Ericsson Ge Mobile Communications Inc.

General Electric Company

Ericsson Gmbh

Houston H Hughes, Iii

Jeffrey S Childress

Marc A Dissosway

Gerald M Cooper

Robert T Gordon

David L Hattey

Bruno Yurman

Dimitri M Nazarenko

Thomas A Brown

Marcella M Tucker

Samuel Maedjaja

Charles L Derenge

Vicki J Teel

Craig F Szczutkowski

James S Kent

Nancy L Hall

Kenneth W Morris

Jeffery S Childress

Dimitri M Nazarenk

David I Hattey

A digitally trunked radio repeater system provides substantial improvements in timeliness and reliability. The mobile radio transceivers transmit channel requests on the control channel at 9600 bps. The mobile transceiver switches to a working channel in response to an assignment message received on the control channel. Message and transmission trunking capabilities are both present so as to maximize working channel usage without compromising channel access for high priority communications. Radios select between message and transmission trunking based on over-the-air signaling. During transmission trunking, called and calling receivers return to the control channel after each transmission (and called transceivers may be inhibited from transmitting) but grant higher priority to calls from the other transceivers being communicated with to ensure continuity over an entire conversation.

Operating a trunked communication system in transmission and message

A RF site link for communicating between a centralized switching system and a plurality of mobile communications RF base stations is disclosed. The RF site link includes a plurality of RF link devices connected to centralized switching equipment. The RF link devices transmit signals to and receive signals from the remote base stations over the same working channels that the base stations use to communicate with the mobile or portable radios within each of the base stations' areas of operation. A RF control link is provided to control the assignment of the working channels between the centralized switching equipment and each of the base stations within the system.

RF site communication link

A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses a much higher digital signalling rate than is typically found in prior art systems, and uses a control channel to convey digital channel request and assignment messages between the central site and mobile transceivers. The mobile radio transceivers transmit channel requests on the control channel (if no response is received, the mobile retries during a retry time window which increases in duration in dependence on the number of retries). The mobile transceiver switches to a working channel in response to an assignment message received on the control channel. Subaudible digital signals transmitted on the control channel and on active working channels allow late entry, shifting to higher priority calls, and other advanced functions. Message and transmission trunking capabilities are both present so as to maximize working channel usage without compromising channel access for high priority communications. During transmission trunking, called and calling receivers return to the control channel after each transmission (and called transceivers may be inhibited from transmitting) but grant higher priority to calls from the other transceivers being communicated with to ensure continuity over an entire conversation. Additional functions and fault tolerant features further increase the versatility and reliability of the system.

Trunked radio repeater system

A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses a much higher digital signalling rate than is typically found in prior art systems, and uses a control channel to convey digital channel request and assignment messages between the central site and mobile transceivers. The mobile radio transceivers transmit channel requests on the control channel (if no response is received, the mobile retries during a retry time window which increases in duration in dependence on the number of retries). The mobile transceiver switches to a working channel in response to an assignment message received on the control channel. Subaudible digital signals transmitted on the control channel and on active working channels allow late entry, shifting to higher priority calls, and other advanced functions. Message and transmission trunking capabilities are both present so as to maximize working channel usage without compromising channel access for high priority communications. During transmission trunking, called and calling receivers return to the control channel after each transmission (and called transceivers may be inhibited from transmitting) but grant higher priority to calls from the other transceivers being communicated with by temporarily disabling the monitoring of the control channel with respect to the remaining other predetermined call groups to ensure continuity over an entire conversation.

Trunked radio repeater system with control channel monitoring feature

A gateway between a non-trunked ('conventional') RF communication system and digitally trunked RD communication system maps between trunked group IDs and non-trunked subaudible signalling tone frequencies. An interface between the two systems thus forms a 'super group' including both trunked and non-trunked radios that can automatically communicate together. The gateway permits a customer to continue to use non-trunked components, and to cost-effectively integrate such components into a state-of-the-art trunked radio communications system.

Conventional network interface for multisite RF trunking system

A single channel autonomous trunking ('SCAT') RF repeater transmits and receives on a single duplex RF channel. The repeater operates alternately in a control channel mode and in an assigned channel mode. Digital control channel signalling results in temporary assignment of the single channel for assigned channel signalling (e.g., mobile generated messages). A holdover time period following reversion of the channel to control channel signalling minimizes collisions and permits priority to be given to emergency communications. Low speed data subaudible digital signalling may be used to provide late entry capabilities.

Single channel autonomous digitally trunked RF communications system

A site architecture for a trunked radio frequency communications system provides better fault tolerance capabilities than are available from architectures including redundant hardware. During normal system operations, a primary site controller performs most or all system control functions while signal processing functions are performed in a distributed manner by trunking cards associated with individual repeater channel receivers and transmitters. In the event the site controller fails, the trunking cards also begin performing trunking and other control functions. The trunking cards cease attempting to communicate with the failed site controller, and begin communicating directly with one another via a high speed backup serial link. Through the distributed processing routines performed by the various trunking cards and interaction between the trunking cards over the backup serial link, trunking and other capabilities are maintained even though the primary site controller has failed (although advanced features such as call logging and the like are lost). Because trunking capability is maintained, failure of the primary site controller has little or no effect on ongoing communications and is virtually transparent to mobile unit operators.

Fail-soft architecture for public trunking system

A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses a much higher digital signalling rate than is typically found in prior art systems, and uses a control channel to convey digital channel request and assignment messages between the central site and mobile transceivers. The mobile radio transceivers transmit channel requests on the control channel (if no response is received, the mobile retries during a retry time window which increases in duration in dependence on the number of retries). The mobile transceiver switches to a working channel in response to an assignment message received on the control channel. Subaudible digital signals transmitted on the control channel and on active working channels allow late entry, shifting to higher priority calls, and other advanced functions. Message and transmission trunking capabilities are both present so as to maximize working channel usage without compromising channel access for high priority communications. During transmission trunking, called and calling transceivers return to the control channel after each transmission (and called transceivers may be inhibited from transmitting) but grant higher priority to calls from the other transceivers being communicated with to ensure continuity over an entire conversation. Additional functions and fault tolerant features further increase the versatility and reliability of the system.

Trunked radio repeater system with multigroup calling feature

A downlink between a communications dispatch console and a digitally trunked radio repeater system site controller efficiently transfers message data between the site controller and the console over a standard 9.2 kilobit per second landline. A downlink trunking card identical in structure to trunking cards used in the preferred embodiment system for RF channel signal processing interfaces the site controller with the landline link. A similar trunking card on the other side of the landline link interfaces the dispatch console processor with the landline link. Message protocol and format is translated between the site controller and the landline link and between the landline link and the dispatch console. Data buffering at each end of the landline link maximizes data transfer rate over the landline, and in addition, a priority scheme insures that more important messages are transmitted over the downlink before less important messages. Retransmit-until-acknowledged protocol is used to insure reliable message transfer--and also to permit receiving units along the downlink to slow down transmitting units in order to avoid message traffic blockage.

Processor-to-processor communications protocol for a public service

A downlink between a communications dispatch console and a digitally trunked radio repeater system site controller efficiently transfers message data between the site controller and the console over a standard 9.2 kilobit per second landline. A downlink trunking card identical in structure to trunking cards used in the preferred embodiment system for RF channel signal processing interfaces the site controller with the landline link. A similar trunking card on the other side of the landline link interfaces the dispatch console processor with the landline link. Message protocol and format is translated between the site controller and the landline link and between the landline link and the dispatch console. Data buffering at each end of the landline link maximizes data transfer rate over the landline, and in addition, a priority scheme insures that more important messages are transmitted over the downlink before less important messages. Retransmit-until-acknowledged protocol is used to insure reliable message transfer--and also to permit receiving units along the downlink to slow down transmitting units in order to avoid message traffic blockage

A digital voter system for a multi-site public service trunking (PST) digitally trunked RF communications system operates on the principle that it is highly likely that messages received during a system redundancy removal period are redundant messages. For a given RF channel, digital receiver is associated with each of multiple sites and receives digital messages reported to it by its associated sites. The multiple digital receivers are connected to a digital selector via a service request line (FSL) and a serial data line (BSL). Digital receivers which have messages to transfer to the digital selector attempt to seize the service request line and, if they successfully seize it, maintain the line in its seized state for the redundancy removal period. Digital receivers which have messages but discover the service request line is already seized simply discard their messages. Since it is likely that two digital receivers may successfully seize the service request line at or near the same time, a windowing technique is used to schedule the times different digital receivers may apply their messages to the serial data line. If a digital receiver sees signals on the serial data line before it is scheduled to begin transmitting, it discards its message and aborts its transmission attempt. The preferred embodiment voter thus handles messages very rapidly (to reduce system latency time) while effectively removing most redundant messages and reducing or eliminating data collision on the shared serial data bus.

Digital voter for multiple site PST R trunking system

A digitally trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses a much higher digital signalling rate than is typically found in prior art systems, and uses a control channel to convey digital channel request and assignment messages between the central site and mobile transceivers. The mobile radio transceivers transmit channel requests on the control channel (if no response is received, the mobile retries during a retry time window which increases in duration in dependence on the number of retries). The mobile transceiver switches to a working channel in response to an assignement message received on the control channel. Subaudible digital signals transmitted on the control channel and on active working channels allow late entry, shifting to higher priority calls, and other advanced functions. Message and transmission trunking capabilities are both present so as to maximize working channel usage without compromising channel access for high priority communciations. During transmission trunking, called and calling transceivers return to the control channel after each transmission (and called transceivers may be inhibited from transmitting) but grant higher priority to calls from the other transceivers being communciated with to ensure continuity over an entire conversation. Additional functions and fault tolerant features further increase the versatility and reliability of the system.

Trunked radio repeater system including synchronization of a control

A digital voter system for a multiple site digitally trunked RF communications system includes an improved voting arrangement which tests for actual redundancy before removing redundant messages--thereby decreasing retransmission traffic in simulcast and other large coverage area RF trunking systems. Status messages indicating ongoing call reception are generated periodically by each receiver site which receives a given call. The status messages are received by a digital voter, which in a clear voice mode is used to determine (in responses to the status messages) whether an analog voter should maintain a clear voice call.

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Lynchburg, VA, United States of America

Houston H Hughes, Iii