Beacon carrier

• US 5,150,362 A
• Filed: 09/06/1990
• Issued: 09/22/1992
• Est. Priority Date: 09/13/1989
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Akerberg, Dag E.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): TON, DANG T
• Application Number:
  US07/578,249
• Time in Patent Office: 747 Days
• Field of Search: 370/95.1, 370/104.1, 379/59, 379/60, 379/62, 379/63, 340/825, 340/441, 340/825.10, 455/33, 455/32, 455/56, 455/54, 455/34, 455/58
• US Class Current: 370/331
• CPC Class Codes: H04B 7/2643 using time-division multiple access [TDMA] H04B7/2615, H04B7/2618 take precedence
• CPC Class Codes: H04W 36/00 Hand-off or reselection arrangements
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

In a cellular mobile radio system a method of choosing at a mobile station an appropriate base station and time slot on a time division multiplexed radio channel for the purpose of call set up or handover, wherein each base station transmits in one time slot of a predetermined control radio channel and, at least once during a multiframe, in each communication radio channel time slot used by the base station for calls, roaming signals comprising information on identity of transmitting base station and communication radio channels available at transmitting base station, the mobile scanning the control and communication channels and when desirous of call set up or handover selecting a base station and a time slot on a communication channel, the mobile desirous of call set up or handover transmitting to the choosen base information on mobile identity and the choosen communication channel time slot.

Claims

1. A method of selecting a base station, radio channel and time slot at a mobile station for call set up or handover in a mobile communication system comprising a plurality of base stations, mobile stations, and time division multiple access radio channels, comprising the steps of:

transmitting from each base station, in each communication radio channel time slot used by the transmitting base station for calls, at least once during a multiframe on the communication channel, roaming signals comprising information on identity of the transmitting base station and communication radio channels available at the transmitting base station;

transmitting from each base station in one time slot of a predetermined control radio channel roaming signals comprising information on identity of the transmitting base station and communication radio channels available at the transmitting base station;

scanning the predetermined control radio channel for receiving satisfactory roaming signals at any mobile station;

scanning communication radio channels available according to received roaming signals for receiving noise and interfering radio signals in time slots unused by the base station at any mobile station desirous of call set up or handover;

storing and updating information on base station identity and available communication radio channels and time slots from radio signals received at any mobile station;

selecting at any mobile station desirous of call set up or handover a base station and a time slot on a communication radio channel for call set up or for handover according to information received in satisfactory roaming signals at the mobile station on the control radio channel and communication radio channel respectively; and

transmitting to the selected base station from the mobile base station desirous of call set up or handover radio signals comprising information on mobile station identity, the selected communication radio channel and the time slot selected.

4. A method according to claim 1 comprising the further steps of:

scanning the control radio channel at each base station for receiving roaming signals transmitted by other base stations;

comparing at each base station the time of receiving roaming signals from other base stations on the control radio channel with the time of transmitting its own roaming signals on the control radio channel in relation to the time of transmitting its own roaming signals on the control radio channel in relation to the time slots of the control channel; and

adjusting at each base station the time of transmission of roaming signals on the control radio channel in view of the result of the comparison.

2. A method of selecting a base station, radio channel and time slot at a mobile station for call set up or handover in a mobile communication system comprising a plurality of base stations, mobile stations, and time division multiple access radio channels, comprising the steps of:

transmitting from each base station, at least once during a multiframe in each communication radio channel time slot used by the transmitting base station for calls, roaming signals comprising information on identity of the transmitting base station;

transmitting from each base station in one time slot of a predetermined control radio channel roaming signals comprising information on identity of the transmitting base station, communication radio channels available at the transmitting base station and time slots unused by the transmitting base station;

broadcasting from each base station paging signals on control and communication channels comprising identitiy of any paged mobile stations;

scanning the predetermined control radio channel for receiving satisfactory roaming signals at any mobile station;

scanning communication radio channels for receiving satisfactory roaming signals comprising base station identity at any mobile station where no satisfactory roaming signals are received when scanning the predetermined control radio channel;

storing and updating information on the base station identity and available communication radio channels and time slots from radio signals received at any mobile station;

selecting at any mobile station paged or desirous of call set up or handover a base station and a time slot on a communication radio channel for call set up or for handover according to information received in satisfactory roaming signals at the mobile station on the control radio channel and communication radio channel respectively; and

transmitting to the selected base station from the mobile station desirous of call set up or handover radio signals comprising information on the mobile station identity on the selected communication radio channel in the time slot selected.

3. A method of choosing a base station, radio channel and time slot at a mobile station for paging, call set up or handover in a mobile communication system comprising a plurality of base stations, mobile stations and time division multiple access radio channels, comrising the steps of:

transmitting from each base station, at least once during a multiframe in each time slot used by the transmitting base station for calls, roaming signals comprising information on identity of the transmitting base station;

transmitting from each base station in one time slot of a predetermined control radio channel roaming signals comprising information on identity of the transmitting base station, communication radio channels available, and time slots unused at the transmitting base station for selection by a mobile sation;

scanning, at any mobile station in an idle state, the predetermined control radio channel periodically during a part of the time in the idle station for receiving satisfactory roaming signals;

scanning communication radio channels periodically during a part of the time in the idle state for receiving satisfactory roaming signals comprising base station identity at any mobile station in the idle state where no satisfactory roaming signals are received when scanning the predetermined control radio channel;

storing and updating information on base station identity and available communication radio channels and time slots from radio signals received at any mobile station desirous of call set up or handover or in the idle state;

selecting, at any mobile station paged or desirous of call set up or handover, a base station and a time slot on a communication radio channel for call set up or for handover according to information received in satisfactory roaming signals at the mobile station on the control radio channel and communication radio channel respectively; and

transmitting, to the selected base station from the mobile station desirous of call set up or handover, radio signals comprising information on mobile station identity on the selected communication radio channel in the time slot selected.

5. In a mobile communication systems including a plurality of base stations, mobile stations, and time division multiple access radio channels, a method for selecting a base station, radio channel and time slot at a mobile station for call set up or handover comprising the steps of:

transmitting roaming signals at least one time from each base station including information on identity of the transmitting base station and communication radio channels available at the transmitting base station during a multiframe in each communication radio channel time slot used by the transmitting base station for calls;

transmitting roaming signals from each base station including information on identity of the transmitting base station and communication radio channels available at the transmitting base station in one time slot of a predetermined control radio channel;

scanning the predetermined control radio channel for satisfactory roaming signals to be received at any mobile station;

scanning the communication radio channels for satisfactory roaming signals, said roaming signals including the transmitting base station identity, to be received at any mobile station where no satisfactory roaming signals are received when scanning the predetermined control radio channel;

storing and updating information on base station identity and available communication radio channels from radio channels received at any mobile station;

selecting at any mobile station desirous of call set up or handover a base station and a time slot on a communication radio channel for call set up or handover according to satisfactory roaming signals received at the mobile station on the control radio channel and communication radio channel respectively; and

transmitting the mobile station identity, the selected communication channel and the selected time slot to the selected base station from the mobile station.

6. In a mobile communication systems including a plurality of base stations, mobile stations, and time division multiple access radio channels, a method for selecting a base station, radio channel and time slot at a mobile station for call set up or handover comprising the steps of:

transmitting roaming signals at least one time from each base station including information on identity of the transmitting base station and communication radio channels available at the transmitting base station during a multiframe in each communication radio channel time slot used by the transmitting base station for calls;

transmitting roaming signals from each base station including information on identity of the transmitting base station, communication radio channels available at the transmitting base station and time slots unused by the transmitting base station in one time slot of a predetermined control radio channel;

transmitting from the base stations paging signals including identity of any paged mobile stations;

scanning the predetermined control radio channel for satisfactory roaming signals to be received at any mobile station;

scanning the communication radio channels for satisfactory roaming signals, said roaming signals including the transmitting base station identity, to be received at any mobile station where no satisfactory roaming signals are received when scanning the predetermined control radio channel;

storing and updating information on base station identity, available communication radio channels and unused time slots from radio channels received at any mobile station;

selecting at any paged mobile station desirous of call set up or handover a base station and a time slot on a communication radio channel for call set up or handover according to satisfactory roaming signals received at the mobile station on the control radio channel and communication radio channel respectively; and

transmitting the mobile station identity on the selected communication channel in the selected time slot to the selected base station from the mobile station.