CN1538778A - A method for monitoring packet services based on mobile phone numbers - Google Patents

Abstract

The invention discloses a method for monitoring a packet service according to a mobile phone number. The method pre-adds the IP address of the user access packet data service node (PDSN) in the device (AAA) for authentication, authentication, and accounting in the packet service. The address (PDSN Address), the IP address of the monitoring system (ADMF Address), and the unique identification (Tap ID) of this monitoring are three attributes. Using these three attributes and according to the mobile phone number of the user, the monitoring system passes the proxy AAA (BAAA) ) Complete the setting of the target user on HAAA. When the user accesses the PDSN, the monitoring system establishes a monitoring connection with the PDSN that the user accesses according to the target user setting on the HAAA, and transmits the monitoring service flow, thereby realizing monitoring .

Description

A method for monitoring packet services based on mobile phone numbers

technical field

The invention relates to the technical field of mobile communication security, in particular to a method for legally intercepting packet services according to a mobile phone number (Mobile Directory Number, MDN).

Background technique

At present, all countries in the world have put forward higher requirements for national security, and each country has put forward the requirements for legal interception of telecommunications equipment. China has successively formulated legal interception interface specifications for fixed network and Global System for Mobile Phones (GSM) communications. For the increasingly widely used packet services, it is also necessary to formulate legal interception methods. The packet service refers to the packet data service in the telecommunication network system. In the code division multiple access 2000 (CDMA2000) system, this kind of service is realized through PDSN and AAA server combined with other telecommunication equipment.

In the existing CDMA2000 system, the target user terminal (MS) communicates through the base station subsystem (BBS), and each BBS communicates with the packet data service node (PDSN) on it, and authenticates the packet service of the CDMA2000 system through the node For each user, the AAA where the packet service account is opened is called the local AAA (Home AAA, HAAA). In this CDMA2000 system, HAAA is just a simple server that authenticates and responds according to the authentication request, or records accounting and responds according to the charging request. The HAAA does not have the function of legally intercepting the required information, nor Functionality that triggers lawful interception. In addition, in the prior art, a network structure for CDMA2000 system monitoring has also been proposed, but no specific implementation scheme has been proposed.

With the rapid growth of data services and the needs of national security, it is necessary to formulate a complete solution for legally intercepting CDMA2000.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for monitoring packet services according to mobile phone numbers. When this method is applied to CDMA2000, by adding attributes and extending functions to the HAAA equipment in the CDMA2000 packet network, the purpose of legal interception according to the mobile phone number is achieved.

The present invention is a method for monitoring packet services according to the mobile phone number. The IP address (PDSN Address), the IP address (ADMF Address) of the monitoring system, the unique identification (Tap ID) of this monitoring three attributes, the method comprises the following steps:

A, the monitoring system sends the target user setting message to the agent AAA (BAAA) within the monitoring range, which contains the mobile phone number (MDN), valid Tap ID and ADMFAddress of the target user in the message, and BAAA receives the message, according to MDN analyzes and obtains the AAA (HAAA, Home AAA) address where the target user opens an account, and transmits the MDN, Tap ID and ADMF Address to the HAAA;

B. HAAA finds the corresponding International Mobile Subscriber Identity (IMSI) according to the MDN, and HAAA sets the Tap ID and ADMF Address attribute value of the user corresponding to the IMSI as the Tap ID and ADMF Address attribute in the target user setting message on itself value, and then reply the target user setting reply message to the monitoring system, the message at least includes Tap ID;

C. The monitoring system judges whether the target user setting response message includes a valid PDSN Address, if yes, then execute step D, otherwise, the monitoring system waits until the target user accesses the PDSN, HAAA authenticates the user and records the current connection The PDSN Address of the incoming PDSN, HAAA sends a message including the PDSN Address to the monitoring system according to the AMDF Address, and the monitoring system triggers after receiving the message;

D. The monitoring system judges whether the received Tap ID is valid. If not, the monitoring process ends. Otherwise, according to the PDSN Address of the target user, the monitoring system sends a monitoring request to the PDSN currently accessed by the target user. The request includes Tap ID, monitoring requirements, the IP address and port number of the delivery function entity 2 (DF2) in the monitoring system, the IP address and port number of the delivery function entity 3 (DF3) in the monitoring system, and the PDSN is based on the IP addresses of DF2 and DF3 Address and port number, report business-related events to the monitoring system, and send connection establishment requests;

E. The monitoring system sends a connection establishment request response message to the PDSN, and the PDSN starts to transmit the monitoring service flow with the monitoring system.

Wherein, the method further includes if the user accesses the network, then HAAA saves the valid address of the PDSN currently accessed by the user in itself according to the user ID; if the user leaves the network, then HAAA sets the user's PDSN address as invalid according to the user ID value.

Wherein, in step B, the monitoring system judges whether to receive the effective address of the PDSN accessed by the target user including:

The monitoring system judges whether the received PDSN address field is 0 or empty, if yes, the PDSN address is invalid; otherwise, the PDSN address field is valid.

Wherein, the monitoring system judges whether the Tap ID received is valid for judging whether the Tap ID is 0 or empty, and if so, the Tap ID is invalid; otherwise, it is valid.

Wherein, in step D, the method further includes: the PDSN responds to the monitoring system with the current service status of the user.

Wherein, in step E, the PDSN starts to transmit the interception service flow with the interception system includes: transmitting the interception service flow in the form of Generic Routing Encapsulation (GRE).

Wherein, the method further includes:

If the user switches across PDSNs and the user accesses a new PDSN, the steps C, D and E are executed in sequence. When the monitoring system establishes a monitoring connection with the new PDSN, the monitoring system cancels the monitoring on the original PDSN.

Wherein, if the monitoring system cancels the monitoring of the target user, the method further includes:

The monitoring system sends a target user cancellation message to BAAA. After receiving the message, BAAA generates an access request message and sends it to HAAA. Find the bound IMSI, set the Tap ID of the user corresponding to the IMSI to 0 locally, and then return the target user cancellation response message to the monitoring system.

Wherein, the packet service is code division multiple access (CDMA) 2000 system, CDMA 1X system, CDMA2000 1X enhanced version (CDMA2000 1X EV-DO, HRPD) system used only for data transmission, CDMA2000 system used for data and voice transmission Packet service of 1X enhanced version (CDMA2000 1XEV-DV) system and wireless local loop (WLL) system.

It can be seen that this method realizes the monitoring of the packet network by increasing the radius attribute of HAAA, and this method has the following advantages:

1. It solves the problems caused by the mobility of monitoring objects;

2. It realizes halfway monitoring when the monitoring object has started group business;

3. Realized the discovery and monitoring of monitoring objects according to MDN;

4. Solved the problem of roaming monitoring;

In short, by adding the radius attribute of HAAA, this method realizes the function of monitoring the target user under the premise of making minimal changes to the device. This method can be actually applied to various networks using AAA and PDSN. The scope of application broad and has made useful contributions to national security issues.

Description of drawings

Figure 1 is a group monitoring network diagram of a CDMA2000 system.

FIG. 2 is a sequence diagram of implementing monitoring when the user has already connected to the packet network when the monitoring system performs user target setting in Embodiment 1. FIG.

FIG. 3 is a sequence diagram of implementing monitoring when the user has not yet accessed the packet network when the monitoring system performs user target setting in Embodiment 1. FIG.

Fig. 4 is a sequence diagram of canceling the monitoring of the PDSN by the monitoring system in Embodiment 1.

FIG. 5 is a sequence diagram of canceling a target user by the monitoring system in Embodiment 1. FIG.

Detailed ways

The invention is a method for monitoring grouping services according to mobile phone numbers. In the method, the function of monitoring target users based on MDN is realized by adding a radius attribute to HAAA and expanding HAAA functions. In this method, the monitoring system uses the newly added radius attribute to complete the target user setting on the HAAA, and the HAAA uses the newly added radius attribute to notify the monitoring system of the PDSN address that the target user accesses, thereby establishing a connection between the monitoring system and the PDSN , to transmit the monitoring service flow, so as to realize the monitoring.

The present invention will be described in detail below with reference to the accompanying drawings.

Referring to the network diagram of the CDMA2000 interception system shown in Figure 1, the interception system includes a legal interception access functional entity (LIAF) and an interception center (LEA), wherein the LEA is a functional entity that collects and processes the interception results, and the LIAF specifically includes management functions Entity (ADMF), delivery function entity 2 (DF2) and delivery function entity 3 (DF3), among them, ADMF completes the control and management function of monitoring activities, DF2 completes the function of receiving and distributing packet service-related events, and DF3 completes the reception and distribution Function to group business content. The LIAF is connected to a proxy AAA (BAAA) through an interface. The BAAA is a logical entity, representing an AAA connected to the LIAF, and in the embodiment of the present invention, it is any AAA in the monitoring area. In other embodiments, if the operator does not open the AAA interface due to security and other reasons, BAAA can also be a proxy RADIUS server or proxy RADIUS gateway provided by the operator on the external network with routing to HAAA according to the MDN, and the BAAA and the operator's network HAAA to communicate

The present invention expands their functions by pre-adding the radius attributes on the HAAA and BAAA shown in FIG. 1 , thereby assisting the monitoring system to complete the monitoring work. Specifically, the following three attributes are added, namely:

PDSN Address, indicating the IP address of the PDSN that the user is accessing;

ADMF Address, indicating the IP address of the monitoring system, wherein ADMF is a functional entity that completes the control and management functions of monitoring activities in the monitoring system;

Tap ID, the unique identifier for this monitoring. These three new attributes meet the radius standard, and the specific content can be set according to the standard. The following provides the content of these three attributes in the embodiment of the present invention:

PDSN Address: the IP address of the PDSN that the user is accessing

Type: 26

Length=12

Vendor ID: 5535

Vendor-Type=xxx

Vendor-Length=6

Vendor-Value＝4 octet IP address

ADMF Address: IP address of the listening system

Type: 26

Length=12

Vendor ID: 5535

Vendor-Type=xxx

Vendor-Length=6

Vendor-Value＝4 octet IP address

Tap ID: the unique identification of this monitoring

Type: 26

Length=16

Vendor ID: 5535

Vendor-Type=xxx

Vendor-Length=10

Vendor-Value=Tap ID

These three new attributes meet the radius standard, and the attribute content is determined according to the standard.

When a user accesses a packet network, he will access a PDSN. In the following description, the PDSN to which a user is connected when accessing a packet network is called a serving PDSN.

When a user accesses a packet network, the user accesses a service PDSN, and uses the service PDSN to perform authentication on the HAAA. If the authentication passes, the HAAA records the user's current access service PDSN on the HAAA according to the user identifier. When the user terminates the packet service, the HAAA sets the user's PDSN address to an invalid value according to the user ID.

Considering the different relationships between interception target users and packet networks, the interception method of the present invention will be discussed in the following.

1. When the monitoring system sets the target user, the user has already connected to the packet network:

See Figure 2. At this point, monitoring requires the following steps:

Step 2.1: The monitoring system sends a target user setting message to BAAA, with Tap ID and ADMF Address attributes and a mobile phone number (MDN) in the setting message, where the Tap ID is the unique identifier for this monitoring, and each monitoring Tap The ID takes different values, and when the Tap ID is greater than 0, it means that the target user needs to monitor. In the embodiment of the present invention, the Tap ID takes a value of 1;

Step 2.2: The BAAA receives the target user setting message, analyzes the MDN, obtains the HAAA corresponding to the MDN, generates an access request (access request) message without a user password, and uses this message to set the target user setting message. Tap ID and ADMF Address are passed to the HAAA;

Step 2.3: HAAA receives the access request message and judges that the Tap ID in the message is greater than 0, indicating that this is a target user setting message and does not need to authenticate the user. HAAA searches according to the MDN in the access request message To the International Mobile Subscriber Identity (IMSI) bound to the MDN, complete the following operations locally according to the IMSI:

(1) set the Tap ID attribute value of the target user to the Tap ID attribute value in the access request message;

(2) the ADMF Address attribute value of setting target user is the ADMFAddress attribute value in the access request message;

(3) Send the target user setting response message to the monitoring system, wherein, because the target user has accessed the packet network, in addition to including the Tap ID of this monitoring, the message further includes a newly added attribute PDSN Address , this attribute is the service PDSN address accessed by the target user;

The above steps complete the setting of the monitoring system for the target user;

Step 2.4: The monitoring system sends a monitoring request to the service PDSN according to the service PDSN Address in the response message set by the target user, where the monitoring request includes the monitoring Tap ID of this monitoring, monitoring requirements including the monitoring method and monitoring content , the IP addresses and port numbers of DF2 and DF3, wherein DF2 is a functional entity in the monitoring system that realizes the function of receiving and distributing business-related events, and DF3 is a functional entity in the monitoring system that completes receiving and distributing business content;

Step 2.5: The serving PDSN receives the monitoring request, sends a monitoring request response message to the monitoring system, and informs the monitoring system that the serving PDSN accepts the monitoring request, wherein the user data service status information may be further included in the monitoring request response message, as Inform the listening system that the serving PDSN is active or dormant;

Step 2.6: The serving PDSN reports business-related events to DF2 according to the DF2 address and port number in the monitoring request; and the serving PDSN sends a connection establishment request to DF3 in the monitoring system according to the DF3 address and port number in the monitoring request, and starts to establish services connect;

Step 2.7: The monitoring system receives the connection establishment request, sends a connection establishment request response message to the serving PDSN, the serving PDSN receives the message, and starts to transmit the service flow with the monitoring system to realize the monitoring of the monitoring system. In the example, the monitoring service flow adopts the form of Generic Routing Encapsulation (GRE), and the key field of the GRE header is set as Tap ID; other encapsulation forms can also be used to meet the monitoring service requirements.

2. When the monitoring system sets the target user, the target user has not yet connected to the packet network:

See Figure 3. At this point, monitoring requires the following steps:

Step 3.1: The monitoring system sends a target user setting message to BAAA, which includes the Tap ID and ADMF Address attributes and MDN0 greater than 0 for this monitoring;

Step 3.2: The BAAA receives the target user setting message, analyzes the MDN, obtains the HAAA corresponding to the MDN, generates an access request (access request) message without a user password, and uses this message to set the target user setting message. Tap ID and ADMF Address are passed to the HAAA;

Step 3.3: HAAA receives the user access request message, and judges according to the attribute that the Tap ID in the message is greater than 0 that this is a user setting message. There is no need to authenticate the user, and HAAA completes the following locally:

(1) The Tap ID attribute value of the target user is set as the Tap ID attribute value in the user access request message;

(2) the ADMF Address attribute value of setting target user is the ADMF Address attribute value in the user access request message;

(3) Reply an access request response message to the monitoring system, wherein, since the target user has not yet accessed the packet network, there is no PDSN address or the PDSN attribute value is 0 in the access request response message. In the embodiment of the present invention, this message The value of PDSN Address in is 0;

Step 3.4: The monitoring system receives the target user setting response message, and judges that there is no PDSN address field in the message or the value of the address field is 0. The monitoring system does not take any action on the monitoring interface according to the judgment result, and waits for the user to access and then trigger monitoring;

Step 3.5: When the user accesses the network through dial-up, the serving PDSN generates an access request (accessrequest), and sends the request to HAAA;

Step 3.6: HAAA receives the access request message, judges that there is no Tap ID attribute in the access request message, and obtains that the message is a common access request message, and HAAA proceeds as follows:

(1) At first, the user is authenticated, and if the authentication is passed, the PDSN address in the request message is recorded;

(2) Obtain the IMSI of the user according to the MDN search of the user, and obtain the user in the listening list according to the IMSI search;

(3) Send an access request response to the serving PDSN: access accept or access reject, the embodiment of the present invention is access accept, since the attribute value of the user Tap ID in the HAAA listening list is greater than 0, the access request response message includes Tap ID attribute and ADMF Address, their attribute values are the corresponding attribute values of the user in HAAA;

Step 3.7: The serving PDSN receives the access request response message, judges that the message includes a Tap ID attribute field greater than 0, and sends a monitoring trigger message including the Tap ID to the monitoring system according to the ADMF Address in the message;

Step 3.8: The monitoring system receives the monitoring trigger message, judges that the Tap ID in the message is valid, and sends a monitoring trigger response message to the serving PDSN, wherein the monitoring trigger response message includes monitoring requirements such as monitoring mode, monitoring content, and DF2 IP address and port number, IP address and port number of DF3, Tap ID;

Steps 3.9 to 3.10: The serving PDSN receives the monitoring trigger response message, and reports business-related events to DF2 according to the address and port number of DF2 in the message; at the same time, the serving PDSN reports to the monitoring The system sends a connection establishment request, the monitoring system receives the request and responds to the connection establishment request response, and starts to establish a service connection with the serving PDSN. Wherein, in the present embodiment, the monitoring service flow adopts the form of general routing encapsulation (GRE), wherein the key field of the GRE header is set to Tap ID; other encapsulation forms can also be used to meet the monitoring service requirements.

3. When the user performs cross-PDSN handover:

When a user performs cross-PDSN handover, the user switches to a new PDSN. The process is the same as when the monitoring system sets the target user and the target user has not yet accessed the packet network. At the same time, the user also needs to perform Monitor cancellation, as shown in Figure 4, the specific process includes:

The ADMF in the monitoring system sends a monitoring cancellation message to the original service PDSN, and the original serving PDSN cancels the setting of the target user accordingly, and then sends a monitoring cancellation response message to the ADMF in the monitoring system;

In the embodiment of the present invention, when the monitoring system intends to cancel the monitoring of the target user, as shown in Figure 5, the following steps are required:

The ADMF in the monitoring system sends a target user cancellation message to BAAA, with a Tap ID of 0 in the message; BAAA receives the message, generates a user access request (access request) message without a user password, and Set the Tap ID value in the access request message to 0, and BAAA sends the user access request message to HAAA; HAAA receives the access request message and judges that the Tap ID attribute value in the message is 0, indicating that the message is The target user cancels the message, does not authenticate the user, and performs the following operations: Find the IMSI bound to the user according to the MDN of the user, set the tap ID attribute value of the monitored user to 0 according to the IMSI, and send an access request to the monitoring system Response (access accept) message; the monitoring system judges that the target user has successfully canceled according to the content in the access request response message, and does not take any action on the interface;

The problem of roaming monitoring can be realized by monitoring the target user when the user switches across PDSNs. When the target user accesses the packet network from any PDSN within the monitoring range, timely and accurate monitoring can still be realized.

In the embodiment of the present invention, when the user terminates the packet service, according to the CDMA network packet protocol, the PDSN generates a charging request (accounting stop) message, and sets the sessioncontinue field in the message to 0, sends it to HAAA, and HAAA receives it This message sets the PDSN Address attribute value of the user on the HAAA to 0; and, for the monitored user, the monitoring system releases the monitoring service connection with the serving PDSN for the user.

In the embodiment of the present invention, the message transmission between each PDSN and HAAA can be through a centralized device that implements the above-mentioned newly added radius attribute and monitoring auxiliary function, and through this device, the normal authentication request and calculation on the PDSN The fee request is forwarded to HAAA. This can be achieved without modification to the HAAA.

The present invention can also be applied in CDMA2000, CDMA 1x, EV-DO, EV-DV, WLL system, and its application method is consistent with the steps described in the above embodiments, and those skilled in the art can realize without creative work, therefore, be applied to The monitoring method of the present invention of the above-mentioned system should be within the protection scope of the present invention. Likewise, the present invention can also be applied to the system using AAA combined with PDSN, and the specific implementation steps are the same as the above-mentioned embodiment.

It can be seen that, by adding radius attributes on HAAA, the present invention enables the monitoring system to use these attributes to set target users on HAAA. Once a target user accesses a PDSN within the monitoring range, the target user is set according to the target user on HAAA. The PDSN establishes a connection with the monitoring system, transmits the monitoring service flow, and realizes the monitoring. This method realizes the monitoring of the packet network, and solves the following monitoring problems well, namely:

For the problem of roaming monitoring, for the monitoring object to access the packet network from any PDSN within the monitoring range, the present invention can trigger the monitoring system through HAAA to realize monitoring;

For the problem of pre-monitoring, after the monitoring system issues a monitoring command, the monitored object accesses the packet network, the present invention can realize monitoring by using HAAA to trigger the monitoring system when the user accesses the network;

For the problem of halfway monitoring, for the situation that the monitored object has already connected to the packet network before the monitoring system sends a monitoring command, the present invention can trigger the monitoring system through HAAA to realize the monitoring of the object;

The invention only needs to make minor changes to the existing equipment, is simple and efficient to implement, and has good application prospects.

Claims (9)

1, a kind of method of carrying out the Packet Service monitoring according to Mobile Directory Number, it is characterized in that, increase the IP address (PDSN Address) of user's accessing group data service node (PDSN), the IP address (ADMF Address) of monitoring system, three attributes of unique identification (Tap ID) of this monitoring in advance in the equipment of checking in Packet Service, authentication, charging (AAA), this method may further comprise the steps:

A, the monitoring system AAA (BAAA) that acts on behalf of in the monitoring scope sends targeted customer's setup message, have targeted customer's Mobile Directory Number (MDN), effective Tap ID and ADMFAddress in this message, BAAA receives this message, analyze according to MDN and to obtain the open an account AAA (HAAA at place of targeted customer, Home AAA) address, and MDN, Tap ID and ADMF Address be sent to this HAAA;

B, HAAA find corresponding international mobile subscriber identity (IMSI) according to MDN, HAAA is at the Tap ID and the ADMF Address property value that are set to from the Tap ID of this IMSI respective user on one's body and ADMF Address property value in targeted customer's setup message, reply the targeted customer to monitoring system then and set response message, comprise Tap ID in this message at least;

C, monitoring system judge the targeted customer sets whether comprise effective PDSN Address in the response message, if, execution in step D then, otherwise monitoring system is waited for, is inserted PDSN until this targeted customer, HAAA is to this subscription authentication and write down the PDSN Address of the PDSN of current access, HAAA is according to AMDF Address, and the message that transmission comprises PDSN Address is to monitoring system, and monitoring system obtains triggering after this message;

D, monitoring system judges whether the Tap ID that receives is effective, if not, then finish this snoop procedure, otherwise, PDSN Address according to the targeted customer, monitoring system sends interception request to the PDSN of the current access of targeted customer, comprise Tap ID in this request, listen requirement, the IP address and the port numbers of the propagation function entity 2 (DF2) in the monitoring system, the IP address and the port numbers of the propagation function entity 3 (DF3) in the monitoring system, this PDSN is according to IP address and the port numbers of DF2 and DF3, to monitoring system reporting service dependent event, send and connect the request of foundation;

E, monitoring system send to connect and set up request-reply message to this PDSN, this PDSN begin and monitoring system between carry out the transmission of monitoring service stream.

2, monitor method according to claim 1 is characterized in that this method further comprises if user access network, and then HAAA is kept at self according to user ID with the PDSN effective address of the current access of this user; If user's deviated from network, then HAAA is invalid value according to user ID with this user's PDSN address setting.

3, monitor method according to claim 1 is characterized in that among the step B, and described monitoring system judges whether to receive that the PDSN effective address that the targeted customer inserts comprises:

Monitoring system judges whether the PDSN address field of receiving is 0 or is empty, if then the PDSN address is invalid; Otherwise the PDSN address field is effective.

4, monitor method according to claim 1 is characterized in that described monitoring system judges whether the Tap ID that receives effectively is to judge whether Tap ID is 0 or is empty, if then Tap ID is invalid; Otherwise, effectively.

5, monitor method according to claim 1, it is characterized in that among the step D, this method further comprises: PDSN responds user's current business state to monitoring system.

6, monitor method according to claim 1, it is characterized in that PDSN described in the step e begins and monitoring system between carry out monitoring service stream transmission comprise: monitoring service stream transmits by the form of generic route encapsulation (GRE).

7, monitor method according to claim 1 is characterized in that this method further comprises:

Switch if the user strides PDSN, the user inserts new PDSN, and order is carried out described step C, D and E, and when monitoring system and new PDSN set up monitoring when being connected, monitoring system is cancelled monitoring on former PDSN.

8, monitor method according to claim 1 is characterized in that this method further comprises if the monitoring system cancellation is monitored the targeted customer:

Monitoring system sends the targeted customer to BAAA and cancels message, generation access request message sent to HAAA after BAAA received this message, wherein, comprise in this access request message that attribute is 0 Tap ID, HAAA finds the IMSI of binding according to the MDN in the access request message, the Tap ID that this IMSI respective user is set in this locality is 0, returns the targeted customer to monitoring system then and cancels response message.

9, monitor method according to claim 1, it is characterized in that described Packet Service is code division multiple access (CDMA) 2000 systems, CDMA 1X system, only is used for CDMA2000 1X enhanced edition (CDMA2000 1X EV-DO the uses PD) system of transfer of data, CDMA20001X enhanced edition (the CDMA2000 1X EV-DV) system that is used for data and speech transmissions, the Packet Service of wireless local loop (WLL) system.

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