Abstract: A method and apparatus for increasing the probability of successful data frame transmission from a transmitter to a receiver. When a data frame is generated by a processor, it is stored in a transmit queue and a copy of the data frame is stored in a secondary queue. An elapsed time device tracks the elapsed time that the data frame copy has been stored in the secondary queue. When no data frames are generated by the processor, data frame copies from the secondary queue are placed into the transmit queue, thereby increasing the redundancy of transmitted data frames and thus the probability of successful transmission to the receiver.

Abstract: Method and apparatus to prevent system deadlock in a dispatch system by monitoring link activity. The dispatch system is comprised of a set of remote units which communicate with each other by broadcasting one at a time to the group. A remote unit communicates with the other remote units through at least one base station. A communications manager grants a remote unit exclusive system talker status upon request through the base station servicing the requesting remote unit. The base station monitors a series of data from the remote unit designated as the system talker to detect voice activity. The base station sends a surrogate request to the communications manager to relinquish the system talker privilege if the voice activity falls below a predetermined threshold.

Abstract: In a push-to-talk dispatch system, a method and apparatus for providing an accelerated response to a push-to-talk origination message. A first base station allocates a first set of equipment to support a push-to-talk connection. A first system controller allocates a second set of equipment to support the push-to-talk connection. Upon receipt of a push-to-talk origination message from a first remote unit, the first base station transmits an immediate response to the first remote unit, instructing it to communicate through the first set of equipment and the second set of allocated equipment.

Abstract: A method and apparatus to provide access to a dispatch system is disclosed. A communications manager (40) grants an exclusive system talker privilege to one remote unit (10) in the system at a time. After a remote unit (10) requests and is designated as the exclusive system talker, no other remote unit (20, 22) may transmit for a first pre-determined amount of time. After the first pre-determined time has elapsed, any other remote unit (20, 22) may request the exclusive system talker privilege and become the exclusive system talker. The exclusive system talker privilege is revoked by the communications manager (40) to any remote unit who retains the exclusive system talker privilege for more than a second pre-determined amount of time. The exclusive system talker privilege is also revoked upon the release of a push-to-talk button on a remote unit (10).

Abstract: To reduce the power consumption of a remote unit in a dispatch system the remote unit enters a dormant state. A base station transmits a forward link broadcast signal and monitors a common access channel. A first remote unit continually receives and decodes the forward link broadcast signal and determines whether said forward link broadcast signal comprises active signals. If the remote unit determines that the forward link broadcast signal comprises no active signals for some a duration T.sub.1, the first remote unit enters a dormant mode. In the dormant mode the remote unit sporadically receives and decodes said forward link broadcast signal. If this remote unit or any other remote unit on the same net presses a push to talk button, it transmits a message on the common access channel. In response, every remote unit on the net which is in a dormant state exits the dormant state and continually monitors the forward link broadcast signal.

Abstract: In a dispatch system, power of the forward link broadcast channel transmitted from a base station is controlled such that the power level is the minimum necessary and such that transmission of the forward link broadcast channel is terminated if no remote unit is located within the coverage area of the base station. In addition to transmitting a forward link broadcast signal, the base station monitors an access channel. A first remote unit in the base station coverage area receives and decodes the forward link broadcast signal. The first remote unit determines a signal quality of said forward link broadcast signal. If the signal quality is unacceptable, the remote unit transmits a power request access message. The base station responds to the request by increasing the transmission power of forward link broadcast channel. If no requests are received at the base station, the forward link broadcast channel is slowly decreased to a minimum.