4G / 5G signal wireless coverage method

Abstract

The present invention provides a 4G / 5G signal wireless coverage method, including: BBU backhauls through the broadband resources of the OLT room to establish a connection with the core network; 4G / 5G downlink service data is processed by the BBU baseband and then combined with the optical signal of the PON port of the OLT through its forward transmission interface optical signal, and then transmitted to the user's residence through a two-level ODN network and then divided into two optical signals using an optical splitter, respectively to the RU unit and the ONU unit, and the RU unit converts the 4G / 5G baseband signal into a wireless signal to complete the 4G / 5G wireless signal coverage; the 4G / 5G downlink baseband signal is forwarded to the remote RU through the ODN network in a broadcasting manner; the 4G / 5G uplink IQ data is processed by the RU and converted into an optical signal, which is uploaded to the BBU in a TDMA manner, and only one RU with the same laser wavelength can send an uplink signal at any time, and different RUs are allocated different time slices to send uplink data in turn. The present invention unifies fixed-line broadband communication and wireless mobile communication without affecting each other.

Description

Technical Field

[0001] The present invention relates to the field of communications, and in particular to a 4G / 5G signal wireless coverage method. Background Art

[0002] There are two main 4G / 5G signal wireless coverage methods in the prior art:

[0003] (1) Optical modem plus integrated skin base station to achieve 4G wireless coverage for home or enterprise. Figure 1 As shown in the figure, the 4G integrated pico base station is located behind the optical modem (ONU), and supports backhaul to the core network through PTN+VLAN or IPsec to complete the opening of the 4G cell. In this mode, each family or enterprise enjoys the LTE cell exclusively. The characteristic of this mode is that the optical fiber of the original PON (Passive Optical Network: passive optical fiber network) network can be used, and the LTE cell opening can be completed without secondary wiring construction and property coordination. While providing users with home or enterprise broadband, high-quality LTE services are also provided. It is mainly used in home scenarios or some small and micro enterprise scenarios. It can not only quickly improve the indoor coverage quality of wireless signals and enhance user experience, but also divert macro station traffic and alleviate the pressure of macro network expansion.

[0004] (2) Extended skin base stations achieve 4G / 5G wireless coverage in enterprise scenarios. Figure 2 As shown in the figure, the extended pico base station is an evolution of the integrated pico base station. It adopts digital technology and is a micro-power indoor coverage solution based on optical fiber or network cable to carry wireless signal transmission and distribution. It is mainly used in low-capacity indoor scenarios and is one of the indoor coverage enhancement solutions. The extended pico base station, similar to Huawei's Lampsite and other solutions, includes a host unit (BBU), an extension unit (EU), and a radio unit (RU). By expanding the function of the host unit, the extended pico base station can easily support 4G and 5G wireless signal coverage at the same time, and the coverage unit can achieve a lower cost.

[0005] Among them, the main disadvantages of the solution of optical modem plus integrated skin base station are: (1) The integrated skin base station equipment must have a baseband chip inside, resulting in high equipment cost and power consumption; (2) The baseband chip of the integrated skin base station is currently only 3G and 4G with SOC chips, and 5G does not have a corresponding SOC chip, so it is impossible to realize 5G integrated skin base stations; (3) An integrated skin base station is an independent cell. When there are a large number of skin base stations, the relationship between neighboring cells is complicated, the core network parameters are more, and the opening, management and maintenance are complicated;

[0006] The main disadvantages of the extended skin station solution are that the extended skin station requires rewiring and construction, cannot reuse the existing home fiber optic network, requires re-coordination with the property, and the final cost of the entire network is also high. Summary of the invention

[0007] The present invention provides a 4G / 5G signal wireless coverage method to solve at least one of the above technical problems.

[0008] To solve the above problems, as one aspect of the present invention, a 4G / 5G signal wireless coverage method is provided, comprising:

[0009] The BBU uses the broadband resources in the OLT room to backhaul and establish a connection with the core network;

[0010] After the 4G / 5G downlink service data is processed by the BBU baseband, the optical signal of its fronthaul interface is combined with the optical signal of the PON port of the OLT before the first-level ODN, and then transmitted to the user's residence through the two-level ODN network. Then, the optical splitter is used to split the optical signal into two optical signals, which are respectively given to the RU unit and the ONU unit. The RU unit converts the 4G / 5G baseband signal into a wireless signal for transmission to complete the 4G / 5G wireless signal coverage;

[0011] The 4G / 5G downlink baseband signal is forwarded to the remote RU through the ODN network in a broadcast manner;

[0012] The 4G / 5G uplink IQ data is processed by the RU and converted into an optical signal, which is then uploaded to the BBU via TDMA. Only one RU can send an uplink signal at any one time. Different RUs are allocated different time slices and take turns sending uplink data. The sending position is allocated by the BBU. The 4G / 5G uplink signal is uploaded from the RU to the BBU via the ODN network in TDMA mode.

[0013] Preferably, the fronthaul interface of the 4G / 5G BBU performs downstream combining and upstream branching through an optical splitter and combiner device and the optical signal of the PON port of the OLT, wherein the downstream uses one wavelength and is staggered with the downstream laser wavelength used by the PON network; the upstream uses two wavelengths and is staggered with the upstream laser wavelength used by the PON network, and the optical splitter and combiner device supports the downstream combining and upstream branching of these wavelengths. The upstream can also use one or more wavelengths, depending on the system's demand for upstream bandwidth and the transmission rate that the devices used in the system can support. However, each independent RU generally uses one upstream wavelength, and the BBU can use one or more upstream wavelengths as needed.

[0014] Preferably, the BBU downlink signal is combined with the PON signal through the optical splitter / combiner device and then transmitted to the user through the secondary ODN broadcast. At the user, the downlink signal passes through an optical splitter unit to distribute the downlink signal to the ONU and RU.

[0015] Preferably, the optical splitter unit can be integrated in the RU unit, and the RU unit splits the fiber and connects it to the ONU. The optical splitter unit can also be a separate component and is not placed inside the RU or ONU device.

[0016] Preferably, the RU at the user's location first converts the 4G or 5G uplink wireless signal sent by mobile phones and other terminal users into a digital IQ signal through antenna reception, RF signal processing, digital signal processing, etc., and then converts it into an optical signal through framing, parallel-to-serial conversion, electro-optical conversion, etc., and transmits it upward through the ODN network to the BBU in time-sharing according to the time slots assigned by the BBU.

[0017] Preferably, RUs with the same laser transmission wavelength at different users are sent in turn according to the time slot specified by the BBU, that is, the TDMA mode is adopted. The transmission time slot of each RU is completely independent and cannot be sent at the same time, and has a certain protection interval; RUs with different uplink laser transmission wavelengths can be transmitted at the same time; BBU performs precise ranging and delay compensation for RU so that RU can reach the BBU on time in the specified time slot.

[0018] Preferably, diversity reception combining is performed at the RU to save uplink transmission bandwidth, and before framing, the uplink digital IQ signal can be compressed to reduce the uplink transmission bandwidth.

[0019] Preferably, the BBU determines the uplink time slot allocation scheme of the RU based on the maximum transmission bandwidth supported by the fronthaul optical interface and the uplink transmission bandwidth requirement of the RU. The maximum transmission rate of the RU's optical interface is equal to the maximum reception rate supported by the BBU's optical interface. The BBU can add uplink receiving optical interfaces with different laser wavelengths to multiply the supported uplink transmission bandwidth, but each RU may only need one uplink laser wavelength, while the system can have several RUs with different uplink laser wavelengths.

[0020] Preferably, the uplink signal from the RU is connected to different optical ports of the BBU after passing through the optical splitter-combiner device, and different wavelengths are connected to different optical ports; the RU uplink signal reaching the BBU is subjected to optoelectronic conversion, serial-to-parallel conversion, deframing, decompression, and conditional merging of uplink digital IQ signals of different RUs, and then given to the baseband processing unit for uplink signal demodulation and other processing.

[0021] The co-fiber transmission method of the PON network optical signal and the 4G / 5G wireless optical signal of the present invention unifies two main communication modes: fixed-line broadband communication and wireless mobile communication, but does not affect each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The schematic diagram of the method of realizing 4G wireless coverage of home or enterprise by using an optical modem and an integrated Pico station in the prior art is schematically shown;

[0023] Figure 2 The schematic diagram of the method for realizing 4G / 5G wireless coverage in enterprise scenarios by using an extended skin base station in the prior art is schematically shown;

[0024] Figures 3(a) and 3(b) schematically show the schematic diagrams of the 4G / 5G signal wireless coverage method in the present invention, wherein the BBU can also be placed at other PON ports, or other PON ports share a baseband cell, etc. DETAILED DESCRIPTION

[0025] The following is a detailed description of embodiments of the present invention, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0026] The present invention provides a method for front-transmitting 4G / 5G signals to achieve wireless coverage based on PON (Passive Optical Network: Passive Optical Network) network ODN optical fiber wiring resources, the purpose of which is to provide a method for front-transmitting 4G / 5G signals based on the existing PON network ODN optical fiber wiring resources to achieve high-efficiency and high-quality coverage of wireless signals (as shown in Figures 3(a) and 3(b)).

[0027] WDM: Wavelength Division Multiplexing

[0028] OLT:Optical line terminal;

[0029] ONU:Optical Network Unit;

[0030] PON: Passive Optical Network;

[0031] ODN:Optical Distribution Network(optical distribution network).

[0032] The method provided by the present invention for realizing wireless coverage by front-transmitting 4G / 5G signals based on ODN resources of PON network can make full use of the existing PON network optical fiber wiring to households, and can realize high-quality, low-cost, simple and fast 4G / 5G wireless signal coverage, and can achieve effects such as on-demand coverage and precise coverage.

[0033] The BBU of the present invention can be implemented by chips such as SOC chip + FPGA + ARM CPU. The baseband SOC chip mainly implements L1 processing. It can use 4G and 5G independent baseband SOC chips, or use a baseband SOC chip that supports both 4G and 5G; the ARM CPU mainly implements L3, L2 and other protocol stack processing and OM and other platform software functions. The FPGA chip mainly implements baseband IQ signal processing and interface expansion, and can support multiple optical ports externally. Some 4G baseband chips are equipped with ARM CPU, and the L3, L2, L1 and other protocol stack processing and OM and other platform software functions of 4G base stations can be implemented by a single chip.

[0034] The present invention supports simultaneous coverage of 4G and 5G wireless signals. Considering the maturity of the current 5G baseband solution and other issues, 4G and 5G coverage can also be achieved in stages. When 4G and 5G coverage is achieved in stages, the early BBU unit only supports 4G baseband signals. When 5G is needed, a 5G extended signal source must be added. The 5G extended signal source can be introduced through an extended optical port of the 4G BBU. The 4G BBU can complete the functions related to the extended unit in the NR system. The RU can currently support 4G+5G dual-mode coverage.

[0035] The RU in the present invention can support 4G / 5G dual-mode in the same frequency band, such as the N1 frequency band (4G occupies 20MHz bandwidth, 5G occupies 40MHz bandwidth, etc.); it can also support 4G / 5G dual-mode in different frequency bands, such as the N3 frequency band (4G occupies 20MHz bandwidth) and the N78 frequency band (5G occupies 100MHz bandwidth). Other combinations of frequency bands or bandwidths can also be supported. The RU of the present invention can support applications such as N1 frequency band 4T2R, 4T1R, 2T2R, 2T1R, and can also support N1 frequency band 4T4R applications, or N1 frequency band 2T2R plus N78 frequency band 2T2R and other applications. These application combinations are mainly determined by the limitations on the uplink transmission bandwidth caused by cost constraints. The transmission bandwidth is small, the optical module rate is low, and the relative cost will be low. When the transmission bandwidth is too high, it may exceed the processing capacity of current general-purpose devices, resulting in a huge increase in equipment costs, or even making it difficult to achieve. For example, the need to achieve 4T4R coverage of the N1 band (full bandwidth 60MHz) and the N78 band (bandwidth 200MHz) becomes unrealistic for residential home devices. Not only is the cost of a single RU high, but the upstream transmission bandwidth requirement is greater than 26Gbps, which is difficult to support with the current PON network architecture. In particular, it is basically impossible to achieve online transmission of dozens of home RUs at the same time.

[0036] In a preferred embodiment of the present invention, the BBU is backhauled through the IPRAN of the OLT room and other means to establish a connection with the core network; the 4G / 5G downlink service data is processed by the BBU baseband and then combined with the optical signal of the PON port of the OLT through its forward transmission interface optical signal, and then transmitted to the user's residence through the passive optical fiber network, and then divided into two optical signals using an optical splitter, which are respectively given to the RU unit and the ONU unit. The RU unit converts the 4G / 5G baseband signal into a wireless signal for transmission to complete the 4G / 5G wireless signal coverage. The 4G / 5G downlink baseband signal is forwarded to the remote RU through the ODN network in a broadcast manner. This is similar to the downlink data propagation method of the PON network.

[0037] The 4G / 5G uplink IQ data is processed by the RU and converted into an optical signal, which is then uploaded to the BBU via TDMA. Only one RU can send an uplink signal at any one time for the system to work properly. Different RUs are assigned different time slices and take turns sending uplink data. The sending position is assigned by the BBU. The 4G / 5G uplink signal is uploaded from the RU to the BBU via the ODN network in TDMA. This is similar to the uplink data transmission method of the PON network, but the upload bandwidth requirement of the RU is much greater than the upload bandwidth requirement of the ONU, and the total upload bandwidth of all ONUs is generally less than the downlink bandwidth, at most equal to the downlink bandwidth, while the total upload bandwidth of all RUs is much greater than the downlink bandwidth, at least more than one order of magnitude; for example, if the BBU downlink bandwidth is 6.25Gbps, then the uplink bandwidth required by the BBU may be 62.5Gbps.

[0038] It should be noted that the current common BBU+RU architecture also basically adopts the broadcast mode in the downlink direction, but the uplink direction directly adopts the convergence superposition mode rather than the TDMA mode, so that the optical transmission rates of the downlink and uplink are the same, and the transmission bandwidths of the uplink and downlink are equal. For the present invention, the total rate in the uplink direction depends on the number of remote RUs and the total bandwidth of the uplink RF signal. The uplink and downlink rates are not consistent, and the total transmission bandwidth required for the uplink is much larger than the transmission bandwidth required for the downlink. For example, taking the 2T2R application of 4G / 5G wireless coverage supporting N1 frequency band (60MHz bandwidth) as an example, the downlink from BBU to RU requires 3Gbps transmission bandwidth, and the uplink from each RU to BBU also requires 3Gbps. According to the 1:64 splitting of the PON network, each PON port of the OLT can carry 64 ONUs, and the corresponding BBU fronthaul interface can also support 64 RUs. Considering that the uplink data of each RU is different and requires independent bandwidth, the total bandwidth required for the uplink is 192Gbps; according to the 1:32 splitting of the PON network, 32 RUs can be supported, and the total bandwidth required for the uplink is 96Gbps. If the interconnection optical port of the BBU and RU supports a 25Gbps optical interface, then the optical port of a BBU can support at least 8 RUs and occupy one wavelength; to support 32 RUs, 4 optical ports are required, and 4 wavelengths are occupied, so there are 4 types of RUs. The RUs under each PON port must be divided into 4 groups with different uplink wavelengths, which is more complicated to manage and maintain.

[0039] The present invention, through compression algorithm and compression of uplink radio frequency bandwidth, can control the wavelengths required for uplink to 2, and at the same time can control the uplink instantaneous transmission rate of a single RU to below 12.5Gbps, and even adopt an uplink instantaneous transmission rate of 6.25Gbps, which can greatly reduce the implementation cost of RU and reduce the complexity of management and maintenance of the entire system.

[0040] The detailed steps of this method are as follows:

[0041] Step 1: Combine the 4G / 5G BBU's fronthaul interface through an optical splitter / combiner (WDM) and the PON signal of the OLT for downstream combination and upstream branching. The downstream uses one wavelength (such as 1550), which is staggered with the downstream laser wavelength (1490&1577) used by the PON network; the upstream uses two wavelengths (such as 1330&1350), which are staggered with the upstream laser wavelength (1270&1310) used by the PON network. The optical splitter / combiner supports downstream combination and upstream branching of these wavelengths. As shown in Figure 3(a) and Figure 3(b), λ3 is the downstream laser wavelength used by the BBU, and λ4 is the upstream laser wavelength used by the BBU. Two wavelengths can be used for the upstream, which can support more RU units. By increasing the number of upstream wavelengths, the number of RUs supported by the system can be doubled.

[0042] Step 2: The BBU downlink signal is combined with the PON signal through the optical splitter and combiner and then broadcasted to the user through the ODN network. At the user, the downlink signal is distributed to the ONU and RU through an optical splitter unit. To facilitate the installation of RU equipment by existing ONU users, the optical splitter unit can be integrated into the RU unit, and the RU unit is connected to the ONU by fiber splitter. The optical splitter unit can also be completely independent as a component. The baseband downlink IQ signal reaching the RU is converted into a wireless signal through interface conversion, digital signal processing, RF signal processing, antenna radiation, etc. to complete wireless coverage.

[0043] In step 3, the RU at the user's location converts the 4G or 5G uplink wireless signal sent by the mobile phone and other terminal users into a digital IQ signal through antenna reception, RF signal processing, digital signal processing, etc., and then converts it into an optical signal through framing, parallel-to-serial conversion, electro-optical conversion, etc., and transmits it to the BBU through the ODN network in time-sharing according to the time slot assigned by the BBU.

[0044] RUs with the same laser transmission wavelength at different users are sent in turn according to the time slot specified by the BBU, that is, the TDMA mode is adopted. The transmission time slot of each RU is completely independent and cannot be sent at the same time, and there is a certain protection interval. RUs with different uplink laser transmission wavelengths can be transmitted at the same time. The BBU needs to perform accurate ranging and delay compensation for the RU so that the RU can reach the BBU on time in the specified time slot.

[0045] In order to save uplink transmission bandwidth, diversity reception and merging can be performed at the RU, so that the uplink transmission bandwidth is immediately halved; at the same time, the uplink digital IQ signal can be compressed before framing, which can further reduce the transmission bandwidth. For example, the 2R signal with a bandwidth of 60MHz in the B1 frequency band can be transmitted at a transmission bandwidth of more than 600Mbps after the above diversity merging and compression processing; the transmission bandwidth of 25Gbps can transmit uplink data of about 40 RUs, and so on. The transmission bandwidth of 12.5Gbps can transmit uplink data of about 20 RUs, and so on.

[0046] The BBU determines the uplink timeslot allocation scheme for the RU based on the maximum transmission bandwidth supported by the fronthaul optical interface and the uplink transmission bandwidth requirement of the RU. The maximum transmission rate of the RU is equal to the maximum reception rate supported by the BBU.

[0047] Step 4: The RU uplink signal is connected to different optical ports of the BBU after passing through the optical splitter / combiner. The RU uplink signal reaching the BBU undergoes optoelectronic conversion, serial-to-parallel conversion, deframing, decompression, and conditional merging of uplink digital IQ signals of different RUs before being sent to the baseband processing unit for uplink signal demodulation and other processing.

[0048] The present invention has the following beneficial effects and advantages:

[0049] 1. It can realize "PON is wireless", and can make full use of the ODN fiber cabling resources of the existing PON network. Where there is a PON network, 4G / 5G wireless coverage can be quickly achieved. Compared with the newly built extended skin base stations of 4G / 5G, it has quick and simple construction and low overall network cost. For high-rise residential buildings, urban villages, first-floor shops and other scenes that are difficult to optimize the network, "PON is wireless" is a very simple, convenient, efficient and high-quality solution.

[0050] 2. The home unit does not require a dedicated 4G or 5G baseband chip. The equipment for achieving 4G / 5G wireless coverage is relatively simple, consumes less power, is low in cost, can be plug-and-play, and is easy to popularize and promote. Compared with the 4G integrated pico base station, the present invention requires fewer base station cells, has simple neighboring cell relationships, less cell interference, requires fewer core network parameters, and has a small workload for opening, management, and maintenance.

[0051] 3. For residential users, wireless repeaters similar to mobile phone companions can also be used to solve the problem of wireless signal coverage. However, compared with the present invention, the former equipment is not easy to control, the quality of wireless signals cannot be guaranteed and may cause interference to macro stations. The equipment cost is not cheap and is only used for very few customer complaints, which is not convenient for large-scale promotion and application.

[0052] The method of using ODN optical fiber cabling resources based on the PON network to front-transmit 4G / 5G signals to achieve wireless coverage in the present invention is significantly different from the solution of pulling fiber into homes alone, and is also different from the integrated small station that directly uses ONU backhaul. On the one hand, there is no SOC single chip that supports 4G / 5G baseband yet, and at the same time, backhaul will occupy the ONU bandwidth, which may affect the broadband services supported by the ONU itself.

[0053] The co-fiber transmission method of the PON network optical signal and the 4G / 5G wireless optical signal of the present invention unifies the two main communication modes: fixed-line broadband communication and wireless mobile communication, but does not affect each other, and has the following characteristics:

[0054] (1) The 4G / 5G baseband signals are combined by optical splitter / combiner at the PON port of the OLT, and then split by optical splitter at the user end, so as to share the ODN optical fiber cabling resources of the PON network to transmit the digital baseband IQ signals between the BBU unit and the RU unit;

[0055] (2) The network architecture between BBU and RU is completely different from the current general architecture. This is mainly reflected in the fact that the uplink from RU to BBU adopts the TDMA mode. The uplink data of each RU is not sent in the full time slot, but only in the partial time slot allocated by the BBU.

[0056] (3) The RU uplink wavelength can be classified and adopted into different wavelengths, which can reduce the uplink transmission rate requirements by several times and reduce the processing speed of the RU devices themselves, thereby significantly reducing the cost of the RU.

[0057] (4) The user end uses a single-fiber single-mode module and a 1-to-2 splitter to combine and split laser signals of different wavelengths, making full use of the single-fiber single-mode optical module's ability to suppress laser signals of other wavelengths that it does not use, avoiding the crosstalk problem of optical fiber transmission of laser signals of different wavelengths, thereby ensuring the quality of the PON network itself. To ensure that the operation of the existing PON network is not affected, the splitter ratio can be adjusted so that the optical attenuation to the ONU is small, and the wireless link itself can adapt to the optical attenuation of the splitter by controlling the performance of the optical module.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A 4G / 5G signal wireless coverage method, characterized in that: include: The BBU uses the broadband resources in the OLT room to backhaul and establish a connection with the core network; After the 4G / 5G downlink service data is processed by the BBU baseband, the optical signal of its fronthaul optical interface is optically split and combined with the optical signal of the PON port of the first-level ODN, and then transmitted to the user's residence through the two-level ODN network. Then, the optical splitter unit is used to split the optical signal into two optical signals, which are respectively given to the RU unit and the ONU unit. The RU unit converts the 4G / 5G baseband signal into a wireless signal for transmission to complete the 4G / 5G wireless signal coverage; The 4G / 5G downlink baseband signal is forwarded to the remote RU through the ODN network in a broadcast manner; The 4G / 5G uplink IQ data is processed by the RU and converted into an optical signal, which is then uploaded to the BBU via TDMA. At any given time, only one RU with the same laser wavelength can send an uplink signal. Each RU is assigned a different time slot and takes turns sending uplink data. The sending position is assigned by the BBU. The 4G / 5G uplink signal is uploaded from the RU to the BBU via the ODN network in TDMA mode. RUs with the same laser wavelength at different users take turns sending data in the time slot specified by the BBU, that is, the TDMA mode is adopted. The sending time slot of each RU is completely independent and cannot be sent at the same time, and has a certain protection interval. RUs with different uplink laser wavelengths can transmit at the same time. The BBU performs precise ranging and delay compensation on the RU so that the RU can reach the BBU on time in the specified time slot. The fronthaul optical interface of 4G / 5G BBU performs downstream combining and upstream splitting through an optical splitter / combiner device and the PON signal of the OLT, wherein one laser wavelength is used for the downstream and staggered with the downstream laser wavelength used by the PON network; two laser wavelengths are used for the upstream and staggered with the upstream laser wavelength used by the PON network, and the optical splitter / combiner device supports the downstream combining and upstream splitting of these laser wavelengths; the number of laser wavelengths used for the upstream depends on the number of RUs that the system needs to support and the RF bandwidth of the RUs that need to upload signals; The BBU determines the uplink time slot allocation scheme of the RU based on the maximum transmission bandwidth supported by the fronthaul optical interface and the uplink transmission bandwidth requirement of the RU. The maximum transmission rate of the RU's optical interface is equal to the maximum reception rate supported by the BBU's optical interface. The BBU can add uplink receiving optical interfaces with different laser wavelengths to multiply the supported uplink transmission bandwidth. However, each RU only needs one uplink laser wavelength, while the system has several RUs with different uplink laser wavelengths.

2. The 4G / 5G signal wireless coverage method according to claim 1, characterized in that: The optical splitter unit is integrated in the RU unit, and the RU unit splits the fiber and connects it to the ONU; or, the optical splitter unit is an independent component and is not placed inside the RU or ONU equipment.

3. The 4G / 5G signal wireless coverage method according to claim 1, characterized in that: The RU at the user's location converts the 4G or 5G uplink wireless signal sent by the terminal user into a digital IQ signal through antenna reception, RF signal processing, and digital signal processing. It is then converted into an optical signal through framing, parallel-to-serial conversion, and electro-optical conversion and transmitted upward to the BBU through the ODN network in time-sharing according to the time slots allocated by the BBU.

4. The 4G / 5G signal wireless coverage method according to claim 3, characterized in that: Diversity reception combining is performed at the RU to save uplink transmission bandwidth. At the same time, the uplink digital IQ signal can be compressed before framing to reduce the transmission bandwidth.

5. The 4G / 5G signal wireless coverage method according to claim 1, characterized in that: The RU uplink signal is connected to different optical ports of the BBU after passing through the optical splitter and combiner equipment. The RU uplink signal reaching the BBU undergoes optoelectronic conversion, serial-to-parallel conversion, deframing, decompression, and conditional merging of uplink digital IQ signals of different RUs before being sent to the baseband processing unit for uplink signal demodulation.

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