CN108768507B

CN108768507B - Link switching method and system for RRU (radio remote unit) ring network

Info

Publication number: CN108768507B
Application number: CN201810556850.8A
Authority: CN
Inventors: 汪剑雄; 陈付齐; 徐宁; 杨浩
Original assignee: Wuhan Hongxin Telecommunication Technologies Co Ltd
Current assignee: CICT Mobile Communication Technology Co Ltd
Priority date: 2018-06-01
Filing date: 2018-06-01
Publication date: 2020-06-05
Anticipated expiration: 2038-06-01
Also published as: CN108768507A

Abstract

The invention discloses a link switching method and a link switching system for RRU (radio remote unit) ring network, which comprises the steps that the RRU respectively acquires configuration parameters of two optical ports from a BBU (base band unit) in advance and stores the configuration parameters; the cascade RRU adopts optical port out-of-order to start and establish a normal service link with the BBU; and the RRU detects the link fault, bidirectionally and respectively transmits the link fault to the BBU and the rear-stage RRU, and the rear-stage RRU switches an optical port to establish a link with the other optical port of the BBU to complete link switching. The invention can be used for improving the flexibility of engineering networking and rapidly switching the link to ensure the service continuity when the link fails.

Description

Link switching method and system for RRU (radio remote unit) ring network

Technical Field

The present invention relates to the field of mobile communications, and in particular, to a method and a system for link switching in RRU ring networking.

Background

The LTE base station equipment generally adopts a distributed base station architecture, and is composed of a BBU and an RRU, and the BBU and the RRU are generally connected by an optical fiber and are often networked in a star or chain manner. Under a chain type networking mode, a plurality of stages of RRUs are connected with one optical port of a BBU in a serial mode to provide a cascade service channel. However, the chain type network has a disadvantage of poor reliability, and if a fault occurs on a link, all RRUs at the rear stage of the fault point are disconnected from the BBU, and thus cannot provide services.

In order to solve the above problems, the Ir interface technology proposes a concept of ring networking, that is, another optical port of the cascaded last-stage RRU is connected to another optical port of the BBU. When the link direction is failed, the link establishment from the reverse direction can be switched, and the service transmission is continuously provided. However, the method proposed by the existing Ir interface technology is to detect the fault by using a single heartbeat, and using RRU

The reset mode is accessed again to establish a reverse link, and the time required in the middle reaches the minute level, so that the service is dropped, and the user requirements cannot be met. In addition, in ring networking, the existing scheme is usually to fixedly start and establish a link from one optical port (main optical port), and the other optical port (auxiliary optical port) is used as a backup, so that engineering networking is not flexible enough.

The commonly used technical terms are explained as follows:

1. BBU: base width Based Unit, Baseband processing Unit

2. RRU: remote RF Unit

3. LTE: long Term Evolution (LTE) plan for Long Term Evolution (Long Term Evolution)

4. Ir: interface between the RRU and the BBU, and Interface between BBU and RRU

5. LOS: lost of signal

6. LOF: lost of signal, frame

7. LOP: lost of Power

8. IP: internet Protocol, Internet Protocol

9. FPGA: field Programmable Gate Array

Disclosure of Invention

The invention provides a method and a system for establishing and switching links of an RRU (radio remote unit) ring network, aiming at the problems of poor engineering networking flexibility, single fault detection means, untimely response and service drop during link switching in the prior art of an LTE (long term evolution) distributed base station.

The invention provides a link switching method of RRU ring network, comprising the following processes,

the RRU respectively acquires configuration parameters of two optical ports from the BBU in advance and stores the configuration parameters;

the cascade RRU adopts optical port out-of-order to start and establish a normal service link with the BBU;

and the RRU detects the link fault, bidirectionally and respectively transmits the link fault to the BBU and the rear-stage RRU, and the rear-stage RRU switches an optical port to establish a link with the other optical port of the BBU to complete link switching.

Moreover, the RRU acquires and stores configuration parameters of two optical ports, and the implementation mode is,

the BBU opens the optical port 1, closes the optical port 2, all the RRUs are accessed through the optical port 1, the BBU respectively allocates different IP addresses to each stage of RRU, and the measured delay value of each stage is sent to the corresponding RRU for delay compensation, and each stage of RRU stores the corresponding IP address and delay value;

the BBU starts an optical port 2, closes an optical port 1, resets all RRUs, accesses all the RRUs through the optical port 2 after resetting, allocates different IP addresses to each stage of RRU by the BBU respectively, and distributes the measured delay value of each stage to the corresponding RRU for delay compensation, and each stage of RRU stores the corresponding IP address and delay value;

the cascaded RRUs are connected to the main optical port in a disorder starting mode, and each stage of RRU stores the antenna, the cell and IQ data of the RRU.

Moreover, the configuration parameters include the IP address and uplink and downlink delay values of the RRU corresponding to the optical port 1, the IP address and uplink and downlink delay values of the RRU corresponding to the optical port 2, and the antenna, the cell, and the IQ data after the normal access to the main optical port.

And the RRU adopts different IP addresses corresponding to different optical ports, thereby realizing a dual-IP mechanism of the RRU optical ports.

Moreover, the implementation of the RRU optical port out-of-order start is as follows,

the FPGA in the RRU inquires the detection power of the optical module, the result is stored in a register of the RRU, and the processor reads the register of the FPGA to obtain the result;

setting the main optical port as the optical port with power, if all optical ports are available, setting the optical port 2 as the main optical port if the optical ports are marked as 2, otherwise, setting the optical port 1;

the FPGA analyzes whether the synchronous code is received from the Ir interface protocol data, the result is stored in a register of the FPGA, and the processor reads the register of the FPGA to obtain the result;

and if the RRU is synchronous, the RRU sends broadcast access to the BBU, parameter configuration is carried out to complete link establishment, otherwise, if the auxiliary optical port has power, the storage optical port identification is modified, the RRU is reset, and if the auxiliary optical port has no power, the RRU is reset.

Moreover, the RRU link failure detection is realized by the following method,

the RRU comprises an optical module, the optical module has a status indication for LOS/LOP faults, the FPGA acquires the faults through monitoring the status indication in real time, and for the LOF faults, the FPGA analyzes frame synchronization information from a data packet according to an Ir interface protocol so as to acquire the LOF status and inform a processor of the LOF status for processing.

Moreover, the RRU link failure information transmission is realized as follows,

when the front-stage RRU of the fault point detects an uplink fault, the FPGA synthesizes uplink fault information into a physical layer control word of an Ir interface protocol, the uplink fault information is transmitted to the BBU through all the front-stage RRUs in an uplink mode, when the rear-stage RRU of the fault point detects a downlink fault, the FPGA synthesizes downlink fault information into a physical layer control word of the Ir interface protocol, and the downlink fault information is transmitted to the rear-stage RRU in a downlink mode.

Moreover, the mode of switching after RRU link failure is as follows,

after a main optical port of the BBU receives fault information transmitted by the RRUs through an uplink of a forward link, the auxiliary optical port is controlled to send service data which are the same as those of the fault rear-stage RRUs, then the service data sent to the fault rear-stage RRUs on the original main optical port are deleted, after all the RRUs in the fault rear stage receive downlink fault information, the main optical port and the auxiliary optical port of the RRU are switched, a pre-stored time delay value and an IP address are correspondingly replaced, pre-stored antennas, pre-stored cells and pre-stored IQ data are adopted to be configured unchanged, and the auxiliary optical ports of the BBU are accessed in a reverse mode to perform communication interaction and keep services continuous.

The invention also provides an RRU ring networking system, which comprises a ring network topology structure consisting of a BBU and a plurality of RRUs, wherein the RRUs are accessed from the main optical port in the forward direction, and when a link fails, service data is kept unchanged, and the link switching after the failure is carried out; and the BBU provides a main optical port data service for all the RRUs, and after a fault occurs, the service data which is the same as that of the main optical port is provided for the auxiliary optical port of the RRU at the rear stage of the fault.

Furthermore, the BBU comprises the following units,

a parameter generating unit, configured to establish service links with RRUs from two optical ports in advance, respectively, and generate configuration parameters related to services of the RRUs at each stage, where the configuration parameters include: different optical port IPs of the BBU, the IPs of each stage of RRU, uplink and downlink delay values, antennas, cells and IQ data;

the optical interface link establishing unit is used for establishing a complete data service link with the RRU when the RRU is started out of order;

the fault acquisition unit is used for receiving fault information transmitted by a forward link uplink from the RRU when a link fails so as to trigger the optical interface processing unit;

and the optical port processing unit is used for processing the optical port after receiving the trigger of the fault acquisition unit: and the auxiliary optical port reversely sends the service data of the original main optical port of the fault rear-stage RRU, deletes the service data sent to the fault rear-stage RRU by the main optical port, and adopts an auxiliary optical port IP to communicate with the fault rear-stage RRU.

Furthermore, the RRU comprises the following units,

the parameter storage unit corresponds to the parameter generation unit of the BBU and is used for storing the parameters generated by the parameter generation unit for the link switching unit to use;

the out-of-order link establishing unit is used for establishing a normal service data link with the BBU according to the method for starting the RRU optical interface out-of-order;

the fault detection unit is used for completing the fault detection of the link established by the out-of-order link establishment unit according to the RRU fault detection method, and sending the result to the fault processing unit;

and the fault processing unit is used for transmitting the fault information on the link according to the RRU fault transmission method and switching the link according to the RRU link fault post-switching method to keep the service continuity.

Furthermore, the fault detection unit comprises a unit,

the fault transfer unit is used for synthesizing the detection result of the fault detection unit into a physical layer control word, and transmitting the physical layer control word to a superior level along a forward link and transmitting the physical layer control word to a subordinate level along a forward link;

and the link switching unit is used for switching the main optical interface and the auxiliary optical interface of the link switching unit, replacing the parameters of the parameter storage unit and establishing a reverse link with the BBU auxiliary optical interface.

The invention has the following advantages and positive effects:

1. the disordered cascade starting of the RRU optical ports is supported, so that the engineering networking is more flexible, and the fault tolerance of the system is improved;

2. LOS/LOF/LOP multiple link fault detection is carried out, and the detection is transmitted through a physical layer, so that the detection is more rapid and accurate;

3. the forward link and the reverse link RRU adopt a double IP mechanism, and the link switching is faster and more effective.

Drawings

Fig. 1 is a schematic diagram of a prior art ring networking.

Fig. 2 is a schematic diagram of RRU out-of-order cascaded ring networking according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of an overall method according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a method for obtaining two optical parameters in advance according to an embodiment of the present invention.

Fig. 5 is a schematic diagram of an RRU optical port out-of-order cascade connection start process according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of a RRU ring networking link failure according to an embodiment of the present invention.

Fig. 7 is a schematic flow chart of fault detection and link switching according to an embodiment of the present invention.

Fig. 8 is a functional structure schematic diagram of a BBU and an RRU according to an embodiment of the present invention.

Detailed Description

The invention is further described with reference to the following figures and examples.

Referring to fig. 1, a structure diagram of a lower ring network in the prior art is shown, where an RRU is fixedly connected to an optical port 1 for establishing a link, and fig. 2 is a structure diagram of an RRU optical port out-of-order cascaded ring network shown in the embodiment of the present invention, it should be noted that, first, although the embodiment is 4-stage RRU cascaded, in practice, the number of cascaded RRUs may be increased or decreased appropriately according to the traffic volume; second, fig. 2 is a reverse connection of the RRU2 and the RRU4 optical ports, and in fact, all the RRU optical ports can be connected at will, i.e., so-called out-of-order concatenation.

The general method of an embodiment of the invention is briefly described as follows, with reference to fig. 3:

step S31, respectively acquiring parameters of the two optical ports, and storing the parameters in advance;

step S32, starting access by disorder cascade connection, and establishing a link;

and step S33, detecting link failure and finishing switching.

Next, a detailed description is given of the above steps, respectively.

In order to keep the service continuous, when the link fails, the switching time needs to be as short as possible, and if the configuration parameters are re-acquired through communication interaction with the BBU after the link is broken, the time is too long, so the configuration parameters are acquired in advance and stored to accelerate the switching speed, and the configuration parameters comprise: the IP address and uplink and downlink delay values of the RRU corresponding to the optical port 1, the IP address and uplink and downlink delay values of the RRU corresponding to the optical port 2, and the antenna, cell and IQ data after normally accessing the main optical port. With reference to fig. 2 and 4, the method in the embodiment is described, which includes the following steps:

step S41, corresponding to fig. 2, the BBU opens the optical port 1, closes the optical port 2, and accesses the 4-stage RRUs through the optical port 1, the BBU allocates different IP addresses to each stage of RRUs, and distributes the measured delay value of each stage to the corresponding RRUs for delay compensation, and each stage of RRUs stores the corresponding IP addresses and delay values;

step S42, corresponding to fig. 2, the BBU opens the optical port 2, closes the optical port 1, the BBU resets 4 stages of RRUs, the RRUs access through the optical port 2 after the resetting, the BBU allocates different IP addresses to each stage of RRUs, and distributes the measured delay value of each stage to the corresponding RRUs for delay compensation, and each stage of RRUs stores the corresponding IP address and delay value;

step S43, the cascaded RRUs access the main optical port through a disorder starting manner, and each stage of RRUs stores its own antenna, cell, and IQ data, and the disorder starting will be described in detail later.

It should be noted that, in the above method, the present invention implements a RRU dual IP mechanism, and when a failure occurs, the link can be quickly switched and then the link can still maintain normal communication with the BBU. In addition, in the present invention, through step S43, only one set of antenna, cell, and IQ data parameters corresponding to the forward link after the link is normally established are saved, instead of saving two sets (not saving parameters of the reverse link), so as to ensure that the service data remains unchanged after the link failure occurs and the link is switched.

The method for starting and establishing the link out of order by flexibly networking the optical ports comprises the following steps: detecting whether the two optical ports have optical power or not; judging and setting one of the two optical ports as a main optical port; accessing from the set main optical port broadcast; and the BBU issues parameter configuration to complete link establishment. With reference to fig. 5, the RRU optical port out-of-order starting method provided in the embodiment of the present invention is described as follows, and the method includes the following steps:

step S51, the RRU detects the optical power of the two optical ports respectively, the specific implementation is that the FPGA detects the power by inquiring the optical module, the result is stored in the register of the RRU, the processor of the RRU obtains the result by reading the FPGA register, when the two optical ports have no power, the RRU is executed in the step, otherwise, the RRU executes the next step;

step S52, setting one of the optical ports as a main optical port according to the existence of power of the optical port and the stored optical port identifier, specifically, determining the main optical port according to the result obtained in step S51 and the read optical port identifier value, where the determination principle is as follows: if the optical port 1 and the optical port 2 both have power, then if the optical port identification value is 2, the optical port 2 is set as a main optical port, otherwise, the optical port 1 is set as a main optical port; if only the optical port 1 has power, setting the optical port 1 as a main optical port, and setting the optical port identifier as 1 for storage; if only the optical port 2 has power, setting the optical port 2 as a main optical port, and setting the optical port identifier as 2 for storage;

in specific implementation, the optical port identification value may be saved in power-down mode, for example, the initial value of the optical port identification value is the default value 0xFF of the storage device.

Step S53, detecting whether the main optical interface is synchronous, specifically, whether the FPGA receives a synchronous code is analyzed from Ir interface protocol data by the FPGA, storing the result in a register of the RRU, acquiring the result by reading the FPGA register by the processor of the RRU, if the result is synchronous, performing step S54, otherwise, performing step S55;

step S54, if the precondition is that the result is synchronous in S53, the RRU sends broadcast access to the BBU, performs parameter configuration to complete link establishment, specifically sends a broadcast packet access request BBU to allocate an IP address to the RRU, performs link delay calibration, antenna, cell and IQ data configuration, and completes link establishment;

step S55, if the result in S53 is step out, determining whether the auxiliary optical port has optical power by the method (in step S51), and if so, performing step S56, otherwise, performing step S57;

step S56, if the result of S55 is power, modifying and storing the optical port identifier, specifically: if the auxiliary optical port is the optical port 1, the optical port identification is changed into 1 and written into the memory for storage, otherwise, the optical port identification is changed into 2 and written into the memory for storage;

and step S57, if the result of S55 is no power or S56 is finished, restarting the RRU, and returning to S51 to continue execution.

The method for switching the link failure under the ring network provided by the invention comprises the following steps:

the RRU respectively establishes a link from two optical ports of the BBU, acquires configuration parameters including an IP address and a time delay parameter, and stores the configuration parameters;

the RRU starts to establish a service link, called a forward link for short, from any optical port of the BBU, and records the antenna, the cell and IQ parameters on the link;

the RRU detects a link fault LOS/LOF/LOP;

all RRUs in the later stage of the fault carry out optical port switching, and the IP address and the time delay parameter are changed into the corresponding stored values;

the switched link is called a reverse link, and the switched link adopts the antenna, the cell and the IQ parameters recorded by the forward link to communicate with the other optical port of the BBU, so that the service is maintained.

In the embodiment of the present invention, LOS/LOF/LOP are used in multiple ways to determine link failure, and the detection is more accurate and faster through fast physical layer transmission, so as to quickly switch links, as described with reference to fig. 6 and 7, as shown in fig. 6, a 4-stage RRU is accessed from BBU optical port 1 to establish normal connection, and the cascade direction RRU1 to RRU4 is a forward link, when a link between RRU2 and RRU3 fails, RRU1 and RRU2 keep the original forward link unchanged, and RRU3 and RRU4 need to establish a reverse link with BBU optical port 2. As shown in fig. 7, the method for detecting a failure and switching a link according to the embodiment includes the following steps:

step S71, aiming at LOS/LOP fault, the optical module has a status indication, the FPGA can rapidly and accurately identify the fault by monitoring the status indication in real time, and aiming at the LOF fault, the FPGA analyzes frame synchronization information from a data packet according to an Ir interface protocol so as to acquire the LOF status, and can rapidly judge and detect due to high processing clock rate;

step S72, as shown in fig. 6, when an uplink fault is detected by the RUU2, the FPGA synthesizes the uplink fault information into a physical layer control word of the Ir interface protocol, and transmits the uplink fault information to the BBU via the RRU1, and when a downlink fault is detected by the RRU3, the FPGA synthesizes the downlink fault information into a physical layer control word of the Ir interface protocol, and transmits the downlink fault information to the RRU4, that is, the upper RRU at the fault transmits the uplink fault to the BBU step by step, and the lower RRU at the fault transmits the downlink fault to the rear RRU step by step;

step S73, after the main optical port of the BBU receives the fault information transmitted by the RRU through the uplink of the forward link, the main optical port of the BBU controls the auxiliary optical port to send the same service data as the service data sent to the RRU3 and the RRU4 from the auxiliary optical port of the BBU in the embodiment, which is the same as the service data sent to the RRU3 and the RRU4 from the main optical port before the fault, and then the service data sent to the RRU3 and the RRU4 from the original main optical port are deleted, after all RRUs in the fault rear stage receive the downlink fault information, the main and auxiliary optical ports of the RRU are switched, the pre-stored delay value and the IP address are correspondingly changed, the pre-stored antenna, cell and IQ data are configured unchanged, and the communication interaction is performed by reverse access from the auxiliary optical port of the BBU, so as to keep.

The invention provides a system for ring networking, which comprises:

the system comprises a baseband unit (BBU) and a plurality of radio frequency units (RRUs), wherein the BBU and the RRUs form an annular network in a cascading mode;

the RRU is accessed through one optical port of the BBU to establish a forward link, when the link fails, the optical port is switched, and the reverse link is configured by using the pre-stored parameters to continue providing services;

and the BBU provides baseband data to the RRUs through a certain optical interface, after acquiring the fault information of the link, the front-stage link of the fault point is maintained unchanged, the baseband data of the forward link of the rear stage of the fault point is deleted, the same baseband data is provided to each stage of RRUs of the reverse link from another optical interface, and the service is maintained.

A system configuration of an annular networking system provided in an embodiment of the present invention is shown in fig. 2, and includes an annular network topology structure formed by a BBU and a plurality of RRUs, where the RRUs are accessed from a main optical port in a forward direction, and when a link fails, service data is kept unchanged, and a link switching after the failure is performed; and the BBU provides a main optical interface data service for all the RRUs, and after a fault occurs, the service data which is the same as that of the main optical interface is provided for the auxiliary optical interface of the RRU at the rear stage of the fault. The functional structure of the BBU and RRU is explained below with reference to fig. 8.

As shown in fig. 8, the BBU according to the embodiment of the present invention includes the following 4 units:

a parameter generating unit U81, configured to establish service links with RRUs from two optical ports in advance, respectively, and generate configuration parameters related to the service of each level of RRU, where the configuration parameters include: different optical port IPs of the BBU, the IPs of each stage of RRU, uplink and downlink delay values, antennas, cells and IQ data;

the optical interface link establishing unit U82 is used for establishing a complete data service link with the RRU when the RRU is started out of order;

the fault acquisition unit U83 is used for receiving fault information transmitted by a forward link uplink from the RRU when a link fails to trigger the optical interface processing unit;

and the optical port processing unit U84 is used for performing optical port processing after receiving the trigger of the fault acquisition unit U83: and the auxiliary optical port reversely sends the service data of the original main optical port of the fault rear-stage RRU, deletes the service data sent to the fault rear-stage RRU by the main optical port, and adopts an auxiliary optical port IP to communicate with the fault rear-stage RRU.

As shown in fig. 8, the RRU according to the embodiment of the present invention includes the following 4 units:

the parameter storage unit U91 corresponds to the parameter generation unit U81, and is used for storing the parameters generated by U81 for the link switching unit U942;

a disorder link establishing unit U92, configured to establish a normal service data link with the BBU according to the disorder link establishing method described above;

the fault detection unit U93 is configured to complete fault detection on the link established by U92 according to the method described above, and send the result to the fault processing unit U94;

the failure processing unit U94 includes a failure transfer unit U941 and a link switching unit U942.

A fault transfer unit U941, configured to synthesize a result detected by U93 into a physical layer control word, and transfer the physical layer control word to an upper stage along a forward link and transfer the physical layer control word to a lower stage along the forward link;

and the link switching unit U942 is used for switching the main optical interface and the auxiliary optical interface of the link, replacing parameters in the U91, and establishing a reverse link with the BBU auxiliary optical interface.

In summary, the embodiments of the present invention provide a method and a system for link establishment and switching in an RRU ring network without changing hardware. However, the above embodiment is only one embodiment of the present invention, and the embodiment of the present invention is not limited by the above embodiment, and the spirit scope of the present invention is not limited by the above embodiment, and any other changes, modifications, substitutions, combinations, and simplifications which are made without departing from the principle of the present invention are included in the protection scope of the present invention.

Claims

1. A link switching method of RRU ring network is characterized in that: comprises the following steps of (1) carrying out the following steps,

the implementation of out-of-order starting of the RRU optical ports is as follows,

if the RRU is synchronous, the RRU sends broadcast access to the BBU, parameter configuration is carried out to complete link establishment, otherwise, if the auxiliary optical port has power, the storage optical port identification is modified, the RRU is reset, and if the auxiliary optical port has no power, the RRU is reset;

2. The link switching method of RRU ring networking according to claim 1, wherein: the RRU acquires and stores configuration parameters of two optical ports, and the implementation mode is,

3. The link switching method for RRU ring networking according to claim 2, wherein: the configuration parameters include the IP address and uplink and downlink delay values of the RRU corresponding to the optical port 1, the IP address and uplink and downlink delay values of the RRU corresponding to the optical port 2, and the antenna, the cell, and the IQ data after the normal access to the main optical port.

4. The link switching method for RRU ring networking according to claim 2, wherein: and the RRU adopts different IP addresses corresponding to different optical ports to realize a double-IP mechanism of the RRU optical ports.

5. The link switching method of the RRU ring network according to claim 1, 2, 3 or 4, wherein: the RRU link failure detection is implemented as follows,

6. The link switching method of the RRU ring network according to claim 1, 2, 3 or 4, wherein: the RRU link failure information transfer is implemented as follows,

7. The link switching method of the RRU ring network according to claim 2, 3 or 4, wherein: the manner of switching after RRU link failure is as follows,

8. An RRU ring network system, its characterized in that: the RRU is accessed from a main optical port in the forward direction, and when a link fails, service data is kept unchanged, and switching of a fault post-stage link is performed; the BBU provides a main optical port data service for all the RRUs, and after a fault occurs, service data which are the same as those of the main optical port are provided for an auxiliary optical port of a fault rear-stage RRU;

the BBU comprises the following units,

9. The RRU ring networking system of claim 8, wherein: the RRU comprises the following elements,

the RRU link failure detection is implemented as follows,

the RRU comprises an optical module, the optical module has a status indication for LOS/LOP fault, the FPGA acquires the fault by monitoring the status indication in real time, and for the LOF fault, the FPGA analyzes frame synchronization information from a data packet according to an Ir interface protocol so as to acquire the LOF status and inform a processor of the LOF status for processing;

the fault processing unit is used for transmitting fault information on a link according to a RRU fault transmission method and switching the link according to a method for switching after RRU link fault so as to keep continuous service;

the RRU link failure information transfer is implemented as follows,

when a front-stage RRU of a fault point detects an uplink fault, the FPGA synthesizes uplink fault information into a physical layer control word of an Ir interface protocol, the uplink fault information is transmitted to a BBU through all the front-stage RRUs in an uplink mode, a rear-stage RRU of the fault point detects a downlink fault, the FPGA synthesizes downlink fault information into a physical layer control word of the Ir interface protocol, and the downlink fault information is transmitted to the rear-stage RRU in a downlink mode;

the manner of switching after RRU link failure is as follows,

10. The RRU ring networking system of claim 9, wherein: the described fault detection unit comprises the following units,

the fault transfer unit is used for synthesizing the detection result of the fault detection unit into a physical layer control word, and transmitting the physical layer control word to a superior level along a forward link and transmitting the physical layer control word to a subordinate level along the forward link;