KR20100034209A - Method for beginning search of femto ap in mobile internet terminal - Google Patents

Abstract

PURPOSE: A method for starting to search an indoor base station in a mobile internet terminal is provided to start searching an indoor base station around the indoor base station whose access is permitted according to receiving signal strength from an adjacent outdoor base station. CONSTITUTION: RSSI(Received Signal Strength Indication) profile information from an adjacent outdoor base station measured in an indoor base station whose access is permitted is saved(1001). Partial similarity is calculated for the adjacent outdoor base station(1002,1003). An effective outdoor base station is extracted. Total similarity is calculated about the effective outdoor base station(1004,1006~1008). Searching an outdoor base station is started(1010).

Description

METHODO FOR BEGINNING SEARCH OF Femto AP IN MOBILE INTERNET TERMINAL}

The present invention relates to a method for initiating indoor base station search in a portable internet terminal, and more particularly, in a portable internet environment including an indoor base station installed separately, the portable internet terminal is used to receive received signal strength from surrounding outdoor base stations. Accordingly, the present invention relates to an indoor base station search initiation method in a portable Internet terminal for preventing unnecessary waste of power and waste of resources by initiating an indoor base station search near an indoor base station to which access is permitted.

The portable Internet system enables a user to obtain or utilize various information and contents by accessing the Internet at a high speed transmission speed anytime, anywhere using a portable wireless terminal. Therefore, like many cellular communication systems, the portable Internet system supports handover to ensure mobility to mobile terminals.

The portable Internet system is configured such that a cellular mobile communication system having a nationwide wide area and high speed mobility and a wireless LAN system supporting high speed transmission speeds indoors have a complementary relationship. In such a mobile Internet system, various kinds of base stations are located at the same time. These various types of base stations can be broadly divided into indoor base stations and outdoor base stations. These base stations are divided into cell coverage perspectives, main installation sites, and usage aspects.

In general, the handover is a communication path (base station ↔ terminal) to maintain communication when the mobile terminal enters a cell area of another base station (target base station) out of the cell area of the base station (serving base station) with which it is currently communicating. Communication path) refers to changing a target base station located in a moving direction of a terminal.

1 is an exemplary diagram illustrating a handover scenario in a general cellular system.

As shown in FIG. 1, in the cellular system, handover occurs when the MS moves to another cell (101). In such a cellular network, only handover exists between a serving base station and a target base station.

That is, while the terminal moves from cell 1 110 to cell 2 120, the base station providing the service to the terminal MS is changed from BS1 to BS2 (102). In such a cellular system, there is only a single handover scenario from a base station currently being served to a new base station in a moving cell.

FIG. 2 is a diagram illustrating a handover scenario in a portable Internet system composed of a general indoor / outdoor base station.

As shown in FIG. 1, in a portable Internet system composed of indoor / outdoor base stations, not only handover 201 between outdoor base stations, but also indoor-to-outdoor handovers 211, 221, and 231, indoor ↔ There is a handover 241 between indoor base stations.

In this case, the indoor base station in the portable Internet system may operate as a single base station, but a plurality of indoor base stations may be gathered in a building or an area to form one indoor base station group 251.

3 to 6, a description will be given of indoor base station search schemes in a portable Internet system composed of a conventional indoor / outdoor base station.

The indoor base station search method in the conventional portable Internet system composed of indoor / outdoor base station is a manual-based search method (manual search) that initiates the search of the indoor base station through a user's direct command, the terminal continuously indoors Continuous background search for searching for a base station, TA-based search method for initiating a search when a terminal enters a TA (= Tracking Area), GPS (Global Positioning System) for location recognition and indoor base station GPS-based search method for performing a search, and relationship-based search method with a neighboring cell to determine the location of the indoor base station by using the cell ID information of the outdoor base stations around the indoor base station as a fingerprint (Fingerprint).

First, the manual-based search method for initiating the search of the indoor base station through a user's direct command, as shown in Figure 3, by the subscriber direct commands to the terminal in the area where the indoor base station service is permitted, Search for the presence of a content base station. That is, the indoor base station can be searched only by the direct intervention of the subscriber.

This manual-based search method has a disadvantage in that, when the number of indoor base stations increases, the number of direct commands performed by the subscriber increases proportionally in every case, thereby preventing the normal service from being provided.

Next, the continuous search method in which the terminal continuously searches for an indoor base station is a method in which the terminal periodically searches for the presence or absence of indoor base stations located nearby while performing basic processing related to communication.

This continuous search method tends to consume power of a limited terminal in proportion to the search time as the search of the indoor base station is performed.

Next, the TA-based search method for starting a search when entering a TA (= Tracking Area), as shown in FIG. 4, reports and registers that the UE is in the TA to the network, and registers the TA as the UE moves. Search for indoor base stations. In this case, the TA means an area composed of a plurality of adjacent cell sets.

The TA-based discovery method searches for an indoor base station by entering a tracking area (TA) indicating a point where a terminal mainly moves, and a single TA is searched as a set connecting several adjacent macro cells. The disadvantage is that the scope to do so is widened.

Next, a GPS-based search method that recognizes a location by using GPS (= Global Positioning System) and performs an indoor base station search, as shown in FIG. 5, processes a signal of a GPS satellite on the earth to locate a terminal. And obtain the speed information to initiate the search of the indoor base station near the coordinate where the indoor base station is installed.

Such a GPS-based search method has to have a separate GPS chip, induces considerable power consumption, and when used in a building, GPS signal reception is impossible and thus location information is difficult to grasp.

Next, the relationship-based search method with the neighboring cell which locates the indoor base station by using the cell ID information of the outdoor base stations around the indoor base station as a fingerprint, is shown in FIG. 6. Based on the detailed information of the surrounding outdoor cell that can be received by the content base station, the mobile terminal compares this reference information with the current reception information and starts searching for the indoor base station from the point having similar results. At this time, when a change occurs in the outdoor base station that can be received by the indoor base station, the network notifies the terminal as a change-related message.

The relationship-based search method with neighboring cells has been discussed as the most effective method so far. However, when a change occurs in the outdoor cell that is used as a reference, it is negative to the logic for identifying the position due to the relationship between the cells. There is a problem affecting.

It is a problem of the present invention to solve the problems of the prior art as described above.

Accordingly, the present invention provides a mobile Internet environment in which a mobile Internet terminal initiates a search for an indoor base station near an indoor base station to which the portable Internet terminal is allowed access according to the received signal strength from the surrounding outdoor base station. An object of the present invention is to provide an indoor base station search initiation method in a portable Internet terminal for preventing unnecessary waste of power and waste of resources.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

A method of the present invention for achieving the above object, in the method for initiating the search of the indoor base station in the portable Internet terminal, storing the received signal strength profile information from the neighboring outdoor base station measured in the indoor base station is granted access Doing; Extracting a valid outdoor base station by calculating a partial similarity to the surrounding outdoor base station; And calculating a comprehensive similarity for the valid outdoor base station and initiating a search for the indoor base station.

In addition, according to the present invention, the terminals of the portable Internet system can access the indoor / outdoor base stations having different characteristics and receive services through a base station suitable for a subscriber's unique environment such as mobility of the terminal.

In addition, the present invention compares the outdoor base station ID received from the indoor base station and the received signal strength based on a combination of four classes, the outdoor base station ID received while moving the mobile Internet terminal and the received signal strength samples of similarity By starting the search for the target indoor base station from the point exceeding the reference value, it is possible to reduce the number of unnecessary search for the adjacent indoor base station to reduce the time and resources of the indoor base station search process.

In addition, the present invention minimizes the additional overhead by utilizing the conventional procedure performed by the portable Internet terminal in an outdoor base station for indoor base station search.

In addition, the present invention is a problem that causes the increase of power consumption and waste of resources caused by the continuous search to find the indoor base station licensed in the portable Internet environment including the indoor base station installed separately. Initiating a search around a licensed indoor base station allows for efficient handover procedures and increased performance of the portable Internet system.

In addition, the present invention is used for handover of a portable Internet system (hereinafter referred to as a portable Internet system) terminal composed of an indoor / outdoor base station.

In addition, the present invention initiates the search of the indoor base station only near the authorized indoor base station while the portable Internet terminal moves, thereby minimizing the resources required in this process, thereby improving system performance efficiently.

In addition, the present invention utilizes a conventional macro cell signal reception process performed by a mobile Internet terminal in a macro cell, thereby reducing additional overhead performed when searching for an indoor base station.

The present invention as described above, in the portable Internet environment including the indoor base station installed separately, the mobile base station searches for the indoor base station near the indoor base station is permitted access according to the received signal strength from the surrounding outdoor base station By starting, it is possible to prevent unnecessary waste of power and waste of resources.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It can be easily carried out. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, the outdoor base station means a base station having a large communication area located in the center of one cell, and the indoor base station includes a home indoor base station used at home as a base station separately installed by selection.

7 is an exemplary view illustrating an arrangement of indoor / outdoor base stations in a portable Internet system to which the present invention is applied.

As illustrated in FIG. 7, outdoor base stations are disposed at the center of a cell in a portable Internet system to which the present invention is applied, and indoor base stations are independently disposed in a cell area provided by an outdoor base station.

FIG. 8 is a diagram illustrating a handover in a portable Internet system to which the present invention is applied, and illustrates a handover to an indoor base station when a terminal receives a service while moving from an outdoor cell to an indoor cell.

As shown in Fig. 8, in order for a handover to occur, an attempt to find a serviceable indoor base station must be preceded first (801), and after the completion of the indoor base station search is completed, a substantial handover to the target indoor base station is performed. 802. Therefore, the portable Internet system allocates a considerable amount of time and resources to the search for indoor base stations.

Accordingly, the present invention uses received signal strength indication (RSSI) profile information (hereinafter referred to as 'received signal strength profile information') from neighboring outdoor base stations measured by each indoor base station to which access is permitted. In this paper, we propose a method for initiating an indoor base station search near an indoor base station.

In addition, in the present invention, the outdoor base station is referred to as "Macro BS (Base Station)" and the indoor base station as "Femto AP (Access Point)".

Hereinafter, in the portable Internet system composed of indoor / outdoor base stations with reference to FIGS. 9 to 11, the portable Internet terminal initiates a search for the indoor base station using the received signal strength profile information, but not at any position. A process of initiating a search for an indoor base station near the indoor base station will be described in detail.

FIG. 9 is an exemplary view of received signal strength profile information used for initiating an indoor base station search in a portable Internet terminal according to the present invention, and is received from neighboring outdoor base stations measured at each indoor base station to which access is granted. The process of classifying signal strength is shown.

As shown in FIG. 9, received signal strengths from neighboring outdoor base stations in any indoor base station are divided into four classes.

That is, if the received signal strength is in the range (RSSI ≥ R _inner ) that can be received in the 'Inner Cell Area' in the 'Active Serving' cell, the outdoor base station is classified as Class 1, and the received signal strength is defined as' If it is in the range that can be received in outer cell area '(R _outer ≤ RSSI <R _inner ), the outdoor base station is classified as Class 2, and the received signal strength is not an' Active Serving 'cell, but the serviceable range (R _service ≤ RSSI < If it is in R _outer , the outdoor base station is classified as Class 3, and if the received signal strength is within a range where only pilot signals can be received (R _pilot ≤ RSSI <R _service ), the outdoor base station is classified as Class 4 Classify each.

At this time, the size of the class classification boundary value (R _inner , R _outer , R _service , R _pilot ) is R _inner > R _outer > R _service > R _pilot In order.

In addition, the 'Active Serving' cell area is close to the 'Macro BS', so it is far from the 'Inner Cell' and the 'Macro BS', which has a high signal strength and little interference from surrounding signals. It is divided into 'Outer Cell' area with much interference.

As a result, indoor base stations are located at different places, and the outdoor base stations that can communicate at each location and the received signal strengths from the outdoor base stations are different from each other. Therefore, the indoor base stations are used as location information of indoor base stations. That is, the location of the indoor base station can be determined by the combination of the ID of the surrounding indoor base station and the received signal strength from the surrounding outdoor base stations.

FIG. 10 is a flowchart illustrating a method for initiating an indoor base station search in a portable Internet terminal according to the present invention. The received signal strength (RSSI) profile from neighboring outdoor base stations measured at each indoor base station to which access is granted. The process of initiating an indoor base station search near the indoor base station using the information is described.

First, when the portable Internet terminal is powered on (activated), it receives and receives received signal strength (RSSI) profile information from neighboring outdoor base stations measured at each indoor base station through which access is allowed through an outdoor base station (Core network). (1001).

Here, the received signal strength profile information from the neighboring outdoor base stations measured at each indoor base station to which access is allowed includes information on outdoor base stations that can be communicated at each indoor base station, received signal strength (RSSI) from the outdoor base station, and The classification information of the outdoor base station according to the received signal strength, and the classification reference information. In this case, the indoor base station may further include frequency information used by the indoor base station. On the other hand, the classification criteria information means R _inner , R _outer , R _service , R _pilot , and the same applies to all accessible indoor base stations.

Thereafter, the portable Internet terminal sets the class of the outdoor base station according to the received signal strength from the surrounding outdoor base station and records the result in the table (1002). At this time, the portable Internet terminal sets the corresponding class to the received signal strength from any outdoor base station and records it in a table.

Thereafter, at least one partial similarity is calculated by comparing the received signal strength profile information from the neighboring outdoor base stations measured by each indoor base station stored with the grade of the recorded outdoor base station (1003).

That is, for example, if all indoor base stations accessible by the portable Internet terminal are A, B, or C, the received signal strength profile information from the surrounding outdoor base station in the indoor A base station is compared with the grade of the recorded outdoor base station. Calculate A similarity, calculate B similarity by comparing received signal strength profile information from nearby outdoor base station in B indoor base station and the grade of the recorded outdoor base station, and receive signal strength from nearby outdoor base station in C indoor base station C similarity is calculated by comparing the profile information with the grade of the recorded outdoor base station.

Thereafter, it is checked whether there is a partial similarity exceeding a threshold among the calculated partial similarities (1004).

As a result of the comparison (1004), if there is no partial similarity exceeding the threshold, the indoor base station information recorded in the table is deleted (1005), and then the process proceeds to the “1002” process. This is to reduce unnecessary computation for those that are not candidates for searching initiation.

As a result of the comparison (1004), if there is a partial similarity exceeding a threshold value, the rating of the corresponding outdoor base station recorded in the table is maintained (1006).

Thereafter, the process “1002” to “1006” is performed on all surrounding outdoor base stations (1007).

Through this process, the partial similarity calculation process is completed. The partial similarity calculation process is a process for excluding unnecessary outdoor base stations from the comprehensive similarity calculation process to be performed later. The partial similarity calculation process can increase the accuracy and shorten the time required for calculating the similarity. Of course, a comprehensive similarity calculation process may be performed immediately without the partial similarity calculation process.

Thereafter, at least one comprehensive similarity is calculated by comparing the grades of the outdoor base stations recorded in the table with the received signal strength profile information from neighboring outdoor base stations in each of the indoor base stations stored in the table (1008).

Thereafter, it is checked whether there is a comprehensive similarity exceeding a reference value among the calculated similarities (1009).

As a result of the confirmation (1009), if there is no overall similarity exceeding the reference value, the process proceeds to the “1002” process. If there is a comprehensive similarity exceeding the reference value, it is determined that there is an indoor base station in the vicinity. Start 1010.

11 is a diagram illustrating an embodiment of an indoor base station discovery start method in a portable Internet terminal according to the present invention.

As shown in FIG. 11, the first indoor base station 1101 is located in (a) an 'Outer Cell' of an outdoor base station, and (b) only a pilot signal of an outdoor base station and (d) an outdoor base station can be received. c) It is not a 'Serving Cell' of an outdoor base station, but it is in a range that can be serviced.

Accordingly, the class of the surrounding outdoor base station for the indoor base station 1101 on the reference table # 1 is (a) the class of the outdoor base station is Class 2, (c) the class of the outdoor base station is Class 3, It can be seen that the class of (b) outdoor base station and (d) outdoor base station is Class 4.

In addition, the second indoor base station 1102 is located in the (e) 'Outer Cell' of the outdoor base station, and can receive only pilot signals of (a) outdoor base station, (b) outdoor base station and (c) outdoor base station, ( d) Although it is not a 'serving cell' of an outdoor base station, the service is in a range.

Accordingly, the class of the surrounding outdoor base station for the indoor base station 1102 on the reference table # 2 is (e) the class of the outdoor base station is Class 2, (d) the class of the outdoor base station is Class 3, It can be seen that the grades of (a) the base station for outdoor use, (b) the base station for outdoor use, and (c) the base station for outdoor use are Class 4.

In addition, the third indoor base station 1103 is located in (b) the 'Outer Cell' of the outdoor base station, (d) can receive only pilot signals of the outdoor base station, (a) the outdoor base station and (c) the outdoor base station ' It's not a Serving Cell, but it's within the scope of service.

Accordingly, the class of the surrounding outdoor base station for the indoor base station 1103 on the reference table # 3 is (b) the class of the outdoor base station is Class 2, and (a) the outdoor base station and (c) the outdoor base station. It can be seen that the class is Class 3, and (d) the class of the outdoor base station is Class 4.

In the above embodiment, the indoor base station search initiation method will be described in detail.

First, as a result of extracting a valid outdoor base station through the partial similarity calculation process at the corresponding position at time t = 0, as can be seen from the field "Macro BS at t = 0" in the search table, (c) for outdoor use Only the base station was a valid outdoor base station, it can be seen that the class is "Class 2".

Therefore, (c) the degree of comprehensive similarity (general similarity) is calculated by comparing the grades of the (c) outdoor base station obtained at the corresponding location at the time point t = 0 on the search table with the reference tables (reference table # 1, reference table # 2, reference table # 3), respectively. do.

As a result, it can be seen that the similarity with reference table # ₁ is K ₁ , the similarity with reference table # 2 is 0, and the similarity with reference table # 3 is K ₁ .

Next, as a result of extracting a valid outdoor base station through the partial similarity calculation process at the corresponding position at time t = 1, as shown by the field "Macro BS at t = 1" in the search table, (a) The outdoor base station, (c) outdoor base station and (d) outdoor base station were valid outdoor base stations, (c) the outdoor base station is "Class 2", and (a), (d) the outdoor base station is "Class 4". It can be seen that.

Therefore, the degree of comprehensive similarity (general similarity) is calculated by comparing the rating of the outdoor base station acquired at the corresponding location at the time point t = 1 on the search table with the reference tables (reference table # 1, reference table # 2, reference table # 3).

As a result, the similarity with reference table # 1 is K ₁ + K ₂ + K ₀ , the similarity with reference table # 2 is K ₀ + K ₁ , and the similarity with reference table # 3 is K ₀ + K ₁ + K ₁ . Can be.

Next, as a result of extracting a valid outdoor base station through the partial similarity calculation process at the corresponding position at time t = 2, as can be seen from the field “Macro BS at t = 2” in the search table, (a) The outdoor base station, (c) outdoor base station and (d) outdoor base station were valid outdoor base stations, (a) the outdoor base station is "Class 2", (c) the outdoor base station is "Class 3", (d It can be seen that the grade of the outdoor base station is "Class 4".

Therefore, the degree of comprehensive similarity (general similarity) is calculated by comparing the ratings of the outdoor base stations acquired at the corresponding positions at the time point t = 2 on the search table with the reference tables (reference table # 1, reference table # 2, reference table # 3).

As a result, the similarity with reference table # 1 is K ₀ + K ₀ + K ₀ , the similarity with reference table # 2 is K ₂ + K ₁ , and the similarity with reference table # 3 is K ₀ + K ₁ + K ₀ . Can be.

Hereinafter, a process of calculating partial similarity through Equation 1 and a comprehensive similarity calculation process through Equation 2 will be described in detail.

이고,

는 기준표상의 옥외용 기지국 ID와 실제로 수신되는 옥외용 기지국 ID를 각각 나타낸다.here,

ego,

Denotes an outdoor base station ID and a base station ID that are actually received.

Moreover, the ratio of similarity is shown by the similarity coefficient (K).

Also, if the RSSI Class to which the ID of each outdoor base station in each reference table belongs and the RSSI Class to which the ID of the same outdoor base station in the search table are the same, K ₀ , K ₁ if one step is different, and K ₂ if there is a two step difference If three differences are found, K ₃ denotes each similarity. In this case, the similarity coefficient is K ₀ > K ₁ > K ₂ > K ₃ and the value has an exponential function.

After all, the similarity means the sum of the similarity coefficients for the received signal strength from each outdoor base station.

On the other hand, the method of the present invention as described above can be written in a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. The recording medium may include any type of computer readable recording medium.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention can be used for a portable internet system and the like.

1 is an exemplary diagram illustrating a handover scenario in a general cellular system.

FIG. 2 is an exemplary view illustrating a handover scenario in a portable Internet system composed of a general indoor / outdoor base station.

3 is an exemplary view of a conventional manual based searching method;

4 is an exemplary view of a conventional TA-based search method;

5 is an exemplary view of a conventional GPS-based search method;

6 is an exemplary view of a relationship based discovery method with a conventional neighbor cell;

7 is an exemplary view showing an arrangement of indoor / outdoor base stations in a portable Internet system to which the present invention is applied;

8 is an exemplary view illustrating a handover in a portable internet system to which the present invention is applied;

9 is an exemplary view of received signal strength profile information used for initiating an indoor base station search in a portable Internet terminal according to the present invention;

10 is a flowchart illustrating a method for initiating a search of an indoor base station in a portable Internet terminal according to the present invention;

11 is a diagram illustrating an embodiment of an indoor base station discovery start method in a portable Internet terminal according to the present invention.

* Explanation of symbols for the main parts of the drawings

1101: first indoor base station 1102: second indoor base station

1103: third indoor base station

Claims (8)

A method for initiating a search of an indoor base station in a portable internet terminal, Storing received signal strength profile information from the surrounding outdoor base station measured by the indoor base station to which the access is permitted; Extracting a valid outdoor base station by calculating partial similarity with respect to the surrounding outdoor base station; And Initiating a search for an indoor base station by calculating a comprehensive similarity for the valid outdoor base station; Initiating method of indoor base station search comprising a. The method of claim 1, The effective outdoor base station extraction step, Setting the class of the outdoor base station according to the received signal strength from the surrounding outdoor base station and recording the result in a table; Calculating at least one partial similarity by comparing the stored received signal strength profile information with the recorded grade of the outdoor base station; Confirming whether at least one partial similarity among the calculated partial similarities exceeds a threshold; Deleting the corresponding indoor base station information recorded in the table if the at least one partial similarity does not exceed a threshold as a result of the checking; And Maintaining the rating of the corresponding outdoor base station recorded in the table if the at least one partial similarity exceeds the threshold as a result of the checking; Initiating method of indoor base station search comprising a. The method of claim 2, The indoor base station discovery start step, Calculating at least one comprehensive similarity by comparing the grade of the outdoor base station recorded in the table with the stored received signal strength profile information; And Initiating a search of the indoor base station as at least one of the calculated similarities exceeds a reference value; Initiating method of indoor base station search comprising a. The method of claim 1, The receiving signal strength profile information storing step, A method of initiating an indoor base station search, which is received and stored from a core network as the portable internet terminal is activated. The method according to any one of claims 1 to 4, The partial similarity and the comprehensive similarity, A method of initiating an indoor base station search that is the sum of the similarity coefficients for the received signal strength from the outdoor base station. The method of claim 1, The received signal strength profile information, An at least one of outdoor base station information that can be communicated with each indoor base station, received signal strength (RSSI) from the outdoor base station, class classification information of the outdoor base station according to the received signal strength, and classifying reference information How to initiate a base station search. The method of claim 6, The received signal strength profile information, A method of initiating an indoor base station search further comprising frequency information used by the indoor base station. The method of claim 6, The class classification information, If the received signal strength is within a range that can be received in an inner cell area within an active serving cell, the corresponding outdoor base station is rated 1, and can be received in an outer cell area within an active serving cell. If the outdoor base station is a second-class, if not the active serving cell, but the serviceable range, the outdoor base station is three, and if only the pilot signal can be received, the outdoor base station is a fourth class.

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