CN101626590B - Method for preventing conflict between moving load balance and moving robustness optimization function - Google Patents

Abstract

The invention provides a method for preventing a conflict between moving load balance and moving robustness optimization function, which adopts the main idea that when the moving load balance operation is carried out in an LTE-Advanced network, the adjustment of the moving load balance to a switching threshold needs to be limited in the tolerance range of the moving robustness optimization so as to prevent various switching problems caused by inaccurately adjusting the switching parameter by the moving load balance.

Description

A method to avoid conflicts between mobile load balancing and mobile robustness optimization

technical field

The present invention relates to the technical field of mobile communication, in particular to a solution for mobile robustness optimization (MRO, Mobility Robustness Optimization) and mobile load balancing (MLB, Mobility Load Balance) in LTE (Long-term Evolution, 3GPP long-term evolution) network ) The method for function conflict belongs to the field of mobile communication.

Background technique

In the 3GPP long-term evolution system, due to the large number and high complexity of network parameters, manual configuration and management overhead for parameter configuration are too large. In order to improve the operation and maintenance performance of the network and minimize the manual intervention in the configuration and management of the base station (enhanced Node B, eNB), 3GPP proposed the self-organizing network (Self-Organizing Networks, SON), which is considered to reduce cost and complexity effective means.

Self-organizing network is divided into self-configuration (Self-Configuration), self-optimization (Self-Optimization) and self-healing (Self-Healing) three parts. Self-configuration means that the newly deployed nodes learn the necessary basic system operation configuration independently through the "automatic installation process", so as to realize automatic configuration; The network is automatically adjusted; self-healing can automatically detect and locate most of the problematic places, and solve these problems through certain mechanisms.

Mobility Robustness Optimization (MRO) and Mobility Load Balancing (MLB) are two important use cases (Use Case) of the self-optimization process in the self-organizing network SON.

The setting of handover parameters between eNBs determines the position of the handover threshold. If the handover threshold is not set properly, it will lead to inappropriate handover of the UE and failure of the radio link. Such as ping-pong handover (Ping-Pong HO) and UE premature handover (Too EarlyHO), too late handover (Too Late HO) and radio link failure (Radio Link) caused by handover to the wrong cell (HO To A Wrong Cell) Failure, RLF). The MRO function refers to adjusting the corresponding handover parameters, such as Cell Individual Offset (CIO) and Time To Trigger (TTT), by counting UE handover problems, so as to avoid or reduce Improper handover and radio link failure.

Within the coverage area of the eNB, the load of the eNB will be too high due to reasons such as a large amount of traffic, thereby affecting the quality of service of the UE. The MLB function refers to changing the handover threshold by adjusting handover parameters, such as Cell Specific Offset, so that some UEs of high-load eNBs are handed over to low-load neighbor eNBs, thereby balancing the load among eNBs.

Currently, the MRO and MLB functions are independent of each other, and conflicts with each other are not considered. For example, the MRO function adjusts the handover threshold according to the detected ping-pong handover and wireless link failure, thereby reducing the occurrence of ping-pong handover and wireless link failure; at the same time, the MLB function is based on the consideration of balancing the load between eNBs , in order to make the UE of the high-load eNB handover to the low-load neighbor eNB, the handover threshold may be adjusted to the original position again, resulting in ping-pong handover and radio link failure reappearing. After that, the MRO function will adjust the switching threshold again according to the detected ping-pong switching and wireless link failure, but the MLB function may adjust the switching threshold to the original position again. In this way, the two functions will enter a cycle, during which problems such as ping-pong switching and radio link failure will occur in the UE.

Therefore, how to make the functions of MRO and MLB work together to avoid conflicts between the two when adjusting parameters has become a problem that needs to be solved urgently.

Contents of the invention

The technical problem to be solved by the present invention: overcome the deficiencies in the prior art, and propose a method for solving the conflict between mobile robustness optimization and mobile load balancing functions. The functional modules can all work normally, and the parameter adjustment between them will not lead to the invalidation of the optimization effect of another module.

MLB changes the handover threshold by adjusting handover parameters (Cell Specific Offset, etc.), so that some UEs of high-load eNBs are handed over to their neighbor eNBs, thereby balancing the load between eNBs; MRO adjusts handover related parameters (CellIndividualOffset, Timer to Trigger etc.), by changing the handover threshold and other parameters to optimize the handover, avoid or reduce inappropriate handover (Ping-Pong HO, Too Early HO, Too Late HO and HO to A Wrong Cell) and wireless link failure (Radio Link Failure , RLF) appears. Since both the MLB and the MRO operate by changing the switching threshold, conflicts may arise when both adjust switching-related parameters. For example, the MRO function adjusts the switching threshold according to the detected inappropriate switching, thereby reducing Ping-Pong switching and RLF; The inappropriate switching of the reappeared.

The invention proposes a method for solving the conflict between mobile robustness optimization and mobile load balancing functions. In this method, after an inappropriate handover occurs, the MRO learns about the handover problem through UE feedback, and through the interaction between eNBs, the MRO can learn the handover thresholds for various inappropriate handovers. The MRO notifies the MLB function module of these thresholds. When the MLB adjusts the switching threshold, as long as it does not adjust to the threshold where inappropriate switching occurs, conflicts with the MRO can be avoided.

Description of drawings

Figure 1 is a schematic diagram of Ping-Pong HO caused by handover threshold overlap;

Figure 2 is a schematic diagram of the MLB adjustment threshold for avoiding Ping-Pong HO;

Figure 3 is a schematic diagram of the MLB adjustment threshold to avoid Too Early HO;

Figure 4 is a schematic diagram of the MLB adjustment threshold for avoiding Too Late HO.

Detailed ways

The implementation method of the present invention will be illustrated below in conjunction with the accompanying drawings and three specific embodiments of the present invention.

Example 1

In the embodiment of the present invention, the Ping-Pong HO of the UE between adjacent eNBs is caused by inappropriate handover parameters. Figure 1 shows a schematic diagram of Ping-Pong HO caused by handover threshold overlap.

This embodiment provides a method for avoiding function conflicts between MLB and MRO after Ping-Pong HO robustness optimization is performed. The specific implementation steps are as follows:

1) After the MRO modules of eNB 1 and 2 that are neighbors detect that Ping-Pong HO occurs in the handover to the other eNB, they record the critical handover threshold interval when Ping-Pong HO occurs according to formula 1, which is denoted as T _{1, 2 , PingPong} . If the relevant parameters of eNB 1 or eNB 2 are updated, go to step 2, otherwise go to step 3;

T _1,2 = (H ₁ -CIO _1,2 )+(H ₂ -CIO _2,1 ) (1) In formula 1, H ₁ is the hysteresis value (Hysteresis) of eNB i, and CIO _i,j is eNB i is Offset maintained by eNB j (CellIndividual Offset)

2) The eNB notifies the neighbor eNB of its own updated H and CIO values through the X2 interface between the eNBs;

3) According to T _{1, 2, PingPong} calculates the threshold value for MLB adjustment, such as formula 2;

Threshold _{1, 2, PingPong} = T _{1, 2, PingPong} - H ₂ + CIO _2, 1 (2)

4) When eNB 1 is overloaded, use the MLB function for load balancing, and use formula 3 as a constraint condition to ensure that MLB adjusts the eNB handover parameters within the allowable range of MRO to avoid re-initiating Ping-Pong HO, as shown in Figure 2 Show.

H ₁ -CIO _{1, 2} >Threshold _{1, 2, PingPong} (3)

Example 2

In the embodiment of the present invention, Too Early HO is triggered because the eNB uses inappropriate handover parameters. This embodiment provides a method for avoiding the function conflict between MLB and MRO after the Too Early HO robustness optimization is performed. The specific implementation steps are as follows:

1) After the MRO module of eNB 1 detects that the handover to eNB 2 occurs Too Early HO, it records the hysteresis value H _{1, Early} and CIO _{1, 2, Early that cause the wrong handover.} . Among them, H _{1, Early} and CIO _{1, 2, Early} are respectively the hysteresis value (Hysteresis) used by eNB 1 and the cell offset (Cell Individual Offset) set by eNB 1 for eNB 2 when Too Early Ho occurs;

2) Calculate the handover threshold where Too Early HO occurs, such as formula 4;

Threshold _{1, 2, Early} = H _{1, Early} - CIO _{1, 2, Early} (4)

3) When eNB 1 is overloaded, use the MLB function for load balancing, and use formula 5 as a constraint condition to ensure that MLB adjusts the eNB handover parameters within the allowable range of MRO to avoid re-initiating Too Early HO, as shown in Figure 3 .

H ₁ -CIO _1,2 >Threshold _{1,2, Early} (5)

Example 3

In the embodiment of the present invention, Too Late HO is caused due to inappropriate handover parameters. This embodiment provides a method for avoiding the function conflict between MLB and MRO after the Too Late HO robustness optimization is performed. The specific implementation steps are as follows:

1) After the MRO module of eNB 2 detects that Too Late HO occurs in the handover to eNB 1, the MRO of eNB 2 records the hysteresis value H _{2, Late} and CIO _{2, 1, Late when Too Late HO occurs.} . Among them, H _{2, Late} and CIO _{2, 1, Late} are respectively the hysteresis value (Hysteresis) used by eNB 2 when Too LateHo occurs and the cell offset (CellIndividual Offset) set by eNB 2 for eNB 1;

2) The MRO modules of eNB 1 and eNB 2 transmit the H and CIO when Too Late HO occurs to each other through the X2 interface. The MLB module of the eNB combines T _{1, 2 and PingPong} related to the ping-pong handover to calculate an adjustable threshold range.

3) eNB 2 calculates the handover threshold where Too Late HO occurs, as shown in formula 6;

Threshold _2,1,Late ＝H _2,Late -CIO _2,1,Late (6)

4) When eNB 1 is overloaded, use the MLB function for load balancing, and use formula 7 as a constraint condition to ensure that MLB adjusts the eNB handover parameters within the allowable range of MRO, preventing the handover threshold from being adjusted to the extent that Too Late HO occurs ,As shown in Figure 4.

H ₁ -CIO _1,2 >T _1,2,PingPong -Threshold _2,1,Late (7)

Claims (4)

1.LTE-Advanced a kind of method of avoiding mobile robustness optimization to conflict with the moving load equalization function in the network is characterized in that:

Base station eNB carries out needing the relevant threshold parameter of record after the mobile robustness optimization parameter adjustment; When carrying out the moving load equalization operation; The adjustment of moving load equilibrium to handoff threshold is limited in the scope of mobile robustness optimization permission, causes switching problem to avoid the balanced wrong adjustment handoff parameter of moving load.

2.LTE-Advanced a kind of method of avoiding mobile robustness optimization to conflict with the moving load equalization function in the network is characterized in that:

Base station eNB is being carried out the threshold parameter that mobile robustness optimization parameter adjustment postscript picture recording closes: when robustness optimization is carried out in switching to Ping-Pong, write down critical handoff threshold interval T _PingPongAnd according to neighbours eNB handoff parameter calculating Ping-Pong handoff threshold; Base station eNB is carried out moving load when balanced, is the parameter adjustable extent that constraints limits the moving load equalization operation with self eNB handoff parameter and above-mentioned Ping-Pong handoff threshold.

3.LTE-Advanced a kind of method of avoiding mobile robustness optimization to conflict with the moving load equalization function in the network is characterized in that:

Base station eNB is being carried out the threshold parameter that mobile robustness optimization parameter adjustment postscript picture recording closes: when robustness optimization was carried out in switching to Too Early, record eNB handoff parameter setting was also calculated corresponding Too Early handoff threshold; Base station eNB is carried out moving load when balanced, is the parameter adjustable extent that constraints limits the moving load equalization operation with self eNB handoff parameter and above-mentioned Too Early handoff threshold.

4.LTE-Advanced a kind of method of avoiding mobile robustness optimization to conflict with the moving load equalization function in the network is characterized in that:

Base station eNB is being carried out the threshold parameter that mobile robustness optimization parameter adjustment postscript picture recording closes: when robustness optimization is carried out in switching to Too Late, according to neighbours eNB handoff parameter the corresponding Too Late handoff threshold of calculating is set; Base station eNB is carried out moving load when balanced, with self eNB handoff parameter critical handoff threshold interval T when PingPong taking place switch _PingPongAnd above-mentioned Too Late handoff threshold is the parameter adjustable extent that constraints limits the moving load equalization operation.

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