CN100417252C - Mobile communication base station subsystem and method for transmitting data - Google Patents

Abstract

The invention relates to a mobile communication base station subsystem, and discloses a mobile communication base station subsystem and a data transmission method thereof, so that the erection of the mobile communication cell base station system is not hindered by the difficulty of laying physical links, and fast and flexible networking is realized. net. In the present invention, the communication link between each functional entity of the base station system is realized by the wireless link between the transmission carrier frequencies, and the wireless link between the transmission carrier frequencies is the original service carrier frequency communication link in the base station Based on simple improvements.

Description

Mobile communication base station subsystem and method for transmitting data

technical field

The invention relates to a mobile communication base station subsystem, in particular to a mobile communication base station subsystem based on wireless transmission.

Background technique

The Global System for Mobile Communications (GSM for short) is the second-generation cellular mobile communication system and the first digital cellular mobile communication system in the world to standardize digital modulation methods, network structures and service types. The services provided by GSM are divided into voice services, bearer services, supplementary services and short message services. The GSM system uses a Subscriber Identify Module ("SIM"). A SIM card is a memory that stores user-related information such as a user identification code, authentication and encryption information, and a 4-digit personal identification number. The user can get the service of the system on any GSM terminal through the SIM card.

The standard of the GSM system is formulated by the European Telecommunications Standards Institute (Europe Telecommunication Standard Institute, referred to as "ETSI"), and the GSM digital mobile communication system produced by any manufacturer must comply with the GSM technical specification. As an open structure and future-oriented design system, the GSM system has the following main features:

The GSM system consists of several subsystems, and can communicate with various public communication networks, such as Public Service Telecommunication Network (Public Service Telecommunication Network, referred to as "PSTN"), Integrated Service Data Network (Integrated Service Data Network, referred to as "ISDN") , Public Data Network (Public Data Network, referred to as "PDN") and other intercommunication and interconnection. The GSM system can provide automatic roaming across borders. In addition to providing user terminal services, such as voice services and emergency calls, the GSM system can also provide various bearer services, supplementary services and ISDN-related services. The GSM system has encryption and authentication functions, which can ensure the user's communication confidentiality and network security. The GSM system has a flexible and convenient network structure, which can meet the user's requirements for large-capacity and high-density services. The GSM system has strong anti-interference ability and good communication quality in the coverage area. GSM user terminal equipment adopts VLSI and digital signal processor, which are smaller in size, lighter in weight and stronger in function.

The GSM system consists of three interconnected main subsystems, which are connected to users through a certain network interface. The three subsystems are Base Station Subsystem (BSS for short), Network and Switching Subsystem (NSS for short), and Operation Supporting Subsystem (OSS for short). A mobile station (MobileStation, "MS" for short) is also a subsystem, but it is generally regarded as a part of the BSS.

In the GSM system, the BSS is responsible for providing and managing the transmission path between the NSS and the MS, especially including the radio interface management between the MS and the functional entities of the GSM system. The NSS is responsible for the management of communication services, ensuring that MS establishes communication with related public communication networks or with other MSs. That is to say, the NSS does not directly communicate with the MS, and the BSS does not directly communicate with the public communication network. MS, BSS and NSS form the physical part of the GSM system. OSS provides operators with the control, maintenance and management of these actual operating parts.

The mobile station is a practical device for users in the GSM mobile communication network. The types of mobile stations mainly include vehicle-mounted stations and handheld stations (mobile phones). Along with the digital mobile phone of GSM standard further develops to small, light and handy and multifunctional direction. In addition to providing conventional wireless communication functions and related processing functions that enter the GSM system through the wireless interface, the MS must also provide an interface with the user. For example, it provides the microphone, loudspeaker, display screen, and keyboard needed for calls; it also needs to provide interfaces with other terminal equipment, such as interfaces with personal computers and fax machines, when performing data communications. Another important part of MS is the SIM card. The GSM system identifies users through the SIM card. The application of the SIM card makes the mobile station not fixedly bound to one user, which lays a good foundation for the Personal Communication Service (PCS for short). Foundation.

BSS is the most closely related and most direct basic component to the wireless aspect in the GSM system. It sends and receives information wirelessly and manages wireless resources. On the other hand, the BSS is connected to the Mobile Switching Center (MSC) in the NSS to realize communication between mobile users or between mobile users and local users, and to transmit system information and user information. In order to operate, maintain and manage the BSS part, a communication connection between the BSS and OSS must also be established.

The BSS consists of two functional entities, the Base Transceiver Station (BTS for short) and the Base Station Controller (BSC for short). The BTS connected to the mobile station through the wireless interface and the BSC connected to the exchange on the other side, the BTS is responsible for wireless transmission, and the BSC is responsible for control and management. The BSS is composed of one BSC and one or more BTSs, and one BSC can control dozens of BTSs according to traffic demands. The BTS can be directly connected to the BSC, or can be connected to the BSC through a remote control connection through the Base Interface Equipment ("BIE"), and the connection link is generally wired. The BSS should also include a transcoder (Transcoder, "TC" for short) and a corresponding sub-multiplexer (Sub-Multiplexer, "SM" for short). The code converter is generally placed between the BSC and the MSC, so that the flexibility of networking is high and the number of transmission devices can be reduced. A typical BSS composition method with local and remote configuration BTS is shown in Fig. 1 .

BTS is a base transceiver station and an important part of BSS. It is controlled by the BSC, completes the conversion between the BSC and the wireless channel, and realizes the wireless transmission of the air interface between the BTS and the MS and related control functions. BTS is mainly composed of baseband unit, carrier frequency unit, control unit and antenna feeder unit. The baseband unit is mainly used for necessary voice and data rate adaptation and channel coding; the carrier frequency unit is mainly used for modulation/demodulation and the transmission and reception of radio frequency signals; the control unit is used for BTS operation and maintenance. The antenna feeder unit is mainly used for splitting/combining of radio frequency signals and converting radio frequency signals into electromagnetic waves or converting electromagnetic waves into radio frequency signals. When the BSC and BTS are not located at the same place, the transmission unit is necessary to realize the remote connection between the BSC and the BTS; if the BSC and the BTS are located at the same place, the transmission unit can be omitted.

The BSC is the control part of the BSS, which completes the management of various interfaces and undertakes the management of wireless resources and wireless transmission parameters. In addition, when the MS performs handoff (handoff, also called handover) between two BTSs under the control of the same BSC, the handover process is handled by the BSC instead of the MSC, which greatly reduces the processing load of the MSC. BSC is mainly composed of the following parts: the management, control and processing part of the relevant interface; the public processing part; the switching part.

NSS handles the exchange of external network and mobile user calls, and manages and operates some related user databases. The functions of NSS mainly include the exchange function of the GSM system and the database function required for user data, mobility management, and security management. With a management role.

MSC is the core of the entire GSM network. It controls all BSC services, provides switching functions and connections with other functions in the system, and provides interface functions with fixed networks such as PSTN, ISDN, and PDN. It connects mobile users with mobile users, Mobile users and fixed network users are connected to each other. MSC from the three databases in the system, namely Home Location Register (Home Location Register, referred to as "HLR"), Visit Location Register (Visit Location Register, referred to as "VLR") and Authentication Center (Authentication Center, referred to as "AUC") All data required for user location registration and call requests are obtained in the . In addition, MSC also requests to update part of the data in the database according to its latest acquired information. As the core of the network, MSC also supports functions with mobile features such as location registration, handover, and automatic roaming, as well as other network functions.

VLR serves the mobile users in its control area, stores the relevant information of registered roaming mobile users entering its control area, and provides the registered roaming mobile users with the necessary conditions to establish call connection. The VLR obtains and stores necessary data from the mobile subscriber's HLR. Once this mobile user leaves its control area, then register again in another VLR, and former VLR deletes the data of this mobile user of temporary record. Therefore, VLR can be regarded as a dynamic user database.

HLR is the central database of the GSM system, which stores the relevant data of all registered mobile users controlled by the HLR. One HLR can control several mobile switching areas and even the entire mobile network. All important static data of mobile users are stored in the HLR, including data such as mobile user identification numbers, access functions, user categories, and supplementary service functions. The HLR also stores and provides the MSC with relevant dynamic data about the MSC where the mobile user actually roams. In this way, any incoming call can be routed to the called user accordingly.

The GSM system has taken special security measures, such as user authentication, encryption of information on the wireless interface, and so on. The AUC stores authentication information and encryption keys, which are used to prevent unauthorized users from accessing the system and ensure the communication security of mobile users communicating through the wireless interface.

It can be seen that in the existing GSM system, the connections between the functional entities BSC or BTS of the BSS are all realized by wired links. In fact, when a BSC controls multiple BTSs, it may be that the BSC is directly connected to multiple BTSs through a star-shaped link network, or it may be that the BTSs are connected in a cascading manner, and then connected to the BSC. No matter which connection method is used, the connection between BSC and BTS, and between BTS and BTS is realized through the laying of wired communication links, such as E1 lines and other wired links that can transmit large amounts of data.

On the other hand, the wireless communication between BTS and multiple MSs is realized by using wireless links, which is the basic characteristic of wireless communication. In each cell, multiple MSs are connected to the BTS through digital technologies such as Time Division Multiplexing (TDM for short) or Frequency Division Multiplexing (FDM for short). BTS uses one service carrier frequency to complete wireless communication with multiple MSs.

In practical application, the above scheme has the following problems: in some application environments, such as remote mountainous areas with steep terrain, closed building spaces, etc., due to the difficulty of laying lines, it is difficult to implement the distributed architecture of the entire base station system, or It takes a lot of manpower and material resources to set up, which seriously hinders the improvement of mobile communication network coverage.

The main reason for this situation is that the connection links between the various functional entity parts of the base station subsystem are all wired links, which can only be realized by physical laying. The functional entity parts are erected separately from each other, which leads to difficulties in laying wired links and realizing base station subsystems.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a mobile communication base station subsystem and its data transmission method, so that the erection of the mobile communication cell base station system will not be hindered by the difficulty of laying physical links, and realize fast and flexible networking. net.

To achieve the above object, the present invention provides a mobile communication base station subsystem, comprising at least one base station controller and at least one base transceiver station,

Wherein, the base transceiver station receives the control of the base station controller, and provides an air interface to the mobile station through a service carrier frequency to realize wireless communication with it; the base station controller controls the base transceiver station to complete network-side Interface communication management, and management of wireless resources and wireless transmission parameters, also includes at least one wireless transmission link, used to connect the two functional entities of the base station subsystem, wherein the service carrier frequency is a related functional module dedicated to the transmission of service data Or equipment, the functional entity is a physically independent device that implements a specific function, and the two ends of the wireless transmission link are transmission carrier frequencies using fixed wireless communication control technology, and the transmission carrier frequency is used to transmit general data-related functions module or device.

Wherein, the wireless transmission link is used to connect the base station controller and the base transceiver station.

Also in the system, the wireless transmission link is used to connect different base transceiver stations.

In addition, in the system, the transmission carrier frequency combines all multiplexing channels into one high-speed channel;

The transmission carrier frequency is set with a frame structure compatible with other wired links in the mobile communication base station subsystem.

In addition, in the system, the mobile communication base station subsystem is applied to the Global System for Mobile Communications.

In addition, in the system, both the transmission carrier frequency and the service carrier frequency adopt Gaussian minimum frequency shift keying modulation.

In addition, in the system, the power ramp control is adopted in the service carrier frequency, and the power ramp control is removed from the transmission carrier frequency.

The present invention also provides a method for transmitting data through the transmission carrier frequency, which is applied to the communication between the transmission carrier frequencies at both ends of the wireless transmission link in the above-mentioned system, including the following steps:

At the sending end, the transmission carrier frequency convolves the data to be transmitted; then adds the training sequence, protection bits, and bit number identification; finally encodes it and transmits it on the wireless transmission link;

At the receiving end, the transmission carrier frequency is adjusted and synchronized according to the training sequence; then deconvolution decoding is performed to extract data.

Wherein, the adjustment synchronization of the transmission carrier frequency at the receiving end further includes the following sub-steps:

Periodically adjust the time offset of the receiving window;

Calculate the frequency difference between it and the sending end by receiving the training sequence or the data to be transmitted, and adjust its local frequency accordingly.

By comparison, it can be found that the main difference between the technical solution of the present invention and the prior art is that the wireless link between the communication links between each functional entity of the base station system (between the BSC and the BTS or between the BTS and the BTS) uses the transmission carrier frequency The wireless link between the transmission carriers is realized through simple improvement on the basis of the original service carrier communication link of the base station.

The difference in this technical solution has brought obvious beneficial effects, that is, the method of using the transmission carrier frequency wireless link to realize the communication between various functional entities of the base station system solves the problem of areas where transmission equipment cannot be laid or the cost of laying transmission equipment is high. Compared with wireless communication, it has the advantages of low cost and fast network construction, which is conducive to improving coverage and business volume;

Based on the improvement of the existing service carrier frequency wireless link, the transmission carrier frequency adopts the GSM frequency band for wireless transmission, which can save frequency resources and technology development costs.

Description of drawings

Fig. 1 is the composition block diagram of GSM system base station subsystem;

Fig. 2 is a schematic diagram of a base station subsystem based on wireless transmission according to an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

The basic idea of the present invention is to improve the wireless communication based on the existing service carrier frequency into a transmission carrier frequency, establish a wireless link to replace the current wired link, avoid problems such as line laying, and conveniently realize the establishment and assembly of the GSM base station system. net. The base station subsystem includes two transmission carriers and related equipment. The transmission carriers are two ends of a wireless link, which respectively belong to two functional entities of the BSS. The link realizes wireless communication between the two functional entities. The "carrier frequency" in this article refers to the functional modules or devices related to data transmission on a certain frequency. If it is dedicated to the transmission of business data, it is called "service carrier frequency". If it is used for transmission between two functional entities General data is called "transmission carrier frequency". A functional entity herein refers to a physically independent device for realizing a specific function, such as a base station, a base station controller, and the like.

It can be seen that the key point of the system is to use at least one wireless link to connect different functional entities to construct the entire base station subsystem. The wireless link can be improved and developed on the basis of existing GSM service carrier frequency wireless communication. As mentioned above, the BSS is composed of a BSC and a plurality of BTSs, and the connection relationship between them can be cascaded, so the wireless links proposed by the present invention can be based on specific needs, such as which links have physical laying difficulties when building a base station, Instead, decide whether to use a wireless link instead. Therefore the wireless link may be a connection between a BSC and a BTS or between a BTS and a BTS. In this way, the BSS system has two types of carrier frequencies, one is the original service carrier frequency for realizing MS wireless communication, and the other is the transmission carrier frequency.

A basic gist of the present invention can be summarized from the above statement: that is to use wireless transmission links instead of wired links that are difficult to lay to realize communication between different functional entities of the base station subsystem. Fig. 2 shows a block diagram of a base station subsystem based on wireless transmission according to an embodiment of the present invention.

The BSS system in the figure includes at least one BSC and at least one BTS. As mentioned above, multiple BTSs can be connected to a BSC according to a star network structure, as shown on the left side of the figure; they can also be connected in a cascaded manner, as shown on the right side of the figure. On the user side, the BTS in each cell is responsible for providing the MS with an air interface to realize its wireless communication, which is realized by the service carrier frequency of the BTS, and at the same time, the BTS receives the control of the BSC on the other side. On the network side, the BSC is responsible for controlling multiple BTSs, completing the communication management of multiple interfaces, and managing wireless resources and wireless transmission parameter configurations. Meanwhile, the BSC continues to communicate upwards with the switching center MSC of the entire mobile network.

In the first embodiment of the present invention, the BSS based on wireless transmission also includes at least one wireless transmission link, which is used to connect two functional entities whose physical distribution is far apart or separated relatively seriously, so as to realize the BSS which is difficult to complete by physical lines System internal communication. Both ends of the wireless transmission link are transmission carrier frequencies, as shown in FIG. 2 . The realization of the wireless transmission link can refer to the realization of the service carrier frequency air interface link between the MS and the BTS in the existing system. It is not difficult for those skilled in the art to transfer the wireless link from the MS to the BTS based on the service carrier frequency. To realize a wireless transmission link based on a similar transmission carrier frequency.

Of course, there are various possibilities for specific application situations, for example, it may be that the link between the BSC and the BTS is difficult to lay, and it may also be between the BTS and the BTS in a cascade connection mode, so in the second embodiment of the present invention In the wireless transmission-based BSS, the wireless transmission link is used to connect the BSC and BTS, as shown on the left side of Figure 2, this application may also occur in the case of BTS cascading, so at this time there is at least one BTS and BSC directly connected. In the third embodiment of the present invention, the wireless transmission link in the BSS based on wireless transmission is used to connect different BTSs, as shown on the right side of FIG. 2 , this situation only occurs in the case of cascading BTSs.

It can be seen that the present invention implements the erection of the BSS system, which is difficult to realize originally, through the wireless transmission link, and brings beneficial effects in many aspects. For example, it has similar application value to the existing repeater technology, and has more advantages compared with the repeater: good communication quality and strong network integrity. In addition, the realization of wireless transmission also has the following advantages: no other transmission equipment is required, and it has the advantages of fast network construction; it is especially valuable for places where transmission equipment cannot be erected; for overseas operators, microwave transmission can be omitted The frequency occupancy fee is increased; the coverage rate is improved, and fast and flexible networking is realized. The application of the invention can solve the problem of wireless communication in areas where transmission equipment cannot be laid or the cost of laying transmission equipment is high, and the cost is low and the network construction speed is fast.

Considering the convenience of upgrading existing network equipment, it is necessary to provide a convenient, feasible and low-cost technical solution for upgrading the newly added wireless transmission link, so as to ensure that the wireless transmission solution can continue to have the above advantages. Accordingly, on the basis of the second and third embodiments, the fourth embodiment of the present invention provides an upgrade solution for establishing a wireless transmission link. Based on the existing service carrier frequency, appropriate improvements are made to obtain the transmission carrier frequency. For example, the multiple access multiplexing function of the service carrier frequency can be improved to be more suitable for single large-capacity data channel transmission, and the power control for mobile access can be simplified to the power control required by the wireless communication of the fixed peer, etc. (see Hereinafter, the implementation technical details of the transmission carrier frequency in this embodiment), so as to establish a wireless transmission link, that is, the implementation principle of the transmission carrier frequency is the same as that of the service carrier frequency.

Compared with the original service carrier frequency, the improved transmission carrier frequency has the following differences:

First of all, the data volume transmission channel is more concentrated and has a larger capacity. This is because the transmission channel is mainly used for large-scale direct data transmission, so there is no need to perform a multiplexing mechanism similar to the service carrier frequency for multiple MSs, and directly combine multiple channels. as a highway;

Secondly, technologies such as power control related to mobile communication are simplified. This is because the wireless transmission link corresponding to the transmission carrier frequency is no longer the mobile terminal corresponding to the service carrier frequency, but two fixed opposite ends. There is no need to adopt the power control technology related to mobile communication, but only the control technology related to fixed wireless communication;

In addition, because the transmission carrier frequency must be compatible with other existing wired links such as E1 lines, it is necessary to adopt frame length and frame structure settings similar to E1 lines, which is also different from existing service carrier frequencies.

The following takes the GSM system as an example to describe in detail the implementation technical details of the transmission carrier frequency.

First of all, the same as the service carrier frequency, the transmission carrier frequency still uses the Gaussian Mean Shift Keying ("GMSK" for short) modulation method. GMSK modulation method. It has good power spectrum characteristics, relatively worrying bit error performance, especially small out-of-band radiation, and is very suitable for working in very high frequency bands (Very High Frequency, referred to as "VHF") and very high frequency bands (Ultra High Frequency, referred to as "UHF") mobile communication system. The basic working principle of GMSK with Gaussian filtering before modulation is to shape the baseband signal through a Gaussian filter first, and then perform minimum shift keying (MSK) modulation. Since the shaped Gaussian pulse envelope has no steep edges and no inflection points, the spectral characteristics are better than those of MSK signals.

Secondly, the power ramping control is adopted in the service carrier frequency, and the power ramping control is removed in the transmission carrier frequency, because the functional entities at both ends of the transmission carrier frequency are fixed, and some complicated control technologies in mobile communication are not required. This can reduce system complexity and reduce system upgrade costs.

The premise of the above solution is that BSC and BTS support 16K transmission, RSL and OML each occupy a 16Kbps bandwidth, 6 TCHs occupy 6x16Kbps, the carrier frequency BCCH and SDCCH do not occupy additional Abis transmission resources; the service carrier frequency GPRS is not supported CS3/CS4 business.

In a specific application, for example, since the GMSK modulation rate is 270.833Kbps, the effective data rate required to be transmitted within the BSS is 128Kbps if the above prerequisites are met, so the double convolution method can continue to be used. In addition, it will take a longer time to include a training sequence, for example, data positioning and synchronization measures and the training sequence together occupy 270.833-128*2=14.833Kbps wireless transmission resources. As for the synchronization problem of the sending and receiving ends, the sending and receiving is carried out in a time period of 6 ms, which is equivalent to 48 E1 frames, and each E1 frame is 125 us, which can contain 768 data before convolution.

In the fifth embodiment of the present invention, on the basis of the fourth embodiment, the communication process between the transmission carriers at both ends of the wireless transmission link includes the following steps: at the sending end, the transmission carrier convolves the data to be transmitted ; Then add training sequence, protection bit, bit number identification; finally encode it and transmit it on the wireless transmission link. At the receiving end, the transmission carrier frequency is adjusted and synchronized according to the training sequence; then deconvolution decoding is performed to extract data.

Wherein, at the receiving end, the transmission carrier frequency is adjusted and synchronized by periodically adjusting the time deviation of the receiving window. In addition, the transmission carrier frequency at the receiving end calculates the frequency difference between it and the sending end by receiving the training sequence, and thereby adjusts its local frequency to realize adjustment synchronization.

Taking the above application situation as an example, the specific actions of the transmission carrier frequency in the communication process are further described. On the basis of the existing carrier frequency base station, the above functions can be completed by slightly improving the two transmission carrier frequencies and the service carrier frequency.

When the transmitting end transmits the carrier frequency to process the downlink transmission data, it adds 2 training sequences (52 bits ) are sent together with 15 protection bits and 6 codes identifying the effective number of bits of the transmitted data. Correspondingly, the transmission carrier frequency at the receiving end needs to be adjusted for synchronization, deconvolution and decoding, and finally extract the data.

The key issue here is to adjust the synchronization. Due to the uncertainty of the distance between the transmitting and receiving transmission carrier frequencies, the 6ms timing boundary needs to be adjusted at the beginning, and the adjustment can be adjusted by the deviation calculated according to the position of the training sequence. At the same time, due to the inconsistency of the wireless port frequencies between the carrier frequencies, the receiving 6ms window data of the carrier frequency at the receiving end will be offset. Therefore, in the sixth embodiment of the present invention, the carrier frequency at the receiving end periodically adjusts the receiving window to cope with this situation.

In addition, the carrier frequency of the receiving end processes the data sent by the carrier frequency of the transmitting end through demodulation to obtain the data before convolution. It is considered a frequency adaptation problem: the carrier frequency at the receiving end needs to adjust the receiving demodulation clock. If the transceiver clock rate deviates, it will cause the training sequence to be gradually misaligned after synchronization in the initialization phase; and if the data rate of the transmitting and receiving carrier frequency or If the E1 data rate is inconsistent, it will lead to code slippage. For these two cases, the eighth embodiment of the present invention realizes frequency synchronization through frequency difference adjustment, that is, the number of digits of the training sequence in the receiving window deviation of the training sequence in the data received by the carrier frequency of the receiving end per unit time, the deviation of the technical transceiver clock, or The clock frequency deviation between sending and receiving is calculated according to whether the number of bits in the receiving window of the data received per unit time is consistent, so as to adjust the clock.

Those skilled in the art can understand that the above-mentioned descriptions about the embodiments of the present invention all take the GSM system as an example. For other mobile communication systems, if it is also necessary to set up a plurality of functional entities consisting of BSC and BTS or similar The composed base station subsystem can also realize the invention goal of feasible fast and flexible networking through the method of the present invention, without affecting the essence and scope of the present invention.

Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the present invention. The spirit and scope of the invention.

Claims (9)

1. A mobile communication base station subsystem, comprising at least one base station controller and at least one base transceiver station, Wherein, the base transceiver station receives the control of the base station controller, and provides an air interface to the mobile station through a service carrier frequency to realize wireless communication with it; the base station controller controls the base transceiver station to complete network-side Interface communication management, and management of wireless resources and wireless transmission parameters, also includes at least one wireless transmission link, used to connect the two functional entities of the base station subsystem, wherein the service carrier frequency is a related functional module dedicated to the transmission of service data or a device, the functional entity is a physically independent device that implements a specific function; It is characterized in that the two ends of the wireless transmission link are transmission carrier frequencies using the control technology of fixed wireless communication, and the transmission carrier frequencies are functional modules or devices related to the transmission of general data. 2. The mobile communication base station subsystem according to claim 1, wherein the wireless transmission link is used to connect the base station controller and the base transceiver station. 3. The mobile communication base station subsystem according to claim 1, wherein the wireless transmission link is used to connect different base transceiver stations. 4. The mobile communication base station subsystem according to any one of claims 1 to 3, wherein the transmission carrier frequency combines all multiplexing channels into a high-speed channel; The transmission carrier frequency is set with a frame structure compatible with other wired links in the mobile communication base station subsystem. 5. The mobile communication base station subsystem according to any one of claims 1 to 3, wherein the mobile communication base station subsystem is applied to the Global System for Mobile Communications. 6. The mobile communication base station subsystem according to claim 5, wherein the transmission carrier frequency and the service carrier frequency both adopt Gaussian minimum frequency shift keying modulation. 7. The mobile communication base station subsystem according to claim 5, wherein the power ramp control is adopted in the service carrier frequency, and the power ramp control is removed from the transmission carrier frequency. 8. A method for transmitting data by a transmission carrier frequency, applied to the communication between the transmission carrier frequencies at both ends of the wireless transmission link in the system according to claim 1, is characterized in that, comprising the following steps: At the sending end, the transmission carrier frequency convolves the data to be transmitted; then adds the training sequence, protection bits, and bit number identification; finally encodes it and transmits it on the wireless transmission link; At the receiving end, the transmission carrier frequency is adjusted and synchronized according to the training sequence; then deconvolution decoding is performed to extract data. 9. The method for transmitting data by a transmission carrier frequency according to claim 8, wherein the adjustment synchronization of the transmission carrier frequency at the receiving end further comprises the following sub-steps: Periodically adjust the time offset of the receiving window; Calculate the frequency difference between it and the sending end by receiving the training sequence or the data to be transmitted, and adjust its local frequency accordingly.

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