JP2006135520A - Selecting method for radio base station device and wireless access network system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio base station device selecting method capable of preventing power consumption of a mobile terminal and lowering of a system capacity, and to provide a wireless access network system. <P>SOLUTION: Each radio base station generates network information including the transmission power value of a pilot channel, and always transmits the network information and the pilot channel into an area which each device manages. The mobile terminal measures a desired wave to interference wave ratio and the received field strength of the pilot channel transmitted from each radio base station device respectively, extracts and regenerates information on the transmission power value of the pilot channel from the network information, and computes a distance from the viewpoint of an electric wave of each radio base station device from a measurement of the received field strength and the transmission power value, respectively. A radio base station whose distance from the viewpoint of an electric wave is the shortest, and measurement of the desired wave to interference wave ratio is the most satisfactory is selected as the device of an awaiting object. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mobile communication system, and more particularly to a radio access network system which is an access system for connecting to a network from a mobile terminal owned by a user.

  In a mobile communication system, an access system for connecting to a network from a mobile terminal owned by a user is called a radio access network system. In general, a ready state in which a mobile terminal can make a call connection to a network via a radio base station apparatus is called a “standby state”. In order for the mobile terminal to be in a standby state, it is necessary to acquire network information including information for identifying the radio base station device, which is broadcast from each radio base station device. At that time, the mobile terminal measures the radio quality of each known pilot CH (channel) transmitted from a plurality of radio base station apparatuses, and obtains radio quality equal to or higher than a preset threshold value. By selecting, the accuracy of network information to be acquired is ensured.

  A mobile terminal that has selected a radio base station device registers its location in a radio network controller (RNC: Radio Network Controller) through the radio base station device (hereinafter referred to as a radio base station device to be awaited) and shifts to a standby state. To do.

  Conventionally, as the radio quality used for the selection of the radio base station apparatus, the value of the received electric field strength of the pilot CH and the desired wave-to-interference wave ratio is used. In particular, in a W-CDMA mobile communication system, the desired wave-to-interference wave Ratio is mainly used.

Various methods are considered for selection of a radio base station apparatus by a mobile terminal. For example, in a mobile communication system of a small zone system (cellular system), transmission power and actual transmission power of a plurality of radio base station apparatuses in a mobile terminal Patent Document 1 describes that each propagation loss is calculated from the difference in received power received at the same time, and a radio base station apparatus with the smallest propagation loss is selected and communicated.
Japanese Patent Laid-Open No. 2-126738

  In a W-CDMA mobile communication system, since a plurality of mobile terminals perform radio communication using the same frequency band, even when receiving radio waves from nearby radio base station apparatuses, radio performed by other mobile terminals is performed. The ratio of desired wave to interference wave may deteriorate due to communication.

  Therefore, when a standby radio base station apparatus is selected based only on the desired wave-to-interference wave ratio value, call connection may be attempted to a remote radio base station apparatus, thereby increasing the power consumption of the mobile terminal. . In addition, since the transmission power from the radio base station apparatus having a restriction on the total transmission power to the mobile terminal increases, the system capacity decreases.

  The present invention has been made to solve the above-described problems of the prior art, and a radio base station apparatus selection method and a radio access network system capable of preventing a reduction in power consumption and system capacity of a mobile terminal. The purpose is to provide.

  In order to achieve the above object, in the present invention, a radio base station apparatus generates network information including a transmission power value of a pilot channel, and the network information and the pilot channel are within an area managed by each radio base station apparatus. Always send.

On the other hand, the mobile terminal measures the received electric field strength and the desired wave to interference wave ratio of the pilot channel transmitted from the radio base station device, respectively.
Extract and reproduce pilot channel transmission power value information from the network information transmitted from the radio base station device,
Calculate the radio wave distance for each radio base station device from the received electric field strength measurement result and the transmission power value,
The radio base station apparatus with the shortest radio distance and the best measurement result of the desired wave-to-interference wave ratio is selected as the radio base station apparatus for entering the standby state.

  In the present invention, the mobile terminal selects the radio base station apparatus with the shortest radio wave distance and the best desired wave-to-interference wave ratio as the standby radio base station apparatus at the mobile terminal. An increase in power is suppressed. Also, transmission power from the radio base station apparatus to the mobile terminal is suppressed.

  According to the present invention, an increase in power consumption of a mobile terminal is suppressed. In addition, since transmission power from the radio base station apparatus to the mobile terminal is suppressed, a reduction in system capacity is prevented.

  Next, the present invention will be described with reference to the drawings.

  In the present invention, when a mobile terminal selects a radio base station apparatus to be awaited, the movement at the time of call connection is considered by considering not only the desired wave-to-interference wave ratio but also the radio distance from the radio base station apparatus. The transmission power to the terminal is suppressed to prevent the system capacity from decreasing.

  FIG. 1 is a block diagram showing a configuration example of a radio access network system.

  As shown in FIG. 1, the radio access network system includes a radio base station device (Node-B) 20 capable of communicating with a plurality of mobile terminals (UE) 10 via a radio channel, and a plurality of radio base station devices. 20 is connected to a radio network controller (RNC: Radio Network Controller) 30 that manages location information of each mobile terminal.

  As shown in FIG. 2, the mobile terminal 10 includes a control device 11 that selects a radio base station device for call connection control and standby during a call, and a transmission / reception device 12 that performs radio communication with the radio base station device 20. The storage device 13 stores information used by the control device 11, processing results, and the like.

  The radio base station apparatus 20 performs transmission / reception data demultiplexing / multiplexing processing for each mobile terminal 10 and performs radio communication with the mobile terminal 10 and the control apparatus 21 that generates network information including the transmission power value of the pilot CH. For example, a communication control device 23 for communicating with the wireless network control device 30.

  The radio network controller 30 also manages the location information of each mobile terminal 10 and performs a call connection, a handover process, etc. for each mobile terminal 10, a switch unit 32 that switches data flows, and a plurality of switches It is the structure which has the communication control apparatus 33 for communicating with the radio base station apparatus 20.

  Each control device of the mobile terminal 10, the radio base station device 20, and the radio network control device 30 includes, for example, a DSP, a CPU, a memory such as a RAM and a ROM, a recording medium on which a program is recorded, and other LSIs (for example, a bus). Controller, I / O controller, etc.). Each processing of the wireless network control device 30 and the mobile terminal 10 described below is realized by, for example, an LSI constituting the control device or a CPU or DSP that executes processing according to a program recorded on a recording medium.

  Next, the operation of the radio access network system of the present invention will be described with reference to the drawings.

  In the radio base station apparatus 20 of the present invention, the control apparatus 21 generates network information including the transmission power value of the pilot CH as described above, and transmits the network information to each mobile terminal 10 via the radio line, for example, by the transmission / reception apparatus 22. . The radio base station apparatus 20 always transmits the network information and the pilot CH within the area managed by the own apparatus.

  On the other hand, the mobile terminal 10 of the present invention measures the received electric field strength and the desired wave to interference wave ratio of the pilot CH transmitted from the radio base station apparatus 20. Also, information on the transmission power value of the pilot CH is extracted from the network information transmitted from the radio base station apparatus 20, and the information is demodulated and reproduced. Then, the radio wave distance L for each radio base station apparatus 20 is calculated from the reception field strength measurement result R and the transmission power value P, and the desired wave to interference wave ratio measurement result E and the radio wave distance L are respectively calculated. The radio base station device to be awaited is determined in consideration.

  Hereinafter, the operation of the mobile terminal 10 will be described with reference to FIG.

  FIG. 3 is a flowchart showing the processing procedure of the mobile terminal of the present invention. In addition, the process of the mobile terminal 10 shown below shall be performed by the control apparatus 11 with which the mobile terminal 10 is provided.

  As shown in FIG. 3, the control device 11 first measures the received electric field strength and the desired wave-to-interference wave ratio of the pilot CH transmitted from the radio base station device 20. In addition, the transmission power value information of the pilot CH is extracted from the network information transmitted from the radio base station apparatus 20 and reproduced (step S1).

  Next, the control device 11 stores the measurement result R of the received electric field strength of the pilot CH, the measurement result E of the desired wave-to-interference wave ratio, and the transmission power value P of the pilot CH acquired from the network information in the storage device 13, respectively. (Step S2). These pieces of information may be stored in the storage device 13 in a table format, for example, in association with each radio base station device 20 that has received the pilot CH.

  Subsequently, the control device 11 reads the reception field strength measurement result R and the transmission power value P of the pilot CH from the storage device 13 for each radio base station device 20, and each radio wave distance L (L = R−). P) is calculated (step S3), and the calculation result is stored in the storage device 13.

  Next, the control device 11 reads the measurement result E of the desired wave-to-interference wave ratio and the radio wave distance L from the storage device 13, respectively, and generates a graph (FIG. 4) showing the relationship between them (step S4). The graph shown in FIG. 4 corresponds to the values of L and E obtained for each radio base station apparatus 20 with the x axis as the radio wave distance L and the y axis as the measurement result E of the desired wave to interference wave ratio. This is an example in which identification information and the like (の in the figure) of each radio base station apparatus 20 are plotted on the coordinates.

  Finally, based on the graph shown in FIG. 4, the control device 11 has the smallest value of L (x-axis) (the shortest radio wave distance L) and the best value of E (y-axis). Is selected as a standby target radio base station apparatus (step S5).

  In this process, in order to suppress a known ping-pong phenomenon that occurs due to fluctuations in the received electric field strength, the process is started after a predetermined time has elapsed since the value of the received electric field intensity exceeds a predetermined threshold value. It is desirable to set a so-called Time to Trigger.

  According to the radio access network system of the present invention, in order to select the radio base station device 20 having the shortest radio wave distance L and the best desired wave to interference wave ratio E as the standby radio base station device, An increase in power consumption of the mobile terminal 10 is suppressed. Moreover, since transmission power from the radio base station apparatus 20 to the mobile terminal 10 is suppressed, the system capacity increases.

  Furthermore, in the present invention, since the mobile terminal 10 autonomously selects the radio base station device 20, it is not necessary to change the radio network control device 30 or the like.

  In the above description, an example using the radio wave distance L calculated by the difference between the transmission power value of the pilot CH transmitted from the radio base station apparatus 20 and the received electric field strength is shown. The propagation distance to each radio base station apparatus 20 may be calculated and used instead of the radio wave distance L. As a calculation method of the propagation distance, for example, a GPS (Global Positioning Service) receiving device is mounted on each radio base station device 20, and a predetermined signal (for example, a known preamble signal) whose transmission timing is matched from each radio base station device 20 is used. ). The mobile terminal calculates a propagation distance to each radio base station apparatus 20 by detecting a difference in reception timing of the predetermined signal received from each radio base station apparatus 20. The same effect as described above can be obtained even when a radio base station apparatus that is symmetric with respect to standby is selected using the measurement result E of the propagation distance and desired wave-to-interference wave ratio for each radio base station apparatus 20 obtained in this way. It is done.

It is a block diagram which shows the example of 1 structure of a radio | wireless access network system. It is a block diagram which shows the example of 1 structure of the mobile terminal shown in FIG. It is a flowchart which shows the process sequence of the mobile terminal of this invention. FIG. 4 is a graph used in selection processing of a radio base station apparatus by the mobile terminal shown in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mobile terminal 11, 21, 31 Control apparatus 12, 22 Transmission / reception apparatus 13 Storage apparatus 20 Wireless base station apparatus 23, 33 Communication control apparatus 30 Wireless network control apparatus 32 Switch part

Claims (7)

A method of selecting a radio base station apparatus for selecting a radio base station apparatus for entering a standby state by a mobile terminal,
Generate network information including a transmission power value of a pilot channel in the radio base station apparatus, and constantly transmit the network information and the pilot channel in an area managed by each radio base station apparatus,
The mobile terminal that has received the network information and the pilot channel measures the received electric field strength and the desired wave to interference wave ratio of the pilot channel transmitted from the radio base station device, respectively.
Extracting and reproducing the information of the transmission power value of the pilot channel from the network information transmitted from the radio base station device,
Calculate the radio distance for each radio base station apparatus from the measurement result of the received electric field strength and the transmission power value,
Method of selecting a radio base station apparatus that selects the radio base station apparatus that has the closest radio wave distance and the best measurement result of the desired wave to interference wave ratio as the radio base station apparatus to enter the standby state . When the radio wave distance is L, the received electric field strength of the pilot channel is R, and the transmission power value of the pilot channel is P,
The radio wave distance L is
L = RP
The method of selecting a radio base station apparatus according to claim 1, obtained by: A wireless base station device that generates network information including a transmission power value of a pilot channel and constantly transmits the network information and the pilot channel in an area managed by the device;
The received electric field strength and desired wave-to-interference wave ratio of the pilot channel transmitted from the radio base station apparatus are respectively measured, and the information on the transmission power value of the pilot channel is obtained from the network information transmitted from the radio base station apparatus. Extracting and reproducing, calculating the radio wave distance for each radio base station apparatus from the measurement result of the received electric field strength and the transmission power value, respectively, the radio wave distance is the closest, and the desired wave to interference wave ratio A mobile terminal that selects a radio base station apparatus for waiting for the radio base station apparatus with the best measurement result,
A wireless access network system. When the radio wave distance is L, the received electric field strength of the pilot channel is R, and the transmission power value of the pilot channel is P,
The radio wave distance L is
L = RP
The wireless access network system according to claim 3, which is obtained by: A control device for generating network information including the transmission power value of the pilot channel;
A transmitting / receiving device that constantly transmits the network information and the pilot channel in an area managed by the device;
A radio base station apparatus. Measure the received field strength and desired wave-to-interference ratio of the pilot channel transmitted from the radio base station apparatus, and extract the information of the transmission power value of the pilot channel from the network information transmitted from the radio base station apparatus And calculating the radio wave distance for each radio base station apparatus from the measurement result of the received electric field strength and the transmission power value, and the radio wave distance is the closest and the desired wave to interference wave ratio is A control device that selects a radio base station device with the best measurement result as a radio base station device to enter a standby state;
A storage device that temporarily holds a measurement result of the received electric field strength and a desired wave-to-interference wave ratio of the pilot channel, a transmission power value of the pilot channel, and a radio distance for each radio base station device;
A mobile terminal. When the radio wave distance is L, the received electric field strength of the pilot channel is R, and the transmission power value of the pilot channel is P,
The controller is
The radio wave distance L is
L = RP
The mobile terminal according to claim 6, which is obtained by:

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