CN1330143C - Method of composing broadband radio city local network for providing hierarchical serivce - Google Patents

Abstract

The invention belongs to the technical field of broadband wireless metropolitan area network, and relates to a method for constructing a broadband wireless metropolitan area network providing graded services by using 802.16 wireless transmission technology. The method proposes the broadband wireless metropolitan area network system structure and network protocol stack model, base station protocol stack structure, network topology and wireless station voice communication flow. Voice communication belongs to a level of hierarchical services, and its communication process includes: the calling wireless station applies for control bandwidth and service bandwidth to the entrance base station, and the base station allocates the requested bandwidth to the wireless station according to the usage status of wireless resources; the calling party initiates a call request , the base station queries the network for the IP address corresponding to the called number; the metropolitan area network starts the process of route discovery, resource reservation, and label switching path establishment, and establishes a layer-2 exchange meeting specific quality requirements between the calling party and the called party path; the call starts, and the network charges; after the call ends, the relevant network resources are released.

Description

A Construction Method of Broadband Wireless Metropolitan Area Network Providing Hierarchical Services

technical field

The invention belongs to the technical field of broadband wireless metropolitan area network (IEEE802.16 WirelessMAN), and relates to a method for constructing a broadband WirelessMAN providing hierarchical services.

Background technique

IEEE802.16 WirelessMAN is a broadband network capable of providing high-speed wireless access within a metropolitan area [1] Carl Eklund, Roger B.Marks, "IEEE Standard802.16: ATechnical Overview of the WirelessMAN ^TM Air Interface for BroadbandWireless Access" , IEEE C802.16-02/05, 2002. The IEEE802.16 working group released IEEE Std802.16-2004 on October 1, 2004. This standard defines the air interface physical layer (PHY) and media access of fixed broadband wireless access systems operating in the 2-66GHz frequency band. Control Plane (MAC) specification. IEEE Std802.16e will be issued in March 2005, which defines the air interface specification of the mobile broadband wireless access system. The working group of IEEE802.16 has only made the air interface standard of the broadband wireless access system, but has not made the standard of constructing the broadband wireless metropolitan area network by using the IEEE802.16 wireless access technology.

Contents of the invention

The purpose of the present invention is to provide a method for constructing a broadband wireless metropolitan area network providing graded services by using IEEE802.16 wireless access technology.

The broadband wireless metropolitan area network system can be divided into three subsystems: base station system, switching subsystem, and management subsystem.

The base station system realizes wireless channel interconnection between IEEE802.16 terminals and base stations, and wireless interconnection between base stations. The switching subsystem has all the functions of managing signaling procedures, and is used to control and manage the establishment, maintenance and removal of calls. The main functions included in the switching subsystem are: special functions related to user mobility; management of wireless resources; management of signaling procedures; mobile terminal registration; user identity authentication; routing selection; label switching path establishment. The management subsystem remotely controls and maintains the entire wireless metropolitan area network. Its main functions include: network operation management, including user management, network equipment management, billing, statistics, etc.; security management; operation and performance management; system change control; System maintenance and failure recovery.

The broadband wireless metropolitan area network system structure is shown in Figure 1. The entire communication network is composed of wireless network, wired network and other networks; the broadband wireless metropolitan area network includes two parts: wireless network and wired network, and other networks include PSTN, ISDN, GSM and 3G and other existing voice communication networks; the broadband wireless metropolitan area network is interconnected with other networks through the conversion gateway of the switching center. The functional entities that make up the broadband metropolitan area network include: wireless station, switching center, base station, access center, device marker, registration center, authentication center, management center, and billing center. The first three entities belong to the wireless network part, the last six entities belong to the wired network part, and the access center completes the interconnection between the wireless network and the wired network. The functional entities in the wireless network are connected through wireless links; the wired network adopts the traditional IP network, and the functional entities are interconnected through optical fibers. Each entity performs a specific function.

Wireless station: The wireless station is composed of user equipment and supports IEEE802.16-2004 and IEEE802.16e protocols. Users can use these devices to access IEEE802.16 metropolitan area network fixedly or mobilely, and obtain the required communication services. Each wireless station includes a wireless terminal, and according to the needs of communication services, the wireless station can also include various terminal equipment and terminal adapters. A wireless station has several identification numbers, which are used to uniquely identify the wireless station within a certain range.

Base Station System: A base station system consists of equipment that establishes radio coverage within a certain area and communicates with wireless stations. The base station system consists of two types of functional entities, the base station controller and the base station transceiver equipment. The base station controller controls and manages the base station transceiver equipment; the base station transceiver equipment is a radio transceiver equipment covering a certain area. The base station system supports IPv6 routing and MPLS (Multi-Protocol Label Switching) switching. The base station system assigns a home IP address or a care-of IP address to the accessing wireless station.

Switching center: The switching center switches and controls wireless stations located in its service area, and provides interfaces with other base stations at the same time. The switching center can complete functions such as call connection, data forwarding, radio resource management, and mobility feature management.

Access center: Complete the access functions of wireless network and wired core network, including data forwarding, routing selection, switching path establishment, etc.; also provide interfaces with other networks to complete switching and control with other networks.

Registration center: The registration center is a database used for wireless access user management, and each user must be registered in the registration center. The registration center records the mapping between the IP address and the wireless station identification code for the wireless station user.

Device marker: The device marker is a database that stores the parameters of the wireless station equipment, and realizes the functions of identifying, monitoring, and blocking the wireless station equipment.

Authentication center: The authentication center is a functional entity that authenticates the identity of wireless access users and generates corresponding authentication parameters. These parameters include random numbers, keys, etc. The authentication center authenticates any user trying to access the network, and only legitimate users can access the network and receive services.

Management center: The management center is a functional entity for network operators to monitor and operate the entire network.

Billing center: The billing center charges voice and data communication services of different grades and different service quality requirements.

The protocol stack model of the broadband wireless metropolitan area network is shown in Figure 2. The wireless station and the base station communicate through the physical layer (orthogonal frequency division multiple access OFDMA mode, 2-11GHz) and the MAC layer protocol defined by IEEE802.16. The base station communicates with the base station through the IEEE802.16 physical layer (single carrier SC mode, 10-66GHz) defined by IEEE802.16 and the PPP (Point to Point Protocol) protocol defined by IETF (Internet Engineer Task Force) using directional antennas. The base station communicates with the wired network through the physical layer and MAC layer protocols defined by IEEE802.3. Each functional entity in the wired network communicates through the core IPv6 network. In the protocol stack model in Figure 2, the third layer is divided into two sub-layers. The radio resource management sublayer manages the radio resources of the IEEE802.16 access part, including power control, channel allocation, user authentication, and so on. The IP sublayer processes Internet protocols, including IP (v6) route establishment, MPLS label switching path establishment, route lookup and data forwarding, etc. The above three layers are divided into mobile management sub-layer, call management sub-layer and network maintenance sub-layer. The mobile management sublayer supports and manages the mobile characteristics of wireless stations, including internal handover and handover. The call management sublayer supports and manages the communication of voice users, including call connection, QOS (Quality of Service, quality of service) request, resource application and release, etc. The network maintenance sublayer provides support for remote control and maintenance of the entire wireless metropolitan area network.

In the broadband wireless metropolitan area network system proposed by the present invention, the IEEE802.16 base station is the core equipment for network wireless access. The present invention requires that the base station can support quality-guaranteed voice communication and reliable multimedia data communication, and has good access control, power control, mobile switching control and capacity expansion capabilities, and supports wireless access of IEEE802.16x series terminals, and supports Routing and label path exchange between base stations, support connection with core IPv6 network, support IPv6 and MPLS protocols. The structure of the base station protocol stack is shown in Figure 3. The physical layer of the base station supports IEEE802.16 PHY (Orthogonal Frequency Division Multiple Access OFDMA and Single Carrier SC mode) and IEEE802.3 PHY. The base station data link layer supports IEEE802.16 MAC, IEEE802.3 MAC and IETF PPP protocols. The network layer of the base station supports MPLS protocol, IP, IPv6 protocol and radio resource management protocol. The radio resource management protocol manages and controls various wireless resources of the base station to ensure the effective allocation and reliable recovery of resources. On the network layer, the base station supports TCP/UDP transmission protocol and OSPF (Open Shortest Path First) routing protocol, supports label distribution LDP (Label Distribution Protocol) protocol, resource reservation RSVP-TE (Resouce Reserve Protocol extended for Traffic Engineering) protocol, mobile management signaling system, call management signaling system, network maintenance signaling system and various application layer network protocols. The mobile management signaling system manages the work related to terminal mobility, including processing data from the home agent of the mobile terminal. When a new user moves and joins the base station, the mobile management system orders the specific service aggregation subclass of the MAC layer of IEEE802.16 The Service-specific Convergence Sub-layer (CS) establishes a new connection, provides corresponding QOS parameters, and participates in scheduling; when the user leaves, the mobile management system notifies the radio resource management system to take back the connection and system resources belonging to the mobile terminal. The call management signaling system sends, receives and processes various voice communication signaling messages, realizes normal connection and mobile switching of voice communication, and realizes reasonable resource reservation through the wireless resource management system to ensure the service quality of calls. The network management signaling system provides the communication functions required for network operation management, security management, operation and performance management, system change control, system maintenance and fault recovery.

Fig. 4 is a topological structure of a broadband wireless metropolitan area network providing hierarchical services constructed by the method proposed in the present invention. Metro core network, base stations and IP mobile phones all support IPv6 protocol; base stations and core network routers (including access routers) also support OSPF routing protocol, MPLS label switching protocol and RSVP-TE resource reservation protocol; The data link layer runs the PPP protocol. The bandwidth between base stations is divided into control bandwidth and service bandwidth. The control bandwidth is used to transmit network management and service control signaling, and the service bandwidth is used to transmit service data. IP mobile phones and base stations also support IEEE802.16-2004 and IEEE802.16e protocols. The access router (MPLS router) and IEEE802.16 base station complete the function of the switching center, select the route for the IP data packet, establish the switching path for the voice stream, and forward the voice or data from the IP mobile phone to the next hop at high speed Routers (including base stations). Authentication server, registration server, management server, access router and base station jointly complete wireless resource management, such as power control, admission control, channel allocation, and mobile handover. The management server is also responsible for remote management of devices in the entire network, including system maintenance, fault recovery, and user management. AAA (Authentication, Authorization and Accounting) server authenticates, authorizes and accounts for voice or data communication on the network. Ordinary data packets entering access base stations and routers go through Layer 3 routing, and data packets and voice flows with QOS requirements go through Layer 2 switching. The authentication server, registration server, management server and AAA server are distributed on the core IPv6 network according to a certain strategy, and communicate through corresponding signaling systems (including voice communication signaling system, mobile management signaling system and network maintenance signaling system, etc.), Complete the coordinated control function. Switching gateways provide interfaces with other networks (such as PSTN, ISDN, GSM, 3G), and complete call connection and switching between broadband wireless metropolitan area network and other networks.

The subscriber identification code (such as a telephone number) of the IP mobile phone is fixedly allocated in advance, for example, can be solidified in the subscriber identification module. When the IP mobile phone is turned on, it first performs device identity authentication and user identity authentication (the authentication server and the registration server participate in the completion), and after the authentication is passed, the IP mobile phone accesses the base station from the access base station (for example, the access base station of the IP mobile phone 1 is an IEEE802.16 base station 1) to obtain an IPv6 address, and then register the address and its own phone number with the registration server, and establish a mapping from the phone number to the current IP address in the registration server. The initialization process of the wireless station entering the network is shown in Figure 5.

IEEE802.16 provides four different types of services: Unsolicited Grant Service (UGS), Real-time Polling Service (rtPS), Non-real-time Polling Service (Non-real-time Polling Service) , nrtPS) and Best Effort (BE). UGS services are used for real-time data streaming at a fixed bit rate, such as IP telephony. RtPS services are used for real-time data streams with non-constant bitrates, such as MPEG video. NrtPS is used for non-real-time data streaming with a non-constant bit rate, such as FTP file transfer. The BE service is used for services that do not have special QOS requirements and only require best effort. Services with different service levels and service quality requirements request system resources through these four different types of services, and the base station schedules system resources according to the QOS parameters requested by wireless stations, thereby realizing hierarchical services.

When the IP mobile phone 1 calls the phone number of the IP mobile phone 2, it first performs call level authentication, and after being authenticated and authorized by the AAA server, it queries the registration server for the current IP address of the IP mobile phone 2. After obtaining the IP address of IP mobile phone 2, IEEE802.16 base station 1 immediately starts the pathfinding mechanism and resource reservation mechanism, establishes a route from IP mobile phone 1 to IP mobile phone 2 that meets specific QOS requirements, and establishes a two-way network through MPLS protocol at the same time. layer switching path. After the switching path is established, mobile phone 1 and mobile phone 2 start talking, and the AAA server starts charging. After the call ends, the wireless and wired resources reserved for this call are released. The voice communication process in the broadband wireless metropolitan area network is shown in Figure 6.

The present invention uses IEEE802.16 wireless transmission technology to build a broadband wireless metropolitan area network with hierarchical service capabilities; uses the IEEE802.16 protocol-based broadband wireless metropolitan area network system structure, broadband wireless metropolitan area network protocol stack model, and broadband wireless metropolitan area network Base station protocol stack structure and metropolitan area network topology structure, the interface between base stations is added to the IEEE802.16 base station, allowing multi-hop wireless connections between base stations, expanding the wireless coverage area of the metropolitan area network, and adopting resource reservation protocols on the metropolitan area network Ensure the service quality requested by the business, use the MPLS protocol to establish a layer-2 switching path, provide support for high-level and high-QOS-required services, use four different types of services provided by IEEE802.16 to implement hierarchical service requests, and use layer-2 switching to ensure good voice call quality.

The present invention uses four different service types provided by IEEE802.16 to support hierarchical services, so that different services can be transmitted in the network with different priorities; it uses the QOS scheduling mechanism provided by IEEE802.16 and the resource reservation mechanism on the metropolitan area network Guarantee the quality of service requirements of grade services; use base stations and routers supporting MPLS to provide good QOS support, so that services with high priority and high quality of service requirements are transmitted through Layer 2 label switching, while services with low priority and low quality of service requirements are transmitted through Layer 3 routing and forwarding for transmission.

Description of drawings

Fig. 1 is the system structure diagram of broadband wireless metropolitan area network.

Figure 2 is a model diagram of the broadband wireless metropolitan area network protocol stack.

Fig. 3 is a structural diagram of the protocol stack of the base station.

Fig. 4 is a topological structure diagram of broadband wireless metropolitan area network.

Figure 5 is a flow chart of wireless station initialization.

Fig. 6 is a flowchart of voice communication.

Detailed ways

A method for constructing a broadband wireless metropolitan area network that provides hierarchical services, wherein the initialization process of IEEE802.16 wireless stations entering the network is as follows:

Step S1: establishing a wireless link connection between the wireless station and the base station;

Step S2: the wireless station registers with the broadband wireless metropolitan area network to obtain an IP address;

Step S3: The wireless station performs the configuration required by the network operator, and establishes a relevant pre-connection.

The processing steps of each event in Fig. 5 are as follows: (wireless station initialization flow process)

S5.1: When the wireless station enters the network, by detecting the DCD and DL_MAP messages broadcast by the base station, the synchronization with the downlink (the wireless link from the base station to the wireless station) is obtained;

S5.2: Judging whether to successfully synchronize to the downlink, that is, whether to receive valid DCD and DL_MAP messages continuously, if so, enter S5.3; otherwise, go to S5.1 and try to synchronize to the next downlink;

S5.3: Obtain uplink parameters by detecting UCD and UL_MAP messages broadcast by the base station;

S5.4: Judging whether the uplink parameters have been successfully obtained, that is, whether valid UCD and UL_MAP messages are continuously received, and the parameters in the messages are suitable for the wireless station, if so, enter S5.5; otherwise, go to S5.1, Try to sync to the next downlink;

S5.5: Start the ranging process, interact with the base station through RNG-REQ and RNG-RSP messages, adjust related transmission parameters (such as transmission power), and establish a basic (Basic) connection and primary ( Primary) connection, these two connections are used to transmit (management) control signaling between the wireless station and the base station;

S5.6: Determine whether the parameter adjustment is successfully completed, that is, whether the RNG-RSP message marked as SUCCESS is received, if so, enter S5.7; otherwise, go to S5.1, and try to synchronize to the next downlink;

S5.7: After the ranging is completed, start the basic capability negotiation process, interact with the base station through SBC-REQ and SBC-RSP messages, and coordinate the capability parameter sets supported by both parties;

S5.8: Judging whether the basic capability negotiation is successfully completed, whether the base station enables the support of the basic capability parameter set requested by the wireless station, that is, whether the SBC-RSP message whose status flag is OK is received, if so, enter S5.9; otherwise, Go to S5.1, try to synchronize to the next downlink;

S5.9: Start the authentication and key exchange process, and the authentication server participates in the completion of the process;

S5.10: Judging whether the authentication is passed, if the authentication is passed, go to S5.12; otherwise, go to S5.11;

S5.11: The wireless station has not passed the authentication and is prohibited from entering the network;

S5.12: The wireless station registers with the network, completes the registration process through REG-REQ and REG-RSP message interaction, negotiates the IP version number, and establishes a secondary (Secondary) connection, which is used for transfer between the network and the manageable wireless station management control signaling;

S5.13: Judging whether the registration is successful, that is, judging whether the REG-RSP message whose status flag is OK is received, if so, enter S5.14; otherwise, go to S5.1, and try to synchronize to the next downlink;

S5.14: Start the IP connection establishment process, obtain the IP address, and the registration server participates in the completion of the process;

S5.15: Determine whether the IP address is successfully obtained, if so, register the mapping from the phone number to the current IP address to the registration server, and then enter S5.16; otherwise, go to S5.1, and try to synchronize to the next downlink;

S5.16: Start the time synchronization process and the configuration file acquisition process, and the management server participates in completing the process;

S5.17: Judging whether the synchronization and configuration are successful, that is, whether a response message with a status flag of OK is received, if so, enter S5.18; otherwise, go to S5.1, and try to synchronize to the next downlink;

S5.18: Start the pre-connection establishment process, complete the pre-connection establishment through the exchange of DSA-REQ and DSA-REP messages, and the pre-connection is used to transmit the service flow provided in advance by the network operator;

S5.19: Determine whether the pre-connection is successfully established, if so, the wireless station enters the standby state and waits for user events; otherwise, go to S5.1 and try to synchronize to the next downlink;

A method for constructing a broadband wireless metropolitan area network providing hierarchical services, wherein the voice communication process between IEEE802.16 wireless stations is as follows:

Step S1: The call initiator applies for a control bandwidth for transmitting voice communication signaling;

Step S2: The authenticated wireless station applies for service bandwidth for transmitting voice streams;

Step S3: querying the IP address of the called party, starting the routing and resource reservation process, and establishing a label switching path;

Step S4: The called party passes the authentication and establishes a wireless connection with the access base station;

Step S5: start the call process;

Step S6: the call ends, and the system resources occupied by the call are released.

The processing steps of each event among Fig. 6 are as follows: (voice communication flow process)

S6.1: The wireless station receives the dialing event, classifies the called number (emergency call type, general call type, special call type), and determines the service level and QOS parameters according to the category;

S6.2: Apply for the control bandwidth to the base station, the service level and QOS parameters of the control bandwidth are determined according to the requirements of the voice communication signaling system;

S6.3: The base station receives the bandwidth request, and allocates the required system resources for the wireless station through the scheduling module;

S6.4: The wireless station judges whether to obtain the requested bandwidth, that is, whether a control connection (identified by the connection identifier CID) bound with a specific quality of service has been established, if so, enter S6.5; otherwise, go to S6. twenty one;

S6.5: The wireless station sends an authentication request to the AAA server;

S6.6: After receiving the authentication request, the AAA server queries the service usage rights of the calling party and the called party, and then returns an authentication response to the calling wireless station;

S6.7: The wireless station judges whether the call is authenticated, if so, proceed to S6.8; otherwise, proceed to S6.21;

S6.8: The wireless station applies for service bandwidth to the base station, and the service level and QOS parameters of the service bandwidth are the corresponding parameters determined after classification;

S6.9: After receiving the service bandwidth request, the base station allocates system resources that meet the requirements for the wireless station through the scheduling module;

S6.10: The wireless station judges whether the service bandwidth allocation is successful, that is, whether a service connection bound to a specific service quality is established, and if so, enters S6.11; otherwise, proceeds to S6.21;

S6.11: The wireless station initiates a call request signaling to the called party;

S6.12: After receiving the call request signaling, the base station queries the registration server for the current IP address of the called number;

S6.13: The registration server searches for the IP address corresponding to the called number, and then returns the destination IP address to the access base station of the calling party;

S6.14: After the base station receives the response message containing the destination IP address, it starts the process of route search and resource reservation, and establishes the connection between the ingress base station (the access base station of the calling party) and the egress base station (the access base station of the called party). Label switching path between, and establishes the mapping of service connection CID and label switching path;

S6.15: The network judges whether resource reservation and label switching path establishment are successful, if so, go to S6.16; otherwise, go to S6.21;

S6.16: The ingress base station forwards the call request signaling to the egress base station, and the egress base station notifies the called party that a call request is coming and requires the called party to pass the authentication to complete the subsequent call process;

S6.17: After the called party passes the authentication and obtains the required bandwidth, establish the mapping between the service CID and the label switching path; in this way, a Layer 2 switching path is established between the calling party and the called party, and the voice flow will be transmitted on this path;

S6.18: The egress base station sends a ringback tone to the calling party, and the called party initiates a response;

S6.19: After the calling party hears that the called party picks up the phone, the call starts, and the AAA server starts charging for the call;

S6.20: After the call ends, the network releases the system resources (including wireless resources and wired resources) allocated for this call, and then enters the standby state, waiting for the arrival of the user's next event;

S6.21: Since the normal call connection and resource allocation process has not been completed, the call fails.

Claims (6)

1. A broadband wireless metropolitan area network construction method that provides graded services is characterized in that the method uses a broadband wireless metropolitan area network system structure based on the IEEE802.16 protocol, a broadband wireless metropolitan area network protocol stack model, and a broadband wireless metropolitan area network Network base station protocol stack structure and metropolitan area network topology structure, adding interfaces between base stations on IEEE802.16 base stations to expand the wireless coverage area of metropolitan area networks; On the metropolitan area network, the resource reservation protocol is used to ensure the service quality requested by the business, and the MPLS protocol is used to establish a layer-2 switching path to provide support for high-level and high-QOS-required services; Utilize four different service types provided by IEEE802.16: unsolicited grant service UGS, real-time polling service rtPS, non-real-time polling service nrtPS and best-effort service BE to realize hierarchical services, and use layer 2 switching to ensure voice call quality; Described broadband wireless metropolitan area network system structure is made of wireless network, wired network and PSTN, ISDN, GSM and 3G voice communication network, and wherein wireless network is made up of IEEE802.16 wireless station and IEEE802.16 base station system; The broadband wireless metropolitan area network protocol stack model includes a wireless station protocol stack, a base station protocol stack, a wired network protocol stack and their mutual connections; The protocol stack structure of the broadband wireless metropolitan area network base station is divided into four layers: the physical layer of the base station supports OFDMA defined by IEEE802.16PHY and the single-carrier SC mode and IEEE802.3PHY; the data link layer of the base station supports IEEE802. 16MAC, IEEE802.3MAC and IETF PPP protocols; the base station network layer supports MPLS protocol, IP, IPv6 protocol and wireless resource management protocol; above the network layer, the base station supports TCP/UDP transport layer protocol and OSPF routing protocol, and supports label distribution LDP protocol, resource reservation RSVP-TE protocol, mobile management signaling system, call management signaling system, network maintenance signaling system and application layer network protocol. 2. The broadband wireless metropolitan area network construction method that provides graded service according to claim 1, is characterized in that, described IEEE802.16 base station system comprises base station and switching center, adopts IEEE802. The physical layer OFDMA mode defined in 16 and the media access control layer IEEE 802.16MAC protocol are used for wireless connection, and the base station system and the base station system are wirelessly connected through the switching center using the physical layer single-carrier SC mode and directional antenna defined by IEEE802.16. The Ethernet interface defined by IEEE802.3 is used for wired connection between the base station and the access router, and the voice stream between the wireless station and the wireless station only passes through a series of wirelessly connected base stations without going through the wired network; the wired network is composed of The traditional IP network is composed of functional units including access center, registration center, device marker, authentication center, management center and billing center. The access center uses MPLS routers, registration center, device marker, authentication center , management center and billing center use servers based on IP protocol, and optical fibers are used to connect wired network functional units. 3. the broadband wireless metropolitan area network construction method that provides graded service according to claim 1, is characterized in that, In the physical layer of the base station, the interfaces between the wireless station and the base station all adopt the physical layer OFDMA protocol defined by IEEE802.16, and the interfaces between the base station and the base station all adopt the physical layer single-carrier SC protocol defined by IEEE802.16. The interface of wired network interconnection adopts the Ethernet physical layer protocol defined by IEEE802.3; In the data link layer of the base station, the interface between the wireless station and the base station adopts the media access control MAC protocol defined by IEEE802.16, the interface between the base station and the base station adopts the PPP protocol defined by IETF, and the base station and the wired network are interconnected The interface adopts the Ethernet MAC protocol defined by IEEE802.3; The network layer of the base station includes a radio resource management sublayer and an IP sublayer, the radio resource management sublayer manages the wireless resources of the IEEE802.16 access part, including power control, channel allocation and user authentication, and the IP sublayer controls the Internet Protocol Processing, including IP route establishment, MPLS label switching path establishment, route lookup and data forwarding; The above three layers are divided into mobile management sub-layer, call management sub-layer and network maintenance sub-layer. The mobile management sub-layer supports and manages the mobile characteristics of wireless stations, including internal handover and handover. Communication support and management, including call connection, quality of service request, resource application and release, and the network maintenance sublayer provides support for remote control and maintenance of the entire wireless metropolitan area network. 4. The method for constructing a broadband wireless metropolitan area network providing hierarchical services according to claim 1, wherein said mobile management signaling system manages work related to terminal mobility, including processing data from a mobile terminal home agent, when a new When the user moves and joins the base station, the mobile management system commands the specific service convergence sublayer CS convergence sublayer of the IEEE802.16 MAC layer to establish a new connection, and provides corresponding QOS parameters to participate in scheduling. When the user leaves, The mobile management system notifies the radio resource management system to take back the connection and system resources belonging to the mobile terminal; the call management signaling system sends and processes various voice communication signaling messages, realizes normal connection and mobile switching of voice communication, and passes wireless resource The management system realizes reasonable resource reservation to ensure the service quality of calls; the network management signaling system provides communication functions required for network operation management, security management, operation and performance management, system change control, system maintenance and fault recovery. 5. The broadband wireless metropolitan area network construction method that provides graded service according to claim 1, wherein the wireless station voice communication process is as follows: Step S1: The call initiator applies for a control bandwidth for transmitting voice communication signaling; Step S2: The authenticated wireless station applies for service bandwidth for transmitting voice streams; Step S3: querying the IP address of the called party, starting the routing and resource reservation process, and establishing a label switching path; Step S4: The called party passes the authentication and establishes a wireless connection with the access base station; Step S5: start the call process; Step S6: the call ends, and the system resources occupied by the call are released. 6. The broadband wireless metropolitan area network construction method that provides graded service according to claim 5, It is characterized in that the specific steps of the voice communication process are as follows: S6.1: The wireless station receives the dialing event, and classifies the called number: emergency call, general call, and special call, and determines the service level and QOS parameters according to the category; S6.2: Apply for the control bandwidth to the base station, the service level and QOS parameters of the control bandwidth are determined according to the requirements of the voice communication signaling system; S6.3: The base station receives the bandwidth request, and allocates the required system resources for the wireless station through the scheduling module; S6.4: The wireless station judges whether to obtain the requested bandwidth, that is, whether to establish a control connection bound to a specific quality of service, the control connection is identified by the connection identifier CID, if so, enter S6.5; otherwise, go to S6.21; S6.5: The wireless station sends an authentication request to the authentication authorization accounting AAA server; S6.6: After receiving the authentication request, the AAA server queries the service usage rights of the calling party and the called party, and then returns an authentication response to the calling wireless station; S6.7: The wireless station judges whether the call is authenticated, if so, proceed to S6.8; otherwise, proceed to S6.21; S6.8: The wireless station applies for service bandwidth to the base station, and the service level and QOS parameters of the service bandwidth are the corresponding parameters determined after classification; S6.9: After receiving the service bandwidth request, the base station allocates system resources that meet the requirements for the wireless station through the scheduling module; S6.10: The wireless station judges whether the service bandwidth allocation is successful, that is, whether a service connection bound to a specific service quality is established, and if so, enters S6.11; otherwise, proceeds to S6.21; S6.11: The wireless station initiates a call request signaling to the called party; S6.12: After receiving the call request signaling, the base station queries the registration server for the current IP address of the called number; S6.13: The registration server searches for the IP address corresponding to the called number, and then returns the destination IP address to the access base station of the calling party; S6.14: After receiving the response message containing the destination IP address, the base station starts the route search and resource reservation process, establishes the label switching path between the ingress base station and the egress base station, and establishes the mapping between the service connection CID and the label switching path, The entry base station here refers to the access base station of the calling party, and the exit base station refers to the access base station of the called party; S6.15: The network judges whether resource reservation and label switching path establishment are successful, if so, go to S6.16; otherwise, go to S6.21; S6.16: The ingress base station forwards the call request signaling to the egress base station, and the egress base station notifies the called party that a call request is coming and requires the called party to pass the authentication to complete the subsequent call process; S6.17: After the called party passes the authentication and obtains the required bandwidth, the mapping between the service CID and the label switching path is established. In this way, a Layer 2 switching path is established between the calling party and the called party, and the voice flow will be transmitted on this path; S6.18: The egress base station sends a ringback tone to the calling party, and the called party initiates a response; S6.19: After the calling party hears that the called party picks up the phone, the call starts, and the AAA server starts charging for the call; S6.20: After the call ends, the network releases the system resources allocated for this call, including wireless resources and wired resources, and then enters the standby state, waiting for the arrival of the user's next event; S6.21: Since the normal call connection and resource allocation process has not been completed, the call fails.

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