5G communication system, device and method applied to special frequency band

Abstract

The embodiment of the invention provides a 5G communication system, device and method applied to a special frequency band. Through a 5G communication system applied to a special frequency band, when a near-end frequency conversion module transmits in a downlink direction, a to-be-sent intermediate frequency radio frequency signal is converted into an F1 frequency point to be transmitted; and during uplink transmission, converting the received signal of the F1 frequency point into an intermediate frequency radio frequency signal; the far-end frequency conversion module performs frequency conversion on the received signal of the frequency point F1 to the frequency point F2 when transmitting in the downlink direction; the method comprises the following steps of: during uplink transmission, converting a signal of an F2 frequency point to be transmitted at a far end to an F1 frequency point; wherein the F1 frequency point is a frequency point of a special frequency band used by a private network, and the F2 frequency point is a commercial frequency point of a public network of an operator. Through the given communication scheme, the allowed special frequency point can be used for transmitting the spatial radio frequency signal, and the radio frequency environment requirement of the system is met; and a signal suitable for a common terminal CPE is used after the remote end receives the signal and frequency conversion is carried out, so that the design requirement of a low-cost system is met.

Description

Technical Field

[0001] The present embodiment relates to the field of communication technology, and specifically, to a 5G communication system, device, and method for use in a special frequency band. Background Art

[0002] In 5G private network communication, some scenarios require special frequency band communication, such as airports, drones, AR video surveillance and other scenarios. Usually, only the permitted frequency points can be used for space RF transmission, such as the 5.1GHz frequency band for near- and far-end RF transmission communication. However, most terminals on the market do not support this special frequency band communication terminal, or the price is relatively high. Therefore, frequency conversion technology is needed to assist in completing the communication work suitable for ordinary terminals. Summary of the invention

[0003] In view of this, the purpose of the embodiments of the present invention is to provide a method for transmitting spatial RF signals using permitted special frequencies to meet the system RF environment requirements; and to use signals suitable for ordinary terminal CPE after receiving the signals at the remote end and converting the frequencies to meet the low-cost system design requirements.

[0004] A first aspect of the present invention provides a 5G communication system for a special frequency band, the system comprising a proximal unit and a remote unit, the proximal unit comprising a proximal frequency conversion module; the remote unit comprising a remote frequency conversion module; wherein: The near-end frequency conversion module is used to convert the intermediate frequency radio frequency signal to be sent into the F1 frequency point for transmission in the downlink direction; and to convert the received F1 frequency point signal into the intermediate frequency radio frequency signal in the uplink direction; The remote frequency conversion module is used to convert the received F1 frequency signal to the F2 frequency when transmitting in the downlink direction; and to convert the F2 frequency signal to be transmitted at the remote end to the F1 frequency when transmitting in the uplink direction; wherein the F1 frequency is a frequency of a special frequency band approved for use in the private network, and the F2 frequency is a frequency used commercially in the operator's public network.

[0005] Furthermore, the proximal unit further includes a baseband processing unit BBU and a remote radio unit RRU; the remote unit further includes a customer premises equipment CPE; the proximal unit and the remote unit both include an antenna unit; The baseband processing unit BBU is used for baseband protocol processing and provides a backhaul interface with the core network and an interconnection interface between base stations; The remote radio unit RRU is used to convert the baseband signal into an intermediate frequency radio frequency signal, and to perform transceiver processing of the radio frequency signal; The customer premises equipment CPE is used to convert the received F2 frequency signal into a local wired or wireless signal.

[0006] Preferably, the remote unit also includes a synchronization signal extraction module; the synchronization signal extraction module is used to extract the synchronization signal and send it to the remote frequency conversion module; wherein: the synchronization signal extraction module receives the broadcast signal of the 5G macro station, parses the macro station downlink synchronization broadcast block SSB information, and thus obtains the synchronization signal.

[0007] Preferably, the remote radio unit RRU is further used for: When transmitting in the downlink direction, it receives the in-phase and quadrature IQ signals from the baseband processing unit BBU, and converts them to F1 frequency signals after up-conversion, digital-to-analog conversion, and RF modulation. During uplink transmission, the remote radio unit RRU receives the uplink F1 frequency RF signal through the antenna unit, and after low noise amplification, filtering, demodulation and receiving link processing, it performs analog-to-digital conversion and down-conversion, converts it into an in-phase orthogonal IQ signal and sends it to the baseband processing unit BBU.

[0008] Preferably, the remote frequency conversion module is further used for: Frame synchronization and time division duplex (TDD) switch switching enable are completed according to the received synchronization signal.

[0009] In addition, a second aspect of the present invention provides a proximal device for 5G communication in a special frequency band, comprising a baseband processing unit BBU, a remote radio unit RRU, and a proximal frequency conversion module; The baseband processing unit BBU is used for baseband protocol processing and provides a backhaul interface with the core network and an interconnection interface between base stations; The remote radio unit RRU is used to convert the baseband signal into an intermediate frequency radio frequency signal, and to perform transceiver processing of the radio frequency signal; The near-end frequency conversion module is used to convert the intermediate frequency RF signal to be sent into the F1 frequency point for transmission during downlink transmission; and to convert the received F1 frequency point signal into an intermediate frequency RF signal during uplink transmission; wherein the F1 frequency point is a frequency point of a special frequency band approved for use by the private network.

[0010] In addition, a third aspect of the present invention provides a remote device for 5G communication in a special frequency band, comprising a remote frequency conversion module, a synchronization signal extraction module, and a customer premises equipment CPE; wherein: The remote frequency conversion module is used to perform frequency conversion on the received F1 frequency point signal to the F2 frequency point when transmitting in the downlink direction; and to perform frequency conversion on the F2 frequency point signal to be transmitted at the remote end to the F1 frequency point when transmitting in the uplink direction; A synchronization signal extraction module is used to convert baseband signals into intermediate frequency radio frequency signals, and to perform transceiver processing of radio frequency signals; The customer premises equipment CPE is used to convert the received F2 frequency signal into a local wired or wireless signal; the F2 frequency is the frequency used by the operator's public network for commercial use.

[0011] In addition, a fourth aspect of the present invention provides a 5G communication method for a special frequency band according to the first aspect, the method comprising: S201, the remote radio unit RRU receives the in-phase and quadrature IQ signals transmitted from the baseband processing unit BBU, and converts them to F1 frequency signals through up-conversion, digital-to-analog conversion and radio frequency modulation; S202, the near-end frequency conversion module converts the intermediate frequency radio frequency signal modulated to the F1 frequency point to be transmitted to the F1 frequency point for transmission; and transmits the F1 frequency point signal through the antenna unit of the near-end unit; S203, the remote frequency conversion module receives the F1 frequency signal sent by the local frequency conversion module, performs frequency conversion to the F2 frequency signal; and sends the F2 frequency signal after frequency conversion to the customer premises equipment CPE; S204, the customer premises equipment CPE receives the F2 frequency point signal after frequency conversion sent by the remote frequency conversion module, and converts it into a local network signal, which is used by the local device to access the local network signal.

[0012] In the scheme of this embodiment, a 5G communication system for special frequency bands is designed to meet the needs of customer terminals for communication in special frequency bands. The system includes a proximal unit and a distal unit, the proximal unit including a proximal frequency conversion module; the distal unit including a distal frequency conversion module; wherein the proximal frequency conversion module is used to convert the intermediate frequency RF signal to be sent into the F1 frequency point for transmission when transmitting in the downlink direction; and to convert the received F1 frequency point signal into the intermediate frequency RF signal when transmitting in the uplink direction; the distal frequency conversion module is used to convert the received F1 frequency point signal into the F2 frequency point when transmitting in the downlink direction; and to convert the F2 frequency point signal to be transmitted at the far end into the F1 frequency point when transmitting in the uplink direction; wherein the F1 frequency point is the frequency point of the special frequency band approved for use by the private network, and the F2 frequency point is the frequency point used for commercial use in the operator's public network. Based on this, through the given communication scheme, it is possible to use the allowed special frequency points to transmit spatial RF signals to meet the system RF environment requirements; and after receiving the signal at the remote end and converting the frequency, use the signal suitable for ordinary terminal CPE to meet the low-cost system design requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present embodiment and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 It is a schematic diagram of the structure of a 5G communication system used in a special frequency band disclosed in an embodiment of the present invention; Figure 2 It is a flow chart of a 5G communication method for a special frequency band disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0016] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, systems, steps, etc. can be adopted. In other cases, known methods, systems, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0017] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor systems and / or microcontroller systems.

[0018] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0019] It should be noted that the “plurality” mentioned in this article refers to two or more.

[0020] The implementation details of the technical solution of the embodiment of the present application are described in detail below: See also Figure 1 , Figure 1 Schematic diagram of a 5G communication system structure used in a special frequency band disclosed in this embodiment. Figure 1 As shown, the system includes a proximal unit and a distal unit, the proximal unit includes a proximal frequency conversion module; the distal unit includes a distal frequency conversion module; wherein: The near-end frequency conversion module is used to convert the intermediate frequency radio frequency signal to be sent into the F1 frequency point for transmission in the downlink direction; and to convert the received F1 frequency point signal into the intermediate frequency radio frequency signal in the uplink direction; The remote frequency conversion module is used to convert the received F1 frequency signal to the F2 frequency when transmitting in the downlink direction; and to convert the F2 frequency signal to be transmitted at the remote end to the F1 frequency when transmitting in the uplink direction; wherein the F1 frequency is a frequency of a special frequency band approved for use in the private network, and the F2 frequency is a frequency used commercially in the operator's public network.

[0021] Furthermore, the proximal unit also includes a baseband processing unit BBU and a remote radio unit RRU; the remote unit also includes a customer premises equipment CPE; and the proximal unit and the remote unit both include an antenna unit.

[0022] Specifically, in this embodiment, the 5G communication system provided by the present invention for use in a special frequency band is mainly divided into two parts, namely, a proximal unit and a remote unit. The proximal unit includes a BBU (Building Baseband Unit) and an RRU (Remote Radio Unit). The remote unit includes a frequency conversion module and a CPE (Customer Premise Equipment, i.e., wireless terminal access equipment).

[0023] The baseband processing unit BBU is used for baseband protocol processing and provides a backhaul interface with the core network and an interconnection interface between base stations; Specifically, in this embodiment, BBU: The baseband processing unit BBU is responsible for baseband protocol processing, including the entire user plane (User Plane, UP) and control plane (Control Plane, CP) protocol processing functions, and provides a backhaul interface between the core network and an interconnection interface between base stations.

[0024] A synchronization signal extraction module is used to convert baseband signals into intermediate frequency radio frequency signals, and to perform transceiver processing of radio frequency signals; Preferably, the remote radio unit RRU is further used for: When transmitting in the downlink direction, it receives the in-phase and quadrature IQ signals from the baseband processing unit BBU, and converts them to F1 frequency signals after up-conversion, digital-to-analog conversion, and RF modulation. During uplink transmission, the remote radio unit RRU receives the uplink F1 frequency RF signal through the antenna unit, and after low noise amplification, filtering, demodulation and receiving link processing, it performs analog-to-digital conversion and down-conversion, converts it into an in-phase orthogonal IQ signal and sends it to the baseband processing unit BBU.

[0025] Specifically, in this embodiment, RRU: remote radio unit; RRU mainly completes the conversion between baseband signals and radio frequency signals and the transceiver processing functions of radio frequency signals. In the downlink direction, the IQ signal from the baseband processing unit BBU is received, and after up-conversion, digital-to-analog conversion, radio frequency modulation to F1 frequency signal, filtering, signal amplification and other transmission link processing, it is transmitted through the switch and antenna unit. In the uplink direction, the remote radio frequency unit RRU receives the uplink F1 frequency radio frequency signal through the antenna unit, and after low noise amplification, filtering, demodulation and other reception link processing, it is converted into an analog-to-digital conversion, down-converted, converted into an IQ signal and sent to the baseband processing unit BBU.

[0026] Specifically, in this embodiment, the near-end frequency conversion module mainly converts the intermediate frequency radio frequency signal to the F1 frequency point for transmission in the downlink, and converts the F1 frequency point into the intermediate frequency radio frequency signal in the uplink.

[0027] Further, regarding remote units, see Figure 1 , including: remote frequency conversion module; synchronization signal extraction module; and customer premises equipment CPE.

[0028] Furthermore, the remote frequency conversion module is used to convert the received signal of the F1 frequency point to the F2 frequency point when transmitting in the downlink direction; and to convert the signal of the F2 frequency point to be transmitted at the remote end to the F1 frequency point when transmitting in the uplink direction; wherein the F1 frequency point is a frequency point of a special frequency band approved for use in the private network, and the F2 frequency point is a frequency point for commercial use in the operator's public network.

[0029] Preferably, the remote unit also includes a synchronization signal extraction module; the synchronization signal extraction module is used to extract the synchronization signal and send it to the remote frequency conversion module; wherein: the synchronization signal extraction module receives the broadcast signal of the 5G macro station, parses the macro station downlink synchronization broadcast block SSB information, and thus obtains the synchronization signal.

[0030] Further, preferably, the remote frequency conversion module is also used to: complete frame synchronization and time division duplex TDD switch switching enable according to the received synchronization signal.

[0031] Specifically, in this embodiment, the remote frequency conversion module mainly completes the conversion of the downlink F1 frequency point to the F2 frequency point, and then converts the uplink F2 frequency point to the F1 frequency point. At the same time, according to the synchronization signal provided by the synchronization signal extraction module, frame synchronization and TDD (Time Division Duplexing) switch switching are completed.

[0032] Synchronization signal extraction module: completes the extraction of synchronization signals for use by the frequency conversion module. The synchronization signal extraction module receives the broadcast signal of the 5G macro station, parses the downlink SSB information of the macro station, and extracts the 10ms frame header signal. SSB (SynchronizationSignal / PBCH, synchronization broadcast block) is one of the most important pilot channels used in 5G. The SSB signal content includes PSS, DMRS, SSS, PBCH and other signals. In more detail, the SSB signal includes the system frame number, half-frame information, time domain characteristics, etc. The synchronization signal extraction module extracts the 10ms frame header according to the characteristics of SSB and outputs it to the remote frequency conversion module for RF switch switching.

[0033] In 5G, SSB includes synchronization signals and broadcast signals. The specific synchronization signals include PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal); the broadcast signals include PBCH Data and PBCH DMRS signals. Specifically, SSB occupies 4 OFDM symbols in the time domain and 20 RBs in the frequency domain.

[0034] Furthermore, the customer premises equipment CPE is used to convert the received F2 frequency signal into a local wired or wireless signal.

[0035] Specifically, in this embodiment, the customer premises equipment (CPE), i.e., the CPE module, converts 5G signals into WiFi or wired signals, enabling more local devices (mobile phones, tablets, computers) to access the Internet. This is very practical in scenarios such as airports, drones, and AR video surveillance.

[0036] In addition, a second aspect of this embodiment provides a proximal device for 5G communication in a special frequency band, including a baseband processing unit BBU, a remote radio unit RRU, and a proximal frequency conversion module; Figure 1 The module consists of the proximal unit.

[0037] The baseband processing unit BBU is used for baseband protocol processing and provides a backhaul interface with the core network and an interconnection interface between base stations; The remote radio unit RRU is used to convert the baseband signal into an intermediate frequency radio frequency signal, and to perform transceiver processing of the radio frequency signal; The near-end frequency conversion module is used to convert the intermediate frequency RF signal to be sent into the F1 frequency point for transmission during downlink transmission; and to convert the received F1 frequency point signal into an intermediate frequency RF signal during uplink transmission; wherein the F1 frequency point is a frequency point of a special frequency band approved for use by the private network.

[0038] In addition, a third aspect of this embodiment provides a remote device for 5G communication in a special frequency band, including a remote frequency conversion module, a synchronization signal extraction module, and a customer premises equipment CPE; Figure 1 The remote unit consists of modules.

[0039] The remote frequency conversion module is used to perform frequency conversion on the received F1 frequency point signal to the F2 frequency point when transmitting in the downlink direction; and to perform frequency conversion on the F2 frequency point signal to be transmitted at the remote end to the F1 frequency point when transmitting in the uplink direction; The remote radio unit RRU is used to convert the baseband signal into an intermediate frequency radio frequency signal, and to perform transceiver processing of the radio frequency signal; The customer premises equipment CPE is used to convert the received F2 frequency signal into a local wired or wireless signal; the F2 frequency is the frequency used by the operator's public network for commercial use.

[0040] In addition, a fourth aspect of this embodiment provides a 5G communication method for a special frequency band as described in the first aspect, such as Figure 2 The flowchart of the 5G communication method used in a special frequency band of this embodiment is shown. The method includes: S201, the remote radio unit RRU receives the in-phase orthogonal IQ signal transmitted from the baseband processing unit BBU, and converts it to F1 frequency point signal through up-conversion, digital-to-analog conversion and radio frequency modulation; S202, the near-end frequency conversion module converts the intermediate frequency radio frequency signal modulated to the F1 frequency point to be transmitted to the F1 frequency point for transmission; and transmits the F1 frequency point signal through the antenna unit of the near-end unit; S203, the remote frequency conversion module receives the F1 frequency signal sent by the local frequency conversion module, performs frequency conversion to the F2 frequency signal; and sends the F2 frequency signal after frequency conversion to the customer premises equipment CPE; S204, the customer premises equipment CPE receives the F2 frequency point signal after frequency conversion sent by the remote frequency conversion module, and converts it into a local network signal, which is used by the local device to access the local network signal.

[0041] The F1 frequency point is a frequency point of a special frequency band approved for use by a private network, and the F2 frequency point is a frequency point of a commercially available public network of an operator. For other details, please refer to the technical content of the first aspect.

[0042] Based on this, in the scheme of this embodiment, a 5G communication system for special frequency bands is designed to meet the needs of customer terminals for special frequency band communications. The system includes a proximal unit and a distal unit, the proximal unit including a proximal frequency conversion module; the distal unit including a distal frequency conversion module; wherein the proximal frequency conversion module is used to convert the intermediate frequency RF signal to be sent to the F1 frequency point for transmission when transmitting in the downlink direction; and to convert the received F1 frequency point signal to the intermediate frequency RF signal when transmitting in the uplink direction; the distal frequency conversion module is used to convert the received F1 frequency point signal to the F2 frequency point when transmitting in the downlink direction; and to convert the F2 frequency point signal to be transmitted at the far end to the F1 frequency point when transmitting in the uplink direction; wherein the F1 frequency point is the frequency point of the special frequency band approved for use by the private network, and the F2 frequency point is the frequency point used for commercial use in the operator's public network. Based on this, through the given communication scheme, it is possible to use the allowed special frequency points to transmit spatial RF signals to meet the system RF environment requirements; and after receiving the signal at the remote end and converting the frequency, use the signal suitable for ordinary terminal CPE to meet the low-cost system design requirements.

[0043] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this embodiment.

[0044] In the several embodiments provided in the present application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, systems or units, or it can be an electrical, mechanical or other form of connection.

[0045] The units described as separate components may or may not be physically separated. As a unit, it is apparent that those skilled in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this embodiment.

[0046] In addition, each functional unit in each embodiment of the present embodiment may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0047] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this embodiment is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a grid device, etc.) to perform all or part of the steps of the method described in each embodiment of this embodiment. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0048] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of this embodiment. It should be understood that the above description is only the specific implementation method of this embodiment and is not used to limit the protection scope of this embodiment. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this embodiment should be included in the protection scope of this embodiment.

Claims

1. A 5G communication system for a special frequency band, the system comprising a near-end unit and a remote unit, characterized in that: The proximal unit includes a proximal frequency conversion module; the remote unit includes a remote frequency conversion module; wherein: The near-end frequency conversion module is used to convert the intermediate frequency radio frequency signal to be sent into the F1 frequency point for transmission in the downlink direction; and to convert the received F1 frequency point signal into the intermediate frequency radio frequency signal in the uplink direction; The remote frequency conversion module is used to convert the received F1 frequency signal to the F2 frequency when transmitting in the downlink direction; and to convert the F2 frequency signal to be transmitted at the remote end to the F1 frequency when transmitting in the uplink direction; wherein the F1 frequency is a frequency of a special frequency band approved for use in the private network, and the F2 frequency is a frequency used commercially in the operator's public network.

2. The 5G communication system for special frequency bands according to claim 1, characterized in that: The proximal unit further includes a baseband processing unit BBU and a remote radio unit RRU; the remote unit further includes a customer premises equipment CPE; the proximal unit and the remote unit both include an antenna unit; The baseband processing unit BBU is used for baseband protocol processing and provides a backhaul interface with the core network and an interconnection interface between base stations; The remote radio unit RRU is used to convert the baseband signal into an intermediate frequency radio frequency signal, and to perform transceiver processing of the radio frequency signal; The customer premises equipment CPE is used to convert the received F2 frequency signal into a local wired or wireless signal.

3. The 5G communication system for special frequency bands according to claim 2, characterized in that: The remote unit further comprises a synchronization signal extraction module; the synchronization signal extraction module is used to extract the synchronization signal and send it to the remote frequency conversion module; wherein: The synchronization signal extraction module receives the broadcast signal of the 5G macro station, parses the macro station downlink synchronization broadcast block SSB information, and thus obtains the synchronization signal.

4. The 5G communication system for special frequency bands according to claim 3, characterized in that: The remote radio unit RRU is further used for: When transmitting in the downlink direction, it receives the in-phase and quadrature IQ signals from the baseband processing unit BBU, and converts them to F1 frequency signals after up-conversion, digital-to-analog conversion, and RF modulation. During uplink transmission, the remote radio unit RRU receives the uplink F1 frequency RF signal through the antenna unit, and after low noise amplification, filtering, demodulation and receiving link processing, it performs analog-to-digital conversion and down-conversion, converts it into an in-phase orthogonal IQ signal and sends it to the baseband processing unit BBU.

5. The 5G communication system for special frequency bands according to claim 4, characterized in that: The remote frequency conversion module is also used for: Frame synchronization and time division duplex (TDD) switch switching enable are completed according to the received synchronization signal.

6. A proximal device for 5G communication in a special frequency band, characterized in that: It includes baseband processing unit BBU, remote radio unit RRU, and near-end frequency conversion module; The baseband processing unit BBU is used for baseband protocol processing and provides a backhaul interface with the core network and an interconnection interface between base stations; The remote radio unit RRU is used to convert the baseband signal into an intermediate frequency radio frequency signal, and to perform transceiver processing of the radio frequency signal; The near-end frequency conversion module is used to convert the intermediate frequency radio frequency signal to be sent to the F1 frequency point for transmission when transmitting in the downlink direction; And when transmitting in the uplink direction, the received F1 frequency signal is converted into an intermediate frequency radio frequency signal; wherein the F1 frequency is a frequency of a special frequency band approved for use by the private network.

7. A remote device for 5G communication in a special frequency band, characterized in that: It includes a remote frequency conversion module, a synchronization signal extraction module, and a customer premises equipment CPE; wherein: The remote frequency conversion module is used to perform frequency conversion on the received F1 frequency point signal to the F2 frequency point when transmitting in the downlink direction; and to perform frequency conversion on the F2 frequency point signal to be transmitted at the remote end to the F1 frequency point when transmitting in the uplink direction; A synchronization signal extraction module is used to convert the baseband signal into an intermediate frequency radio frequency signal, and to perform the transceiver processing of the radio frequency signal; The customer premises equipment CPE is used to convert the received F2 frequency signal into a local wired or wireless signal; the F2 frequency is the frequency used by the operator's public network for commercial use.

8. A method applied to a 5G communication system used in a special frequency band as claimed in any one of claims 1 to 5, characterized in that: The method comprises: S201, the remote radio unit RRU receives the in-phase orthogonal IQ signal transmitted from the baseband processing unit BBU, and converts it to F1 frequency point signal through up-conversion, digital-to-analog conversion and radio frequency modulation; S202, the near-end frequency conversion module converts the intermediate frequency radio frequency signal modulated to the F1 frequency point to be transmitted to the F1 frequency point for transmission; and transmits the F1 frequency point signal through the antenna unit of the near-end unit; S203, the remote frequency conversion module receives the F1 frequency signal sent by the local frequency conversion module, performs frequency conversion to the F2 frequency signal; and sends the F2 frequency signal after frequency conversion to the customer premises equipment CPE; S204, the customer premises equipment CPE receives the F2 frequency point signal after frequency conversion sent by the remote frequency conversion module, and converts it into a local network signal, which is used by the local device to access the local network signal.

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