JP2005184160A - Wireless communication system, mobile information terminal, handover solution method used for the same, and program thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile information terminal suppressing consumption of current and quickly carrying out switching of a handover to a base station with high quality. <P>SOLUTION: In the case of carrying out handover, a main control section 14 acquires a current time from a real time clock 19 and the main control section 14 acquires an in-zone cell corresponding to the current time on the basis of handover history data stored in a RAM 16. The main control section 14 uses a code whose number of occurrence times is a prescribed value or over as valid data and utilizes only the code of the valid data for code of a prediction cell. Upon the receipt of notice information, when the code of the prediction cell exists in information of surrounding cells received by the notice information, the main control section 14 monitors only the reception power of the prediction cell. When the reception power of a base station in the prediction cell is greater than the reception power of the base station in the in-zone cell, the main control section 14 transmits a request of handover to the base station of the in-zone cell. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radio communication system, a portable information terminal device, a handover solution used therefor, and a program therefor, and more particularly to a handover solution method for a mobile phone used in a cellular radio communication system.

  2. Description of the Related Art Conventionally, in a cellular radio communication system, an area for providing communication services is divided into several cells, base stations are installed in each cell, and radio quality is improved when a mobile station (hereinafter referred to as a terminal) moves. By switching to a good base station, control is performed to ensure the best standby state of the terminal.

  In addition, the terminal continues the connection state with the base station of the cell in which the terminal is present (the visited cell), and at the same time, monitors the wireless state of a plurality of cells around the visited cell. The terminal receives the pilot signal of the control channel transmitted from the neighboring base station based on the neighboring cell code included in the broadcast information of the serving cell.

  The terminal measures the received power of the pilot signal, determines the base station with the largest received power as a destination base station candidate, and transmits a base station switching request to the base station of the serving cell.

  The base station determines whether or not to perform switching based on a switching request from the terminal, and switches the base station when determining that it should be performed. This operation is called handover. At this time, since the terminal performs handover to one cell despite monitoring a plurality of cells, the monitoring operation of cells other than the handover destination is wasted.

  Also, cells visited by a terminal usually show a certain tendency depending on the behavior pattern of the owner of the terminal. For example, a fixed route is taken at a substantially constant time for the movement from home to work, and the terminal also performs monitoring and handover of neighboring cells according to a substantially constant rule.

  For this reason, in the conventional method, there are base stations where location registration is not performed even though the cell is monitored while the terminal is moving. In order to solve this problem, the terminal stores the time at the time of handover execution, the code of the handover destination cell, and the number of times, and predicts the next handover destination base station based on these data.

  The broadcast cell broadcast information includes a prediction cell code. When a prediction cell is detected as a result of monitoring neighboring cells, monitoring of other cells is stopped. When the prediction is successful and the communication state of the monitored cell becomes better than that of the cell whose current location is registered, the terminal transmits a handover request to the base station of the serving cell.

  The base station makes a handover decision based on the handover request from the terminal, and executes the handover when determining that it should be executed. If the prediction is lost and the communication state of the cell being monitored has deteriorated, the terminal resumes monitoring of neighboring cells and performs handover based on the conventional method.

JP 2002-232929 A JP 2001-119742 A

  In the above-described conventional cellular radio communication system, when the terminal moves between a plurality of cells, the communication state of the neighboring cells of the cell where the terminal is located is monitored. However, the terminal can be handed over when moving. A base station is one of them, and there are many cells that have been monitored but are not actually handed over.

  Also, the movement pattern of the terminal user usually shows a certain tendency. For example, even when moving from home to work, when a train or bus is used, it regularly passes on the route.

  In this case, handover is always performed from a base station near the route to a base station near the route with a certain pattern. Nevertheless, since the terminal constantly monitors neighboring cells, the current consumption of the terminal is consumed wastefully and the handover operation takes time.

  Accordingly, an object of the present invention is to solve the above-described problems, suppress current consumption, and quickly switch over a handover to a high-quality base station. The object is to provide a handover solution and a program therefor.

The wireless communication system according to the present invention is configured to select a base station with the largest received power from among neighboring base stations based on a code of a neighboring cell included in broadcast information of a serving cell in a portable information terminal device. A wireless communication system for transmitting a handover request to the base station of the serving cell,
Storage means for storing a history of handover, means for predicting a predicted cell with a high probability of handover as a handover destination cell based on the history of the storage means, and monitoring means for monitoring only the predicted cell It is provided in the portable information terminal device.

The mobile information terminal device according to the present invention determines the base station with the highest received power from the neighboring base stations as a destination base station candidate based on the neighboring cell code included in the broadcast cell broadcast information, A portable information terminal device that transmits a handover request to a base station of the serving cell,
Storage means for storing a history of handover, means for predicting a predicted cell having a high probability of handover as a handover destination cell based on the history of the storage means, and monitoring means for monitoring only the predicted cell ing.

  According to the handover solution method of the present invention, a portable information terminal device selects a base station with the highest received power from neighboring base stations based on a code of a neighboring cell included in broadcast information of a serving cell. A handover communication method of a wireless communication system for transmitting a handover request to a base station of the serving cell, and storing a handover history in a storage means on the portable information terminal device side; Predicting a predicted cell having a high probability of handover as a handover destination cell based on the history of the storage means, and monitoring only the predicted cell.

  A program for a handover solution according to the present invention is a mobile information terminal device that selects a base station with the highest received power from neighboring base stations based on a code of a neighboring cell included in broadcast information of a serving cell. A program for determining a station candidate and transmitting a handover request to a base station of the serving cell, a method for resolving a handover in a wireless communication system, the computer storing a handover history in a storage unit, A process of predicting a predicted cell with a high probability of handover as a handover destination cell based on the history of the storage means and a process of monitoring only the predicted cell are executed.

  That is, the wireless communication system of the present invention predicts a handover destination cell based on a history of handover of a terminal including time information in a portable information terminal device incorporating a wireless communication control unit, and has a low probability of handover. By not performing monitoring, a means for reducing current consumption of the portable information terminal device is realized.

  As a result, the wireless communication system of the present invention can predict the handover destination cell from the serving cell based on the past handover history corresponding to the current time. It becomes possible to focus on.

  Therefore, in the wireless communication system of the present invention, by not monitoring a cell with a low probability of handover, it is possible to suppress the current consumption of the portable information terminal device and speed up the switching of the handover to a high-quality base station. It becomes.

  By adopting the configuration and operation as described below, the present invention can suppress the current consumption, and the effect that the switching of the handover to the base station with good quality can be accelerated.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a mobile phone according to an embodiment of the present invention. In FIG. 1, a mobile phone (portable information terminal device) 1 includes an antenna 11, a radio transmission / reception unit 12, a radio data control unit 13, a main control unit 14, a program ROM (read only memory) 15, and a RAM (random). (Access memory) 16, a display unit 17, an operation input unit 18, a real-time clock 19, a sound processing unit 20, a speaker 21, a microphone 22, and a receiver 23.

  The antenna 11 transmits / receives a radio signal between a base station (not shown) and the mobile phone 1, and the radio transmitter / receiver 12 modulates / demodulates the transmitted / received radio signal and performs an operation according to the radio signal from the base station. The wireless data control unit 13 receives transmission data from the main control unit 14 according to its own wireless information registered in advance, sends it to the wireless transmission / reception unit 12, and provides the main control unit 14 with data received via radio.

  The program ROM 15 stores a program executed by the main control unit 14, and the RAM 16 stores handover history data and the like. The display unit 17 displays a telephone number, a clock, and the like, and the operation input unit 18 is a key switch for a user to perform various operations such as inputting a telephone number.

  The real time clock 19 supplies time information to the main control unit 14. The voice processing unit 20 converts a voice signal, the speaker 21 outputs a ring tone, and the microphone 22 inputs a user's voice. The receiver 23 outputs the other party's voice.

  FIG. 2 is a diagram showing an outline of a cellular radio communication system according to an embodiment of the present invention. In FIG. 2, in a base station arrangement such as base station (A) 2-1 to base station (J) 2-10, in a service area configured as cell (A) 101 to cell (J) 110 The state in which the terminal 1 is moving along the movement route 112 is shown. The terminal 1 has the same configuration as that of the mobile phone 1 described above.

  FIG. 3 is a flowchart showing an example of handover processing in the terminal 1 of FIG. The handover process in the terminal 1 will be described with reference to FIGS. Here, the terminal 1 is located in the cell (D) 104 [hereinafter referred to as the serving cell (D) 104], the received power of the serving cell (D) 104 is Pd, and the serving cell (D) 104 Cell (A) 101 received power Pda, cell (B) 102 received power Pdb, cell (C) 103 received power Pdc, cell (E) 105 received power Pde, cell (F) The received power of 106 is Pdf, and the received power of the cell (G) 107 is Pdg.

  First, the terminal 1 selects a base station [base station (D) 2-4 in this embodiment] having the highest received power from the base stations (A) 2-1 to (J) 2-10, A radio channel is established with the selected base station (D) 2-4.

  At that time, the terminal 1 receives broadcast information to establish a radio channel with the base station (D) 2-4 (step S1 in FIG. 3). The broadcast information includes cell (A) 101, cell (B) 102, cell (C) 103, cell (E) 105, cell (F) 106, cell ( G) 107 is included, and the terminal 1 has cell (A) 101, cell (B) 102, cell (C) 103, cell (E) 105, cell (F) 106, cell (G) 107, respectively. Monitoring of the received power Pda, Pdb, Pdc, Pde, Pdf, Pdg is started (steps S2, S5, S8, S11, S14, S17 in FIG. 3).

  When the terminal 1 moves along the moving route 112 and reaches the point 111, the received power Pdg of the cell G becomes higher than the received power Pd of the serving cell (D) 104 (step S18 in FIG. 3). The terminal 1 transmits a handover request signal to the base station (D) 2-4. The base station (D) 2-4 determines whether or not to execute the handover based on the handover request signal from the terminal 1, and executes the handover when determining that it should be executed (step S19 in FIG. 3).

  Similarly, in the above system, the cell (A) 101, the cell (B) 102, the cell (C) 103, the cell (E) 105, and the cell (F) 106 are respectively determined from the received power Pd of the serving cell (D) 104. When the received power Pda, Pdb, Pdc, Pde, Pdf, Pdg of the terminal 1 increases (steps S3, S6, S9, S12, S15 in FIG. 3), the terminal 1 sends a handover request signal to the base station (D) 2-4. To send. The base station (D) 2-4 determines whether or not to execute the handover based on the handover request signal from the terminal 1, and executes the handover when determining that it should be executed (steps S4, S7, and S10 in FIG. 3). , S13, S16).

  By the way, in such a system, while being in the cell (D) 104, the terminal 1 always has the cell (A) 101, the cell (B) 102, the cell (C) 103, the cell (E) 105, The received power Pda, Pdb, Pdc, Pde, Pdf, and Pdg of each of the cell (F) 106 and the cell (G) 107 are monitored (steps S2, S5, S8, S11, S14, and S17 in FIG. 3).

  However, when the terminal 1 moves along the movement route 112, the handover occurs only between the base station (D) 2-1 and the base station (G) 2-7. In other words, the radio establishment state is not disconnected without monitoring the cell (A) 101, the cell (B) 102, the cell (C) 103, the cell (E) 105, and the cell (F) 106. In addition, by monitoring the base station that is not handed over, the current consumption of the terminal 1 increases and it takes time to perform a handover operation to a base station with good quality.

  FIG. 4 is a diagram illustrating a storage example of a serving cell list according to an embodiment of the present invention. In FIG. 4, the cell list {“cell A [100], cell D [80], cell G [70], cell X [1],...”, “Cell D [90], cell G [30 ], Cell A [20], cell Y [1], ... "," cell G [90], cell D [20], cell A [10], cell Z [1], ... "} It is stored together with time data (“7:50”, “8:00”, “8:10”).

  FIG. 5 is a flowchart showing a handover process according to an embodiment of the present invention. A handover process according to an embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, FIG. 4, and FIG. The processing shown in FIG. 5 is realized by the main control unit 14 executing the program in the program ROM 15.

  First, when the terminal 1 moves on the route 112 and is handed over from the cell (A) 101 to the cell (D) 104, the main control unit 14 acquires the current time (8:00) from the real-time clock 19 ( FIG. 5 steps S21 and S22).

  Next, the main control unit 14 determines from the handover history data stored in the RAM 16 the code and frequency ([]) of the serving cell (cell D, cell G, cell A, cell Y) corresponding to the current time (8:00). (See Fig. 4). The main control unit 14 uses those codes whose number of times is equal to or greater than a certain value as valid data, and uses only the codes of valid data as the prediction cell codes (step S23 in FIG. 5).

  When the main control unit 14 receives the broadcast information (step S24 in FIG. 5), the main control unit 14 confirms whether the code of the predicted cell is present in the information on the neighboring cells received in the broadcast information (S25 and S26 in FIG. 5). In this embodiment, it is assumed that the code of the cell (G) 107 exists in the broadcast information. When the code of the predicted cell is present in the broadcast information, the main control unit 14 monitors only the received power Pdg of the predicted cell (step S27 in FIG. 5).

  When the terminal 1 moves on the moving route 112, the received power Pdg of the base station (G) 2-7 that is the predicted cell is higher than the received power Pd of the base station (D) 2-4 that is the serving cell. (Step S28 in FIG. 5), the main control unit 14 transmits a handover request to the base station (D) 2-4. The base station (D) makes a handover decision in response to the request from the terminal 1, and if it judges that it should be executed, makes a handover to the predicted cell (G) 107 (step S29 in FIG. 5).

  When the handover is completed, the terminal 1 records the handover completion time, the handover destination cell code, and the number of handovers in the RAM 16 as handover history information (step S30 in FIG. 5).

  Further, when the reception power Pdg of the prediction cell (G) 107 decreases below a certain level Pc while only the reception power Pdg of the prediction cell (G) 107 is being monitored (step S31 in FIG. 5), the main control unit 14 monitors neighboring cells according to neighboring cell information included in the broadcast information, and performs handover based on the monitoring result (step S32 in FIG. 5), so that the user has moved on a route different from the traveling route 112. Even in this case, the standby state can be secured.

  At this time, the main control unit 14 records the handover completion time, the handover destination cell code, and the number of handovers in the RAM 16 as handover history information (step S33 in FIG. 5).

  Further, when the predicted cell does not exist as a result of searching for the predicted cell (step S25 in FIG. 5), the main control unit 14 monitors the neighboring cells based on the content of the broadcast information according to the conventional method, and the monitoring result The base station is switched based on (step S32 in FIG. 5).

  Also in this case, when the handover is completed, the main control unit 14 records the handover completion time, the handover destination cell code, and the number of handovers in the RAM 16 as handover history information (step S33 in FIG. 5).

  As described above, in this embodiment, since a handover destination cell from a serving cell can be predicted based on a past handover history corresponding to the current time, monitoring of neighboring cells can be limited to only the predicted cell. it can.

  As a result, in this embodiment, by not monitoring a cell with a low probability of handover, the current consumption of the terminal 1 can be suppressed, and switching to a handover to a high-quality base station can be accelerated. .

It is a block diagram which shows the structure of the mobile telephone by one Example of this invention. It is a figure which shows the outline | summary of the cellular radio | wireless communications system by one Example of this invention. 3 is a flowchart showing an example of a handover process in the terminal of FIG. It is a figure which shows the example of a storage of the serving cell list by one Example of this invention. 5 is a flowchart illustrating a handover process according to an embodiment of the present invention.

Explanation of symbols

1 Mobile phone (terminal)
2-1 to 2-10 Base stations (A) to (J)
11 Antenna
12 Wireless transceiver
13 Wireless data control unit
14 Main control unit
15 Program ROM
16 RAM
17 Display
18 Operation input section
19 Real time clock
20 Audio processing part
21 Speaker
22 microphone
23 receivers 101-110 cells (A)-(J)
111 points
112 Travel Route

Claims (19)

In the portable information terminal device, a base station with the largest received power is determined as a destination base station candidate from the surrounding base stations based on the codes of neighboring cells included in the broadcast information of the serving cell, and the serving cell A wireless communication system for transmitting a handover request to a base station of
Storage means for storing a history of handover, means for predicting a predicted cell with a high probability of handover as a handover destination cell based on the history of the storage means, and monitoring means for monitoring only the predicted cell A wireless communication system comprising a portable information terminal device.   The wireless communication system according to claim 1, wherein the storage unit stores at least the handover destination code, the handover time, and the number of handovers as the history of the handover.   3. The wireless communication according to claim 2, further comprising means for storing the handover completion time, the handover destination cell code, and the number of handovers as the history of the handover in the storage means when the handover is completed. system.   The means for predicting the prediction cell obtains the code and the number of times of the cell corresponding to the current time from the storage means, and predicts that the number of times of these codes exceeds a certain value as the handover destination cell. The wireless communication system according to claim 2 or claim 3, wherein   The said monitoring means determines the base station with the largest received power as a destination base station candidate from among the neighboring base stations when the predicted cell does not exist. A wireless communication system according to any one of the above.   6. The base station having the highest received power among the neighboring base stations is determined as a destination base station candidate when the communication state of the predicted cell deteriorates. The wireless communication system described. Based on the code of the neighboring cell included in the broadcast information of the serving cell, the base station with the highest received power is determined as a destination base station candidate from the neighboring base stations, and the base station of the serving cell is determined. Mobile information terminal device that transmits a handover request,
Storage means for storing a history of handover, means for predicting a predicted cell having a high probability of handover as a handover destination cell based on the history of the storage means, and monitoring means for monitoring only the predicted cell A portable information terminal device.   8. The portable information terminal device according to claim 7, wherein the storage unit stores at least the handover destination code, the handover time, and the number of handovers as the history of the handover.   9. The portable information according to claim 8, further comprising means for storing the handover completion time, the handover destination cell code, and the number of handovers as the history of the handover in the storage means when the handover is completed. Terminal device.   The means for predicting the prediction cell obtains the code and the number of times of the cell corresponding to the current time from the storage means, and predicts that the number of times of these codes exceeds a certain value as the handover destination cell. The portable information terminal device according to claim 8 or 9, characterized by the above.   The said monitoring means determines the base station with the largest received power as a destination base station candidate from among the surrounding base stations when the predicted cell does not exist. The portable information terminal device according to any one of the above.   12. The base station having the largest received power among the neighboring base stations when the communication state of the predicted cell deteriorates is determined as a destination base station candidate. The portable information terminal device described.   In the portable information terminal device, a base station with the largest received power is determined as a destination base station candidate from the surrounding base stations based on the codes of neighboring cells included in the broadcast information of the serving cell, and the serving cell A method for solving handover in a wireless communication system for transmitting a handover request to a base station of the mobile communication terminal device, the step of storing a history of handover in a storage means on the portable information terminal device side, and based on the history of the storage means A handover resolution method comprising: predicting a predicted cell with a high probability of handover as a handover destination cell; and monitoring only the predicted cell.   14. The handover resolution method according to claim 13, wherein the storage unit stores at least the handover destination code, the handover time, and the number of handovers as the handover history.   15. The handover resolution according to claim 14, further comprising the step of storing the handover completion time, the handover destination cell code, and the number of handovers as the handover history in the storage means when the handover is completed. Method.   The step of predicting the prediction cell obtains the code and the number of times of the cell corresponding to the current time from the storage means, and predicts that the number of times of these codes is a certain value or more as the handover destination cell. 16. The handover resolution method according to claim 14 or claim 15, wherein   The step of monitoring only the predicted cell is characterized in that, when the predicted cell does not exist, a base station having the highest received power is determined as a destination base station candidate from the neighboring base stations. The handover resolution method according to any one of claims 13 to 16.   18. The base station having the largest received power among the neighboring base stations is determined as a destination base station candidate when the communication state of the predicted cell deteriorates. The handover solution described. In the portable information terminal device, a base station with the largest received power is determined as a destination base station candidate from the surrounding base stations based on the codes of neighboring cells included in the broadcast information of the serving cell, and the serving cell A program for a handover solution of a wireless communication system that transmits a handover request to a base station of the wireless communication system, wherein the handover process is stored in a storage means in a computer, and the handover is performed based on the history of the storage means A program for executing a process of predicting a predicted cell having a high probability as a handover destination cell and a process of monitoring only the predicted cell.

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