is difficult to support MIMO (Multiple-Input Multiple-Output) function between the base station and the mobile terminal, and for example, when transmitting signals of the 2T2R base station, a set of coaxial network needs to be added.

Although alternatives have been developed after this that overcome the above drawbacks, such as solutions using fiber-optic remoting, solutions using digital chamber division. However, these solutions abandon the original transmission medium of the coaxial network, and replacing the transmission medium would bring about huge time and money costs.

In addition, the price of both the near-end and far-end devices of these alternatives is also expensive, which further increases the difficulty of deployment of wireless communication systems (such as 5G communication systems).

Disclosure of Invention

Embodiments of the present application provide a signal transmission system and a signal transmission method, which are used to solve the above technical drawbacks.

The embodiment of the application provides a signal transmission system, which comprises a main unit device, a far-end frequency conversion device and a coaxial network for connecting the main unit device and the far-end frequency conversion device in a communication manner;

the main unit device is used for respectively carrying out up-conversion processing on each digital baseband signal in the input multi-channel digital baseband signals to obtain multiple paths of intermediate frequency signals with different frequencies, and carrying out combining processing on the multiple paths of intermediate frequency signals to obtain a first combined intermediate frequency signal;

the coaxial network is used for transmitting the first combined intermediate frequency signal to the far-end frequency conversion equipment;

the far-end frequency conversion equipment is used for carrying out shunt processing on the received first combined intermediate frequency signal to obtain intermediate frequency signals with different frequencies, carrying out up-conversion processing on each path of intermediate frequency signal to obtain radio frequency signals with carrier frequency specified by an operator, and sending each path of obtained radio frequency signals through each antenna of the far-end frequency conversion equipment.

The signal transmission system can convert the multi-channel digital baseband signals into intermediate frequency signals with different frequencies in a frequency division multiplexing mode, transmit the intermediate frequency signals to the far-end frequency conversion equipment through the coaxial network, and convert the intermediate frequency signals into radio frequency signals with carrier frequencies specified by an operator through shunting of the far-end frequency conversion equipment to send out. Therefore, under the condition that the existing coaxial network is not required to be upgraded, the MIMO function can be supported only by one coaxial network.

Optionally, in an optional implementation manner of the present application, the far-end frequency conversion device is further configured to perform down-conversion processing on each path of radio frequency signals received by each antenna of the far-end frequency conversion device to obtain multiple paths of intermediate frequency signals with different frequencies, and perform combining processing on the multiple paths of intermediate frequency signals to obtain a second combined intermediate frequency signal;

the coaxial network is further configured to transmit the second combined intermediate frequency signal to the master unit device;

and the main unit device is further configured to perform shunt processing on the received second combined intermediate frequency signal to obtain multiple paths of intermediate frequency signals with different frequencies, and perform down-conversion processing on each path of intermediate frequency signal to obtain digital baseband signals of respective channels.

Optionally, in an optional implementation manner of the present application, the master unit device is further configured to control the remote frequency conversion device by sending a control signal, where the control signal includes a TDD switching control signal for controlling a switching state of the remote frequency conversion device, a clock synchronization signal for performing clock synchronization on different remote frequency conversion devices, and a management signal for configuring, adjusting, and managing the remote frequency conversion device.

Through the control signals, the main unit equipment can uniformly manage the remote frequency conversion equipment, and the whole system can be controlled.

Optionally, in an optional embodiment of the present application, the far-end frequency conversion device is further configured to perform gain adjustment on a signal received or transmitted through the coaxial network, so as to compensate for a path loss of the signal transmitted on the coaxial network.

By adjusting the gain of the signal, the problem of overlarge signal loss caused by feeder loss can be solved, and the signal can be sent out through the antenna.

Optionally, in an optional implementation manner of the present application, the number of the main unit devices and the number of the remote frequency conversion devices are plural, and the signal transmission system includes a first combiner/splitter connected between the main unit devices and the coaxial network, and a second combiner/splitter connected between the remote frequency conversion devices and the coaxial network;

the first combiner/splitter is configured to combine the intermediate frequency signals output by each main unit device to obtain a third combined intermediate frequency signal, where each main unit device correspondingly processes a digital baseband signal of an operator; or the fourth combined intermediate frequency signal received from the coaxial network is shunted to obtain an intermediate frequency signal of an operator corresponding to each main unit device, so that each main unit device performs down-conversion processing based on the intermediate frequency signal to obtain a digital baseband signal of the corresponding operator;

the second combiner/splitter is configured to split the third combined intermediate frequency signal received from the coaxial network to obtain intermediate frequency signals of different frequencies, or combine intermediate frequency signals from different remote frequency conversion devices to obtain a fourth combined intermediate frequency signal after combination.

In this embodiment, multiple signals from multiple operators can be multiplexed into the same coaxial network for transmission, and signals with higher frequencies (such as 5G signals) can be transmitted down to a low frequency band with better transmission characteristics. The multiplexed intermediate frequency signals are distributed to remote units and antennas of the operator at a plurality of locations.

Optionally, in an optional implementation manner of the present application, when the coaxial network is a cable television coaxial network, the signal transmission system further includes: an impedance matching network, a CATV/MU combiner and a CATV/FCU splitter;

the CATV/MU combiner is used for receiving the cable television signal and the first combined intermediate frequency signal output by the main unit equipment, and combining the cable television signal and the first combined intermediate frequency signal to obtain a fifth combined intermediate frequency signal; or the second combined intermediate frequency signal in the cable television coaxial network is provided to the main unit device after being subjected to shunt processing;

the CATV/FCU splitter is used for being connected with the cable television coaxial network and the far-end frequency conversion equipment respectively and for splitting the fifth combined intermediate-frequency signal to output a cable television signal and the first combined intermediate-frequency signal; or transmitting the second combined intermediate frequency signal generated by the far-end frequency conversion equipment through the cable television coaxial network;

the impedance matching network is arranged between the main unit device and the CATV/MU combiner and between the far-end frequency conversion device and the CATV/FCU branching unit, and is used for matching the interface impedance of the far-end frequency conversion device and the cable television coaxial network and matching the interface impedance of the main unit device and the cable television coaxial network.

In such an embodiment, a cable television coaxial network is used as the coaxial network, and wireless communication signals (such as 5G signals) can be permeated into the home of a residential user at a low cost.

An embodiment of the present application further provides a signal transmission method applied to a signal transmission system, where the signal transmission system includes a main unit device, a far-end frequency conversion device, and a coaxial network for communicatively connecting the main unit device and the far-end frequency conversion device, and the method includes:

the main unit device respectively carries out up-conversion processing on each digital baseband signal in the input multi-channel digital baseband signals to obtain intermediate frequency signals of different frequencies corresponding to each channel digital baseband signal, and combines each intermediate frequency signal to obtain a first combined intermediate frequency signal;

the main unit device transmits the first combined intermediate frequency signal to the far-end frequency conversion device through the coaxial network;

after receiving the first combined intermediate-frequency signal, the far-end frequency conversion equipment branches intermediate-frequency signals with different frequencies from the first combined intermediate-frequency signal;

the remote frequency conversion equipment performs up-conversion processing on the intermediate frequency signals with different frequencies to obtain radio frequency signals with carrier frequencies specified by an operator, and sends the obtained multiple radio frequency signals through each antenna of the remote frequency conversion equipment.

Optionally, in an optional embodiment of the present application, the method further comprises:

the far-end frequency conversion equipment carries out down-conversion processing on each path of radio frequency signals received by each antenna of the far-end frequency conversion equipment to obtain multiple paths of intermediate frequency signals with different frequencies, and combines the multiple paths of intermediate frequency signals to obtain a second combined intermediate frequency signal;

the far-end frequency conversion equipment sends the second combined intermediate frequency signal to the main unit equipment;

and the main unit device performs shunt processing on the received second combined intermediate frequency signal to obtain intermediate frequency signals with different frequencies, and performs down-conversion processing on each path of intermediate frequency signal to obtain digital baseband signals of respective channels.

Optionally, in an optional implementation manner of the present application, the number of the main unit devices and the number of the remote frequency conversion devices are plural, and the signal transmission system includes a first combiner/splitter connected between the main unit devices and the coaxial network, and a second combiner/splitter connected between the remote frequency conversion devices and the coaxial network; the method further comprises the following steps:

the first combiner/splitter combines the intermediate frequency signals output by each main unit device to obtain a third combined intermediate frequency signal, and each main unit device correspondingly processes a digital baseband signal of an operator; or the fourth combined intermediate frequency signal received from the coaxial network is shunted to obtain an intermediate frequency signal of an operator corresponding to each main unit device, so that each main unit device performs down-conversion processing based on the intermediate frequency signal of the operator to obtain a digital baseband signal of the operator;

and the second combiner/splitter splits the third combined intermediate frequency signal received from the coaxial network to obtain intermediate frequency signals of different frequencies of each operator, or combines intermediate frequency signals from different remote frequency conversion devices to obtain a combined fourth combined intermediate frequency signal.

Optionally, in an optional implementation manner of the present application, when the coaxial network is a cable television coaxial network, the signal transmission system further includes: the impedance matching network is arranged between the main unit equipment and the CATV/MU combiner, and between the far-end frequency conversion equipment and the CATV/FCU splitter and used for matching the impedance of the interface of the far-end frequency conversion equipment with the coaxial network of the cable television and matching the impedance of the interface of the main unit equipment with the coaxial network of the cable television; the method further comprises the following steps:

the CATV/MU combiner combines the received cable television signal and the first combined intermediate frequency signal output by the main unit device to obtain a fifth combined intermediate frequency signal; or the second combined intermediate frequency signal in the cable television coaxial network is provided to the main unit device after being subjected to shunt processing;

the CATV/FCU branching unit branches the fifth combined intermediate frequency signal to output a cable television signal and the first combined intermediate frequency signal; or transmitting the second combined intermediate frequency signal generated by the far-end frequency conversion equipment through the cable television coaxial network.

According to the signal transmission system and the signal transmission method provided by the embodiment of the application, the multi-channel digital baseband signal can be converted into intermediate frequency signals with different frequencies in a frequency division multiplexing mode, the intermediate frequency signals are transmitted to the far-end frequency conversion equipment through the coaxial network, and the intermediate frequency signals are converted into radio frequency signals with carrier frequencies specified by an operator through the shunt of the far-end frequency conversion equipment and are transmitted out. The process is reversed in the signal reception direction. Therefore, under the condition that the existing coaxial network is not required to be upgraded, the MIMO function can be supported only by one coaxial network.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a structural framework diagram of a signal transmission system according to an embodiment of the present application;

fig. 2 is a block diagram showing a detailed structure of the signal transmission system in fig. 1;

fig. 3 is a network topology diagram of a signal transmission system supporting MIMO function according to an embodiment of the present application;

fig. 4 is a signal transmission diagram of a signal transmission system supporting 4T4R according to an embodiment of the present application;

fig. 5 is a schematic structural diagram of a main unit device according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of a far-end frequency conversion device provided in an embodiment of the present application;

fig. 7 is a second schematic structural diagram of a main unit device according to an embodiment of the present application;

fig. 8 is a third schematic structural diagram of a main unit device according to an embodiment of the present application;

fig. 9 is a fourth schematic structural diagram of a main unit device according to an embodiment of the present application;

fig. 10 is a schematic diagram of a signal transmission system for transmitting multi-operator communication signals according to an embodiment of the present application;

FIG. 11 is a schematic diagram of a signal transmission system using a CATV coaxial network according to an embodiment of the present application;

fig. 12 is a flowchart of a signal transmission method according to an embodiment of the present application;

fig. 13 is a second flowchart of a signal transmission method according to an embodiment of the present application;

fig. 14 is a third flowchart of a signal transmission method according to an embodiment of the present application;

fig. 15 is a fourth flowchart of a signal transmission method according to an embodiment of the present application;

fig. 16 is a fifth flowchart of a signal transmission method according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the 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.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present application, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which the present invention product is usually put into use, it is only for convenience of describing the present application and simplifying the description, but it is not intended to indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and be operated, and thus, should not be construed as limiting the present application.

Furthermore, the appearances of the terms "first," "second," and the like, if any, are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

It should be noted that the features of the embodiments of the present application may be combined with each other without conflict.

The base station BS for contemporary mobile communication is generally composed of PDCP (packet data convergence layer), RLC (radio control layer), MAC (multimedia layer), PHY (physical layer), RF, duplex and antenna parts. In the present application, the original RF module will be split into two parts, i.e., Intermediate Frequency (IF) and up/down frequency conversion (UC/DC), and the base station (source part of the distributed antenna system) is divided into two parts, i.e., main unit device (MU) and remote frequency conversion device (FCU).

Referring to fig. 1, fig. 1 is a system architecture diagram of a signal transmission system according to an embodiment of the present application, where the signal transmission system includes a main unit device, a remote frequency conversion device, and a coaxial network for connecting the main unit device and the remote frequency conversion device.

In this embodiment of the present application, the main Unit device may be an integrated base station BS device that outputs an intermediate frequency signal and has complete functions, or may be a Remote Radio Unit (RRU) device that outputs an intermediate frequency signal. The main function of the far-end frequency conversion equipment is to convert the intermediate frequency into an up-down converter of a radio frequency carrier.

In the downstream, the digital baseband signal generated by the PHY module is first converted to a planned analog intermediate frequency f in the Main Unit (MU) by DAC (digital-to-analog conversion) and frequency conversion_IF-DLThe above step (1); the intermediate frequency signal is passed via a coaxial network to an up-conversion module (UC) of a remote frequency conversion device (FCU). The UC module transforms the downlink signal into carrier frequency specified by an operator and sends the carrier frequency out through an antenna.

In uplink, a communication signal received by an antenna from a mobile device is converted to a planned intermediate frequency f by a down-conversion module (DC) in the FCU_IF-UL(ii) a Then, the uplink communication signal is transmitted back to the main unit equipment MU along the original path through the coaxial network; in the main unit device MU, the intermediate frequency uplink signal is demodulated into a digital baseband signal through high-speed data sampling and frequency conversion processing, and is sent to an upper layer for processing.

However, in order to transmit the downstream and upstream signals in the same coaxial network, please refer to fig. 2, a duplexer is added at the if ports of the MU and the FCU. In the embodiment of the present application, the duplex system of wireless communication may be divided into frequency division duplex FDD and time division duplex TDD.

In a duplex mode of frequency division duplex, f_IF-DL≠f_IF-ULThe duplexer is of a filter bank type at the moment;

when the duplex mode is a time division duplex mode,f_IF-DL＝f_IF-ULthe duplexer is of a switch type at this time.

The above describes the processing procedure of a single-channel signal, and the main objective of the present application is to convert a plurality of communication channels of an mTmR base station into different intermediate frequencies by means of frequency conversion, so as to implement frequency multiplexing, i.e. FDM-IF, on the intermediate frequency, so that multiple channels of wireless communication signals can be transmitted in the same coaxial network and distributed to FCUs and antennas with mTmR function at multiple locations.

To implement a coaxial network supporting Multiple Input Multiple Output (MIMO) function, please refer to fig. 3, and fig. 3 shows a network topology diagram for implementing the coaxial network supporting MIMO function.

In a network topology, through a coaxial network, one MU can implement point-to-multipoint transmission with FCUs at multiple locations, and control and manage multiple FCUs. However, it should be noted that the set of FDM-IF channel resources are shared among FCUs at multiple locations, i.e., multiple antennas at different locations of the coaxial network end are equivalent to covering the same sector of the wireless base station.

If the communication system of the operator is TDD, in the same sector, even in the whole coverage area of the operator. The control of the switch is uniform, the switch control in the FCU can be realized by a plurality of methods, and the common methods are as follows: the MU transmits the real-time data to the FCUs, or the MU sends the control signals in the form of pulses directly to the FCUs. The former requires the MU to establish a real-time data communication channel with the FCU, and the latter requires simple modulation of control signals in the form of TTL onto a single carrier frequency that can be supported by the coax system.

Even the former real-time data channel needs to transmit and receive data via the coaxial system. The low-cost and universal modes such as FSK, BPSK, QPSK, QAM and the like can be adopted. The modulated carrier must also be selected to be the frequency that the coaxial system can support.

Besides the TDD switching control, a non-real-time management channel needs to be established between the MU and the FCU to configure, adjust and manage the remote FCU device.

In addition, the frequency of the local oscillator LO required by the up-down converter also needs to be synchronously locked between many FCU devices. This requires that the clock signal of the MU be sent to each FCU at the same time. To ensure that the clock signal transmission is less disturbed, the clock signal may be additionally modulated onto a separate carrier.

The carriers for the three functions described above (control of the TDD switch, transmission of clock synchronization signals, management of the FCU device) may be collectively referred to as control signals (out-of-band OOB signals). In the embodiment of the present application, the MU may control the FCU by transmitting the control signal.

In the embodiment of the present application, a specific technical solution of the present application is described below by taking 4x4 MIMO as an example, but it should be understood that the example is only an illustration for explaining the technical solution of the present application, and should not be construed as limiting the technical solution claimed in the present application.

Specifically, in the downlink, please refer to fig. 4 and 5, assuming that the master unit MU has 4 wireless communication channels (4T4R), ch1, ch2, ch3, and ch4, respectively. The 4 channels of downstream signals are modulated to a frequency f in the final module of the main unit device MU_IF1-DL，f_IF2-DL，f_IF3-DL，f_IF4-DLOf the intermediate frequency signal. At the output port of the MU, the four intermediate frequency signals are combined into a first combined intermediate frequency signal via a combining device. Since these four intermediate frequency signals are separated in frequency, they are referred to as frequency division multiplexed intermediate frequency signals FDM-IF. The main unit device MU transmits the first combined intermediate frequency signal to the remote frequency conversion device FCU having 4 channels (4T4R) through the coaxial network.

Referring to fig. 4 and fig. 6, after receiving the first combined intermediate frequency signal, the FCU first divides the first combined intermediate frequency signal into 4 paths of signals by the splitting device, and each path of signal is filtered by the frequency selection device to obtain the corresponding intermediate frequency signal f_IFi-DL(i is 1 to 4). The signals are up-converted once again, and all 4 signals are up-converted to the same carrier frequency f_RF-DLAnd then transmitted by 4 antennas respectively.

In uplink, when 4 antennas connected to a FCU of a 4T4R receive signals of a mobile device in its coverage area (carrier frequency f)_RF-UL) Are respectively reduced to a frequency f by a down converter inside the FCU unit_IF1-UL、f_IF2-UL、f_IF3-UL、f_IF4-ULAnd then combined into a second combined intermediate frequency signal of the FDM-IF into the coaxial network. When the set of FDM-IF signals reaches the MU of 4T4R, they are also split and frequency-selected into 4 separate upstream signals, demodulated, and processed by upper layers.

Thus, the 4T4R of the base station can respectively correspond to the 4 antennas at the far end, and the MIMO of 4x4 is realized. It should be noted, however, that all 4T4R FCU units at different locations on the end of the coaxial network are in a shared relationship with the 4T4R resources of the MU units.

In the above process, in the same reason as the single channel, when the duplex system of the operator is FDD,

f_RF-DL≠f_RF-UL

f_IF1-DL≠f_IF1-UL

f_IF2-DL≠f_IF2-UL

f_IF3-DL≠f_IF3-UL

f_IF4-DL≠f_IF4-UL

and the duplexer is of the filter bank type. When the operating system is a TDD system,

f_RF-DL＝f_RF-UL

f_IF1-DL＝f_IF1-UL

f_IF2-DL＝f_IF2-UL

f_IF3-DL＝f_IF3-UL

f_IF4-DL＝f_IF4-UL

and the duplexer is of a switch type.

In the embodiment of the present application, the MU may correspond to different structures according to different signal processing flows, and specifically, please refer to fig. 5 again, which is a possible implementation of the embodimentIn the prior art, the digital baseband signals of each downlink channel transmitted from a forward port are extracted, then are subjected to digital up-conversion DUC to a designed intermediate frequency point, and then are converted into an analog intermediate frequency, namely f_IF1-DL、...、f_IF4-DL. In the upstream direction, the intermediate frequency f is then simulated_IF1-UL、...、f_IF4-ULThe digital baseband signal is converted into a digital signal through ADC (analog-to-digital conversion), then is converted into a digital baseband signal through digital down-conversion DDC, and is sent to a forward port.

Optionally, in a possible implementation scheme of this embodiment, in order to solve the technical problem of excessive signal loss caused by feeder loss, referring to fig. 7, in this embodiment of the present application, a power amplifier may be added in a downlink channel of the MU structure in fig. 5, and a low noise amplifier may be added in an uplink channel, so as to perform gain enhancement on a signal.

Optionally, in a possible implementation of this embodiment, the order of frequency conversion and analog-to-digital conversion in the MU structure of fig. 5 or fig. 7 may also be adjusted. Specifically, after the downlink digital baseband signals of each channel transmitted from the forward port are extracted, the downlink digital baseband signals are firstly converted into analog baseband signals through the DAC, and then modulated to the designed frequency point, namely f, through the analog up-converter_IF1-DL,...,f_IF4-DL. And in the upstream direction, the intermediate frequency f to be simulated_IF1-UL,...,f_IF4-ULIt is first demodulated into an analog baseband signal by an "analog" down-conversion, and then converted into a digital baseband signal by an ADC, and sent to a "forward" port, as can be seen in fig. 8.

Optionally, in a possible implementation of this embodiment, when the operation mode of the duplexer in the MU is TDD, since the duplexers, that is, the TDD switches of the channels are completely synchronized, the TDD duplex switches of the four channels may be combined, and one TDD duplex switch is adopted for overall control, which may specifically refer to fig. 9.

It should be understood, of course, that the above description is merely illustrative of possible configurations of the MU, and that any variation of the MU configuration that achieves the above-described functionality of the MU is within the scope of the present application. Similarly, any variation of the FCU structure that achieves the above-described functions of the FCU is within the scope of the present application and is not limited to the structure shown in fig. 6.

In another application scenario provided in the embodiment of the present application, the number of main unit devices and the number of remote frequency conversion devices in the signal transmission system are multiple, where each main unit device correspondingly processes a digital baseband signal of an operator. Referring to fig. 10, the signal transmission system may further include a first combiner/splitter connected between the main unit device and the coaxial network, and a second combiner/splitter connected between the remote frequency conversion device and the coaxial network.

In the downstream direction, it is assumed that there are communication signals of three operators, which need to be transmitted in the form of intermediate frequencies in the coaxial network, the signals of which are S respectively_IFa，S_IFb，S_IFc. These intermediate frequency signals may be single-channel signals, or may be the aforementioned MIMO-capable multi-channel first combined intermediate frequency signals. The main unit equipment and the far-end frequency conversion equipment corresponding to the three operators are respectively MU_a，MU_b，MU_cAnd FCU_a，FCU_b，FCU_c。

MU_a，MU_b，MU_cOutput intermediate frequency signal S_IFa，S_IFb，S_IFcAnd obtaining a third combined intermediate frequency signal through the combination processing of the first combiner/divider, and merging the third combined intermediate frequency signal into a coaxial network. And when the remote end is reached, the third combined intermediate frequency signal is divided into radio frequency signals with the frequency specified by the operator through the second combiner/divider, and the radio frequency signals are sent to the respective FCUs and are sent out through the antenna after being processed by the FCUs.

In the upstream direction, the second combiner/splitter will originate from the FCU_a、FCU_bAnd FCU_cThe intermediate frequency signals are combined to obtain a fourth combined intermediate frequency signal, and the fourth combined intermediate frequency signal is converged into a coaxial network. At the far end, the fourth combined intermediate-frequency signal is split into operation by the first combiner/splitterThe single-channel or multi-channel intermediate frequency signals with the specified frequency are sent to the respective MU to be processed.

In another application scenario provided in the embodiment of the present application, referring to fig. 11, the coaxial network is a cable television coaxial network, and the signal transmission system may further include: the system comprises an impedance matching network, a CATV/MU combiner and a CATV/FCU splitter, wherein the CATV/MU combiner is arranged between a main unit device MU and a cable television coaxial network, and the CATV/FCU splitter is arranged between a far-end frequency conversion device and the cable television coaxial network;

in this application scenario, the transmission impedance of the cable television coaxial network is 75 ohms, unlike the 50 ohm impedance used by conventional DAS room coax networks. The interfaces (intermediate frequency interfaces) of the MU equipment and the FCU equipment with the cable television coaxial network should be matched with the MU equipment and the FCU equipment. In this scenario, impedance matching networks are provided between the main unit device and the CATV/MU combiner, and between the remote frequency conversion device and the CATV/FCU splitter, for impedance matching of the interface of the remote frequency conversion device and the cable television coaxial network, and impedance matching of the interface of the main unit device and the cable television coaxial network. The matched MU and FCU devices can borrow frequency bands not occupied by the cable television to transmit wireless communication signals in a coaxial network of the cable television.

It is contemplated that cable television's own CATV signals will also need to continue to be transmitted in the coaxial system. In order not to affect each other, in the downlink direction, the CATV/MU combiner is configured to combine the first combined intermediate frequency signal of the MU with the CATV signal to obtain a fifth combined intermediate frequency signal. At the remote end, the CATV/FCU splitter splits the fifth combined intermediate frequency signal into a cable television signal and a first combined intermediate frequency signal. In the upstream direction, at the near end, the second combined intermediate frequency signal is converged into the coaxial network through the CATV/FCU branching unit; at the remote end, the CATV/MU combiner separates the signal from the second combined intermediate frequency signal for processing by the master unit device.

Referring to fig. 12, in a downlink direction, the signal transmission method specifically includes the following steps:

step S110, the main unit device respectively performs up-conversion processing on each digital baseband signal in the input multi-channel digital baseband signal to obtain intermediate frequency signals of different frequencies corresponding to each channel digital baseband signal, and combines each intermediate frequency signal to obtain a first combined intermediate frequency signal;

step S120, the main unit device transmits the first combined intermediate frequency signal to the far-end frequency conversion device through the coaxial network;

step S130, after receiving the first combined intermediate frequency signal, the far-end frequency conversion equipment branches intermediate frequency signals with different frequencies from the first combined intermediate frequency signal;

step S140, the remote frequency conversion device performs up-conversion on the intermediate frequency signals with different frequencies to obtain radio frequency signals with carrier frequencies specified by the operator, and sends the obtained multiple radio frequency signals through each antenna of the remote frequency conversion device.

Referring to fig. 13, in the uplink direction, the signal transmission method may further include the following steps:

step S150, the far-end frequency conversion equipment carries out down-conversion processing on each path of radio frequency signal received by each antenna of the far-end frequency conversion equipment to obtain multiple paths of intermediate frequency signals with different frequencies, and combines the multiple paths of intermediate frequency signals to obtain a second combined intermediate frequency signal;

step S160, the far-end frequency conversion device sends the second combined intermediate frequency signal to the main unit device;

step S170, the main unit device performs a splitting process on the received second combined intermediate frequency signal to obtain intermediate frequency signals with different frequencies, and performs a down-conversion process on each path of intermediate frequency signal to obtain digital baseband signals of respective channels.

In a scenario provided by the present application, the number of the main unit devices and the number of the remote frequency conversion devices are multiple, and each main unit device correspondingly processes a digital baseband signal of an operator. Referring to fig. 14, in the downlink direction, the signal transmission method may include the following steps:

step S210, each master unit device modulates the digital baseband signals of its corresponding operator to obtain intermediate frequency signals with different frequencies, where the digital baseband signals of each operator may be single-channel signals or multi-channel signals;

step S220, the first combiner/splitter combines the intermediate frequency signals output by each main unit device to obtain a third combined intermediate frequency signal, and sends the third combined intermediate frequency signal to the second combiner/splitter through the coaxial network;

step S230, the second combiner/splitter splits the third combined intermediate frequency signal received from the coaxial network to obtain intermediate frequency signals of different frequencies of each operator, and distributes the intermediate frequency signals of different frequencies to corresponding remote frequency conversion devices;

in step S240, each remote frequency conversion device performs up-conversion on the received intermediate frequency signal to obtain a radio frequency signal with a carrier frequency specified by an operator, and sends the obtained radio frequency signal through each antenna of the remote frequency conversion device.

Referring to fig. 15, in the uplink direction, the signal transmission method may further include the following steps:

step S250, the remote frequency conversion equipment of each operator performs down-conversion processing on each path of radio frequency signal received by each antenna of the remote frequency conversion equipment to obtain multiple paths of intermediate frequency signals with different frequencies;

step S260, the second combiner/splitter combines the intermediate frequency signals from the far-end frequency conversion devices of different operators to obtain a fourth combined intermediate frequency signal after combination, and transmits the fourth combined intermediate frequency signal to the first combiner/splitter through the coaxial network;

step S270, the first combiner/splitter splits the fourth combined intermediate frequency signal received from the coaxial network to obtain the intermediate frequency signal of each main unit device corresponding to the operator;

in step S280, each master unit device performs down-conversion processing based on the intermediate frequency signal of the operator to obtain the digital baseband signal of the operator.

In a scenario provided by the present application, in the scenario, the coaxial network is a cable television coaxial network, and the signal transmission system may further include: the impedance matching network is arranged between the main unit equipment and the CATV/MU combiner, and between the far-end frequency conversion equipment and the CATV/MU splitter, and is used for matching the interface of the far-end frequency conversion equipment with the impedance of the cable television coaxial network, and matching the interface of the main unit equipment with the impedance of the cable television coaxial network.

Referring to fig. 16, in the downlink direction, the signal transmission method may include the following steps:

step S310, the CATV/MU combiner combines the received cable television signal and the first combined intermediate frequency signal output by the main unit device to obtain a fifth combined intermediate frequency signal;

step S320, the coaxial network transmits the fifth combined intermediate frequency signal to a CATV/FCU branching unit;

step S330, the CATV/FCU branching unit branches the fifth combined intermediate frequency signal to output the cable television signal and the first combined intermediate frequency signal.

In the upstream direction, the second combined intermediate frequency signal generated by the remote device enters the cable television coaxial network through the CATV/FCU splitter, and is separated out through the CATV/MU combiner and provided to the main unit device.

According to the signal transmission system and the signal transmission method provided by the embodiment of the application, the multi-channel digital baseband signal can be converted into intermediate frequency signals with different frequencies in a frequency division multiplexing mode, the intermediate frequency signals are transmitted to the far-end frequency conversion equipment through the coaxial network, and the intermediate frequency signals are converted into radio frequency signals with carrier frequencies specified by an operator through the shunt of the far-end frequency conversion equipment and are transmitted out. Therefore, under the condition that the existing coaxial network is not required to be upgraded, the MIMO function can be supported only by one coaxial network. Meanwhile, the system can also support the coaxial network transmission of multiple operator signals, or realize the scheme through an indoor deployed cable television coaxial network. The overall signal transmission system is less costly to deploy than existing digital room division schemes.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A signal transmission system comprising a main unit device, a remote frequency conversion device, and a coaxial network for communicatively connecting the main unit device and the remote frequency conversion device;

2. The signal transmission system of claim 1, wherein:

the far-end frequency conversion equipment is also used for carrying out down-conversion processing on each path of radio frequency signal received by each antenna of the far-end frequency conversion equipment to obtain a plurality of paths of intermediate frequency signals with different frequencies, and combining the plurality of paths of intermediate frequency signals to obtain a second combined intermediate frequency signal;

3. The signal transmission system according to claim 1 or 2, wherein:

the main unit device is further configured to control the remote frequency conversion device by sending a control signal, where the control signal includes a TDD switching control signal for controlling a switching state of the remote frequency conversion device, a clock synchronization signal for performing clock synchronization on different remote frequency conversion devices, and a management signal for configuring, adjusting, and managing the remote frequency conversion device.

4. The signal transmission system according to claim 1 or 2, wherein:

the far-end frequency conversion equipment is further used for carrying out gain adjustment on the signals received or sent through the coaxial network so as to compensate the path loss of the signals transmitted on the coaxial network.

5. The signal transmission system according to claim 1 or 2, wherein: the number of the main unit devices and the number of the far-end frequency conversion devices are multiple, and the signal transmission system comprises a first combiner/splitter connected between the main unit devices and the coaxial network and a second combiner/splitter connected between the far-end frequency conversion devices and the coaxial network;

6. The signal transmission system according to claim 1 or 2, wherein: when the coaxial network is a cable television coaxial network, the signal transmission system further includes: an impedance matching network, a CATV/MU combiner and a CATV/FCU splitter;

7. A signal transmission method applied to a signal transmission system including a main unit device, a remote frequency conversion device, and a coaxial network for communicatively connecting the main unit device and the remote frequency conversion device, the method comprising:

8. The method of signaling of claim 7, the method further comprising:

9. The signal transmission method according to claim 7 or 8, wherein the number of the master unit device and the number of the remote frequency conversion devices are plural, the signal transmission system includes a first combiner/splitter connected between the master unit device and the coaxial network, and a second combiner/splitter connected between the remote frequency conversion devices and the coaxial network; the method further comprises the following steps:

10. The signal transmission method of claim 7 or 8, wherein when the coaxial network is a cable television coaxial network, the signal transmission system further comprises: the impedance matching network is arranged between the main unit equipment and the CATV/MU combiner, and between the far-end frequency conversion equipment and the CATV/MU splitter and is used for matching the impedance of the interface of the far-end frequency conversion equipment with the coaxial network of the cable television and matching the impedance of the interface of the main unit equipment with the coaxial network of the cable television; the method further comprises the following steps: