KR20130028624A - Method and system for automated assigning of physical cell identity - Google Patents
Method and system for automated assigning of physical cell identity Download PDFInfo
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- KR20130028624A KR20130028624A KR1020120037892A KR20120037892A KR20130028624A KR 20130028624 A KR20130028624 A KR 20130028624A KR 1020120037892 A KR1020120037892 A KR 1020120037892A KR 20120037892 A KR20120037892 A KR 20120037892A KR 20130028624 A KR20130028624 A KR 20130028624A
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- pci
- base station
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- determination method
- ncl
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/18—Network planning tools
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W40/00—Communication routing or communication path finding
- H04W40/24—Connectivity information management, e.g. connectivity discovery or connectivity update
Abstract
Description
The present invention relates to the field of Long Term Evolution (LTE), and more particularly, to a method and system for automatically allocating a physical cell identity (PCI), which is one of the initial setting values of a base station.
As the mobile communication market demands high speed data, coverage of base stations is gradually decreasing. Network operators need more base stations in the same area for high quality data services and are expensive to install and maintain multiple base stations. That is, a large number of people and time are required to determine the wired and wireless parameters. Since it is not easy to find the optimal conditions for the variable location of the base station and the changing wireless environment, the self-organizing network (SON) is needed to automatically install the base station and the network and adapt to the changing wireless and data traffic environments. .
PCI (Physical Cell Identity) is the most basic parameter to configure the base station. The base station performs a random sequence generation, a synchronization signal generation, a subcarrier mapping of a downlink reference signal using a PCI, and the like.
The wireless network operator configures each PCI according to which cells are configured around the base station, and accordingly, configures a neighbor cell list (NCL). According to a conventional method of configuring PCI and NCL, a base station The NCL was configured by manual rather than silent installation. A component of the NCL is composed of PCI used by neighboring cells, and the terminal performing the handover may increase the handover speed by searching the limited PCI by receiving the NCL from a serving cell.
As the mobile communication market demands small cell coverage, more base stations are required to provide quality services in the same area, and cost is required to install and maintain multiple base stations. In this situation, it is difficult to manually set PCI and NCL each time at base station installation. Moreover, in case of small base stations such as femtocells, more base stations are expected to be installed, the base stations should be freely turned on and off, and the mobility of the base stations should be guaranteed. In this case, manually installing PCI and NCL must be a complex process as well as a cost issue. Therefore, there is a need for a method of automatically setting the PCI and NCL of the base station.
The present invention relates to a method and system for automatically allocating a physical cell identity (PCI), which is one of the initial setting values of a base station.
PCI automatic allocation system of the present invention, the information collection unit for collecting information necessary for PCI allocation and neighbor cell list (NCL) configuration; A PCI allocator configured to determine PCI using at least one PCI determination method; And an NCL component configured to set the neighbor cell list in association with the PCI determination method used by the PCI allocator.
In addition, the PCI automatic allocation method of the present invention comprises the steps of: collecting information necessary for PCI allocation and neighbor cell list (NCL) configuration; Determining PCI of the base station using at least one PCI determination method; And setting the neighbor cell list in association with the at least one PCI determination method.
According to the present invention, it is possible to easily perform the installation and maintenance of the base station by automatically setting the physical cell identity (PCI) and neighbor cell list (NCL), which are basic parameters set in the base station, and can be economically performed at low cost. Can be.
1 is a block diagram showing a configuration of a mobile communication system according to an embodiment of the present invention;
2 is an exemplary view showing a PCI collision phenomenon according to an embodiment of the present invention.
3 is an exemplary view showing a PCI confusion phenomenon according to an embodiment of the present invention.
4 is an exemplary view showing an OAM subsystem according to an embodiment of the present invention.
5 is a block diagram showing a configuration of an information collector according to an embodiment of the present invention.
6 is an exemplary view showing a configuration of a network according to an embodiment of the present invention.
7 is an exemplary view showing a configuration for evaluating a micro base station according to an embodiment of the present invention.
8 is an exemplary view showing a PCI collision performance according to an embodiment of the present invention.
9 is an exemplary diagram showing PCI confusion performance 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. In the following description, well-known functions or constructions will not be described in detail if they obscure the subject matter of the present invention.
In a mobile communication system, a plurality of subscriber terminals and a plurality of micro-base stations simultaneously use the same frequency channel. Therefore, since the use of the same frequency channel causes interference between the concurrent talker and the micro-base station, each micro-base station should appropriately control the transmission power in order to improve the system efficiency and the call quality. In the present invention, the small base station may include a femto base station, a pico base station, a micro base station, an indoor base station, and a relay used for cell expansion. In the drawings of the present invention, a macro base station is described as an example of an outdoor base station, and a femto base station is described as an example of a micro base station.
1 is a block diagram illustrating a configuration of a mobile communication system according to an embodiment of the present invention.
As shown in FIG. 1, the mobile communication system includes, for example, a Global System for Mobile communication (GSM), a 2G mobile communication network such as code division multiple access (CDMA), a long term evolution (LTE) network, a wireless Internet such as WiFi, and a WiBro ( Cellular networks such as Wireless Broadband Internet (WiMax) and World Interoperability for Microwave Access (WiMax) or cellular networks that support packet transmission (e.g., 3G cellular networks such as WCDMA or CDMA2000, High Speed Downlink Packet Access (HSDPA) or High Speed (HSUPA) 3.5G mobile communication network such as Uplink Packet Access, or 4G, etc. to be developed in the future) and macro base station (eNB) 30, femto
As shown in FIG. 1, a mobile communication system may be composed of one or more network cells, and different types of network cells may be mixed in the mobile communication system. The mobile communication system includes a femto base station (Home-eNB) 21 to 25 for managing a narrow range of network cells (femtocells), a macro base station (eNB) 30 for managing a wide range of cells (macrocells), and a user terminal. (UE) 10, a Self Organizing & Optimizing Networks (SON)
The
The femto
The femto
The network cell constituting the mobile communication system may include a macro cell and a femtocell. The macrocell may be managed by the
The
The management server (OAM server) 60, which is a network management device of the base station, is responsible for managing configuration information of the
The SON
The MME 50 may include any entity used to manage call processing, etc. of the
In one embodiment, one
In the mobile communication network, a macro cell and a femto cell are assumed to be mixed, but the network cell may be configured only by the macro cell or the femto cell.
In the 3rd generation partnership project (3GPP) long term evolution (LTE), 504 physical cell identity (PCI), which is one of the basic parameters provided by the SON
The
If a base station is installed, whether a base station using OSG or a CSG, the PCI should be set within a predetermined range. In the case of the base station using the OSG, one of 504 PCIs is used, and in the case of the base station using the CSG, one PCI must be satisfied within the range specified by csg-PhysCellIdRange.
1. "collision-free": PCI must be unique within cell coverage.
2. "confusion-free": Peripheral cells must not be assigned the same PCI.
Collision-free means that newly installed base stations and neighboring base stations do not have the same PCI, and confusion-free means that they do not have the same PCI between base stations located near the newly installed base stations. will be.
2 is an exemplary view when a PCI collision occurs according to an embodiment of the present invention, Figure 3 is an exemplary view when a PCI confusion occurs according to an embodiment of the present invention. As shown in FIG. 2, since the same PCI A is allocated to the adjacent base stations, PCI collision occurs. As shown in FIG. 3, since PCI is allocated between the adjacent base stations, there is no PCI collision. PCI confusion occurs because a base station allocated with the same PCI B is located next to both of the centrally located base stations to which is allocated.
When allocating PCI in the range of 504, PCI collision or PCI confusion is less likely.However, if 504 PCI is divided according to the base station operation purpose, the probability of occurrence of PCI collision or PCI confusion increases, and the base station using CSG Selects PCI from a limited range, increasing the likelihood of a PCI conflict or PCI confusion. However, when the PCI range is widened, since the
Rather than relying only on cell planning tools, etc. to increase the installation cost, maintenance cost and performance of the wireless network, the base station itself is operating to predict the wireless environment and automatically set necessary parameters. This method of automatically setting parameters required for the base station is called a self organizing network (SON). The SON is divided into basic setup, initial radio configuration, self-optimization, etc. as follows, and is performed with the help of an operation and maintenance (OAM) subsystem as shown in FIG. do.
1. Preferences
IP address configuration,
-Associate with a gateway
-Authentication
2. Initial Wireless Configuration
Physical Cell ID configuration
Neighbor list configuration
-Establish interfaces (eg, X2)
3. Self Optimization
-Optimize neighbor list
-Coverage and capacity optimization
When the basic setting is completed in the mobile communication system, the initial radio parameters are set before the base station is operated. The most basic of the initial radio parameters is the PCI that the cell will use. A simple method for determining the PCI of the base station is to determine any PCI within the PCI range (504 for the OSG, csg-PhysCellIdRange for the CSG). However, if a random PCI is determined without information about the neighboring cell of the base station, the PCI collision and PCI confusion cannot be effectively controlled. To compensate for this, self optimization is performed during the operation of the base station. In order to perform self-optimization, the base station receives handover information from the connected
5 is an exemplary view showing the configuration of a PCI automatic allocation system according to an embodiment of the present invention.
As shown in FIG. 5, the PCI
The
Even if the base station includes a sniffer, the PCI information that can be known from the physical layer can be detected, but if the CGI information cannot be received by receiving the RRC broadcast message, the location is estimated using the detected PCI information. The CGI information may be obtained or the approximate location may be estimated through an IP address, and the CGI information may be obtained. In order to estimate the CGI after the position estimation using the PCI information, one of the detected PCIs is selected to be highly related. The closer the transmitter and the receiver are located, the higher the reception power. Therefore, the method of determining the degree of relevance may select the largest reception power for the PCI. When one PCI is selected, the next most relevant PCI is determined to calculate the physical distance or network connection distance for each selected PCI. The physical distance represents the distance by the coordinates on the map, and the network connection distance represents the shortest hopping number for reaching from one base station to another base station. A method of calculating the network connection distance will be described later. Calculating the physical distance or network connection distance for a selected PCI can result in multiple combinations because there are several base stations using the same PCI on the network. Two or more PCI information can be used to increase the accuracy of the estimated location. Finally, the CGI information of the neighbor cell is obtained based on the estimated position.
The PCI allocator 120 allocates PCI using at least one of a received power based PCI determination method, a network connection based PCI determination method, and a statistics based PCI determination method according to the information received from the
In order to use the received power-based PCI determination method, the
In
When calculating the path loss instead of the received power, the PCI with the largest path loss is allocated as shown in
In
The PCI allocator 120 allocates the PCI by the statistical-based PCI determination method when the PCI received from the
In order to use a network connection-based PCI determination method, the
In equation (3)
Is the cell from which you want to configure PCI. It shows the shortest network connection distance to the cell with.If the PCI obtained by the network search is smaller than the range of the settable PCI, the PCI is allocated by the statistics-based PCI determination method.
In order to use the statistics-based PCI determination method, the
The
In the reception power based NCL configuration method, the
In the network connection-based NCL configuration method, the NCL consists of a PCI combination of cells whose network connection distance falls below a predetermined threshold. For reference, when the network connection distance is set to a value less than or equal to 1, the NCL may be set similarly to the reception power-based NCL configuration method.
In the location-based NCL configuration method, the
The
The present invention is configured by the
When Cell X is newly installed and automatically sets up PCI and NCL based on the received power, the received power for each cell must be measured and listed by the magnitude of the received power. In this embodiment, since Cell A and Cell H have the same PCI, the value of Cell A with a larger reception power is used. Assuming that the received power is as follows, Cell X has the smallest received power.
Cell A> Cell B> Cell C> Cell E> Cell D> Cell F> Cell G> Cell I
NCL, which is configured based on the received power, consists of
If Cell X is newly installed and automatically sets up PCI and NCL based on the network connection, you must calculate the network connection distance for each cell. As an example, when Cell A, Cell B and Cell C are found, the shortest network connection distance is as follows. Since Cell A and Cell H use the same PCI, Cell A with the minimum network connection distance is used.
Network connection distance 1: Cell A (PCI 0), Cell B (PCI 1), Cell C (PCI 2)
Network connection distance 2: Cell D (PCI 3), Cell E (PCI 4), Cell G (PCI 6)
Network connection distance 3: Cell F (PCI 5)
Network connection distance 4: Cell I (PCI 7)
As mentioned above, PCI No. 7 assigned to Cell I has the largest network connection distance, so PCI of Cell X is assigned to No. 7 and NCL is network It consists of
If Cell X is newly installed and automatically sets up PCI and NCL based on the statistics, you will need to get PCI statistics for that particular area. In one embodiment, if the statistics for the cell A ~ H excluding Cell I is obtained,
In order to know the effects of the present invention, a simulation environment was constructed as follows.
-Femto base station transmit power: 10dBm
-Femto base station installation type: 5 by 5 grid model
Antenna gain: 0 dBi
Noise Density: -174dBm / Hz
Interference Noise Density: -110dBm / RB
Noise figure: 5dB
Macro base station transmit power: 46dBm
Path Loss for Macro Cells: 100dB (Cell site), 140dB (Cell edge)
The femto base station used a 5 by 5 grid model as shown in FIG. 7. The 5 by 5 grid model is an installation model for evaluating femto base stations in 3GPP. There are 5 base stations in 10m intervals and 25 base stations in total. The 25 base stations were simulated in two cases, a cell site located close to the macro cell and a cell edge located far from the macro cell.
8 and 9 illustrate PCI collision performance and PCI confusion performance according to each PCI determination method. The random PCI configuration method is very poor in performance, but there are many improvements that can be made with the statistics-based PCI decision method. The method of determining PCI based on received power and the method of determining PCI based on statistics have different performances depending on the cell site and cell edge.In the case of small interference from the cell, the received power based PCI and network connection based PCI are determined. Although the performance of the method is slightly different, it converges in a similar range, but when the interference from the macro cell is large (Cell site), the PCI that can be received decreases due to the macro interference, which causes a significant performance degradation.
While the above methods have been described through specific embodiments, the methods may also be implemented as computer readable code on a computer readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may be implemented in the form of a carrier wave (for example, transmission over the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the above embodiments can be easily deduced by programmers of the present invention.
Although the present invention has been described in connection with some embodiments thereof, it should be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention as understood by those skilled in the art. something to do. It is also contemplated that such variations and modifications are within the scope of the claims appended hereto.
10:
30: macro base station 40: SON server
50: MME 60: Management Server (OAM Server)
Claims (17)
An information collector configured to collect information necessary for PCI allocation and neighbor cell list (NCL) configuration;
A PCI allocator configured to determine PCI using at least one PCI determination method; And
And an NCL component configured to set the neighbor cell list in association with a PCI determination method used by the PCI allocator.
The PCI automatic allocation system further comprises a PCI determination unit for determining whether the PCI determined by the PCI allocation unit and the PCI collision and PCI confusion of the neighbor cell list set by the NCL configuration unit.
The PCI determining unit,
If the PCI collision and PCI confusion occurs, the PCI and the neighbor cell list is reconfigured, and if the PCI collision and PCI confusion is not resolved even through the reconfiguration of the PCI and the neighbor cell list, the PCI and neighbor cell list of other base stations To reset, PCI auto allocation system.
The information collecting unit,
PCI information set in the neighboring cell of the base station, reception power for each PCI, CGI and neighboring cell list set in the neighboring cell of the base station, and the neighboring information as information necessary for the PCI allocation and the neighbor cell list configuration; PCI automatic allocation system for collecting location information of a base station that governs a cell.
The location information may include:
A method for estimating an approximate location through an IP address, a method for estimating a location through an apparatus for indicating a location, and a base station that manages the neighbor cell by calculating a physical distance or a network connection distance using the PCI information. Estimating using at least one of the methods of estimating the installed location.
The information collecting unit,
And at least one of a sniffer or downlink receiver, a user equipment, an operation and maintenance (OAM) server, and a global positioning system (GPS) installed in the base station.
The PCI determination method,
A PCI automatic allocation system comprising a received power based PCI determination method, a network connection based PCI determination method and a statistics based PCI determination method.
The received power based PCI determination method,
Received signal strength indicator (RSSI), reference signal received power (RSRP), reference signal received quality (RSRQ), synchronization signal received power, or the received power for PCI and the neighboring cell allocated from the information collecting unit The PCI automatic allocation system for receiving the received power information including at least one of the values calculated through the to select the PCI with the lowest received power.
The received power based PCI determination method,
If path attenuation is calculated for each PCI, then the PCI auto-allocation system selects the PCI with the largest path attenuation.
The PCI allocation unit,
If the PCI collected by the information collecting unit is smaller than the range of the settable PCI, PCI except for the collected PCI to determine the PCI using the statistics-based PCI determination method, PCI automatic allocation system.
The network connection based PCI determination method,
And a PCI, CGI and neighbor cell list allocated to the neighboring cell from the information collecting unit to calculate a network connection distance to select a PCI having the longest network connection distance.
The network connection distance is,
PCI automatic allocation system that represents the shortest hopping number for reaching from one base station to another.
The PCI allocation unit,
The PCI automatic allocation system in the statistics-based PCI determination method to determine the PCI having the minimum number of times by receiving the position information from the information collecting unit by measuring the number of times of PCI use.
Collecting information necessary for PCI allocation and neighbor cell list (NCL) configuration;
Determining PCI of the base station using at least one PCI determination method; And
And setting the neighbor cell list in association with the at least one PCI determination method.
And determining whether the determined PCI and the PCI neighbor and PCI confusion of the set neighbor cell list are determined.
Determining whether the PCI conflict and PCI confusion,
Reconfigure the PCI and the neighbor cell list when the PCI collision and PCI confusion occurs, and if the PCI collision and the PCI confusion are not resolved by the reconfiguration of the PCI and the neighbor cell list PCI reassignment method.
The PCI determination method,
PCI automatic allocation method, including a received power based PCI determination method, a network connection based PCI determination method and a statistics based PCI determination method.
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101520810B1 (en) * | 2013-09-04 | 2015-05-22 | 주식회사 엘지유플러스 | System And Method For Physical Cell Identification Confusion And Collision Detecting |
CN105323853A (en) * | 2014-07-30 | 2016-02-10 | 普天信息技术有限公司 | Service cell index value allocation method in dual-connection network |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
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KR101520810B1 (en) * | 2013-09-04 | 2015-05-22 | 주식회사 엘지유플러스 | System And Method For Physical Cell Identification Confusion And Collision Detecting |
CN105323853A (en) * | 2014-07-30 | 2016-02-10 | 普天信息技术有限公司 | Service cell index value allocation method in dual-connection network |
CN105323853B (en) * | 2014-07-30 | 2019-02-05 | 普天信息技术有限公司 | The distribution method of serving cell index value in a kind of dual link network |
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