CN100415028C - Method for mobile terminal switching between base stations to access target base station - Google Patents

Abstract

The invention discloses a method for a mobile terminal switching between base stations to access a target base station. The method is as follows: the target base station divides a part of the fixedly allocated random access resources as random access resources available to switching users; A mobile terminal that performs handover between the source base station and the target base station accesses the target base station by using random access resources available to the handover user. The present invention provides a part of fixedly allocated random access resources exclusively for switching users, thereby fully ensuring the performance of switching users, greatly improving user switching speed and success rate, and reducing packet loss rate.

Description

Method for mobile terminal switching between base stations to access target base station

technical field

The invention relates to the technical field of mobile communication, in particular to a method for a mobile terminal switching between base stations to access a target base station.

Background technique

Handover is one of the notable features that distinguish mobile communication from fixed communication. When the cell or system used by the user changes, for example, FDD or TDD changes, it is considered that the user has switched.

Usually, if the system has high requirements for synchronization, especially uplink synchronization, then after the user switches to the target cell, in order to avoid interference to other communicating users in the target cell, the service resources in the target cell cannot be directly used. At this time, before the mobile terminal in the handover state interacts with the target base station, it needs to adjust its own uplink transmission power and the timing relationship between itself and the base station. Therefore, when a system that requires high uplink synchronization receives handover users, it must consider the interference to other users. To reduce interference, when a mobile terminal switches to a target base station, it must go through an access process to adjust related parameters.

Generally speaking, there are two types of cell access methods, one is the initial random access process initiated by the original users in the cell to exchange signaling or service data with the base station; the other is switching from other cells The access process initiated by the user to adjust related parameters.

In the following, the TD-SCDMA system is taken as an example to illustrate the method for a mobile terminal switching between base stations to access a target base station in the prior art.

Referring to Figure 1, the specific access process is as follows:

Step 101, the radio network controller (RNC) broadcasts the topology structure of the current network to the mobile terminal through the source base station, and notifies the mobile terminal to measure the signal quality of adjacent cells.

Step 102, after receiving the notification, the mobile terminal measures the signal quality of surrounding cells, and reports the measurement result to the RNC.

Step 103, after the RNC receives the measurement result reported by the mobile terminal, it judges whether the mobile terminal needs to be handed over. If necessary, the source base station notifies the mobile terminal to switch to the target cell of the target base station, and simultaneously notifies the target base station that there is a handover user To access, otherwise jump out of this process.

Step 104, after the target base station receives the notification from the RNC that there is a handover user to access, check whether there is an available uplink synchronization code in the target cell, if so, notify the mobile terminal that the handover can be performed through the source base station, and The notification content also includes related information such as power and timing of the target base station.

Step 105: After the mobile terminal receives the information related to the mobile terminal sent by the target base station, the target base station competes to use the uplink synchronization code for initial uplink synchronization, and then accesses the target base station. At this point, the source base station may disconnect from the mobile terminal.

In step 104, if the target base station has no usable uplink synchronization code, the switching user must compete again until the uplink synchronization code is obtained through competition. It should be noted that in the TD-SCDMA system, the uplink synchronization code is the random access resource. The users who want to access the target base station may include initial random access users, handover users, and the like. Therefore, all mobile terminals that want to access the target base station must compete for random access resources at the same time. Of course, when the system resources are tight, it is very likely that the competition will not succeed once, and repeated competitions are required. And it is also possible that the competition is unsuccessful for a long time, resulting in the inability to access the target base station for a long time, and finally causing packet loss.

To sum up, when the system has relatively high requirements for uplink synchronization, after the mobile terminal switches to the cell of the target base station, in order to avoid or reduce interference to other users, the mobile terminal needs to establish uplink synchronization with the target base station and adjust the timing , transmit power, etc. Therefore, if the service resources of the target base station are in short supply, it may take a period of time for the handover user to successfully access the target base station. This will lead to too long interruption of user service, which will affect the service quality of the handover user, thereby causing the decline of user service satisfaction.

Contents of the invention

In view of this, the object of the present invention is to provide a method for a mobile terminal switched between base stations to access a target base station, to ensure that the switched mobile terminal has access resources available, and to improve the access success rate of switched users.

A method for a mobile terminal switching between base stations to access a target base station provided by the present invention includes:

The target base station divides a part of the fixedly allocated random access resources as the random access resources available to the handover user; the mobile terminal performing handover between the source base station and the target base station uses the random access resources available to the handover user to access target base station.

The access further includes:

B1. The mobile terminal sends a message to the source base station to switch to the target base station; after receiving the message, the source base station sends the mobile terminal capability information and service information to the target base station;

B2. After receiving the capability information and service information of the mobile terminal, the target base station designates random access resources for the mobile terminal;

B3. The target base station forwards the specified access resources and the power and timing information of the local terminal to the mobile terminal through the source base station; the mobile terminal adjusts the transmission power and timing according to the power and timing information sent by the target base station, and uses the specified access resources to access the target base station.

The method further includes: the target base station uses a part of the fixedly allocated random access resources except the random access resources allocated to handover users as the random access resources for the user's initial random access.

Described step B2 further comprises:

B21. The target base station judges whether it has random access resources available to the handover user, and if so, selects one of the random access resources available to the handover user as the access resource of the mobile terminal, and then performs step B3, Otherwise, execute step B22;

B22. Determine whether you still have random access resources available to non-handover users in the random access resources that are fixedly allocated, and if so, select one of them as the access resource of the mobile terminal, and then perform step B3, otherwise , the access failed.

The random access resources available to the handover user are divided from fixedly allocated access resources according to certain rules.

The certain rule is preset according to the spread spectrum codeword, time, frequency, space, or any combination of the four.

The division of the fixedly allocated random access resources is determined according to the proportion of handover users in the target base station to all access users in the target base station within a certain period of time.

The division of a part from the fixedly allocated random access resources is performed periodically.

The threshold value of access times is set in advance, and before the mobile terminal accesses the target base station using the random access resources available to the handover user, the method further includes:

Judging whether the number of self-accesses is greater than the preset threshold value, if not greater, accessing the target base station using random access resources available to the handover user, otherwise, accessing fails and skipping this process;

The access times thresholds of all mobile terminals in the base station are different. In the present invention, a part of the fixedly allocated random access resources is specially provided for switching users, thereby fully ensuring the performance of switching users, simultaneously greatly improving switching speed and success rate, and reducing packet loss rate.

Description of drawings

FIG. 1 is a schematic flow diagram of a handover user accessing a target base station in the prior art;

Fig. 2 is the schematic flow chart realizing the method of the present invention;

FIG. 3 is a schematic diagram of an embodiment of the present invention to specifically divide resources;

Fig. 4 is a schematic flow chart of a specific embodiment for realizing the method of the present invention.

Detailed ways

In order to increase the access success rate of mobile terminals switching between base stations, the present invention divides a part of fixedly allocated random access resources exclusively for switching access resources available to users.

Referring to shown in Figure 2, realizing the method of the present invention comprises the following steps:

Step 201, allocate a part of the fixedly allocated random access resources as random access resources available to handover users.

Step 202, the mobile terminal in the source base station accesses the target base station by using the random access resources available to the handover user in the target base station.

The specific rules for dividing resources in step 201 above can be set according to spreading codewords, time, frequency, space or any combination thereof. Since random access methods include initial random access and random access of switching users, the fixedly allocated random access resources can be divided into two parts: one part is used for initial random access of users in the cell, and the other is used for initial random access of users in the cell. A part is used for random access of switching users.

Referring to FIG. 3 , the figure includes four parts 3a, 3b, 3c, and 3d, respectively representing four implementations of resource division in the present invention. Among them, Fig. 3a is a method of dividing resources according to time, Fig. 3b is a method of dividing resources according to frequency, Fig. 3c is a method of dividing resources according to codewords, and Fig. 3d is a method of dividing resources according to time domain and frequency domain. In addition, n represents the total number of random access resources that can be used in the cell; k is the dividing point between the initial random access and the access resource used to switch users among the n random access resources that can be used, and k <n. In the four ways shown in the figure, access resources 1~k are allotted to initial access users in the cell, and access resources (k+1)~n are allocated to users handed over to the cell.

The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

In this embodiment, firstly, according to the ratio of handover users and initial access users in each time period within a long period of time, the access resource division ratio of the cell is determined, and then the access resources are divided into two parts. Among them, a part is used for the initial random access of the user in the cell, and the other part is used for switching the available access of the user. Of course, the system can pre-set a period or time of a certain ratio to continuously perform self-adaptive adjustments. This time can be performed every few hours, days or even longer, and the specific time can be set by the operator.

Referring to Fig. 4, the method for realizing handover user access target base station in this embodiment includes the following steps:

Step 401, the source base station notifies the mobile terminal in the cell of its surrounding network topology, that is, the adjacent base stations of the cell;

Step 402, the mobile terminal in the cell negotiates with the base station, or independently decides the measurement cycle or time;

Step 403, the mobile terminal performs signal measurement on the surrounding cells according to the measurement period or time determined in step 402, and reports the measurement result to the RNC, and the RNC determines whether the mobile terminal should be handed over according to the signal strength of each base station, and thereafter will Notify the mobile terminal of the determination result; after receiving the notification, the mobile terminal judges whether it needs to switch, and if so, notifies the source base station that it will switch to the cell of the target base station, otherwise, jumps out of this process;

Step 404: After receiving the notification that the mobile terminal will be handed over to the target base station, the source base station notifies the target base station of necessary information related to the mobile terminal, specifically including user capability information and service information corresponding to the mobile terminal;

Step 405, the target base station judges whether it has access resources available to the handover user, and if so, randomly selects one from the access resources available to the handover user, and sends the access resource and its own timing and power information to the source base station, otherwise, the access fails;

Step 406: After receiving the access resource, timing and power information sent by the target base station, the source base station forwards the received information to the mobile terminal;

Step 407: After receiving the access resource information, timing and power information of the target base station, the mobile terminal performs timing adjustment according to the timing information, adjusts its own uplink transmission power according to the power information, and uses the access resource information specified by the target base station. Resources are accessed to the target base station.

In the above process, step 401 can be performed periodically, and its execution frequency is relatively low, usually only a few times a day at most, or only once in a few days, or for a longer period of time. In the specific switching process, it only needs to repeatedly execute steps 402 to 407. In step 405, if the target base station determines that it has no access resources available for handover users, two situations can be adopted at this time, one situation is to make the mobile terminal wait for a period of time, and then continue to judge whether there are handover users Available access resources, if there are, then allocate resources to the mobile terminal, if not, the access fails; another situation is that the target base station takes one of the initial random access resources allocated by the cell for handover The base station will not respond to the initial random access user who uses the resource in this cell. At this time, in order to ensure the performance available to the handover user, the random access performance of the user in the local cell may be reduced.

In addition, the base station may pre-set a threshold value of access times for the handover user, and if the user fails to access successfully within the threshold number of times, the handover of the user fails. Certainly, the threshold values corresponding to each user may be equal or unequal. Generally speaking, the higher the level of the user, the greater the corresponding threshold should be.

It should be noted that regardless of soft handover or hard handover, if the system requires synchronization, especially uplink synchronization, the user must perform an access process to adjust parameters such as timing and power when handing over to the target cell. Therefore, the method of the present invention can be applied to soft handover or hard handover.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (10)

1. A method for a mobile terminal switching between base stations to access a target base station, characterized in that the method comprises: The target base station divides a part of the fixedly allocated random access resources as random access resources available to handover users; A mobile terminal that performs handover between the source base station and the target base station accesses the target base station by using random access resources available to the handover user. 2. The method according to claim 1, wherein said accessing further comprises: B1. The mobile terminal sends a message to the source base station to switch to the target base station; after receiving the message, the source base station sends the mobile terminal capability information and service information to the target base station; B2. After receiving the capability information and service information of the mobile terminal, the target base station designates random access resources for the mobile terminal; B3. The target base station forwards the specified access resources and the power and timing information of the local terminal to the mobile terminal through the source base station; the mobile terminal adjusts the transmission power and timing according to the power and timing information sent by the target base station, and uses the specified access resources to access the target base station. 3. The method according to claim 1 or 2, characterized in that the method further comprises: from the fixedly allocated random access resources, the target base station uses the part except the random access resources allocated to handover users as the user Random access resource for initial random access. 4. method according to claim 2, is characterized in that, described step B2 further comprises: B21. The target base station judges whether it has random access resources available to the handover user, and if so, selects one of the random access resources available to the handover user as the access resource of the mobile terminal, and then performs step B3, Otherwise, execute step B22; B22. Determine whether you still have random access resources available to non-handover users in the random access resources that are fixedly allocated, and if so, select one of them as the access resource of the mobile terminal, and then perform step B3, otherwise , the access failed. 5. The method according to claim 1 or 4, wherein the random access resources available to the handover user are divided from fixedly allocated access resources according to certain rules. 6. method according to claim 5, is characterized in that, described certain rule is according to spreading code word, time, frequency, space, or any combination of four presets. 7. The method according to claim 1, wherein said dividing a part from the fixedly allocated random access resources is based on all access users in the target base station occupied by handover users in the target base station within a certain period of time The ratio is determined. 8. The method according to claim 1, wherein said dividing a part of the fixedly allocated random access resources is performed periodically. 9. method according to claim 1, is characterized in that, The threshold value of access times is set in advance, and before the mobile terminal accesses the target base station using the random access resources available to the handover user, the method further includes: Judging whether the number of self-accesses is greater than the preset threshold value, if not greater, accessing the target base station using random access resources available to the handover user, otherwise, accessing fails and skipping this process; 10. The method according to claim 9, wherein the access times thresholds of all mobile terminals in the base station are different.

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