JP5489232B2 - Mobile communication terminal - Google Patents

Description

  The present invention relates to a mobile communication terminal. In particular, the present invention relates to a mobile communication terminal that performs a handover between a base station of a macro cell and a base station of a femto cell.

  In recent years, mobile phones can be used indoors where macrocell radio waves are difficult to reach, such as in the home or office floor, or via communication traffic to a broadband line such as an optical fiber drawn into the home or office floor as a backbone. In some cases, a femtocell base station may be installed. The femtocell base station has a small radio wave transmission output. Therefore, the possibility of mutual interference is low, and identification information can be set relatively freely in the base station of each femtocell.

  By the way, as described in the background art of Patent Document 1, a base station of a wireless communication system broadcasts information on neighboring base stations that are candidates for handover. Neighboring base station information is listed and includes base station identification information and other information. For example, although the radio frequency channel number and the PN offset are included as identification information of the base station, the radio frequency channel number may be omitted if it is obvious or may include different information depending on the communication system. Normally, neighboring base station information is reported from a base station to a mobile phone using a common channel, but it is also possible to update neighboring base station information from a base station to a mobile phone using an occupied channel. There is a restriction on the amount of information that can be transmitted on the common channel or the occupied channel, and the number of base stations included in the neighboring base station information is limited. Using this neighboring base station information, the mobile phone searches for or identifies neighboring base stations.

  The number of neighboring base stations that can be reported by the base station is limited. For example, in the Cdma2000 system, the number is 40. Generally, a macro cell base station installed outdoors has a service area radius of the order of km, so that an infinite number of femto cell base stations can be installed in the service area. It is impossible for the base station to report all these femtocell base stations as separate handover candidates.

  Among a finite number of base stations to be notified as handover candidates, a predetermined number of base stations are used as femto cell base stations, thereby enabling handover from a macro cell base station to a femto cell base station. The technique is disclosed in Patent Document 1. For example, a base station determines a set of a frequency channel number and a PN offset value in advance, assigns the set value to the base station of the femtocell, and informs the base station of this set value as a handover candidate. Thus, the mobile phone can be handed over from the macro cell base station to the femto cell base station.

  FIG. 9 shows an example of a usage environment of a general wireless system 900. The radio system 900 includes a plurality of macro cell base stations 910a to 910c (hereinafter collectively referred to as macro cell base stations 910) and a plurality of femto cell base stations 920a to 920c (hereinafter collectively referred to as femto cell base stations 920). ). Each femtocell base station 920 is located within the service area of the macrocell base station 910a. A base station 910 for each macro cell and a base station 920 for each femto cell are connected by a network 930. A mobile phone 990 is located in the vicinity of the macro cell base station 910a and the femto cell base station 920a.

  In the example of FIG. 9, some of the neighboring base station information is allocated as a femtocell base station 920 by the macrocell base station 910a, and the neighboring base station information including information on the femtocell base station 920 is assigned to the macrocell base station 920a. The station 910a broadcasts and sets information of the femtocell base station 920 in the femtocell base stations 920a to 920c. The cellular phone 990 can be handed over from the base station 910a of the macro cell to the base stations 920a to 920c of each femto cell without being aware of whether it is the base station 920 of the femto cell.

  Hereinafter, information broadcast from the base station will be described. Information broadcast from the base station is not limited to neighboring base stations that are candidates for handover. For example, the base station of Cdma2000 informs the latitude and longitude of the position where it is installed, informs the value that is the source of the diffusion code, and calculates the positioning of the mobile phone as described in Patent Document 2. Notify the value to be used, etc. By using these broadcast information received from the base station, the mobile phone provides an appropriate service to the end user.

  The base station broadcasts a reference signal, and this reference signal can be received by the mobile phone without handover. The mobile phone knows the presence of the neighboring base station by checking whether this reference signal matches the neighboring base station identification information. Most of the other broadcast information of the base station can be received only after the handover.

  In the following, description will be given of omission of reception of broadcast information implemented in a mobile phone. The process in which the mobile phone receives broadcast information from the base station that has been handed over consumes power. In places where the same level of reception sensitivity can be obtained from a plurality of base stations, the mobile phone repeats handovers in and out of the same base station due to minor fluctuations in radio waves, and consumes power each time. In order to reduce this power consumption, the following method is usually implemented.

  The mobile phone stores the notification information received from the base station in a storage device so that it can be searched using information for identifying the base station. The handover process is performed as follows. First, the mobile phone uses the neighboring base station information to search for a handover destination and decide to perform handover. Then, the communication means is switched to the handover destination. Then, the identification information of the handover destination is confirmed. Then, the storage device is searched using the identification information of the handover destination. If the handover destination identification information does not exist in the storage device, it is determined that re-reception of the broadcast information is necessary, the mobile phone receives the broadcast information from the base station, stores the broadcast information in the storage device, Necessary processing is performed in the handover destination base station according to the broadcast information. If the identification information of the handover destination exists in the storage device, it is determined that the re-reception of the broadcast information is not necessary, and the process of receiving the broadcast information from the base station and storing it in the storage device can be omitted. The power consumption necessary for the processing can be saved.

  As information for identifying the base station used here, information that is clear before receiving broadcast information immediately after handover, such as a reference signal, is desirable. This is because, if information that cannot be obtained without receiving broadcast information is necessary, the purpose of omitting reception of broadcast information cannot be achieved. Therefore, as information for identifying a base station, for example, a set of a frequency channel number and a PN offset is used in the same way as a handover candidate.

  The base station identification information is set not to be the same between neighboring base stations. Referring to FIG. 9, if the PN offset of the base station 910a of the macro cell is PNA, PNBs having different PN offsets of the base station 910b of the adjacent macro cell are set. The macro cell base station 910c far from the macro cell base station 910a can use the same PNA as the macro cell base station 910a. Although the same identification information can be used between distant base stations such as the macro cell base station 910a and the macro cell base station 910c, it takes time for the mobile phone 990 to move between such base stations. By adding an expiration date to the notification information stored in the storage device of the mobile phone 990 and determining whether the expiration date has passed in the process of determining whether the notification information needs to be received or not As a result, the mobile phone 990 does not confuse the macro cell base station 910a with the macro cell base station 920c.

JP 2010-0568857 A Japanese Patent No. 4032684

  However, when a known handover method and a method for omitting reception of broadcast information are combined, a user having a mobile phone moves and moves from a femtocell base station to another femtocell base station. If over is repeated, various problems arise.

  For example, in a known handover method from a macro cell base station to a femto cell base station, an infinite number of femto cell base stations are represented by a small number of handover candidates, so that an unspecified number of femto cell base stations are common. Will be used.

  Referring to FIG. 9, since there are an infinite number of femtocell base stations 920 in the service area of the macrocell base station 910a, the femtocell base station 920c having the same identification information as the femtocell base station 920a It may exist in the vicinity of the cell base station 920a. Initially, it is assumed that the mobile phone 990 is waiting at the base station 920a of the femtocell. When the cellular phone 990 leaves the femtocell base station 920a, the output of the femtocell base station 920 is weak, so that the mobile phone 990 is handed over to the macrocell base station 910 and then handed over to the femtocell base station 920b. Alternatively, the handover is performed directly from the femtocell base station 920a to the femtocell base station 920b. A problem occurs when the mobile phone further attempts to reach the femtocell base station 920c by repeating the handover.

  When the mobile phone is handed over to the femtocell base station 920c, the mobile phone searches its own storage device using the identification information of the femtocell base station 920c, and informs the femtocell base station 920a having the same identification information. Information hits. Since the femtocell base station 920a and the femtocell base station 920c exist in the vicinity, it does not take much time for the mobile phone to move back and forth between them, and the mobile phone stores the femtocell base station 920a stored in the storage device. The broadcast information has not expired. Then, the mobile phone misidentifies the femtocell base station 920c as the femtocell base station 920a, and the mobile phone omits reception of broadcast information from the femtocell base station 920c. However, since it is actually a different base station, the broadcast information received from the femtocell base station 920a on the storage device is different from the broadcast information received from the femtocell base station 920c that could not be received. . Thus, for example, the mobile phone misuses the latitude and longitude of the femtocell base station 920a as those of the femtocell base station 920c in the location information service.

  In order to avoid this problem, a handover from a femtocell base station 920 to another macrocell base station 910 or another femtocell base station 920 is also prohibited. Is it necessary to receive broadcast information when waiting for the femtocell base station 920c when the received broadcast information is deleted when it goes out of service when it moves away from the femtocell base station 920a? It is determined that the broadcast information needs to be received by determining whether or not, and the broadcast information of the femtocell base station 920c can be correctly received. However, this method has a new problem such as missing an incoming call because it goes out of service area.

  Furthermore, in the known technology, since the base station of the macro cell and the base station of the femto cell are informed as the neighbor base station information without being distinguished, the following problems occur when using the neighbor base station information in the positioning calculation: was there.

  As described in Patent Document 2, the position of the base station is fixed, and the information received from each neighboring base station is processed by a server on the network to calculate the position of the mobile phone. Things are happening. Processing of the mobile phone in this positioning system will be described. The mobile phone prepares information on neighboring base stations. This can use neighboring base station information broadcast from the base station. Next, a distance is calculated using a reference signal received from a neighboring base station, and a measurement result is created by comparing with the neighboring base station information. Subsequently, the measurement result is transmitted to a server on the network, and the server calculates the position of the mobile phone. Finally, the mobile phone location is received from the server.

  In this positioning system, the positions of neighboring base stations need to be registered in the server in advance. However, it is difficult to manage femtocell base stations on a server because an unspecified number of base stations are installed or stopped in a free place. In addition, since the neighboring base stations that can receive radio waves from a mobile phone located in a certain base station are limited, the combinations of base stations from which the mobile phone can receive radio waves are also limited. The position can be predicted. However, since there are an unspecified number of femtocell base stations in the service area of the macrocell base station, the server cannot distinguish which femtocell base station is actually capable of receiving radio waves. . Under such circumstances, it is an obstacle to provide the location information service.

  In order to solve the above problems, according to a first embodiment of the present invention, a mobile communication terminal that performs a handover between a base station of a macro cell and a base station of a femto cell, the mobile communication terminal A computing device that controls the operation; the computing device determines whether the handover destination base station is a femtocell base station; and determines that the handover destination base station is a femtocell base station In this case, broadcast information is received from the handover destination base station, and if it is determined that the handover destination base station is not a femtocell base station, broadcast information is not received from the handover destination base station.

  In addition, as described above, the summary of the invention does not enumerate all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  As is apparent from the above description, in the present invention, it is determined whether or not the handover destination base station is a femtocell base station, and the handover destination base station is a femtocell base station. If it is determined that the correct broadcast information can be received without confusing the broadcast information with other femtocell base stations, and the handover destination base station is determined not to be a femtocell base station, Since the broadcast information is not received when the handover destination base station is a macro cell base station, the power consumption of the processing can be reduced.

It is a figure which shows an example of the block configuration of the mobile telephone 100 which concerns on one Embodiment. It is a figure which shows an example of the data stored in the information storage area 121 in a table format. It is a figure which shows an example of the operation | movement flow of the calculating apparatus 130 of the mobile telephone 100 when determining whether a base station is a base station of a femtocell. It is a figure which shows an example of the operation | movement flow of the arithmetic unit 130 of the mobile telephone 100 when performing a hand-over. It is a figure which shows an example of the operation | movement flow of the calculating apparatus 130 of the mobile telephone 100 when performing the positioning process using a neighboring base station. It is a figure which shows another example of the data stored in the information storage area 121 in a table format. It is a figure which shows another example of the operation | movement flow of the calculating apparatus 130 of the mobile telephone 100 when determining whether a base station is a base station of a femtocell. It is a figure which shows another example of the operation | movement flow of the arithmetic unit 130 of the mobile telephone 100 when performing the positioning process using a neighboring base station. 1 is a diagram illustrating an example of a usage environment of a general wireless system 900. FIG.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and are combinations of features described in the embodiments. Not all are essential to the solution of the invention.

  FIG. 1 shows an example of a block configuration of a mobile phone 100 according to an embodiment. The mobile phone 100 performs a handover between a macro cell base station and a femto cell base station. The mobile phone 100 may be an example of the “mobile communication terminal” in the present invention.

  The mobile phone 100 includes a wireless device 110, a storage device 120, an arithmetic device 130, a display device 140, an input device 150, and a power supply device 160. These devices of the mobile phone 100 are electrically connected to each other.

  Radio apparatus 110 receives and demodulates radio waves from a macro cell base station or a femto cell base station. The radio apparatus 110 modulates and transmits radio waves to a macro cell base station or a femto cell base station. Further, the wireless device 110 may have a function of receiving a GPS (Global Positioning System) signal. The storage device 120 stores various programs and data necessary for operating the mobile phone 100. The arithmetic device 130 controls the operation of the mobile phone 100. The display device 140 notifies the user of the mobile phone 100 of necessary information. The input device 150 receives an instruction from the user of the mobile phone 100. The power supply device 160 supplies power to the entire mobile phone 100.

  In addition, an information storage area 121 is provided in the storage device 120, and identification information expressing that it is a femtocell base station is stored in the information storage area 121. The information storage area 121 representing the femtocell base station will be described in detail as follows. This information storage area 121 may not be rewritable by execution of software. In this case, identification information representing a predetermined femtocell base station is stored in the information storage area 121 by the manufacturer of the mobile phone 100. Stored.

  FIG. 2 shows an example of data stored in the information storage area 121 in a table format. In the best mode of the present invention, this information storage area 121 is arranged in a part of the data area. If it is Cdma2000, it has the structure shown in FIG. 2 and can be rewritten by executing software. The user can change the identification information representing the femtocell base station by operating the input device 150 while following the instructions of the display device 140, or the mobile phone 100 can receive information identifying the femtocell base station from the communication network. For example, the identification information representing the femtocell base station obtained can be changed. The information storage area 121 is preferably a part of the data area, but may be a part of software.

  FIG. 3 shows an example of an operation flow of the arithmetic device 130 of the mobile phone 100 when determining whether or not the base station is a femtocell base station. First, the computing device 130 of the mobile phone 100 stores a set of identification information of a base station to be determined in a variable A (S101). Then, the arithmetic device 130 extracts a set from the identification information list representing the base station of the femtocell illustrated in FIG. 2, and stores it in a variable B (S102). Then, the arithmetic unit 130 determines whether or not the values of A and B match (S103). If they match (S103: Yes), the arithmetic unit 130 sets the determination result as a femtocell base station (S104). If they do not match (S103: No), the arithmetic unit 130 extracts the next set from the identification information list representing the base station of the femtocell illustrated in FIG. 2 and stores it in the variable B (S105). . Then, the arithmetic unit 130 determines whether or not there is a next set to be stored in the variable B (S106). If the next set does not exist (S106: Yes), the determination result is a femtocell. It is set not to be a base station (S107). If the next set exists (S106: No), the arithmetic unit 130 continues the processing from step S103.

  FIG. 4 shows an example of an operation flow of the arithmetic device 130 of the mobile phone 100 when performing a handover. First, the computing device 130 of the mobile phone 100 searches for a handover destination using the neighboring base station information and decides to perform handover (S201). Then, the arithmetic device 130 switches the communication means to the handover destination (S202). Then, the arithmetic device 130 confirms the handover destination identification information (S203). Then, the arithmetic device 130 searches the storage device 120 using the handover destination identification information (S204). Then, the computing device 130 determines whether or not the search result is a femtocell base station by the process shown in FIG. 3 (S205). If it is determined that it is a femtocell base station (S205: Yes), that is, the handover destination is a femtocell base station, the arithmetic unit 130 receives broadcast information from the base station (S207), and the storage device The broadcast information is stored in 120 (S208), and necessary processing is performed in the handover destination base station according to the broadcast information (S209). In this way, the mobile phone 100 can prevent the confusion of the femtocell base stations and reliably receive correct information. If it is determined that the base station is not a femtocell base station (S205: No), that is, the handover destination is a macrocell base station, the arithmetic unit 130 determines whether it is necessary to re-receive broadcast information. (S206). If the identification information of the handover destination does not exist in the storage device, it is determined that the broadcast information needs to be received again (S206: Yes), and the arithmetic device 130 receives the broadcast information from the base station (S207) and stores it. The broadcast information is stored in the device 120 (S208), and necessary processing is performed in the handover destination base station according to the broadcast information (S209). If the identification information of the handover destination exists in the storage device, it is determined that re-reception of the broadcast information is not necessary (S206: No), and step S207 and step S208 can be omitted. Can save power consumption.

  FIG. 5 shows an example of an operation flow of the arithmetic device 130 of the mobile phone 100 when performing positioning processing using a neighboring base station. First, the computing device 130 of the mobile phone 100 prepares information on neighboring base stations (S301). This can use neighboring base station information broadcast from the base station. Then, the arithmetic device 130 calculates a distance using a reference signal received from a neighboring base station, and creates a measurement result against the neighboring base station information (S302). Then, the arithmetic device 130 extracts the measurement result of one base station from the distance measurement results of neighboring base stations (S303). The measurement result of this one base station includes the identification information of the base station and the distance information thereof, and the arithmetic unit 130 uses the identification information of this base station to perform the processing shown in FIG. If it is determined that the base station is a femtocell base station, the measurement result of this one base station is discarded (S304). Then, the arithmetic unit 130 determines whether or not all the measurement results have been scanned (S305), and if there is an unscanned measurement result (S305: No), the measurement result of the next one base station is extracted (S306). ), Step S304 and subsequent steps are repeated. If it is determined that all have been scanned (S305: Yes), the measurement result is transmitted to a server on the network (S307), and the server calculates the position of the terminal. Then, the arithmetic device 130 receives the position of the mobile phone 100 from the server (S308). In this manner, it is realized to exclude the positioning result of the femtocell base station from the positioning result.

  As described above, the present invention has the following effects. The first effect is that the mobile phone 100 has means for determining whether or not the handover destination is a femtocell base station, so when receiving a handover to a macrocell base station, reception of broadcast information is omitted. Thus, when handing over to a femtocell base station while reducing power consumption, it is possible to receive correct broadcast information without confusion with other femtocell base stations.

  The second effect is that since the mobile phone 100 has means for determining whether the neighboring base station is a femtocell base station, positioning is performed by excluding the femtocell base station that becomes an obstacle in the positioning calculation. Be able to.

  The basic configuration of the identification information list representing the base station of the femtocell is as described with reference to FIG. 2, but the effects of the present invention can be obtained even with the following differences. If the radio frequency channel number is obvious, the radio frequency channel number may be omitted. Or even if it is communication systems other than Cdma2000, this invention can be implemented by using the combination of the information which can identify a base station.

  FIG. 6 shows another example of data stored in the information storage area 121 in a table format. In the expression of FIG. 6, it can be determined that the step S103 described in FIG. 3 matches if the PN offset is a value between the lower limit and the upper limit, and similarly, the upper limit is set to the radio frequency number in the structure of FIG. If the radio frequency number is between the upper limit and the lower limit, it can be determined that they match.

  FIG. 7 shows another example of the operation flow of the arithmetic device 130 of the mobile phone 100 when determining whether or not the base station is a femtocell base station. In this operation flow, the identification information representing the femtocell base station determined in advance is not a value but the order of neighboring base station information broadcast by the base station.

  First, the arithmetic device 130 of the mobile phone 100 stores the identification information of the base station to be determined in the variable A (S401). Then, the arithmetic unit 130 searches for the value of the variable A using the neighboring base station information reported by the base station (S402). Then, the arithmetic unit 130 determines whether or not the value of the variable A is included in the neighboring base station information broadcast by the base station (S403), and if not included (S403: No), the base whose determination result is to be determined. The station is set not to be a femtocell base station (S407). If included (S403: Yes), the arithmetic unit 130 confirms the order of the variable A on the neighboring base station list (S404), and whether this order matches the order of information of the base station of the femtocell. (S405), if they do not match (S405: No), the base station from which the determination result is to be determined is not a femtocell base station (S407). If they match (S405: Yes), the arithmetic unit 130 sets the determination result as a femtocell base station (S406).

  As described above, the process of determining whether or not a certain base station is a femtocell base station can be realized by software in accordance with a predetermined method for representing a femtocell base station.

  FIG. 8 shows another example of the operation flow of the arithmetic device 130 of the mobile phone 100 when performing the positioning process using the neighboring base station. First, the computing device 130 of the mobile phone 100 prepares information on neighboring base stations (S501). This can use neighboring base station information broadcast from the base station. Then, the arithmetic unit 130 extracts the first one from the neighboring base station identification information list for positioning (S502). Then, the arithmetic unit 130 determines whether or not this base station identification information is a femtocell base station by the processing shown in FIGS. 3 and 7, and if it is a femtocell base station, this base station identification information. Is deleted from the neighboring base station identification information list for positioning (S503). Then, the arithmetic unit 130 determines whether or not all the neighboring base station information lists for positioning have been scanned (S504). If there is an unscanned neighboring base station (S504: No), the next neighboring base station The next one is extracted from the information identification list (S505), and the processing after step S503 is continued. If there is no unscanned neighboring base station (S504: Yes), the positioning process is continued (S506 to S508). As a result, positioning can be performed only for normal neighboring base stations excluding the base station of the femtocell.

  For example, the last few may be femtocell base stations, and the nth may be a femtocell base station. FIG. 8 shows an example in which the identification information representing the femtocell base station determined in advance is a value. However, in the case of determining that the n-th base station is a femtocell base station, the processing in steps S502 to S505 is performed. The same effect can be obtained by replacing with the process of simply deleting the nth.

  Moreover, although the positioning process of the mobile phone 100 has been described as an example, the process of excluding the femtocell base station from the neighboring base station information may be applied to other calculations.

  The handover process described with reference to FIG. 4 and the positioning process described with reference to FIG. 5 are independent processes, but it is preferable to perform both, but only one may be performed.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Cellular phone 110 Radio | wireless apparatus 120 Memory | storage device 130 Arithmetic apparatus 140 Display apparatus 150 Input apparatus 160 Power supply apparatus

Claims (4)

A mobile communication terminal that performs a handover between a macro cell base station and a femto cell base station,
An arithmetic device for controlling the operation of the mobile communication terminal;
The computing device determines whether or not the handover destination base station is a femtocell base station, and determines that the handover destination base station is a femtocell base station. A mobile communication terminal which receives broadcast information from a base station and does not receive broadcast information from the handover destination base station when it is determined that the handover destination base station is not a femtocell base station .   In determining whether or not the handover destination base station is a femtocell base station, the arithmetic device represents the identification information of the handover destination base station and a predetermined femtocell base station. 2. The mobile communication terminal according to claim 1, wherein it is determined whether or not the handover destination base station is a femtocell base station by comparing with identification information to be transmitted.   The calculation device according to claim 1 or 2, wherein the calculation device performs calculation using the neighboring base station information received from the base station, excluding information on a femtocell base station from neighboring base stations. 2. The mobile communication terminal according to 2.   The mobile communication terminal according to claim 3, wherein the calculation device calculates positioning of the mobile communication terminal as the calculation.

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