JPH03295324A - Channel assignment control system in mobile communication - Google Patents

Abstract

PURPOSE:To suppress the increase of interference at the time of the application of reuse partition by using the difference of receiving levels at a mobile station of radio waves from a base station to communicate and the base station of the maximum receiving level among the base stations in the neighborhood. CONSTITUTION:A control channel signal is transmitted from a control channel transmitter 9 through a transmitting and receiving multiplexer 7, a transmitting and receiving demultiplexer 6 and an antenna 5, and the mobile station receives it by a receiver 21 through 18, 19. Then, the position of the mobile station is decided not only by the receiving level with the base station to communicate, but the receiving level with the base station in the neighborhood is measured as well, and distance between the mobile station and the base station is decided by the value of the difference of the receiving level with the base station to communicate and the receiving level with the base station in the neighborhood, and when the decided distance is smaller than a virtual zone radius, a channel for a virtual zone is assigned, and when it is larger than the virtual zone radius, the channel for a regular zone is assigned. Thus, the effect of the reuse partition can be raised by deciding correctly the distance between the mobile station and the base station, and simultaneously, the interference can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mobile communication channel allocation connection control system that can improve the geographical repetition efficiency of frequencies.

(Prior art) In mobile communications, typified by car telephones, radio channels with the same frequency are assigned to radio zones that are over a certain distance, allowing the frequency to be used repeatedly and increasing the frequency utilization rate. Is it common to improve? In land mobile communications, if the distance between a mobile station and a base station is r, the average reception level L (dB) of radio waves can be approximated as L=-10α]ogr+A. α has a value of 3 to 4, and A is a constant determined by antenna gain and transmission power.

FIG. 5 is a diagram explaining frequency repetition, where 1 and 2 are wireless zones that use the same frequency, R is the zone radius, and D
is the repeating zone distance. The radio waves from 2 reach 1 and become interference waves in 1's zone. When the mobile station is at point 0, which is the edge of the zone, the radio waves in its own zone (called desired waves) are at their lowest, and the interference wave level is at its highest. Even in this case, the difference between the desired wave and the interference wave (called D/V)
The repetition distance is determined so that a certain value can be satisfied.

The average desired wave level Lo at point 0 is Lo=-10αl
ogR+A, and the average interference wave level Lu is Lu=-1
Since 0αlog (D - R) + A, if the required value of the difference between the desired wave and the interference wave is A (dB), then Lo""'
Lu=Δ;10αlog ((DR)/R). From this, D=(1+10A/"Oa)-R. That is, the distance between repetition zones is a constant value times the zone radius. The constant value is determined from the required level difference between the desired wave and the interference wave. From this, if we consider a virtual radius R'(R'< R) within the zone of radius R, for a mobile station in the zone of Ro, D' = (1+10'') ') The frequency can be repeated between a virtual zone of radius R' located at a distance of D' determined by Ro.D' = (R' /R)XD, which is a smaller value than D. This is shown in Figure 6.

3 and 4 are virtual small wireless zones.

In this way, virtual small zones are considered within the zone, and frequencies are repeatedly used at closer distances between the small zones to increase frequency efficiency, which is called Leus partition. In the smart partition, the total of channels that are used repeatedly and channels that are used repeatedly between virtual small zones is allocated to each zone.

In a wireless partition, it has conventionally been determined whether a mobile station is within a virtual small zone based on the reception level at the base station. That is, the radio waves from the mobile station are received by the base station and this is 110αlogR'+
If it is higher than A, it is determined that the distance to the base station is less than or equal to R', and a channel for a small zone is assigned.

(Problem M to be solved by the invention) However, the reception level -10a log r + A is the average reception level when the mobile station is in places with various conditions. When used in a building, the reception level is higher than the average reception level, and when used on a narrow road surrounded by buildings or inside a building, the reception level is lower than the average reception level. That is, it cannot be accurately determined whether the mobile station is within the distance Ro from the base station or not based on the reception level alone. Even if you are within R' distance, the reception level is low, so if you mistakenly believe that you are beyond R', you will not be able to use the channels within R, which have higher frequency utilization efficiency, and conversely If it is mistaken that the signal is within R' because the reception level is high even though the signal is far away, a large amount of interference will be caused to the interference zone.

An object of the present invention is to provide a channel allocation control method that can accurately determine the distance between a mobile station and a base station, enhance the effect of Leus partition, and reduce interference.

(Means for Solving the Problems) A feature of the present invention for achieving the above object is that a plurality of wireless zones are provided within a service area as communication areas between base stations, and As well as assigning channels of the same frequency to distant base stations,
In a mobile communication system in which a channel of the same frequency different from the above-mentioned frequency is further allocated to base stations separated by a second fixed distance smaller than the first fixed distance, a communicating base station receives radio waves from a mobile station. The value of the difference between the radio wave level from the mobile station and the received L-bell of the base station with the highest reception level among the base stations surrounding the base station with which to communicate, or the base station with which to communicate and the surrounding base stations The difference in the reception level at the mobile station of the radio waves from the base station with the maximum reception level,
If is above a certain value, the second channel to be repeatedly used at a certain distance is used; if it is below a certain value, the first channel is used.
The present invention relates to a channel allocation control method in mobile communications that uses channels that are repeatedly used over a certain distance.

(Function) The present invention does not judge the location of a mobile station only by the reception level with the base station with which it communicates, but also measures the reception level with surrounding base stations, and Determine the distance between the mobile station and the base station based on the value of the difference between the reception level and the reception level of the surrounding base station, and if the determined distance is smaller than the virtual zone radius, allocate a virtual zone channel, If the radius is larger than the virtual zone radius, a regular zone channel is assigned. This method differs from the conventional technology in that the mobile station position is determined by also using the reception level with neighboring base stations.

(Embodiment) FIG. 1 is a base station configuration example for explaining a first embodiment of the present invention, and FIG. 2 is a mobile station configuration example, with 5.1
8 is an antenna, 6 and 19 are transmitting and receiving duplexers, 7 is a transmitting duplexer, 8 is a receiving distributor, 9 is a control channel transmitter, 10.1
1 is a communication channel transmitter, 12 is a control channel receiver,
13.14 is a communication channel receiver, 15 is a control device, 1
6. 17 is the transmission line between the exchange center, 20 is the transmitter, 21
2 is a receiver, 22 is a synthesizer, 23 is a control section, 24 is a handset, and 25 is a control line with the exchange. A control channel signal is transmitted from the control channel transmitter 9 via 7.6.5, and the mobile station receives it at the receiver 21 via 18.19.

When making a call from a mobile station, from the transmitter 20, 19, 1
A calling signal is sent to the base station via step 8. The calling signal is 5,
6.8 and is received by the control channel receiver 12 through 15
determines the channel to be used for communication with this mobile station, and the control channel transmitter 9 instructs this channel number to the mobile station.

15 is a transmitter (10 to 1) of the determined communication channel.
Start up the receiver (any one of 13 to 14) and the corresponding transmission path (any one of 16 to 17)
The terminal is connected to an exchange (not shown) via the terminal. The mobile station receives the communication channel number instruction signal from the base station at 21, and
3 decodes and controls 22 to switch to the designated channel, and based on this, 22 tunes 20 and 21 to the designated channel. As a result, the transmission line (16 to
17) and 24.

For simplicity, it is assumed that all base stations under consideration use the same control channel frequency. At this time, the calling signal from the mobile station can be received not only by the base stations in the zone where the mobile station is located, but also by some base stations in the surrounding zones.

When each base station receives a calling signal, it measures its reception level and notifies the exchange via the control line 25 along with the calling signal.

The switching center receives call signals with reception levels from multiple base stations, and selects the base station that has reported the highest reception level from among them, and the mobile station that made the call receives the call signal from this base station. First, it is determined that the user resides within the zone. Next, the highest reception level among the reception levels of base stations (peripheral base stations) other than the maximum reception level is selected. Check the reception level of the base station in your area! . .

Let β be the maximum value of the reception level of the surrounding base stations.

FIG. 3 is a diagram illustrating the in-service zone and the surrounding zone, where 26 is the in-service zone, 27, 28 is the surrounding zone, and 29 is the location of the mobile station. Since 29 is closer to 28 than 27, the zone with the maximum reception level among the peripheral zones is 28.

ρ0. ρ. If it is determined that r' is smaller than Ro, a virtual small zone frequency is assigned, and if it is determined that r is greater than Ro, a regular zone frequency is assigned.

When r' = R', the average value of βD + '2 A is -10alog R' + A, -10al, respectively.
og(2R-R')+A, so the difference is 1
0alog ((2R-R')/R). Therefore, the value of l2o-ρ is lOαlog((2R-R')
/R'), it is determined that r'<R', and conversely, if it is smaller, it is determined that r'>R'. If the mobile station is in a unique location for propagation, such as on an elevated road or on a narrow road in a built-up area, ρA + 90 will deviate from the average value, but the difference will be due to the deviation from the average value or canceled out. This means that the mobile station position can be determined accurately.

FIG. 4 is a diagram illustrating the second embodiment, and is a diagram illustrating the second embodiment.
is the TDMA time slot for mobile station reception.

35 to 39 are time slots for mobile station transmission. This figure is an example of 4-channel multiplexed TDMA. It is assumed that the mobile station is communicating with the base station in reception time slots 30, 34, . . . and transmission time slots 36, . 31
33 are reception time slots used by other mobile stations, and 35.37 to 39 are transmission time slots used by other mobile stations. The mobile device sequentially receives transmission waves from neighboring base stations at timings other than its own transmission and reception time slots (time slots 32 and 33), and takes the maximum value as I2A. Since the average value of the reception levels of 30.34... is 12D, the mobile station sends these reception level values I2D and i2A to the exchange using its own transmission time slot 36, so the exchange receives this I2ok.
2g to ρD and 11001o as in the first embodiment.
((21(-R')/R') The position of the mobile station is estimated by comparing the size with ((21(-R')/R'), and if it is determined that it is within the virtual small zone, the frequency is switched to the small zone frequency.

(Effect of the invention) As explained above, the distance between the mobile station and the base station is accurately measured at the start of communication and during communication, and if the distance is less than a certain value, a zone closer than usual is repeatedly used. This has the advantage that it is possible to allocate channels that are already in use, thereby increasing the effectiveness of Leus partitioning, and suppressing the increase in interference when Leus partitioning is applied.

[Brief explanation of the drawing]

1 and 2 are examples of the base station configuration and mobile station configuration for explaining the first embodiment of the present invention, FIG. 3 is a diagram for explaining the serving zone and surrounding zones, and FIG. FIG. 5 is an explanatory diagram of frequency repetition, and FIG. 6 is an explanatory diagram of Leus partition. 1, 2.4.26.27.28...wireless zone, 3.
4... Virtual small zone, 5.18... Antenna, 6.19... Transmission/reception duplexer, 7... Transmission duplexer, 8... Receiving distributor,
9... Control channel transmitter, 10, 11... Communication channel transmitter, 12... Control channel receiver, 13, 14... Communication channel receiver, 15... Control device, 16.17 ...Transmission path, 20...Transmitter, 21...Receiver, 22...Synthesizer, 23...Control unit, 24...Handset,
25...Control line, 30-34...Time slot for mobile station reception, 35-39...Time slot for mobile station transmission.

Claims (1)

[Claims] A plurality of wireless zones are provided within the service area as communication areas between base stations, and channels of the same frequency are assigned to base stations that are separated by a distance greater than a first certain distance, and the distance is smaller than the first certain distance. In a mobile communication system in which a channel of the same frequency different from the above frequency is further allocated between base stations separated by a second fixed distance, the reception level of the radio waves from the mobile station at the communicating base station and the radio wave from the mobile station are determined. The value of the difference between the reception level of the base station with the maximum reception level among the surrounding base stations of the base station with which to communicate, or the value of the difference between the reception level of the base station with the maximum reception level among the base stations with which to communicate and the surrounding base stations. If the difference in the reception level of radio waves at the mobile station is above a certain value, the channel to be repeatedly used at the second certain distance is used, and if it is below the certain value, the channel is to be used repeatedly at the first certain distance. A channel allocation control method in mobile communication characterized by using.