KR20150145362A - Method and apparatus for operating cell for energy saving - Google Patents

Abstract

A mobile communications system operating method comprises of: determining that the system is in a state needing a progress to an energy saving (ES) mode, when a measured cell load amount is equivalent to or less than a predetermined first critical value; setting and performing D2D direct communications for a terminal capable of performing device to device (D2D) communications in traffics serviced in a cell; performing handover to a master cell for terminals in which D2D communications are not possible; measuring cell load amount after the inter-cellular handover is performed; and performing switch-off, when the measured cell load amount reaches a predetermined second critical value.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a cell for energy saving,

The present invention relates to a method and apparatus for operating a cell, and more particularly, to a method and apparatus for operating a cell for energy saving.

The information and communication technology (ICT) industry, which accounts for about 2% of the world's carbon emissions, is moving toward anticipation of explosion of data traffic in existing voice data transmission, A greater amount of energy consumption is required than before. As a result, energy efficiency is more urgent than any industrial sector.

In the next generation mobile communication system, not only a device to device (D2D) in which a person and a person communicate with each other, but also a machine to machine (MTH) for communicating equipment and a person or a machine to machine (MTM) Machine to Communication) are expected to be built and utilized. D2D terminals are triggered when an event or situation satisfying a given condition occurs in a specific environment, and D2D communication is established between the terminals. Therefore, signaling and traffic congestion are incomparably incomparable with communication between existing UEs (user equipment). As a result, the system is overloaded and power consumption is expected to increase rapidly.

Especially, in the wireless mobile communication industry, existing voice communication service-based systems such as LTE (Long Term Evolution) and LTE-A (LTE-Advanced) systems are increasing in capacity and suitable for high speed / It is evolving. As a result, the use of smartphones and smart TVs will increase, and traffic volume is expected to increase more than 1,000 times compared to the current level by about 2015, which will result in enormous energy consumption and global environmental destruction caused by carbon emissions .

As mentioned above, ICT industry is the most urgent area to increase energy efficiency throughout the industry at present. Conversely, ICT technology is also attracting attention as a technology that can reduce carbon emissions in other industries.

In order to increase the energy efficiency, an ES (Energy Saving) management method is used. When each cell performs switch-off in order to enter the ES mode while mutually exchanging information, All subscribers in service in the cell are forced to perform handover to a neighboring specific cell in order to ensure continuity of service. At this time, in order to perform the procedure for performing the handover, the signaling is simultaneously transmitted and received. In order to guarantee the traffic, a large amount of traffic is instantly generated in the cells accommodated by the handover, of service can not be guaranteed.

In addition, HC (Hole Coverage), which is a phenomenon in which the UE is placed in a state in which it can not access any cell, occurs when a specific cell is turned off for a service traffic in a border region around the cell, The problem can not be solved. In order to solve this problem, there have been proposed techniques for solving the HC problem that can occur in the cell boundary region by extending the cell radius of the cell centered by the ES compensation. However, this technique can compensate for the service continuity, but the ES compensating cell must increase the transmit power in order to increase the cell radius. This poses a problem of reducing the ES efficiency of the base station, since it provides a cause for the base station to consume a lot of energy.

A problem to be solved by the present invention is to provide a cell operating method and apparatus for reducing energy in a mobile communication system.

According to an aspect of the present invention, there is provided a method of operating a cell in a mobile communication system, the method comprising: measuring a cell load; and when the measured cell load is equal to or less than a predetermined first threshold, determining an energy saving mode; Establishing and performing D2D direct communication for a terminal capable of D2D (device to device) communication among traffic in service in a cell; Performing inter-cell handover to a master cell for terminals that are not capable of D2D communication; And measuring a cell load after performing the inter-cell handover, and performing switch-off when the measured cell load reaches a preset second threshold.

According to the embodiment of the present invention, when the traffic load distribution is below a certain threshold value, the service is continuously maintained through the direct communication procedure for the traffic that can be directly communicated among the traffic in service in the base station, I can not. Therefore, it is possible to prevent an increase in signaling occurring at the time of performing the handover and congestion of the instantaneous increase in traffic, and to minimize the power consumption of the base station.

Particularly, by reducing the cell power through D2D communication, the threshold of power saving through switch-off of the base station cell is set to be low, thereby increasing the probability that the base station cell can be switched off as much as possible. You can keep your time long.

In addition to the D2D communication for the traffic in service, cell radius extension and handover are performed to prevent system service quality (QoS) degradation due to signaling and traffic congestion of the entire system in advance, And maximize power consumption efficiency, thereby improving system performance as a whole.

1 is a diagram illustrating a configuration of a mobile communication network according to an embodiment of the present invention.
2 is a conceptual diagram illustrating a cell operating method according to an embodiment of the present invention.
3 is a flowchart of a method of operating a cell according to an embodiment of the present invention.
4 is a diagram illustrating a structure of a cell management apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

Hereinafter, a method and an apparatus for operating a cell according to an embodiment of the present invention will be described.

1 is a diagram illustrating a configuration of a mobile communication network according to an embodiment of the present invention.

1, the base station 1 transmits a downlink signal to a plurality of terminals 2 and receives an uplink signal from each of the terminals. In the device-to-device (D2D) environment using the LTE-Advanced, each terminal, that is, the D2D terminal 2 receives the downlink signal of the base station 1 and transmits the uplink signal.

Also, the terminal 2 can exchange D2D signals between the terminals, one-to-one communication can be performed between the terminal and the terminal, and one-to-many communication can be performed between one terminal and a plurality of terminals.

In order to provide a high-speed broadband mobile multimedia packet service with a high data rate, a low latency, and a packet-optimized wireless access technology at an inexpensive use rate, The mobile communication system according to the example may be a communication system capable of high-speed data transmission and capable of IP-based services.

In this mobile communication system, because it operates in the overlapping cell environment of HetNet (Heterogeneous Networks), information exchange between cells of different systems or the same system in terms of power saving, Perform a method of operation that can be saved.

2 is a conceptual diagram illustrating a cell operating method according to an embodiment of the present invention.

2, in an overlapping cell environment, the base station installation between network operators exponentially increases in order to provide a service unique to each communication operator, so that the energy of information and communication technology (ICT) The usage amount, that is, the power consumption may increase sharply. In the embodiment of the present invention, an energy saving (ES) -based cell operation is performed in order to save energy.

The determination as to whether or not to enter the ES mode in each cell is based on a preset threshold value, which is set in advance considering various factors and can be named "H-threshold ". It is judged that the system should enter the ES mode when the load due to the signal or traffic of the system becomes the H-threshold. In order to maximize the ES efficiency of the mobile communication system and guarantee the continuity of services, to improve the system performance and to minimize the power consumption of the system, the handover is not forcibly performed for the terminal in service in the existing cell, To ensure the continuity of service by maximizing the advantage of direct communication without using wired resources for terminals capable of D2D (device to device) communication. ES mode, it is determined whether or not there is a terminal capable of D2D communication, and the D2D communication is allowed to be performed first for a traffic service capable of D2D communication. Accordingly, the service disconnection problem that may occur due to the small received signal strength at the time of handover can be improved for the service traffic in the cell boundary region.

 ES mode, it is essential that switch-off-switch-off of any cell indicates that the service is stopped and the terminals that have been served are forcibly handed over to another cell. In this case, there should be no problem with the coverage hole (CH), so there must be a surrounding cell that can cover it, or the coverage of the same rank cell should be extended. In order to extend the coverage of the cell of the same rank, several cells of the same rank are designated as one group and a master cell among the cells included in the group is preset in advance as shown in FIG. The master cell represents a cell that can expand the cell coverage and control the coverage of the remaining cells when entering the ES mode. When the master cell enters the ES mode, the master cell must expand the cell considering the traffic state or load of the neighboring cells, and control the area of the neighboring cell.

For traffic that can not communicate with D2D, control is firstly performed to perform handover to cells with less signaling. At this time, handover between cells is performed by performing handover between master cells that have extended cell coverage by designating in advance, ensuring continuity of service, and can be generated when performing inter-system handover that may occur in an existing overlapping cell environment Which mitigates instantaneous signaling increases and traffic overload. Through this process, the effect of setting the load according to the signaling and the traffic to be set to be smaller than the H-threshold for entering the ES mode is caused, thereby increasing the probability of entering the ES mode, The efficiency can be increased.

Since power consumption through D2D communication is considerably less than power consumption generated by operating the base station cell, it is preferable to perform D2D communication as much as possible in terms of energy optimization operation of the mobile communication system, , It is effective enough not to be compared in terms of saving power consumption. Therefore, if possible, D2D communication is performed for terminals capable of direct communication.

Performing handover between systems increases the signaling complexity and traffic complexity. Therefore, in the embodiment of the present invention, when the traffic load distribution reaches the preset H-threshold, it is determined whether the service traffic in the system is capable of direct communication, and if possible, the service continuity is maintained through the D2D communication procedure. To extend the coverage of the pre-established master cell so that there is no CH due to cell switch-off, and to ensure continuity of service, handover between cells is easier than handover between systems. Accordingly, it is possible to prevent signaling and traffic congestion which occur when a handover between systems is performed, in advance.

D2D communication, and then performs inter-cell handover between the master cells, and then determines whether to perform switch-off. At this time, other thresholds may be used, which may be referred to as "L-threshold ". The L-threshold value may be set in advance by the operators in accordance with the communication environment from the viewpoint of system operation. Here, the L-threshold value is set to be smaller than the H-threshold value. When the load of the cell reaches the L-threshold, that is, when the load of the cell which has reached the H-threshold drops to the L-threshold, the cell switches off . Then, the cell finally goes to the switch-off state and completely performs the ES algorithm according to the embodiment of the present invention. If the load of the cell does not reach the L-threshold, the procedure according to the embodiment of the present invention is repeatedly performed to continuously judge whether or not the condition for entering the switch-off state is satisfied.

Hereinafter, a method of operating a cell according to an embodiment of the present invention will be described in more detail with reference to the above description.

3 is a flowchart of a method of operating a cell according to an embodiment of the present invention.

First, the cell operating device 1 periodically checks the load of the cell (S100). Here, it is possible to use various parameters as a parameter for determining the load of the cell. The quality of service (QoS), the number of terminals in service, the amount of wired resources used for services, the amount of wireless resources used, the bit error rate (BER) (Block Error Rate), transmitted signal strength, received signal strength, remaining power of the terminal, and the like. In the embodiment of the present invention, the cell load is measured in consideration of at least one parameter among the above plurality of parameters for determining the cell load.

The cell operating device 1 measures the cell load and compares it with a preset threshold (S110). In an embodiment of the present invention, the threshold is an H-threshold, which is a first threshold, and an L-threshold, which is a second threshold. The H-threshold is a minimum threshold for determining whether the load of the system can enter the ES mode performing procedure. If the load is less than the H-threshold, the D2D communication according to the embodiment of the present invention and the ES algorithm through cell expansion are performed . The L-threshold value is a threshold value for judging whether or not switch of the corresponding cell is finally possible after performing the ES algorithm. The L-threshold is set to be smaller than the H-threshold. The thresholds according to the embodiment of the present invention may be set so as to sufficiently achieve power saving of the base station cell by performing switch-off of the base station cell at least because the service in use is insufficient. Otherwise, if the base station cell is switched on again after switching it off, it takes time for the initialization process to operate normally, which may lead to overloading to other cells, which may lead to QoS degradation.

As described above, the cell operating device 1 measures the cell load and first compares it with the first threshold, the H-threshold. If the cell load direction falls below the H-threshold, it is determined that the ES mode should be entered.

Before entering the ES mode, the cell operating device 1 confirms whether there is a terminal capable of D2D communication among traffic in service in the cell, and acquires information about the terminal (S120). Information on the service traffic can be stored in an OAM (Operation, Administration, Maintenance) or a specific database (DB) in a cell, and obtains information on terminals capable of D2D communication based on such information. That is, terminal information and position information capable of D2D communication and state information of neighboring cells are acquired.

Based on the information on the terminals capable of D2D communication, the cell operating device 1 starts a procedure for direct communication between terminals capable of D2D communication, requests a terminal capable of D2D communication to set up a call for direct communication (S130, S140) and completes the procedure for direct communication with all terminals capable of D2D communication. At this time, the D2D communication terminal may terminate the D2D communication traffic with the neighboring cell for the minimum information to be transmitted and received, and may maintain the signal channel so that the communication environment change information of the cell can be exchanged. In general, since direct communication performs communication between terminals without going through a base station or a cell, the load of a signal only affects an existing cell when direct communication is established. However, when the traffic setting is completed, the base station does not go through the base station. I will not be involved. Therefore, as the number of terminals capable of direct communication increases, D2D communication is performed, and the amount of resources of the base station is reduced. The decrease in the resource usage of the base station is reflected in the H-threshold for determining the ES mode for power saving of the base station, which can increase the possibility of switching off the base station.

When the procedure for direct communication is completed for all terminals capable of communicating with the D2D, the cell operating apparatus 1 performs handover between cells with respect to traffic for which D2D communication is not possible, in order to prevent the HC from being switched off . To this end, the coverage of a pre-designated master cell is expanded, and a handover between the cells, which is easier to process and traffic than inter-system handover, is performed to ensure continuity of services. Specifically, the cell operating device 1 determines whether the coverage expansion of the master cell is possible (S150). If the expansion is possible, the cell operating device 1 requests the coverage area to the master cell (S160). For the traffic that can not be D2D communicated, handover between cells is performed (S170). That is, the terminal related to the traffic requests handover to the master cell and provides the traffic related information to the master cell. In this manner, according to the handover between cells, it is possible to prevent signaling and traffic congestion which occur when handover between systems is performed.

The cell operating device 1 performs inter-cell handover between the D2D communication and the master cell, and then determines whether or not it can perform switch-off with respect to its own cell. To this end, the current cell load is compared with a preset L-threshold (S180). The L-threshold value can be defined in advance according to the communication environment in terms of system operation, and it should be set smaller than the H-threshold value.

As a result of the comparison, when the current cell load drops to reach the L-threshold (when the cell load is below the L-threshold), it is determined that the cell must be switched off. In this case, it is notified to the operator operation information such as the OAM that the switch-off state is entered, and the state is recorded. The cell operating device 1 operates in a switch-off state when the cell load falls to the L- threshold value, and the ES algorithm according to the embodiment of the present invention is performed (S190).

If the cell load does not reach the L-threshold, the cell operating device 1 repeatedly performs the above-described procedures (S100 to S180) to determine whether the condition for entering the switch-off state at any time is the cell load and the H- And an L-threshold value, and performs a cell operation method according to an embodiment of the present invention.

According to the embodiment of the present invention, by performing cell power saving through direct communication according to the cell load, a traffic threshold value (L-threshold) for power saving for switching off the base station cell is numerically set to be high Effect occurs. Therefore, not only the probability of going to the switch-off state of the base station cell is raised, but also the switch-off time of the base station cell is maintained for a long time, thereby effectively increasing the power saving of the base station cell of the mobile communication system. .

4 is a diagram illustrating a structure of a cell management apparatus according to an embodiment of the present invention.

4, the cell operating apparatus 1 according to the embodiment of the present invention includes a cell load measurement unit 10, a D2D communication terminal information acquisition unit 20, a D2D communication request unit 30, A coverage extension unit 40, an inter-cell handover performing unit 50, a switch-off performing unit 60, and an energy saving control unit 70.

The cell load measuring section 10 measures the load of the cell. It can be periodically measured in accordance with a preset period. Parameters for cell load measurement include quality of service (QoS), number of terminals in service, amount of wired resources used for service, amount of radio resources used, BER or BLER of transmission / reception data, At least one of the battery remaining amount is used.

The D2D communication terminal information obtaining unit 20 obtains information on a terminal capable of D2D communication among the traffic in service in the cell. The cell operating device 1 may include a database for managing information on traffic to be serviced, and terminal information, location information, and information on neighboring cells may be stored for each service traffic in the database. The D2D communication terminal information acquisition unit 20 can acquire information on a terminal capable of D2D communication or acquire such information from an OAM device from such a database of the cell operating device 1. [

The D2D communication requesting unit 30 requests a D2D-capable terminal to set up a call for direct communication based on the information on terminals capable of D2D communication, and performs a procedure for direct communication with all terminals capable of D2D communication The setting is completed.

The cell coverage extension unit 40 requests cell coverage extension with a predetermined master cell for processing of terminals that are not capable of D2D communication among traffic in service in the cell. At this time, it is possible to perform expansion of the coverage of the master cell after confirming that cell coverage expansion is possible.

The inter-cell handover performing unit 50 performs inter-cell handover to the terminal according to a request from the energy saving controller 70. [ Particularly, among the service traffic in the cell, the UEs which are not capable of D2D communication are requested to perform an inter-cell handover, thereby allowing the UEs to hand over to the master cell.

The switch-off performing unit 60 performs cell switch-off according to a request from the energy saving control unit 70. All subscribers in service in the cell perform inter-system handover to ensure continuity of service. The switch-off performing unit 60 can perform switch-off after notifying the OAM apparatus that the switch-off state is entered.

Meanwhile, the energy saving controller 70 performs an energy saving (ES) for minimizing the power consumption of the system, and includes an ES entry determiner 71 and a switch off determiner 72 for this purpose.

The ES entry determining unit 71 compares the cell load provided from the cell load measuring unit 10 with an H-threshold value, which is a preset first threshold value, to determine whether to perform the ES mode. When the cell load becomes the H-threshold or less, it is determined that the cell enters the ES mode. The D2D communication terminal information acquisition unit 20, the D2D communication request unit 30, the cell coverage extension unit 40, and the inter-cell handover performing unit 50, respectively, To perform the corresponding operation. Accordingly, terminals capable of D2D communication perform D2D communication among terminals in service in the cell, and terminals not capable of D2D communication perform inter-cell handover with a master cell.

The switch-off judging unit 72 compares the cell load provided from the cell load measuring unit 10 with the L-threshold value, which is a second preset threshold value, after the ES entering mode, and judges whether or not the switch-off is performed. When the cell load falls to the L-threshold, it is determined that switch-off is to be performed, and an operation command is output to the switch-off performing unit 60 so that switch-off is performed.

According to the embodiment of the present invention, by using the cell power saving through direct communication, the effect of making the traffic L-threshold value for power saving for switching off the base station cell numerically high occurs. Therefore, not only the probability of going to the switch-off state of the base station cell is increased, but also the switch-off time of the base station cell is maintained for a long time, thereby effectively reducing power consumption of the base station cell of the mobile communication system .

The embodiments of the present invention described above are not implemented only by the apparatus and method, but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (1)

In a method of operating a cell in a mobile communication system,
Measuring a cell load and determining a state in which an energy saving mode should be entered when the measured cell load is less than or equal to a preset first threshold;
Establishing and performing D2D direct communication for a terminal capable of D2D (device to device) communication among traffic in service in a cell;
Performing inter-cell handover to a master cell for terminals that are not capable of D2D communication; And
Measuring a cell load after performing the inter-cell handover, and performing switch-off when the measured cell load reaches a preset second threshold
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