Patent Description:
Many radio networks use a distributed base station architecture, where a remote radio unit (Remote Radio Unit, RRU) is connected to a baseband processing unit (Baseband Control Unit, BBU) by an optical fiber, and one BBU can support multiple RRUs. In a scenario in which multiple RRUs need to be connected to a same BBU at a same station, cascading of the multiple RRUs is a common networking manner.

In the following, a data transmission mode of a wireless communications system <NUM> in which one BBU supports two cascaded RRUs is used as an example for description. As shown in <FIG>, in a downlink direction, a BBU <NUM> receives downlink data sent by a gateway, processes the downlink data, and sends processed downlink data to an optical transceiver (optical transceiver) <NUM> through a common public radio interface (Common Public Radio Interface, CPRI), where the optical transceiver is also referred to as an optical module. The optical transceiver <NUM> converts the processed downlink data into a first downlink optical carrier signal, and sends, through an optical fiber, the first downlink optical carrier signal to an optical transceiver <NUM> that corresponds to an RRU <NUM>; the optical transceiver <NUM> converts the first downlink optical carrier signal into a first downlink electrical signal, and sends the first downlink electrical signal to the RRU <NUM>; the RRU <NUM> selectively receives part of the first downlink electrical signal, sends the remaining signal to an optical transceiver <NUM>; the optical transceiver <NUM> converts the remaining signal into a second downlink optical carrier signal, and sends the second downlink optical carrier signal to an optical transceiver <NUM> through an optical fiber; the optical transceiver <NUM> converts the second downlink optical carrier signal into a second downlink electrical signal, and sends the second downlink electrical signal to an RRU <NUM>. In this way, the downlink data received from the gateway can be sent to a mobile terminal by using the RRU <NUM> and the RRU <NUM>.

In an uplink direction, the RRU <NUM> and the RRU <NUM> separately receive uplink data sent by the mobile terminal, and process the uplink data to obtain an uplink electrical signal. The RRU <NUM> sends an obtained first uplink electrical signal to the optical transceiver <NUM> that corresponds to the RRU <NUM>; the optical transceiver <NUM> converts the first uplink electrical signal into a first uplink optical carrier signal, and sends, through an optical fiber, the first uplink optical carrier signal to the optical transceiver <NUM> that corresponds to the RRU <NUM>; the optical transceiver <NUM> converts the first uplink optical carrier signal into a second uplink electrical signal, and sends the second uplink electrical signal to the RRU <NUM>; the RRU <NUM> integrates the second uplink electrical signal with the uplink electrical signal obtained by the RRU <NUM> to obtain a third uplink electrical signal, and sends the third uplink electrical signal to the optical transceiver <NUM> connected to the RRU <NUM>; the optical transceiver <NUM> converts the third uplink electrical signal into a second uplink optical carrier signal, and sends the second uplink optical carrier signal to the BBU <NUM> through an optical fiber, so that the BBU <NUM> processes the second uplink optical carrier signal and sends a processed second uplink optical carrier signal to the gateway.

It can be seen that the RRU <NUM> needs to forward data sent to or from the RRU <NUM>, and when the RRU <NUM> is faulty, the RRU <NUM> cannot work.

Therefore, the existing networking structure of a distributed base station has the following disadvantages: when an RRU (referred to as a current RRU) of cascaded RRUs is faulty, a next RRU cannot work, which reduces system reliability. The article "<NPL>" a dynamically allocating radio capacity technique.

The article "<NPL>, discloses cloud-radio-over-fiber (cloud-RoF) access network architecture.

<CIT> discloses a system for converting optical signals to MWOF signals for transmission to wireless data, audio and/or video terminals in the W-band. A centralized station performs the complex processing. In the system, a wavelength multiplexed signal is transmitted through a fiber. Optical filters selectively allow certain channels to be received by the respective remote stations. The optical filters can be a splitter and the optical filters pass the desired wavelengths at each remote station. The number of splitters and remote stations is greater than <NUM>.

The present invention is defined in the appended independent claim.

In view of this, embodiments of the present invention provide a wireless communications system and a wireless radio frequency apparatus, which resolve a technical problem of low system reliability caused by that when an RRU of multiple cascaded RRU is faulty in an existing distributed base station architecture, a next RRU cannot work.

In the wireless communications system of this application, optical signals of different RRUs are transmitted by using different wavelengths (which includes transmission from an RRU to a BBU, and transmission from a BBU to an RRU), and correspondingly, optical transceivers of the cascaded RRUs work at different wavelengths. Further, an optical splitter is further provided, and the optical transceivers of these cascaded RRUs are all connected to the optical splitter, and are connected to a same optical fiber by the optical splitter. In this way, optical signals of multiple RRUs that are transmitted on the optical fiber can be transmitted to the optical transceivers of all the RRUs by using the optical splitter, and each optical transceiver receives only a signal corresponding to its own operating wavelength; therefore, each RRU can correctly receive its own signal, and when an RRU is faulty, operation of the other RRUs is not affected, which greatly increases system reliability, and resolves the technical problem of low system reliability caused by that when a remote radio unit of multiple cascaded remote radio units is faulty in an existing distributed base station architecture, all next RRUs cannot work.

In addition, after the foregoing solution is used, each RRU receives its own signal without the need to forward a signal of another RRU, which reduces a requirement on bandwidth of a CPRI interface and reduces costs, and does not cause any limitation to a quantity of levels of cascaded RRUs. Further, each RRU no longer needs to be provided with two CPRI interfaces, thereby further reducing the costs. In addition, a decrease in the requirement on the bandwidth of the CPRI interface further reduces a requirement on a rate of an optical transceiver, which further reduces the costs.

To describe the technical solutions in the embodiments of the present invention or in the prior art more clearly, the following briefly introduces the accompanying drawings required for describing the embodiments. Apparently, the accompanying drawings in the following description show merely some embodiments of the present invention.

At present, in a distributed base station architecture, cascading of multiple RRUs is a common networking manner; however, for this networking manner, a current RRU sends data to a next RRU in a forwarding manner, and when the current RRU is faulty, all next RRUs cannot work, which results in reduced system reliability.

In this application, based on a full consideration of this problem, optical signals of different RRUs are transmitted by using different wavelengths (which includes transmission from an RRU to a BBU, and transmission from a BBU to an RRU), and correspondingly, optical transceivers of the cascaded RRUs work at different wavelengths. Further, an optical splitter is further provided, and the optical transceivers of these cascaded RRUs are all connected to the optical splitter, and are connected to a same optical fiber by the optical splitter. In this way, optical signals of multiple RRUs that are transmitted on the optical fiber can be transmitted to the optical transceivers of all the RRUs by using the optical splitter, and each optical transceiver receives only a signal corresponding to its own operating wavelength; therefore, each RRU can correctly receive its own signal, and when an RRU is faulty, working of the other RRUs is not affected, which greatly increases system reliability.

In addition, in the prior art, data of all RRUs needs to pass through a CPRI interface of the first RRU, and therefore, there is a relatively high requirement on bandwidth of the CPRI interface, which increases costs; and in a case in which the bandwidth of the CPRI interface is limited, a quantity of levels of cascaded RRUs is limited. In addition, an increase in the bandwidth of the CPRI interface increases a requirement on a rate of an optical transceiver, which further increases the costs.

However, after the foregoing solution is used, each RRU receives its own signal without the need to forward a signal of another RRU, which reduces the requirement on the bandwidth of the CPRI interface and reduces the costs, and does not cause any limitation to the quantity of levels of cascaded RRUs. Further, each RRU no longer needs to be provided with two CPRI interfaces, thereby further reducing the costs. In addition, a decrease in the requirement on the bandwidth of the CPRI interface further reduces the requirement on the rate of the optical transceiver, which further reduces the costs.

It can been seen that the technical solution of this application not only resolves the problem of low reliability in the prior art, but also greatly reduces costs, and does not cause any limitation to a quantity of levels of cascaded RRUs.

To make persons skilled in the art better understand the solution of the present invention, the following clearly and completely describes the technical solution in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely some rather than all of the embodiments of the present invention.

<FIG> is a schematic structural diagram of a wireless communications system <NUM> according to an embodiment of the present invention. As shown in <FIG>, the wireless communications system <NUM> includes: a baseband processing unit <NUM>, an optical multiplexer <NUM>, optical transceivers <NUM> and <NUM>, and a wireless radio frequency apparatus <NUM>, where the wireless radio frequency apparatus <NUM> includes remote radio units <NUM> and <NUM>, optical transceivers <NUM> and <NUM>, and an optical splitter <NUM>.

The baseband processing unit <NUM> is referred to as a BBU for short, with a full name being Baseband Control Unit, and is also referred to as a baseband control unit. The BBU <NUM> may include a transmission subsystem, a baseband subsystem, a control subsystem, and a power supply module. The transmission subsystem is configured to implement a function of transmitting and receiving data, and includes an interface between the BBU and a core network/controller and an interface between the BBU and a radio frequency module, where the interface between the BBU and the radio frequency module may be a common public radio interface (Common Public Radio Interface, CPRI) interface or an OBSAI (Open Base Station Architecture Initiative) interface. In this implementation manner, the BBU <NUM> includes two interfaces, that is, a quantity of interfaces is the same as a quantity of remote radio units <NUM>. The power supply module is configured to provide required power supply for the BBU <NUM>.

The baseband subsystem is mainly configured to implement a baseband processing function for uplink and downlink data, and mainly includes an uplink processing module and a downlink processing module. The uplink processing module is configured to demodulate and decode uplink baseband data from the transmission subsystem, and transmit decoded and demodulated data through the transmission subsystem; the downlink processing module is configured to modulate and encode downlink baseband data from the transmission subsystem, and transmit modulated and encoded data through the transmission subsystem.

The control subsystem is configured to manage the entire wireless communications system <NUM>, and the control subsystem may have, for example, one or more of the following functions: operation and maintenance functions such as device management, configuration management, alarm management, software management, and debugging and testing management; a signaling processing function such as logical resource management; clock module functions such as phase locking a GPS clock, performing frequency dividing, phase locking and phase adjustment, and providing a clock, which meets a requirement, for an entire base station.

The remote radio unit is referred to as a RRU for short, with a full name being Radio Remote Unit. The RRU is configured to send, to an antenna feeder and by means of transmission filtering, a downlink baseband signal that is received from the BBU <NUM> and has undergone frequency conversion, filtering, radio frequency filtering, and passed a linear power amplifier, or perform filtering, low noise amplification, further radio frequency small signal amplification and filtering, down-conversion, analog-to-digital conversion, digital intermediate frequency processing, and the like on an uplink signal received from a mobile terminal. Each RRU is communicatively connected to the BBU <NUM> by using one interface.

The optical multiplexer <NUM> is referred to as an optical MUX for short, with a full name being optical multiplexer. The optical multiplexer <NUM> is a device that combines and separates several optical carrier signals having different wavelengths, and may combine several optical carrier signals having different wavelengths onto one optical fiber for transmission, or separate optical carrier signals into multiple optical carrier signals according to the wavelengths to transmit the multiple optical carrier signals through multiple optical fibers. The optical multiplexer <NUM> generally includes multiple input interfaces and one output interface. In this implementation manner, the optical multiplexer <NUM> includes two input interfaces and one output interface, where both the input interfaces and the output interface are single-core bidirectional interfaces. In another implementation manner, the interfaces may be dual-core bidirectional interfaces.

The optical transceiver whose full name in English is optical transceiver is also referred to as an optical module, and is configured to implement optical/electrical conversion, where the optical/electrical conversion mentioned herein includes conversion from an optical signal to an electrical signal, and also includes conversion from an electrical signal to an optical signal. The optical transceivers <NUM> and <NUM> are provided between the BBU <NUM> and the optical multiplexer <NUM>, where the optical transceiver <NUM> is connected to one input interface of the optical multiplexer <NUM> and one CPRI interface of the BBU <NUM>, and the optical transceiver <NUM> is connected to another input interface of the optical multiplexer <NUM> and another CPRI interface of the BBU <NUM>. The optical transceivers <NUM> and <NUM> are connected to the RRUs <NUM> and <NUM>, respectively, that is, the optical transceiver <NUM> is connected to the RRU <NUM>, and the optical transceiver <NUM> is connected to the RRU <NUM>.

An optical transceiver generally includes an optoelectronic device, a functional circuit, an optical interface, and the like, where the optoelectronic device includes an emitting part and a receiving part. The emitting part is implemented as follows: after an electrical signal with a particular bit rate is input and processed by an internal driver chip, a semiconductor laser device (LD) or a light-emitting diode (LED) is driven to emit a modulated optical signal having a corresponding rate, where an automatic optical power control circuit is provided inside the optoelectronic device, so as to keep power of the output optical signal steady. The receiving part is implemented as follows: after an optical signal with a particular bit rate is input into the module, the optical signal is converted into an electrical signal by a photodetection diode; and a head amplifier amplifies the electrical signal and outputs an electrical signal with a corresponding bit rate. In short, a function of the optical transceiver is optical/electrical conversion.

Each optical transceiver connected to the BBU <NUM> is corresponding to one RRU, and at each RRU, one optical transceiver corresponding to the RRU is provided. Operating wavelengths of optical transceivers corresponding to a same RRU match each other, and operating wavelengths of optical transceivers corresponding to different RRUs are different, for example, operating wavelengths of the optical transceivers <NUM> and <NUM> corresponding to the RRU <NUM> match each other, and operating wavelengths of the optical transceivers <NUM> and <NUM> corresponding to the RRU <NUM> match each other, but the operating wavelengths of the optical transceivers <NUM> and <NUM> are different, and the operating wavelengths of the optical transceivers <NUM> and <NUM> are different, thereby ensuring that the optical transceiver corresponding to each RRU receives only a signal corresponding to its own operating wavelength. That operating wavelengths match each other mentioned herein refers to that a transmit wavelength of one optical transceiver is the same as a receive wavelength of another optical transceiver, so that the another optical transceiver can receive an optical signal sent by the optical transceiver. For example, a transmit wavelength of the optical transceiver <NUM> is equal to a receive wavelength of the optical transceiver <NUM>; and a receive wavelength of the optical transceiver <NUM> is equal to a transmit wavelength of the optical transceiver <NUM>. A transmit wavelength of the optical transceiver <NUM> is equal to a receive wavelength of the optical transceiver <NUM>; and a receive wavelength of the optical transceiver <NUM> is equal to a transmit wavelength of the optical transceiver <NUM>.

In addition, the foregoing optical transceivers may be dual-core bidirectional optical transceivers, or may be single-core bidirectional optical transceivers. When the optical transceivers are dual-core bidirectional optical transceivers, each optical transceiver has one operating wavelength, which is not only used for transmission, but also used for reception; when the optical transceivers are single-core bidirectional optical transceivers, each optical transceiver has two operating wavelengths, including a transmit wavelength and a receive wavelength. In this implementation manner, by way of example, the optical transceivers are single-core bidirectional optical transceivers, that is, transmission and reception are combined to be performed on one optical fiber, where different wavelengths are used to transmit and receive optical signals.

For example, the transmit wavelength of the optical transceiver <NUM> is λ1, and the receive wavelength of the optical transceiver <NUM> is λ2, where λ2 is unequal to λ1. The transmit wavelength of the optical transceiver <NUM> is λ3, and the receive wavelength of the optical transceiver <NUM> is λ4, where λ4 is unequal to λ3. Further, the transmit wavelength λ1 of the optical transceiver <NUM> is different from the transmit wavelength λ3 of the optical transceiver <NUM>, and the receive wavelength λ2 of the optical transceiver <NUM> is different from the receive wavelength λ4 of the optical transceiver <NUM>, so as to ensure that optical signals sent out by different optical transceivers can be received by different RRUs. In addition, because the foregoing optical transceivers are single-core bidirectional optical transceivers, the transmit wavelength λ1 and the receive wavelength λ2 of the optical transceiver <NUM> are different, and the transmit wavelength λ3 and the receive wavelength λ4 of the optical transceiver <NUM> are different; therefore, λ1, λ2, λ3, and λ4 are different from each other.

The optical transceiver <NUM> and the optical transceiver <NUM> are used in a paired manner, and the optical transceiver <NUM> and the optical transceiver <NUM> are used in a paired manner; therefore, when the transmit wavelength of the optical transceiver <NUM> is λ1, and the receive wavelength of the optical transceiver <NUM> is λ2, the receive wavelength of the optical transceiver <NUM> is λ1, and the transmit wavelength of the optical transceiver <NUM> is λ2; when the transmit wavelength of the optical transceiver <NUM> is λ3, and the receive wavelength of the optical transceiver <NUM> is λ4, the receive wavelength of the optical transceiver <NUM> is λ3, and the transmit wavelength of the optical transceiver <NUM> is λ4, where λ1, λ2, λ3, and λ4 are different from each other.

The optical transceivers <NUM> and <NUM> are connected, by the optical splitter <NUM>, to an optical fiber <NUM> that is connected to the optical multiplexer <NUM>. Specifically, the optical transceivers <NUM> and <NUM> may be connected to the optical splitter <NUM> by using an optical fiber, for example, a single-core bidirectional optical fiber. The optical multiplexer <NUM> may be also connected to the optical splitter <NUM> by using an optical fiber, for example, a single-core bidirectional optical fiber. Compared with using a dual-core bidirectional optical fiber, using the single-core bidirectional optical fiber reduces costs.

The optical splitter <NUM> is also referred to as an optical splitting device, is one of important passive devices on an optical fiber link, and is configured to perform coupling, splitting, and distribution of an optical signal. Quantities of input and output interfaces of the optical splitter <NUM> may be selected according to a need. As shown in <FIG>, in this implementation manner, a quantity of RRUs is two, a quantity of optical splitters <NUM> is one, and a quantity of optical multiplexers <NUM> is one, and in this case, the optical splitter <NUM> is a <NUM>:<NUM> optical splitter. Alternatively, as shown in <FIG> or <FIG>, when multiple RRUs are connected in a cascaded manner, that is, each RRU is connected to the optical splitter <NUM> by one optical transceiver, and the optical splitter <NUM> is also a <NUM>:<NUM> optical splitter. Because the <NUM>:<NUM> optical splitter has a small volume and can be directly placed in a maintenance cavity of the RRU, costs of mounting are reduced.

In this implementation manner, the quantity of RRUs is two, a quantity of interfaces of BBUs <NUM> is also two, a quantity of optical transceivers connected to the BBUs <NUM> is also two, and one optical transceiver is provided between each RRU and the optical splitter. In a specific implementation manner, the BBU <NUM> and the optical multiplexer <NUM> may be placed in an equipment room, and the RRUs <NUM> and <NUM> may be remotely placed at an outdoor station by using an optical fiber. The optical transceiver <NUM> is mounted on an interface <NUM>, corresponding to the RRU <NUM>, of the BBU <NUM>, and the optical transceiver <NUM> is mounted on an interface <NUM>, corresponding to the RRU <NUM>, of the BBU <NUM>. The optical transceiver <NUM> is mounted on the RRU <NUM>, and the optical transceiver <NUM> is mounted on the RRU <NUM>. The optical splitter <NUM> may be independently provided, or may be provided in a maintenance cavity of the RRU <NUM>.

In a downlink direction, the BBU <NUM> modulates and encodes downlink baseband data, and sends modulated and encoded downlink data to the optical transceivers <NUM> and <NUM> through the interface <NUM> and the interface <NUM>; the optical transceivers <NUM> and <NUM> convert the received downlink data into optical carrier signals having different wavelengths, and send the optical carrier signals to the optical multiplexer <NUM>; and the optical multiplexer <NUM> combines the optical carrier signals from the optical transceivers <NUM> and <NUM> onto one optical fiber, so as to send the optical carrier signals to the optical splitter <NUM> though the optical fiber. The optical transceivers <NUM> and <NUM> connected to the optical splitter <NUM> selectively receive, according to the wavelengths, data corresponding to the wavelengths. The receive wavelength of the optical transceiver <NUM> is equal to the transmit wavelength of the optical transceiver <NUM>, and the optical transceiver <NUM> can receive only data sent by the optical transceiver <NUM> to the optical multiplexer <NUM>; the receive wavelength of the optical transceiver <NUM> is equal to the transmit wavelength of the optical transceiver <NUM>, and the optical transceiver <NUM> can receive only data sent by the optical transceiver <NUM> to the optical multiplexer <NUM>. After converting received signals into downlink electrical signals, the two optical transceivers <NUM> and <NUM> send the downlink electrical signals to the RRUs <NUM> and <NUM>, respectively; and the RRUs <NUM> and <NUM> transmit the received signals to an antenna feeder by means of transmission filtering after the received signals undergoes radio frequency filtering and passes a linear power amplifier.

In an uplink direction, the RRUs <NUM> and <NUM> perform filtering, low noise amplification, further radio frequency small signal amplification and filtering, down-conversion, analog-to-digital conversion, digital intermediate frequency processing, and the like on an uplink signal received from a mobile terminal to generate uplink electrical signals, and transmit the uplink electrical signals to the optical transceivers <NUM> and <NUM>, respectively; and the optical transceivers <NUM> and <NUM> convert the received uplink electrical signals into uplink optical carrier signals. The optical transceivers <NUM> and <NUM> have different transmit wavelengths, where a transmit wavelength of the optical transceiver <NUM> is equal to the receive wavelength of the optical transceiver <NUM>, so that data sent by the optical transceiver <NUM> can be only received by the optical transceiver <NUM>; and a transmit wavelength of the optical transceiver <NUM> is equal to the receive wavelength of the optical transceiver <NUM>, so that data sent by the optical transceiver <NUM> can be only received by the optical transceiver <NUM>. The optical splitter <NUM> couples the received two links of uplink optical carrier signals onto a same downlink optical fiber, and sends the signals to the optical multiplexer <NUM>; the optical multiplexer <NUM> separates the received optical carrier signals, and separately sends the separated optical carrier signals to the optical transceivers <NUM> and <NUM>; the optical transceivers <NUM> and <NUM> convert the received optical carrier signals into uplink data signals, and send the uplink data signals to corresponding interfaces of the BBU <NUM>; and the BBU <NUM> demodulates and decodes the received uplink data signals, and transmits demodulated and decoded uplink data signals to a gateway.

It can be seen that when the RRU <NUM> is faulty, a signal of the RRU <NUM> can be directly transmitted to the optical splitter <NUM>, and transferred to the BBU <NUM> by using the optical splitter <NUM>, and a signal of the BBU <NUM> can also be transmitted to the RRU <NUM> by using the optical splitter <NUM>, thereby ensuring that the RRU <NUM> can work normally.

In the foregoing wireless communications system <NUM>, an optical splitter <NUM> is provided between two RRUs, that is, a first RRU <NUM> and a second RRU <NUM>, and even when the first RRU <NUM> is faulty, a signal of the second RRU <NUM> can be directly transmitted to the optical splitter <NUM>, and transferred to a BBU <NUM> by using the optical splitter <NUM>; and a signal of the BBU <NUM> can also be transmitted to the second RRU <NUM> by using the optical splitter <NUM>, thereby ensuring that the RRU <NUM> can work normally, which resolves a technical problem of low system reliability caused by that when a remote radio unit of multiple cascaded RRUs is faulty in an existing distributed base station architecture, all next RRUs cannot work.

In addition, all links use different wavelengths for communication, and are completely independent of each other, which also resolves a technical problem that when multiple RRUs are cascaded, a rate of an optical transceiver increases and a quantity of cascaded RRUs on a same link is limited because communication bandwidth is superimposed.

Base on a same inventive idea, this application further provides a wireless communications system <NUM>. As shown in <FIG>, the wireless communications system <NUM> is different from the wireless communications system <NUM> in that: a quantity of optical transceivers and a quantity of RRUs are different, and an optical splitter is different.

In this implementation manner, a quantity of RRUs <NUM> is M, correspondingly, M optical transceivers <NUM> are separately connected to the M RRUs <NUM>, and M optical transceivers <NUM> are provided on M interfaces between a BBU <NUM> and the M RRUs <NUM>. An optical splitter <NUM> may be a <NUM>:N optical splitter, where M is an integer greater than or equal to <NUM>, and N is an integer greater than or equal to <NUM>. The M RRUs <NUM> are separately connected to the optical splitter <NUM> by the M optical transceivers <NUM>.

In this implementation manner, N is equal to M, the optical splitter <NUM> is a <NUM>:M optical splitter and has M+<NUM> interfaces, where a quantity of optical splitters is one. In this case, all the RRUs <NUM> are connected the optical splitter <NUM>.

In another implementation manner, N may be unequal to M, for example, when N is equal to <NUM>, the optical splitter <NUM> is a <NUM>:<NUM> optical splitter and has three interfaces, where a quantity of optical splitters is M-<NUM>. One interface of a first optical splitter is connected to an optical multiplexer <NUM> by an optical fiber, so as to receive multiple links of optical signals that are obtained by the optical multiplexer <NUM> by means of combining, and the other two interfaces are separately connected to the first RRU <NUM> and the second optical splitter; one interface of the ith optical splitter is connected to the (i-<NUM>)th optical splitter, and the other two interfaces are separately connected to the ith RRU and the (i+<NUM>)th optical splitter, where <NUM>≤i≤M-<NUM>; one interface of the last optical splitter, that is, the (M-<NUM>)th optical splitter, is connected to the (M-<NUM>)th optical splitter, and the other two interfaces are separately connected to the (M-<NUM>)th RRU and the Mth RRU.

The operating principle of the foregoing wireless communications system <NUM> is the same as that of the wireless communications system <NUM>, and the details are not described herein again. When any RRU of the M RRUs <NUM> is faulty, signals of the other RRUs can be directly transmitted to the optical splitter <NUM>, and transferred to the BBU <NUM> by using the optical splitter <NUM>, and a signal of the BBU <NUM> can also be transmitted to the other RRUs <NUM> by using the optical splitter <NUM>, thereby ensuring that the other RRUs <NUM> can work normally, which resolves a technical problem of low system reliability caused by that when an RRU of multiple cascaded RRUs is faulty in an existing distributed base station architecture, all next RRUs cannot work.

Base on a same inventive idea, this application further provides a wireless communications system <NUM>. As shown in <FIG> is a schematic structural diagram of a wireless communications system <NUM> according to another embodiment of the present invention. The wireless communications system <NUM> is different from the wireless communications system <NUM> in <FIG> in that: a quantity of optical splitters <NUM> is two, and a quantity of RRUs <NUM> is three, and correspondingly, a quantity of interfaces of a BBU <NUM> is also three, a quantity of optical transceivers <NUM> connected to the BBU <NUM> is three, and a quantity of optical transceivers <NUM> connected to the RRUs <NUM> is also three.

The quantity of optical splitters <NUM> is one less than the quantity of RRUs <NUM>, that is, there are two optical splitters <NUM>, which are optical transceivers <NUM> and <NUM>. The optical splitter <NUM> is connected to an optical multiplexer <NUM> and the optical splitter <NUM>, an RRU <NUM> is connected to the optical splitter <NUM> by an optical transceiver <NUM>, an RRU <NUM> is connected to the optical splitter <NUM> by an optical transceiver <NUM>, and an RRU <NUM> is connected to the optical splitter <NUM> by an optical transceiver <NUM>.

In a specific implementation manner, the BBU <NUM> and the optical multiplexer <NUM> are placed in an equipment room, and the three RRUs <NUM> may be remotely placed at an outdoor station by using an optical fiber. An optical transceiver <NUM> is mounted on an interface <NUM>, corresponding to the first RRU <NUM>, of the BBU <NUM>; an optical transceiver <NUM> is mounted on an interface <NUM>, corresponding to the second RRU <NUM>, of the BBU <NUM>; an optical transceiver <NUM> is mounted on an interface <NUM>, corresponding to the third RRU <NUM>, of the BBU <NUM>. The optical transceiver <NUM> is mounted on the RRU <NUM>, the optical transceiver <NUM> is mounted on the RRU <NUM>, and the optical transceiver <NUM> is mounted on the RRU <NUM>. The optical splitter <NUM> is placed in a maintenance cavity of the remote radio unit <NUM>, and the optical splitter <NUM> is placed in a maintenance cavity of the RRU <NUM>.

In a downlink direction, the BBU <NUM> modulates and encodes downlink baseband data, and sends modulated and encoded downlink data to the optical transceivers <NUM>, <NUM> and <NUM> through the interface <NUM>, the interface <NUM>, and the interface <NUM>; the optical transceivers <NUM>, <NUM> and <NUM> convert the received downlink data into optical carrier signals having different wavelengths, and send the optical carrier signals to the optical multiplexer <NUM>; and the optical multiplexer <NUM> combines the received optical carrier signals onto one optical fiber, and sends the optical carrier signals to the three optical transceivers <NUM> through the optical splitters <NUM>; and the three optical transceivers <NUM> selectively receive, according to the wavelengths, data corresponding to the wavelengths. A receive wavelength of the optical transceiver <NUM> is equal to a transmit wavelength of the optical transceiver <NUM>, and the optical transceiver <NUM> can receive only data sent by the optical transceiver <NUM>; a receive wavelength of the optical transceiver <NUM> is equal to a transmit wavelength of the optical transceiver <NUM>, and the optical transceiver <NUM> can receive only data sent by the optical transceiver <NUM>; a receive wavelength of the optical transceiver <NUM> is equal to a transmit wavelength of the optical transceiver <NUM>, and the optical transceiver <NUM> can receive only data sent by the optical transceiver <NUM>. After converting the received signals into downlink electrical signals, the three optical transceivers <NUM> send the downlink electrical signals to the three RRUs <NUM>, and the three RRUs <NUM> sends the received signals to an antenna feeder by means of transmission filtering after the signals undergoes radio frequency filtering and passes a linear power amplifier.

In an uplink direction, the three RRUs <NUM> perform filtering, low noise amplification, further radio frequency small signal amplification and filtering, down-conversion, analog-to-digital conversion, digital intermediate frequency processing, and the like on an uplink signal received from a mobile terminal to generate uplink electrical signals, and transmit the uplink electrical signals to the three optical transceivers <NUM>; and the three optical transceivers <NUM> convert the received uplink electrical signals into uplink optical carrier signals. The three optical transceivers <NUM> have different transmit wavelengths, where a transmit wavelength of the optical transceiver <NUM> is equal to a receive wavelength of the optical transceiver <NUM>, and data sent by the optical transceiver <NUM> can be only received by the optical transceiver <NUM>; a transmit wavelength of the optical transceiver <NUM> is equal to a receive wavelength of the optical transceiver <NUM>, and data sent by the optical transceiver <NUM> can be only received by the optical transceiver <NUM>; and a transmit wavelength of the optical transceiver <NUM> is equal to a receive wavelength of the optical transceiver <NUM>, and data sent by the optical transceiver <NUM> can be only received by the optical transceiver <NUM>. The optical splitters <NUM> and <NUM> couple the three links of uplink optical carrier signals onto a same downlink optical fiber, and send the signals to the optical multiplexer <NUM>; the optical multiplexer <NUM> separates the received optical carrier signals, and separately sends the separated optical carrier signals to the optical transceivers <NUM><NUM>, and <NUM>; after separately converting the received optical carrier signals into uplink data signals, the optical transceivers <NUM>, <NUM>, and <NUM> send the uplink data signals to the corresponding three interfaces <NUM>, <NUM>, and <NUM> of the BBU <NUM>, respectively; and the BBU <NUM> demodulates and decodes the received uplink data signals, and transmits demodulated and decoded uplink data signals to a gateway.

It can be seen that in the foregoing embodiment, optical signals of different RRUs are transmitted by using different wavelengths, and correspondingly, optical transceivers of the cascaded RRUs work at different wavelengths. Optical splitters are further provided, and the optical transceivers of these cascaded RRUs are all connected to the optical splitters, and are connected to a same optical fiber <NUM> by the optical splitters. In this way, the optical signals of the multiple RRUs that are transmitted on the optical fiber can be transmitted to the optical transceivers of all the RRUs by using the optical splitters, and each optical transceiver receives only a signal corresponding to its own operating wavelength; therefore, each RRU can correctly receive its own signal, and when an RRU is faulty, operation of the other RRUs is not affected. For example, when the RRU <NUM> is faulty, signals of the RRUs <NUM> and <NUM> can be directly transferred to the BBU <NUM> by using the optical splitter <NUM>, and a signal of the BBU <NUM> can also be transmitted to the RRU <NUM> and the RRU <NUM> by using the optical splitter <NUM>, thereby ensuring that the RRUs <NUM> and <NUM> can work normally. When both the RRU <NUM> and the RRU <NUM> are faulty, the RRU <NUM> can transfer a signal to the BBU <NUM> by using the optical splitters <NUM> and <NUM>, and a signal of the BBU <NUM> can also be transferred to the RRU <NUM> by using the optical splitters <NUM> and <NUM>, which resolves a technical problem of low system reliability caused by that when an RRU of multiple cascaded RRUs is faulty in an existing distributed base station architecture, all next RRUs cannot work.

Base on a same inventive idea, this application further provides a wireless communications system <NUM>. As shown in <FIG> is a schematic structural diagram of a wireless communications system <NUM> according to still another embodiment of the present invention. The wireless communications system <NUM> is different from the wireless communications system <NUM> in <FIG> in that: a quantity of RRUs <NUM>, a quantity of optical splitters <NUM>, and a quantity of optical transceivers <NUM> are different. In this implementation manner, the quantity of RRUs <NUM> is M, where M is greater than <NUM>; correspondingly, M optical transceivers <NUM> are separately connected to the M RRUs, and M optical transceivers <NUM> are provided on M interfaces between a BBU <NUM> and the M RRUs <NUM>. The optical splitter <NUM> is a <NUM>:<NUM> optical splitter, and the quantity of optical splitters <NUM> is M-<NUM>, where the M-<NUM> optical splitters <NUM> are cascaded by using a single-core optical fiber <NUM>.

One interface of the first optical splitter <NUM> is connected to an optical multiplexer <NUM> by the optical fiber <NUM>, so as to receive multiple links of optical signals that are obtained by the optical multiplexer <NUM> by means of combining, and the other two interfaces are separately connected to the first RRU <NUM> and the second optical splitter <NUM>; one interface of the ith optical splitter <NUM> is connected to the (i-<NUM>)th optical splitter <NUM>, and the other two interfaces are separately connected to the ith RRU and the (i+<NUM>)th optical splitter <NUM>, where <NUM>≤i≤M-<NUM>; one interface of the last optical splitter <NUM>, that is, the (M-<NUM>)th optical splitter <NUM>, is connected to the (M-<NUM>)th optical splitter <NUM>, and the other two interfaces are separately connected to the (M-<NUM>)th RRU <NUM> and the Mth RRU <NUM>.

In a specific implementation manner, the BBU <NUM> and the optical multiplexer <NUM> may be placed in an equipment room, and the M RRUs <NUM> may be remotely placed at an outdoor station by using an optical fiber. The first optical transceiver <NUM> is mounted on an interface <NUM>, corresponding to the first RRU <NUM>, of the BBU <NUM>; the jth optical transceiver <NUM> is mounted on an interface j, corresponding to the jth RRU, of the BBU <NUM>, where <NUM><j<M; the Mth optical transceiver <NUM> is mounted on an interface M, corresponding to the Mth RRU <NUM>, of the BBU <NUM>. The first optical transceiver <NUM> is mounted on the first RRU <NUM>, the jth optical transceiver is mounted on the jth RRU <NUM>, where <NUM><j<M, and the Mth optical transceiver <NUM> is mounted on the Mth RRU <NUM>. In addition, the first optical splitter <NUM> may be placed in a maintenance cavity of the first RRU <NUM>, the ith optical splitter <NUM> may be placed in a maintenance cavity of the ith RRU <NUM>, where <NUM>≤i≤M-<NUM>, and the (M-<NUM>)th optical splitter <NUM> may be placed in a maintenance cavity of the (M-<NUM>)th RRU <NUM>. However, this embodiment is not limited thereto, and the optical splitters <NUM> may be placed independently, or placed in another manner.

In a downlink direction, the BBU <NUM> modulates and encodes downlink baseband data, and sends modulated and encoded downlink data to the M optical transceivers <NUM>; the M optical transceivers <NUM> convert the received downlink data into optical carrier signals having different wavelengths, and send the optical carrier signals to the optical multiplexer <NUM>; the optical multiplexer <NUM> combines the received optical carrier signals onto one optical fiber, and sends the optical carrier signals to the M optical transceivers <NUM> through the optical splitters <NUM>; and the M optical transceivers <NUM> selectively receive, according to the wavelengths, data sent to the M optical transceivers. After separately converting the received signals into downlink electrical signals, the M optical transceivers <NUM> send the downlink electrical signals to the M RRUs <NUM>; and the M RRUs <NUM> separately transmit the received signals to an antenna feeder by means of transmission filtering after the received signals undergoes radio frequency filtering and passes a linear power amplifier.

In an uplink direction, the M RRUs <NUM> perform filtering, low noise amplification, further radio frequency small signal amplification and filtering, down-conversion, analog-to-digital conversion, digital intermediate frequency processing, and the like on an uplink signal received from a mobile terminal to generate uplink electrical signals, and transmit the uplink electrical signals to the M optical transceivers <NUM> correspondingly; and the M optical transceivers <NUM> separately convert the received uplink electrical signals into uplink optical carrier signals and send the uplink optical carrier signals to the optical splitters <NUM>.

The M optical transceivers <NUM> have different transmit wavelengths. Each optical transceiver <NUM> has one optical transceiver <NUM> matching the optical transceiver <NUM>, that is, a transmit wavelength of each optical transceiver <NUM> is equal to a receive wavelength of one optical transceiver <NUM>, and data sent by the optical transceiver <NUM> can only be received by the optical transceiver. The optical splitters <NUM> couple M links of uplink optical carrier signals onto a same downlink optical fiber, and send the signals to the optical multiplexer <NUM>; the optical multiplexer <NUM> separates the received optical carrier signals, and sends the separated optical carrier signals separately to the M optical transceivers <NUM>; the M optical transceivers <NUM> convert the received optical carrier signals into uplink data signals, and send the uplink data signals to the BBU <NUM>; and the BBU <NUM> demodulates and decodes the received uplink data signals, and transmits demodulated and decoded uplink data signals to a gateway.

It can be seen that in the foregoing embodiment, optical signals of different RRUs are transmitted by using different wavelengths, and correspondingly, optical transceivers of the cascaded RRUs work at different wavelengths. Optical splitters are further provided, and the optical transceivers of these cascaded RRUs are all connected to the optical splitters, and are connected to a same optical fiber by the optical splitters. In this way, the optical signals of the multiple RRUs that are transmitted on the optical fiber can be transmitted to the optical transceivers of all the RRUs by using the optical splitters, and each optical transceiver receives only a signal corresponding to its own operating wavelength; therefore, each RRU can correctly receive its own signal, and when an RRU is faulty, operation of the other RRUs is not affected. For example, when the first RRU is faulty, signals of the other RRUs can be directly transferred to the BBU <NUM> by using the optical splitters <NUM>, and a signal of the BBU <NUM> can also be transmitted to the other RRUs by using the optical splitters <NUM>, thereby ensuring that the other RRUs can work normally, which resolves a technical problem of low system reliability caused by that when an RRU of multiple cascaded RRUs is faulty in an existing distributed base station architecture, all next RRUs cannot work.

Based on a same inventive idea, this application further provides a wireless radio frequency apparatus, where the wireless radio frequency apparatus includes:.

Preferably, the optical splitter is a <NUM>:N optical splitter, where N is an integer greater than or equal to <NUM> and less than or equal to M.

Preferably, the optical splitter is a <NUM>:<NUM> optical splitter, and a quantity of optical splitters is M-<NUM>.

Preferably, when M is greater than <NUM>, the M-<NUM> optical splitters are connected to each other by a single-core optical fiber.

Preferably, the optical fiber is a single-core optical fiber.

Preferably, an operating wavelength of each optical transceiver of the first optical transceivers and the second optical transceivers includes a receive wavelength and a transmit wavelength.

It can be seen that in the embodiment, optical signals of different RRUs are transmitted by using different wavelengths (which includes transmission from an RRU to a BBU, and transmission from a BBU to an RRU), and correspondingly, optical transceivers of the cascaded RRUs work at different wavelengths. Further, an optical splitter is further provided, and the optical transceivers of these cascaded RRUs are all connected to the optical splitter, and are connected to a same optical fiber by the optical splitter. In this way, optical signals of multiple RRUs that are transmitted on the optical fiber can be transmitted to the optical transceivers of all the RRUs by using the optical splitter, and each optical transceiver receives only a signal corresponding to its own operating wavelength; therefore, each RRU can correctly receive its own signal, and when an RRU is faulty, operation of the other RRUs is not affected, which greatly increases system reliability.

However, after the foregoing solution is used, each RRU receives its own signal without the need to forward a signal of another RRU, which reduces the requirement on the bandwidth of the CPRI and reduces the costs, and does not cause any limitation to the quantity of levels of cascaded RRUs. Further, each RRU no longer needs to be provided with two CPRI interfaces, thereby further reducing the costs. In addition, a decrease in the requirement on the bandwidth of the CPRI interface further reduces the requirement on the rate of the optical transceiver, which further reduces the costs.

Further embodiments of the present invention are provided in the following. It should be noted that the numbering used in the following section does not necessarily need to comply with the numbering used in the previous sections.

Embodiment <NUM>. A wireless radio frequency apparatus, wherein the wireless radio frequency apparatus comprises:.

Embodiment <NUM>. The apparatus according to embodiment <NUM>, wherein the optical splitter is a <NUM>:N optical splitter, and N is an integer greater than or equal to <NUM> and less than or equal to M.

Embodiment <NUM>. The apparatus according to embodiment <NUM>, wherein the optical splitter is a <NUM>:<NUM> optical splitter, and a quantity of optical splitters is M-<NUM>.

Embodiment <NUM>. The apparatus according to embodiment <NUM>, wherein when M is greater than <NUM>, the M-<NUM> optical splitters are connected to each other by a single-core optical fiber.

Embodiment <NUM>. The apparatus according to any one of embodiments <NUM> to <NUM>, wherein the optical fiber is a single-core optical fiber.

Embodiment <NUM>. The apparatus according to any one of embodiments <NUM> to <NUM>, wherein an operating wavelength of each optical transceiver of the first optical transceivers and the second optical transceivers comprises a receive wavelength and a transmit wavelength.

Embodiment <NUM>. A wireless communications system, wherein the wireless communications system comprises:.

Embodiment <NUM>. The wireless communications system according to embodiment <NUM>, wherein the optical splitter is a <NUM>:N optical splitter, and N is an integer greater than or equal to <NUM> and less than or equal to M.

Embodiment <NUM>. The wireless communications system according to embodiment <NUM>, wherein the optical splitter is a <NUM>:<NUM> optical splitter, and a quantity of optical splitters is M-<NUM>.

Embodiment <NUM>. The wireless communications system according to embodiment <NUM>, wherein when M is greater than <NUM>, the M-<NUM> optical splitters are connected to each other by a single-core optical fiber.

Embodiment <NUM>. The wireless communications system according to any one of embodiments <NUM> to <NUM>, wherein the optical fiber is a single-core optical fiber.

Embodiment <NUM>. The wireless communications system according to any one of embodiments <NUM> to <NUM>, wherein an operating wavelength of each optical transceiver of the first optical transceivers and the second optical transceivers comprises a receive wavelength and a transmit wavelength.

Embodiment <NUM>. The system according to embodiment <NUM>, wherein that an operating wavelength of a first optical transceiver matches an operating wavelength of a second optical transceiver corresponding to the first optical transceiver comprises that:
in the first optical transceiver and the second optical transceiver corresponding to the first optical transceiver, the transmit wavelength of the first optical transceiver is the same as the receive wavelength of the second optical transceiver; and the receive wavelength of the first optical transceiver is the same as the transmit wavelength of the second optical transceiver.

Although some preferred embodiments of the present invention have been described, persons skilled in the art can make changes and modifications to these embodiments once they learn the basic inventive concept. Therefore, the following claims are intended to be construed as to cover the preferred embodiments and all changes and modifications falling within the scope of the present invention.

Claim 1:
An apparatus, comprises M-<NUM> optical splitters (<NUM>) and M first optical transceivers (<NUM>), wherein M is an integer greater than or equal to <NUM>, and operating wavelengths of the M first optical transceivers (<NUM>) are different from each other, and the M-<NUM> optical splitters (<NUM>) are <NUM>:<NUM> optical splitters and have three interfaces, wherein:
one interface of a first optical splitter (<NUM>) is configured to receive multiple links of optical signals, and the other two interfaces are separately connected to the first optical transceiver (<NUM>) of the M first optical transceivers (<NUM>) and a second optical splitter (<NUM>);
one interface of the ith optical splitter (<NUM>) is connected to the (i-<NUM>)th optical splitter (<NUM>), and the other two interfaces are separately connected to the ith optical transceiver (<NUM>) of the M first optical transceivers (<NUM>) and the (i+<NUM>)th optical splitter (<NUM>), where <NUM>≤i≤M-<NUM>;
one interface of the (M-<NUM>)th optical splitter (<NUM>) is connected to the (M-<NUM>)th optical splitter (<NUM>), and the other two interfaces are separately connected to the (M-<NUM>)th optical transceiver (<NUM>) and the Mth optical transceiver (<NUM>) of the M first optical transceivers (<NUM>); and
the M first optical transceivers (<NUM>) are single-core bidirectional optical transceivers, and the operating wavelength of each first optical transceiver (<NUM>) comprises a transmit wavelength and a receive wavelength, which are different and are respectively used to transmit and receive optical signals.