WO2009003338A1 - Système d'accès radio à base de station de base centralisée et procédé à déplacement de fréquence - Google Patents

Système d'accès radio à base de station de base centralisée et procédé à déplacement de fréquence Download PDF

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Publication number
WO2009003338A1
WO2009003338A1 PCT/CN2007/003952 CN2007003952W WO2009003338A1 WO 2009003338 A1 WO2009003338 A1 WO 2009003338A1 CN 2007003952 W CN2007003952 W CN 2007003952W WO 2009003338 A1 WO2009003338 A1 WO 2009003338A1
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unit
optical
frequency
carrier frequency
wavelength
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PCT/CN2007/003952
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English (en)
Chinese (zh)
Inventor
Zhiyong Zhao
Baiqing Zong
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Zte Corporation
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Publication of WO2009003338A1 publication Critical patent/WO2009003338A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices
    • H04W88/085—Access point devices with remote components

Definitions

  • Wireless access system based on centralized base station and carrier frequency shifting method
  • the present invention relates to a wireless signal access technology in the field of wireless communication, and in particular to a wireless access system based on a centralized base station and a carrier frequency shifting method.
  • Wireless communication is one of the most active branches in the communications field and the fastest growing communication technology.
  • the concept of cellular has led to the rapid development of mobile communications.
  • Both the first-generation analog communication system, the second-generation digital communication system, and the third-generation communication have adopted the cellular coverage network structure.
  • Cellular coverage is to divide a geographical area into several cells.
  • Each base station establishes a base station and an antenna (there are also cases where several cells share one base station and antenna) to cover the entire cell, and all users in the small area access the base station.
  • This kind of network structure plays a certain role in improving the utilization rate of frequency borrowing.
  • the conventional method is to perform cell splitting and cell sectorization. However, this method can only alleviate the limited spectrum, system capacity and higher and higher to some extent.
  • the contradiction between the communication requirements, because cell splitting and sectorization can not proceed without limit, which will bring many problems such as interference, frequent switching and so on.
  • the distributed antenna system is a new wireless access network structure that separates the base station from the antenna, transmits the base station signal to the antenna using the optical fiber, and then transmits it to the user.
  • the system uses abundant optical fiber resources as an extension of wireless communication, and a large number of distributed antennas are closer to the user, and several antennas around the user form a cell centered on the end user, thus, the antenna and the terminal
  • the transmit power can be greatly reduced, and at the same time, the spectrum utilization and system capacity can be greatly improved.
  • the technical problem to be solved by the present invention is to provide a wireless access system based on a centralized base station and a carrier frequency shifting method, so as to realize a general shift of a virtual carrier frequency and a dynamic configuration of a wireless resource.
  • the present invention provides a wireless access system based on a centralized base station, including a centralized base station and a plurality of remote antenna units, which are connected by a fiber link; the centralized base station is used to The carrier frequency signal is modulated and multiplexed onto the optical wave, and the optical wave is multiplexed onto the optical fiber link;
  • the remote antenna unit is configured to demodulate the carrier frequency signal after receiving the optical wave from the optical fiber link, and transmit to the area covered by the transmitting antenna via the transmitting antenna.
  • the above-mentioned centralized base station-based wireless access system may further have the following features: the optical fiber link includes a wavelength division multiplexing all-fiber ring network, an optical add/drop multiplexer OADM node on the network, and the OADM from the OADM The fiber branch that the node picks up.
  • the above-mentioned centralized base station-based wireless access system may further have the following features: the remote antenna unit includes a fiber link interface unit, a radio frequency front end, and an antenna system; and the fiber link interface unit is used for a slave fiber chain
  • the carrier frequency signal modulated on the optical wave is downloaded to the remote antenna unit, and the uplink electrical signal received by the remote antenna unit is converted into an optical signal, and sent to the optical fiber link;
  • the radio frequency front end is configured to modulate a downlink baseband signal into a radio frequency signal, and downconvert the uplink radio frequency signal into a baseband signal;
  • the antenna system is configured to send the radio frequency signal and receive the radio frequency signal.
  • the above-described centralized base station-based radio access system may further have the following features: the centralized base station includes a baseband processing unit, a radio frequency cross-connect unit, a sub-carrier modulation unit, an optical cross-connect unit, a wavelength division multiplexing unit, and Control the maintenance unit, where:
  • the baseband processing unit is configured to perform baseband processing and partial radio frequency processing of all carrier frequency signals in a downlink direction, convert the carrier frequency signal into an analog intermediate frequency or radio frequency signal, and send the signal to the radio frequency cross-connect unit;
  • the radio frequency cross-connect unit is configured to complete, in a downlink direction, a routing function of an analog intermediate frequency or radio frequency signal outputted by the baseband processing unit to the subcarrier modulation unit;
  • the subcarrier modulation unit is configured to: in the downlink direction, generate a frequency modulation to form a modulated signal by using a frequency of the analog intermediate frequency or the radio frequency signal, multiplex the modulated signal onto one optical wave, and send the optical wave to the optical Cross-connect unit
  • the optical cross-connect unit is configured to route the optical wave to a corresponding wavelength division multiplexing unit in a downlink direction;
  • the wavelength division multiplexing unit is configured to multiplex the optical wave into a corresponding optical fiber link in a downlink direction;
  • the control and maintenance unit is configured to control and maintain the work of each unit.
  • the wireless access system based on the centralized base station may further have the following features: the control and maintenance unit controls and maintains the work of each unit in the system by using the saved information, where the saved information includes the following One or more:
  • Carrier frequency signal information which is the serial number of the carrier frequency signal
  • a sub-carrier modulation unit configured to modulate a frequency-shifted carrier frequency signal by using a modulation frequency / s according to the correspondence relationship, where is a sequence number of the modulation frequency;
  • Corresponding relationship information of the optical wavelength and the modulation frequency f sn wherein the subcarrier modulation unit is configured to multiplex the carrier frequency signal modulated by the modulation frequency f m to the corresponding wavelength wave according to the correspondence relationship, where Is the serial number of the wavelength of the light wave;
  • the optical cross-connecting unit is configured to output, according to the correspondence relationship, a light wave having a wavelength of the carrier frequency signal by optical cross-connection and outputting a wavelength of light according to the correspondence relationship, wherein For the wavelength of the light;
  • the wavelength division multiplexing unit is configured to multiplex the optical wave having the wavelength of 4 W into the corresponding m according to the correspondence relationship, ⁇ The serial number of a WDM unit;
  • the wavelength division multiplexing The element is configured to output the light wave in the unit to the corresponding fiber link h according to the corresponding relationship, where is a fiber link serial number;
  • the remote antenna unit identifies the ID information, including the element is the remote antenna unit ID number, and the remote antenna unit has a fixed connection relationship with the optical fiber link, that is, each remote antenna unit is connected to one optical fiber branch of the optical fiber link. .
  • the above-described centralized base station-based wireless access system may further have the following features: the baseband processing unit, the radio frequency cross-connect unit, the sub-carrier modulation unit, the optical cross-connect unit, the wavelength division multiplexing unit, and the control and maintenance unit are Reverse processing in the upstream direction is performed in the uplink direction.
  • the centralization base station-based radio access system may further have the following feature: the centralization base station further includes a frequency shift keying unit configured to detect carrier frequency information modulated by the subcarrier modulation unit And comparing the carrier frequency information with carrier frequency information modulated by the control maintenance unit control subcarrier modulation unit to verify the accuracy of the modulation process of the subcarrier modulation unit.
  • a frequency shift keying unit configured to detect carrier frequency information modulated by the subcarrier modulation unit And comparing the carrier frequency information with carrier frequency information modulated by the control maintenance unit control subcarrier modulation unit to verify the accuracy of the modulation process of the subcarrier modulation unit.
  • the above-mentioned centralized base station-based wireless access system may further have the following features: the optical network node distinguishes optical wave signals by a tunable OADM, and the remote antenna unit distinguishes and downloads wireless carriers of different frequencies through filters. Frequency signal.
  • the present invention also provides a carrier frequency shifting method based on the above wireless access system, comprising the following steps:
  • the centralized base station performs frequency shifting on the carrier frequency signal according to the corresponding relationship, then modulates and multiplexes the carrier frequency signal onto a corresponding one-way optical wave, and then sends the optical wave to the corresponding optical fiber link through the corresponding optical fiber link.
  • Remote antenna unit Further, the method for carrying the carrier frequency shift based on the centralized base station may further have the following features: after the step (2), the method further includes the following steps: the remote antenna unit extracts the carrier frequency signal from the optical wave, and It is transmitted via its upper transmitting antenna to the area it covers.
  • the carrier-based moving method based on the centralized base station may further have the following features:
  • the related information of the corresponding relationship includes one or more of the following information: Carrier frequency signal ⁇ information, N is the carrier frequency signal sequence number
  • the carrier frequency signal modulated by the modulation frequency is multiplexed onto the corresponding optical wave of the wavelength U, where is the serial number of the wavelength of the optical wave;
  • a correspondence relationship with the fiber link L k WDMi wavelength division multiplexing unit only the corresponding relationship according to the Gen subjects -the ⁇ wave to the output unit corresponding to the optical fiber link ⁇ , wherein an optical fiber link ID;? Away End antenna unit ID list, in which the element R p , ;? For the remote antenna unit ID number, the remote antenna unit has a fixed connection relationship with the fiber link, that is, each remote antenna unit is connected to one fiber branch in the fiber link.
  • the carrier-based moving method based on the centralized base station may further have the following features:
  • the mapping relationship table when the mapping relationship table is configured, one optical wave is avoided, and two or more of the same frequency are carried.
  • Wireless carrier signals or to avoid carrying two or more identical optical waves on a single fiber.
  • the proposed wireless access system based on the centralized base station inherits the advantages of the distributed antenna system, improves the frequency utilization and system capacity, and realizes the functions of virtual carrier frequency and dynamic allocation of wireless resources. .
  • the centralized base station concentrates all carrier frequency resources, and the baseband signal processing and most of the radio frequency processing are completed in the centralized base station.
  • the radio frequency cross connection unit, the subcarrier modulation unit, the optical cross connection unit, and the WDM unit complete the carrier frequency signal to the optical wave. Modulation, carrier frequency
  • the routing and optical routing functions enable dynamic configuration of carrier frequencies and adjustment of radio resources without changing the hardware of the centralized base station.
  • the RF cross-connect unit, the sub-carrier modulation unit, the optical cross-connect unit and the WDM unit complete the routing function of the carrier frequency signal to different remote antenna units, realizing the virtual carrier frequency shifting and the dynamic configuration of the radio resources, and capable of solving the burst Peak business needs for the network.
  • the wireless access system based on the centralized base station realizes the optimization of network resource configuration and reduces the equipment investment of operators. Due to the virtual carrier frequency shifting function, the carrier frequency of the entire network does not need to be configured according to the maximum traffic volume, but only needs to be configured according to the average traffic volume, thereby greatly saving investment. In addition, since the remote antenna unit device is greatly enlarged, the system robustness is enhanced, maintenance-free can be realized, and maintenance cost is saved. BRIEF abstract
  • FIG. 1 is a network structure diagram of a wireless access system based on a centralized base station according to an embodiment of the present invention
  • FIG. 2 is a schematic structural diagram of a logic module of a centralized base station according to an embodiment of the present invention
  • FIG. 3 is a schematic structural diagram of a remote antenna unit according to an embodiment of the present invention.
  • FIG. 4 is a structural diagram of a centralized base station system in an embodiment of the present invention.
  • FIG. 5 is a schematic diagram showing a general shift of a virtual carrier frequency of a centralized base station according to an embodiment of the present invention.
  • the wireless access system based on the centralized base station proposed by the invention inherits the advantages of the distributed antenna system, and realizes the functions of virtual carrier frequency shifting and dynamic configuration of wireless resources while improving spectrum utilization and system capacity.
  • the dynamics here means that the correspondence between the baseband and the radio can be changed as needed. This change is implemented by configuration.
  • the configuration process can be performed during the work of the base station or when there is no communication service.
  • the wireless access system based on the centralized base station only has one large-capacity centralized base station (CB) and several remote antenna units (RAUs) in the metropolitan area, and the two are connected through optical fibers.
  • CB central base station
  • RAUs remote antenna units
  • Centralized base station transmits intermediate frequency or radio frequency signals through optical fibers
  • DAN Distributed Antenna Network
  • the centralized base station concentrates all carrier frequency resources, and the baseband signal processing and most of the radio frequency processing are completed in the centralized base station.
  • the virtual carrier frequency is realized by the modulation of the carrier frequency signal to the optical wave, the carrier frequency signal routing and the optical wave routing function.
  • the dynamic configuration of moving and wireless resources solves the demand for network in the event of sudden peak traffic.
  • the wireless access system based on the centralized base station includes a centralized base station and a plurality of remote antenna units in a large geographical area or a metropolitan area, and the CB and each RAU pass through the optical fiber link. Connected to form a distributed metropolitan area antenna network.
  • the fiber link includes a WDM (Wavelength Division Multiplexing) WDM all fiber ring, an OADM (optical add-drop multiplexer) node, and a fiber branch.
  • the remote antenna unit downloads a certain wavelength of the optical fiber on the optical link at the OADM node through the optical interface (the optical interface uses the FC (Fibre Channel) interface), performs photoelectric conversion, and extracts the modulation through the band pass filter.
  • the carrier frequency signal on the light wave is processed by frequency conversion, and finally the carrier frequency signal is transmitted through the antenna.
  • the RAU receives the signal from the terminal, after down-converting and filtering, converts the signal into an optical signal, which is amplified by an EDFA (erbium-doped fiber amplifier), transmitted to the CB through the fiber link, and demodulated by the CB. Wait for processing.
  • EDFA erbium-doped fiber amplifier
  • RAU structure, RF front-end and antenna system are only frequency dependent, so different RF front-end and antenna systems can support different wireless standards, such as GSM (pan-European digital cellular mobile communication system), CDMA (multi-code division) Address access), UMTS (Universal Mobile Telecommunications System), WLA (Wireless Local Area Network), BWA (Broadcast Multiple Access), WiMAX (Worldwide Interoperability for Microwave Access), etc.
  • GSM pan-European digital cellular mobile communication system
  • CDMA multi-code division) Address access
  • UMTS Universal Mobile Telecommunications System
  • WLA Wireless Local Area Network
  • BWA Broadcast Multiple Access
  • WiMAX Worldwide Interoperability for Microwave Access
  • a base station In a traditional cellular network structure, one base station is responsible for one or several cells, and multiple base stations are required to complete full coverage within a metropolitan area or a large geographical area.
  • a centralized base station is equivalent to concentrating all base station resources together to form a large-capacity base station, each remote antenna unit is responsible for covering a small area, and multiple remote antenna units form a distributed overlay network.
  • the remote antenna unit is connected to the centralized base station through a WDM all-fiber ring network, and optical waves of different wavelengths are downloaded at the optical network node OADM, and then the wireless carrier frequency signal carried on the optical wave is distributed to the remote antenna unit through the optical fiber branch.
  • all carrier frequency signals In the downlink direction, all carrier frequency signals are sent by a centralized base station and transmitted to the remote antenna units via optical fibers.
  • Each remote antenna unit demodulates the signal and transmits it to the area covered by the transmitting antenna.
  • the upstream process is the opposite.
  • the centralized base station mainly includes a baseband processing unit (BBU), a radio cross-connect unit (RXC), and a sub-carrier multiplexing unit (SCM). , Optical Cross-Connection (OXC), Wavelength Division Multiplexing (WDM), Control Maintenance Module (CMM), Frequency Shift Keying Unit (FSK, Frequency Shift key) .
  • BBU baseband processing unit
  • RXC radio cross-connect unit
  • SCM sub-carrier multiplexing unit
  • OFC Optical Cross-Connection
  • WDM Wavelength Division Multiplexing
  • CCM Control Maintenance Module
  • FSK Frequency Shift Keying Unit
  • the baseband processing unit is mainly used for performing baseband processing (including encoding, modulation, decoding or demodulation, etc.) and partial radio frequency processing of all carrier frequency signals, including a baseband processing module and a radio frequency processing module.
  • the baseband processing module works in a resource sharing manner, that is, the baseband processing module forms a resource pool, which is dynamically connected with the radio frequency processing module, and outputs an analog intermediate frequency or radio frequency signal from the baseband processing unit.
  • the main function of the RF processing module is to convert the signal output from the downlink baseband processing unit into a radio frequency signal, or downconvert the uplink radio frequency signal into a baseband signal.
  • the RF cross-connect unit is used to complete the routing function of the analog IF or RF signal output from the baseband processing unit to the Subcarrier Modulation Unit (SCM).
  • SCM Subcarrier Modulation Unit
  • the subcarrier modulation unit includes a frequency shifting module, a modulation and multiplexing module, wherein the frequency shifting module functions to shift the frequency of the input carrier frequency signal to have a local modulation of not less than the number of carrier frequency signals.
  • the frequency modulation and multiplexing module is responsible for modulating one or more frequency-shifted carrier frequency signals onto a certain wavelength of light, and the modulation process is monitored by FSK.
  • the optical cross-connect unit is configured to perform a cross-connect function of light waves of different wavelengths output by the sub-carrier modulation unit to the corresponding WDM unit.
  • the wavelength division multiplexing unit is used to perform multiplexing functions of optical waves of different wavelengths to the optical fiber link.
  • Control the maintenance unit responsible for the management and maintenance of the CB system, configuration, monitoring, and troubleshooting of each module.
  • it is responsible for the cooperative processing of each module during virtual carrier frequency shifting, such as cross-interconnection of radio frequency signals, SCM modulation management, and wavelength routing management of optical cross-modules.
  • FSK is mainly responsible for the monitoring of SCM modulation.
  • CMM modulates its control SCM
  • the frequency modulation information such as the frequency of the carrier, the bandwidth of the adjacent carrier, etc., is sent to the FSK; the FSK detects the modulated carrier frequency information, which both indicate that the SCM modulation is correct, and conversely, the carrier frequency after the SCM modulation is incorrect. Or the error, then the FSI will send the modulation information to the CMM [reporting message, the CMM re-issues the modulation information, and the SCM re-modulates.
  • mapping relationship table T is stored in the CMM or the network management system based on the centralized base station access network, and the mapping relationship table T includes the following parameter list:
  • Carrier frequency signal list in which the carrier frequency signal of the BBU output is recorded, and N is the carrier frequency signal sequence
  • the frequency shift frequency list of the subcarrier modulation unit using the elements in the list to shift frequency / consult frequency shift the corresponding carrier frequency signal, correspondingly obtain the element / sn in the subcarrier modulation frequency list, n is frequency shifting The serial number of the frequency;
  • Cross-connect the list of wavelengths of light, where the element nurse is the wavelength
  • the wavelength of the light wave outputted by the light wave after passing through the optical cross-connect unit is the wavelength number of the light wave;
  • each WDM unit has a one-to-one correspondence with each optical fiber branch; a remote antenna unit ID list, in which an element is recorded as a remote antenna unit ID number, and the remote antenna unit has a fixed connection relationship with the optical fiber link, that is, each remote end
  • the antenna unit is connected to one of the fiber branches in the fiber link.
  • the mapping relationship table T of the parameter list reflects the radio resource configuration of the centralized base station access system. It contains the carrier frequency signal S in the carrier frequency signal list to the frequency shift frequency in the frequency shift frequency list.
  • mapping relationship table T finally establishes a mapping relationship between the wireless carrier frequency signal and the remote antenna unit.
  • mapping relationship table When configuring the mapping relationship table, two situations must be avoided: First, one or two or more co-frequency wireless carrier signals are carried on one optical wave; Second, two or more identical optical waves are carried on one optical fiber.
  • the wireless access system based on the centralized base station adopts a legality checking mechanism. Before the mapping relationship table T is configured or updated, the mapping relationship table is audited by the CMM or the network management system, and one of the above two situations occurs. It is considered illegal and resource allocation is prohibited.
  • the transmission, reception, and virtual carrier frequency of the carrier frequency signal are implemented by the following process:
  • the RF cross-connect unit routes the carrier frequency signal sent by the baseband processing unit to the subcarrier modulation unit by calling the carrier frequency signal list; the subcarrier modulation unit calls the frequency shift frequency list, the modulation frequency list, and the optical wavelength list, and the carrier frequency signal is used.
  • the frequency shift frequency in the subcarrier modulation unit the modulation frequency is generated, and then modulated and multiplexed onto the corresponding light wave of wavelength ⁇ .
  • the number of frequencies in the subcarrier frequency shifting frequency list is not less than the number of carrier frequency signals in the carrier frequency signal list, and the frequencies in the subcarrier frequency shifting frequency list are different, so as to ensure the modulation frequency generated after mixing with _ Different.
  • the subcarrier-to-lightwave multiplexing is in accordance with the mapping relationship between the carrier frequency signal list and the optical wavelength list.
  • the carrier frequency signal can be multiplexed into light waves of different wavelengths by software control, thereby realizing the movement of the carrier frequency signal on the carried light wave.
  • the optical cross-connect unit invokes the cross-connected optical wavelength list, and cross-connects the optical waves carrying the wavelength of the carrier frequency signal to output light waves of the wavelength.
  • the WDM unit calls the WDM list to multiplex the optical wave with a wavelength of 4m onto the corresponding element, and then sends it to the corresponding fiber link through the TOM/unit.
  • the software control can multiplex the optical waves carrying the carrier frequency signals onto different WDM units, thereby realizing the movement of optical waves on the fiber link.
  • the optical link has a fixed connection relationship with the remote antenna unit, and the optical fiber link includes WDM all-fiber ring network, OADM node and fiber branch ( Figure 1).
  • the remote antenna unit performs photoelectric conversion on the optical wave by downloading the optical wave of the wavelength on the optical link at the OADM node or by downloading the optical wave of the amplified wavelength through the optical interface (FC), and then passes the band pass.
  • the filter extracts the carrier frequency signal modulated onto the light wave, performs frequency conversion and the like, and finally completes the transmission of the carrier frequency signal through the antenna.
  • the wireless access system based on the centralized base station can complete the centralized processing and distributed transmission of the carrier frequency signal, and more importantly, realize the virtual carrier frequency shift without changing the hardware configuration, so as to be based on the centralization.
  • the wireless access system of the base station becomes a dynamic distributed system.
  • the principle of proximity is adopted when the virtual carrier frequency is moved, that is, the priority shift is prioritized.
  • the carrier signals of similar frequency are considered, and then the carrier frequency signals on the adjacent optical wavelengths are considered to be moved.
  • the carrier frequency signals on the adjacent optical fiber links are considered to be moved.
  • the remote antenna unit is mainly used to complete a PD/Photo Detector (LD, Laser Diode), which mainly includes: a fiber link interface unit, an RF front end, and an antenna system (Antenna). Wait.
  • the fiber link interface unit is responsible for downloading the optical wave on the fiber link to the RAU, or converting the uplink electrical signal received by the RAU into an optical signal and transmitting it to the fiber link.
  • the fiber link interface unit includes an optical circulator, a photodiode (PD), a laser diode (LD), an optical fiber amplifier (EDFA), and the like; the RF front end is used to modulate the downlink baseband signal into a radio frequency signal, or the uplink radio frequency signal Downconverted to baseband signals, including filters (BPF), mixers, power amplifiers (PA), low noise amplifiers (LNAs), and more.
  • the antenna system is used to transmit or receive RF signals.
  • the fiber link interface unit downloads one or more lengths of light from the fiber link and converts the optical signal into an electrical signal through a PD (photodiode).
  • the bandpass filter BPF filters out the carrier signal required by the RAU from the electrical signal, and then transmits it from the antenna through the upconversion process of the mixer and the amplification process of the power amplifier; in the uplink direction, the RAU receives from the antenna
  • the wireless signal is amplified by a low-noise amplifier, and then filtered by a mixer to select a wave and a band-pass filter to obtain an uplink RF electrical signal.
  • the LD laser diode
  • the centralized base station and the remote antenna unit use the optical circulator to multiplex one carrier frequency transmission and reception signal onto one fiber link.
  • a baseband processing unit internally forms a resource pool for performing baseband processing, dynamically processes the carrier frequency signal, and outputs an analog intermediate frequency or radio frequency (IF/RF) signal from the baseband processing unit (BBU).
  • the IF/RF signal is input to the RXC unit.
  • the IF/RF signal can be routed from the input port to the different output ports.
  • the IF/RF signal enters the SCM unit, and the SCM performs frequency shift processing on the carrier frequency signal using the local frequency shift frequency to obtain the SCM modulation frequency, and then modulates and multiplexes the frequency-shifted carrier frequency signal onto the optical wave.
  • the SCM unit includes a photodiode (PD), a laser diode (LD, Laser Diode), and a downstream filter (PFDL, Pass Filter of Downlink).
  • PD photodiode
  • LD laser diode
  • PFDL Pass Filter of Downlink
  • the light wave signal enters the OXC unit.
  • the OXC unit the light waves are cross-connected, so that each light wave can be outputted from different output ports of the OXC unit to different WDM units.
  • the OXC output port is directly connected to the WDM unit.
  • the WDM unit multiplexes the input optical wave onto the fiber link, and optically amplifies it and sends it to the remote antenna unit.
  • a light circulator is added after a group of WDM units responsible for transmitting and receiving.
  • the carrier frequency signal is frequency division multiplexed onto the optical wave
  • the optical wave is wavelength division multiplexed onto the optical fiber link.
  • the tunable 0ADM is used to distinguish the optical wave signal at the optical network node, and the remote antenna unit at the remote station distinguishes and downloads the wireless carrier frequency signal of different frequencies through the filter, thereby realizing the carrier frequency signal from the centralized base station to the far Smooth transmission of the end antenna unit.
  • the wireless access system based on the centralized base station of the present invention can implement virtual carrier frequency shift without changing hardware devices, and meet the requirements of wireless resource configuration for service changes.
  • the technical solution of the present invention realizes carrier frequency signals at different remote antenna units by using the radio frequency cross connection unit, the subcarrier modulation unit, the optical cross connection unit and the WDM unit in the centralized base station without changing the hardware configuration of the centralized base station.
  • the centralized base station lists the carrier frequency signal, the frequency shift frequency list of the subcarrier modulation unit, the modulation frequency list, the optical wavelength list, the cross-connected optical wavelength list, the WDM unit list, the fiber link list, and the remote antenna.
  • the unit list and the mapping relationship table T between the parameter lists are initialized, and the mapping relationship table T is stored in the control maintenance unit or the network management system of the centralized base station.
  • the footings of the symbols in the parameter list N, n, sn, m, sm, 1, and ? Respectively represent the serial numbers of the parameters in the list, and the mapping relationship table reflects the correspondence between the parameters of each list.
  • the control and maintenance unit or the network management system of the centralized base station calculates and updates the above lists and mapping relationship tables to ensure that two or more identical subcarrier frequencies are carried on one optical wave, thereby avoiding one aperture. Two or more identical light waves are carried on the upper side.
  • the virtual carrier frequency shift is implemented according to the new list and mapping relationship table.
  • the carrier frequency signal is routed to the subcarrier modulation unit through the RF cross-connect unit, and interacts with the frequency shift frequency in the subcarrier modulation unit to generate a subcarrier modulation frequency / OT , which is then modulated and multiplexed onto the wavelength of the light wave.
  • the carrier frequency signal can be moved on different bearer light waves by changing the mapping relationship between the carrier frequency signal and the subcarrier frequency shift frequency.
  • the light wave carrying the carrier frequency signal passes through the optical cross-connect unit and outputs the light wave of wavelength L to the WDM unit, and then passes through Multiplexed onto the fiber link. Moving virtual carrier frequency, by controlling the optical cross-connect cross-connect unit changes the relationship between the wavelength Jl m and A m, can be achieved in the light waves move fiber link.
  • the fiber link has a corresponding relationship with the remote antenna unit, and the remote antenna unit can identify and demodulate the carrier frequency signal, and then transmit it to the area covered by the signal.
  • the carrier frequency signal can be dynamically shifted on the centralized base station, the fiber link, and the remote antenna unit.
  • a carrier frequency signal & as an example to illustrate a specific virtual carrier frequency shifting process.
  • the wireless carrier frequency signal & transmission path is transmitted to the remote antenna unit with the ID number.
  • Sj is sent by the BBU unit, and is exchanged to the port of the subcarrier modulation unit by the RXC unit, which is the frequency shift frequency of the subcarrier modulation unit, and after the frequency shift processing by /, the frequency becomes the modulation frequency of the subcarrier modulation unit.
  • the RF signal with the frequency _;/ is modulated onto the optical wave of wavelength A, and the optical wave is cross-connected, and the optical wave of the wavelength A/ is outputted, and the optical wave is multiplexed to the DM via the optical fiber link.
  • the remote antenna unit downloads the carrier frequency signal & on the optical wave by photoelectric conversion and a band pass filter, and after being converted, is transmitted to the coverage area.
  • the mapping relationship between the mapping path and the line in the T is as follows:
  • the carrier frequency signal number has a mapping relationship with the remote antenna unit ID number, and the mapping satisfies the legality requirement, which completes the transmission and reception of the carrier frequency signal.
  • the wireless carrier signal & sent to the remote antenna unit scale ⁇ the mapping relationship meets the legality requirements.
  • the hardware configuration of the centralized base station is not changed, but the RXC unit, the SCM unit, the 0XC unit and the WDM unit are controlled by software to implement the carrier frequency signals on different wavelengths of light waves and different fiber links.
  • the migration therefore, enables virtual 3 ⁇ 4: shifting of the carrier frequency signal.
  • the centralized base station In a wireless access system based on a centralized base station, the centralized base station is easy to maintain and easy to expand; the WDM optical network is safe and reliable, and the frequency resources are abundant; the remote antenna unit hardware is simple, easy to install, robust, and maintenance-free. .
  • the virtual carrier frequency shifting technology greatly saves operators' investment.
  • the whole system can carry multiple types of wireless access systems, such as GSM, CDMA, UMTS, BWA, WiMAX and WLAN.

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  • Mobile Radio Communication Systems (AREA)

Abstract

La présente invention concerne un système d'accès radio à base de station de base centralisée. Ce système comprend une station de base centralisée (1) et quelques unités d'antennes à distance (2), qui sont reliées les unes aux autres par une liaison en fibre optique. La station de base centralisée (1) sert à la modulation d'un signal de porteuse et à son multiplexage donnant une onde lumineuse, puis à la modulation de l'onde lumineuse pour la liaison par fibre optique. Les unités d'antennes à distance (2) servent à la démodulation du signal de porteuse après réception de l'onde lumineuse en provenance de la liaison par fibre optique, et à l'émission du signal de porteuse en directions des zones de couverture au moyen des antennes émettrices correspondantes. L'invention concerne également un procédé à déplacement de fréquence utilisant le système d'accès radio. Ce procédé comporte plusieurs étapes. On commence par définir les relations de correspondance entre le signal de porteuse, la fréquence du déplacement de fréquence, la fréquence de modulation, la longueur d'ondes de l'onde lumineuse, et la liaison par fibre optique. Ensuite, la station de base centralisée (1) provoque les déplacements de fréquence du signal de porteuse puis module le signal de porteuse et le multiplexe, ce qui donne l'onde lumineuse correspondante telle qu'elle découle des relations de correspondance. La station de base centralisée (1) utilise alors la liaison par fibre optique correspondante pour envoyer l'onde lumineuse à l'unité d'antenne à distance correspondante (2).
PCT/CN2007/003952 2007-07-04 2007-12-29 Système d'accès radio à base de station de base centralisée et procédé à déplacement de fréquence WO2009003338A1 (fr)

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