WO2003065627A1

WO2003065627A1 - A method of managing and optimizing radio resources in a cdma system

Info

Publication number: WO2003065627A1
Application number: PCT/CN2003/000094
Authority: WO
Inventors: Yu Zhang; Yu Liu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2002-01-30
Filing date: 2003-01-28
Publication date: 2003-08-07
Also published as: CN1182672C; CN1435963A

Abstract

The present invention provides a method of managing and optimizing radio resources in a CDMA system, dealing with managing and optimizing radio resources method among different nodes in the CDMA mobile communication system. The method transmits the cell attribute information of the drift base station controller with which the user terminal currently establishes the link to the serving base station controller with which the initial link was established through the interface between the base station controllers, and classifies the said cell attribute information, then optimizes the radio resources management according to the cell attribute information, thus the serving base station controller where the terminal initial link established can preserve an optimizing radio resources management strategy, and finally improves the use efficiency of the radio resources, as well as the optimum guaranty of user's traffic quality.

Description

Method for optimizing radio resource management in code division multiple access system

Technical field

The present invention relates to a communication system, and in particular, to a method for optimizing radio resource management between different nodes in a code division multiple access (CDMA) cellular mobile communication system. Background of the invention

CDMA is a spread spectrum communication technology. Spread spectrum communication technology was mainly used in military communications in the early days. Due to its excellent performance, it will also be widely used in the field of civil communications. There are already commercial CDMA cellular mobile communication systems operating in telecommunication networks.

In the existing cellular mobile communication system, when a mobile station leaves one cell and enters another cell, the signal of the original cell received by the mobile station must be weaker and weaker, and the signal of the cell that it is entering is coming. The stronger. In order to maintain the communication quality of the mobile station, it is necessary to switch the connection to the mobile station from the original base station to a newly entered cell with a strong signal. This is the concept of handover in a cellular mobile communication system. In the process of a user's mobile terminal, due to its mobility, the system needs to be able to perform handover in a timely manner to keep the user always communicating with the cell with the best current signal quality.

In a CDMA mobile communication system, because different channels are distinguished by code resources rather than by time slots or frequencies, this makes soft handover technology possible. Soft handover means that the user terminal (UE) communicates with multiple cell base stations at the same time by using different channel codes in the same frequency band and the same time. The application of soft handover is one of the distinguishing characteristics of CDMA system from other systems. The use of soft handover improves the handover performance.

Due to soft handover, signals received by different base stations need to be combined on the network side. If these base stations belong to the same base station controller, the signals of different base stations are transmitted to the corresponding base station controller through the interfaces between the respective base stations and the base station controller, and then the integration is completed. and. But in addition, there are cases where different base stations belong to different base station controllers. The combined signal at this time needs to be transmitted to the base station controller where the user is connected through the interface between the two base station controllers. When a user at the border between two base station controllers gradually moves away from the serving base station controller to which they are connected due to mobility, a very likely situation is that all base stations communicating with the user belong to another drifting base station controller, That is in a separate state. But at this time, the signal still needs to be transmitted to the serving base station controller through the interface between the serving base station controller and the drift base station controller, and then the latter is transmitted to the core network.

A technique called migration is applied to this case. Migration is a series of signaling processes that ultimately enables the drifting base station controller to perform the role of serving the base station controller at the same time, and communicates with the core network through the base station controller. The interface on the side maintains communication with the core network, and the interface transmission resources between the original serving base station controller and the drift base station controller are released, and the interface transmission resources between the original serving base station controller and the core network are also released.

The user communicates with multiple cells at the same time, regardless of whether these cells belong to the same base station controller. In the serving base station controller that first establishes a connection with the user terminal, in order to achieve the most economical and reasonable use of the wireless resources of the cell and the more convenient use by the user, All need to perform radio resource management according to a certain algorithm. This has two advantages: 1) radio resource management saves operators valuable radio frequency resources; 2) but more importantly, it indirectly brings economic benefits to end users: moving without using radio resources Compared with communication systems, users can pay less for their telephone bills and enjoy higher quality services.

The radio resource management itself needs to obtain relevant information before it can be successfully completed. This includes the status of the user terminal, the status of the user service, the status of the cell connected to the user, the wireless environment in which the user is located, and so on. Some of this information is obtained by storing the information in a database, or some is obtained by measurements from the cell and the user terminal.

If the cells communicating with the user terminal do not belong to the same base station controller, information about these cells needs to be transmitted to the serving base station controller through the interface between the base station controllers; or Or, if all the cells belong to the same base station controller, but do not belong to the serving base station controller, and the system is not migrated, the information of these cells also needs to be transmitted to the serving base station controller through the interface between the base station controllers.

In a wideband code division multiple access (WCDMA) system, the interface between the base station controllers is called a lur interface, and it is an open interface. In the current 3GPP series of protocols, only the most necessary information is transmitted to the serving base station controller, including the scrambling code of the cell where the current handover is successful. Only a small amount of necessary cell information is transmitted to the serving base station controller in the message via the lur interface. This information can only ensure that the most necessary handover actions can be performed, but cannot meet the needs of the serving base station controller to optimally perform radio resource management. Many useful information that can promote the use efficiency of the cell radio resources are not transmitted to the serving base station controller, so the serving base station controller cannot optimally complete the radio resource management of the cell. This is a more prominent defect in the prior art. Summary of the Invention

In view of this, the main object of the present invention is to provide a method for optimizing radio resource management in a CDMA system, adding a lur interface to upload cell attribute information to a serving base station controller, and transmitting more useful cell attribute information to the serving base station. The controller classifies part of them to better implement radio resource management of the cell.

The purpose of the present invention is achieved by the following technical solutions: When the serving base station controller where the user terminal is initially connected and the drifting base station controller where the current connection is located are in a separated state or across different base station controller states, the serving base station controller is used. The interface with the drifting base station controller includes the cell information of the cell covered by the base station under the control of the drifting base station controller, including the scrambling code of the cell to be switched to the cell and its neighbors, and other small guarantees that the handover action of the base station controller can be performed. The necessary cell information is transmitted to the serving base station controller where the user terminal is initially connected. The key lies in transmitting from the drift base station controller to the serving base station controller. There is also cell attribute information related to radio resource management optimization strategies, including: cell user density characteristics, cell mobility characteristics, cell shape, cell size, cell sector shape, and cell latitude and longitude; serving base station control The device classifies the user density characteristics, mobility characteristics, and shape attribute information of the cell transmitted from the interface between the serving base station controller and the drifting base station controller, and performs radio resource management optimization based on all cell attribute information. Including optimized handover, power control, positioning, and channel allocation.

The cell attribute information described above specifically includes: The user density characteristic information of the cell is classified into a commercial area, a residential area, a suburb, and a village. The mobility characteristic information of a residential area is classified into a vehicle environment, a walking environment, and an indoor environment. The shape information of a cell is classified into an omnidirectional cell, a directional cell, a hexagon, and a circle. The cell size information includes the radius of the cell. The sector shape information of a cell is the angle of the sector. The longitude and latitude information of the cell is the coordinate information of the cell. The cell attribute information may also include all other information related to radio resource management policies.

The radio resource management performed by using the foregoing information includes the following methods and strategies: The user density characteristics of the cell and the service distribution characteristics of the users in the cell are used to determine the capacity of the public channel in the cell, and based on this, for each For a user with a specific service attribute and service rate, during channel allocation, it is determined that the user is established under a common channel or a dedicated channel, and these characteristics of the residential community further determine its channel parameters.

Utilize the mobility characteristics of the cell for optimal handover policy control, that is, for different types of cells, different handover algorithms are used. For communities in the vehicle environment, the focus is on preventing dropped calls, while in pedestrian and indoor environments, the focus is on preventing ping-pong switching.

Use the shape of the cell, the sector shape of the directional cell, and the size of the cell to locate the terminal.

Use the user density and mobility characteristics of the cell to perform different power control. For example, for users in the vehicle environment, the power control algorithm considers how to provide tracking speed; for indoor environments, it focuses on how to improve the accuracy of power control and reduce the remaining error in power control. That is, the power control algorithm is determined by the characteristics of the cell itself.

The method of the present invention transmits more cell attribute information to the serving base station controller through the Iur interface, thereby facilitating the serving base station controller to use these cell attribute information to better implement the cell attribute information classification and wireless of the serving base station controller. Optimization of resource management, so that the base station server where the user initially connects can maintain an optimized wireless resource management strategy, and ultimately bring about the optimized use efficiency of wireless resources and the best guarantee of user service quality. Brief description of the drawings

FIG. 1 is a schematic diagram of a user terminal connected only to a serving base station controller;

FIG. 2 is a schematic diagram of a user terminal connection in a state of a cross base station server;

Figure 3 is a schematic diagram of the user terminal connection in a separated state. Mode of Carrying Out the Invention

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

Schematic diagrams of node connections in the three states of CDMA system without base station controller migration, cross-base station controller, and separation are shown in Figure 1, Figure 2, and Figure 3, and Figures 1 to 3 are composed of the following parts: Core Network 1, serving base station controller 2, drifting base station controller 3, base station one 4, base station two 5, base station three 6, and user terminal 7, the interface between core network 1 and serving base station controller 2 is represented as an Iu interface, The interface between the serving base station controller 2 and the drifting base station controller 3 is represented as an Iur interface, the interface between the serving base station controller 2 or the drifting base station controller 3 and each base station is represented as an Iub interface, and the base station and the user terminal 7 The interface between them is represented as a Uu interface.

As shown in FIG. 1, the user terminal 7 initially establishes a connection with the serving base station controller 2 and starts communication, and the base station that has a wireless connection with the user terminal 7 is base station 4. Since the attributes of the base station-1 and the cell controlled by it are all stored at the serving base station controller 2, Online resource management strategies can be optimal.

The user terminal 7 will continuously report the signal quality of the surrounding cells it measures during the movement process. If the quality of these cells is good, the serving base station controller 2 may make a handover decision and perform a handover procedure. If these cells belong to the serving base station controller 2, the serving base station controller 2 can still perform optimal radio resource management.

The movement of the user terminal may also appear that the neighboring cell with a better signal measured by it is under the control of another base station controller, that is, the drift base station controller 3. If the serving base station controller 2 switches the decision to add the cell to the active set, it sends a radio link setup message Radio Link Setup to the drift base station controller 3 through the Iur interface.

According to the method of the present invention, in the radio link setup response message Radio Link Setup Response returned by the drifting base station controller 3 to the serving base station controller 2, the attribute information of the cell is brought back. The attribute information may include:

1) user density characteristics of the community, that is, the community belongs to a central business district, a residential area, a suburb, and / or a village;

2) mobility characteristics of the community, that is, the community belongs to a vehicle environment, a pedestrian environment, and / or an indoor environment;

3) the shape of the cell, that is, the cell belongs to an omnidirectional cell, a directional cell, a hexagon, and / or a circle;

4) the size of the cell, that is, the radius of the cell, etc .;

5) The longitude and latitude of the cell, that is, the coordinate information of the cell and so on.

6) Fan shape, angle, etc. of the directional cell.

If the target cell for the user handover is not under the control of the current serving base station controller, for each base station controller, storing the cell information controlled by each base station controller around it is too complicated and uneconomical. Generally, this method is used. The serving base station controller is configured with the information of the few neighboring cells in its immediate vicinity, while other cell information is transmitted to the Iur interface. Serving base station controller.

After the handover of the cross-base station server is successful, the CDMA system node connection state diagram is shown in Figure 2. The user terminal maintains connection with base station 1 and base station 2 at the same time, while base station 1 is under the control of the serving base station controller 2, and base station 2 5 is under the control of the drift base station controller 3.

The serving base station controller 2 classifies the user density characteristics, mobility characteristics, and shape attribute information of the cells according to the cell attribute information obtained from the Radio Link Setup Response message of the Iur interface, and optimizes all the cell attribute information according to the cell attribute information. The algorithm performs radio resource management to obtain optimized performance and quality of service. Radio resource management according to an optimized algorithm refers to optimized handover, power control, positioning, and channel allocation. The attribute information of the cell may also include all other information related to the radio resource management strategy.

Radio resource management using cell attribute information includes the following methods and strategies: Utilizing the user density characteristics of the cell and the service distribution characteristics of users in the cell to determine the capacity of the public channel in the cell, and based on this, for each A user with a specific service attribute and service rate decides to establish the user under a common channel or a dedicated channel during channel allocation, and further determines its channel parameters according to these characteristics of the cell. If the capacity of the common channel in the small area is large, the serving base station controller 2 allocates low-rate users to the common channel during channel allocation, thereby saving dedicated channel resources. Conversely, more user services need to be allocated to dedicated channels to ensure the quality of user services.

The user terminal 4 is located by using the shape of the cell, the sector shape of the directional cell, the size of the cell, and the like.

Use the user density characteristics and mobility characteristics of the cell for different power control. For example, for users in a vehicle environment, the power control algorithm considers how to provide tracking speed, For indoor environment, how to improve the accuracy of power control and reduce the remaining error of power control, that is, the power control algorithm is determined by the characteristics of the cell itself.

If the user terminal 7 continues to move within the range controlled by the drift base station controller 3 and a handover within the drift base station controller 3 occurs, since each handover brings the cell attribute back to the serving base station controller 2 through the Iur interface, the service The base station controller 2 can maintain optimal radio resource management for the user terminal 7.

If the current user terminal 7 only has a wireless connection with the base station two 5 and the base station three 6 and the cell to which the drift base station controller 3 belongs, as shown in FIG. 3, the method according to the present invention is still applicable.

The above description is only the preferred embodiments of the present invention, and is not intended to limit the protection scope of the present invention.

Claims

Claim

1. A method for radio resource management optimization in a code division multiple access (CDMA) system, when the serving base station controller where the user terminal is initially connected and the drifting base station controller where the current connection is located are in a separated state or across different base station controller states When transmitting, through the interface between the serving base station controller and the drifting base station controller, the cell information required by the base station controller under control of the drifting base station controller to ensure that the base station controller performs handover to the user terminal The serving base station controller where the initial connection is located, wherein the cell information mainly includes the scrambling code of the cell to be switched to and the neighboring cell, which is characterized in that:

Through the interface between the serving base station controller and the drifting base station controller, the drifting base station controller also transmits the cell attribute information related to the radio resource management optimization strategy of the cell covered by the base station under its control to The serving base station controller; the serving base station controller classifies the cell attribute information transmitted from the interface between the serving base station controller and the drift base station controller, and performs radio resource management optimization according to all the cell attribute information.

2. The method according to claim 1, wherein the cell attribute information transmitted from the drift base station controller to the serving base station controller at least comprises: user density characteristic information of the cell, mobility characteristic information of the cell, and cell Shape information, cell size information, sector shape information of the cell, and latitude and longitude information of the cell. .

3. The method according to claim 2, wherein the optimization of the radio resource management further comprises: determining a capacity of a common channel of the cell by using a user density characteristic of the cell; The user terminals in the cell are established under a common channel or a dedicated channel, and further determine their channel parameters.

4. The method according to claim 2, wherein the optimization of the radio resource management further comprises: using the mobility characteristics of the cell to perform optimal handover policy control. System, different handover algorithms are used for different types of cells.

5. The method according to claim 2, wherein the optimization of the radio resource management further comprises: using sector shape information of the cell, size information of the cell, and shape information of the cell to the user terminals in the cell. Position it.

6. The method according to claim 2, wherein the optimization of the radio resource management further comprises: performing different power control using user density characteristics and mobility characteristics of the cell.

7. The method according to claim 2, 3, or 6, characterized in that the user density characteristic information of the cell is performed according to whether the cell belongs to a commercial area, or a residential area, or a suburb, or a village, or any combination of the four. classification.

8. The method according to claim 2, 4, or 6, wherein the mobility characteristic information of the cell is classified according to whether the cell is in a vehicle environment, a walking environment, or an indoor environment.

9. The method according to claim 2 or 5, wherein the shape information of the cell is performed according to whether the cell belongs to an omnidirectional cell, or a directional cell, or a hexagon, or a circle, or any combination of the four. classification.

10. The method according to claim 2 or 5, wherein the size information of the cell is a radius of the cell.

11. The method according to claim 2 or 5, wherein the sector shape information of the cell is the angle of the sector.

12. The method according to claim 2, wherein the longitude and latitude information of the cell is coordinate information of the cell.