WO2006133630A1

WO2006133630A1 - A method for selecting a servicing node according to load status

Info

Publication number: WO2006133630A1
Application number: PCT/CN2006/001229
Authority: WO
Inventors: Sihong Zhou
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2005-06-15
Filing date: 2006-06-06
Publication date: 2006-12-21
Also published as: CN1882166A; CN100459795C

Abstract

A method for selecting a servicing node according to load status, dividing the load of each node in node resource pool equably into more than one load levels, the current load status for each node corresponds to one load level, LCDN obtains load level for each node in node resource pool, and determines the selecting probability corresponding to each node according to the load level for each node, then selects a servicing node for the user terminal according to the determined selecting probability. Thus LCDN determines higher selecting probability for the node that has lower load in node resource pool, which enables the load for each node in the node resource pool tends toward balanced. In addition, the present invention uses load levels as the criterion weighing the node’s load, which makes the weighing to node’s load more easily and more effectively. The present invention also describes in detail the process for transferring load information, which makes LCDN can obtain the current load status for each node in time, and makes the transferring for load information more reasonably and more effectively.

Description

Method for selecting service node according to load condition

The present invention relates to load balancing techniques, and more particularly to a method of selecting service nodes based on load conditions. Background of the invention

In the communication field, when there are multiple nodes of the same type that can provide services for the user terminal, one node needs to be selected as the service node of the user terminal, as shown in FIG. 1, the Node B node B ₂ node B _n is the same kind of node, that is, a node capable of achieving the same function, n nodes

B constitutes a node resource pool, and node B provides communication services for user terminals. The network side may further include the node A, so that the user terminal can establish a service connection with the node B through the node A to obtain the corresponding service. Any node B in the node resource pool can provide services for a certain user terminal, but the service performed by the user terminal can only be provided by one node B.

Generally, when the user terminal requests a service, the node A can select a node B as a service node of the user terminal for the user terminal in the node resource pool; if there is a signaling interface between each node B in the node resource pool, Node B selects a Node B as the service node of the user terminal for the user terminal in the node resource pool.

The methods for selecting the Node B for the user terminal in the node resource pool are as follows: 1. Random selection, that is, randomly selecting a Node B for the user terminal in the node resource pool; 2. Statically selecting, that is, configuring the user terminal and Corresponding relationship between each node B in the node resource pool, selecting the node B for the user terminal according to the configured correspondence relationship; 3. Round-robin selection, that is, sorting numbers for each node B in the node resource pool, each time selecting for the user terminal When serving a node, one node B is selected according to the sequence number; fourth, the user ID (User-ID) is used as the user. The terminal selects the service node, that is, sorts the number of each node B in the node resource pool, and selects the user-ID Mode n node B for the user terminal, where Mode is a modulo operation.

A typical application of the above-mentioned node resource pool is a core network (CN, Core Network) node pool in a Wideband Code Division Multiple Access (WCDMA) network, and the foregoing node A can be regarded as a radio access network (RAN, Radio Access). Network ) node, node B can be regarded as a CN node.

According to the 3rd Generation Partnership Project (3GPP) standard, the RAN node can be connected to multiple CN nodes to form a many-to-many correspondence. The RAN node can be a Radio Network Controller (RC) or a Base Station Controller (BSC). CN node CS domain for the mobile switching center (MSC, Mobile Switching Centre), CN packet switched domain for the node serving general packet radio service support node (SGSN, Serving GPRS Support Node) 0

The concept of the pool area is proposed in the 3GPP standard. The pool area refers to the area covered by multiple RAN nodes. When the user terminal roams in the pool area, the CN node serving the user terminal may not change, thus avoiding the change of the CN node. The resulting location update process is performed to reduce signaling interactions between CN nodes.

A pool area is usually served in parallel by multiple CN nodes, and of course can also be served by a CN node. When a pool area is served by multiple CN nodes in parallel, these CN nodes form a CN node pool, such as an MSC pool or an SGSN pool. A CN node pool can serve multiple pool areas at the same time, that is, one CN node pool can correspond to multiple pool areas.

Taking the Universal Mobile Telecommunications System (UMTS) as an example, in order to uniquely identify a CN node in a CN node pool, each CN node in the CN node pool is assigned one or more network resource identifiers (RI, Network Resource Identifier), and configure the assigned NRI in the CN node through operation and maintenance. Used to identify different CN nodes in a pool of CN nodes. When the CN node allocates a Temporary Mobile Subscriber Identity (TMSI) or a Packet Temporary Mobile Subscriber Identity (P-TMSI) to the user terminal, the CN node is inserted in the TMSI/P-TMSI. NRI. The NRI having a variable length of 0 to 10 bits is located from the 23rd bit to the 14th bit of the TMSI/P-TMSI. The TMSI is allocated by the CN node of the circuit domain, that is, the MSC, to the user terminal; the P-TMSI is allocated by the CN node of the packet domain, that is, the SGSN for the user terminal. The actual effective bit length of the NI in TMSI/P-TMSI depends on the network plan and can be configured through the Operation and Maintenance Center (OMC).

The correspondence between the NRI in the CN node pool and each CN node is configured in each RAN node of a pool area. In the CN node pool, each CN node is configured with a correspondence between the NRI and other CN nodes.

When the user terminal enters the pool area, the CN node that serves the user, that is, the service CN node carries the NRL of the service CN node in the TMSI/P-TMSI allocated to the user terminal in the pool area, and the user terminal establishes each time When the non-access stratum (NAS, Non-Access Stratum) of the CN node is connected, the RAN node routes the initial NAS message to the CN node corresponding to the NRI according to the NRI. In this way, the user terminal can use the same CN node in a pool area. It can be seen that the RAN node selects the CN node for the user terminal according to the user identifier, that is, the K I included in the TMSI/P-TMSI.

In the network construction, the network resource capacity can be greatly improved by adopting the node resource pool, which is embodied in: 1. If a node fails, other nodes in the node resource pool can be used to continue to provide services; Upcoming overload, some user terminals in the node can be transferred to other nodes in the node resource pool; 3. If the maintenance service (0&M) needs to stop the service provided by a node externally, other nodes in the node resource pool can be selected. Continue to provide external services; Fourth, if a new node is added to the node resource pool, Transfer some user terminals to the newly added node quickly enough.

As can be seen from the above description, the node resource pool has the advantage of load sharing, and the key to implementing load sharing is to be able to select a service node for the user terminal according to the load of each node in the node resource pool. As shown in FIG. 1, both node A and node B can select the service node B for the user terminal according to the load of each node B in the node resource pool. Therefore, these nodes performing the selection function can be referred to as load control decision nodes. (LCDN, Load Controlling and Deciding Node) ₀ If the selection of Node B is performed by Node A, the LCDN is located at Node A; If the selection of Node B is performed by Node B, the LCDN is located at the node of the node node resource pool. The load information is provided to the LCDN. When the LCDN selects a service node for the user terminal in the node resource pool, the node with the lowest current load is preferentially selected as the service node of the user terminal. In this way, when the LCDN selects a serving node for the user terminal in the node resource pool, it simply selects the node with the lowest current load. However, if a large number of user terminals access the network in a short time, only the node with the lowest current load is selected. As the service node of the user terminal, the load of the corresponding node is sharply increased, even overloaded; and simply selecting the node with the lowest load cannot make the load of each node in the node resource pool tend to be balanced. Summary of the invention

In view of this, an object of the present invention is to provide a method for selecting a service node according to a load condition, so that the load of each node in the node resource pool is more balanced.

In order to achieve the above object, the present invention provides a method for selecting a service node according to a load condition. Each node in a node resource pool divides a load level according to a load, and a load corresponds to a load level, and the current load of each node corresponds to a load. At the level, the method consists of the following steps:

A. The load control decision node LCDN obtains the load level of each node in the node resource pool; B. The LCDN determines a selection probability corresponding to each node according to a load level of each node;

C. The LCDN selects a service node for the user terminal according to the determined selection probability.

The step A further includes the step AO: the node in the node resource pool sends a load information message carrying the current load level of the current node to the LCDN.

The step AO further includes the step A01: the LCDN sends a load information request to the node in the node resource pool.

The LCDN performs the step A01, and further includes: the LCDN starts the load request timer, and waits to receive the load information message sent by the node in step AO. If the load request timer expires, the LCDN receives the step AO. The load information message sent by the node stops the load request timer; if the load request timer expires and the LCDN does not receive the load information message sent by the node in step AO, the LCDN sends the load information to the node in step AO again. request.

The load information request carries an LCDN identifier for identifying the LCDN.

The step AO further includes: the LCDN returning a load information response to the node in the step AO.

When the node performs the step AO, the method further includes: the node starts the load response timer, and waits to receive the load information response returned by the LCDN. If the node receives the load information response returned by the LCDN before the load response timer expires, the load is stopped. Response timer; if the load response timer expires and the node does not receive the load information response returned by the LCDN, the node again sends a load information message carrying the current load level of the node to the LCDN.

The load information message further carries: a node identifier, or a new node indication for identifying whether the node is a newly added node in the node resource pool, or an O-M indication for identifying whether the node needs to be operated and maintained, or any of the above The combination.

When the load information message carries the O&M indication, the load information message further carries: a time interval, which is used to indicate that the load information message is sent to perform a maintenance operation. The time interval between.

The step AO further includes the step A02: the node in the node resource pool detects that the load level of the node changes.

When the node performs the step A02, the method further includes: starting the load timer, after the load timer expires, the step AO further includes the step A021: the node determines whether the load information message needs to be sent to the LCDN, and if yes, performing the step AO; Otherwise, the load information message is not sent to the LCDN, and the flow of the present invention is ended.

The step A021 is: the node first determines whether the current load level is the same as the load level when the load timer is started. If the current load level is the same as the load level when the load timer is started, step AO is performed; if the current load level is started If the load level of the load timer is different, it is determined whether the current load level is the same as the load level before the load timer is started. If the same, the node does not send a load information message to the LCDN, and the process of the present invention ends; Then, the step AO is performed; or: the node determines whether the current load level is the same as the load level before starting the timer. If the same, the node does not send a load information message to the LCDN, and ends the process of the present invention; if not, executes Step A0.

The step B includes the following steps:

Bl and LCDN sort the nodes in the node resource pool according to the load level of the node, and accumulate the load levels of the nodes;

B2. The LCDN determines the selection probability corresponding to each node according to the accumulated result obtained in step B1 and the load level of each node, and the lower the selection probability according to the higher the load.

The node resource pool includes m nodes. The higher the load level of the node is, the larger the current load of the node is. The step B1 is: LCDN according to the load level corresponding to the node, the nodes in the node resource pool are The order in which the load level is increased or decreased is sorted and the sequence number is written, and the load levels of the nodes are accumulated; the step B2 is: LCDN Divide the load level of each node by the accumulated result obtained in step B1, and divide the result of the division as the intermediate probability of each node, and then exchange the intermediate probability of the two nodes whose sum of the node numbers is m+1, LCDN The intermediate probability after the interchange is taken as the final selection probability of each node.

The overload threshold is set in the LCDN, and the LCDN sets the selection probability of the node whose load level is greater than or equal to the overload threshold to 0. The m nodes do not include nodes whose load level is greater than or equal to the overload threshold.

If there are k load levels, then one load level represents the 1/k load of the node full load, and the increased load level of the node indicates that the load of the node increases.

The node resource pool includes m nodes. The higher the load level of the node is, the smaller the current load of the node is. The step B1 is: LCDN according to the load level corresponding to the node, the nodes in the node resource pool are The order in which the load level is increased or decreased is sorted and sequenced, and the load levels of the nodes are accumulated; the step B2 is: LCDN divides the load level of each node by the accumulated result obtained in step B1, and divides The result is the probability of selection for each node.

The overload threshold is set in the LCDN, and the LCDN sets the selection probability of the node whose load level is not greater than the overload threshold to 0, and the m nodes do not include the node _D whose load level is not greater than the overload threshold.

If there are k load levels, then 1 load level represents the 1/k load of the node full load, and the increased load level of the node indicates that the load of the node is reduced.

LCDN randomly orders nodes with the same load level, or sorts according to node processing power and capacity.

The LCDN directly sets the selection probability of the node that needs to be operated and maintained to 0. The m nodes do not include nodes in the node resource pool that need to be operated and maintained.

When a node is newly added in the resource node pool, the method further includes: the LCDN sets the selection probability of the newly added node to the maximum selection probability in the original node, or increases the node's maximum selection probability. The selection probability is set to a value greater than the maximum selection probability in the original node, and the remaining selection probability is assigned to each original node according to the steps B1 and B2, and the remaining selection probability is 1 and the selection probability of the newly added node difference.

The value of setting the selection probability of the newly added node to be greater than the maximum selection probability in the original node: LCDN sets a weighting coefficient, and if the weighting coefficient is a decimal, the selection probability of the newly added node is 1 and the sum of the decimals The product of the maximum selection probability in the original node. If the weighting coefficient is an integer, the sum of 1 and the integer is divided by the result of the integer, and the product of the largest selection probability in the original node; or a fixed probability is configured in the LCDN. The selection probability of the newly added node is the sum of the maximum selection probability and the fixed probability in the original node.

The node resource pool includes m nodes, and the step C further includes: the LCDN divides m intervals in a range of 0 to 1 according to the determined selection probability, and the interval corresponds to the node, and the length of each interval corresponds to the node. Selecting the probability; the step C is: the LCDN generates a random fraction, determines the interval to which the random fraction belongs, and selects a node corresponding to the interval as the serving node of the user terminal.

Setting a transition threshold in the LCDN, the method further includes: when the difference between the highest load level and the lowest load level is greater than or equal to the set transition threshold, the LCDN transfers some of the user terminals in the highest load node to the node with the lower load, Step C.

According to the method proposed by the present invention, the load of each node in the node resource pool is evenly divided into more than one load level, and the current load status of each node corresponds to a load level. The LCDN determines the selection probability of each node in the node resource pool according to the acquired load level of each node in the node resource pool, and selects the service node for the user terminal according to the selection probability. In this way, the LCDN determines a higher selection probability for nodes with lower load in the node resource pool, so that the load of each node in the node resource pool is more balanced.

In addition, the load level is used as an indicator for measuring the load of the node in the present invention, so that the measurement of the node load is simpler and more effective. The invention also provides a process for transmitting load information. The detailed description enables the LCD to timely acquire the current load status of each node in the node resource pool, and makes the transmission of load information more reasonable and effective. When the load level of the node changes, the corresponding node provides the current load level to the LCDN, so that the LCDN can dynamically determine the selection probability of each node according to the load level of each node in the node resource pool. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a schematic diagram of a node resource pool;

2 is a schematic diagram showing a load information transmission process in the present invention;

Figure 3 shows a flow chart for selecting a service node based on load conditions in the present invention. Mode for carrying out the invention

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings.

In the present invention, each node in the node resource pool divides the load level according to the load, and one load corresponds to one load level. For example, the load of each node in the node resource pool is evenly divided into more than one load level, and the current load of each node. The status corresponds to a load level. The LCDN determines the selection probability of each node in the node resource pool according to the load level of each node in the obtained node resource pool, and selects the service node for the user terminal according to the selection probability.

The factors determining the load in the prior art include one or more of the following: CPU (Central Processing Unit) occupancy rate, including the number of user terminals that activate user terminals and online user terminals, signaling and services The flow rate, the occupation of memory resources, and so on, the methods and indicators for evaluating the load of node devices produced by different manufacturers are very different. In the present invention, the load level is used as the only indicator of the load of the comprehensive evaluation node.

In the present invention, the load of the node is evenly divided into k load levels, and one load level represents 1/k of the full load of the node, and the current load status of the node is represented by the load level, each The current load status of a node corresponds to a load level. For example, the load of a node is evenly divided into 8 load levels, 1 load level represents 1/8 of the full load of the node, and when the node is half loaded, its load level is 4, and the load level when the node is unloaded can be set to 0. The load level increases as the load on the node increases. The load level at the full load of the node is set to 8. The load level at the node no load can also be set to 8. The load level increases with the load on the node. Instead, the load level at node full load is set to zero. The above-mentioned no-load does not mean that there is no user terminal in the node, but the load of the node is the lowest; full load does not mean that the load in the node has reached 100%, but the load of the node is the highest.

In the case where nodes produced by multiple manufacturers coexist, in order to enable the same load level to represent the same or similar load in different nodes, such as setting 8 load levels, the load level of node 1 and node 2 is 2, load level For the two nodes, the current load should be close to 1/4 of the full load. According to the actual experience of each node operation, the load level calculation method can be corrected by the maintenance operation. For example, the maintenance load is used to modify the load factor. Weighted value.

Each node in the node resource pool can report its own load information to the LCDN actively or passively. The specific implementation process is shown in Figure 2:

Step 201: The LCDN sends a load information request (Loading Information REQ) to the node in the node resource pool, and requests the corresponding node to provide current load information to the node. After the LCDN sends a load information request to the node, the load request timer may be started, and then wait for the current load information returned by the corresponding node; if the LCDN does not receive the current load information returned by the corresponding node until the load request timer expires, the LCDN may The load information request is sent to the corresponding node again. The specific structure of the load information request is described in Table 1.

Parameter Name Optional / Required Parameter Meaning

LCDN-ID M LCDN identification, if the RAN node is LCDN, the parameter is RAN-ID; if the CN node is LCDN, the parameter is CN-IDo Table 1 load information request structure

Where: M is a mandatory parameter carried in the load information request.

In the following cases, LCDN sends a load information request to the node in the node resource pool, which is described in detail below.

1. The load request period is set in the LCDN. When each load request period expires, the LCDN sends a load information request to the node in the node resource pool. The load request period can be for the entire node resource pool or for a single node in the node resource pool. If the load request period is for the entire node resource pool, when a load request period expires, the LCDN sends a load information request to each node in the node resource pool, and the LCDN can broadcast to each node in the node resource pool by broadcast. Load information request. If the load request period is for a single node in the node resource pool, when a load request period for a certain node expires, the LCDN sends a load information request to the corresponding node, and at this time, the LCD resource pool can be set for the node. The load request period of each node in the middle.

2. A node in the node resource pool does not provide its load information to the LCDN within the set time range. The set time range differs from the load request period in case one in that the time range can be relatively large. Value.

3. The LCDN has just been put into use, taking the CN node pool serving the pool area as an example. If the RAN node is used as the LCDN, after the new RAN node is added to the pool area, the load information request is sent to each CN node in the pool area; If the CN node is used as the LCDN, after the new CN node is added to the CN node pool, a load information request is sent to each CN node in the pool area.

Step 202: Each node in the node resource pool sends a load information message (Load Information) to the LCDN, where the load information message carries load information and status information, where the load information is the current load level of the node. After the node sends a load information message to the LCDN, the load response timer can be started, and then wait for the load information response returned by the LCDN; If the node does not receive the load information response returned by the LCDN until the load response timer expires, the node may again send a load information message to the LCDN. Load information message specific

Table 2 Load information message structure

Where: M is a mandatory parameter carried in the load information message.

0 indicates an optional parameter carried in the load information message.

In the following cases, the nodes in the node resource pool send load information messages to the LCDN, which are described in detail below.

After receiving the load information request sent by the LCDN, the node in the node resource pool sends a load information message to the LCDN in response to the load information request, where the load information message carries the current load level of the corresponding node.

2. A new node is added to the node resource pool. After the node is started, a load information message will be sent to the LCDN. Because it is a newly added node, the load information message carries the The current load level of the node is 0. If the load information message also carries a new node indication, the new node indicates that the corresponding node will be identified as a newly added node in the node resource pool. For example, when the new node indicates 1, the corresponding node indicates The node is a newly added node in the node resource pool, and the original node in the node resource pool can set the new node indication carried in the load information message sent to the LCDN to 0.

The node in the node resource pool periodically sends a load information message to the LCDN, where the load information message carries the current load level of the corresponding node.

4. When the load level of the node in the node resource pool changes, the corresponding node sends a load information message to the LCDN, where the load information message carries the current load level of the corresponding node.

5. If the node needs to stop the service provided by a certain node, the corresponding node sends a load information message to the LCDN. The load information message carries the O&M indication that the identity node will perform the maintenance operation. For example, when the 0 or M indicates 1, the corresponding information indicates The node performs maintenance operations, and the load information message also carries the current load level of the corresponding node.

The node is required to cancel the O&M operation on the node that performs operation and maintenance. The corresponding node sends a load information message to the LCDN. The load information message carries the O&M indication that the identity node will cancel the maintenance operation. For example, when the O&M indicates 0, the corresponding node will The maintenance operation is cancelled. The load information message also carries the current load level of the corresponding node.

Step 203: After receiving the load information message, the LCDN returns a load information response (Loading Information ACK) to the corresponding node, and notifies the corresponding node that the load information and status information sent by the corresponding node have been received. The specific structure of the load information response is described in Table 3.

Parameter Name Optional / Required Parameter Meaning

LCDN-ID M LCDN identification, if the RAN node is LCDN, the parameter is RAN-ID; if the CN node is LCDN, the parameter is CN-ID Table 3 load information response structure

Where: M represents the mandatory parameter carried in the response of the load information.

If the LCDN starts the load request timer after transmitting the load information request to the corresponding node, and the LCDN receives the load information message sent by the corresponding node before the load request timer expires, the LCDN stops the load request timer.

If the node initiates a load response timer after transmitting a load information message to the LCDN, and receives a load information response returned by the LCDN before the load response timer expires, the node stops the load response timer.

After receiving the load information message sent by the node in the node resource pool, the LCDN may obtain one or more of the following load information and status information by using the load information message: a unique identifier of the node; a current load level of the node; A new node indication indicating whether the corresponding node is a newly added node in the node resource pool; indicating that the node is to perform a maintenance operation with an O&M indication, for example, a node is identified by 1 to perform a maintenance operation, and a node identifying by 0 does not need to perform a maintenance operation or Cancel the maintenance operation, the LCDN can no longer select the node that needs to perform operation and maintenance as the service node of the user terminal, and can further transfer the user terminal in the node that needs to perform the maintenance operation to other nodes in the node resource pool; The interval between the load information message and the execution of the maintenance operation. When the O&M indicates 1, the parameter can be carried in the load information message.

In a complete load information transfer process, the steps 201, 202, and 203 shown in FIG. 2 are not necessarily all performed, but the various steps described above may be omitted, for example, only the execution may be omitted. Step 202 to step 203, or only steps 201 to 202 are performed.

In the present invention, the node in the node resource pool can send a load information message carrying the current load level to the LCDN when the current load level is changed, so as to avoid the node in the node resource pool frequently going to the LCDN due to load fluctuation. Send a load information message, The node can start the load timer when the load level change is detected. After the load timer expires, the node can first determine whether the current load level is the same as the load level when the load timer is started, if the current load level and the start load timing When the load level is the same, it is determined that the load level has changed, and the node sends a load information message to the LCDN. If the current load level is different from the load level when the load timer is started, it is determined whether the current load level is the same as the load level before the load level is changed before the load timer is started, and if they are the same, it is determined to be The load fluctuates, the node does not send a load information message to the LCDN; if not, it determines that the load level changes, and the node sends a load information message to the LCDN. In addition, after the load timer expires, the node can also directly determine whether the current load level is the same as the load level before starting the timer. If the same, it determines that the load is fluctuating, and the node does not send a load information message to the LCDN; if not, Then it is determined that the load level has changed, and the node sends a load information message to the LCDN.

For example, if the load level of a node in the node resource pool changes from 4 to 5, the node starts the load timer when it detects that the load level changes to 5. After the load timer expires, the current load level of the node is j. If j is still 4, it is determined that the load level when the load timer is started is changed to load fluctuation, and the node does not send a load information message to the LCDN; if j is not 4, it is determined that the load level does change, the node The LCDN transmits a load information message, and at this time, even if j is not 5, it indicates that the load level has changed.

The LCDN determines the selection probability of each node in the node resource pool according to the current load level of each node in the obtained node resource pool, and selects a service node for the user terminal according to the selection probability. The specific implementation process is as shown in FIG. 3:

Step 301: The LCDN acquires the load level of each node in the node resource pool. The specific process can be implemented by the load information transmission process described in FIG. 2, and each node in the node resource pool can actively provide the current load level to the LCDN, for example, a node. When the current load level changes, this can reduce the interaction between the LCDN and each node in the node resource pool; The LCDN is provided with its current load level ij according to the request of the LCDN.

Step 302 to step 303: The LCDN accumulates the load levels of the nodes in the node resource pool, and then determines the selection probability of each node according to the accumulated result and the load level of each node.

Step 304: The LCDN selects a service node for the user terminal according to the determined selection probability. In addition, if the O&M indication indicates that the node needs to perform operation and maintenance, the LCD and the LCDN no longer select the node as the serving node of the user terminal, that is, the selection probability of the node is determined to be 0, until the node sends the cancel operation. The new load information message indicated by the maintenance of O&M. If the new node indicates that the corresponding node is a newly added node in the node resource pool, the LCDN may select the corresponding node as the service node of all user terminals for a period of time, and re-determine the selection of each node in the node resource pool after a period of time. Probability; or LCDN sets the selection probability of the newly added node to be relatively high, and re-determines the selection probability of the original nodes in the node resource pool.

The process of selecting a service node for a user terminal according to the determined selection probability according to the determined selection probability is further described below by way of example.

One implementation manner of the present invention is: uniformly dividing the load of each node in the node resource pool into k load levels, k being an integer greater than 1, and one load level indicating a 1/k load of the node full load, the node's The current load status is represented by the load level, the current load status of each node corresponds to one load level, and the increase of the node load level indicates that the load of the corresponding node increases.

The node resource pool includes m nodes, and m is an integer greater than 1. The LCDN sorts the m nodes according to the current load level of each node acquired, and sorts the numbers according to the order of the nodes. The LCDN can sort the m nodes according to the increase of the load level, or sort according to the decrease of the load level. The following is an example of sorting according to the increase of the load level. The order of the load level is basically the same as the implementation of the load level. Narration.

The LCD can sort the m nodes in the node resource pool according to the increase of the load level. For example, the node with the lowest load level has a sequence number of 1, the node with the second lowest load level has a sequence number of 2, and so on, the load level. The highest node has the serial number m. If more than one node in the node resource pool has the same load level, the LCDN can arbitrarily or randomly order the nodes, that is, which node is in the front position, that is, where the serial number is smaller, and which node is in the rear, that is, the serial number is larger. The position of the LCDN can also be sorted according to the processing capacity and capacity of each node with the same load level, that is, the nodes with larger processing capacity and capacity are ranked first, that is, the serial number is smaller. Position, the smaller nodes such as processing capacity and capacity are placed in the back, that is, the position with larger serial number.

The load level of the i-th (i=l, 2,...,m) nodes among the m nodes sorted by LCDN is Loadj, so Loadi < Load ₂ <... < Load _(i .i) <Load;< Load(i ₊₁ )... < Load _m , the specific load L in each node is the same as the order of Load, also! ^ < ₂ <~ < L _{i . < L < L _mo LCDN accumulates the load levels of m nodes, ie Sum = Loadi + Load ₂ + · · · +Load; + · · . +Load _m .

The LCDN divides the load level of each node by Sum, and determines the intermediate probability of each node, that is, Pi=(Loadi I Sum). The intermediate probability corresponding to each node in the node resource pool can be seen in Table 4.

Intermediate probability of each node in the node resource pool

After determining the intermediate probability of the m nodes in the node resource pool, the LCDN exchanges the intermediate probability of the node with the sequence number 1 with the intermediate probability of the node with the sequence number m, and the intermediate probability of the node with the sequence number 2 and the sequence number is m- The intermediate probability of the node of 1 is interchanged, and so on, the intermediate probability of the node with the sequence number i is exchanged with the intermediate probability of the node with the sequence number m+1-i, and the intermediate probability of the LCDN is used as the corresponding node. The final selection probability, which shows that the load level is the most The selection probability of node 1 with low, that is, the lowest specific load is the largest, and the selection probability corresponding to each node in the node resource pool can be seen in Table 5.

Selection probability of each node in the node resource pool

If m is an even number, the LCDN exchanges the intermediate probability according to the principle that the sum of the two node numbers is m+1 according to the principle that the sum of the two node numbers is m+1, so that the two-two interchange of the intermediate probability can be completed; if m is an odd number, then Except for the node with the sequence number (m+l)/2, the LCDN can search for the node number with the sum of the serial numbers of the remaining nodes as _m + i, that is, the LCDN can all the remaining nodes according to the sum of the two node numbers. The principle of +1 interchanges the intermediate probability, but for the node number (m+l)/2, the node number with the sum of m+1 is still (m+l)/2, therefore, the interchange of intermediate probability is visible. Interchange for its own intermediate probability.

For a node newly put into use in the node resource pool, in order to select the node more as a service node of the user terminal, the selection probability of the newly put-on node may be set as the selection probability of the node with the node number 1 or set. What is the probability of selection for a node with a node number of 1? : „Larger, for example, if the weighting coefficient K is configured in the LCDN, for example, the weighting coefficient K is a decimal, then the LCDN is the selection probability determined by the newly used node? ^ is P _m X (1+K), and for example, the weighting coefficient K If it is an integer, the selection probability P determined by the LCDN for the newly used node is Pm ^x (l+K) / K; for example, the fixed probability P _flxed is configured in the _LCDN , and the LCDN is the selection probability P determined by the newly used node. With P _m +P _fixed . After determining the selection probability P _new of the newly used node, LCDN re-determines the selection probability of the original nodes in the node resource pool, that is, assigns the remaining selection probability 1-P _new to the node resource pool. If there are multiple nodes in the node resource pool at the same time, the selection probability can be determined for the newly used nodes according to the above principles, as long as the sum of the selection probabilities of the existing nodes in the node resource pool is 1 can be. Another implementation manner of the present invention is: uniformly dividing the load of each node in the node resource pool into k load levels, one load level indicating 1/k of the full load of the node, and the current load status of the node by the load level It is indicated that the current load status of each node corresponds to one load level, and the increase of the node load level indicates that the load of the corresponding node is reduced.

The node resource pool includes m nodes, and m is an integer greater than 1. The LCDN sorts the m nodes according to the current load level of each node obtained, and sorts the numbers according to the order of each node. The LCDN can sort the m nodes according to the increase of the load level, or sort according to the reduction of the load level. The following is an example of the order of the load level. The order of the load level is basically the same as that of the load level, and is not described here.

The LCDN can sort the m nodes in the node resource pool according to the increase of the load level. For example, the node with the lowest load level has the sequence number 1, the node with the lowest load level has the sequence number 2, and so on, the load level is the highest. The node number is m. If more than one node in the node resource pool has the same load level, the LCDN can arbitrarily or randomly order the nodes, that is, which node is in the front position, that is, where the serial number is smaller, and which node is in the rear, that is, the serial number is larger. The location can be; LCDN can also sort these nodes according to the overall capacity and capacity of each node with the same load level, that is, the smaller nodes with the overall capacity and capacity are ranked first, that is, the serial number is larger. Position, the smaller nodes such as the overall capacity and capacity are placed in the back, that is, the position with the larger serial number.

I m through the first node after LCDN Sequencing (i = l, 2, ... , m) other nodes load stage ¹ J is Loadj, so _{that, Load]> Load 2> ·} ·> Load (i .i) > Loadi > Load ₍ i ₊₁₎ ... > Load _m , the specific load L in each node is exactly the opposite of Load, which is < L ₂ <... L(w) < Li < L( _i+1 ) ~ < L _m . LCDN accumulates the load levels of m nodes, namely Sum=Loadi+Load ₂ + . . . +Load;+ ... +Load _m .

LCDN divides the load level of each node by Sum, and determines the selection probability Pi of each node. That is, Pi=(Loadi / Sum), it can be seen that the selection probability of the node 1 with the highest load level, that is, the lowest specific load is the largest, and the selection probability corresponding to each node in the node resource pool can be seen in Table 6.

Table 6 Selection Probability of Each Node in the Node Resource Pool For a node newly put into use in the node resource pool, in order to select the node more as the service node of the user terminal, the selection probability of the newly put-on node may be set as a node. The selection probability of the node with the sequence number m is set to be larger than the selection probability Pi of the node with the node number of 1, for example, the weighting coefficient K is configured in the LCDN, and if the weighting coefficient K is a decimal, the LCDN is the newly used node. The determined selection probability P _new is (1+K). If the weighting coefficient K is an integer, the selection probability P _new determined by the LCDN for the newly used node is ? (1+)/ 1^; For another example, the fixed probability P flxed is configured in the _LCDN , and the selection probability P _new determined by the LCDN for the newly used node is

After determining the selection probability P _new of the newly used node, the LCDN re-determines the selection probability of the original nodes in the node resource pool, and allocates the remaining selection probability 1-P _new to the original nodes in the node resource pool. If multiple nodes are newly used in the node resource pool at the same time, the selection probability may be determined for the newly used node according to the above principle, as long as the sum of the selection probabilities of the existing nodes in the node resource pool is one.

The above description has no obvious execution order between the steps of sorting the nodes in the node resource pool according to the load level and accumulating the load levels of the nodes, and can be performed simultaneously; or performing the sorting on the nodes first, and then executing The load level is accumulated; the load level can also be accumulated first, and then the nodes are sorted.

In addition, the overload threshold can be further set in the LCDN, and the LCDN directly sets the selection probability of the node whose load level is greater than or equal to the overload threshold to 0, that is, the corresponding node is no longer selected as the service node of the user terminal, thus, the above m nodes do not include node resources Nodes in the source pool whose load levels are greater than or equal to the overload threshold

If a node in the node resource pool needs to perform maintenance operations, the LCDN sets the selection probability of the node that needs to perform the maintenance operation to 0, and no longer selects the corresponding node for the user terminal. Thus, the m nodes described above do not include the node. The nodes in the resource pool that need to be operated and maintained.

If the node resource pool has both a node whose load level is greater than or equal to the overload threshold and a node that needs to perform maintenance operations, and the LCDN sets the selection probability of the nodes in both cases to 0, then the above m The node does not include nodes in the node resource pool whose load levels are greater than or equal to the overload threshold, and nodes that need to be operated and maintained.

After determining the selection probability for each node in the node resource pool, the LCDN selects the service node for the user terminal according to the selection probability. The specific implementation process may be: LCDN determines the selection probability for each node in the node resource pool, at 0 m intervals are divided into the range of 1, the i-th interval corresponds to the i-th node, and the length of each interval is the selection probability of the corresponding node, and each node in the node resource pool corresponds to one of the intervals, corresponding to In Table 5, m intervals can be divided into (0, P _m ], (P _m , P _m + P _m . (P _m + P _m-1 , P _m + P _m .i+P _m - ₂ ] ...... (P _m + P _m .i+~+ P ₂ , 1), and the node with the sequence number 1 corresponds to the interval (0, P _m ), and the node with the sequence number ^{2 is} the interval (P _m , P _m + P :^] Correspondingly, and so on, the node with the number m corresponds to the interval (P _m + Pm.i+~+ P ₂ , 1), corresponding to Table 6, which can divide m intervals into (Ο, Ρ !) [Pi, Pi+ P ₂ ), [Pi+ P ₂ , Pi+ P2+P3)...... [Pj+ Ps+ + Pm-h 1), and the node with the sequence number 1 corresponds to the interval (0, Pi), and the sequence number is The node of 2 corresponds to the interval [P^Pi+ P, depending on Analogy, m is the number of nodes section

1) Corresponding; When selecting a service node for the user terminal, the LCDN generates a random decimal number, determines the interval to which the random decimal belongs, and then selects the node corresponding to the interval as the service node of the user terminal. Each of the above intervals may be a closed interval. If the random number generated by the LCDN is the critical point of the two intervals, the LCDN may randomly select one of the nodes as the service node of the user terminal, The node with a relatively small load can be selected as the service node of the user terminal.

It can be seen from the above description that the LCDN determines a higher selection probability for the node with lower load in the node resource pool, and each node in the node resource pool is selected as the selection probability of the user terminal service node corresponding to the length of the corresponding interval, and the interval The longer the length, the greater the probability that the random number generated by the LCDN falls within the range, and the probability that the corresponding node is selected as the user terminal service node is greater; however, since the LCDN generates a random fraction, the random fraction falls. In which interval is possible, therefore, LCDN does not concentrate on selecting a node for a period of time, and thus avoids a sharp rise in the load of a node.

For example, there are 5 nodes in the node resource pool. The increase of the node load level indicates that the load of the corresponding node increases. The selection probability determined by the LCDN for the five nodes according to the foregoing process is shown in Table 7.

Table 7 Selection probability of 5 nodes in the node resource pool

LCDN divides 4 intervals in the range of 0 to 1 according to the determined selection probability, (0,0.4] (0.4,0.7], (0,7,0.9], (0.9,1), and node 1 corresponds to the interval (0, 0.4), node 2 corresponds to interval (0.4, 0.7), node 3 corresponds to interval (0.7, 0.9), and node 4 corresponds to interval (0.9, 1). LCDN generates random when user node selects service node Decimal V, if the random fraction V is 0.3, the LCDN determines that the random fraction 0.3 falls in the interval (0, 0.4), therefore, selects node 1 as the serving node of the user terminal. If the random fraction V generated by the LCDN is 0.7, the LCDN It is determined that the random fraction 0.7 falls within the interval (0.4, 0.7), therefore, node 2 is selected as the service node of the user terminal; if the above intervals are closed intervals, the LCDN may select node 2 as the service node of the user terminal, or may select The node 3 serves as a service node of the user terminal. Since the load of the node 2 is lower than the load of the node 3, the LCDN can select the node 2 with a lower load as the service node of the user terminal among the node 2 and the node 3. In addition, the division of each interval may not be 0 as the starting position, and the selection probability shown in Table 7 is taken as an example. LCDN may divide such four intervals in the range of 0 to 1 according to the determined selection probability, [0] , 0.1], [0.1, 0.5], [0.5, 0.7], [0.7, 1], and node 1 corresponds to interval [0.1, 0.5], node 2 corresponds to interval [0.7, 1], and node 3 corresponds to interval [0.5, 0.7], node 4 corresponds to the interval [0, 0.1).

The case where the LCDN selects a service node for the user terminal includes but is not limited to: the user terminal accesses the node resource pool; the user terminal requests the node resource pool to provide the service service; the LCDN according to the load status of each node in the node resource pool, some or some The user terminals in the node are transferred to other nodes in the node resource pool.

In order to balance the load of each node in the node resource pool, the user terminal in the node with higher load can be transferred to the node with lower load. However, if the transfer of the user terminal is too frequent, the workload of the LCDN is too large. And it is not necessary to transfer the load between nodes with small load differences. Therefore, the transition threshold can be set in the LCDN. The difference between the load level of the node with the highest load and the load level of the node with the lowest load is greater than or equal to the setting. When the threshold is shifted, that is, when the difference between the highest load level and the lowest load level is greater than or equal to the set transition threshold, the LCDN starts to transfer the user terminal in the node with the highest load to the node with the lower load, and the user is determined according to the determined selection probability. The terminal selects a service node.

The various implementation processes described in the present invention can be applied to various node resource pools, for example, a CN node pool in the Global System for Mobile Communications (UMTS), or a Mobility Management Entity (MME) node in a SAE/LTE evolved network. Pool and User Data Surface Entity (UPE) node pool. The user terminal described above includes not only the user terminal device but also any network node that can be served by a node in the node resource pool.

In summary, the above description is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

Claims

Claim

A method for selecting a service node according to a load condition, wherein each node in the node resource pool divides the load level according to the load, and one load corresponds to a load level, and the current load of each node corresponds to a load level. The method includes the following steps:

A. The load control decision node LCDN obtains the load level of each node in the node resource pool;

B. The LCDN determines a selection probability corresponding to each node according to a load level of each node;

2. The method according to claim 1, wherein the step A further comprises:

The AO, the node in the node resource pool sends a load information message carrying the current load level of the node to the LCDN.

3. The method according to claim 2, wherein the step AO further comprises:

AO 1, LCDN sends a load information request to a node in the node resource pool.

4. The method of claim 3, wherein

The LCDN performs the step A01 at the same time, and further includes: the LCDN starts the load request timer, and waits to receive the load information message sent by the node in the step AO,

If the LCDN receives the load information message sent by the node in step AO before the load request timer expires, the load request timer is stopped;

If the load request timer expires and the LCDN does not receive the load information message sent by the node in step AO, the LCDN sends a load information request to the node in step AO again.

The method according to claim 3 or 4, wherein the load information request carries an LCDN identifier for identifying the LCDN.

The method according to claim 2 or 3, wherein the step AO further comprises: the LCDN returning a load information response to the node in the step AO.

7. The method of claim 6 wherein:

While the node performs the step AO, the method further includes: the node starting the load response timer, and waiting to receive the load information response returned by the LCDN,

If the node receives the load information response returned by the LCDN before the load response timer expires, the load response timer is stopped;

If the load response timer expires and the node does not receive the load information response returned by the LCDN, the node again sends a load information message carrying the current load level of the node to the LCDN.

The method according to claim 2, wherein the load information message further carries: a node identifier, or a new node indication for identifying whether the node is a newly added node in the node resource pool, or Indicates whether the node needs O&M indication for operation and maintenance, or any combination of the above.

The method according to claim 8, wherein when the load information message carries an indication of 0, the load information message further carries: a time interval, which is used to indicate that the load information message is sent to be executed. The time interval between maintenance operations.

The method according to claim 2, wherein the step AO further comprises:

A02. The node in the node resource pool detects that the load level of the node changes.

11. The method of claim 10, wherein

When the node performs the step A02, the method further includes: starting a load timer, and after the load timer expires, the step A0 further includes:

A021: The node determines whether it needs to send a load information message to the LCDN. If yes, step A0 is performed; otherwise, the load information message is not sent to the LCDN, and the flow of the present invention is ended.

12. The method of claim 11 wherein said step A021 is: The node first determines whether the current load level is the same as the load level when the load timer is started. If the current load level is the same as the load level when the load timer is started, step AO is performed; if the current load level is the load when the load timer is started The level is not the same, and it is determined whether the current load level is the same as the load level before the load timer is started. If the same, the node does not send a load information message to the LCDN, and ends the process of the present invention; if not, the step AO is executed. ;

Or: the node determines whether the current load level is the same as the load level before starting the timer. If they are the same, the node does not send a load information message to the LCDN, and ends the process of the present invention; if not, step A0 is performed.

13. The method according to claim 1, wherein the step B comprises the following steps:

14. The method of claim 13 wherein:

The node resource pool includes m nodes. The higher the load level of the node, the larger the current load of the node.

The execution number in the step B1 is: LCDN sorts each node in the node resource pool in the order of increasing or decreasing the load level according to the load level corresponding to the node, and writes the sequence number;

The step B2 is: LCDN divides the load level of each node by the accumulated result obtained in step B1, takes the result of the division as the intermediate probability of each node, and then sets the sum of all the node numbers to two nodes of m+1. The intermediate probability is interchanged, and the LCDN uses the intermediate probability after the interchange as the final selection probability of each node.

The method according to claim 14, wherein an overload threshold is set in the LCDN, and the LCDN sets a selection probability of a node whose load level is greater than or equal to an overload threshold to 0, and the m nodes do not include a load level greater than or A node equal to the overload threshold.

16. The method according to claim 1, wherein if there are k load levels, one load level represents a 1/k load of the node full load, and the load level of the node increases to indicate the load of the node. Increase.

17. The method of claim 13 wherein:

The node resource pool includes m nodes. The higher the load level of the node, the smaller the current load of the node.

The execution number in the step B1 is: LCDN sorts each node in the node resource pool in the order of increasing or decreasing the load level according to the load level corresponding to the node, and writes the sequence number, and loads the load level of each node. Accumulate

The step B2 is: the LCDN divides the load level of each node by the accumulated result obtained in step B1, and uses the result of the division as the selection probability of each node.

The method according to claim 17, wherein an overload threshold is set in the LCDN, and the LCDN sets a selection probability of a node whose load level is not greater than an overload threshold to 0, and the m nodes do not include a load level not greater than an overload. The node of the threshold.

19. The method according to claim 1, wherein if there are k load levels, one load level represents a 1/k load of the node full load, and the load level of the node is increased to indicate the node The load P is low.

20. A method according to claim 14 or 17, characterized in that the LCDN randomly orders nodes of the same load level or sorts according to node processing power and capacity.

The method according to claim 14 or 17, wherein the LCDN directly sets the selection probability of the node that needs to be operated and maintained to 0, and the m nodes do not include the node in the node resource pool that needs to be operated and maintained. .

The method according to claim 14 or 17, wherein when the node is newly added in the resource node pool, the method further comprises: the LCDN setting the selection probability of the newly added node to the maximum selection probability in the original node, Or setting the selection probability of the newly added node to a value greater than the maximum selection probability in the original node, and assigning the remaining selection probability to each original node according to the step B1 and the step B2, where the remaining selection probability is 1 and new Increase the difference in the selection probability of the node.

The method according to claim 22, wherein the setting of the selection probability of the newly added node to be greater than the maximum selection probability in the original node is:

The LCDN sets a weighting coefficient. If the weighting coefficient is a decimal, the selection probability of the newly added node is 1 and the product of the sum of the decimal and the maximum selection probability in the original node. If the weighting coefficient is an integer, 1 and the integer And the result of dividing the integer, the product of the maximum selection probability in the original node; or the fixed probability in the LCDN, the selection probability of the newly added node is the sum of the maximum selection probability and the fixed probability in the original node.

The method according to claim 1, 13, 14, or 17, wherein the node resource pool includes m nodes, and the step C further includes: the LCDN determines the selected probability, at 0 to The range of 1 is divided into m intervals, the interval corresponds to the node, and the length of each interval corresponds to the selection probability of the node;

The step C is: the LCDN generates a random fraction, determines the interval to which the random fraction belongs, and selects a node corresponding to the interval as the service node of the user terminal.

25. The method according to claim 1, wherein a transition threshold is set in the LCDN, the method further comprising: when the difference between the highest load level and the lowest load level is greater than or equal to the set transition threshold, the LCDN will load the node with the highest load. A part of the user terminals are transferred to the node with a lower load, and the step C is performed.