JP2921782B2 - Mobile radio communication system and mobile radio communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for increasing the number of base stations in a mobile communication system and system by superposing and arranging independent radio zones of a plurality of base stations on the same zone. It relates to a communication method in the system.

[0002]

2. Description of the Related Art When the number of mobile stations located in the same wireless zone increases, there is a case where communication from the mobile station cannot be accommodated by only a base station in the wireless zone. In such a case, a method of increasing the number of base station devices can be considered. As a method of adding base stations, a method of arranging an independent wireless zone composed of a plurality of base station devices on the same wireless zone so as to overlap each other is considered.

Conventionally, each base station has a common access channel (CAC) and each common access channel (CAC).
C) contained at least one "perch channel". The “perch channel” is a channel that can be captured when the mobile station is powered on.

For example, when the power is turned on, the mobile station performs the following operation.

(1) The mobile station scans the carrier of the perch channel when it is uniquely stored, and creates a table in order of the intensity of the level.

(2) Synchronizing with the perch channel slot in order from the carrier with the highest level, confirming that the perch channel is a common control channel, and entering a standby state.

[0007]

However, according to the conventional method, when an independent wireless zone by a plurality of base station apparatuses is arranged in a superposed manner on the same wireless zone,
Since each base station apparatus has a perch channel, the following disadvantages occur.

(1) Since the mobile station selects a perch based on the strength of the carrier upon capturing, when two perch channels are provided in the same zone, the perch channel with the stronger carrier is always selected. In this case, the selected perch channel is determined by the slight difference in the intensity of the radio waves output from the two perch channels and the surrounding environment of those perch channels. There is a possibility that there is a bias in the area. In this case, traffic cannot be distributed and accommodated in two perch channels.

(2) Since the number of perch channels that can be provided in a certain area is limited, if a plurality of perch channels are used in one radio zone, the number of perch channels in the surrounding area is reduced. Run short.

The same problem occurs not only when the power of the mobile device is turned on, but also when the mobile device moves from another zone.

The present invention has been made in order to solve the above-mentioned problems.
It is an object of the present invention to provide a method for increasing the number of base station devices capable of effectively using perch channel resources and effectively distributing and accommodating traffic.

[0012]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a service for performing communication with a mobile station through a plurality of radio zones by base stations arranged in a distributed manner. In a mobile radio communication system in which an area is formed and a perch channel stored by the mobile station is arranged in each of the plurality of radio zones, a plurality of radio zones are provided in each of some or all of the plurality of radio zones. Independent radio zones of the plurality of base station devices are overlapped and arranged, and one of the plurality of base station devices has a perch channel, and the other one of the plurality of base station devices The apparatus is characterized in that it does not have a perch channel.

According to a second aspect of the present invention, in the mobile radio communication system according to the first aspect, each of the plurality of base station apparatuses has one control channel, and the mobile station has a unique mobile station number. And a control channel selecting means for determining one control channel used by the mobile station from among the control channels of the plurality of base stations based on the above.

According to a third aspect of the present invention, in the mobile radio communication system according to the second aspect, a broadcast channel transfer unit is used as the control channel selection unit.

According to a fourth aspect of the present invention, a service area for communication to a mobile station is formed by a plurality of radio zones by base stations arranged in a distributed manner, and a perch channel stored in the mobile station is transmitted to the plurality of radio stations. In each of the plurality of radio zones, an independent radio zone by a plurality of base station devices is superimposed on each of some or all of the plurality of radio zones, and the plurality of base station devices are respectively A mobile radio communication method in a mobile radio communication system having one control channel and only one of the plurality of base station devices having a perch channel, wherein the mobile station has a unique mobile station. Control channel selection for determining one control channel used by the mobile station from among the control channels of the plurality of base stations based on a number Characterized by comprising a step.

According to a fifth aspect of the present invention, in the mobile radio communication method according to the fourth aspect, the control channel selecting step includes a broadcast channel transfer step of transferring a broadcast channel.

[0017]

According to the present invention, independent radio zones each composed of a plurality of base station apparatuses are superposed and arranged on the same zone, and a perch channel is provided only in one of the radio zones. A control channel having no perch channel is provided in another wireless zone. A mobile station that has moved from another zone to the zone receives the radio wave output from the perch channel. Thereafter, the mobile station determines a wireless zone to be used by itself based on information output from the perch channel, and uses a control channel in the determined wireless zone.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. In this embodiment, "Digital Car Phone System Standard (RCR STD-27B)" (abbreviated as RCR) issued by the Radio System Development Center.
The communication protocol specified in is used. However, the technical scope of the present invention is not limited to the invention using the communication protocol defined by RCR, as is clear from the description of the claims.

FIG. 1 is an explanatory diagram showing an arrangement of base stations in a radio telephone system embodying the present invention. As shown in FIG. 1, two independent wireless zones (wireless zones 50 and 55) of two base station devices (base station devices 51 and 52) are arranged in an overlapping manner on the same zone. A perch channel (also called a zone-specific control channel) is provided only for the control channel (CCH) of one of the radio zones (radio zone 50), and the perch is provided for the control channel (CCH) of the other radio zone (radio zone 55). No channel is provided.

FIG. 2 is an exemplary diagram showing an arrangement of base stations before overlapping wireless zones. In FIG. 2, a service area is configured by a set of four wireless zones 10, 20, 30, and 40 including four base station devices 11, 21, 31, and 41. One perch channel is arranged in each wireless zone.

FIG. 3 is an explanatory diagram showing the arrangement of base stations when a new wireless zone 25 is superimposed on the wireless zone 20 shown in FIG. As shown in FIG.
The wireless zones are overlapped by adding a new base station 22 at the same place as the base station 1 or near the base station 21.
Such addition of base stations is necessary when traffic in the wireless zone 20 increases. The wireless zone 20 and the wireless zone 25 have respective control channels, but a perch channel is not provided in the control channel of the wireless zone 25.

FIG. 4 is a flowchart showing the operation performed by a mobile station that has moved between radio zones. Specifically, FIG.
The operation of the mobile station 12 will be described by taking as an example a case where the mobile station 12 moves from the wireless zone 10 to the wireless zone 20 in the service area where the base station device 22 is added as shown in FIG. The perch channels of the radio zones 10, 20, 30, and 40 are written in the ROM built in the mobile station 12. Mobile station 12 that has moved to wireless zone 20
Measures the reception level of the carrier of one perch channel written in the ROM (step 10). Next, it is determined whether the reception level is equal to or higher than the cutoff level (step 20). If the reception level is equal to or higher than the cutoff level, the reception level of the perch channel is stored in the memory (RA
M) (step 30). It is determined whether or not the reception levels of all perch channels written in the ROM have been measured (step 40). If all the measurements have not been completed, the process returns to step 10.

When the measurement of the reception level intensities of all the perch channels is completed (step 40), a table is created by sorting the perch channels in the order of the reception levels stored in the memory (step 50). In the case of this embodiment, the perch channels assigned to the radio zone 20 are located at the top of the table, and the perch channels assigned to the radio zones 10, 30, and 40 are below their perception levels. Arrange in order of strength.

An attempt is made to establish synchronization with each perch channel in the order of the created table. First, wireless zone 2
The synchronization is established for the perch channel of 0 (step 60), and the normality of the perch channel is confirmed (step 70). If synchronization cannot be established with the wireless zone 20 or the normality of the perch channel of the wireless zone 20 cannot be confirmed, synchronization is attempted with the next perch channel. Can use a protocol defined by RCR, and is not directly related to the present invention.

A procedure in which a mobile station that has selected a perch determines a control channel (CCH) to be used (steps 80 to 80)
90) are described below.

In this embodiment, two control channels (CCs) of a radio zone 20 and a radio zone 25 are provided on the same zone.
H) is present. Therefore, the mobile station has to decide which control channel to use. Therefore, the base station divides the mobile stations into groups according to mobile station numbers (telephone numbers) unique to the individual mobile stations. The base station transmits the broadcast information (BCC
The control channel to be used by each group is described in the control structure information in H). The broadcast information (BCCH) is a one-way channel for broadcasting control information from the network to the mobile station, and is transmitted once per superframe from the network side to the mobile station.

The mobile stations are divided into, for example, six groups. For example, for mobile stations belonging to the first, third, and fifth groups, the control channel of the wireless zone 20 is designated as a control channel to be used. The mobile stations belonging to the second, fourth and sixth groups are provided with the wireless zone 2
One control channel is designated as a control channel to be used.

The mobile station 12 has a control channel to be used by a group to which the mobile station 12 belongs, which is described in the control channel structure information,
If the control channel is for the wireless zone 20 (step 80), the control channel is used. If the channel is the control channel of the wireless zone 21 (step 8
0), switching to the control channel of the wireless zone 21 is performed (step 90).

It is assumed that the mobile stations 12 are grouped into the second group and the mobile stations 32 are grouped into the fifth group based on the respective mobile station numbers. When moving from the wireless zone 10 to the wireless zone 20, the mobile station 12 determines a control channel to be used as a control channel of the wireless zone 25 based on control channel structure information obtained from a broadcast channel of the wireless zone 20, The control channel of the wireless zone 20 is switched to the control channel of the wireless zone 25. When the mobile station 32 moves from the wireless zone 30 to the wireless zone 20, the control channel to be used is determined as the control channel of the wireless zone 20 based on the control channel structure information obtained from the broadcast channel of the wireless zone 20, and the control channel is used as it is. Used as a control channel.

In the above embodiment, two independent wireless zones each composed of two base station devices are superposed on the same zone. However, the number of base station devices superposed and arranged on the same zone, The number of zones is not limited to two, but due to the increase in traffic in the zone,
The number of superimpositions can be increased as appropriate.

[0031]

As described above, according to the present invention,
The traffic of the mobile station can be dispersed and accommodated by a plurality of base station devices within one wireless zone, and the perch channel resources can be effectively used.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a state in which a plurality of wireless zones are superimposed according to the present invention.

FIG. 2 is an explanatory diagram showing an arrangement of base stations before overlapping wireless zones.

FIG. 3 is an explanatory diagram showing an arrangement of base stations after overlapping wireless zones.

FIG. 4 is a flowchart illustrating an operation performed by a mobile station that has moved between wireless zones.

[Explanation of symbols]

 Reference Signs List 10 wireless zone (with perch channel) 11 base station apparatus 12 mobile station 20 wireless zone (with perch channel) 21 base station apparatus 22 base station apparatus 25 wireless zone (without perch channel) 30 wireless zone (with perch channel) 31 base station Device 32 Mobile station 40 Wireless zone (with perch channel) 41 Base station device 50 Wireless zone (with perch channel) 51 Base station device 52 Base station device 55 Wireless zone (without perch channel) 59 Host device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 7/24-7/26 H04Q 7/00-7/38

Claims (5)

(57) [Claims] 1. A service area for communication with a mobile station is formed by a plurality of radio zones by base stations arranged in a distributed manner, and a perch channel stored in the mobile station is arranged in each of the plurality of radio zones. In a mobile radio communication system, independent radio zones by a plurality of base station devices are superimposed and arranged on each of a part or all of the plurality of radio zones in the plurality of radio zones. A mobile radio communication system, wherein one of the base station apparatuses has a perch channel, and another of the plurality of base station apparatuses does not have a perch channel. 2. The mobile radio communication system according to claim 1, wherein each of the plurality of base station devices has one control channel, and the plurality of base station devices are based on a unique mobile station number of the mobile station. A mobile radio communication system, further comprising control channel selecting means for determining one control channel used by a mobile station from control channels of a base station. 3. The mobile radio communication system according to claim 2, wherein a broadcast channel transfer unit is used as said control channel selection unit. 4. A service area for communication to a mobile station is formed by a plurality of radio zones by base stations arranged in a distributed manner, and a perch channel stored in the mobile station is arranged in each of the plurality of radio zones. Independent radio zones by a plurality of base station devices are arranged in superposition on each of some or all of the radio zones in the plurality of radio zones, and the plurality of base station devices each have one control channel. A mobile radio communication method in a mobile radio communication system in which only one base station device among the plurality of base station devices has a perch channel, based on a unique mobile station number of the mobile station, A control channel selecting step of determining one control channel used by the mobile station from among the control channels of the base station. Mobile radio communication method for the butterflies. 5. The mobile radio communication method according to claim 4, wherein the control channel selecting step includes a broadcast channel transfer step of transmitting a broadcast channel.