CN101854684B - Handover type based method for optimizing handover parameters in wireless celluar communication system - Google Patents

Abstract

The invention proposes a method for optimizing switching parameters based on switching type in a wireless cellular communication system. Firstly, the switching type is judged according to the switching priority information, and then the switching parameters are optimized according to the corresponding switching type. In the present invention, the serving base station determines that the user equipment UE belongs to one of the handover type H1 based on radio quality, the handover type H2 based on moving speed, or the handover type H3 based on load status according to a preset priority algorithm, and according to the handover The type optimizes the corresponding handover parameters HOM (Handover Margin, handover difference) and TTT (time-to-tiger, trigger time). The invention optimizes the switching parameters according to the switching type of the user equipment, avoids the ping-pong effect, and reduces the switching time delay and unnecessary switching times.

Description

Method for Optimizing Handover Parameters Based on Handover Type in Wireless Cellular Communication System

technical field

The invention relates to the technical field of wireless cellular communication, in particular to a method for optimizing handover parameters based on handover type in a wireless cellular communication system. the

Background technique

In recent years, with the rapid development of wireless communication, a large number of new standards and systems have emerged, and with the emergence of new standards and systems, a large number of new technologies, new theories and new methods of analyzing problems have been proposed. the

At present, 3GPP (3rd Generation Partnership Project, 3rd Generation Partnership Project) has proposed LTE (Long Term Evolution, long-term evolution) system. The advantages of this LTE system include: higher data rate, shorter delay, better optimized packet handling, improved system capacity, and better coverage. the

In a wireless cellular communication system, mobility management (Mobility Management) plays an important role, and handover (HO, Handover) management function is an important part of mobility management. In the handover process, functions such as realizing session continuity during mobility, supporting seamless service handover process, and providing smooth handover for users moving between different networks have become hot research technologies nowadays. the

Specifically, since the mobile communication system adopts a cellular structure mobile station, it is necessary to perform inter-cell handover when crossing cells divided on the basis of space, that is, to complete the transfer of the air interface from the mobile station to the base station, and from the base station to the core network. Transfer accordingly. the

In both the first and second generation mobile communication systems, handover is performed in a handover method that forces communication to be easily interrupted. However, in the 3G (3rd Generation, third-generation digital communication) system, soft handoff is realized between cells using the same carrier frequency, that is, when a mobile user crosses a cell, it can be connected to the base stations of two cells at the same time. Changing the corresponding spread spectrum code can realize the switching function of "connect first and then disconnect", thus greatly improving the call quality during switching. the

In the LTE OFDM (Orthogonal Frequency Division Multiplexing) system, in order to reduce the handover delay and signaling overhead, it is still necessary to use hard handover, that is, when the handover occurs, the UE (User Equipment, user equipment) total The channel of the original base station is released first, and then the channel allocated by the new base station can be obtained, which is a "release-establishment" process. Wherein, the handover process takes place between transitional areas or sectors of two base stations, and there is a competition relationship between the two base stations or sectors. the

In the process of realizing the present invention, the inventor finds that there are at least the following problems in the prior art:

If the signal strength of two base stations changes sharply in a certain area, the UE will switch back and forth between the two base stations, resulting in a "ping-pong effect", which increases the burden on the system and increases the possibility of call drop. the

Contents of the invention

The invention provides a method for optimizing switching parameters based on switching type in a wireless cellular communication system, so as to avoid ping-pong effect and reduce unnecessary switching times. the

In order to achieve the above object, the present invention provides a method for optimizing handover parameters based on handover type in a wireless cellular communication system, said method comprising the following steps:

The serving base station obtains the priority of the handover type of the user equipment UE;

The serving base station determines the handover type of the UE according to the priority of the handover type;

The serving base station optimizes handover parameters according to the handover type of the UE, and performs handover according to the optimized handover parameters;

Wherein, the switching parameters include switching difference HOM, trigger time TTT, load parameters;

The serving base station optimizes handover parameters according to the handover type of the UE, specifically including:

When the handover type of the UE is the handover type H1 based on radio quality, the serving base station counts the total number of handovers N _total , the throughput T _throughout of the UE, the number of redundant handovers N _un and the number of lost handovers N _ms ;

If N _un > N _ms , and the throughput T _throughout is greater than the preset throughput threshold T _threshold , the serving base station increases the value of the handover difference HOM and keeps the value of the trigger time TTT unchanged;

If N _un <N _ms , and the throughput T _throughout is less than the preset throughput threshold T _threshold , the serving base station reduces the value of the handover difference HOM, and keeps the value of the trigger time TTT unchanged;

When the handover type of the UE is high-speed mobility in the handover type H2 based on moving speed, the serving base station reduces the value of the handover difference HOM, and keeps the value of the trigger time TTT unchanged;

When the handover type of the UE is low-speed movement in the handover type H2 based on moving speed, the serving base station increases the value of the trigger time TTT, and keeps the value of the handover difference HOM unchanged;

When the handover type of the UE is load-based handover type H3, the serving base station counts the number of handovers of the cell where the UE is located, and sets an overload handover threshold N _thrd ;

If the number of handovers exceeds the overload handover threshold N _thrd , the serving base station records that the cell where the UE is located is an overloaded cell, and optimizes and adjusts the load parameters so that the UE is handed over to meet the load parameters and meet the handover conditions. .

Preferably, the handover type of the UE includes: handover type H1 based on wireless quality, handover type H2 based on moving speed, and handover type H3 based on load status; the handover type H2 based on moving speed includes handover based on moving speed High-speed movement in type H2 and low-speed movement in type H2 based on movement speed switching;

The serving base station obtains the priority of the handover type of the user equipment UE, specifically including:

The serving base station sets the wireless quality-based handover type H1 to have a first-level priority of the handover type;

The serving base station sets the priority of the second-level handover type for high-speed movement in the handover type H2 based on moving speed;

The serving base station sets the load-based handover type H3 to have a third-level priority of the handover type;

The serving base station sets the priority of the fourth-level handover type for low-speed movement in the handover type H2 based on moving speed. the

Preferably, the serving base station determines the handover type of the UE according to the priority of the handover type, specifically including:

The serving base station obtains the redundant switching number N _un and the missing switching number N _ms ; and judges whether the redundant switching number N _un and the missing switching number N _ms are within a preset value range (0, N _max );

If the number of redundant handovers N _un and/or the number of lost handovers N _ms is not within the preset value range (0, N _max ), the serving base station determines that the handover type of the UE is the radio quality-based handover type H1;

If the number of redundant handovers N _un and the number of lost handovers N _ms are both within the preset value range (0, N _max ), the serving base station determines whether the number of cell reselections within the preset time period T _CRmax exceeds a preset threshold N _{CR_H} ;

If the number of cell reselections exceeds the preset threshold N _{CR_H} within the preset time period T _CRmax , the serving base station determines that the handover type of the UE is high-speed mobility in the handover type H2 based on moving speed;

If the number of cell reselections within the preset time period T _CRmax does not exceed the preset threshold N _{CR_H} , the serving base station determines whether the number of overload handovers exceeds the preset number;

If the number of overload handovers exceeds the preset number of times, the UE needs to be handed over from the cell, and the serving base station determines that the handover type of the UE is the handover type H3 based on load conditions;

If the number of overload handovers does not exceed the preset number of times, the UE does not need to be handed over from the cell, and the serving base station determines that the handover type of the UE is low-speed movement in the handover type H2 based on moving speed. the

Preferably, when the handover type of the UE is the radio quality-based handover type H1, the serving base station increases the value of the handover difference HOM, or decreases the value of the handover difference HOM, specifically:

The serving base station according to the formula

HOM＝αHOM _un +βHOM _ms

HOM _un = HOM _ms + δ, δ > 0

Increase the value of the switching difference HOM, or reduce the value of the switching difference HOM; the α and the β are switching coefficients; wherein,

$\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; un</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}<span\; class="notranslate">\; ,</span>$ $\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}<span\; class="notranslate">\; ,</span>$

The handover difference HOM _un corresponding to the redundant handover number, the handover difference HOM _ms corresponding to the lost handover number, and the δ are preset empirical values.

Compared with the prior art, the present invention has the following advantages: the switching parameters are optimized according to the switching type of the user, the ping-pong effect is avoided, the switching delay and unnecessary switching times are reduced, and the smooth progress of the switching is ensured. the

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort. the

Figure 1 is a framework diagram of a flat structure introduced into the 3GPP LTE system. the

Fig. 2 is the method flow chart of the optimized handover parameter based on handover type in a kind of wireless cellular communication system proposed by the present invention;

Fig. 3 is a schematic diagram of the relationship between the handover parameter HOM and the handover parameter TTT in the 3GPP LTE system;

Figure 4 is a schematic diagram of signaling interaction during the handover process when the UE performs handover between cells;

Fig. 5 is a flow chart of a method for optimizing handover parameters based on a handover type in a wireless cellular communication system proposed under a specific application scenario of the present invention;

6 is a schematic flow diagram of the source base station determining the handover type of the UE according to the measurement report of the UE and the priority of the handover type preset by the network in the present invention. the

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention. the

As shown in Figure 1, a flat structure is introduced in the LTE system, so that the LTE network has only two layers of nodes, namely the core network (CN) and the radio access network (RAN), and the UE is handled by the eNode B (base station) in the RAN. Therefore, the UE handover between eNode Bs in the LTE network is much higher than that between RNCs (Radio Network Controllers, radio network controllers) in UMTS (Universal Mobile Telecommunications System, Universal Mobile Communications System) switch. the

In the present invention, the handover type priority set in advance by the network can be used to assist the serving base station (eNodeB) to make a handover decision, and the judgment standard of the serving base station is the setting of parameters, that is, the optimal setting of parameters is correct for the connection between the serving base station and the UE. Seamless switching plays a key role. In the present invention, by optimizing the switching parameters, the "ping-pong effect" is avoided, unnecessary switching is ensured in the process of fast and seamless switching, the number of switching is reduced, and signaling overhead is saved. the

The present invention proposes a method for optimizing handover parameters based on handover type in a wireless cellular communication system, as shown in Figure 2, the method includes the following steps:

In step 201, the serving base station obtains the priority of the handover type of the user equipment UE. the

Wherein, the handover type of the UE includes: handover type H1 based on wireless quality, handover type H2 based on moving speed, and handover type H3 based on load status;

The moving speed-based switching type H2 includes high-speed moving in the moving speed-based switching type H2 and low-speed moving in the moving speed-based switching type H2. the

The serving base station obtains the priority of the handover type of the user equipment UE, specifically including:

The serving base station sets the priority of the wireless quality-based handover type H1 with the first level (optimal level) handover type;

The serving base station sets the priority of the handover type with the second level (suboptimal level) for high-speed movement in the handover type H2 based on moving speed;

The serving base station sets the load-based handover type H3 to have a third-level priority of the handover type;

The serving base station sets the priority of the handover type with the fourth level (worst level) in the handover type H2 based on moving speed for low-speed movement. the

Step 202, the serving base station determines the handover type of the UE according to the priority of the handover type. the

The serving base station determines the handover type of the UE according to the priority of the handover type, specifically including:

The serving base station obtains the redundant switching number N _un and the missing switching number N _ms ; and judges whether the redundant switching number N _un and the missing switching number N _ms are within a preset value range (0, N _max ); if the The number of redundant handovers N _un and/or the number of lost handovers N _ms is not within the preset value range (0, N _max ), then the serving base station determines that the handover type of the UE is the handover type H1 based on radio quality; if the The number of redundant handovers N _un and the number of lost handovers N _ms are both within the preset value range (0, N _max ), and the serving base station judges whether the number of cell reselections within the preset time period T _CRmax exceeds the preset threshold N _{CR_H} ; If the number of cell reselections exceeds the preset threshold N _{CR_H} within the preset time period T _CRmax , the serving base station determines that the handover type of the UE is high-speed mobility in the handover type H2 based on moving speed; If the number of cell reselections within the segment T _CRmax does not exceed the preset threshold N _{CR_H} , the serving base station judges whether the number of overload handovers exceeds the preset number; if the number of overload handovers exceeds the preset number, the UE needs to be handed over from the local cell, the serving base station determines that the handover type of the UE is load-based handover type H3; if the number of overload handovers does not exceed the preset number, the UE does not need to be handed over from the cell, the serving base station It is determined that the handover type of the UE is low-speed movement in the handover type H2 based on moving speed.

In step 203, the serving base station optimizes handover parameters according to the handover type of the UE, and performs handover according to the optimized handover parameters. the

Wherein, the handover parameters include handover difference HOM, trigger time TTT, and load parameters. the

The serving base station optimizes handover parameters according to the handover type of the UE, specifically including: when the handover type of the UE is the radio quality-based handover type H1, the serving base station counts the total number of handovers N _total and the throughput of the UE T _throughout , the number of redundant handovers N _un and the number of lost handovers N _ms ; if N _un > N _ms , and the throughput T _throughout is greater than the preset throughput threshold T _threshold , the serving base station increases the value of the handover difference HOM , and keep the value of the trigger time TTT unchanged; if N _un <N _ms , and the throughput T _throughout is less than the preset throughput threshold T _threshold , the serving base station reduces the value of the handover difference HOM, and keeps The value of the trigger time TTT remains unchanged; when the handover type of the UE is high-speed movement in the handover type H2 based on the moving speed, the serving base station reduces the value of the handover difference HOM, and keeps the value of the trigger time TTT unchanged. change; when the handover type of the UE is low-speed movement in the handover type H2 based on moving speed, the serving base station increases the value of the trigger time TTT, and keeps the value of the handover difference HOM unchanged; when the UE's When the handover type is load-based handover type H3, the serving base station counts the number of handovers of the cell where the UE is located, and sets an overload handover threshold N _thrd ; if the number of handovers exceeds the overload handover threshold N _thrd , the The serving base station records that the cell where the UE is located is an overloaded cell, and by optimizing and adjusting the load parameters, the UE is handed over to a cell that satisfies the load parameters and meets the handover conditions.

Further, when the handover type of the UE is the radio quality-based handover type H1, the serving base station increases the value of the handover difference HOM, or decreases the value of the handover difference HOM, specifically: the serving base station according to formula

HOM＝αHOM _un +βHOM _ms

HOM _un = HOM _ms + δ, δ > 0

Increase the value of the switching difference HOM, or reduce the value of the switching difference HOM; the α and the β are switching coefficients; wherein,

$\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; un</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}<span\; class="notranslate">\; ,</span>$ $\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}<span\; class="notranslate">\; ,</span>$

The handover difference HOM _un corresponding to the redundant handover number, the handover difference HOM _ms corresponding to the lost handover number, and the δ are preset empirical values.

It can be seen that in the present invention, the handover parameters are optimized according to the user's handover type, which avoids the ping-pong effect, reduces handover delay and unnecessary handover times, and ensures smooth handover. the

In order to illustrate the technical solution provided by the present invention more clearly, the method for optimizing handover parameters based on the handover type in the wireless cellular communication system in the present invention will be described in detail below in combination with specific application scenarios. In this application scenario, Figure 3 shows the relationship between various handover parameters during the handover process of the LTE system. The handover parameters include HOM (Handover Margin, handover difference), TTT (time-to-tiger, trigger time) and load parameters, etc. ; Of course, in practical applications, the switching parameters are not limited to this, and can be arbitrarily selected according to actual needs. In this application scenario, the above parameters are taken as an example for illustration. the

In the relationship between the various handover parameters shown in Figure 3, during the UE moving from the serving cell to the target cell, the RSRP (Reference Signal Received Power) of the serving cell gradually decreases, and the RSRP of the target cell gradually increases. At a certain moment, when the RSRP of the target cell is greater than the RSRP of the serving cell, and the difference is HOM, the serving base station corresponding to the serving cell starts TTT timing. If within the TTT time, the RSRP of the target cell is always greater than the signal power of the serving cell, and the difference is always greater than the HOM, at this time, the serving base station makes a decision to perform handover. In FIG. 3 , P(ms) is the time for signaling interaction. After the interaction is completed, the serving base station sends a handover command to the UE, and the UE starts handover to the target base station. the

Specifically, in the LTE system, when the UE performs handover between cells, the entire handover process may include steps such as "measurement-report-judgment-execution", as shown in FIG. 4 . When the radio conditions change, the UE measures the adjacent cells and sends a measurement report containing the information of the adjacent cells to the serving base station to which the UE belongs. During handover, signaling interaction is performed according to the identity of the target cell to complete the resource preparation of the target cell. the

In the subsequent process, the serving base station to which the UE belongs sends a handover command to the UE. The UE disconnects from the source cell according to the handover command, starts to synchronize to the target cell, and starts sending and receiving user data on the target cell. The serving base station to which the UE belongs releases the source cell. The wireless resources of the cell are handed over. the

Taking the UE handover between cells controlled by the source base station (ie, the serving base station) and the target base station as an example, as shown in Figure 5, the method for optimizing the handover parameters based on the handover type in the wireless cellular communication system specifically includes the following steps:

Step 501, the source base station determines the handover type of the UE according to the measurement report of the UE and the priority of the handover type preset by the network. the

Specifically, after receiving the measurement report from the UE, the source base station needs to judge whether the UE needs to be handed over according to the measurement report of the UE. If the UE needs to be handed over, the source base station needs to pre-set The priority of the handover type determines the handover type of the UE. the

Wherein, the switching type includes but is not limited to: switching type H1 based on wireless quality, switching type H2 based on moving speed, switching type H3 based on load status, and the like. the

(1) Type H1: Handover based on radio quality. Usually, the reason for handover based on radio quality is that the measurement report of the UE shows that there is an adjacent cell with better channel quality than the current serving cell, which is generally based on the measurement and judgment of the downlink reference signal power (RSRP). the

(2) Type H2: Switching based on moving speed. According to the standard of moving states stipulated in the existing agreement, the moving speed in type H2 is divided into two states: high-speed moving and low-speed moving. Among them, high-speed mobility: when the number of cell reselections exceeds N _{CR_H} within the time period T _CRmaxx , it is determined to be high-speed mobility, and the handover interval is very small at this time. Low-speed mobility: When the number of cell reselections within the time period T _CRmax does not exceed N _{CR_L} , it is determined to be low-speed mobility, and the handover interval is very long at this time.

(3) Type H3: switching based on load conditions. The handover based on the load status is generated in order to balance the load status among different RATs (Radio Access Technology, radio access technologies) belonging to the same operator when a given cell is overloaded. For example, if an LTE cell has become congested, some users need to be transferred to an adjacent LTE cell or an adjacent UMTS cell. the

In this step, the source base station determines the handover type of the UE according to the measurement report of the UE and the priority of the handover type preset by the network, which specifically includes:

(1) The source base station to which the UE belongs sends a measurement control message to the UE. the

(2) The UE sends a measurement report to the source base station. Wherein, the process of sending the measurement control message and the measurement report will not be described in detail in the present invention. When it is determined according to the measurement report sent by the UE to the source base station that the UE needs to be handed over, subsequent steps are performed. the

(3) The source base station determines the handover type for the UE according to the preset priority. Among them, each base station can set the priority according to the actual situation. In the present invention, only a preferred priority setting method is given, and other priority setting methods will not be described in detail in the present invention. . the

In general, because whether the call can be carried out normally is the focus of the user's attention. In the present invention, considering the handover of the UE, the downlink reference signal RSRP measurement is mainly used, that is, the type H1 is the priority first, and the type H2 is the second priority. The priority is second best, and finally the type H3 is the lowest priority. Among them, since type H2 includes high-speed movement and low-speed movement, the priority of high-speed movement in type H2 is higher than that of type H3, and the priority of lower-speed movement in type H2 is lower than that of type H3. the

Based on the above situation, as shown in Figure 6, in this step, the source base station determines the handover type of the UE according to the measurement report of the UE and the priority of the handover type preset by the network, which specifically includes:

Step 601, the source base station obtains the number N _un of redundant handovers and the number N _ms of lost handovers.

Among them, redundant handover refers to handover occurs, but the throughput of UE in this cell is still higher than the minimum throughput requirement of UE (can be limited by setting a threshold); The throughput of the cell is lower than the UE's minimum throughput requirement (which can be limited by setting a threshold). the

Step 602, the source base station judges whether the number N _un of redundant handovers and the number N _ms of lost handovers are within a preset value range (0, N _max ). Wherein, the N _max can be arbitrarily selected according to actual needs. If the number of redundant switches N _un and/or the number of lost switches N _ms is not within the preset value range (0, N _max ), then go to step 603, if the number of redundant switches N _un and the number of lost switches N _ms are both within the preset value If it is within the range (0, N _max ), go to step 604.

Specifically, if the redundant switching number N _un and the missing switching number N _ms calculated in the type H1 are not all within the set value range (0, N _max ) (if it is less than N _max , the original switching parameter does not need to be changed, If it is greater than N _max , there is an exception), it is considered that the RSRP measurement process is abnormal (in addition, a flag can also be set to indicate, for example, flag=0 means that the measurement is abnormal), at this time, it needs to be optimized according to the parameter optimization method of type H1 The optimization of HOM and TTT parameters, the optimization process will be described in detail in the subsequent steps.

If the number of redundant handoffs _Nun and the number of lost handoffs _Nms calculated in type H1 are all within the set value range (0, _Nmax ), it is considered that the RSRP measurement process is normal and no special situation occurs (in addition, it can also be Set a flag to indicate, for example, flag=1 means that the measurement is normal), at this time, it is not necessary to optimize the HOM and TTT parameters based on the type H1, but it is possible to consider whether the optimization is required in the case of type H2 and type H3 Toggle parameters, in this case type H2 can be given the highest priority.

Step 603, the source base station determines that the handover type of the UE is the radio quality-based handover type H1. the

Step 604, the source base station judges whether the number of cell reselections within the preset time period T _CRmax exceeds a preset threshold N _{CR_H} . Wherein, both T _CRmax and N _{CR_H} can be selected arbitrarily according to actual needs. If the number of cell reselections exceeds the preset threshold N _{CR_H} within the preset time period T _CRmax , then go to step 605; if the number of cell reselections within the preset time period T _CRmax does not exceed the preset threshold N _{CR_H} , then go to Step 606.

If the number of redundant handoffs N _un and the number of lost handovers N _ms calculated in type H1 are both within the set value range (0, N _max ), it is considered that the RSRP measurement process is normal, and type H2 and type H3 need to be considered , where the priority of high-speed movement in type H2 is higher than that of type H3, and the priority of type H3 is higher than that of low-speed movement in type H2.

Step 605, the source base station determines that the handover type of the UE is high-speed movement in the handover type H2 based on moving speed. the

Step 606, the source base station judges whether the number of overload handovers exceeds a preset number. If the number of overloaded handovers exceeds the preset number of times, the UE needs to be handed over from the cell, then go to step 607; if the number of overloaded handovers does not exceed the preset number, then the UE does not need to be handed out of the cell, then go to step 608. Wherein, the number of overload handovers refers to the number of times that the UE is handed over from the cell due to overload. the

Step 607, the source base station determines that the handover type of the UE is the load-based handover type H3. the

Step 608, the source base station determines that the handover type of the UE is low-speed movement in the handover type H2 based on moving speed. the

In step 502, the source base station classifies and counts the handover types of each UE and the subtypes included in each type, and optimizes handover parameters according to the statistical results. Among them, the subtypes under each type can be defined and set by themselves. For example, type H1 is further divided into subtypes redundant switching and lost switching, and type H2 is further divided into subtypes high-speed movement and low-speed movement. the

Specifically, according to various types of statistical results, calculation and optimization can be performed according to preset calculation formulas. Wherein, the handover parameters include but are limited to: handover difference HOM, trigger time TTT and load parameters, etc. In practical applications, the handover parameters can also be other parameters, for example, the handover parameters shown in Table 1, for other parameters , which will not be described in the present invention. the

parameters explain RSRP Reference Signal Received Power HOM switch difference TTT trigger time T _throughout UE throughput T _throughout UE throughput threshold

[0110] N _un Extra switch times _Nms Lost switching times N _CR , T _RCmax Specify when to enter the low or high mobility state: If the number of cell reselections within the time T _RCmax is lower or higher than N _CR , the UE enters the low or high mobility state (graded according to the number of times).

In this step, the source base station classifies and counts the handover types of each UE and the subtypes contained in each type, and optimizes the handover parameters according to the statistical results. Specifically includes: 1) The source base station according to the measurement report from the UE and its own storage The type statistical information used for handover preparation, and the calculation and optimization of handover parameters. Wherein, the statistical information includes statistical values of various types, statistical values of different subtypes under various types, corresponding switching parameters, and the like. 2) The source base station performs analysis according to different statistical values, and correspondingly adopts different handover parameters to handover the UE. the

In the present invention, the process of optimizing the switching parameters is specifically:

(1) For handover based on radio quality (type H1), that is, when the handover type of UE is handover type H1 based on radio quality, the source base station needs to count the total number of handovers N _total , the throughput of UE T _throughout , and the number of redundant handovers N _un and the number of lost handoffs N _ms ;

If N _un > N _ms , and the UE's throughput T _throughout is greater than the throughput threshold T _threshold , the source base station needs to increase the HOM value and keep TTT unchanged; if N _un < N _ms , and the UE's throughput T _throughout When it is smaller than the throughput threshold T _threshold , the source base station needs to reduce the HOM value and keep the TTT unchanged.

It should be noted that the above principle for judging the relationship between the number of redundant handoffs N _un and the number of lost handovers N _ms is based on whether the condition RSRP _T > RSRP _S + HOM is satisfied within TTT, and at the same time The relationship between throughput and throughput threshold needs to be measured.

Specifically, in the process of increasing or decreasing the HOM value, the source base station is based on the formula

HOM＝αHOM _un +βHOM _ms

HOM _un = HOM _ms + δ, δ > 0

Increase the HOM value, or reduce the HOM value; the α and β are switching coefficients; where,

$\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; un</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}<span\; class="notranslate">\; ,</span>$ $\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}<span\; class="notranslate">\; ,</span>$

The handover difference HOM _un corresponding to the redundant handover number and the handover difference HOM _ms and δ corresponding to the lost handover number mentioned above are all preset empirical values, which can be selected according to actual needs.

In summary, it can be seen that if N _un > N _ms , redundant handovers are dominant, that is, handovers occur, but UE throughput T _throughout is greater than the threshold T _threshold . At this time, the HOM value needs to be increased to reduce redundant handovers. At the same time, the TTT is kept unchanged to prevent the occurrence of the ping-pong effect, thereby saving system resources and ensuring the correct judgment of the handover.

If N _un < N _ms , the lost handover is dominant, that is, there is no handover, but the UE throughput T _throughout is smaller than the threshold T _threshold . To prevent the ping-pong effect from occurring, thereby ensuring the service quality of the UE and avoiding resource waste.

(2) For the switching of UE moving speed (type H2), it can be divided into high-speed movement and low-speed movement according to the situation. At this time, the number of cell reselections in the time period is measured and counted. When the handover type of the UE is the high-speed mobile in the mobile speed-based handover type H2, since the high-speed mobile needs to be handed over as soon as possible, it is necessary to lower the HOM value within the scope of ensuring that the call is not dropped, while keeping the TTT unchanged to avoid Ping-pong effect. the

When it is determined according to the number of cell reselections that the handover type of the UE is low-speed mobility in the handover type H2 based on mobile speed, since low-speed mobility does not require frequent handovers, the TTT value can be increased at this time to further prevent the ping-pong effect. At the same time, keep the HOM value unchanged to avoid the possibility of dropped calls. the

(3) For load-based handover (type H3), that is, the UE's handover type is load-based handover type H3, the source base station needs to count the number of handovers and set the overload handover threshold N _thrd . If the number of handovers exceeds the overload handover threshold N _thrd (for example, the number of handovers exceeds the overload handover threshold N _thrd due to overload), the source base station needs to record that the cell where the UE is located is an overloaded cell, and optimize and adjust the load parameters so that the The UE is handed over to a cell that satisfies the load parameter and meets the handover condition.

For example, if a certain UE is always handed over due to cell overload, the base station will always first consider the UE as the first handover object. Therefore, the target base station needs to selectively reject the handover of the UE to its own cell according to the load of the cell; at the same time, the source base station can also find a cell with a less serious load to hand over the UE so that the UE can be handed over to meet the load parameters. and meet the handover conditions; in this case, the load parameter may be a load condition. the

For another example, if a UE is always handed over because the cell service cannot meet its own needs, it means that the bandwidth required by the UE to carry its own required services is very large, and the bandwidth of the source cell is insufficient to meet the needs of the UE. business bandwidth. Therefore, the target base station needs to selectively refuse the UE to switch to its own cell according to the bandwidth of the cell; at the same time, the source base station can also find a cell with sufficient bandwidth to switch the UE, so that the UE can be switched to meet the load parameters and A cell that meets the handover condition; in this case, the load parameter may be a bandwidth condition. the

Step 503, the source base station performs handover to the UE according to the optimized handover parameters, and saves the optimized handover parameters of the UE. the

Specifically, after obtaining the optimized handover parameters, the UE needs to perform handover according to the handover parameters, that is, perform the handover process according to the relationship of each handover parameter shown in FIG. 3 and the optimized handover parameters HOM and TTT. the

Step 504, the source base station sends the optimized handover parameters to the target base station through a handover request message. the

After deciding to execute the handover, the source base station can selectively send the optimized handover parameters to the target base station, and the target base station can select a suitable target cell for the UE according to the optimized handover parameters, as the source base station for handover decision reference. the

Specifically, the optimized handover parameters can be transmitted between the source base station and the target base station through the X2 interface, or can be transmitted between the source base station and the target base station through the S1 interface and through the core network (CN), so as to satisfy The need for the switching process. the

Step 505, the target base station prepares handover resources according to the optimized handover parameters, and returns an ACK to the source base station. the

Step 506, the source base station sends a handover command to the UE. Wherein, the handover command carries resource information corresponding to the target base station, and the UE is handed over to the target base station. However, in practical applications, the base station can also take corresponding measures according to the handover type to ensure correct handover of the UE; for example, adopt some antenna technologies to improve coverage. the

Wherein, the execution relationship among the various steps in the present invention can also be adjusted according to actual needs. the

To sum up, in the present invention, switching parameters are optimized according to switching types of users, avoiding the ping-pong effect, reducing switching delay and unnecessary switching times, and ensuring smooth switching. the

Through the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be realized by hardware, or by software plus a necessary general hardware platform. Based on this understanding, the technical solution of the present invention can be embodied in the form of software products, which can be stored in a non-volatile storage medium (which can be CD-ROM, U disk, mobile hard disk, etc.), including several The instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute the methods described in various embodiments of the present invention. the

Those skilled in the art can understand that the drawing is only a schematic diagram of a preferred embodiment, and the units or processes in the drawing are not necessarily necessary for implementing the present invention. the

The serial numbers of the above embodiments of the present invention are for description only, and do not represent the advantages and disadvantages of the embodiments. the

Claims (4)

1. A method for optimizing handover parameters based on handover type in a wireless cellular communication system, characterized in that the method comprises the following steps: The serving base station obtains the priority of the handover type of the user equipment UE; The serving base station determines the handover type of the UE according to the priority of the handover type; The serving base station optimizes handover parameters according to the handover type of the UE, and performs handover according to the optimized handover parameters; Wherein, the handover parameters include handover difference HOM, trigger time TTT, and load parameters; The serving base station optimizes handover parameters according to the handover type of the UE, specifically including: When the handover type of the UE is the radio quality-based handover type H1, the serving base station counts the total number of handovers N _total , the throughput T _throughout of the UE, the number of redundant handovers N _un and the number of lost handovers N _ms ; If N _un > N _ms , and the throughput T _throughout is greater than the preset throughput threshold T _threshold , the serving base station increases the value of the handover difference HOM and keeps the value of the trigger time TTT unchanged; If N _un <N _ms , and the throughput T _throughout is less than the preset throughput threshold T _threshold , the serving base station reduces the value of the handover difference HOM, and keeps the value of the trigger time TTT unchanged; When the handover type of the UE is high-speed mobility in the handover type H2 based on moving speed, the serving base station reduces the value of the handover difference HOM, and keeps the value of the trigger time TTT unchanged; When the handover type of the UE is low-speed movement in the handover type H2 based on moving speed, the serving base station increases the value of the trigger time TTT, and keeps the value of the handover difference HOM unchanged; When the handover type of the UE is load-based handover type H3, the serving base station counts the number of handovers of the cell where the UE is located, and sets an overload handover threshold N _thrd ; If the number of handovers exceeds the overload handover threshold N _thrd , the serving base station records that the cell where the UE is located is an overloaded cell, and optimizes and adjusts the load parameters so that the UE is handed over to meet the load parameters and meet the handover conditions. 2. The method according to claim 1, wherein the handover types of the UE include: handover type H1 based on radio quality, handover type H2 based on moving speed, and handover type H3 based on load status; The switching type H2 of moving speed includes high-speed moving in the switching type H2 based on moving speed and low-speed moving in the switching type H2 based on moving speed; The serving base station acquires the priority of the handover type of the user equipment UE, specifically including: The serving base station sets the radio quality-based handover type H1 to have a first-level priority of the handover type; The serving base station sets the priority of the second-level handover type for high-speed movement in the handover type H2 based on moving speed; The serving base station sets the load-based handover type H3 to have a third-level priority of the handover type; The serving base station sets the priority of the fourth-level handover type for low-speed movement in the handover type H2 based on moving speed. 3. The method according to claim 2, wherein the serving base station determines the handover type of the UE according to the priority of the handover type, specifically comprising: The serving base station obtains the redundant switching number N _un and the missing switching number N _ms ; and judges whether the redundant switching number N _un and the missing switching number N _ms are within a preset value range (0, N _max ); If the number of redundant handovers N _un and/or the number of lost handovers N _ms is not within the preset value range (0, N _max ), the serving base station determines that the handover type of the UE is the radio quality-based handover type H1; If the number of redundant handovers N _un and the number of lost handovers N _ms are both within the preset value range (0, N _max ), the serving base station determines whether the number of cell reselections within the preset time period T _CRmax exceeds a preset threshold N _{CR_H} ; If the number of cell reselections exceeds the preset threshold N _{CR_H} within the preset time period T _CRmax , the serving base station determines that the handover type of the UE is high-speed mobility in the handover type H2 based on moving speed; If the number of cell reselections within the preset time period T _CRmax does not exceed the preset threshold N _{CR_H} , the serving base station determines whether the number of overload handovers exceeds the preset number; If the number of overload handovers exceeds the preset number of times, the UE needs to be handed over from the cell, and the serving base station determines that the handover type of the UE is the handover type H3 based on load conditions; If the number of overload handovers does not exceed the preset number of times, the UE does not need to be handed over from the cell, and the serving base station determines that the handover type of the UE is low-speed movement in the handover type H2 based on moving speed. 4. The method according to claim 1, wherein when the handover type of the UE is the radio quality-based handover type H1, the serving base station increases the value of the handover difference HOM, or decreases the handover difference The value of HOM, specifically: The serving base station according to the formula HOM＝αHOM _un +βHOM _ms HOM _un = HOM _ms + δ, δ > 0 Increase the value of the switching difference HOM, or reduce the value of the switching difference HOM; the α and the β are switching coefficients; wherein, $\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; un</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}<span\; class="notranslate">\; ,</span>$ $\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}}<span\; class="notranslate">\; ,</span>$ The handover difference HOM _un corresponding to the redundant handover number, the handover difference HOM _ms corresponding to the lost handover number, and the δ are preset empirical values.

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