JP4648793B2 - Mobile communication system and mobile communication terminal - Google Patents

Description

  The present invention relates to mobile communication technology, and more particularly to standby control technology in a mobile communication system having a plurality of frequency channels.

  In recent years, mobile communication systems have become widespread, and next-generation mobile communication systems that enable high-speed multimedia communication have been developed. In order to accommodate a large number of users, it is common to construct a mobile communication system in which one communication carrier operates a plurality of frequency channels in the same region. As an example of a mobile communication system having a plurality of frequency channels, there is a W-CDMA (Wideband Code Division Multiple Access) system, and an OFCDM (Orthogonal Frequency and Code Division Multiplexing) system or the like is studied as a next generation communication system. ing.

  An example of a conventional mobile communication system is shown below. The communication system of the W-CDMA system is standardized by a standardization organization called 3GPP (3rd Generation Partnership Project). FIG. 5 is a system configuration diagram illustrating a configuration example of the W-CDMA system. As shown in FIG. 5, the W-CDMA system is a system that performs wireless communication between a plurality of base stations 51, 52, 53 arranged at certain intervals and a mobile communication terminal 54. Here, the mobile communication terminal 54 generally performs communication by selecting the optimum base station, for example, the base station 51, by measuring the quality of the received signal from each base station 51, 52, 53. Yes. While waiting, information from one base station having the strongest received radio wave, for example, base station 51, is received, but the quality of the received signal from this base station 51 is improved by moving mobile communication terminal 54. When the quality of the received signal from the neighboring base station, for example, the base station 52 is improved, the 3GPP standard “cell selection and cell in idle mode” as described in Non-Patent Document 1 Based on the determination criterion of “cell selection and reselection in idle mode”, the base station that receives the signal is changed to a base station with higher quality.

3rd Generation Partnership Project; “User Equipment (UE) procedures in idle mode and procedures for cell reselection in connected mode”, 3GPP TS25.304 V3.14.0, Section 5.2, (2004-03)

  However, in the standard described in Non-Patent Document 1, when selecting an optimal base station during standby, the base station to be switched is generally selected based on reception quality, and the mobile communication terminal 54 is selected. Information regarding the moving speed of the mobile station and the cell radii of the base stations 51, 52, 53 are not used. As a result, when the mobile communication terminal 54 moves at high speed during standby, there is a problem that the frequency of changing the standby base station increases.

  During standby, while the process of changing the base station for receiving information is being performed, the mobile communication terminal 54 cannot receive a call, so the probability of an incoming call failure increases, and the information is received. When the base station to be changed is changed, the current consumption of the mobile communication terminal 54 is increased, so that there is a problem that battery power is easily consumed and the standby time is shortened.

  Therefore, an object of the present invention is to perform standby control for selecting an optimal base station based on the moving speed of the mobile communication terminal and the cell radius of the base station, and when the mobile communication terminal moves at high speed, a stable standby state To achieve an improvement in the incoming call rate and a reduction in the current consumption of the mobile communication terminal. Another object of the present invention is to easily realize it by simply changing the control of the mobile communication terminal.

  According to an aspect of the present invention, in a mobile communication system having a plurality of base stations and mobile communication terminals that can communicate with each of the base stations, the mobile communication terminal receives a signal received from each of the base stations. A base station information detecting means for detecting base station information including a level value; and a moving speed detecting means for detecting its own moving speed, and based on the detected base station information and the moving speed, Provided is a mobile communication system characterized by performing standby control for selecting a station.

  In the above system, standby control is performed such that an optimum base station is preferentially selected according to the moving speed of the mobile communication terminal and the cell radius of each base station.

  Further, a standby control parameter holding unit for holding a standby control parameter for switching to an optimal base station in a standby state is provided, and the standby control parameter, the detected base station information, and the moving speed are included. Based on this, it is preferable to perform standby control for selecting a base station. Thereby, a certain reference | standard can be set and a base station can be selected more accurately.

  According to another aspect of the present invention, base station information detection is a mobile communication terminal capable of communicating with each of a plurality of base stations, and detects base station information including a received signal level value from each of the base stations. Means, a moving speed detecting means for detecting its own moving speed, and a means for holding a standby control parameter, and based on the standby control parameter, the detected base station information and the moving speed, There is provided a mobile communication terminal characterized by performing standby control for selecting a station.

  According to another aspect of the present invention, there is provided a communication method in a mobile communication system having a plurality of base stations and a mobile communication terminal capable of communicating with each of the base stations, and a received signal from each of the base stations Detecting base station information including a level value; and detecting a moving speed of the mobile communication terminal; and selecting a base station based on the detected base station information and the moving speed And a step of performing standby control.

  According to the present invention, the mobile communication terminal is placed on standby by performing standby control that preferentially selects an optimal base station according to the moving speed of the mobile communication terminal and the size of the cell radius for each base station. If it is in the middle, it is possible to reduce the probability of failure of incoming calls, and it is possible to prevent an increase in current consumption by reducing the frequency of changing the base station that receives the information.

  A mobile communication system and a mobile communication terminal according to an embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a cell configuration example of a mobile communication system according to the present embodiment. As shown in FIG. 1, in the mobile communication system according to the present embodiment, base stations 11, 12,..., 15 having cells 11z, 12z,. Arranged in a state. Here, the cell radius is determined by various factors such as the transmission power of the base station and the frequency to be used. For example, the cell radius is larger and the frequency to be used is lower when the base station transmission power is larger. However, since the propagation loss is reduced, the cell radius is increased. In the example shown in FIG. 1, the cells 11z, 12z, 13z, and 14z are cells having a small cell radius, and the cell 15z is a cell having a large cell radius.

  The mobile communication terminal performs communication while moving in the overlapping cells. For example, as shown by arrows in FIG. 1, the mobile communication terminal passes from the position 16 of the communication range of the cells 11z and 15z, that is, the base stations 11 and 15, via the communication range of the cells 14z and 15z, that is, the base stations 14 and 15. It is assumed that the cells 13z and 15z are moving toward the position 17 in the communication range of the base stations 13 and 15.

  The mobile communication terminal is provided with a plurality of reception quality offset values. Here, the reception quality offset value is a standby control parameter used for standby control, and is set in advance as a value corresponding to the moving speed of the mobile communication terminal and the cell radius of each base station, The present invention is applied to select an optimal base station according to the magnitude of the moving speed and change the base station to wait for.

  For example, when a waiting mobile communication terminal moves at a high speed, a base station with a larger cell radius has a larger reception quality offset value, and a base station with a larger cell radius actually receives a received signal received by the mobile communication terminal. By using the reception quality offset value to update the reception signal with better quality than the quality, the base station with a large cell radius is selected with priority, the base station to be waited on is changed, and the mobile station moves at high speed. Control is performed to reduce the frequency of changing the base station that receives information from time to time.

  FIG. 2 is a functional block diagram showing a configuration example of a mobile communication terminal according to the present embodiment, and is a diagram showing an example of a terminal applied to the mobile communication system as shown in FIG. As shown in FIG. 2, the mobile communication terminal 20 includes at least a communication unit 21 that transmits and receives signals to and from the base station, a signal processing unit 22 that processes transmission and reception signals to and from the base station, and a mobile communication terminal. A speed detection unit 23 that detects 20 moving speeds and a control unit 24 that controls each unit are provided.

  The control unit 24 performs various processes necessary for mobile communication of the mobile communication terminal 20, including operations related to standby cell selection control for changing a standby base station, and at least an optimal base in a standby state A standby control unit 24a that controls operations related to standby control for switching to a station, and a base station information detection unit 24b that detects information of each base station. The base station information detection unit 24b performs base information on information specifying each base station (base stations 11, 12,..., 15 in the case of FIG. 1) and base station information including a received signal quality value from each base station. Detection is performed for each station, and in some cases, detection is performed including information for estimating the cell radius of each base station.

  Next, the operation of the mobile communication system according to this embodiment will be described using the configuration shown in FIGS. 1 and 2 as an example. FIG. 3 is a process flow diagram of the mobile communication system according to the present embodiment. Here, in the present embodiment, first, the mobile communication terminal 20 is present at the position 16 in FIG. 1 and is waiting from the base station 11, and is directed in the direction of the arrow in FIG. And move.

  In the example shown in FIG. 3, first, the mobile communication terminal 20 measures the reception quality of signals received from the standby base station 11 and the surrounding base stations 12, 13, 14, and 15 in the communication unit 21. Then, the base station information detection unit 24b detects the base station information together with the information specifying each base station (step S1). Furthermore, the mobile communication terminal 20 measures the moving speed V of the mobile communication terminal 20 in the speed detecting unit 23 (step S2).

  Next, the mobile communication terminal 20 determines the base station information including the reception quality of each base station 11, 12,..., 15 measured and detected in step S 1 based on information predetermined as the entire mobile communication system to be applied. Base station (base station 15 in the case of FIG. 1) group, base station having a small cell radius (base stations 11 to 14 in FIG. 1) group (Step S3).

  For example, in the case of a mobile communication system using 2 GHz and 800 MHz, generally, a base station using 800 MHz has a smaller propagation loss than a base station using 2 GHz, so the cell radius is increased. be able to. Therefore, as the predetermined information on each base station of the entire mobile communication system, 2 GHz is used for a base station group having a large cell radius from a base station using 800 MHz based on information on the frequency used by each base station. The base stations can be grouped into base station groups having a small cell radius.

  Next, the mobile communication terminal 20 determines whether or not the moving speed V is equal to or higher than a moving speed threshold value Vth1 held as a predetermined value (step S4). When the moving speed V of the mobile communication terminal 20 is equal to or higher than the moving speed threshold Vth1 (YES in step S4), base stations belonging to a base station group having a large cell radius so that switching of base stations for communication or standby does not occur frequently. (In the case of FIG. 1, the reception is held as a predetermined value for the reception quality of the base station belonging to the base station group having a large cell radius so that the base station 15 can be selected preferentially. The quality offset value Loff1 is applied to update the reception quality of the base station (step S5).

  Next, based on the base station information including the reception quality of the base station updated in step S5, the mobile communication terminal 20 has a base station (mobile communication terminal 20 having a better quality than the currently waiting base station 11). If the base station 15) having a large cell radius exists, the base station that is waiting for the base station 11 (for example, the base station 15) having good reception quality of the standby information from the base station 11 is selected. The operation related to standby control to be changed to (step S6).

  In step S4, when the moving speed V of the mobile communication terminal 20 is not equal to or higher than the moving speed threshold value Vth1 (NO in step S4), the process proceeds to step S6 through step S5 and the same processing as described above is performed.

  As described above, in this communication method, reception is performed based on the reception quality offset value Loff1 and the moving speed threshold value Vth1 that are held as predetermined values, the base station information detected by the mobile communication terminal 20, and the moving speed V. It is possible to preferentially select the optimum base station having the best quality as the standby base station.

  Next, a second embodiment of the mobile communication system according to the present invention will be described with reference to FIG. 4 taking the configuration shown in FIGS. 1 and 2 as an example. FIG. 4 is a processing flowchart showing the operation of the mobile communication system according to the present embodiment. Here, in the present embodiment, first, the mobile communication terminal 20 is present at the position 16 in FIG. 1 and is waiting from the base station 11, and is directed in the direction of the arrow in FIG. And move.

  In the mobile communication system according to the first embodiment shown in the processing flow diagram of FIG. 3, when the moving speed V of the mobile communication terminal 20 is equal to or higher than the moving speed threshold Vth1, the reception quality of the base station having a large cell radius is reduced. The measurement quality offset value Loff1 was applied. In the case of the mobile communication system according to the first embodiment, even if the mobile communication terminal 20 that has moved at high speed is stopped, the mobile communication terminal 20 is waiting from a base station having a large cell radius (in the case of FIG. 1, the base station 15). Therefore, there is a possibility that the mobile communication terminal 20 that has a possibility of high-speed movement tends to stand by from a base station with a large cell radius.

  Therefore, in the present embodiment, the first moving speed threshold value Vth1, the second moving speed threshold value Vth2, the first received quality offset value Loff1, the second moving speed threshold value and the received quality offset value used as the standby control parameters, respectively. When two types of reception quality offset values Loff2 are prepared and the moving speed V of the mobile communication terminal 20 is faster than the first moving speed threshold Vth1, the first moving speed that can preferentially select a base station having a large cell radius. The threshold value Vth1 is applied. On the other hand, when the moving speed V is as low as the second moving speed threshold value Vth2 or less, the second reception quality offset value Loff2 that can preferentially select a base station having a small cell radius can be applied. An example of avoiding biasing to standby from a specific base station will be described.

  Specifically, first, in step S11 of FIG. 4, processing of each step from step S1 to S5 of FIG. 3 (that is, processing in the range of A1 surrounded by a broken line in the flowchart of FIG. 3) is performed. When the description is repeated, the mobile communication terminal 20 measures the reception quality of the signals received from the standby base station 11 and the surrounding base stations 12, 13, 14, 15 in the communication unit 21, and each base station And the base station information detection unit 24b detect the base station information as information on the base station (step S1). Furthermore, the mobile communication terminal 20 measures the moving speed V of the mobile communication terminal 20 in the speed detecting unit 23 (step S2).

  Next, the mobile communication terminal 20 determines the base station information including the reception quality of each base station 11, 12,..., 15 measured and detected in step S 1 based on information predetermined as the entire mobile communication system to be applied. From the base station having a large cell radius (base station 15 in the case of FIG. 1), and a base station having a small cell radius (base stations 11 to 14 in FIG. 1). Grouping is performed (step S3). For example, in the case of a mobile communication system using 2 GHz and 800 MHz, generally, a base station using 800 MHz has a smaller propagation loss than a base station using 2 GHz, so the cell radius is increased. be able to. Accordingly, as predetermined information about each base station of the entire mobile communication system, based on information on the frequency used by each base station, base stations using 800 MHz are grouped into a base station group having a large cell radius, and 2 GHz. The base stations using can be grouped into base station groups having a small cell radius.

  Next, the mobile communication terminal 20 determines whether or not the movement speed V of the mobile communication terminal 20 is equal to or higher than a movement speed threshold Vth1 held as a predetermined value (step S4). When the moving speed V of the mobile communication terminal 20 is equal to or higher than the moving speed threshold Vth1 (YES in step S4), a base belonging to a base station group having a large cell radius so as not to frequently switch base stations for communication or standby. In order to preferentially select a station (base station 15 in the case of FIG. 1), the reception quality of a base station belonging to a base station group having a large cell radius is held as a predetermined value. The reception quality offset value Loff1 is applied to update the reception quality of the base station (step S5). In step S4, when the moving speed V of the mobile communication terminal 20 is not equal to or higher than the moving speed threshold value Vth1 (NO in step S4), the process proceeds to step S6 through step S5 and the same processing as described above is performed.

  Further, unlike the above-described first embodiment of FIG. 3, the mobile communication terminal 20 determines whether or not the moving speed V is equal to or lower than a second moving speed threshold Vth2 held as a predetermined value ( Step S12). When the moving speed V of the mobile communication terminal 20 is less than or equal to the second moving speed threshold value Vth2 (YES in step S12), base stations belonging to a base station group having a small cell radius (see FIG. In the case of 1, in order to be able to preferentially select the base stations 11 to 14), the reception quality of the base stations belonging to the base station group having a small cell radius is held as a predetermined value. 2 The reception quality offset value Loff2 is applied to update the reception quality of the base station (step S13).

  Next, based on the base station information including the reception quality of the base station updated in step S5 or step S13, the mobile communication terminal 20 has a higher quality base station (mobile) than the currently waiting base station 11. When the communication terminal 20 moves at a high speed, a base station 15 having a large cell radius, when moving at a low speed, a base station 14 having a small cell radius, and then a base station 13) is present, the base station that is on standby Is changed to a base station (for example, the base station 15, the base station 14, and then the base station 13) with good reception quality of the standby information from the base station 11 (step S14).

  As described above, the first reception quality offset value Loff1, the second reception quality offset value Loff2, the first movement speed threshold value Vth1, the second movement speed threshold value Vth2, and the mobile communication terminal 20 detected as predetermined values are detected. If the moving speed V detected by the mobile communication terminal 20 is equal to or higher than the first moving speed threshold value Vth1 received from the base station 11 based on the base station information and the moving speed V, the reception for each detected base station is received. The value updated by adding the first reception quality offset value Loff1 received from the base station 11 to the signal quality value is used as the updated reception signal quality of each base station, and the moving speed V detected by the mobile communication terminal 20 is the base station. 11, the second received quality offset value received from the base station 11 is added to the detected received signal quality value for each base station. The updated value by adding the off2, the updated received signal quality of each base station, the most updated received signal quality is good base station, so that it is determined that the optimum base station to standby.

  Thus, in this communication method, when moving at high speed, a base station having a large cell radius (base station 15 in the case of FIG. 1) is preferentially selected, and when moving at low speed, the cell radius is small. By preferentially selecting the base station (in the case of FIG. 1, the base station 14 and then the base station 13), it is possible to reduce the number of times of changing the standby base station when the mobile station is waiting during high-speed movement. It becomes. In addition, the load on the mobile communication terminal 20 and each base station is reduced to ensure the stability of communication, and when shifting to low speed movement, the base station having a large cell radius waits from a base station having a small cell radius. By switching, stable operation as a mobile communication system can be performed without being biased toward a specific base station.

  Various methods are conceivable as means for measuring the moving speed V of the mobile communication terminal. For example, a method of detecting the moving speed V using an acceleration sensor, a method of detecting the moving speed V from the frequency / phase information of the received radio signal, a method of obtaining the moving speed V from information of other speed detecting means such as GPS, There are a method of estimating the moving speed V based on the frequency of handover during communication and the frequency of base station change during standby, a method of acquiring the moving speed V from an external device such as a speedometer of an automobile equipped with a mobile communication terminal, and the like.

  In addition, the definition of standby includes not only idle mode defined in 3GPP but also a communication state using a common channel such as CELL_PCH, CELL_FACH, URA_PCH.

  In addition, the definition of the base station in the present embodiment includes a base station, a network controller connected to the base station, and a backbone network.

It is a block diagram which shows an example of the cell structure of the mobile communication system by the 1st Embodiment of this invention. It is a block diagram which shows an example of the mobile communication terminal by this Embodiment. It is a processing flow figure which shows the 1st Example of the mobile communication system by this Embodiment. It is a processing flowchart which shows operation | movement of the mobile communication system by the 2nd Embodiment of this invention. It is a system configuration diagram showing an example of a configuration of a W-CDMA system.

Explanation of symbols

11, 12, 13, 14, 15 ... base station, 11z, 12z, 13z, 14z ... cell with small cell radius, 15z ... cell with large cell radius, 16, 17 ... position of mobile communication terminal, 20 ... mobile communication terminal , 21 ... communication unit, 22 ... signal processing unit, 23 ... speed detection unit, 24 ... control unit, 24a ... standby control unit, 24b ... base station information detection unit, 51, 52 ... base station (2 GHz), 53 ... base Station (800 MHz), 54... Mobile communication terminal.

Claims (10)

In a mobile communication system having a plurality of base stations and a mobile communication terminal capable of communicating with each of the base stations,
The mobile communication terminal is
Base station information detecting means for detecting base station information including a received signal level value from each of the base stations and a cell radius of the base station;
A moving speed detecting means for detecting the moving speed of the self,
Based on the detected base station information and the moving speed, it has row control waiting selects a base station,
When the detected moving speed is equal to or greater than a predetermined first moving speed threshold, the base station having a cell radius equal to or greater than a predetermined first threshold is set to the first received signal level value for each detected base station. The value updated by adding the offset value is the updated received signal quality value of each base station,
When the detected moving speed is equal to or smaller than a predetermined second moving speed threshold, the second base station having a cell radius equal to or smaller than a predetermined second threshold is set to a second received signal level value for each detected base station. The value updated by adding the offset value is the updated received signal quality value of each base station,
A mobile communication system, wherein a base station suitable for standby is selected in consideration of an updated received signal quality value . A standby control parameter holding unit for holding a standby control parameter for switching to an optimal base station in a standby state;
The mobile communication system according to claim 1, wherein standby control for selecting a base station is performed based on the standby control parameter, the detected base station information, and the moving speed.   The mobile communication system according to claim 2, wherein the standby control parameter is an offset value for a received signal quality value included in the base station information for each base station detected by the mobile communication terminal.   The mobile communication system according to claim 3, wherein a plurality of the offset values are held in the standby control parameter holding unit.   The mobile communication system according to claim 4, wherein a plurality of offset values based on a cell radius of the base station are used. A mobile communication terminal capable of communicating with each of a plurality of base stations,
Base station information detecting means for detecting base station information including a received signal level value from each of the base stations and a cell radius of the base station ;
A moving speed detecting means for detecting the moving speed of the self
Means for holding standby control parameters ;
Comprising
And the waiting control parameter, on the basis of the the detected said base station information said moving speed, have row control waiting selects a base station,
When the detected moving speed is equal to or greater than a predetermined first moving speed threshold, the base station having a cell radius equal to or greater than a predetermined first threshold is set to the first received signal level value for each detected base station. The value updated by adding the offset value is the updated received signal quality value of each base station,
When the detected moving speed is equal to or smaller than a predetermined second moving speed threshold, the second base station having a cell radius equal to or smaller than a predetermined second threshold is set to a second received signal level value for each detected base station. The value updated by adding the offset value is the updated received signal quality value of each base station,
A mobile communication terminal characterized by determining an optimum base station for standby in consideration of an updated received signal quality value . The waiting control parameter the mobile communication terminal is held, according to claim 6, characterized in that the offset value for the received signal quality value, wherein the mobile communication terminal is included in the base station information for each base station detected Mobile communication terminals. The mobile communication terminal according to claim 7 , wherein the means for holding the standby control parameter holds a plurality of offset values. The mobile communication terminal according to claim 8 , wherein a plurality of offset values based on a cell radius of the base station are used. A communication method in a mobile communication system having a plurality of base stations and a mobile communication terminal capable of communicating with each of the base stations,
Detecting base station information including a received signal level value from each of the base stations and a cell radius of the base station;
Detecting a moving speed of the mobile communication terminal;
Comprising
Based on the detected base station information and the moving speed, it has a standby control step performs standby control selects a base station,
In the standby control step,
When the detected moving speed is equal to or greater than a predetermined first moving speed threshold, the base station having a cell radius equal to or greater than a predetermined first threshold is set to the first received signal level value for each detected base station. The value updated by adding the offset value is the updated received signal quality value of each base station,
When the detected moving speed is equal to or smaller than a predetermined second moving speed threshold, the second base station having a cell radius equal to or smaller than a predetermined second threshold is set to a second received signal level value for each detected base station. The value updated by adding the offset value is the updated received signal quality value of each base station,
A communication method characterized by determining an optimum base station for standby in consideration of an updated received signal quality value .

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