Abstract: A first subscriber unit (SU) operating in a two-way radio frequency (RF) communications system having at least one fixed terminal, one or more channels, and a plurality of subscriber units, generates a first burst of data for transmission to the at least one fixed terminal. The first SU calculates a cyclic redundancy check (CRC) or checksum value over (i) at least a first portion of the first burst of data and (ii) at least a portion of a first private data. The first SU transmits the first burst of data and the calculated CRC/checksum value, but not the first private data, to the at least one fixed terminal. The fixed terminal then calculates its own CRC/checksum over the received burst and its own copy of the first private data, and compares the result with the received CRC/checksum. The fixed terminal authenticates the received burst if the values match.

Abstract: A process for resolving call collisions in a digital conventional direct mode includes monitoring a direct mode communication channel for transmissions from other direct mode radios in the plurality of direct mode radios. In response to detecting a new call request: identifying a last radio to transmit on the direct mode channel, transmitting a new call request for receipt by the last direct mode radio to transmit, monitoring the direct mode channel for a response from the last radio to transmit, and if a call grant granting the new call request is received from the last radio to transmit, initiating the new direct mode call on the direct mode communication channel. If the call grant is not received, at least temporarily refraining from initiating the new direct mode call.

Abstract: A process for resolving call collisions in a digital conventional direct mode includes monitoring a direct mode communication channel for transmissions from other direct mode radios in the plurality of direct mode radios. In response to detecting a new call request: identifying a last radio to transmit on the direct mode channel, transmitting a new call request for receipt by the last direct mode radio to transmit, monitoring the direct mode channel for a response from the last radio to transmit, and if a call grant granting the new call request is received from the last radio to transmit, initiating the new direct mode call on the direct mode communication channel. If the call grant is not received, at least temporarily refraining from initiating the new direct mode call.

Abstract: In a peer to peer trunked radio network having a plurality of network locations, each network location includes a plurality of repeaters and a dynamically selected at least temporarily act as a rest channel repeater at each network location. A first repeater at the first network location may determine a first timing at which to broadcast an intra-site beacon and a second timing at which to broadcast an inter-site roaming beacon, the intra-site beacon including at least a rest channel identifier indicating a rest channel of the first network location and the inter-site roaming beacon including at least remote rest channel repeater information identifying a second repeater at a second network location that is currently acting as a rest channel repeater at the second network location. The first repeater may then broadcast the intra-site beacon at the first timing and the inter-site roaming beacon at the second timing.

Abstract: A new group call request is received from a subscriber station at a rest channel repeater at a first network location. Corresponding new group call notifications are then transmitted to each of the other network locations over a wide area network to a current one of the repeaters acting as a rest channel repeater at each of the other network locations. Subsequently, an identity of a traffic channel repeater hosting the new call is received from each of the respective other network locations. An over-the-air notification is transmitted to other subscriber stations at the first network location identifying one of the first rest channel and another available channel as a channel for the new group call. Data received from the first subscriber station is then forwarded to each of the identified traffic channel repeaters at each of the other network locations via the wide area network.

Abstract: Disclosed is a method of automatic establishment of a location-based talk group call with reduced messaging overhead. The initiating device may be a subscriber unit (SU). The SU determines a geographic reference location and generates location data representative of the location. The SU broadcasts a location-based talk group call header including the location data and including a location-based talk group call identifier field set to cause other SUs receiving the call header to receive and output subsequent data associated with the call header responsive to determining that its current geographic location satisfies the location criterion of the call. The location criterion may be fully determined by the initiating SU and specified in the call header, and may take the form of a specified radius that extends from the geographic reference location represented in the call header.

Abstract: A method and apparatus for enabling a radio to track channel timing and support channel scanning A non-leading radio operating on a communications channel, determines a diffusion period during which channel timing is to be propagated from a leading radio to non-leading radios operating on the communications channel. The non-leading radio implements a first scanning pattern during the diffusion period to scan a CT designated channel for a control timing message with a timing signal sent from the leading radio. The first scanning pattern involves scanning the CT designated channel during every other scan interval and scanning non-priority channels and priority channels during scan intervals not used on the CT designated channel.

Abstract: A system and method for interrupting a transmitting device during a call. In the system, calls are transmitted from a first device on a communication channel as a series of channel frames. At predetermined times during the transmission, the transmitting device is configured to drop channel frames, resulting in open channel frame periods where the transmitting device is not transmitting on the communication channel. During these open channel frame periods, the transmitting device is also configured to switch to a receiving mode. Other devices in the system are capable of switching into a transmitting mode during the open channel frame periods and, when applicable, sending an interrupt request on the communication channel to the transmitting device in order to request access to the channel.

Abstract: A system and method for interrupting a transmitting device during a call. In the system, calls are transmitted from a first device on a communication channel as a series of channel frames. At predetermined times during the transmission, the transmitting device is configured to drop channel frames, resulting in open channel frame periods where the transmitting device is not transmitting on the communication channel. During these open channel frame periods, the transmitting device is also configured to switch to a receiving mode. Other devices in the system are capable of switching into a transmitting mode during the open channel frame periods and, when applicable, sending an interrupt request on the communication channel to the transmitting device in order to request access to the channel.

Abstract: A method and apparatus for confirming delivery of group data to a plurality of radio communication devices in a wireless communication system. The wireless communication system includes a plurality of radio communication devices in communication with a sender. In operation, the sender sends group data to the plurality of radio communication devices and further determines a call hang time sufficient to contain a dedicated acknowledgment slot for each of the plurality of radio communication devices. The sender reserves an acknowledgment slot in the determined call hang time for each radio communication device and further sends an acknowledgment polling signal to each radio communication device, where the acknowledgment polling signal identifies the respective acknowledgment slot that is reserved for each radio communication device to acknowledge receipt of the group data. The sender accordingly receives an acknowledgment from the radio communication devices during its respective reserved acknowledgment slot.

Abstract: A method for synchronizing the direct mode TDMA transmission of a set of radios by following a selected radio as the leader includes: receiving, by a radio, a communication from an other radio; identifying, by the radio, a leader according to a leadership election rule using the received communication from the other radio and a current leader information; setting, by the radio, the identified leader as its leader; and synchronizing, by the radio, a time slot boundary with a time slot boundary defined by the leader.

Abstract: A first subscriber unit (SU) operating in a two-way radio frequency (RF) communications system having at least one fixed terminal, one or more channels, and a plurality of subscriber units, generates a first burst of data for transmission to the at least one fixed terminal. The first SU calculates a cyclic redundancy check (CRC) or checksum value over (i) at least a first portion of the first burst of data and (ii) at least a portion of a first private data. The first SU transmits the first burst of data and the calculated CRC/checksum value, but not the first private data, to the at least one fixed terminal. The fixed terminal then calculates its own CRC/checksum over the received burst and its own copy of the first private data, and compares the result with the received CRC/checksum. The fixed terminal authenticates the received burst if the values match.

Abstract: Methods, systems and apparatus are disclosed for using effective radiated transmit power of a base station at a wireless communication device to determine whether the wireless communication device is within uplink transmission range of the base station. The wireless communication device can also use the effective radiated transmit power to adjust transmit power at the wireless communication device and save battery resources. In one implementation, the disclosed embodiments can be applied in a two-way wireless communication system.

Abstract: Disclosed are methods and systems for compressing location data of a radio for over-the-air transmission. A method includes obtaining raw latitude and raw longitude coordinates reflecting a current location of the client device, the raw latitude coordinate represented by x number of bits and the raw longitude coordinate represented by y number of bits. The raw latitude coordinate is truncated by removing n number of most significant bits from the raw latitude coordinate to create a compressed latitude coordinate. The raw longitude coordinate is truncated by removing m number of most significant bits from the raw longitude coordinate to create a compressed longitude coordinate, where m varies as a function of the value of the raw latitude coordinate. The compressed longitude and compressed latitude coordinates are then transmitted to another network device for decompression and use as an indication of the client device's absolute location.

Abstract: Methods, systems and apparatus are disclosed for using effective radiated transmit power of a base station at a wireless communication device to perform an automatic roaming method. In one implementation, the disclosed embodiments can be applied in a two-way wireless communication system.

Abstract: Disclosed are methods and systems for compressing location data of a radio for over-the-air transmission. A method includes obtaining raw latitude and raw longitude coordinates reflecting a current location of the client device, the raw latitude coordinate represented by x number of bits and the raw longitude coordinate represented by y number of bits. The raw latitude coordinate is truncated by removing n number of most significant bits from the raw latitude coordinate to create a compressed latitude coordinate. The raw longitude coordinate is truncated by removing m number of most significant bits from the raw longitude coordinate to create a compressed longitude coordinate, where m varies as a function of the value of the raw latitude coordinate. The compressed longitude and compressed latitude coordinates are then transmitted to another network device for decompression and use as an indication of the client device's absolute location.

Abstract: A method for diffusing channel timing among a plurality of subscriber units operating in TDMA Direct Mode, wherein the method includes: receiving, from a second one of the subscriber units operating in the TDMA Direct Mode, a first message; determining first channel timing from the received message; determining whether the received first channel timing is correct, wherein the determining is based at least on comparing a generation of the first subscriber unit with a generation of the second subscriber unit; when the received first channel timing is correct, starting a random delay; upon expiration of the random delay, transmitting a first forced propagation message to propagate the first channel timing to at least a third one of the subscriber units operating in the TDMA Direct Mode and having a higher generation than the generations of the first and the second subscriber units.

Abstract: A method for synchronizing the direct mode TDMA transmission of a set of radios by following a selected radio as the leader includes: receiving, by a radio, a communication from an other radio; identifying, by the radio, a leader according to a leadership election rule using the received communication from the other radio and a current leader information; setting, by the radio, the identified leader as its leader; and synchronizing, by the radio, a time slot boundary with a time slot boundary defined by the leader.

Abstract: In a peer to peer trunked radio network having a plurality of network locations, each network location includes a plurality of repeaters and a dynamically selected at least temporarily act as a rest channel repeater at each network location. A first repeater at the first network location may determine a first timing at which to broadcast an intra-site beacon and a second timing at which to broadcast an inter-site roaming beacon, the intra-site beacon including at least a rest channel identifier indicating a rest channel of the first network location and the inter-site roaming beacon including at least remote rest channel repeater information identifying a second repeater at a second network location that is currently acting as a rest channel repeater at the second network location. The first repeater may then broadcast the intra-site beacon at the first timing and the inter-site roaming beacon at the second timing.

Abstract: A transmitting device encrypts DMR voice superframes using encryption parameters and sends the encryption parameters in at least one of the voice superframes by: identifying a selected number of bits from a plurality of vocoder frames the voice superframe; replacing each of the identified bits with a corresponding bit of a first encryption parameter; placing at least one encryption parameter in an embedded signaling field of the voice superframe; and transmitting the voice superframe with the encryption parameters to a receiving device. The receiving device extracts the encryption parameters, which can be a key identifier, an algorithm identifier, and an initialization vector for use in decrypting messages from the transmitting device.