Method and apparatus for transitioning between control channels in a cellular system

In a telecommunications system having at least one base station transmitting on a plurality of control channels, including an analog control channel (ACCH) and at least one digital control channel (DCCH), and at least one mobile station, a method of transitioning a mobile station between control channels, said method comprising the steps of:

• moving into an idle state on an ACCH;
• receiving identifying information over said ACCH, said identifying information including information identifying at least one DCCH, wherein said at least one DCCH is preferred over said ACCH for operation of the mobile station in the system;
• determining if a measurement parameter on said at least one DCCH at said mobile station is greater than a threshold level for triggering transition from said ACCH to said at least one DCCH;
• and
• performing, in response to a positive determination in said step of determining, successive access attempts on said at least one DCCH by repeating the steps of moving onto, receiving, determining and performing access attempts, and for each unsuccessful access attempt incrementing said threshold level by a step increment and returning to said idle state on said ACCH, said successive access attempts performed until said measurement parameter on said at least one DCCH is less than said threshold level.

In a telecommunications system having at least one base station transmitting on a plurality of control channels and at least one mobile station, an apparatus for transitioning a mobile station between control channels, said apparatus comprising:

• (a) means for scanning and selecting a control channel of a first type at the mobile station;
• (b) means for receiving identifying information over said control channel of a first type, said identifying information including information identifying a control channel of a second type, wherein said control channel of a second type is preferred over said control channel of a first type for operation of the mobile station in the system;
• (c) means for determining if a measurement parameter at the mobile station on said control channel of a second type is greater than a threshold level for triggering transition from said control channel of a first type to said control channel of a second type;
• (d) means for performing, in response to a positive determination in said means for determining, an access attempt on said control channel of a second type;
• (e) means, if said access attempt is unsuccessful, for incrementing said threshold level by a step increment;
• and
• (f) means for causing elements (a)-(e) to repeat the functions of scanning and selecting, receiving identifying information, performing an access attempt, and incrementing said threshold level until said access attempt performed by said means for performing an access attempt is successful or until said mobile station otherwise is required to move off said control channel of a first type.

In a telecommunications system having at least one base station transmitting on a plurality of control channels, including an analog control channel (ACCH) and at least one digital control channel (DCCH), and at least one mobile station, an apparatus for transitioning a mobile station between control channels, said apparatus comprising:

• means for maintaining an idle state on an ACCH;
• means for receiving identifying information over said ACCH, said identifying information including information identifying at least one DCCH, wherein said at least one DCCH is preferred over said ACCH for operation of the mobile station to the system;
• means for determining if a measurement parameter on said at least one DCCH at said mobile station is greater than a threshold level for triggering transition from said ACCH to said at least one DCCH;
• means for performing, in response to a positive determination in said means for determining, successive access attempts on said at least one DCCH according to said identifying information received by said means for receiving and according to said determination performed in said means for determining, and for each unsuccessful access attempt incrementing said threshold level by a step increment and returning to said idle state on said ACCH, said successive access attempts performed until said determination performed by said means for determining indicates said measurement parameter on said at least one DCCH is less than said threshold level.