CN102438287B - Method for shutting off cells - Google Patents

Abstract

The present invention provides a method for shutting down a cell. The method limits the covered cell to accept other capacity during the time period from receiving a handover request sent by a capacity boosting cell to receiving a dormancy notification message sent by the cell. Upgrading the handover request used by the cell for cell shutdown can avoid the problem of shutdown failure caused by simultaneous shutdown of multiple cells.

Description

A method of shutting down a cell

technical field

The invention relates to cell management technology in a mobile communication system, in particular to a method for shutting down a cell.

Background technique

In the existing energy saving (Energy Saving, ES for short) mechanism, in order to realize energy saving, a specific mechanism may be adopted to turn off the radio frequency (RF) of some cells, so as to reduce wireless signal pollution. For example, during the day, the number of people in the office area increases and the business volume increases, while the number of people in the residential area decreases; the opposite is true at night. It is possible to turn off the RF of some residential areas during the day and turn it on again at night; and turn off the RF of some office areas at night and turn it on again during the day.

Currently, there are two commonly used ES mechanism application scenarios. One is the inter-RAT ES scenario. As shown in Figure 1, a seamless coverage network is composed of 2G and 3G cells A and B. The hotspots in the Regional deployment E-UTRAN cells C, D, E, F, and G are capacity-enhancing cells to increase system capacity and provide specific LTE services. The other is the evolved inter-NodeB (Inter-eNB) ES scenario, as shown in Figure 2, the coverage cell and the capacity enhancement cell are both E-UTRAN cells, cells A and B provide basic coverage, and cells C, D, and E , F, and G are capacity-enhancing cells arranged in hot spots.

In the ES mechanism, only capacity boost cells can be switched off/activated. The currently adopted signaling-based ES mechanisms are:

Shutting down the capacity-enhanced cell is judged based on the load. After the conditions are met, the users in this cell are switched to the coverage cell, and a configuration update message (sleep notification message) is sent to the neighboring base station to enter the dormant state.

The activation is judged by the coverage cell based on the load. After the condition is satisfied, an activation request is sent to the capacity enhancement cell. The capacity enhancement cell replies with an activation response and notifies other neighboring base stations with a configuration update message.

FIG. 3 is a schematic diagram of a simple network applying the ES mechanism. In FIG. 3 , Cell 1 is a coverage cell, and Cell 2 and Cell 3 are capacity enhancement cells. The following uses FIG. 3 as an example to describe the specific implementation of the current ES mechanism.

The shutdown process of Cell 2 is shown in Figure 4, which mainly includes: Cell 2 judges whether to shut down according to its own load and that of Cell 1, and starts ES after the following conditions are met.

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; L</span>}\\ \mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; h</span>}\end{array}\right.$

Among them, Load i is the load of cell i, L is the minimum load threshold of the cell, and H is the reactivation load threshold.

According to the above conditions, when the load of cell 2 is lower than the threshold L, and the reactivation condition H is not satisfied when it switches the load to cell 1, it will be shut down, that is, it will decide to enter the dormant state, and then send the reason to cell 1 by " Prepare to switch off" (switch off ongoing) handover request, switch the users in cell 2 to cell 1, notify cell 1 to enter the dormant state after the handover is completed, and enter the dormant state.

The activation process of cell 2 is shown in Figure 5. The activation process mainly includes: cell 1 decides to activate cell 2 according to the monitored load information, notifies cell 2 of activation, cell 2 enters the activation state according to the notification, and sends an activation message to cell 1. Community response.

Using the above-mentioned ES solution, when multiple capacity enhancement cells are shut down at the same time, ES failure may occur, which in turn leads to user ping-pong handover. As shown in Figure 3, it is assumed that cell 2 and cell 3 both meet the shutdown conditions, that is:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; L</span>}\\ \mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; h</span>}\end{array}\right.$

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; L</span>}\\ \mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; h</span>}\end{array}\right.$

Then the two cells hand over users to cell 1 successively, and enter the shutdown state. However, after both cell 2 and cell 3 switch the load to cell 1, the load of cell 1 may meet the activation condition again, that is:

Load1+Load2+Load3＞H

Then when cell 2 and cell 3 are shut down, cell 1 has to restart the activation process, which results in the failure of shutting down and the ping-pong handover of users.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for shutting down a cell, which can avoid the problem of shutting down failure caused by simultaneous shutting down of multiple cells.

In order to achieve the above object, the technical scheme proposed by the present invention is:

A method for shutting down a cell, the method comprising the following steps:

When the capacity boosting cell judges that the cell needs to be shut down and the users in the cell are switched to the coverage cell, a handover request is sent to the coverage cell because the reason is preparation for shutdown;

When the coverage cell receives the handover request, it judges whether it is currently in the energy saving stage;

If it is in the energy saving stage, the coverage cell notifies the capacity improvement cell that sent the handover request that the handover request is rejected, and the capacity improvement cell restarts after a preset time T when receiving the notification. Trigger the decision to shut down the cell and related processing procedures;

If it is not in the energy saving stage, the coverage cell sends a handover request response message to the capacity enhancement cell that sent the handover request, and the capacity enhancement cell continues to complete user handover in the cell and The corresponding sleep process;

The energy saving stage includes the time period from when the covered cell receives a handover request whose reason is to prepare for shutting down to when it receives a dormancy notification message from the capacity improvement cell sending the handover request.

To sum up, the method for shutting down the cell proposed by the present invention limits the coverage cell to accept other The capacity boosting cell is used for the handover request for cell shutdown, which can avoid the problem of shutdown failure caused by simultaneous shutdown of multiple cells.

Description of drawings

Figure 1 shows the inter-RAT ES scenario;

Figure 2 is an inter-eNB ES scenario;

FIG. 3 is a schematic diagram of an existing simple network applying the ES mechanism;

FIG. 4 is a schematic diagram of an existing cell shutdown process;

FIG. 5 is a schematic diagram of an existing cell activation process;

Fig. 6 is a schematic flow diagram of the main process of the present invention;

FIG. 7 is a schematic flowchart of Embodiment 1 of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The core idea of the present invention is: when a cell with a capacity boost is turned off, define the time period from when the covered cell receives the handover request to when it receives the dormancy notification message sent by the cell sending the handover request as the energy saving stage, In this energy saving stage, the covered cell cannot accept the switch off request from other cells, that is, when it receives another handover request from another cell with the reason of "switch offongoing", it should reject the request. Rejected cells need to wait for a period of time before triggering shutdown. In this way, multiple cells can be prevented from being shut down at the same time, so that the problem of failure to shut down caused by simultaneous shutoff can also be avoided.

Fig. 6 is a schematic diagram of the main flow of the present invention. As shown in Figure 6, the method for shutting down the cell of the present invention mainly includes the following steps:

Step 601. When the capacity enhancement cell decides that the cell needs to be shut down and the users in the cell are handed over to the coverage cell, a handover request is sent to the coverage cell because the reason is preparation for shutdown.

Specifically, this step can be implemented by using a method in an existing system, which will not be repeated here.

It should be noted that, in practical applications, if the capacity enhancement cell decides that the cell needs to be shut down, but there are currently no users in the cell, the process of shutting down the cell does not need to perform user handover, and directly sends a dormancy notification and enters the The dormant state is enough. In this way, since there is no need for user handover, there will be no problem of failure to shut down when shutting down the cell at the same time as other capacity-enhancing cells.

Step 602. When the covered cell receives the handover request, it judges whether it is currently in the energy saving stage.

The energy saving stage includes a time period from when the covered cell receives a handover request whose reason is to prepare for shutdown to when it receives a dormancy notification message sent by the capacity improvement cell that sent the handover request.

Here, through the above energy saving stage, it is ensured that when the covered cell handles all user handovers of a capacity-improved cell, only the user handover of the capacity-improved cell is processed. In this way, the problem of shutdown failure caused by simultaneous shutdown of multiple cells can be effectively avoided.

Furthermore, in order to prevent other cells from being unable to perform ES due to some reasons that the capacity upgrading cell does not continue the ES process, a waiting threshold can be set. Waiting for the threshold, the energy saving phase ends.

In order to achieve the above purpose, specifically, the energy saving stage may further include: starting from receiving a handover request whose reason is that the covered cell is ready to be shut down, and then reaching a preset waiting threshold but not receiving the request to send the The time period until the capacity of the handover request is boosted by the dormancy notification message sent by the cell.

The setting of the waiting threshold should be greater than the time required for a cell to complete all user handovers. Specifically, a person skilled in the art can set an appropriate value through simulation according to an actual application scenario.

Step 603: If it is in the energy saving stage, the coverage cell notifies the capacity improvement cell that sent the handover request that the handover request is rejected, and the capacity improvement cell has a preset time T since receiving the notification. After that, the decision to shut down the cell and related processing procedures are retriggered.

In this step, when the covered cell is in the energy saving stage, reject the handover request of other capacity boosting cells for shutting down, that is, implicitly reject the shutting down request, and notify other capacity boosting cells that send the handover request that their handover request is rejected , the rejected cell can re-trigger the judgment and processing flow of shutting down the cell after a period of time. In this way, many problems caused by simultaneous shutdown of two capacity enhancement cells can be effectively avoided.

Here, the capacity enhancement cell whose handover is rejected needs to wait for a time T before re-triggering the judgment and processing process of shutting down the cell, so as to avoid the shutdown failure problem of the existing system.

For this time T, if it is set too small, the cells that are being shut down will not be able to complete the handover of all users, which will cause the rejected cells to frequently send handover requests, resulting in waste of signaling resources. In order to improve the capacity The cell understands the resource status change after the coverage cell accepts users from other cells. T should be at least longer than the period of resource status reporting by the coverage cell; otherwise, if it is set too large, it will cause other requests to shut down the cell waiting time Long, affecting the effect of cell shutdown, thereby reducing system performance. In practical applications, those skilled in the art can determine an appropriate value through simulation that can ensure that all user handovers in the current shutdown cell are completed according to the actual application scenario.

Specifically, the judgment and related processing procedures for shutting down the cell are the same as those of the existing system, including:

The capacity boosting cell judges whether the preset shutdown condition is currently met, and if the shutdown condition is not met, then exit the method, and if the shutdown condition is met, then judge whether the current number of users in the cell is zero , if the number of users is zero, send a dormancy notification message to the covered cell and enter a dormant state, and if the number of users is not zero, send a handover request to the covered cell because the reason is preparation for shutdown.

Here, the coverage cell may notify the handover request by sending a handover preparation failure message whose reason is "No Radio Resources Available in Target Cell" to the capacity boosting cell that sends the handover request be rejected.

Step 604: If not in the energy saving stage, the coverage cell sends a handover request response message to the capacity enhancement cell that sent the handover request, and the capacity enhancement cell continues to complete the cell according to the handover request response message User switching and the corresponding hibernation process.

In this step, when the covered cell is not currently in the energy saving stage, the same as the existing system, continue to complete the process of shutting down the capacity improvement cell that sends the handover request. The specific implementation method of this step is known to those skilled in the art and will not be repeated here.

Embodiment 1 of the present invention will take the scene shown in FIG. 3 as an example to describe the specific implementation of the present invention in detail. In this scenario, cell 2 and cell 3 are active.

Fig. 7 is a schematic flow diagram of the main process of this embodiment. As shown in Figure 7, this embodiment includes:

Steps 701-702, cell 2 meets the shutdown condition, and sends a handover request to cell 1;

Step 703, cell 1 sends a handover request response to cell 2;

Step 704, Cell 2 handovers other users to Cell 1;

Steps 705-706, cell 2 sends a dormancy notification message to cell 1, notifying to enter the dormant state, and then cell 2 enters the dormant state;

In steps 707-708, cell 1 is in the ES stage from receiving the handover request to receiving the dormancy notification message. At this stage, cell 3 also meets the shutdown condition, and sends a handover request to cell 1, and cell 1 sends to cell 3 a handover preparation failure message whose reason is "No Radio Resources Available in Target Cell";

Steps 709-710, cell 3 judges again after waiting for a period of time, and sends a handover request to cell 1 if the shutdown condition is still met;

Step 711, at this time cell 1 has finished the ES phase, and sends a handover request response to cell 3;

Step 712, cell 3 switches other users to cell 1;

In steps 713-714, cell 3 sends a dormancy notification message to cell 1, notifying the cell 1 of entering the dormancy state, and then cell 3 enters the dormancy state.

In the above process, the processing of cell 1 (coverage cell) specifically includes the following steps:

The coverage cell saves the variable "ES cell", which is set to invalid during initialization. This variable is used to record the ES stage and the cell that triggers ES;

When receiving the switching request message, if the switching reason is "switch off ongoing" and the "ES cell" variable is invalid, it is considered to have entered the ES stage, and the "ES cell" variable is assigned to the cell that sent the switching request, and at the same time, it starts Timer _TES ;

Afterwards, when a switch request message is received, if the switch reason is "switch off ongoing" and the "ES cell" variable is valid, it is considered that the two cells will be switched off at the same time. In order to avoid this situation, the switch needs to be rejected ask;

When receiving the dormancy notification message from the "ES cell", it is considered that the ES phase is over. Set the "ES Cell" variable to invalid, and stop T _ES .

In the above process, T _ES defines the maximum time of the ES process. Its function is to prevent the cell that initiates ES from not continuing the ES process for some reason, causing other cells to be unable to perform ES. When T _ES times out, the "ES cell" variable should be set to deactivated.

The method to increase the capacity of the cells (cells 2 and 3) is as follows:

The capacity boosting cell judges whether the preset shutdown condition is currently met; if the shutdown condition is not met, exit; if the shutdown condition is met, then judge whether the current number of users in the cell is zero; if the user number is zero, then send a dormancy notification message to the covered cell, and enter the dormant state; if the number of users is not zero, then send a handover request that the reason is to be turned off to the covered cell, and then if the reason is received Prepare the failure message for the handover of "No Radio Resources Available in TargetCell", then wait for T and then turn to the step of judging whether the preset shutdown conditions are met, otherwise continue to process according to the existing method to complete the subsequent shutdown of the cell process.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. a method for shutting off cells, is characterized in that, the method comprises the following steps:

In the time that capacity lifting community judgement need to be turn-offed this community and this community user is switched to coverage cell, sending reason to described coverage cell is to prepare the handover request of shutoff;

When described handover request is received in described coverage cell, judge current whether in the energy saving stage;

If in the described energy saving stage, described in the capacity lifting community of the described handover request of described coverage cell notice transmission, handover request is rejected, described capacity promotes after the preset time T of community in the time receiving described notice, again triggers judgement and the correlation procedure of turn-offing this community;

If not in the described energy saving stage, described coverage cell promotes community to the capacity that sends described handover request and sends handover request ack message, described capacity promotes community according to described handover request ack message, has continued the switching of this community user and corresponding sleep procedure;

The described energy saving stage comprises that coverage cell is from receiving that a reason is the handover request of preparing to turn-off, to the time period of receiving in the dormancy notification message of the capacity lifting community that sends this handover request;

Judgement and the correlation procedure of this community of described shutoff comprise:

Described capacity promotes community and judges the current default turn-off criterion that whether meets, if do not meet described turn-off criterion, exit described method, if meet described turn-off criterion, judge whether the current number of users in this community is zero, if described number of users is zero, send dormancy notification message to described coverage cell, and enter resting state, if described number of users is non-vanishing, sending reason to described coverage cell is to prepare the handover request of shutoff.

2. method according to claim 1, it is characterized in that, the described energy saving stage further comprises: coverage cell is from receiving that a reason is the handover request of preparing to turn-off, and does not receive the time period in the dormancy notification message of the capacity lifting community that sends this handover request till time span after this reaches default wait threshold value.

3. method according to claim 1, it is characterized in that, described coverage cell, by promoting community to the capacity that sends described handover request, sends the former switching preparation failed message that there is no available Radio Resource because of Target cell, notifies described handover request to be rejected.