CN1592165A - Frequency domain load equalizing controlling method for use while initial access in wide band CDMA system - Google Patents

Abstract

The invention relates to an inter-frequency load balance control method during initial access in a wideband code division multiple access system, which relates to load balance in WCDMA. Including: RNC acquires received wideband power RTWP and transmitted carrier power TCP value from Node B; when UE initially accesses, RNC decides whether it is necessary for UE to equalize to a different-frequency cell according to the situation; if it decides to balance the UE to a different-frequency cell , then the different-frequency cell is used as the target cell, and the information of the corresponding different-frequency cell is sent in the connection establishment message sent to the UE; if it is decided not to balance to the different-frequency cell, the current cell is used as the target cell, and the information of the current cell is sent; The UE returns an establishment complete message in the target cell. The method described in the present invention is simple, logical and efficient, can realize the maximization of the capacity of the whole system, and facilitate the smooth access of subsequent UEs.

Description

Inter-frequency load balancing control method during initial access in wideband code division multiple access system

technical field

The invention relates to a load balancing method in a Wideband Code Division Multiple Access (WCDMA) system (hereinafter referred to as WCDMA), especially according to the load measurement value of a cell and its co-located and co-covered sub-district, that is, using the received total broadband power (Received Total Wide Band Power) (hereinafter referred to as RTWP) and/or transmitted carrier power (Transmitted Carrier Power) (hereinafter referred to as TCP) to determine the frequency when there is user equipment (User Equipment, hereinafter referred to as UE) initial access The specific method of load balancing among users.

Background technique

With the wide application and rapid development of mobile communication systems, many key technologies in mobile systems are becoming more and more perfect. While realizing normal communication of users, it is also necessary to consider how to obtain the best performance, and obtain the best performance for both the system and user equipment. Better satisfactory results, from the perspective of the system, it is hoped to access as many users as possible.

In the WCDMA system, the wireless environment of the UE is changing all the time during the mobile process. When the UE is far away from the base station or the wireless environment deteriorates, if the original transmission rate is still maintained, in order to ensure its service quality QoS (Quality of Service), under the effect of closed-loop power control, the base station will inevitably send signals with greater power, and the capacity of the system will also change accordingly.

Compared with other systems (such as GSM system and CDMA system), WCDMA system has many special features. Soft capacity and support for variable rate services are its major features. If appropriate measures can be taken, UE can be used in a cell with a small load. Receive service, for the system, can better ensure the access of subsequent UEs in the cell with higher load; for the user, it can get relatively better service quality. For areas with different frequency cells with the same site coverage and the same coverage, the sum of the capacities of multiple cells with the same coverage and different carrier frequencies constitutes the total capacity that can be achieved in this area. How to maximize the capacity of multi-carrier frequency areas is worthwhile. A subject of research.

The patent application number is 00127302.7 "A method of load balancing preprocessing in a mobile communication system", which explains that in a mobile communication system, by measuring the load conditions of adjacent cells, modifying system information parameters, that is, controlling users to select cells parameters, so as to guide users to access in cells with relatively low load. The idea described in this patent can only be used for the processing of same-frequency cells, and it is aimed at potential users who have not yet accessed the system. However, the patent does not give an explanation on how to deal with the situation of inter-frequency cells. There is no corresponding processing method in the patent as to how to deal with users entering the system.

Contents of the invention

The purpose of the present invention is to solve the problem that there is no specific implementation method for load balancing in the WCDMA system in the existing technical specifications, especially for a cell with the same site, the same coverage, and different frequencies, and proposes a frequency based on load measurement during initial access. load balancing method.

Technical scheme of the present invention comprises the steps:

(1) The radio network controller RNC (Radio Network Controller) obtains the receiving broadband power RTWP and transmitting carrier power TCP values reflecting the load condition from the Node B;

(2) When the UE initially accesses, the RNC determines whether it is necessary for the UE to balance to a different-frequency cell according to the preset threshold parameters, the load of the cell currently accessed by the UE, and the load of the same-site and same-coverage different-frequency cell;

(3) If it is decided to balance the UE to a different-frequency cell, the different-frequency cell will be used as the target cell, and the information of the corresponding different-frequency cell will be sent in the connection establishment message sent to the UE; if it is decided not to balance to a different-frequency cell, Then the current cell is used as the target cell, and the information of this cell is sent;

(4) The UE returns an establishment complete message in the target cell (the target cell may be the own cell or the inter-frequency cell specified in the connection establishment message).

In step (1), the radio network controller (RNC) obtains the received broadband power RTWP and the transmitted carrier power TCP value of the load condition of the cell, including the following steps;

(1.1) The RNC sends a public measurement control command for the cell to the Node B, requiring the measurement of the received broadband power RTWP and/or the transmitted carrier power TCP value, and setting the reporting conditions. For the periodic reporting method, the reporting period needs to be set etc. For event reporting, it is necessary to set the reporting threshold, trigger time, etc.;

(1.2) The Node B reports to the RNC the uplink receiving broadband power RTWP and/or transmitting carrier power TCP value of the corresponding cell when the reporting condition in the measurement control command sent by the RNC is met;

(1.3) RNC stores the results reported by Node B for use when needed.

In the above-mentioned step (2), the radio network controller RNC inquires about the load status of the currently stored sub-district and the coverage sub-district with different frequencies and the same coverage of the sub-district when there is a user equipment UE access to initiate a connection request (RRCConnection Request). There are several ways to judge the load status as follows:

(2.1) In a system where the uplink direction is limited, only the received wideband power RTWP received in the uplink direction can be selected as a reference for load comparison between cells;

(2.2) In a system where the downlink direction is mainly limited, you can only choose to use the TCP value of the transmit carrier power in the downlink direction as a reference for load comparison between cells;

(2.3) In systems where the uplink and downlink directions need to be considered comprehensively, the received broadband power RTWP received in the uplink direction and the transmit carrier power TCP value in the downlink direction can be used simultaneously as a reference for load comparison between cells.

In the above step (3), according to the decision made in step (2), the RNC will bring the corresponding information to the UE in the corresponding RRC Connection Setup (RRC Connection Setup) message, which may include the following content: A. The cell Frequency information; B. Scrambling code information of the cell; C. Radio link resource information.

In the technical solution of the present invention, it can also be considered that when the load of the current cell is below a certain threshold, regardless of the load status of the different-frequency and same-coverage cell, the currently accessed UE will not be balanced to the different-frequency and same-coverage cell. When the UE initially accesses, it first judges whether the load of the current cell is lower than a preset threshold value, if yes, it does not need to make subsequent judgments, and directly uses the current cell as the target cell; if not, the RNC The threshold parameter of the UE and the load of the cell currently accessed by the UE and the load of the same-site and same-coverage different-frequency cell determine whether the UE needs to be balanced to a different-frequency cell.

The method described in the present invention is simple, logical and efficient, and can well ensure that when the UE initially accesses the WCDMA system, the UE can receive services in a cell with a lower load as soon as possible, so that multiple carriers with the same coverage and different carrier frequencies The load of the cell is better balanced, so as to maximize the capacity of the entire system and facilitate the smooth access of subsequent UEs. In addition, the method of the present invention can also avoid possible frequent equalization processing from two aspects. On the one hand, by setting a threshold, under this threshold, regardless of the load status of the different-frequency and same-coverage cells, there is no need to perform equalization processing. new users; on the other hand, when comparing the loads of the two cells, a hysteresis threshold can be set, and only when the loads of the two cells exceed the hysteresis threshold can the real load balancing process be performed, so as to maintain the current access to the maximum extent. UE's quality of service.

Description of drawings

Fig. 1 is a general flowchart of initial access time-frequency load balancing in an embodiment of the present invention;

Fig. 2 is a flow chart of messages between RNC and Node B during inter-frequency load balancing at the time of initial access.

Fig. 3 is a flow chart of messages between RNC and UE during inter-frequency load balancing during initial access.

Fig. 4 is a general flow chart of load balancing between frequency and frequency during initial access according to another embodiment of the present invention.

Detailed ways

In the 3GPPTS25.331 specification, it is stipulated that in the WCDMA system, the public measurement report of the Node B can be reported in two ways: periodic reporting and event-triggered reporting. This method is mainly described for the periodic reporting method, but it is also applicable in the event-triggered reporting method.

The present invention makes full use of the measurement results reported by the NodeB in the WCDMA system. In the RNC, according to the reported current cell load situation and the load of the different-frequency and same-coverage cells, it is comprehensively determined whether the currently accessed UE needs to be balanced to other different carrier frequencies. Same coverage area.

Below in conjunction with accompanying drawing, the implementation of technical scheme is described in further detail:

When the method of the present invention is applied in the WCDMA system, in the measurement control command, the periodic reporting scheme is adopted for public measurement, and it also has important reference significance for the event-triggered reporting method.

The flow process of method core idea of the present invention is as shown in Figure 1, as can be seen from Figure 1:

Step 101, the RNC sends a common measurement control command (Common Measurement InitiationRequest) to the NodeB, requiring the NodeB to periodically measure and report the measured value of the RTWP and/or TCP; in sending the measurement control command, the gap (Report Periodicity), Filter coefficient (Measurement Filter Coefficient), etc.;

Step 102, the NodeB receives the dedicated measurement control command sent by the RNC, and performs measurement according to the requirements, and reports the measurement result when the reporting condition is met;

Step 103, after the RNC receives the reported result, store the RTWP and/or TCP value related to each cell reported by the NodeB; RTWP is a quantity that directly reflects the uplink interference of the cell, and TCP directly reflects the downlink transmit power of the cell One quantity, under the conditions determined by the cell planning, the two measurement quantities can respectively represent the uplink and downlink load of a cell;

Step 104, when the UE initiates an RRC connection request, compare the load conditions of the current cell and the different frequency and same coverage cell (see step 105), select a cell with a lighter load as the target cell, and if the load of the current cell is low, select the current cell As the target cell (seeing step 106), otherwise select a lower inter-frequency cell as the target cell (seeing step 107);

Step 108, for the RRC connection is set up in the situation of the dedicated channel, after the Node B of the target cell establishes the corresponding wireless link, the information of the link can be sent in the RRC connection establishment message (RRC Connection Setup) together with the frequency information etc. to UE;

In step 109, the UE returns an RRC Connection Setup Complete message (RRC Connection Setup Complete), and the subsequent process is the same as the normal processing process, that is, initial direct transmission and other processes are performed.

Figure 2 is the message flow between RNC and NodeB during the processing. Corresponding to (101) and (102) in Figure 1:

RNC sends a common measurement order (Common Measurement Initiation Request) to each Node B (step 201), which contains some important information such as measurement amount, reporting method, filtering coefficient, etc.; , return public measurement initial response (Common Measurement InitiationResponse) (step 202) (step 202) to RNC, and start to measure, when measuring while Node B finds and reaches reporting condition, NodeB sends common measurement report (Common Measurement Report) to RNC when reaching reporting condition Measurement Report) (step 203), for periodic report mode, just report a measurement result (step 204) to RNC every once in a while.

Fig. 3 is a flow of dedicated messages related to UE during processing. Corresponding to steps (104), (108), (109) in Fig. 1:

The UE initiates an RRC connection request (RRC Connection Request) (step 301), and the RNC, after receiving the connection request, makes a judgment, then decides to establish the target cell of the radio link, and sends a radio link establishment request to the Node B of the target cell (Radio Link Setup Request) (step 302), after Node B returns correct radio link setup response (Radio Link Setup Response) (step 303), send RRC connection setup message (RRC ConnectionSetup) (step 304) to UE, Fill in some information related to the target cell and the established link in the message, and after completing the synchronization in the air, the UE returns the RRC connection to the RNC to establish a complete message (RRC Connection Setup Complete) (step 305), and then enters the normal direct transfer process.

In order to avoid too many frequent equalization actions, in another embodiment shown in Figure 4, a step (110) is added on the basis of the embodiment shown in Figure 1, that is, it is preferentially judged whether the load of the current cell is low If it is a preset threshold value, then the current cell can be directly used as the target cell without making subsequent judgments. At the same time, in step (105), a hysteresis decision condition can be added, that is, the load of the different-frequency cell is required to be lower than the current cell by a certain threshold, and the different-frequency cell is used as the target cell, which can more effectively reduce the frequency due to frequency occurrence. Changes may cause connection failures.

Claims (5)

1. Load balance control method between the frequency when 1, initially inserting in the broadband CDMA system comprises the steps:

   (1) radio network controller obtains the reception broadband power and the emission carrier power value of reflection load condition from Node B;

   (2) when subscriber equipment initially inserts, radio network controller is according to the cell load of predefined threshold parameter and the current access of subscriber equipment with the load of site with the covering alien-frequency district, and whether the decision subscriber equipment is necessary balanced to alien-frequency district;

   (3) if decision with this subscriber equipment equilibrium to alien-frequency district, then alien-frequency district is as Target cell, sets up in the message in the connection that sends to this subscriber equipment, sends the information of corresponding alien-frequency district; If determine unbalancedly to alien-frequency district, then current area sends the information of this sub-district as Target cell;

   (4) subscriber equipment returns to set up in Target cell and finishes message.
2. Load balance control method between the frequency when 2, initially inserting in the described broadband CDMA system of claim 1 is characterized in that described step (1) comprises the steps:

   (1.1) radio network controller sends at sub-district public-measurement control command to Node B, require to measure and receive broadband power and/or launch the carrier power value, and set the condition report, for the periodic report mode, the cycle that the needs setting reports etc., for reporting events, the thresholding that the needs setting reports, triggered time etc.;

   (1.2) Node B is to the up reception broadband power of respective cell and/or emission carrier power value, during report condition in reaching the measurement control order that radio network controller sends, reports to radio network controller;

   (1.3) radio network controller stores the result that Node B reports, and uses during for needs.
3. Load balance control method between the frequency when 3, initially inserting in the described broadband CDMA system of claim 1, it is characterized in that: in the described step (2), radio network controller is when having subscriber equipment to insert, inquire about current storage this sub-district load condition and with the alien frequencies of this sub-district load with coverage cell, for the judgement of load condition following several method can be arranged:

   (2.1) be limited as in the main system at up direction, can only select the reception broadband power that adopts up direction to receive, as duty ratio reference between each sub-district;

   (2.2) be limited as in the main system at down direction, can only select to adopt down direction emission carrier power value, as duty ratio reference between each sub-district;

   (2.3) in the system that the uplink and downlink direction need be taken all factors into consideration, the reception broadband power and the down direction emission carrier power value that can adopt up direction to receive simultaneously are as duty ratio reference between each sub-district.
4. Load balance control method between the frequency when 4, initially inserting in the described broadband CDMA system of claim 1 is characterized in that in described step (3), radio network controller comprises: this cell frequency information of A. to the information that Target cell sends; B. the scrambling code information of this sub-district; C. air-link resources information.
5. Load balance control method between the frequency when 5, initially inserting in the described broadband CDMA system of the arbitrary at the most claim of claim 1, it is characterized in that: when subscriber equipment initially inserts, earlier judge whether the load of current area is lower than a threshold value that sets in advance, if, then can not carry out follow-up judgement, directly with current area as Target cell; If not, radio network controller is according to the cell load of predefined threshold parameter and the current access of subscriber equipment with the load of site with the covering alien-frequency district, and whether the decision subscriber equipment is necessary balanced to alien-frequency district.

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