# US 5,711,004 A · Method for minimizing message interruptions during hand-off in a multi-site radio > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,711,004 A - Document ID: US5711004A - Status: Granted - Kind: A - Application number: 08/709,419 - Filed: 1996-09-06 - Granted: 1998-01-20 - Earliest claimed: 1993-07-22 - Assignees: Motorola, Inc. - Inventors: Darek Blasiak; Jeff Pfeil; Paul M. Erickson - Web page: https://patentgrep.com/patent/US5711004A ## CPC - H04W 84/08: Trunked mobile radio systems - H04W 36/302: {due to low signal strength} - H04W 24/00: Supervisory, monitoring or testing arrangements - H04W 36/00: Hand-off or reselection arrangements - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract A multi-site communication system (100) includes a plurality of communication units (106, 107) roaming among communication sites (108-111). The communication sites (108-111) are controlled by a central controller (100), via repeaters (102-105), and are thereby capable of establishing communication among sites. A method for minimizing message interruptions during a hand-off, of a first communication unit between two sites, includes the step of receiving (200) a message (300) from a second communication unit. During the message (300), which may be delivered at varying information rates, the first communication unit determines (202) the signal quality. If the signal quality of the message is unfavorable, the receiving communication unit determines (204) when the varying information rate of the message is favorable for a hand-off. Lastly, when the varying information rate is favorable for a hand-off, the first communication unit requests (205) the hand-off. ## Claims ### Claim 1 In a multi-site, half-duplex, trunked communication system including a first site controller, a second site controller, a transmitting communication unit, and at least one receiving communication unit, a method of minimizing loss of interruptions of a randomly sourced message of unknown duration and varying information rate transmitted over a carrier signal, to cause minimal information loss during a hand-off operation, by any of said at least one receiving unit, from the first site controller to the second site controller, each said at least one receiving unit including a traffic discriminating means for identifying audio holes in the transmission of said message and means for identifying a traffic slow condition, the method comprising the receiving unit performed steps of: analyzing, by the associated traffic discriminating means, the carrier signal as a function of signal quality to identify a degraded signal condition; analyzing, by the associated means for identifying a traffic-slow condition, the sourced message, as a function of at least one of its duration and its information rate, to identify a window-of-favorability condition; and performing a hand-off operation, with minimal information loss, on the basis of said degraded signal condition and said window-of-favorability condition. ### Claim 2 (depends on 1) The method of claim 1, wherein the sourced message includes at least one pause indicator signal, and wherein the step of analyzing the sourced message includes the step of detecting a pause indicator signal. ### Claim 3 (depends on 1) The method of claim 1, wherein the message is followed by an end-of-transmission (EOT) indicator, and wherein the step of analyzing the sourced message includes the step of detecting an EOT indicator. ### Claim 4 (depends on 1) The method of claim 1, wherein the step of analyzing the sourced message includes the step of identifying an audio hole exceeding a predefined period. ### Claim 5 (depends on 4) The method of claim 4, further comprising the step of varying the predefined period as a function of the signal quality of the carrier signal. ### Claim 6 In a multi-site, trunked communication system including a first site controller, a second site controller, a transmitting communication unit, and at least one receiving communication unit, a method of minimizing loss of interruptions of a randomly sourced message of unknown duration and varying information rate transmitted over a carrier signal, to cause minimal information loss during a hand-off operation, by any of said at least one receiving unit, from the first site controller to the second site controller, each said at least one receiving unit including a traffic discriminating means for identifying audio holes in the transmission of said message and means for identifying a traffic slow condition, the method comprising the receiving unit performed steps of: analyzing, by the associated traffic discriminating means, the carrier signal as a function of signal quality to identify a degraded signal condition; analyzing, by the associated means for identifying a traffic-slow condition, the sourced message, as a function of at least one of its duration and its information rate to identify a window-of-favorability condition; and performing a hand-off operation, with minimal information loss, on the basis of said degraded signal condition and said window-of-favorability condition. ### Claim 7 (depends on 6) The method of claim 6, wherein the sourced message includes at least one pause indicator signal, and wherein the step of analyzing the sourced message includes the step of detecting a pause indicator signal. ### Claim 8 (depends on 6) The method of claim 6, wherein the message is followed by an end-of-transmission (EOT) indicator, and wherein the step of analyzing the sourced message includes the step of detecting an EOT indicator. ### Claim 9 (depends on 6) The method of claim 6, wherein the step of analyzing the sourced message includes the step of identifying an audio hole exceeding a predefined period. ### Claim 10 (depends on 9) The method of claim 9, further comprising the step of varying the predefined period as a function of the signal quality of the carrier signal. ### Claim 11 (depends on 6) The method of claim 6, wherein the receiving and transmitting communication units are operably coupled for communication in half-duplex mode. ### Claim 12 (depends on 7) The method of claim 7, wherein the receiving and transmitting communication units are operably coupled for communication in half-duplex mode. ### Claim 13 (depends on 8) The method of claim 8, wherein the receiving and transmitting communication units are operably coupled for communication in half-duplex mode. ### Claim 14 (depends on 9) The method of claim 9, wherein the receiving and transmitting communication units are operably coupled for communication in half-duplex mode. ### Claim 15 (depends on 10) The method of claim 10, wherein the receiving and transmitting communication units are operably coupled for communication in half-duplex mode.