WO2006012795A1

WO2006012795A1 - A method of crossing-cell handover of cluster mobile station

Info

Publication number: WO2006012795A1
Application number: PCT/CN2005/001178
Authority: WO
Inventors: Qiang Wang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2004-08-02
Filing date: 2005-08-02
Publication date: 2006-02-09
Also published as: NO343611B1; CN100438686C; RO123643B1; NO20071049L; CN1735269A

Abstract

A method of crossing-cell handover of cluster mobile station, comprises: a, after mobile station entering the signal area of target cell, the base station of original cell sends handover request to the base station of target cell; b, the base station of target cell judges itself whether it has assigned forward shared traffic channel for the mobile station of its cell, wherein the mobile station belongs to the same cluster group with the mobile station of the crossing-cell, if yes, then entering step c; if not, entering step d; c, the mobile station accesses the forward shared traffic channel that the base station of target cell assigned for the mobile station of its cell, and ending the flow; d, the base station of target cell assigns forward dedicated traffic channel for the mobile station according to the handover request that the base station of original cell sent to it in step a, then, the mobile station accesses the forward dedicated traffic channel. Using the present invention can utilize the forward shared traffic channel that system assigned for the cluster mobile station, therefore saving the system resource of base station.

Description

Method for handover of cluster mobile station

The present invention relates to the field of soft handover technologies for mobile communications, and in particular, to a method for handover of a trunked mobile station. Background of the invention

With the rapid development of mobile communication technology, as an important branch of mobile communication, the cluster communication technology has also made great progress. Compared with the original cluster communication system, the cluster communication system currently applied has been completely renewed. The early cluster business was a private network operation, providing services for professional users, high operating costs, and limited the development of cluster services. In order to promote the scale application of the cluster system, a new application trend appears in the application of the trunking communication system, which is to provide professional clustering function on the code division multiple access (CDMA) system. The CDMA system can be further divided into wideband codes. Address (WCDMA), CDMA2000, etc. This makes the cluster service largely applicable to the existing hardware resources in the wireless communication system, which reduces the operating cost, and at the same time, the application range of the cluster service is expanded.

The cluster system has two most prominent features. The first feature is: Multiple users belonging to a cluster can communicate at the same time, but at the same time, only one user can speak, and other users can only listen. It reflects the idea of cluster scheduling when the cluster system is initially applied. The second feature is: In a cell, the base station wirelessly communicates with the same group of mobile stations in the cell through a forward shared traffic channel (S-TCH), and each mobile station belonging to the same group passes its own reverse Wireless communication with the base station to a dedicated traffic channel (D-TCH).

When the mobile station in the trunking state moves from the source cell to the target cell, the mobile station's handover operation is initiated, and the mode of the handover is mainly soft handover. The shift During the inter-area movement, the mobile station passes through a region where the source cell signal and the 'target cell signal are jointly covered. When the target cell pilot signal received by the mobile station reaches a certain strength, the pilot station transmits pilot measurement to the source cell base station. The message, the pilot measurement message includes information about the strength of the pilot signal received by the mobile station by the mobile station. After receiving the message, the source cell base station sends a handover request message to the target cell base station. At this time, the soft handover procedure of the mobile station starts. The handover request message includes parameters such as a radio configuration, a long code mask, and a frame offset included in the forward shared service channel allocated by the source cell base station to the cell mobile station.

After receiving the foregoing handover request message, the target cell base station allocates a forward dedicated traffic channel to the mobile station, and returns a handover response message to the source cell base station, where the message includes a forward dedicated service channel allocated by the target cell base station to the mobile station. The channel parameter, after receiving the handover response message, the source cell base station directs the mobile station to access the forward dedicated service channel allocated by the target cell base station according to the channel parameter included in the message.

The above-mentioned target cell base station is a wireless configuration, a long code mask, a frame offset, and the like included in the forward dedicated traffic channel allocated by the mobile station, and a forward shared traffic channel allocated by the source cell base station to the mobile station of the cell. The parameters including the wireless configuration, long code mask, and frame offset must be the same, so that the mobile station can simultaneously receive and process the wireless signals from the source cell base station and the target cell base station for soft handover; otherwise, the mobile station can only The forward shared service channel allocated by the source cell base station to its cell mobile station is hard-switched to the forward dedicated service channel allocated by the target cell base station to the mobile station, that is, the mobile station first releases the channel that maintains a wireless connection with the source cell base station. And accessing the forward dedicated service channel allocated by the target cell base station for a short time.

After the operation, the mobile station communicates with the source cell base station through the forward shared traffic channel allocated by the source cell base station, and communicates with the target cell base station through the forward dedicated traffic channel allocated by the target cell base station. When the mobile station continues to move to the target cell, and the strength of the received pilot signal of the source cell is reduced to a certain extent, the mobile station goes to the network. The network side sends a pilot measurement message, where the mobile station receives information about the strength of the source cell pilot signal in the pilot measurement message. After receiving the message, the source cell base station sends a handover indication message to the mobile station, and after receiving the message, the mobile station releases its wireless connection with the source cell. At this time, the mobile station allocates only the target cell base station. The forward dedicated traffic channel maintains a wireless connection with the target cell site, and the soft handoff procedure of the mobile station ends.

Certainly, after the mobile station enters the common coverage of the source cell signal and the target cell signal, it may not continue to move to the target cell, but moves to the source cell, and finally leaves the signal coverage of the target cell base station; or is neither a source The cell is not another cell mobile of the target cell, and finally leaves the signal coverage of the source cell base station and the target cell base station. In this case, when the mobile station receives the pilot signal of a certain cell and reduces the strength of the pilot signal to a certain extent, it sends a pilot measurement message to the network side, and after receiving the pilot measurement message, the cell releases the interference measurement message. A wireless connection between the mobile stations.

The handover threshold value and the release threshold value are set in the foregoing base station, and the handover threshold value and the release threshold value are sent to the mobile station in a broadcast form or the base station passes the inband signaling after the mobile station handover is completed. Send it to the mobile station. The mobile station compares the received target cell pilot signal strength with the handover threshold value. When the strength of the target cell pilot signal received by the mobile station exceeds the handover threshold value, the mobile station considers that the current received The target cell pilot signal has reached a certain strength, and the pilot signal strength exceeds the handover threshold value means: the pilot signal strength is greater than or equal to the switching threshold value. Similarly, the mobile station also compares the received source cell pilot signal strength with the release threshold value. When the mobile station receives the source cell pilot signal strength below the release threshold value, the mobile station considers the current The strength of the received source cell pilot signal has been reduced to a certain extent.

It can be seen from the above that when the mobile station in the trunking call state is soft-switched to the target cell by the source 'j, the cell in which it is located, the target cell base station accesses the forward dedicated service channel allocated thereto, instead of Forward shared service information allocated by the target cell base station to its cell mobile station Therefore, the target shared cell resource allocated by the target cell base station to its cell mobile station is not fully utilized; as the soft handover mobile station increases, the network side is the mobile station that is undergoing soft handover or soft handover completion. More and more dedicated traffic channels are allocated, which ultimately makes the forward shared traffic channel meaningless; at the same time, the target cell base station allocates different channels for each mobile station that switches to the cell, which makes the target cell base station work. The load is greatly increased, causing a waste of system resources for the target cell base station, and in the case where the soft handover rate is generally high today, the waste of such system resources is more serious. Summary of the invention

In view of this, the main object of the present invention is to provide a method for handover of a trunked mobile station, which can save system resources of a target cell base station.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

A method for handover of a cluster mobile station, the method comprising the following steps:

a. after the mobile station enters the target cell signal coverage, the source cell base station sends a handover request to the target cell base station;

b. The target cell base station determines whether it has allocated a forward shared service channel for the mobile station belonging to the same group as the mobile station in the cell, if it is allocated, proceeds to step c; otherwise, proceeds to step d;

c. the mobile station accesses the target cell, and the base station has allocated a forward shared service channel allocated to the mobile station of the same group as the mobile station in the cell, and ends the process;

d. The target cell base station allocates a forward dedicated traffic channel to the mobile station according to the handover request sent by the source cell base station in step a, and the mobile station accesses the forward dedicated traffic channel.

The method for sending the handover request to the target cell base station by the source cell base station in step a may be:

When the mobile station receives the target cell pilot signal strength exceeds the set handover threshold When the value is received, the mobile station sends a pilot measurement report to the network side, and after receiving the pilot measurement report, the source cell base station sends a handover request to the target cell base station.

The handover request may be: a message including a forward shared traffic channel parameter allocated by the source cell base station to its cell mobile station.

In step C, before the mobile station accesses the forward shared service channel, the following steps may be further included:

Cl. Whether the target cell base station according to the channel parameter included in the handover request sent by the source cell base station is the same as the parameter of the forward shared service channel that has been allocated to the mobile station that belongs to the same group as the mobile station in the cell. Determining whether the forward shared service channel is suitable for the mobile station to perform soft handover, if it is suitable for soft handover, proceeding to step c2; otherwise, directly proceeding to step c3;

C2. The mobile station accesses the forward shared service channel allocated by the target cell base station to its cell mobile station, and ends the process;

C3. The target cell base station allocates a forward dedicated traffic channel to the mobile station according to the channel parameters included in the handover request sent by the source cell base station, and the mobile station accesses the forward dedicated traffic channel.

In step c2, the process of the mobile station accessing the forward shared service channel may be: the target cell base station sends a handover response to the source cell base station, and the source cell base station directs the mobile station to access the forward share according to the handover response. Traffic channel.

The handover response may be: a message including a forward shared traffic channel parameter allocated by a target cell base station to a mobile station of the same group as the mobile station.

In step c3, the process of the mobile station accessing the forward dedicated service channel may be: the target cell base station sends a handover response to the source cell base station, and the source cell base station directs the mobile station to access the forward dedicated according to the handover response. Traffic channel.

In step c3, after the mobile station accesses the forward dedicated service channel, the method may To further include the following operations:

The mobile station re-accesses the forward shared service channel allocated by the target cell base station to its cell mobile station, releases the forward dedicated traffic channel, and releases the radio resource allocated by the source cell base station.

In step c3, after the mobile station accesses the forward shared service channel, the mobile station accesses the forward shared service channel allocated by the target cell base station to its cell mobile station, releases the forward dedicated service channel, and releases the source. The method for the radio resource allocated by the cell base station may include the following steps:

c. When the mobile station receives the source cell pilot signal whose strength is lower than the release threshold value set by itself, the mobile station sends a pilot measurement report to the network side, and after receiving the pilot measurement report, the source cell base station goes to the target. The cell base station sends a handover request;

C32. After receiving the handover request, the target cell base station sends a handover response to the source cell base station, and the source cell base station directs the mobile station to access the forward shared service channel according to the handover response, and releases the mobile station with the mobile station. Wireless connection, and then sending a release indication to the target cell base station;

C33. After receiving the release indication, the target cell base station releases the forward dedicated traffic channel allocated for the mobile station.

In step c32, the handover response may be: a message including a forward shared traffic channel parameter allocated by the target cell base station to its cell mobile station.

In step d, after the mobile station accesses the forward dedicated service channel, the method may further include the following operations:

The mobile station releases the radio resources allocated by the source cell base station for it.

The method for the mobile station to release the radio resource allocated by the source cell base station for the source cell may include the following steps:

Dl. When the mobile station receives the source cell pilot signal strength lower than its own set release When the threshold value is used, the mobile station sends a pilot measurement report to the network side;

D2. After receiving the pilot measurement report, the source cell base station sends a handover indication to the mobile station, and after receiving the indication, the mobile station releases its wireless connection with the source cell.

According to the foregoing technical solution, the method for handover of a trunked mobile station provided by the present invention is compared with the prior art. When the mobile station performs handover, the target cell base station first determines whether it is already in its cell. The mobile station belonging to the same group of the mobile station allocates a forward shared service channel, and if allocated, the mobile station directly accesses the forward shared channel, and if not allocated, allocates a forward dedicated service to the mobile station. The channel, the mobile station, in turn, soft handoffs to the forward dedicated traffic channel.

In the present invention, the mobile station performing the handover can directly access the forward shared channel allocated to the group in the target cell under certain conditions. In this case, the target cell is not required to allocate and use a dedicated forward shared channel for the mobile station. Therefore, the method of the present invention enables the target cell base station to fully utilize the forward shared traffic channel allocated by its cell mobile station, thereby saving system resources of the target cell base station.

In addition, in the present invention, if the target cell base station has allocated a forward shared traffic channel to a mobile station belonging to the same group as the mobile station in the cell, the target cell base station may further determine whether the forward shared service channel is suitable. The mobile station performs soft handover. If applicable, the mobile station directly soft-switches to the forward shared service channel allocated by the target cell base station to the mobile station of the same group as the mobile station in the cell; if not, the mobile station can The forward shared traffic channel is directly accessed through a hard handover in an edge region of the target cell signal coverage. In this way, the reliability of the handover is further ensured. BRIEF DESCRIPTION OF THE DRAWINGS

1 is a flow chart of a handover of a cluster mobile station according to a first preferred embodiment of the present invention; FIG. 2A is a mobile road diagram of a mobile station according to a first preferred embodiment of the present invention; 2B is a diagram showing a channel access state when the mobile station is in the ^pl position according to the first preferred embodiment of the present invention;

2C is a diagram showing a channel access state when the mobile station is in the p2 position according to the first preferred embodiment of the present invention;

2D is a diagram showing a channel access state when the mobile station is in the p3 position according to the first preferred embodiment of the present invention;

2E is a diagram showing a channel access state when the mobile station is at p 44 according to the first preferred embodiment of the present invention;

3 is a flow chart of a handover of a cluster mobile station according to a second preferred embodiment of the present invention; FIG. 4A is a mobile road diagram of a mobile station according to a second preferred embodiment of the present invention;

4B is a diagram showing a channel access state when the mobile station is in the p1 position according to the second preferred embodiment of the present invention;

4C is a diagram showing a channel access state when the mobile station is in the p2 position according to the second preferred embodiment of the present invention;

4D is a diagram showing a channel access state when the mobile station is in the p3 position according to the second preferred embodiment of the present invention;

4E is a diagram showing a channel access state when the mobile station is in the p4 position according to the second preferred embodiment of the present invention;

Figure 4F is a diagram showing the state of channel access when the mobile station is in the p5 position according to the second preferred embodiment of the present invention. Mode for carrying out the invention

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The main idea of the method for handover of a trunking mobile station provided by the present invention is: When a mobile station performs handover, the target cell base station first determines whether it is already in its cell and The mobile station belonging to the same group of the mobile station allocates a forward shared service channel, and if allocated, the mobile station directly accesses the forward shared channel, and if not allocated, allocates a forward dedicated service to the mobile station. The channel, which in turn soft switches to the forward dedicated traffic channel.

The invention will now be described in detail with reference to two preferred embodiments.

First preferred embodiment:

1 is a flow chart of a cluster mobile station handover according to a preferred embodiment of the present invention, which includes the following steps:

Step 100: When the mobile stations belonging to the same group perform cluster communication, multiple mobile stations belonging to the group in each cell respectively access the forward shared service channel allocated by the base station of the cell in which the cell is located, Maintain a wireless connection to the base station. At this time, if a mobile station belonging to the group moves from the current source cell to the adjacent target cell, the mobile station enters a source cell signal and the target cell signal to jointly cover during the mobile process. Area.

When the target cell pilot signal received by the mobile station reaches a certain strength, a pilot measurement message is sent to the source cell base station, where the pilot measurement message includes information about the strength of the target cell pilot signal received by the mobile station. After receiving the message, the source cell base station sends a handover request message to the target cell base station, where the handover request message includes a channel parameter of the forward shared service channel allocated by the source cell base station to the mobile station, where the channel parameter refers to the source cell base station. Parameters such as the wireless configuration, long code mask, and frame offset included in the forward shared traffic channel allocated to its cell mobile station.

Step 101: The target cell base station determines whether it has allocated a forward shared service channel to the mobile station in the same cell that belongs to the same group as the mobile station to be handed over in the cell, and if yes, proceeds to step 104; otherwise, proceeds to step 102.

Step 102: The target cell base station according to the channel parameter included in the received handover request message The number allocates a forward dedicated traffic channel to the mobile station, and returns a handover response message to the source cell base station, the message including channel parameters of the forward dedicated traffic channel allocated by the target cell base station to the mobile station.

Step 103: After receiving the handover response message returned by the target cell base station, the source cell base station directs the mobile station to access the forward dedicated service channel allocated by the target cell base station to the mobile station according to the channel parameter included in the message. When the mobile station continues to move to the target cell, and the strength of the source cell pilot signal is reduced to a certain extent, the mobile station sends a pilot measurement message to the source cell base station, where the pilot measurement message includes the mobile station receiving the target. Information about the pilot signal strength of the cell. After receiving the message, the source cell base station sends a handover indication message to the mobile station. After receiving the message, the mobile station releases its wireless connection with the source cell and ends the process.

In this step, the target cell base station allocates a forward dedicated traffic channel for the mobile station, and the forward shared service channel allocated by the source cell base station currently accessed by the mobile station at the same time has the same wireless configuration, a long code mask, Channel parameters such as frame offset, which enables the mobile station to simultaneously receive and process wireless signals from the source cell base station and the target cell base station.

Step 104: The target cell base station determines, according to the parameters included in the received handover request message, whether the forward shared service channel allocated by the mobile station that belongs to the same group as the mobile station to be handed over in the cell is suitable for the mobile station. The mobile station performs soft handoff, if appropriate, proceeds to step 105; otherwise, proceeds to step 107.

Whether the above is suitable for soft handover, specifically: the channel parameters such as the radio configuration, the long code mask, and the frame offset included in the forward shared service channel allocated by the target cell base station to the mobile station of the cell, and the source cell base station Whether the channel parameters such as the radio configuration, the long code mask, and the frame offset included in the forward shared traffic channel allocated by the mobile station of the cell are the same, and if they are the same, it is considered to be suitable for soft handover; otherwise, it is considered to be unsuitable for soft handover.

Step 105: The target cell base station returns a handover response message to the source cell base station, where the handover The response message includes channel parameters of the forward shared traffic channel allocated by the target cell base station to its cell mobile station. After receiving the handover response message returned by the target cell base station, the source cell base station directs the mobile station to access the forward shared service channel allocated by the target cell base station to its cell mobile station according to the channel parameter included in the handover response message.

Step 106: When the mobile station continues to move to the target cell, and the strength of the source cell pilot signal is reduced to a certain extent, the mobile station sends a pilot measurement message to the network side, where the pilot measurement message includes the mobile station receiving Information about the pilot signal strength to the source cell. After receiving the message, the source cell base station sends a handover indication message to the mobile station, and after receiving the message, the mobile station releases its wireless connection with the source cell, and the mobile station's handover to the end ends.

Step 107: The mobile station hard-switches to the forward shared service channel allocated by the target cell base station to its cell mobile station, and the specific hard handover method is:

The target cell base station returns a handover response message to the source cell base station, the handover response message including channel parameters of the forward shared traffic channel allocated by the target cell base station to its cell mobile station. After receiving the handover response message returned by the target cell base station, the source cell base station releases its wireless connection with the user, and directs the mobile station to access the target cell base station according to the channel parameters included in the handover response message. A forward shared traffic channel allocated by the cell mobile station.

In the above step 107, although the mobile station accesses the forward shared traffic channel allocated by the target cell base station to its cell mobile station through hard handover, in general, the mobile station is currently at the edge of the target cell signal coverage area, so When the mobile station performs a hard handover, it is easy to drop the call because the received target cell signal is not strong enough.

In the following, the mobile station handover method according to this embodiment is further clarified by describing different channel access states of the mobile station in the handover process.

Referring to FIG. 2A, FIG. 2A is a mobile road diagram of a mobile station according to a first preferred embodiment of the present invention. Wherein, the three circles respectively represent the signal coverage of the cell &, the cell b and the cell c, pi To p4 represents the position of the mobile station in different movement processes, and the line segment with arrows represents the movement route of the mobile station. It can be seen that the mobile station has experienced four different processes during the movement. When the mobile station is located at the pi position, the mobile station is only within the signal coverage of the cell a; when the mobile station moves to the p2 position, the mobile station is within the range covered by the signal of the cell a and the b signal of the cell; When the mobile station is in the p3 position, the mobile station is only within the signal coverage of the cell b; when the mobile station moves to the p4 position, the mobile station is within the range covered by the signal of the cell b and the signal of the cell c.

It is assumed that there are mobile stations belonging to the same group as the mobile stations moved from the pi position to the p4 position in the cell a, the cell b, and the cell c, and all the mobile stations described below belong to the same group. When these mobile stations perform trunking communication, the mobile station in cell a accesses the forward shared traffic channel allocated by the cell a base station; the mobile station in cell b accesses the forward shared traffic channel allocated by the cell b base station The mobile station in cell c accesses the forward shared traffic channel allocated by the cell c base station. In addition, the forward shared service channel allocated by the cell b base station is suitable for soft handover by the mobile station in the cell a; and the forward shared service channel allocated by the cell c base station is not suitable for the soft handover by the mobile station in the cell b.

Referring to FIG. 2B, FIG. 2B is a diagram showing a channel access state when the mobile station is in the pi position according to the first preferred embodiment of the present invention. As shown in FIG. 2B, the mobile station is at the pi position, and the solid line segment with the origin at the other end of the arrow represents the forward shared traffic channel allocated by the cell a base station to its cell mobile station. At this time, the mobile station is passing through the channel. The base station maintains a wireless connection; one end of the cell b and the cell c with the arrow and the dotted line segment with the origin at the other end represents the forward shared traffic channel allocated by the cell b base station and the cell c base station for each cell mobile station, and the mobile at this time The station does not access the forward shared traffic channel allocated by the cell b base station or the cell c base station, and the above origin represents the base station. The meanings of the origin and the line segment in each of the following figures are the same as those indicated by the origin and the line segment in the figure.

As can be seen from FIG. 2B, when the mobile station communicates at its current pi position, it passes through small The area a base station maintains a wireless connection with the cell a base station for the forward shared traffic channel allocated by its cell mobile station.

Referring to FIG. 2C, FIG. 2C is a diagram showing a channel access state when the mobile station is in the p2 position according to the first preferred embodiment of the present invention. As shown in FIG. 2C, the mobile station is now in the p2 position. At this time, the mobile station accesses the forward shared traffic channel allocated by the mobile station b base station to its cell mobile station through soft handover, and then the mobile station currently passes the cell a base station. The forward shared traffic channel allocated by the cell mobile station maintains wireless communication with the cell a base station, and also maintains wireless communication with the cell b base station by the forward shared traffic channel allocated by the cell b base station to its cell mobile station.

Referring to FIG. 2D, FIG. 2D is a diagram showing a channel access state when the mobile station is in the p3 position according to the first preferred embodiment of the present invention. As shown in Fig. 2D, the mobile station is now in the p3 position, and when the mobile station receives the strength of the pilot signal of the cell a to a certain extent, it transmits a pilot measurement message to the cell a base station. After receiving the message, the cell a base station sends a handover indication message to the mobile station, and after receiving the message, the mobile station releases its wireless connection with the cell a. Then, the mobile station currently maintains wireless communication with the cell b base station only through the forward shared traffic channel allocated by the cell b base station to its cell mobile station.

Referring to FIG. 2E, FIG. 2E is a diagram showing a channel access state when the mobile station is in the p4 position according to the first preferred embodiment of the present invention. As shown in FIG. 2E, the mobile station is now in the p4 position. At this time, the mobile station accesses the forward shared traffic channel allocated by the mobile station to the cell mobile station through the hard handover, and the cell b base station releases the mobile station. The established wireless connection, the mobile station currently maintains wireless communication with the cell c base station only through the forward shared traffic channel allocated by the cell c base station to its cell mobile station.

Second preferred embodiment:

In order to solve the problem of dropped calls that are easily generated when the mobile station performs hard handover at the edge of the signal coverage area of the target cell, a better mobile station handover method will be listed below.

Referring to FIG. 3, FIG. 3 is a cross-sectional flow of a cluster mobile station according to a second preferred embodiment of the present invention. Cheng Tu. The steps 300 to 306 are completely the same as the steps 100 to 106 in the flow described in FIG. 1, and the description is not repeated here. Hereinafter, starting from step 307 of FIG. 3, the flow of the mobile station handover will be continued.

Steps 307-308: After the target cell base station determines that the mobile station is not suitable for soft handover, it allocates a forward dedicated traffic channel to the mobile station according to the channel parameter included in the received handover request message, and returns the handover to the source cell base station. a response message, the handover response message includes a channel parameter of the forward dedicated traffic channel allocated by the target cell base station to the mobile station, and after receiving the handover response message, the source cell base station directs the mobile station to access the target according to the channel parameter included in the message. The cell base station allocates a forward dedicated traffic channel for the mobile station.

The forward dedicated service channel allocated by the target cell base station to the mobile station, and the forward shared traffic channel allocated by the source cell base station currently accessed by the mobile station, having the same wireless configuration, long code mask, and frame offset Equal channel parameters, which enable the mobile station to simultaneously receive and process wireless signals from the source cell base station and the target cell base station.

Step 309: When the mobile station continues to move to the target cell, so that the strength of the source cell pilot signal is reduced to a certain extent, the mobile station sends a pilot measurement message to the network side, where the pilot measurement message includes the mobile The station receives information about the strength of the pilot signal of the source cell. After receiving the message, the source cell base station sends a handover request message to the target cell base station again. After receiving the handover request message, the target cell base station returns a handover response message to the source cell base station, where the handover response message includes a channel parameter of the forward shared service channel allocated by the target cell base station to its cell mobile station.

After receiving the handover response message, the source base station releases its wireless connection with the user, and according to the channel parameters included in the handover response message, directs the mobile station to access the target cell base station to allocate for its cell mobile station. Forwarding the traffic channel; Thereafter, the source cell base station sends a handover request message to the target cell base station, and after receiving the handover request message, the target cell base station releases the forward dedicated traffic channel allocated for the mobile station. At this time, the mobile station maintains wireless communication with the target cell base station only through the forward shared traffic channel allocated by the target cell base station to its cell mobile station.

Among them, step 309 is actually a hard handover process. In step 309, the source cell base station releases the forward shared traffic channel allocated for the mobile station; the source cell base station directs the mobile station to access the target shared cell base station to allocate a forward shared traffic channel for its cell mobile station; and the target cell The three operations of the base station releasing the forward dedicated traffic channel allocated to the mobile station may be performed sequentially or simultaneously.

In addition, when the user performs a hard handover in step 309, it is already in the target cell signal coverage range, and can receive a relatively strong signal region. The hard handoff operation performed at this time has the same low dropped call rate as the soft handoff in the prior art, which enables the user to maintain good communication continuity throughout the handover process.

Referring to FIG. 4A, FIG. 4A is a mobile road diagram of a mobile station according to a second preferred embodiment of the present invention. Wherein, the three circles respectively represent the signal coverage of the cell &, the cell b and the cell c, and the pi to p5 represent the position of the mobile station in different movement processes, and the line segment with the arrow represents the moving route of the mobile station, visible, moving The station has experienced five different processes on the move. When the mobile station is located at the pi position, the mobile station is only within the signal coverage of the cell a; when the mobile station moves to the p2 position, the mobile station is within the range covered by the signal of the cell a and the b signal of the cell; When the mobile station is in the p3 position, the mobile station is only within the signal coverage of the cell b; when the mobile station moves to the p4 position, the mobile station is within the range covered by the signal of the cell b and the signal of the cell c; When the station is in the p5 position, the mobile station is only within the signal coverage of the cell c.

It is assumed that there are mobile stations belonging to the same group as the mobile stations moved from the pi position to the p5 position in the cell a, the cell b, and the cell c, and all the mobile stations described below belong to The same group. When these mobile stations perform trunking communication, the mobile station in cell a accesses the forward shared traffic channel allocated by the cell a base station; the mobile station in cell b accesses the forward shared traffic channel allocated by the cell b base station The mobile station in cell _c accesses the forward shared traffic channel allocated by the cell _c base station. In addition, the forward shared traffic channel allocated by the cell b base station is suitable for soft handover by the mobile station in the cell a; and the forward shared traffic channel allocated by the cell c base station is not suitable for soft handover by the mobile station in the cell b.

4B to 4D in the present embodiment are completely the same as those in Figs. 2B to 2D in the first embodiment, and are not repeated here. Now, starting from Fig. 4E in this embodiment, the different channel access states of the mobile station during the handover process will be described.

Referring to FIG. 4E, FIG. 4E is a diagram showing a channel access state when the mobile station is in the p4 position according to the second preferred embodiment of the present invention. As shown in FIG. 4E, the mobile station is now in the p4 position. At this time, the cell c base station allocates a forward dedicated traffic channel to the mobile station, and transmits a message including the channel parameter to the cell b base station to make the cell b base station. The mobile station may be directed to access the forward dedicated traffic channel by soft handover according to the received corresponding message; meanwhile, the forward dedicated traffic channel and the cell b base station have a forward shared traffic channel allocated by the cell mobile station thereof. The same wireless configuration, long code mask, frame offset and other channel parameters make soft switching possible.

After the mobile station accesses the forward dedicated traffic channel allocated by the cell c base station through the soft handover, the mobile station maintains wireless communication with the cell b base station in addition to the forward shared traffic channel allocated by the cell b base station to its cell mobile station. The forward dedicated traffic channel assigned to it by the cell c base station is also maintained in wireless communication with the cell c base station.

Referring to FIG. 4F, FIG. 4F is a diagram showing a channel access state when the mobile station is in the p5 position according to the second preferred embodiment of the present invention. As shown in FIG. 4F, the mobile station is now in the p5 position. At this time, the mobile station performs a hard handover in the cell c, and the overall hard handover operation is: the mobile station releases the forward shared service channel allocated by the source cell base station, Drying the target cell base station before it is allocated To the dedicated traffic channel, and access the forward shared traffic channel allocated by the target cell to its cell mobile station.

After the hard handover described above, the mobile station maintains wireless communication with the cell C base station only through the forward shared traffic channel allocated by the cell C base station to its cell mobile station.

The handover threshold value and the release threshold value are set in the base station described in the above two embodiments, and the handover threshold value and the release threshold value are sent to the mobile station in a broadcast form. The mobile station compares the received target cell pilot signal strength with the handover threshold value. When the strength of the target cell pilot signal received by the mobile station exceeds the handover threshold value, the mobile station considers that the current received The target cell pilot signal has reached a certain strength, and the pilot signal strength exceeds the handover threshold value means: the pilot signal strength is greater than or equal to the switching threshold value. Similarly, the mobile station also compares the received source cell pilot signal strength with the release threshold value. When the mobile station receives the source cell pilot signal strength below the release threshold value, the mobile station considers the current The strength of the received source cell pilot signal has been reduced to a certain extent.

In addition, as shown in FIG. 1 and FIG. 3 of the above two embodiments, when the user performs the handover, it is required to determine whether the target cell base station has allocated the forward shared service channel to the mobile station of the same group of the cell; The target cell base station does not allocate a forward shared traffic channel to its cell mobile station, and when the mobile station performs soft handover, the target cell base station allocates a forward dedicated traffic channel to the mobile station according to the prior art soft handover method, and moves. The station also accesses the forward dedicated traffic channel according to the soft handover method of the prior art, and finally releases the radio resource allocated by the source cell base station when the strength of the source cell pilot signal is reduced to a certain extent.

All of the above are the complete process of the mobile station switching from the source cell to the target cell. Of course, after the mobile station enters the common coverage of the source cell signal and the target cell signal, it may not continue to move to the target cell, but to the source. The cell moves and eventually leaves the target cell base station Signal coverage; or moving to another cell that is neither the source cell nor the target cell, and finally leaving the signal coverage of the source cell base station and the target cell base station. In this case, when the mobile station receives the pilot signal of a certain cell and reduces the strength of the pilot signal to a certain extent, it sends a pilot measurement message to the network side, and after receiving the pilot measurement message, the cell releases the interference measurement message. A wireless connection between the mobile stations.

It can be seen from the above that the method for the handover of the trunking mobile station provided by the present invention enables the forward shared traffic channel allocated by the cell base station to its cell mobile station to be fully utilized, thereby saving the system resources of the cell base station.

The above is only the embodiment of the process and method of the present invention, and is not intended to limit the present invention. Any modifications, equivalents, improvements, etc. made within the spirit and principles of the present invention should be included in the present invention. Within the scope of protection.

Claims

Claim

A method for handover of a cluster mobile station, characterized in that the method comprises the following steps:

The method according to claim 1, wherein in the step a, the method for the source cell base station to send a handover request to the target cell base station is:

When the target cell pilot signal strength received by the mobile station exceeds the set handover threshold value, the mobile station sends a pilot measurement report to the network side, and after receiving the pilot measurement report, the source cell base station sends a handover request to the target cell base station. .

The method according to claim 1 or 2, wherein the handover request is: a message including a forward shared service channel parameter allocated by the source cell base station to its cell mobile station.

The method according to claim 3, wherein, in step c, before the mobile station accesses the forward shared service channel, the method further includes the following steps:

Cl. Whether the target cell base station according to the channel parameter included in the handover request sent by the source cell base station to the same group as the mobile station in the cell The parameters of the forward shared service channel allocated by the station are the same, and it is determined whether the forward shared service channel is suitable for the mobile station to perform soft handover, if it is suitable for soft handover, proceed to step c2; otherwise, directly proceed to step c3;

The method according to claim 4, wherein, in step c2, the process of the mobile station accessing the forward shared service channel is:

The target cell base station transmits a handover response to the source cell base station, and the source cell base station directs the mobile station to access the forward shared traffic channel according to the handover response.

The method according to claim 5, wherein the handover response is: including a forward shared service channel allocated by a target cell base station to a mobile station of the same group as the mobile station in the cell. The message of the parameter.

The method according to claim 4, wherein in step c3, the process of the mobile station accessing the forward dedicated service channel is:

The target cell base station transmits a handover response to the source cell base station, and the source cell base station directs the mobile station to access the forward dedicated traffic channel according to the handover response.

The method according to claim 4, wherein, in step c3, after the mobile station accesses the forward dedicated service channel, the method further includes the following operations:

9. The method according to claim 8, wherein in step c3, the mobile station After accessing the forward shared service channel, accessing the forward shared service channel allocated by the target cell base station to its cell mobile station, releasing the forward dedicated traffic channel, and releasing the source cell base station for allocating the same The method of wireless resources includes the following steps:

The method according to claim 9, wherein in step c32, the handover response is: a message including a forward shared service channel parameter allocated by the target cell base station to its cell mobile station.

The method according to claim 1, wherein in step d, after the mobile station accesses the forward dedicated service channel, the method further includes the following operations:

The method according to claim 11, wherein the method for the mobile station to release the radio resource allocated by the source cell base station includes the following steps:

Dl. When the source station pilot signal strength received by the mobile station is lower than the release threshold value set by itself, the mobile station transmits a pilot measurement report to the network side;