Radio transmission method for a mobile radio system

• US 4,596,042 A
• Filed: 12/08/1983
• Issued: 06/17/1986
• Est. Priority Date: 12/21/1982
• Status: Expired due to Fees

• Current Assignee: BBC Brown Boveri & Company Limited (ABB Limited)
• Original Assignee: BBC Brown Boveri & Company Limited (ABB Limited)
• Inventors: Stangl, Horst
• Primary Examiner(s): NG, JIN FAY
• Application Number:
  US06/559,262
• Time in Patent Office: 922 Days
• Field of Search: 455/10, 455/11, 455/17, 455/32, 455/33, 455/49, 455/52, 455/54, 455/56, 455/58, 179/2 EB, 340/825.44, 340/825.48
• US Class Current: 455/524
• CPC Class Codes: H04H 20/67 Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 36/305 Handover due to radio link failure control signalling for hand-off failure H04W36/0079
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

In a radio transmission method for a mobile radio system, a link between a mobile station and a central station is established via one of several base stations. The selection of the base station is done by the mobile station in accordance with radio-engineering criteria, and only the transmitter of the selected base station is keyed. This makes the method economical with respect to frequencies, on the one hand, and on the other hand, requires little operational effort for the chain of base stations.

Claims

1. A radio transmission method for a mobile radio system, wherein for the purpose of establishing a radio link between a central station and a mobile station at least two base stations defining at least adjacent service areas are provided, said base stations each including a transmitter and a receiver and exchanging low-frequency signals with the central station, comprising:

said mobile station itself selecting at least one of said base stations for establishing a radio link between said mobile station and the central station; and

keying the transmitter of only the selected base station for maintenance of said radio link with said mobile station;

wherein said step of said mobile station itself selecting at least one of said base stations comprises;

said mobile station initiating a search cycle in which said base stations are successively called by the mobile station, the transmitter of a base station receiving a call from said mobile station being keyed for the purpose of sending a R.F. acknowledgement signal acknowledging a received call from said mobile station, said mobile station receiving said R.F. acknowledgement signal and stopping said search cycle upon receiving said R.F. acknowledgement signal, said mobile station commencing radio traffic with the base station from which said R.F. acknowledgement signal is received;

said mobile station first initiating said search cycle with reduced R.F. sensitivity; and

said mobile station continuing said search cycle in the event that no R.F. acknowledgement signal is received during operation with said reduced R.F. sensitivity by varying the sensitivity of the mobile station to a greater R.F. sensitivity if the mobile station has not received an R.F. acknowledgement signal from a base station during operation in the search cycle at reduced R.F. sensitivity.

2. A method according to claim 1, comprising:

controlling the keying of the transmitter by a signal from the mobile station; and

said mobile station again selecting a base station in the event of an interruption of the radio link between the mobile station and the selected base station.

3. A method according to claim 2, comprising:

said mobile station automatically selecting a new base station in the event that said mobile station leaves the service area of a base station with which the mobile station was in communication by means of said radio link.

4. A method according to claim 1, comprising:

assigning to each base station a respective low-frequency call signal;

the mobile station in the search cycle transmitting sequentially said call signals of the respective base stations; and

keying the transmitter of the base station which first detects the reception of a respective call signal.

5. A radio transmission method for a mobile radio system, wherein for the purpose of establishing a radio link between a central station and a mobile station at least two base stations defining at least adjacent sevice areas are provided, said base stations each including a transmitter and a receiver and exchanging low-frequency signals with the central station, comprising:

said mobile station itself selecting at least one of said base stations for establishing a radio link between said mobile station and the central station; and

keying the transmitter of only the selected base station for maintenance of said radio link with said mobile station;

7. A method according to claim 5, wherein for the purpose of transmitting the selective call in the search cycle, the base stations are successively called by the central station, the selective call is transmitted by respective base station called by the central station to the mobile station, and the central station repeats the successive calling of the base stations until the mobile station acknowledges the receipt of the selective call or until a preset number of successive calls to said base stations has been made by said central station.

6. wherein for the purpose of establishing a radio link from the central station to the mobile station, a selective call is transmitted from the central station via a base station selected by the central station to the mobile station and the mobile station on receiving said selective call acknowledges the receipt thereof and initiates the selection of a base station to maintain said radio link.

8. A method according to claim 6, comprising:

assigning each base station a control signal; and

said central station calling said base stations by means of the respective control signals associated therewith.

9. A radio transmission method for a mobile radio system, wherein for the purpose of establishing a radio link between a central station and a mobile station at least two base stations defining at least adjacent service areas are provided, said base stations each including a transmitter and a receiver and exchanging low-frequency signals with the central station, comprising:

said mobile station itself selecting at least one of said base stations for establishing a radio link between said mobile station and the central station; and

keying the transmitter of only the selected base station for maintenance of said radio link with said mobile station;

wherein after a radio link has been established between the mobile station and the central station via a selected base station, the method further comprises;

locking out the remaining base stations; and

said mobile station transmitting a selective call to the central station to be used by said central station as an acknowledgement signal indicating establishment of said radio link.