Mobile communication system

• US 20050096033A1
• Filed: 08/27/2004
• Published: 05/05/2005
• Est. Priority Date: 08/29/2003
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi Communication Technologies, Ltd. (Hitachi, Ltd.), Hitachi Hybrid Network Co., Ltd. (Hitachi, Ltd.)
• Inventors: Miyawaki, Katsushi, Takahashi, Yuuichi
• Granted Patent: US 7,376,120 B2
• Time in Patent Office: Days
• US Class Current: 455/422.1
• CPC Class Codes: H04B 7/2687 Inter base stations synchronisation
• CPC Class Codes: H04W 84/16 WPBX [Wireless Private Branch Exchange]

Abstract

In the case of radio base stations of different kinds, a synchronization in a radio section cannot be established so that the efficiently effective use of electric waves cannot be retained. According to the invention, therefore, there is provided a TDMA type mobile communication system 100 comprising: a plurality of radio base stations of different system kinds (i.e., a general type radio base station 1, an IP connection type radio base station 10 and a main digital cordless phone 2); mobile phones 5A and 5B wirelessly connected with the plural radio base stations; and a private branch exchange 4 wired with the radio base stations. The radio base station receives, when a synchronized operation mode is decided, a frame signal containing a control CH signal, from a reference radio base station (i.e., a reference station); and times the transmission of the frame signal of a local station to the transmission position of the control CH signal in the frame signal, thereby to establish a frame synchronization in a radio section between own station and the reference radio base station.

Claims

1. A mobile communication system comprising:

a plurality of radio base stations whose system types are different each other;

mobile phones wirelessly connected with the plural radio base stations; and

a private branch exchange wired with the plural radio base stations, wherein

when the radio base station detects a synchronized operation mode setting, the radio base station receives a frame signal containing a control CH signal, from a reference radio base station which is one of the plural radio base stations except own station and is selected for reference to a frame synchronization, and matches transmission timing of the frame signal of own station with a transmission position of the control CH signal in the frame signal, whereby a frame synchronization in a radio section between own station and the reference radio base station is established.

2. A mobile communication system according to claim 1, wherein

the mobile communication system has radio synchronous conditions including a calling code indicating an identical system group between radio base stations, a threshold level which decides whether or not the reception level between the radio base stations is satisfactory, and an additional ID added to each group of the individual radio base stations,

when the radio base station receives a frame signal containing a control CH signal from the radio base station except own station, the radio base station detects the calling code, the reception level and the additional ID of the radio base station which transmitted the frame signal, on the basis of control information contained in the control CH signal of the frame signal, and determines the radio base station as a reference radio base station of frame synchronization, if the calling codes of the radio base station and own are identical, the reception level between the radio base station and own station is equal to or more than a threshold level, and it is decided that the radio base station satisfies all the conditions, on the basis of the comparison of the additional ID between the radio base station and own station.

3. A mobile communication system according to claim 1, wherein

when the present time becomes a preset one in case a synchronous state cannot be held in the radio section between own station and the reference radio base station, the radio base station receives the frame signal containing the control CH signal from the reference radio base station selected again;

and matches the transmission timing of the frame signal of own station with a transmission position of the control CH signal in the frame signal, whereby a frame synchronization in the radio section between own station and the reference radio base station is established.

4. A mobile communication system according to claim 2, wherein

when the present time becomes a preset one in case a synchronous state cannot be held in the radio section between own station and the reference radio base station, the radio base station receives the frame signal containing the control CH signal from the reference radio base station selected again;

and matches the transmission timing of the frame signal of own station with a transmission position of the control CH signal in the frame signal, whereby a frame synchronization in the radio section between own station and the reference radio base station is established.

5. A mobile communication system according to claim 1, wherein

when the radio base station detects the synchronized operation mode setting, the radio base station starts a preset period timer, and starts the operation in a self operation mode to output electric waves of the frame signal at an arbitrary transmission timing of own station, in case the frame synchronization in the radio section between own station and the reference radio base station cannot be established till the predetermined period timer is up.

6. A mobile communication system according to claim 2, wherein

when the radio base station detects the synchronized operation mode setting, the radio base station starts a preset period timer, and starts the operation in a self operation mode to output electric waves of the frame signal at an arbitrary transmission timing of own station, in case the frame synchronization in the radio section between own station and the reference radio base station cannot be established till the predetermined period timer is up.

7. A mobile communication system according to claim 1, wherein:

the radio base station has operation modes including a self operation mode, in which the electric waves of the frame signal are outputted at an arbitrary transmission timing of own station, and a synchronized operation mode, in which the electric waves of the frame signal of own station are outputted after the frame synchronization in the radio section between own station and the reference radio base station was established; and

the private branch exchange can change the operation modes of each of the radio base stations to the self operation mode or the synchronized operation mode, in response to a predetermined operation.

8. A mobile communication system according to claim 2, wherein:

the radio base station has operation modes including a self operation mode, in which the electric waves of the frame signal are outputted at an arbitrary transmission timing of own station, and a synchronized operation mode, in which the electric waves of the frame signal of own station are outputted after the frame synchronization in the radio section between own station and the reference radio base station was established; and

the private branch exchange can change the operation modes of each of the radio base stations to the self operation mode or the synchronized operation mode, in response to a predetermined operation.

9. A mobile communication system according to claim 1, wherein:

the mobile communication system has additional IDs added to each group of the radio base stations; and

after the frame synchronization was established in the radio section between own station and the reference radio base station, the radio base station controls start timing of a segregation control for determining the transmission position of the control CH signal of own station, so as to do not overlap the transmission position of the control CH signal of the radio base station except own station, on the basis of the timer period resulting from the accumulation of the less significant effective bit number of the additional ID of own station and the reference timer period.

10. A mobile communication system according to claim 2, wherein:

the mobile communication system has additional IDs added to each group of the radio base stations; and

after the frame synchronization was established in the radio section between own station and the reference radio base station, the radio base station controls start timing of a segregation control for determining the transmission position of the control CH signal of own station, so as to do not overlap the transmission position of the control CH signal of the radio base station except own station, on the basis of the timer period resulting from the accumulation of the less significant effective bit number of the additional ID of own station and the reference timer period.

11. A radio base station which communicates with a mobile phone, wherein

when the radio base station detects a synchronized operation mode setting, the radio base station receives a frame signal containing a control CH signal, from a reference radio base station which is one of radio base stations accommodated by a private branch exchange except own station and is selected for reference to a frame synchronization, and matches transmission timing of the frame signal of own station with a transmission position of the control CH signal in the frame signal, whereby a frame synchronization in a radio section between own station and the reference radio base station is established.

12. A radio base station according to claim 11, wherein when the present time becomes a preset one in case a synchronous state cannot be held in the radio section between own station and the reference radio base station, the radio base station receives the frame signal containing the control CH signal from the reference radio base station selected again;

and matches the transmission timing of the frame signal of own station with a transmission position of the control CH signal in the frame signal, whereby a frame synchronization in the radio section between own station and the reference radio base station is established.

13. A radio base station according to claim 11, wherein

when the radio base station detects the synchronized operation mode setting, the radio base station starts a preset period timer, and starts the operation in a self operation mode to output electric waves of the frame signal at an arbitrary transmission timing of own station, in case the frame synchronization in the radio section between own station and the reference radio base station cannot be established till the predetermined period timer is up.

14. A radio base station according to claim 11, wherein

the radio base station has operation modes including a self operation mode, in which the electric waves of the frame signal are outputted at an arbitrary transmission timing of own station, and a synchronized operation mode, in which the electric waves of the frame signal of own station are outputted after the frame synchronization in the radio section between own station and the reference radio base station was established.

15. A radio base station according to claim 11, wherein:

the radio base station has additional ID added to each group of radio base stations; and

after the frame synchronization was established in the radio section between own station and the reference radio base station, the radio base station controls start timing of a segregation control for determining the transmission position of the control CH signal of own station, so as to do not overlap the transmission position of the control CH signal of the radio base station except own station, on the basis of the timer period resulting from the accumulation of the less significant effective bit number of the additional ID of own station and the reference timer period.

16. A frame synchronization establishing method for a mobile communication system comprising:

a plurality of radio base stations whose system types are different each other;

mobile phones wirelessly connected with the plural radio base stations; and

a private branch exchange wired with the plural radio base stations, wherein

when the radio base station detects a synchronized operation mode setting, the radio base station receives a frame signal containing a control CH signal, from a reference radio base station which is one of the plural radio base stations except own station and is selected for reference to a frame synchronization, and matches transmission timing of the frame signal of own station with a transmission position of the control CH signal in the frame signal, whereby a frame synchronization in a radio section between own station and the reference radio base station is established.