JP3070751B2 - Switching destination channel selection method in mobile communication - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for selecting an empty channel to be switched to at the time of channel switching in a mobile communication system.

[Prior Art] FIG. 1 shows an example of the configuration of a mobile communication system to which the present invention is applied. In Figure 1, 1 is the line control station, 2 mobile station 3 ₁ to 3 ₄ denotes a base station. Also, an example in which the TDMA system is adopted as the wireless channel multiplex access system is shown, where f _{1 to} f ₄ indicate frequency numbers and t _{1 to} t ₃ indicate channel numbers. FIG. ₁ shows only communication from the mobile device 2 to the base station 31. In the radio zone of each base station (hereinafter simply referred to as zones), the base station 3 _first zone, the mobile station 2 uses the channel t _2. Similarly, in the zone of base station 3 ₂ , channel t ₁ , channel t ₃ , base station 3 ₃
On channel t _3, the channel t ₁ at the base station 3 ₄ zones are used.

In Figure 1, when the mobile station 2 moves the zone of the base station 3 _1, to continue communication by switching the idle channel frequency within the adjacent base station zone. A functional block diagram of a base station 3 ₁ to 3 ₄ and the line control station 1 necessary for realizing the conventional scheme for channel selection of the switching destination is shown in Figure 2.

In Figure 2, 4 is a central control unit in the network control station 1, 5 communication quality comparison device, ₆₁ through ₄ the central control unit of each base station 3 ₁ to 3 _4, 7 _{1-7 4} channels Assignment management table, 8 ₁
8 ₄ transceiver frequency used in the own station, 9 ₁ to 9 ₄ receiver frequency used in the other stations, the 10 ₁ to 10 ₄ of the received signal from each channel of the frequency used in the own station communication quality measuring apparatus for measuring communication quality, 11 ₁ to 11 ₄ represents the communication quality measuring apparatus for measuring the communication quality of the received signal from a particular channel frequency used by the other stations.

Hereinafter, a conventional method of selecting an empty channel as a switching destination at the time of channel switching will be described with reference to FIGS. Data from the mobile station 2 through the channel t ₂ of frequency f _1,
Is received by the transceiver ₈₁ of the base station 3 in _1, the communication quality is measured by the communication quality measuring apparatus 10 _1. When the mobile station 2 moves the zone of the base station 3 _1, the communication quality measuring apparatus 10 ₁
Detects deterioration of the communication quality, the central control unit ₆₁ the frequency f ₁ through, transmits a communication quality deterioration notification signal including the information of the channel t ₂ on the line control station 1.

Transmitting the network control station 1 receives the communication quality deterioration report signal, the central control unit 4 to each adjacent base station 3 _{two or} three ₄ frequency f _1, the communication quality monitoring request signal including information of the channel t ₂ I do. Each base station 3 _{two or} three _4, the central control unit 6 _{2-6 4}
Frequency f ₁ to be measured in the receiver 9 _{2-9 4,} the channel t ₂
Set.

Frequency f ₁ communication quality measuring apparatus 11 _{2-11 4} receive receiver 9 _{2-9 4} and measures the signal quality of communication channel t _2, the communication line control station 1 through the central control unit 6 _{2-6 4} Submit quality information.

In the line control station, the communication quality comparison device 5 compares the communication quality information received from each base station.

In Figure 1, for example, when the reception signal communication quality of the base station 3 ₂ is the best communication quality comparison device 5 selects the base station 3 ₂ as the switching destination base station, the base station 3 ₂ through the central control unit 4 To transmit a channel allocation request signal.

The base station 3 ₂ searches a free channel by using the central control unit 6 ₂ channel allocation management table 7. As a result, in the example of FIG. 1, allocates the empty channel t ₂ of frequency f _2, and transmits the allocation frequency number f ₂ and channel numbers t ₂ to the line control station 1.

Line control station 1 notifies the mobile station 2 to the frequency number f ₂ and channel numbers t ₂ through the base station 3 _1, mobile station 2 is the frequency f ₁ a used channel, the frequency f ₂ from the channel t _2, the channel
It switched to t _2. FIG. 4 shows a control sequence between the mobile station, the base station, and the line control station according to the conventional method described above.

[Problems to be Solved by the Invention] In the conventional switching destination channel selection method as described above, the communication quality of the received signal is measured by the adjacent base station, and only the idle channel of the base station having the best communication quality is selected. However, since the channel position relationship before and after the switching is not taken into consideration, there is a drawback that an instantaneous interruption may occur at the time of channel switching.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a switching destination channel selection method that can solve the conventional problem that a short interruption of communication occurs at the time of channel switching as described above.

[Means for Solving the Problems] The present invention has been made to solve the conventional problems as described above.

That is, the present invention provides a first means for each base station to manage an empty channel position in a zone and a communication channel position of each mobile station, and a designated communication channel position and an empty channel position in its own zone. And a second means for comparing, when the mobile station changes zones, the serving base station of the mobile station uses the first means to search for the channel position during communication, and Notify each adjacent base station of its channel position through the control station, and each adjacent base station searches for an empty channel position using the first means, according to the request of the line control station, and uses the second means. The communication channel position is compared with each of the idle channel positions, and an idle channel having a time zone different from the time slot of the active channel is reported to the circuit control station. Station channel A switching destination channel selection method of selecting a switching destination channel.

[Operation] The present invention has a function of comparing the position of a communicating channel in a zone of a base station before switching and the position of each vacant channel in a zone of an adjacent base station when the channel control station switches channels. The most important feature. Then, by performing channel switching in consideration of the positional relationship,
This can prevent momentary interruption at the time of channel switching.

In the prior art, when selecting a switching destination channel at the time of channel switching, an adjacent base station simply selects an empty channel of a base station having the best communication quality of a signal received from a mobile station. The present invention is different from the first embodiment in that an idle channel is selected in consideration of the communication channel before switching and the idle channel positions of adjacent base stations.

[Embodiment] FIG. 3 shows a functional block diagram of the base station 3 and the line control station 1 necessary for realizing the switching destination channel selection method of the present invention. In FIG. 3, reference numerals 4 to 11 are the same as those of the conventional system shown in FIG. 12 is a channel position comparing device.

Hereinafter, the switching destination channel selection method of the present invention will be described with reference to FIGS. By mobile station 2 moves the zone of the base station 3 _1, from the communication quality measuring apparatus 10 ₁ of the base station 3 ₁ detects deterioration of the communication quality in each adjacent base stations 3 _{2-3 4,} the The procedure until the communication quality of the frequency f ₁ and the channel t ₂ used by the mobile station 2 is measured is the same as the conventional scheme.

In the present invention, further in the neighboring base stations 3 _{2-3 4,} by the central control unit 6 _{2-6 4-channel} allocation management table 7 ₂ -
7 ₄ was used to search for all available channel in the own station zone, and sends the idle channel number to the search, the use of channel numbers t ₂ of the mobile station 2 to the channel position comparison device 12 _{2-12 4.}

In the channel position comparison device 12 _{2-12 4} compares the in-use channel number t ₂ of the mobile station 2 and the idle channel number entered, select the location of the channel different from the in-use channel numbers t _2, the channel number It sends to the central control unit 6 _{2-6 4.}
In the example of FIG. 1, the channel t ₁ in the base station 3 _3, select the base station 3 ₄ for channel t _3, and sends the information that the base station 3 _2, no channel to the central control unit 6 _{2-6 4.}

Each central control unit 6 _{2-6 4} notifies the communication quality information with these channel numbers to the line control station 1. The network control station 1, by the central control unit 4, based on the channel number transmitted from each base station 3 _{two or} three _4, the base station having a free channel position different from the in-use channel numbers t ₂ of the mobile station 2 The communication quality information is sent to the communication quality comparison device 5.

In the example of FIG. 1, and sends the communication quality information of the base station 3 ₃ and the base station 3 _4. The communication quality comparison device 5 compares these pieces of communication quality information and selects a base station having the best communication quality.

In Figure 1, for example, when more of the communication quality in the base station 3 ₃ good, the communication quality comparison device 5 selects the base station 3 ₃ as the switching destination base station, by the central control unit 4,
Transmitting channel allocation request signal to the base station 3 _3. Base station 3 ₃
Then, the frequency f ₃ and the channel t ₁ are allocated using the channel allocation management table 7.

The line control station 1 notifies the frequency number f ₃ and channel number t ₁ to the mobile station 2 through the base station 3 _1, mobile station 2
Changes the used channel to the frequency f ₁ , the channel t ₂ to the frequency f ₃ ,
Switch to the channel t _1. FIG. 5 shows a control sequence between the mobile station, the base station, and the line control station in the above-described switching channel selection method of the present invention.

As is clear from the above, it is understood that the channel switching in which the instantaneous interruption occurs in the conventional switching destination channel selection method can be realized without instantaneous interruption by the present invention.

Note that, in the present embodiment, an example has been shown in which the positional relationship between channels is given the highest priority and the base station having the highest communication quality is selected as the switching destination from among the base stations having empty channels having the allowed positional relationship. However, the same effect can be obtained by selecting a base station having a vacant channel having an allowed positional relationship from among base stations that give allowed communication quality with emphasis on communication quality.

[Effects of the Invention] As described above, the present invention compares a communication channel position before switching with a free channel position in a zone of an adjacent base station at the time of channel switching. This is advantageous in that instantaneous interruption of communication can be prevented.

INDUSTRIAL APPLICABILITY The present invention can be generally applied to a communication system that performs channel switching with a limited channel positional relationship before and after switching at the time of channel switching.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the configuration of a mobile communication system to which the present invention is applied, and FIG. 2 is a functional block diagram of a base station and a line control station necessary for realizing a conventional system related to channel selection of a switching destination. FIG. 3 is a functional block diagram of a base station and a channel control station necessary for realizing the switching destination channel selection method of the present invention. FIG. 4 is a mobile station, a base station, and a conventional switching destination channel selection method. FIG. 5 is a diagram showing a control sequence between circuit control stations, and FIG. 5 is a diagram showing a control sequence between a mobile station, a base station, and a circuit control station according to the switching channel selection method of the present invention. 1 ...... line control station, 2 ...... mobile device, 3 ₁ to 3 ₄ ...... base station,
4 ...... central control unit of the line control station, 5 ...... communication quality comparison device, the central control device ₆₁ through ₄ ...... base station, 7 _{1-7 4} ...... channel allocation management table, 8 _{1-8 4} …… Transceiver / transmitter of the frequency used by own base station, 9 _{1 to} 9 ₄ … Receiver of the frequency used by other base station, 10 ₁ to 10 ₄ …… From each channel of the frequency used by own base station Communication quality measuring device for received signal, 11 ₁
... 11 ₄ …… Communication quality measurement device for signals received from a specific channel of a frequency used by another base station, 12 ₁ … 12 ₄ …… Channel position comparison circuit

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Seigura Onoe 1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-1-141422 (JP, A) Hei 1-183221 (JP, A) JP-A-64-12628 (JP, A)

Claims (1)

(57) [Claims] A mobile communication system in which a communication service area is divided into a plurality of wireless zones, a base station is provided in each wireless zone, and a line control station for controlling a wireless channel of each wireless zone is connected to each base station. In the system, each base station has first means for managing an empty channel position in a wireless zone and a communication channel position of each mobile station, and a designated communication channel position and an empty channel position in its own wireless zone. And a second means for comparing the mobile station, when the mobile device shifts the wireless zone, the serving base station of the mobile device searches for the communication channel position using the first means, Notifying each adjacent base station of its channel position through the line control station, each adjacent base station searches for an empty channel position using the first means according to the request of the line control station, and executes the second means. Using the communication The middle channel position is compared with each empty channel position, and an idle channel in a time zone different from the time slot of the communication channel is reported to the circuit controller. The circuit controller changes the channel of the base station having the empty channel. A switching destination channel selection method, wherein a switching destination channel is selected.