JP3047645B2 - Mobile communication system - Google Patents

Abstract

PURPOSE:To attain communication with high quality by solving deterioration problem in the communication quality attended with movement of a mobile equipment during its talking state in the mobile communication system. CONSTITUTION:In the mobile communication system comprising plural mobile equipments, plural radio base stations 151-154, and a switch 11 of an exchange control station in which a mobile equipment at a zone border makes communication with the plural radio base stations 151-154 via plural paths simultaneously, the exchange control station sets a multiple address communication virtual path addressed to the plural radio base stations 151-154 in advance to the switch 11 in its station, and when a mobile equipment comes to a zone border of the plural radio base stations 151-154, the mobile equipment selects the multiple address communication virtual path set in advance to the plural radio base stations 151-154 and makes communication therethrough.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly to a mobile communication system using a broadcast virtual path.

[0002]

2. Description of the Related Art FIG. 3 is a system block diagram showing one configuration example of a general mobile communication system. Exchange control station 31
Has a switch 34, and the switch 34 is
5A, 35B, and 35C are accommodated and connected to the radio base stations 321, 322,. The mobile units 331, 332, to 33m are scattered.

In FIG. 3, a mobile station 331 is connected to a radio base station 32.
Shows a state of communicating with the outside trunk 35A and through the first and switch 34.

In general, one of the features of the mobile communication system is a movement of the mobile device during a call, the mobile station rather have switched the radio base station communicating with the mobile. 3, when the mobile station 331 is Ru come closer to the wireless base station 322 moves,
Mobile 331 in turn would make a call to through a radio base station 332. At this time, the switch 34 in the switching control station 31 is switched, and the connection between the external trunk 35A and the radio base station 322 is established . As described above, in the mobile communication system, it is necessary to control the switching of the radio base station during a call as the mobile device moves. This is called handoff.

In a conventional time-division switch used as a switch in a switching control station, a broadcast trunk placed after the switch is generally used to broadcast to a plurality of destinations. In this case, in order to switch from one-to-one to broadcasting, the connection of the switch must be temporarily switched to a broadcasting trunk, and paths from the broadcasting trunk to a plurality of required destinations must be set.

[0006]

The above-described general handoff requires switching of the switching control station, which causes a short interruption of about several tens of milliseconds in the conventional art, which causes a problem in call quality and also causes a problem in handoff. As the number of times increases, the processing load on the switching control station increases, which causes a problem. This occurs particularly when the mobile station is near the boundary between the coverage areas of the two radio base stations, and frequent handoffs occur as the mobile station moves back and forth near the boundary.

[0007] The handoff is mainly caused by a change in the distance from the radio base station due to the movement of the mobile station. In addition to this, even a small movement causes a deterioration in speech quality due to shadowing and fading. Some countermeasures are needed for

[0008] Shadow I ring occurs by radio waves are blocked by the influence of obstacles, also fading due to cross by moving the terminal in a spatial standing wave produced by the coupling wave of a plurality of reflected waves . Since both changes greatly received level at the mobile for a few tens of cm, it was Tsu there a problem that it is impossible to apply switching same channel as the conventional handoff control.

[0009] with respect to the channel switching of the problem, radio
In the vicinity of the boundary of the coverage area of the base station, a method (hereinafter referred to as soft handoff) in which the mobile station communicates with a plurality of wireless base stations using a plurality of wireless paths is conceivable.
In this case, a plurality of radio base stations and the appropriate external trunk
It is necessary to set up a broadcast path during the period. However, setting a broadcast path to a plurality of specific radio base stations each time as the mobile device moves increases processing overhead. There is a problem.

An object of the present invention is to provide a broadcast virtual path for broadcasting to a combination of a plurality of radio base stations which may be handed off .
Flip leave because set, if the switching is needed is to provide a mobile communication method to communicate by selecting those falling from these distribution for a virtual path.

[0011]

According to Means for Solving the Problems] The present invention, a plurality of mobile stations, a plurality of radio base stations, composed of an exchange controlling station
In the mobile communication system that will be the exchange control station may be set to broadcast a virtual path set addressed beforehand Me plurality of the radio base station to the switch of the local station, the mobile station is in contact next to the Boundary area of wireless base station zone
When moving into the area ,
Wherein it is set Me beforehand movement, characterized in that it comprises means for communicating by switching the virtual path for the broadcast
A communication system is obtained .

[0012]

According to the present invention, switching delay and processing overhead when performing soft handoff are greatly reduced.

[0013]

Next, the present invention will be described with reference to the drawings. First, a switch used in the mobile communication system of the present invention will be described. The switch used in the mobile communication system of the present invention is a head drive type switch. This is a method in which information is divided into short chunks called packets (or cells) and switching (routing) is performed according to information written in a header area of each packet. An ATM switch is an example of the header-driven switch. A
Although various configurations of the TM switch are conceivable, here, one of them will be described as an example with reference to FIG.

FIG. 2 is a partial block diagram of a mobile communication system showing one application example of the present invention. Referring to FIG.
The system of the application example is an ATM switch 21, header translators 221, 222,..., 22n provided for each incoming line of the ATM switch 21 , a DMUX address generation memory 23, and an ATM switch 21 provided for each outgoing line. From the internal receiving units 241, 242, ..., 24n
Ru is configured.

Next, the operation of this application example will be described.
The packet input to the header translator 221 has a path identifier a written in the header. The header translator 221 determines the path identifier a of the input packet, and if the path identifier a indicates a one-to-one path, generates an outgoing line identifier indicating the outgoing line and adds it to the input packet. After that, the data is input to the ATM switch 21. In the ATM switch 21, the packet is broadcast to each outgoing line, and the receiving units 241 to 24n receive the outgoing line identifier and receive only the packet addressed to itself. On the other hand, if the path identifier a of the input packet is for a broadcast path, the header translator 221 temporarily converts the path identifier a into a global path identifier a '. The path identifier a is a unique number only within the input line, while the global path identifier a 'is a unique value for all n input lines.

The global path identifier a 'is input to the DMUX address generation memory 23, and a bit map sequence for designating a plurality of outgoing lines is generated. The generated bit map sequence is synchronized with the input packet and the receiving unit 24 of each outgoing line.
, 24n, and receiving units 241 and 241 of each outgoing line.
.., 24n receive the broadcast packet synchronously only when “1” is set in the bit position assigned to the self by looking at the bit map sequence.

In order to set a broadcast path in a switch having such a configuration, first, a unique global path identifier a 'is selected for each input line as a whole, and a global path identifier a' and a unique input line specific Of the input line header translators 221,.
22n, and a pair of the global path identifier a 'and the corresponding outgoing line bitmap string must be registered in the DMUX address generation memory 23. In mobile communication, the above-described registration must be performed instantaneously because the path changes as the mobile device moves.

In general, if there are m radio base stations, the combination for broadcasting them is m! There is a street. However, in order to perform soft handoff in mobile communication, the number of radio base stations to be broadcast is limited to adjacent zones, and usually , two or at most three paths are sufficient at the same time. Thus the total number of paths that need to be set Me beforehand by the system of the present invention is ₂ C _m or ₃ C _m street, the total number is within the practical range.

FIG. 1 is a block diagram showing the configuration of an embodiment of the mobile communication system according to the present invention. Refer to FIG.
In this embodiment, the switch 11 and the packetizer 12
1, 122 and header translators 131, 132
, The DMUX address generation memory 14 and the wireless base station 1
51, 152, 153 and 154 . Each radio base station 151 for the sake of simplicity, ~, 154 zone and those are arranged one-dimensionally as shown in FIG. 1
And, soft hand-off is necessary because of the adjacent radio base stations
Only the boundaries between coverage areas .

In this case, the broadcast group for performing the soft handoff is group 1 consisting of the radio base stations 151 and 15.
2, group 2 has only three combinations of wireless base stations 152 and 153, and group 3 has only three combinations of wireless base stations 153 and 154.

First, the header translators 131 and 1
32, local path identifiers x1, y1, z1 and x2, y2, z for three broadcast groups, respectively.
2 and global path identifiers G11, G12, G13
And a correspondence table of G21, G22 and G23 are registered. Here, Gij is an identifier of a broadcast path from the line i to the broadcast group j. The path identifiers x1 and x2 may be the same, but all Gij must be unique. Further, the DMUX address generation memory 14 includes
A set of a global path identifier Gij and a bitmap string indicating an outgoing line (in FIG. 1, global path identifiers G11 and G2
1 is “1100”, global path identifiers G12 and G2
2 is “0110”, global path identifiers G13 and G2
3 registers “0011”).

In actual communication, the packetizing device 1
2i packetizes the information and writes the path identifier area of the header. For example, the mobile station connected to the line 1 is connected to the coverage area of the radio base station 151 and the radio base station 1.
When the packetizer 121 reaches the boundary with the cover area 52, the packetizer 121 writes x1 as the path identifier of the header. The header translator 131 generates a global path identifier G11 from the path identifier x1 and inputs it to the DMUX address generation memory 14. The DMUX address generation memory 14 generates a bitmap “1100” corresponding to the corresponding outgoing line from the global path identifier G11, whereby the packet is transmitted to the radio base station 151 and the radio base station 15.
2 only.

[0023]

As described above, the present invention can be applied to a case where a broadcast path is switched during a call by moving a mobile unit.
Except for changing the path identifier locally in the header addition section
No processing is required, so processing is better than conventional methods
That it has a effect that the amount is remarkably reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a mobile communication system according to the present invention.

FIG. 2 is a partial block diagram of a mobile communication system showing one application example of the present invention.

FIG. 3 is a system block diagram showing one configuration example of a general mobile communication system.

[Explanation of symbols]

11, 34 Switch 14, 23 DMUX address generation memory 21 ATM switch 31 Switching control station 121, 122 Packetizer 131, 132, 221, 222, ..., 22n Header translator 151, 152, 153, 154, 321, 322,
, 32n Wireless base station 241, 242, ..., 24n Receiver 331, 332, ..., 33m Mobile 35A, 35B, 35C External trunk

Claims (1)

(57) [Claims] 1. A plurality of mobile stations, a plurality of radio base stations,
Exchange control station Te mobile communication system odor <br/> that consists of the, the exchange control station or rough to the switch of the local station
Flip have set up because a plurality of the virtual path for the broadcast set addressed radio base station, the plurality of radio when the mobile station has come to move to the border region of the zone of the radio base station in contact with adjacent It said comprising means for communicating by switching the virtual path for the broadcast that has been beforehand Me set of base stations addressed
Mobile communication system, characterized in that that.