KR20100064234A - Connection admission control method between bts - Google Patents

Abstract

PURPOSE: Only if CAC(Call Admission Control) of serving cell is failed, a method for controlling call admission between BSs(Base Stations) is provided to require load information to neighboring BSs, thereby reducing overhead according to information exchange with neighboring cells. CONSTITUTION: If a surplus resource does not exists in a serving BS or CNIR(Carrier-to-Noise and Interference Ratio) value of an MS(Mobile Station) is smaller or same with a critical value, the serving BS request load information to neighboring BS(S120,S130). The serving BS performs a call admission request after selecting a target BS(S140). If the surplus resource exists in the serving BS and the CNIR value of the MS satisfies the critical value, the serving BS permits a call admission of the MS.

Description

Connection admission control method between base stations

The present invention relates to a method for controlling call admission between base stations, and more particularly, in a mobile communication system in which information is directly exchanged between base stations, reducing overhead due to message exchange between base stations (eNB), The present invention relates to a base station call admission control method capable of improving performance.

In the existing third generation mobile communication network and the improved third generation mobile communication network, information is exchanged between the base station BTSs by relaying the base station controller BSC. In such a multi-cell environment, neighboring cells [Note; In general, a communication radius of a base station is referred to as a cell. Hereinafter, the base station and the cell will be described as having the same technical meaning. It is somewhat inefficient due to having to go through this base station controller.

Recently, 3GPP LTE (3GPP Long Term Evolution) system and LTE-Advanced system have been developed as a next generation mobile communication standard to compensate for the above problems. In the 3GPP LTE system and LTE-Advanced system, the base station is defined as an 'eNB (evolved NodeB)'.

Referring to FIG. 1, in the next generation mobile communication standard, the information exchange process between base stations is performed. The radio resource information between base stations is directly exchanged between base stations through an X2 interface without passing through a base station controller.

For example, in a multi-cell OFMDA system, when the frequency reuse rate is close to 1, the call acceptance success rate of the terminals located in the outer region decreases due to an increase in interference from neighboring cells.

This leads to a decrease in system capacity, and this problem is solved through continuous load information (excess RB and channel information) exchange and call acceptance requests with neighboring base stations.

However, in the prior art, in the load information collection of neighboring base stations, the overhead caused by the periodic resource status information request and response message exchange between base stations may have a problem that may act as a detrimental effect on the performance of the entire system.

Accordingly, there is a demand for a new method for improving the system performance by reducing the call acceptance probability of the terminal but reducing the overhead.

The technical problem to be achieved by the present invention, in a mobile communication system for the direct exchange of information between base stations, the base station between the base station (eNB) to reduce the overhead due to the exchange of messages, and can improve the performance of the call acceptance request between base stations It is to provide an admission control method.

The objects of the present invention are not limited to the above-mentioned objects, and other objects which are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, an inter-base station call admission control method according to an embodiment of the present invention, if a call acceptance request message is received from the terminal, identifying a surplus resource to determine whether there is a surplus resource in the serving base station; A threshold comparison step of comparing a carrier-to-noise and interference ratio (CNIR) measured by a terminal with a CNIR _threshold ; And a call accepting step of accepting a call of the terminal when a surplus resource exists in the serving base station and the CNIR is greater than the CNIR _threshold , wherein the step of accepting the call is independently performed without exchanging load information between the base stations. do.

According to an embodiment of the present invention, a call reception control method between base stations includes a load information request step in which the serving base station requests load information from neighboring base stations when a call acceptance request of a terminal fails; And selecting a target base station so as to correspond to load information received from neighboring base stations and requesting call acceptance of the terminal.

At this time, if there is a surplus resource in the target base station, and the CNIR value of the terminal is greater than the CNIR _threshold , it is preferable to allow the terminal to accept the call.

On the other hand, if there is no surplus resource in the target base station or if the CNIR value of the terminal is less than or equal to the CNIR _threshold , it is preferable to reject the call accept request.

In addition, if there is no surplus resource in the serving base station or if the CNIR value is less than or equal to the CNIR _threshold , it is preferable to reject the call accept request of the UE.

Here, the load information is the number of surplus resources and channel information, and the CNIR value is preferably measured through a pilot channel.

According to the call admission control method between base stations of the present invention as described above, there is an advantage that the success rate of call acceptance can be improved compared to the rock lock control (CAC) method that considers only the serving cell.

In addition, since the load information is requested from the neighbor base stations only when the failure control control (CAC) in the serving cell fails, there is an additional advantage of reducing the overhead due to information exchange with the neighbor cells.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various different forms, and the present embodiments merely make the disclosure of the present invention complete, and are common in the art to which the present invention pertains. It is provided to inform those skilled in the art to the fullest extent of the invention, the invention being defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating an embodiment of a mobile communication network to which the present invention is applied, and FIG. 2 is an explanatory diagram showing an independent call acceptance process in a serving base station according to an embodiment of the present invention.

As shown in Figure 1 and 2, the mobile communication network to which the present invention is applied includes a plurality of base stations (10, 11, 12) and a plurality of terminals (20).

Hereinafter, in describing the present invention, the terminal 20 requests a call acceptance to the base station of reference numeral '10' (hereinafter, the base station 10 is referred to as a 'serving base station'), and the call acceptance of the terminal 20 is made. For this purpose, load information is directly exchanged between the base station 10 and the other base stations 11 and 12.

Meanwhile, the system to which the present invention is applied may be a representative example such as 3GPP LTE (3GPP Long Term Evolution) system, LTE-Advanced system, etc., but it is obvious that the application environment of the present invention is not necessarily limited to such a system.

In the present invention, in order to reduce the overhead incurred when exchanging resource state information related messages between neighboring cells, an independent call acceptance is performed for each serving base station 10, and the serving base station 10 accepts the call. Only if this is not the case, the neighboring base stations 11 and 12 are requested to request a load status request message (Resource Status Request).

In addition, the present invention calculates a carrier-to-noise and interference ratio (CNIR) value of the terminal 20 requesting the call acceptance, and compares whether the result exceeds the required threshold (CNIR _threshold ) to determine whether to accept the call. do.

Prior to this, in the present invention, it is determined whether there is a surplus resource (Resource Block) in the serving base station 10 that receives the call accept request from the terminal 20.

For example, if the serving base station 10 receives the call acceptance request of the terminal 20, the surplus resources are calculated through the pilot channel, and the CNIR value of the terminal 20 is calculated, and conversely, if there is no surplus resources in the serving base station 10, Reject the call accept request of the terminal 20.

Subsequently, the CNIR value of the terminal 20 is subjected to a comparison process with the requested CNIR _threshold . At this time, if the CNIR value of the terminal 20 is greater than the CNIR _threshold , the serving base station 10 calls the terminal. Accept the request for acceptance. On the other hand, if the CNIR value of the terminal 20 is smaller than the threshold, the call accept request is rejected.

As such, call acceptance is allowed only when surplus resources exist in the serving base station 10 and the CNIR value of the terminal satisfies the required threshold (CNIR _threshold ). In this case, the serving base station 10 and the neighboring base station 11 may be selected. , 12) no exchange of messages related to resource status information occurs.

In other words, if the call accepting request of the terminal 20 is allowed in the serving base station 10, the exchange of channel state information with the neighbor base stations 11 and 12 is not necessary, so that the load information of the neighbor base stations 11 and 12 is not required. The request for is not made. As a result, the present invention can prevent the overload of the system due to unnecessary information exchange.

On the other hand, if the call reception request of the terminal 20 in the serving base station 10 fails, that is, the lack of surplus resources in the serving base station 10, or the CNIR value of the terminal requesting the call acceptance (CNIR _threshold ) If not satisfied and is rejected by the serving base station 10, the serving base station 10 requests the load information (surplus RB and channel information) of the neighboring base stations (11, 12).

3 is an explanatory diagram illustrating a process of requesting load information from neighboring base stations.

Referring to FIG. 3, when the call acceptance request fails, the serving base station 10 of the terminal 20 transmits a resource status request message to the neighboring base stations 11 and 12 through the X2 interface, The neighboring base stations (11, 12) receiving this will inform the serving base station 10 of its load information (resource RB and channel information) through load measurement response messages (Resource status response and Resource status update).

As such, the serving base station 10 receiving the load information from the neighbor base stations 11 and 12 may select the most suitable base station among the neighbor base stations 11 and 12 that satisfy the preliminary constraints (such as throughput or blocking rate) per cell as the target base station. Will be chosen.

The terminal 20 performs a call accept request to the selected target base station through the above process. In this case, the target base station receiving the call acceptance request measures the CNIR value of the call acceptance request terminal 20 and compares it with the CNIR _threshold as in the serving base station 10, and as a result, the CNIR value of the terminal exceeds the threshold. Allows the terminal to accept the call.

In addition, the present invention, if it is determined that the connection of the selected target base station is not possible, it is possible to request the radio resource control connection by reselecting the base station of the neighboring cell.

As such, the inter-base station call admission control method according to an embodiment of the present invention primarily performs independent call acceptance for each serving base station 10, and only when the call base station 10 does not accept the call. By exchanging the message related to the resource status information with the base stations (11, 12) so that the call accept request to the target base station is performed, the success rate of the call accept request while reducing the overhead of exchanging the message related to the resource status information between the base stations To increase.

4 is a flowchart illustrating a method for controlling call admission between base stations according to an embodiment of the present invention.

Referring to FIG. 4, when a terminal accepts a call from a serving base station, the serving base station determines whether there is a surplus resource (Resource Block) (S110).

Then, the serving base station checks whether there is a surplus resource and whether the CNIR value of the terminal exceeds the threshold (S120). In this case, the CNIR value of the terminal is preferably measured through a pilot channel.

As a result of the check, when the surplus resources exist in the serving base station and the CNIR value of the terminal meets the threshold, the serving base station allows the terminal to accept the call (S160). At this time, the resource status information related message exchange with the neighbor base stations is not made.

On the other hand, when there is no surplus resource in the serving base station, or the CNIR value of the terminal is less than or equal to the threshold, the serving base station of the present invention rejects the call acceptance request of the terminal.

In this case, the serving base station requests load information from neighboring base stations. At this time, the load information preferably includes the number of surplus resources and channel information (S130).

The exchange of load information between the base station and another base station may be directly performed by exchanging a load status request message and a resource status response message through an X2 interface.

As described above, the serving base station selects the target base station and performs a call acceptance request based on the information obtained through the exchange of load information between the base stations (S140). The target base station receiving the call acceptance request determines whether the terminal accepts the call in consideration of the number of surplus RBs and channel information.

That is, as in the serving base station, it is determined whether the surplus resources exist in the target base station, and it is determined whether the required condition is satisfied by comparing the CNIR value of the terminal with a CNIR _threshold (S150).

At this time, if the surplus resources exist in the target base station and the CNIR value of the terminal meets the threshold, the serving base station allows the terminal to accept the call (S160).

However, when it is determined that the condition is not satisfied or the connection of the selected target base station is not possible, the step of reselecting the base station of the neighboring cell is additionally performed.

Meanwhile, the present invention as described above may be more usefully applied to 3GPP LTE (3GPP Long Term Evolution) system and LTE-Advanced system promoted by 3GPP, preferably wirelessly between base stations such as eNB (evolved NodeB). It may be more suitable for a communication network / system which performs resource information exchange.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention belongs may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. You will understand that. Therefore, the embodiments described above are to be understood in all respects as illustrative and not restrictive.

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

2 is an explanatory diagram showing an independent call acceptance process in a serving base station according to an embodiment of the present invention.

3 is an explanatory diagram illustrating a call acceptance request process to a neighbor base station according to an embodiment of the present invention.

4 is a flowchart illustrating a call admission control method between base stations according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10, 11, 12: base station

20: terminal

Claims (7)

When a call acceptance request message is received from the terminal, identifying a surplus resource to determine whether a surplus resource exists in the corresponding serving base station; A threshold comparison step of comparing a carrier-to-noise and interference ratio (CNIR) measured by the terminal with a CNIR _threshold ; And If there is excess resources in the serving base station, and the CNIR is greater than the threshold (CNIR _threshold ) includes a call acceptance step of accepting the call of the terminal, And the step of accepting a call is independently performed without exchanging load information between base stations. The method of claim 1, A load information request step of the serving base station requesting load information from neighboring base stations when the call acceptance request of the terminal fails; And And selecting a target base station so as to correspond to load information received from the neighbor base stations and requesting call acceptance of the terminal. The method of claim 2, If there is excess resources in the target base station, and the CNIR value of the terminal is greater than the CNIR _threshold (CNIR _threshold ), the call acceptance control method between the base stations, characterized in that to allow. The method according to claim 2 or 3, The method for controlling call admission between base stations according to claim 1, wherein if the surplus resource does not exist in the target base station, or if the CNIR value of the terminal is less than or equal to a CNIR _threshold , the call acceptance request is rejected. The method of claim 1, If there is no surplus resource in the serving base station, or if the CNIR value is less than or equal to the CNIR _threshold (CNIR _threshold ), the call accept control method between the base station characterized in that the terminal rejects. The method according to claim 1 or 2, And the load information is the number of surplus resources and channel information. 4. The method according to any one of claims 1 to 3, The CNIR value is measured through a pilot channel.

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