KR20120059723A - Method and apparatus for assigning cell id in mobile communication system - Google Patents

Abstract

PURPOSE: A cell identity allocation method in a mobile communication system is provided to selectively utilize a centralized method or a distribution method by grasping location information around eNB(evolved-NodeB). CONSTITUTION: In case newly installed eNB is unable to utilize geographic information, a PCI server determines the usage of a distribution method(100,105). The PCI server grasps numbers of the eNB which are located within two hop distance or three hop distance(110). In case the numbers of the eNB is smaller than threshold values, the PCI server determines the usage of the distribution method(115). In case the numbers of the eNB is over the threshold value, the PCI server determines the usage of a centralized method(120).

Description

METHOD AND APPARATUS FOR ASSIGNING CELL ID IN MOBILE COMMUNICATION SYSTEM}

The present invention relates to cell ID allocation, and more particularly, to a method and apparatus for allocating a physical cell ID (PCI) in a 3rd generation partnership project long term evolution (3GPP LTE) system.

As a delimiter for identifying an eNB (evolved Node B) which is a base station, a terminal may include a physical cell ID (PCI). However, these PCIs are limited to 504. There are two types of PCI allocation schemes: the static scheme by the operator and the automatic allocation scheme by the self-organizing network (SON).

Recently, SON techniques have emerged as a policy to reduce OPEX (Operation Expenditure). There are two types of auto-allocation schemes by SON, which are centralized by the PCI server and distributed by the eNB.

In order to use the centralized technique, when the eNB knows its latitude and longitude information in advance, calculates the distance using the latitude and longitude information, and transmits the distance to the PCI server, the PCI server satisfies the PCI value that satisfies the allocation condition. Assign.

In addition, the distributed scheme can be used when small nodes such as pico and femto eNBs are installed indoors and do not know the location information. When a PCI list is allocated from a PCI server, the eNB may access the PCI information of neighboring nodes for a certain time. It is a technique that collects and manages the collected PCI information as a black list and excludes it from allocation.

 ENBs installed in 3GPP LTE communication systems include various types such as Macro, Pico, and Femto. The eNB is divided into a node capable of knowing location information through a GPS receiver and a node having no GPS receiver or no location information.

In such a case, using only the centralized technique or the distributed technique has an inefficient problem per PCI hill.

An object of the present invention is to provide a method and apparatus for cell ID allocation in a mobile communication system.

Another object of the present invention is one of a centralized technique or a distributed technique in determining a PCI according to the distribution of an eNB newly installed in a mobile communication system, an eNB having location information of neighboring neighbor nodes, and an eNB having no location information. To provide a method and apparatus for using.

According to a first aspect for achieving the objects of the present invention, when a newly installed base station knows its position in a PCI allocation method of a physical cell ID (PCI) server in a mobile communication system, a predetermined distance from the base station The process of determining the number of base stations that know its own location and the number of base stations whose own location is above the threshold, among all the base stations located within the threshold, the process of determining the use of the centralized technique and the newly installed base station If it is not known the location of the, characterized in that it comprises a process of determining the use of the distribution technique.

According to a second aspect for achieving the objects of the present invention, in the distributed PCI allocation method of the base station in the mobile communication system, the process of starting timer 1, and until the timer 1 expires, PCI of the base station located in the vicinity Acquiring the PCI, excluding PCI acquired during the timer 1 from the plurality of PCIs allocated from the PCI server, starting the timer 2, and excluding the remaining PCI from within the predetermined position and a predetermined distance And removing the PCI of the base station until the timer 2 expires, and setting one of the remaining PCIs as its own PCI.

According to a third aspect for achieving the objects of the present invention, in a device of a PCI server for allocating PCI in a mobile communication system, a backhaul communication unit for communicating with another node, and the newly installed base station knows its location In this case, among all the base stations located within a predetermined distance from the base station, the number of base stations that know their location is determined, and when the number of base stations that know their location is greater than or equal to the threshold, the use of the centralized technique is determined, If the newly installed base station does not know its location, it characterized in that it comprises a control unit for determining the use of the distribution scheme.

According to a fourth aspect for achieving the objects of the present invention, an apparatus of a base station for allocating PCI using a distributed scheme in a mobile communication system, comprising: a backhaul communication unit communicating with another node, starting timer 1, and starting the timer Until 1 expires, acquires PCI of the base station located nearby, excludes the PCI acquired during the timer 1 from a plurality of PCIs allocated from the PCI server, starts timer 2, and among the remaining PCIs, It is characterized in that it comprises a control unit for excluding the PCI of the base station located within a predetermined distance of the position of until again until the timer 2 expires, and to set one of the remaining PCI to its own PCI.

The present invention uses a centralized technique when a lot of eVBs that know the location information are distributed around the newly installed eNB efficiently by using a hybrid scheme of dynamically allocating PCI according to the surrounding situation in the LTE network. If there are a lot of eNBs that do not know the information, there is an advantage that can be used in a distributed technique.

1 is a diagram illustrating an operation technique of a PCI server according to an exemplary embodiment of the present invention.
2 is a flowchart illustrating an operation process of an eNB according to an embodiment of the present invention.
3 is a block diagram of a PCI server and an eNB according to an embodiment of the present invention.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

Hereinafter, the present invention will be described a method and apparatus for cell ID allocation in a mobile communication system.

In the present invention, when a new eNB is installed, a hybrid technique such as Higi is used in the process of allocating PCI. When the PCI allocation scheme is determined as the distributed scheme in the hybrid scheme, the distributed scheme in the present invention is used.

If the newly installed eNB knows its own location information, it finds the number of nodes that know the location information within the 3xR range. If the number of nodes knowing the location information is smaller than the threshold value, the PCI allocation scheme is determined by a distributed scheme, and when the number of nodes knowing the location information is larger than the threshold, the PCI allocation scheme is determined by a centralized scheme.

The dispersion technique of the present invention is as follows.

When the use of the distributed technique is determined, the installed eNB is a triad that estimates its location information using the location information of three nodes when there are three or more nodes that know the location information among neighbor node information collected for a certain time. Calculate your position using the survey method.

Then, the installed eNB blacklists the PCIs of the nodes in the 3R and the neighboring nodes collected for a certain time through the calculated location information, and the smallest value among the PCIs excluding the blacklist from the initial allocated PCI list. Allocate PCI. Here, a node represents an eNB, and R represents a distance from its location to the nearest eNB.

1 is a diagram illustrating an operation process of a PCI server according to an exemplary embodiment of the present invention.

Referring to FIG. 1, when a newly installed eNB is not able to utilize its terrain information (step 100), that is, when it does not know its location information, the PCI server determines to use a distribution technique ( 105 steps)

If the newly installed eNB can utilize its terrain information (step 100), that is, if it knows its location information, the PCI server is located in all eNBs located within 2 hop distance or 3R distance of the eNB. In this regard, the number of eNBs that know its own location is determined.

If the number of eNBs that know its location is smaller than the threshold (step 110), the PCI server determines to use the distribution technique (step 115).

If the number of eNBs that know its location is greater than or equal to a threshold value, the PCI server determines to use the centralized technique (step 120).

Here, the PCI server provides one PCI to a newly installed eNB when using a centralized scheme, and provides a plurality of PCI when using a distributed scheme. 2, which will be described below, illustrates an example in which a dispersion technique is used.

2 is a flowchart illustrating an operation process of an eNB according to an embodiment of the present invention.

Referring to FIG. 2, the eNB receives a plurality of PCIs from a PCI server.

Thereafter, the eNB determines one PCI to use temporarily among the plurality of PCIs and starts timer 1 (step 205).

Thereafter, until the timer 1 expires (step 240), when PCI acquisition is possible from the eNB located in the vicinity (step 210), the eNB acquires the peripheral PCI (step 215) and exchanges PCI with the eNB located in the vicinity. If this is possible (step 225), it is obtained by exchanging PCI with eNBs located nearby (step 230).

In this case, the eNB excludes the PCI acquired from a plurality of PCI allocated from the PCI server (step 220, 235).

Thereafter, the eNB starts timer 2 (step 242). Thereafter, the eNB excludes until the timer 2 expires (step 260), and among the remaining PCI, the number of PCIs that know its location information is 3 or more (where 3 is an example and may be changed). In operation 245, the location of the eNB is calculated using trilateration (step 250).

Thereafter, the eNB excludes the PCI of the eNB located within 3R again from the remaining PCI (step 255).

Thereafter, the eNB selects the PCI having the smallest value among the remaining PCIs without being excluded from the PCIs provided from the PCI server (step 265). The selected PCI is set as the PCI of the eNB (step 270).

3 is a block diagram of a PCI server and an eNB according to an embodiment of the present invention.

Referring to FIG. 3, the eNB includes a radio frequency (RF) processor 310, a modem 320, a backhaul communication unit 330, a storage unit 340, and a controller 350. The controller 350 includes a PCI manager 355.

The PCI server includes a backhaul communication unit 330, a storage unit 340, and a control unit 350. The controller 350 includes a PCI manager 355.

First, the eNB will be described below.

The RF processor 310 performs a function for transmitting and receiving a signal through a wireless channel such as band conversion and amplification of the signal. That is, the RF processor 310 up-converts the baseband signal provided from the modem 320 to an RF band signal, transmits the signal through an antenna, and downwards the RF band signal received through the antenna to the baseband signal. Convert.

The modem 320 performs a baseband signal and bit string conversion function according to the physical layer standard of the system. For example, during data transmission, the modem 320 generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and then performs an Inverse Fast Fourier Transform (IFFT) operation and CP ( Cyclic Prefix) is used to configure OFDM symbols. In addition, upon receiving data, the modem 320 divides the baseband signal provided from the RF processor 310 in OFDM symbol units and restores signals mapped to subcarriers through a fast fourier transform (FFT) operation. After that, the received bit stream is recovered by demodulation and decoding.

The backhaul communication unit 330 provides an interface for communicating with another node (for example, a PCI server or another eNB).

The storage unit 340 stores data such as a basic program, an application program, and user content for the operation of the eNB. The storage unit 340 provides stored data at the request of the control unit 350. In particular, the storage unit 340 stores the PCI of itself and other eNBs.

The controller 350 controls the overall operations of the eNB. For example, the controller 350 configures downlink data and provides the downlink data to the modem 320 and interprets the uplink data provided from the modem 320.

The PCI management unit 355 receives a plurality of PCI from the PCI server.

Thereafter, the PCI manager 355 determines one PCI to be temporarily used among the plurality of PCIs and starts timer 1. Thereafter, the PCI manager 355 acquires the PCI when the PCI can be acquired from the eNB located in the vicinity until the timer 1 expires, and when the PCI exchange is possible with the eNB located in the neighbor, the eNBd located in the vicinity The PCI management unit 355 excludes PCI obtained from a plurality of PCIs allocated from the PCI server.

Thereafter, the PCI manager 355 starts timer 2 and excludes until timer 2 expires, and among the remaining PCIs, the number of PCIs of eNBs that know their own location information is 3 or more (where 3 is an example). And the position of the eNB using trilateration.

Thereafter, the PCI manager 355 excludes the PCI of the eNB located within 3R again from its position among the remaining PCI. Thereafter, the PCI manager 355 selects the PCI having the smallest value among the remaining PCIs, not excluded from the PCIs provided from the PCI server, and sets the PCI as its own PCI.

The PCI server will now be described.

The backhaul communication unit 330 provides an interface for communicating with another node (eg, eNB).

The storage unit 340 stores data such as a basic program, an application program, and user content for the operation of the PCI server. The storage unit 340 provides stored data at the request of the control unit 350. In particular, the storage unit 340 stores the PCI of the eNB.

The controller 350 controls overall operations of the PCI server.

When the newly installed eNB is not able to use its own terrain information, that is, it does not know its location information, the PCI server determines the use of the distribution scheme.

If the newly installed eNB can utilize its terrain information, that is, if it knows its own location information, the PCI management unit 355 to all eNBs located within 2 hop distance or 3R distance to the eNB. In this regard, the number of eNBs that know its own location is determined.

If the number of eNBs that know its location is smaller than a threshold value, the PCI manager 355 determines to use a distributed technique.

If the number of eNBs that know the location of the voluntary position is greater than or equal to a threshold value, the PCI manager 355 determines to use the centralized scheme.

Here, the PCI management unit 355 provides a single PCI to the eNB is newly installed when using the centralized scheme, and provides a plurality of PCI when using distributed distribution.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

Claims (22)

In the PCI allocation method of a physical cell ID (PCI) server in a mobile communication system,
When the newly installed base station knows its own location, determining a number of base stations that know its own location among all the base stations located within a predetermined distance from the base station,
If the number of base stations that know their location is above the threshold, the process of determining the use of the centralized technique,
If the newly installed base station does not know its location, characterized in that it comprises the step of determining the use of the distribution scheme,
The method of claim 1,
If the number of base stations that know its location is less than the threshold, further comprising determining to use a distributed technique.
The method of claim 1,
The predetermined distance is
2 hop distance or 3R distance.
The method of claim 1,
If the centralized scheme is determined, further comprising transmitting one PCI to a newly installed base station.
The method of claim 1,
If the distribution scheme is determined, further comprising the step of transmitting a plurality of PCI to the newly installed base station.
In the distributed PCI allocation method of the base station in the mobile communication system,
Starting timer 1,
Acquiring PCI of a base station located nearby until timer 1 expires;
Excluding the PCI acquired during the timer 1 from the plurality of PCIs allocated from the PCI server;
Starting timer 2,
Among the remaining PCI, excluding the PCI of the base station located within a predetermined distance from its own location until the timer 2 expires, and
The method comprising the step of setting one of the remaining PCI out of the PCI as its own PCI.
The method according to claim 6,
Before starting Timer 1,
Receiving a plurality of PCI from the PCI server,
The method of claim 1 further comprising the step of determining one of the plurality of PCI to use temporarily.
The method according to claim 6,
Until the timer 1 expires, the process of acquiring the PCI of the base station located nearby,
Acquiring the PCI when the PCI can be acquired from the neighboring base stations until the timer 1 expires;
And exchanging PCI when PCI is exchanged with a base station located nearby.
The method according to claim 6,
Among the remaining PCI, the process of excluding the PCI of the base station located within a predetermined distance from its own location until the timer 2 expires,
Calculating the position of the base station by using a triangulation method when the number of PCIs of the base station that knows its position information is greater than or equal to the number of PCIs left after the timer 2 expires;
And re-excluding the PCI of the base station located within a predetermined distance from the calculated position.
The method of claim 9,
The predetermined distance is
3R distance.
The method according to claim 6,
The process of setting one PCI out of the remaining PCI as its own PCI,
And setting the PCI having the smallest value among the remaining PCIs as its own PCI.
In a device of a PCI server for allocating PCI in a mobile communication system,
A backhaul communication unit for communicating with another node,
When a newly installed base station knows its own location, of all the base stations located within a predetermined distance from the base station, the number of base stations that know its own location is determined, and the number of base stations that know its own location is a threshold value. In case of the above, the apparatus comprises a control unit for determining the use of the centralized technique, and for determining the use of the distributed technique when the newly installed base station does not know its location.
13. The method of claim 12,
The control unit,
And if the number of base stations that know its location is less than the threshold, determine to use a distributed technique.
13. The method of claim 12,
The predetermined distance is
Apparatus characterized in that the distance is two hops or 3R distance.
13. The method of claim 12,
The control unit,
And when the centralized scheme is determined, transmitting one PCI to the newly installed base station through the backhaul communication unit.
13. The method of claim 12,
The control unit,
And when the distribution scheme is determined, transmitting a plurality of PCIs to the newly installed base station through the backhaul communication unit.
In the base station apparatus for allocating PCI using a distributed scheme in a mobile communication system,
A backhaul communication unit communicating with other nodes,
Start timer 1, and until the timer 1 expires, acquire the PCI of the base station located nearby, exclude the PCI acquired during the timer 1 from a plurality of PCI allocated from the PCI server, start timer 2 And a control unit for excluding the PCI of the base station located within a predetermined distance from the excluded PCI, until the timer 2 expires, and setting one of the remaining PCI to the own PCI. Device characterized in that.
The method of claim 17,
The control unit,
Before starting Timer 1,
Receive multiple PCI from PCI server,
And determining one of the plurality of PCIs to be temporarily used.
The method of claim 17,
The control unit,
When acquiring the PCI of the base station located in the vicinity until the timer 1 expires,
Until the timer 1 expires, if the PCI can be obtained from the base stations located nearby, obtain a POI, and C
Device for exchanging PCI when the PCI exchange with the base station located nearby.
The method of claim 17,
The control unit,
Among the remaining PCI excluded, if the PCI of the base station located within a predetermined distance from its location is excluded again until the timer 2 expires,
If the number of PCIs of the base station that knows its location information is greater than or equal to the number of PCIs remaining after the timer 2 expires until the timer 2 expires, its location is calculated using trilateration,
And re-exclude PCI of the base station located within a predetermined distance from the calculated position.
The method of claim 20,
The predetermined distance is
Apparatus characterized in that the 3R distance.
The method of claim 17,
The control unit,
If you exclude one of the remaining PCIs and set it as your own PCI,
A device which sets a PCI having the smallest value among the remaining PCIs as its own PCI.

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