Abstract: A device receives a communication request for a time division multiple access (TDMA) communication. Upon receipt of the communication request, the device identifies a first communication channel that currently has at least one available TDMA slot and that is currently supporting a greatest number of active TDMA communications amongst a plurality of communication channels. Once the device identifies the first communication channel, the device allocates a first available TDMA slot for the TDMA communication on the first communication channel.

Abstract: A system and method for effectively and reliably terminating a voice call in any burst within a multi-burst superframe. A transmitting unit generates a termination burst upon detecting a dekey event. The termination burst includes a data synchronization pattern, a slot type field indicating an end of a call, and an information field surrounding the data synchronization pattern and the slot type field. The information field is encoded from a predetermined voice encoder frame unique to the termination burst. Once all buffered voice information is transmitted, the termination burst is transmitted prior to the end of the multi-burst superframe. A base station or other receiving unit monitors the incoming signal. Upon detecting the data synchronization pattern, the receiving unit decodes the slot type field and the information field.

Abstract: A transmission capability of a mobile station that requests to be affiliated with a talk group is received. It is then determined whether to alter a current transmission mode of the talk group based at least in part upon the transmission capability of the mobile station, the current transmission mode of the talk group, and the transmission mode of one or more radio frequency (RF) sites associated with the talk group.

Abstract: A method of key distribution includes generating, by a first system device (101), key material and forwarding the key material from the first system device (101) to a second system device (107). It is determined whether a mobile station (401), for which the key material is directed, is active on the system. When the mobile station is active, the key material is forwarded to a base station (115) where the mobile station (401) is active, and the base station (115) forwards the key material to the mobile station (401).

Abstract: A receiving device in a trunked radio communications system determines a transmit frequency, wherein the transmit frequency is calculated by subtracting a voice channel number from 319, multiplying by a channel spacing and adding a base frequency to yield the transmit frequency, if the voice channel number is between 319 and 0. The receiving device determines a receive frequency by 851.0125 MHz+[(319?a voice channel number)*25,000 Hz], if the voice channel number is between 319 and 0. In any case, the voice channel number is communicated in an outbound signaling message defined by Motorola's 3600-baud radio trunking protocol.

Abstract: A receiving device in a trunked radio communications system determines a transmit frequency, wherein the transmit frequency is calculated by subtracting 440 from a voice channel number, multiplying by a channel spacing and adding a base frequency to yield the transmit frequency, if the voice channel number is between 440 and 559. The receiving device determines a receive frequency by 851.0250 MHz+[(a voice channel number?440)*25,000 Hz], if the voice channel number is between 440 and 559. In any case, the voice channel number is communicated in an outbound signaling message defined by Motorola's 3600-baud radio trunking protocol.

Abstract: Methods are described that enable host devices of a multicast IP network to reliably join multicast group address(es) in talkgroup or point-to-point calls. For a talkgroup call, a sourcing host sends “hello” packets or payload to one or more network devices, addressed to a multicast group address. The receiving host issues a join command to the one or more network devices in an attempt to reliably join the multicast group address. If any packets are received by the receiving host within a designated time period associated with the attempt, the receiving host is reliably joined to the multicast group address. For a point-to-point call, a controller sends a pair of multicast group addresses, one designated for sourcing packets and the other designated for receiving packets, to a first and second host participating in the point-to-point call. The designated “source” and “receive” multicast group address are complementary for the first and second hosts.

Abstract: A method includes receiving an authentication request from a mobile station (401) and determining whether to forward the request to an authentication agent. When it is determined to forward the request, the request is forwarded to the authentication agent (107). A random number and a random seed are received from the authentication agent (107). The random number and the random seed are forwarded to the mobile station (401). A response to the random number and the random seed from the mobile station (401) is received and forwarded to the authentication agent (107). The authentication agent (107) compares the response with an expected response. When the authentication agent (107) authenticates the mobile station (401), a derived cipher key is received from the authentication agent (107).

Abstract: A multi-axial roll-forming apparatus that is configured to be quickly and efficiently modifiable so as to allow the formation of a variety of differently shaped component pieces from a variety of different shaped pieces of material. A variously adjustable roll-forming device is held in a variety of vertical and horizontal orientations within a variously adjustable frame. The variously adjustable frame allows for various adjustments so as to provide an aperture consistent with the dimensions of the material being processed or the pieces which are to be formed.

Abstract: A receiving device in a trunked radio communications system determines transmit and receive frequencies by a mapping. The receiving device receives a voice channel number, wherein the voice channel number is communicated in an outbound signaling message defined by Motorola's 3600-baud radio trunking protocol. The receiving device tunes to about a transmit frequency of 806.0250 MHz, if the voice channel number is 440; tunes to about a transmit frequency of 806.0500 MHz, if the voice channel number is 441; tunes to about a transmit frequency of 806.0750 MHz, if the voice channel number is 442; etc. The receiving devices tunes to about a receive frequency of 852.5250 MHz, if the voice channel number is 500; tunes to about a receive frequency of 852.5500 MHz, if the voice channel number is 501; tunes to about a receive frequency of 852.5750 MHz, if the voice channel number is 502; etc.

Abstract: A receiving device in a trunked radio communications system requests a voice channel for a communication and receives an outbound signaling message on a control channel comprising a voice channel number for the receiving device to utilize for the communication. The receiving device tunes to about a transmit frequency, wherein the transmit frequency is determined by multiplying the voice channel number by a channel spacing and adding a base frequency to yield the transmit frequency, if the voice channel number is between 0 and 119. The receiving device modulates the communication to about the transmit frequency and transmits the modulated communication with a transmit deviation that relates to a maximum of 4 kHz.

Abstract: Methods are disclosed for determining a link Op from among a plurality of host devices on a LAN, for exchanging control messages between a communication server and one or more sites having a link Op and a listening Op and for the link Op and/or listening Op to detect and recover from missing packets in a sequence of IP packets received from the server. The link Op and listening Op join a control multicast group address to receive control messages from the server. The link Op establishes a reliable message transfer session with the server. Upon the link Op detecting a missing packet, the link Op may request that the communication server resend the packet. Upon the listening Op detecting a missing packet, the listening Op determines whether the link Op will request retransmission of the missing packet.

Abstract: A method of call control in a packet-based communication system having consoles, distributed among one or more console sites, that are adapted to monitor talkgroup calls. The console sites are served by console site links having a limited available bandwidth. Upon receiving a request for a talkgroup call, there is identified a number of priority consoles requesting participation in a talkgroup call. For example, the priority consoles (or console operators) may indicate that monitoring of the talkgroup call is “critical” for those consoles. Based on the location of the priority consoles, a number of priority console sites are identified for the talkgroup call. If sufficient bandwidth (e.g., call units of bandwidth) is available (or made available) to each of the priority console sites, the call is granted. Alternatively or additionally, the call may be granted to certain non-priority console sites if bandwidth is available.

Abstract: A multi-axial roll-forming apparatus that is configured to be quickly and efficiently modifiable so as to allow the formation of a variety of differently shaped component pieces from a variety of different shaped pieces of material. A variously adjustable roll-forming device is held in a variety of vertical and horizontal orientations within a variously adjustable frame. The variously adjustable frame allows for various adjustments so as to provide an aperture consistent with the dimensions of the material being processed or the pieces which are to be formed.

Abstract: From an unusable site, one or more communication units selects a usable site, thereby reducing missed communications. First, a manager determines (201, 401, 601) that a site is unusable for a predetermined set of communication unit(s). The predetermined set of communication units may include one or more individual communication units or communication units that are affiliated with a particular talkgroup at a particular time. A zone controller (104) identifies (205, 405, 605) any communication units from the set that are registered at the unusable site. The zone controller sends (207, 407, 607) a message to the identified units to assist them in leaving the site. The communication units search (303, 505, 709) the near sites for usability and register (307, 515, 713) at new usable sites. An algorithm is provided to stagger registration by communication units at usable sites.

Abstract: Method and apparatus for updating a subscriber unit with an announcement group identification. A subscriber unit (210) requests affiliation (301) with a talk group (202) and an unknown announcement group identification is issued (315) in response to the request for affiliation. The present invention includes an embodiment where information that identifies which subscriber unit (210) received the unknown announcement group signal is stored (309). An updated announcement signal is subsequently sent to the subscriber unit (210) when a zone controller (114) receives an updated announcement group identification.

Abstract: Systems and methods for implementing dispatch calls using IP multicasting protocols are disclosed. The methods include utilizing a payload multicast group address for distributing payload, and utilizing a control multicast group address for distributing control messages to members of the talkgroup in a single-zone (FIG. 1). A zone controller 116 dynamically identifies payload and control multicast group addresses and sends them to participating sites 102, 104. The participating sites 102, 104 issue Join commands to associated network devices 108, 110 to receive payload and control messages addressed to the respective payload and control multicast group addresses. There is further disclosed a system and method for implementing dispatch calls for members in multiple zones (FIG. 6). Zone controllers 630, 632 separately identify control multicast group addresses and send them to affiliating devices in their respective zones.

Abstract: A method of sending (321) a service utilization message in a communication system (100) includes the steps of forming (303 through 317) a service utilization message and sending (321) the service utilization message via a service port (109). The service utilization message includes a header, a service controller packet, and a service manager packet. The header includes a block source field (201), a block destination field (203), a block length field (205), and a block command type field (207). The service controller packet includes a block opcode field (209) and a controller packet (211). The service manager packet includes a manager packet (213) and a block sequence number field (215). The service utilization messages assist with call billing and call logging for communication systems (100). A service utilization linking message is similarly formed (503 through 517) and sent (521).

Abstract: A method of key distribution includes generating, by a first system device (101), key material and forwarding the key material from the first system device (101) to a second system device (107). It is determined whether a mobile station (401), for which the key material is directed, is active on the system. When the mobile station is active, the key material is forwarded to a base station (115) where the mobile station (401) is active, and the base station (115) forwards the key material to the mobile station (401).

Abstract: A method includes receiving an authentication request from a mobile station (401) and determining whether to forward the request to an authentication agent. When it is determined to forward the request, the request is forwarded to the authentication agent (107). A random number and a random seed are received from the authentication agent (107). The random number and the random seed are forwarded to the mobile station (401). A response to the random number and the random seed from the mobile station (401) is received and forwarded to the authentication agent (107). The authentication agent (107) compares the response with an expected response. When the authentication agent (107) authenticates the mobile station (401), a derived cipher key is received from the authentication agent (107).