Abstract: A state machine for data link control is implemented in the state management of a second layer protocol of a subscriber unit, which establishes message transmissions and management with an RP and an RPCU. In an acquiring state, the subscriber unit scans frequencies to find an available channel and downlinks information of system channels from the RPCU. The system channels include a first channel and a second channel. In a standby state, the subscriber unit keeps receiving the information, and the standby state includes an initial state, an idle state, and a time slot waiting state. The initial state is for determining and comparing the information and confirming whether the first channel is changed and whether the subscriber unit is registered. The idle state is to wait for a message that requests to establish a TC from the third layer protocol and to determine whether the second channel belongs to normal call messages, informing the third layer protocol to make a corresponding response.

Abstract: A data link control device which is implemented in a Layer 2 Protocol of a subscriber unit in order to establish and maintain data link between the subscriber unit and a radio port. In which, the Layer 2 Protocol is located between a physical layer and a Layer 3 Protocol. The data link control device comprises a media access control module, a state control module and a data processing module. The media access control module transmits and receives data between the subscriber unit and the radio port. The state control module controls and manages the flow of states of the subscriber unit. States in the state control module can be classified as Off State, Acquiring State, Standby State, and Active State. According to system information channel (SIC) message and alerting channel (AC) message received, or requests from the state control module, the data processing module carries out corresponding actions to the state control module.

Abstract: A Personal Access Communications System (PACS) subscriber unit (SU) layer 3 interface is designed as a finite state machine that includes a unique slot seizing state. All transitions from a null state that require traffic channel seizing first transition to the slot seizing state before transitioning to another associated handling state. While in the slot seizing state, the SU layer 3 interface state machine awaits confirmation of traffic channel establishment.

Abstract: A Personal Access Communications System (PACS) subscriber unit (SU) layer 3 interface is designed as a finite state machine that includes a unique slot seizing state. All transitions from a null state that require traffic channel seizing first transition to the slot seizing state before transitioning to another associated handling state. While in the slot seizing state, the SU layer 3 interface state machine awaits confirmation of traffic channel establishment.

Abstract: In a method of updating a set of candidate frequency channels during wireless communications between a radio port and a mobile communications device, the communications device switches to a current measured one of multiple pre-stored frequency channels not in a current set of candidate frequency channels to measure signal quality after an assigned time slot of a current time frame of a second time sequence, and switches back to a current working frequency channel prior to the assigned time slot of a succeeding time frame of a first time sequence. The mobile communications device updates a current set of the candidate frequency channels with the current measured frequency channel when the signal quality attributed to the current measured frequency channel is better than those attributed to the current set of the candidate frequency channels.