CN105376808A - Load-based switching method between LTE system and CDMA 2000 system - Google Patents

Abstract

The invention relates to a load-based switching method between different systems of LTE and CDMA2000, belonging to the technical field of mobile communication. This method aims at the handover problem of data services in the overlapping coverage scenario of the existing CDMA2000 network and LTE network, judges whether the load of the cell is overloaded according to the set standard, and automatically switches the heavy coverage of the cell or the edge user of the cell to the low-load one Adjacent cells, on the one hand, reduce the load of high-load cells, and on the other hand, coordinate the resources of adjacent cells. At the system level, the throughput of the entire network is improved, resource utilization is improved, and user services are guaranteed. The method well solves the inter-system handoff of data services with low real-time requirements between LTE and CDMA2000.

Description

A load-based handover method between different systems of LTE and CDMA2000

technical field

The invention belongs to the technical field of mobile communication, and relates to a load-based switching method between different systems of LTE and CDMA2000.

Background technique

At present, the network operated by China Telecom includes both LTE network and the existing 3G network CDMA20001X. In the early and middle stages of LTE network construction, multi-network coexistence and coordinated operation of multi-network cannot be avoided. In the 3G era, the CDMA2000 network of the telecommunication network has a wide coverage and high investment costs. How to seamlessly switch between LTE network and CDMA2000 network can directly affect user perception, so it has extremely important research value. The current method adopted by the industry is that the CDMA network is responsible for voice and data services, and the LTE network is mainly responsible for data services. For data services with low real-time requirements, seamless switching between LTE and CDMA networks will be an effective solution at present.

The handover between different systems is a vertical handover, and most of these handovers use the multi-attribute judgment theory. The vertical handover decision algorithm of different systems is based on various parameters, such as: available bandwidth, delay, jitter, access cost, bit error rate, transmission power, current power status of the mobile terminal and user preferences, etc. QoS (Quality of Service, Quality of Service) parameters and handover metrics need to be considered in the handover decision process. In the multi-attribute judging method, in the prior art, the analytic hierarchy process is mostly used for judging the vertical handover. When using Analytic Hierarchy Process (AHP, Analytic Hierarchy Process) for network selection, the network selection problem will be decomposed into several sub-problems, and a weight will be assigned to each sub-problem, and the relativity and consistency between the attributes of each layer need to be compared in pairs sex. The levels are roughly divided into three categories: 1) The highest level: there is only one element at the top level, which is generally the goal to be achieved to solve the problem, also known as the overall goal level; 2) The middle level: includes the intermediate links involved in achieving the overall goal, It can be composed of several sub-layers, including the constraints to be considered, multi-level sub-criteria, etc., also known as the criterion layer; 3) The bottom layer: represents various measures and alternatives that can be selected to realize the criterion, so it is called program layer.

However, the above method has the following disadvantages: 1) There are too many indicators and a large amount of data statistics, which increases the operation complexity of the equipment; 2) The precise calculation of eigenvalues and eigenvectors is more complicated; 3) It needs to be carried out in existing equipment. Software upgrades to collect and analyze various indicators are costly.

Contents of the invention

In view of this, the purpose of the present invention is to provide a load-based handover method between different systems of LTE and CDMA2000. The method is aimed at the handover problem of data services under the overlapping coverage scenario of the existing CDMA2000 network and the LTE network. According to the set standard Judging whether the load of the cell is overloaded, automatically switching the heavy coverage of the cell or the users at the edge of the cell to the adjacent cell with low load. At the layer level, the throughput of the entire network is improved, resource utilization is improved, and user services are guaranteed.

To achieve the above object, the present invention provides the following technical solutions:

A load-based switching method between different systems of LTE and CDMA2000, comprising the following steps:

Step 1: Cell detection: when CDMA and LTE overlap coverage, the load difference between the two systems is greater than the threshold Th1, and the load of the high-load system is greater than the threshold Th2, then start the load balancing between the systems;

Step 2: Select users: in a high-load system, randomly select user UEs with poor current signal quality;

Step 3: User detection: Start the measurement of the low-load system. If the location of the selected user UE meets the B2 event at this moment, select the user to perform inter-system handover; if the B2 event is not satisfied, return to step 2 and select Except Monitoring by other UEs;

Step 4: Re-monitoring: After switching over each UE, re-detect the cells of the two systems to check whether the two conditions of load balancing are still met, that is, the load difference between the two systems is greater than the threshold Th1, and the load of the high-load system greater than the threshold Th2;

Step 5: Whether to continue: If in step 4, the two threshold conditions of load balancing are still satisfied after re-monitoring, go back to step 2. If not, it means that the loads of the two systems have been balanced, and the algorithm ends.

The beneficial effect of the present invention is that: the method provided by the present invention can well solve the inter-system handover of data services with low real-time requirements between LTE and CDMA2000. This algorithm is simple and easy to implement, and can be directly deployed to the base station side. By switching users in a high-load cell, the load of the cell can be effectively reduced to avoid severe congestion. At the same time, the system coordinates the load of different standard networks, increases the average throughput of the network as much as possible, and improves the resource utilization efficiency of the community. Because the handover algorithm is simple and feasible, it avoids frequent handover of the UE, causing a ping-pong effect and increasing the link failure rate.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings for illustration:

Fig. 1 is a schematic flow sheet of the method of the present invention;

Figure 2 is a comparison diagram before and after load balancing;

Fig. 3 is a scene diagram of overlapping coverage of CDMA2000 and LTE.

detailed description

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

Aiming at the handover problem of data services in the overlapping coverage scenarios of the existing CDMA2000 network and LTE network, the present invention proposes a load-based handover algorithm between different systems, aiming to systematically improve the average throughput of the network and improve resource utilization efficiency.

Due to the different number of users, different cells have different degrees of busyness. Without load balancing, some cells will be overloaded, resources will be insufficient, severe congestion will reduce user experience; resources in adjacent cells will be idle, resulting in waste of resources. Load balancing can automatically detect the load of the network, judge whether the load of the cell is overloaded according to the set standard, and automatically switch the heavy coverage of the cell or the edge users of the cell to the adjacent cell with low load, on the one hand, reduce the load of the high load cell On the one hand, it coordinates the resources of adjacent cells, and on the system level, it improves the throughput of the entire network, improves resource utilization, and guarantees user services. The load-based handover is mainly performed according to the load condition of the cell, and its specific principle is shown in FIG. 2 .

Load balancing between different systems is a self-optimizing function, which minimizes manual intervention in network management and optimization tasks. Compared with ordinary mobility management without balancing, load balancing cannot reduce the user's QoS, the service capabilities of different access technologies must be considered, and the balancing solution should consider high-load and low-load network deployments, high-load cells will There is coverage of varying quality. Based on the above analysis, the load balancing under different systems needs to achieve: According to the handover mechanism, users at the edge of the cell are switched to the cell with low load; in the new situation, the load of the cell is balanced; increase the system capacity; minimize manual intervention Network management and optimization tasks.

In this embodiment, the scene where the CDMA2000 network overlaps with the LTE network is shown in FIG. 3 . In this scenario, the priority of the general LTE network will be higher than that of the CDMA network (eHRPD, EvolvedHighRatePackageData, evolved high-speed packet network, which is the evolution and enhancement of the original HRPD, that is, the CDMA2000EV-DO network), and users will preferentially camp on LTE under the network. This is likely to cause a high load on the LTE network and a low load on the CDMA2000 network. In order to perform load balancing, it is necessary to switch between different systems based on load.

Fig. 1 is the schematic flow chart of the method of the present invention, as shown in the figure, the load-based handover method between the different systems of LTE and CDMA2000 of the present invention, comprises the following steps:

Step 1: Cell detection: when CDMA and LTE overlap coverage, the load difference between the two systems is greater than the threshold Th1, and the load of the high-load system is greater than the threshold Th2, then start the load balancing between the systems;

Step 2: Select users: in a high-load system, randomly select user UEs with poor current signal quality;

Step 3: User detection: Start the measurement of the low-load system. If the location of the selected user UE meets the B2 event at this moment, select the user to perform inter-system handover; if the B2 event is not satisfied, return to step 2 and select Except Monitoring by other UEs;

Step 4: Re-monitoring: After switching over each UE, re-detect the cells of the two systems to check whether the two conditions of load balancing are still met, that is, the load difference between the two systems is greater than the threshold Th1, and the load of the high-load system greater than the threshold Th2;

Step 5: Whether to continue: If in step 4, the two threshold conditions of load balancing are still satisfied after re-monitoring, go back to step 2. If not, it means that the loads of the two systems have been balanced, and the algorithm ends.

In 3GPP TS36.331 (V12.6.0), there is a clear definition of handover triggering events, where A1-A6 events belong to handover triggering events under the same system, and B1-B2 events belong to handover triggering events under different systems. The optimization process of load balancing between LTE and CDMA2000 systems belongs to handover under different systems, so B1~B2 events should be considered. The entry condition of the B1 event only considers that the quality of the adjacent cell of the different system is higher than a certain threshold, and the trigger is started, which is easy to increase the number of handovers, and frequent handovers lead to a ping-pong effect. So consider the B2 event. In the 3GPP TS36.331 standard document, the B2 event is defined as follows: 1) The quality of the serving cell is lower than the threshold 1; 2) The quality of the neighboring cell is higher than the threshold 2. When two conditions are met at the same time, the source eNodeB initiates an inter-system handover request.

In the flow chart of the load balancing algorithm between different systems, it can be clearly seen that in the overlapping coverage cells of LTE and CDMA2000, the cell load is first judged. Only when the load difference of two adjacent cells of different systems exceeds a certain threshold, And the measurement of the B2 event will not be started until the high-load cell has exceeded a certain threshold. That is to say, the whole set of algorithms gives priority to the load difference of cells in different systems, and if the conditions are not met, the algorithm ends directly. Only after the load satisfies the handover condition, the signal quality of the cell will be further detected based on the B2 event, and only the user that meets the B2 event will be initiated by the source eNodeB for inter-system handover.

After the load threshold reaches the requirement, the reason for randomly selecting the UE (User Equipment, user equipment) of the high-load cell is that if the B2 event cannot be satisfied, the random selection of the UE under the high load will continue until the B2 event is satisfied. The advantage of selecting UE in this way is to simplify the operation. The device can also selectively select cell-edge UEs, but as long as the signal quality of different UEs needs to be evaluated, it increases the difficulty of device operation. Therefore, the cell UE is randomly selected here, and after several times of random selection, it is possible to select a UE that meets the handover requirement.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (1)

1. a load-based switching method between different systems of LTE and CDMA2000, is characterized in that: comprise the following steps: Step 1: Cell detection: when CDMA and LTE overlap coverage, the load difference between the two systems is greater than the threshold Th1, and the load of the high-load system is greater than the threshold Th2, then start the load balancing between the systems; Step 2: Select users: in a high-load system, randomly select user UEs with poor current signal quality; Step 3: User detection: Start the measurement of the low-load system. If the location of the selected user UE meets the B2 event at this moment, select the user to perform inter-system handover; if the B2 event is not satisfied, return to step 2 and select Except Monitoring by other UEs; Step 4: Re-monitoring: After switching over each UE, re-detect the cells of the two systems to check whether the two conditions of load balancing are still met, that is, the load difference between the two systems is greater than the threshold Th1, and the load of the high-load system greater than the threshold Th2; Step 5: Whether to continue: If in step 4, the two threshold conditions of load balancing are still satisfied after re-monitoring, go back to step 2. If not, it means that the loads of the two systems have been balanced, and the algorithm ends.