JPH0677888A - Cell system radio telephone system - Google Patents

Abstract

PURPOSE:To reduce the power consumption by decreasing the frequency of the operation of a reception circuit at the time of measurement in the cell system radio telephone system in which a mobile station refers to a measurement object channel list for hand-over to measure a reception electric field strength. CONSTITUTION:For example, a base station A stores a measurement object channel list A for cells B, C, D, E, F, G being adjacent cells to a cell A. Upon the receipt of the list, a mobile station (a) measures the reception electric field strength of a frequency channel on the list and sends the measurement result to the base station A. The base station A discriminates to which cell hand-over is to be implemented based on the result of measurement and gives a command to the mobile station (a). The mobile station (a) selects a cell according to the command. Thus, since only a measurement object channel of cells adjacent to each cell is represented on the measurement object channel referenced by the mobile station, the reception electric field strength of only cells possibly being objects of succeeding hand-over has only to be measured and the frequency of the reception circuit operation at the measurement is reduced, then the power consumption is reduced and the battery service life is extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular radio telephone system.

[0002]

2. Description of the Related Art FIG. 6 is a diagram showing an example of cell arrangement in a mobile communication network managed by one telecommunications carrier in a conventional cell type wireless telephone system. Here, as a frequency channel for measuring the received electric field strength, one channel is assigned to one base station.

It is assumed that mobile station a is currently receiving service in cell A. Due to the movement of the mobile station a, the positional relationship with the base station A may change and the reception or transmission state may deteriorate. In such a case, the channel is switched to another cell with better communication (handover). There is a need to.

The mobile station measures the received electric field strengths of the current cell and peripheral cells in order to obtain a criterion for deciding whether or not to perform this handover. At this time, the mobile station measures by referring to the measurement target channel list that the mobile station itself has or that is sent from the base station. The measurement target channel list used by the mobile station a for measuring the received electric field strength is shown in FIG.
As shown in (1), channels for all cells in the mobile communication network are included. That is, one mobile communication network needs to manage one measurement target channel list, and all mobile stations in this network need to perform measurement based on this list.

Next, FIG. 7 shows a procedure until a handover is performed in this conventional cell type radio telephone system.
The mobile station a refers to the measurement target channel list received from the base station (or stored in the mobile station) and measures the received electric field strengths of all the frequency channels shown in this list. FIG. 8 shows an outline of the measurement timing. Here, it is assumed that the conditions for performing the measurement are determined as follows.・ Number of samples per channel: 3 ・ Measurement interval: 5 msec ・ Measurement cycle: 300 msec (measurement ends within 300 msec)

First, all the channels in the measurement target list are sequentially measured at intervals of 5 msec. This completes the measurement of the first sample. Similarly, the second sample and the third sample are continuously received, the measurement is terminated when the samples of all channels are taken, the average value is obtained for each channel, and the average value is calculated for each channel. Treated as received field strength.

Since the measurement target list shows the measurement target frequency channels of all cells in the mobile communication network X, in the case of the configuration of FIG. 6, the number of measurement channels is 18, that is, 18 × 3 = total. It is necessary to make 54 measurements. Therefore, it takes 265 mse to finish the measurement for 3 samples.
c takes. The samples thus obtained are averaged for each channel, and the average value is treated as the received electric field strength of each channel.

Next, some of the top ones having the highest received electric field strength are selected, and the neighboring cells which can be the target of the handover are identified for the first time. The selected handover candidate channel list is transmitted to the base station, the base station determines which cell in the list is suitable for handover, and notifies the mobile station. The mobile station receiving the notification switches to the channel of the designated cell and resumes the call.

[0009]

In this conventional cellular radio telephone system, for example, the received electric field strength from the base station L far away from the base station A is extremely low, and there is a possibility that it will be a target cell for handover. Absent. However, it is not known which cell can be a target cell for handover until all channels on the list, that is, all cells in one mobile communication network are measured and some upper cells are selected.

Therefore, since it is necessary to measure even a distant cell, which normally does not need to be measured, it takes a long time to perform the measurement. In addition, the frequency of operation of the receiving circuit and the like at the time of measurement increases, power consumption increases, and battery life shortens. Alternatively, there are drawbacks such as the need for a large-capacity battery for long-term operation.

An object of the present invention is to provide a cellular radio telephone system which reduces the frequency of operation of a receiving circuit during measurement and reduces power consumption.

[0012]

In order to achieve the above object, a cellular radio telephone system according to the present invention has a plurality of base stations in which a mobile station refers to a received electric field strength measurement target channel list in order to perform a handover. A cell type radio telephone system having a function of measuring a received electric field strength from a station, wherein the received electric field strength measurement target channel list shows only measurement target channels of at least cells adjacent to each cell, The mobile station refers to the list and measures the received electric field strength only with respect to the cell adjacent to the cell currently receiving the service (the radio communication link is established).

Also, in order to perform a handover, the mobile station is a cellular radio telephone system having a function of measuring received electric field strengths from a plurality of base stations by referring to a received electric field strength measurement target channel list. The station itself has a structure in which the measurement target channel list corresponding to each cell is owned in advance for all cells in the mobile communication network, and the mobile station receiving the service in the cell stores it in the mobile station. A list corresponding to the cell is selected from the measured measurement target channel list group, and the received electric field strength of the adjacent cell is measured with reference to this list.

[0014]

According to the present invention, the measurement target channel list referred to by the mobile station shows only the measurement target channels of the cells adjacent to the cell currently being served by the mobile station. It suffices to measure the received electric field strength only in the cells that are likely to be handed over, and the frequency of receiving circuit operation at the time of measurement is reduced, so that power consumption is reduced and battery life is extended.

[0015]

The present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing a relationship between cell arrangement and channels to be measured in a cellular radio telephone system according to Embodiment 1 of the present invention. Here, one channel is allocated to one base station as a channel to be measured for the received electric field level.

In FIG. 1, when the cell A is used as a reference, the adjacent cells are cells B, C, D, E, F and G. The telecommunications carrier creates a list of measurement target channel numbers corresponding to these adjacent cells in advance as a list A1 and stores it in a storage unit in the base station A.

Similarly, the cell B stores the list B1 in the cell C
In the list C1, all base stations own the measurement target channel list in that cell.

The feature of the present invention is that the content of the measurement target channel list is limited to only the channels of cells adjacent to the cell, and the list is owned by each base station. It is in.

Next, the operation until the handover is performed in this cell type radio telephone system will be described. FIG. 2 shows the procedure until the handover, and FIG. 3 shows the outline of the measurement timing. The mobile station a receives the measurement target channel list A1 from the base station A and stores it. Looking at this list, for example, the received electric field strength is measured from the channel number 2 of the cell B. The conditions for the measurement here are as follows.・ Number of samples per channel: 3 ・ Measurement interval: 5 msec ・ Measurement cycle: 300 msec (measurement ends within 300 msec)

In the system configuration of the present invention, the number of measurement channels is 6 because only the adjacent cells that can be candidates for handover are shown in the measurement target channel list. In this case, the measurement is performed 18 times in total, and the time required for the measurement is 85 msec.

Compared to the case where this measurement is performed under the same conditions under the conventional method, the number of measurement target channels is reduced to one-third, so that the number of measurement times and the measurement time are also one-third.
Has become.

As described above, according to the present invention, since the number of measurements can be reduced, the time required for measurement can be shortened. In addition, since the frequency of operation of the receiving circuit and the like during measurement is reduced, power consumption is reduced and battery life is extended.
Alternatively, a long-term operation does not require a large capacity battery.

(Embodiment 2) FIG. 4 is a diagram showing a relationship between a cell and a measurement target channel list according to Embodiment 2 of the present invention, and FIG. 5 is a diagram showing a handover procedure in this example. In this example, the mobile station owns the measurement target channel list corresponding to each cell for all cells in the mobile communication network X in advance. The mobile station a receiving the service in the cell A selects a list A1 corresponding to the cell A from the measurement target channel list group stored in the mobile station a, and refers to this list to select an adjacent cell. The received electric field strength of is measured. The measurement procedure is the same as in Example 1.

In this configuration, since the list corresponding to each cell stored in the mobile station may be referred to, not only the power consumption required for the measurement itself is reduced, but also the work of receiving the measurement target channel list from the base station becomes unnecessary. Therefore, the processing related to the handover is further simplified and the power consumption is reduced.

[0026]

As described above, according to the present invention, the measurement target channel list referred to by the mobile station shows only the measurement target channels of the cells adjacent to the cell currently being serviced by the mobile station. Therefore, it suffices to measure the received electric field strength only in the cell that is likely to be the target of the next handover, which reduces the frequency of receiving circuit operation during measurement, which reduces power consumption and battery life. The effect of extension is obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a flow from receiving a list to performing channel switching to an adjacent cell in the present invention.

FIG. 3 is a diagram showing a reception field strength measurement timing on a time axis during communication of the present invention.

FIG. 4 is a diagram showing a configuration when a mobile station holds a list in the present invention.

FIG. 5 is a diagram showing a flow until a channel is switched to an adjacent cell by referring to a list in a mobile station in the present invention.

FIG. 6 is a configuration diagram showing a conventional example.

FIG. 7 is a diagram showing a flow until a channel is switched to an adjacent cell in the conventional example.

FIG. 8 is a diagram showing a reception field strength measurement timing on a time axis during communication in the conventional example.

[Explanation of symbols]

A to S cell and base station number a Mobile station X Mobile communication network for wireless telephone composed of cells A to S A1, B1 Lists of cell numbers and measurement target channel numbers held by base stations A and B, respectively

Claims (2)

[Claims] 1. A cellular radiotelephone system having a function of measuring received electric field strengths from a plurality of base stations by referring to a received electric field strength measurement target channel list for performing handover. In the received electric field strength measurement target channel list, at least only the measurement target channels of the cells adjacent to each cell are shown, and the mobile station refers to the list and currently receives the service (wireless communication link). Cell radio telephone system characterized in that the received electric field strength is measured only with respect to a cell adjacent to the cell. 2. A cellular radiotelephone system having a function of measuring received electric field strengths from a plurality of base stations by referring to a received electric field strength measurement target channel list in order to perform a handover. The station itself has a structure in which the measurement target channel list corresponding to each cell is owned in advance for all cells in the mobile communication network, and the mobile station receiving the service in the cell stores it in the mobile station. A cell-based radio telephone system characterized in that a list corresponding to the cell is selected from the measurement target channel list group, and the received electric field strength of an adjacent cell is measured with reference to this list.