JP3254649B2 - Wireless communication control method for mobile communication - Google Patents

Abstract

PURPOSE:To enable the use of both frequency zone A (800MHz) and a frequency zone B (1.5GHz) and to prevent the deviation of traffic to the frequency zone A by judging the use propriety of a line by correcting the reception level informed from a mobile station when a base station judges the use propriety. CONSTITUTION:A mobile station 15 notifies the monitoring channel number of the surrounding radio zone from the base station 2 of a radio zone 2 to the mobile station 15 for the radio zone 2 of a radio zone number 2. At the time, because the station 15 is in speech in a frequency band A, each monitoring channel number N1 and N2 of the surrounding zone numbers 1 and 3 of the band A is notified next, a correction level alpha is notified, and subsequently, each monitoring channel number N'1 to N'3 of the surrounding zone number 1' to 3' of a frequency band B is notified. The station 15 receiving the notification measures the reception level of the monitoring channel from the surrounding radio zone. The station 15 further adds alpha to the reception levels E'1 to E'3 of the monitoring channels N'1 to N'3 of and reports the matter to a base station 9. The station 9 deduces a radio zone 1' from the N'1, performs inquiries to the base station 8' and switched to the calling channel of the mobile station 15 by the reply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention covers a service area with a plurality of radio zones, provides base stations in each radio zone, and communicates the reception level of a monitoring channel of a peripheral radio zone notified from the base station. At the mobile station,
The measured reception level information is reported to the base station, and the base station and the base stations in the surrounding radio zones determine the availability of the radio channel (communication channel) based on the reported reception level information. About the method.

[0002]

2. Description of the Related Art Conventionally, in a digital mobile communication system, a base station notifies a busy mobile station of a monitoring channel (normal control channel) of a wireless zone around a wireless zone in which the mobile station is located. The mobile station that has received the notification measures the reception level of the monitoring channel in the surrounding wireless zone using the idle time of the time division multiplexing method. The mobile station that has performed the measurement sorts, among the measured reception levels, those that satisfy the condition notified from the base station, for example, those that satisfy a certain level or higher, in order of level, and reports the monitoring channel and the reception level to the base station. The mobile station also measures the reception level of the communication channel and reports the reception level to the base station.
At the base station, from the reception level information reported from the mobile station,
It is determined whether it is time to switch zones. That is, when the reception level of the communication channel is lower than a predetermined value, or when the maximum reception level of the monitoring channel is higher than the reception level of the communication channel by a predetermined value or more, it is determined that the zone is to be switched and the maximum reception level is monitored. Sends the reception level to the base station in the radio zone of the channel, and inquires whether the reception level is a communication level or, if the communication level is available, whether there is an idle communication channel, that is, inquires about the channel state of the channel switching. When the communication is available and there is an idle communication channel and the notification of the channel number is received, the mobile station is instructed to switch to the communication channel.

[0003] In each of the base stations and the size of each radio zone, which is determined by the limit of the average traffic volume of the radio zone, each radio zone the ground situation of or mainly high-rise buildings, fields or from etc. of different radio wave propagation state and the like For each base station, an allowable call reception level of a mobile station in a wireless zone of the base station is determined, and the reference level is set in the base station. Accordingly, when a channel switching time, through
The busy base station is based on the reception level information from the mobile station,
Most receiving level of the line state of the channel switching inquiry
When the channel is not switched by the base station of the monitoring channel with the largest reception level, an inquiry is made to the base station of the monitoring channel with the next highest reception level, and so on.

[0004]

Conventionally, as described above, based on the reception level information reported from the mobile station, the line state inquiry for the channel switching is made to the base station of the monitoring channel in order from the maximum reception level. Was. However, in some cases some cases want as much as possible switch to speech channel of the radio zone but there Ru, maximum reception of the mobile station
In the related art, where the level information is used as the selection condition of the wireless zone, this cannot be performed.

[0005] For example the system has two frequency bands A and B as a multi-band, for example, 800MHz band and 1.5GHz band, the radio zone 1-7 of the frequency band A, as shown in FIG. 5
And the radio zones 1 'to 7 ' of the frequency band B are provided so as to overlap each other with almost the same zone shape, that is, the radio zone 1 and the radio zone 1 'overlap, and the radio zone 2 and the radio zone 2 ′ Overlap, and so on.
You . Base stations 8 to 14 are provided in wireless zones 1 to 7 , respectively, and base stations 8 'to 14' are provided in wireless zones 1 'to 7 ', respectively. ) N1~N 7 are assigned, 'monitoring channel (control channel for each frequency band B in) N1'~N 7' base station 8'～14 is assigned, also the frequency bands a to each of the base stations 8-14 Are allocated, and each of the base stations 8 'to 14' is allocated a plurality of communication channels in the frequency band B. The mobile station 15 can communicate with any of the base stations 9 and 9 'in the wireless zone in which it is located, 2 and 2' in the figure, that is, through any of the monitoring channels and speech channels in the frequency bands A and B. it can. And mobile station 15
As shown in FIG. 6 when passing through the wireless zone accompanying the movement,
Channel switching can be performed from the communication channel of the frequency band A to the communication channel of the frequency band A, and from the communication channel of the frequency band A to the communication channel of the frequency band B, respectively.
Similarly, the channel can be switched from the communication channel of the frequency band B to any of the communication channels of the frequency band B or A.

As described above, a plurality of frequency bands, for example, 800 MHz
In a mobile communication system accommodating the z-band and the 1.5-GHz band, the base station gives a mobile station that is in a call a peripheral radio zone that covers a plurality of frequency bands, that is, a peripheral radio zone that uses the 800 MHz band and a 1.5-GHz band. When notifying the monitoring channels of the peripheral wireless zones in use, the mobile station measures each of the monitoring channels, and, among the measured ones, the one that satisfies the condition to be notified by the base station, the number of zones notified by the base station, Report in order of reception level. Therefore, if the frequency band is different, a difference in superiority is generated due to a difference in propagation characteristics.
In spite of the reception level that allows communication in the 1.5 GHz band, the mobile station reports only a monitoring channel in the frequency band with good propagation characteristics, for example, the 800 MHz band,
There is a possibility that the communication channel of the frequency band (800 MHz) will be congested.

[0007] From such a point, when the base station notifies the mobile station of the monitoring channel of the surrounding radio zone, the monitoring channels of the frequency bands A and B are notified and the propagation characteristics of the frequencies A and B are changed. The correction value α for correcting the underlying level difference is also notified, and the mobile station performs correction by adding the correction value α to each of the frequency bands B in the measured reception level. The corrected reception level and frequency band It is conceivable that the reception level of A is sorted in order of level, and the reception level is reported to the base station.

However, in this case, the following problem may occur. The mobile station sorts the channels for which correction has been performed and the channels for which correction has not been performed in order of level without relation, and reports the result to the base station (base station 8 ) in the radio zone (zone 1) during the call.
Regardless of whether the level of the monitoring channel notified from the mobile station is corrected or not, the base station 8
The base station 9 in the zone 2 is inquired about the radio line using the reception level reported from the mobile station in the radio zone (zone 2) having the highest reception level as information. The base station 9 of the zone 2 receiving the inquiry determines whether the reception level received as the information is a level at which communication is possible in the zone 2 and, if there is a free line, returns the free line to the base station 8 of the inquiry source. Then, the mobile station actually switches the channel to the vacant line in the zone 2, but since the reception level received as information by the inquired base station 9 is corrected, the actual level is changed in the wireless zone. When the level is less than the level at which the call can be made, the quality of the call deteriorates after the channel is switched, and the base station 9 is controlled again to search for the channel switch destination, and the level is corrected. If a wireless zone for the monitoring channel is selected, the above operation is repeated, and there is a possibility that the frequency fluctuates.

[0009]

According to the first aspect of the present invention , a plurality of frequency bands are used for a service area, and
The station can communicate with the base station in any of its frequency bands,
In the mobile station, the measured reception level of the monitoring channel
Make corrections across the wavenumber bands, and
Report to the station, correct the reception level at the base station, and
Undo the correction in.

[0010] According to the second aspect of the present invention, the base station is connected to the line.
When judging the availability, the reception level reported from the mobile station is used.
Perform by correcting the bell. In other words, at the base station
If you want to switch channels as much as possible,
Reception level obtained by adding a certain level to that reception level
Inquired by the user and conversely switched the channel
If not, subtract a certain level from the reported reception level.
An inquiry is made at the calculated reception level.

[0011]

EXAMPLES First a description will be given of an embodiment of the invention of claim 1 with reference to FIG. If mobile base station received the reported neighboring radio zone and its reception level from station 1 (Step S ₁₎ is the correction to the maximum reception level has been performed, the level was returned to the level before correction as information, receiving Peripheral radio with the highest level
A signal for inquiring about a wireless line is transmitted to the base station 2 in the zone 2 (step S ₂ ). The base station 2 receives the inquiry then satisfies the condition reception level of the mobile station sent the information <br/> can call on that zone, and if there is a vacant line, to contact the base station 1 It returns a response there is free access to (step S _3). Upon receiving the response, the base station 1 notifies the mobile station in communication (step S ₄ ), and the mobile station switches the channel to the notified zone 2 frequency (step S ₅ ).

A case where this embodiment is applied to the mobile communication system shown in FIG. 5 will be specifically described with reference to FIG.
Mobile station 15 is in wireless zone 2 of wireless zone number 2;
The base station 9 in the wireless zone 2 notifies the mobile station 15 of the monitoring channel number of the surrounding wireless zone. At this time, since the mobile station 15 is in a call in the frequency band A, first, as shown in FIG. notifies each monitoring channel numbers N1, N 3 near zone number 1 and 3 of the strip a, then notifies the correction level alpha, then the peripheral zone number 1 in the frequency band B ',
2 ', 3' monitoring channel numbers N1 ', N2', N
Notify 3 '. The mobile station 15 having received the notification measures the reception level of the monitoring channel from the peripheral wireless zone, and monitors the monitoring channels N1, N2, N3, N1 ', N2', N3 '.
Are respectively E1, E2, E3, E1 ',
E2 'and E3', as shown in FIG. 3A. The mobile station 15 further includes a monitor channel N of the frequency band B.
1 ', N2', 'reception level E 1 of the' N3, E2 ', E
3 'is added to the correction value .alpha., And then sorted in order of level as shown in FIG. 3B. As shown in FIG. 2C, the zone numbers and their reception levels are sorted in order of level, and the corrected reception level is used as the base station. Report to 9.

The base station 9 having received the report of the reception level information first monitors the monitoring channel number N having the highest reception level.
The wireless zone 1 'is determined from the wireless zone 1', and the base station 8 'of the wireless zone 1' is inquired about the wireless line using the level obtained by converting the reception level E1 '+ α to the level E1' before correction as reception level information. (FIG. 4). The base station 8 'that has received the inquiry determines whether the received level E1' is a level at which communication is possible and, if there is an available line and a vacant line, determines the channel code of that line at the base station of the inquiry destination. 9 Receiving the notification, the base station 9 currently engaged in the communication notifies the mobile station 15 to switch to the channel code reported, and the mobile station 15 completes the zone transfer by switching to the communication channel.

According to the second aspect of the present invention, the present invention can be applied to a case where the mobile communication system uses one frequency band and a case where the mobile communication system uses a plurality of frequency bands.
Is notified only of the monitoring channels N1, N3 and N4 in the peripheral zone, and notifies the base station 9 of the measured reception levels E1, E3 and E4 of the monitoring channels N1, N3 and N4 together with the corresponding monitoring channels. In the case where the reception level E1 is the maximum at the base station 9, if it is desired to switch to the communication channel of the base station 8 of the monitoring channel N1 as much as possible, the reception level E1
Then, the base station 8 is inquired of the wireless line as the reception level by adding the correction value β to 1. Since the received level of the received signal is high at the base station 8, it is usually higher than the reference value, and a free line is searched.

Conversely, if the reception level E1 is the maximum, but it is not desired to switch to the communication channel of the base station 8, E1
The correction value γ is subtracted from 1 and the base station 8 is inquired about the wireless channel as the reception level. In this case, there is a large possibility that a response indicating that the reception level becomes lower than the reference value of the base station 8 and the switching cannot be performed is obtained. Further, when the level of the communication channel of the mobile station 15 becomes close to a state in which communication is not possible, it is necessary to immediately switch to the communication channel of any one of the radio zones. What is necessary is just to add a constant value to the level and use it as the reception level at the time of inquiring the wireless link to each base station.

Performing correction on the reception level reported from the mobile station as described above can be applied to the case where a plurality of frequency bands are used. In this case, the correction is performed to the level before correction at the mobile station. For example, when the addition correction value α at the mobile station is 5 dB, the correction at the base station is not a subtraction of 5 dB, but is a 3 dB subtraction. Switching can be performed with priority, and quality can be prevented from being degraded when the switching is performed.

When a plurality of frequency bands are used in the above description, the present invention is not limited to two frequency bands. Further, the present invention can be applied not only to the time division multiplexing system but also to the frequency division multiplexing system and the code division multiplexing system. In this case, not only the transceiver in the communication channel but also the transceiver in the monitoring channel is provided, It enables the measurement of the reception level of the inside monitoring channel.

[0018]

As described above, according to the present invention, channel switching can be preferentially performed according to the level of a communication channel, or channel switching can be performed in a certain radio zone, or vice versa. Is not performed.

Further, in the channel switching over a plurality of frequency bands, the mobile station can perform level correction to prevent bias due to the difference in frequency band when selecting a line, and to maintain sufficient communication quality at the time of channel switching. Further, when returning the corrected level to the level before the correction, it is possible to control the traffic by operating the value on the base station side and disperse the load, which is extremely useful in practical use.

[Brief description of the drawings]

Figure 1 is a flow chart of a process embodiment of the invention of claim 1.

2A is a block diagram showing an example of a mobile communication system to which the invention of claim 1 is applied, FIG. 2B is a diagram showing an example of a peripheral zone monitoring channel notification signal from a base station to a mobile station, and FIG. FIG. 11 is a diagram illustrating an example of reporting reception level information to a base station.

FIG. 3A is a diagram showing an example of a monitoring channel reception level and a correction state in a mobile station, and FIG. 3B is a diagram showing a level order sort after the correction.

FIG. 4 is a diagram showing a state of a wireless line inquiry from a base station during a call to a peripheral base station.

FIG. 5 is a block diagram showing an example of a mobile communication system using two frequency bands.

FIG. 6 is a diagram showing frequency band transition at the time of channel switching in FIG. 5;

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Seizo Onoe 2-10-1 Toranomon, Minato-ku, Tokyo Inside NTT Mobile Communication Network Co., Ltd. (56) References JP-A-7-38943 ( JP, A) JP-A-7-23447 (JP, A) JP-A-6-351060 (JP, A) JP-A-6-237217 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) H04B 7/24-7/26 102 H04Q 7/00-7/38

Claims (2)

(57) [Claims] Claims: 1. A service area is covered by a plurality of wireless zones, a base station is provided in each wireless zone, and communication is performed during communication.
The mobile station measures the reception level of the monitoring channel in the peripheral wireless zone notified from the base station of the mobile station during communication , reports the measured reception level information to the base station in communication,
The station will determine the appropriate frequency based on the reported reception level information.
Select a base station in the local wireless zone, and
The base station of the mobile station receives the signal received from the base station in communication.
In the wireless communication channel control method of determining whether or not a wireless communication channel can be used based on level information, the reception level information reported to the communicating base station may include:
Received from the communicating base station to the measured reception level
The corrected reception level is obtained by adding the corrected correction value, and the base station in the peripheral wireless zone is
The received reception level information is higher than the corrected reception level.
A radio channel control method for mobile communication, wherein the reception level is obtained by subtracting the correction value . 2. The service area is covered by a plurality of wireless zones.
And establish base stations in each wireless zone,
Surveillance channel of peripheral wireless zone notified from base station
The mobile station measures the reception level of the
Report the communication level information to the communicating base station, and
The station will determine the appropriate frequency based on the reported reception level information.
Select a base station in the local wireless zone, and select the selected base station.
Sends out the reception level information corresponding to the
Base station in the line zone received from the communicating base station
Judge whether wireless line can be used based on reception level information
In the mobile communication radio channel control method, the reception level information reported to the communicating base station is
The measured reception level is set, and the base station in the peripheral wireless zone is
The received reception level information is the measured reception level.
And a correction value added to the mobile communication line.