Abstract: An approach for transmitting and receiving Link 16 messages for long ranges and includes a Link 16 terrestrial transmitter, a Link 16 satellite receiver including an antenna, and a controller. The approach aligns the antenna to the Link 16 terrestrial transmitter to determine a minimum distance to an area of interest of the Link 16 terrestrial transmitter, thereby estimating a range of a link from the Link 16 terrestrial transmitter to the Link 16 satellite receiver. From the range, calculating the message propagation time. Providing a second, shifted, time slot at the Link 16 satellite, shifted by the message propagation time. Processing the signal from the Link 16 terrestrial transmitter in the second, shifted, time slot to produce a message from the Link 16 terrestrial transmitter, and presenting the message to a host.

Abstract: A method of transmitting and receiving a plurality of Link 16 messages on a single subnet in a single timeslot includes a transmitting terminal packaging the Link 16 messages into an envelope enhanced throughput message (envelope LET message) and transmitting the envelope LET message to a receiving terminal, followed by the receiving terminal unpacking the Link 16 messages from the envelope LET message, restoring them to their original form, and presenting them to a host. Modification of the host is not required. The Link 16 messages can be relayed messages, and the transmitting terminal can be a relay terminal. The Link 16 messages can be concatenated within the envelope LET message, or another lossless packaging algorithm such as lossless compression can be applied. The terminals can be JTRS terminals, the Link 16 messages can be 115 kbps messages, and the envelope LET message can be a 2 Mbps LET message.

Abstract: A method of transmitting and receiving a plurality of Link 16 messages on a single subnet in a single timeslot includes a transmitting terminal packaging the Link 16 messages into an envelope enhanced throughput message (envelope LET message) and transmitting the envelope LET message to a receiving terminal, followed by the receiving terminal unpacking the Link 16 messages from the envelope LET message, restoring them to their original form, and presenting them to a host. Modification of the host is not required. The Link 16 messages can be relayed messages, and the transmitting terminal can be a relay terminal. The Link 16 messages can be concatenated within the envelope LET message, or another lossless packaging algorithm such as lossless compression can be applied. The terminals can be JTRS terminals, the Link 16 messages can be 115 kbps messages, and the envelope LET message can be a 2 Mbps LET message.

Abstract: A secure wireless transceiver, such as a link 16 transceiver, receives signals using an antenna array having an SOC associated with each antenna element in the array. The SOC's digitize and channelize received data for transmission to a message nulling system that mitigates jamming. The antenna array can be conformal, and can replace an existing Link 16 blade. The disclosed transceiver can be a modified CMN-4 transceiver with digitizing and channelizing moved to the SoC's, and replaced by the nulling system. The transceiver uses applicable TRANSEC information to assign received data to the logical Link 16 channels before nulling, and embodiments apply nulling only to channels of interest, thereby improving the nulling and reducing side lobes. Embodiments distinguish between desired and unwanted signals based on known Link 16 signal features and/or situational awareness, rather than signal amplitudes, thereby enabling nulling of even weak jamming signals.

Abstract: An auto-ICAS compliant system and method of avoiding collisions between aircraft linked by a Link 16 network comprises establishing an ICAS datalink between aircraft less than 10 nautical miles apart. Datalink messages generated and processed by ICAS datalink modules are transmitted and received by Link 16 receivers rather than dedicated ICAS transceivers. The datalink messages are embedded within the propagation delay portions of Link 16 timeslots and exchanged among up to 10 nearby aircraft at a data rate of up to 20 Hz each. Because each Link 16 timeslot can contain a Link 16 message and two 768-bit ICAS datalink messages, conventional Link 16 communication is not impeded. Datalink messages can be software encrypted. Link 16 messages can be encoded using an enhanced throughput Link 16 protocol that includes fewer preamble pulses and/or eliminates STN information. Embedded datalink messages can be transmitted at 1 Watt by a MIDS-JTRS CMN4.

Abstract: An auto-ICAS compliant system and method of avoiding collisions between aircraft linked by a Link 16 network comprises establishing an ICAS datalink between aircraft less than 10 nautical miles apart. Datalink messages generated and processed by ICAS datalink modules are transmitted and received by Link 16 receivers rather than dedicated ICAS transceivers. The datalink messages are embedded within the propagation delay portions of Link 16 timeslots and exchanged among up to 10 nearby aircraft at a data rate of up to 20 Hz each. Because each Link 16 timeslot can contain a Link 16 message and two 768-bit ICAS datalink messages, conventional Link 16 communication is not impeded. Datalink messages can be software encrypted. Link 16 messages can be encoded using an enhanced throughput Link 16 protocol that includes fewer preamble pulses and/or eliminates STN information. Embedded datalink messages can be transmitted at 1 Watt by a MIDS-JTRS CMN4.

Abstract: A wireless receiver and method of wireless communication determines levels of noise, including interference, in communication channels without need of calibration. A digital test signal is digitally added to digitized noise, and a signal-to-noise-and-interference (SNIR) value is determined from a resulting bit error rate and/or message error rate. The level of noise is then determined from the SNIR. The amplitude of the digital test signal is adjusted to cause the SNIR to be sensitive to the noise level, which can require an SNIR between 1 dB and 10 dB. The system can include a digital test signal generator, or the digital test signal can be stored in a memory. The system can further include a channelizer, demodulator, data correlator, decryptor, and message assembler. Noise and interference level determinations can be used to select an optimal communication channel, and to adjust a transmission power and/or rate to suitable values.

Abstract: A secure wireless transceiver, such as a link 16 transceiver, receives signals using an antenna array having an SOC associated with each antenna element in the array. The SOC's digitize and channelize received data for transmission to a message nulling system that mitigates jamming. The antenna array can be conformal, and can replace an existing Link 16 blade. The disclosed transceiver can be a modified CMN-4 transceiver with digitizing and channelizing moved to the SoC's, and replaced by the nulling system. The transceiver uses applicable TRANSEC information to assign received data to the logical Link 16 channels before nulling, and embodiments apply nulling only to channels of interest, thereby improving the nulling and reducing side lobes. Embodiments distinguish between desired and unwanted signals based on known Link 16 signal features and/or situational awareness, rather than signal amplitudes, thereby enabling nulling of even weak jamming signals.

Abstract: A method is disclosed for minimizing latency for high priority messages without sacrificing subnet bandwidth in a wireless, multiple access network such as Link 16. Nodes are able to simultaneously receive messages on at least two subnets, one of which is designated as a low latency (“LL”) subnet that transmits messages immediately on a contention access basis. A message acknowledgement protocol can be implemented and high priority messages that fail due to collisions or other reasons can be retransmitted. Jitter can be used to detect collisions. Embodiments include a plurality of “standard” and/or LL subnets designated for messages of varied urgency. High priority messages can reserve an acknowledgement timeslot for use only by the message recipient. Link 16 embodiments implement CMN-4, whereby the LL subnet is one of four subnets monitored by each node. Link 16 latencies in the LL network can be limited to less than 40 msec.

Abstract: A method for mitigating the effect of a localized jamming attack on a secure, tactical wireless network implements a dynamic relay assignment (“DRA”) approach, whereby nodes are dynamically assigned to relay communications to “disadvantaged” nodes that are subject to the attack, the relay nodes being selected based on their communication reliability and their proximity to the disadvantaged nodes. In embodiments, the nodes share with each other performance statistics and, in embodiments, measured local noise levels. In various embodiments, each node provides data to a “strategy optimizer” which then dynamically makes relay assignments. In Link-16 embodiments support for a “DRA” relay mode is added, and the communication protocol is extended to support the required exchange of communication quality and local noise information via PPLI messages.

Abstract: An unattended apparatus and method for isolating and relaying secure communications under adverse circumstances without awareness of encryption keys uses known and/or inferred characteristics of received transmissions to identify, isolate, and retransmit only friendly communications without decryption or re-encryption, and in embodiments also without awareness of applicable TRANSEC algorithms and keys. A channelizer digitizes energy received within a bandwidth of interest, which is then analyzed to detect chip timing, identify and demodulate pulses, and assemble secure messages for retransmission. In embodiments, the retransmissions use the original frequencies and TRANSEC parameters, and/or otherwise adhere to applicable TRANSEC and MSEC constraints so that the relayed messages are accepted by intended recipients. Embodiments provide interoperability with existing secure communications such as Link 16 and CDL.

Abstract: A method is disclosed for minimizing latency for high priority messages without sacrificing subnet bandwidth in a wireless, multiple access network such as Link 16. Nodes are able to simultaneously receive messages on at least two subnets, one of which is designated as a low latency (“LL”) subnet that transmits messages immediately on a contention access basis. A message acknowledgement protocol can be implemented and high priority messages that fail due to collisions or other reasons can be retransmitted. Jitter can be used to detect collisions. Embodiments include a plurality of “standard” and/or LL subnets designated for messages of varied urgency. High priority messages can reserve an acknowledgement timeslot for use only by the message recipient. Link 16 embodiments implement CMN-4, whereby the LL subnet is one of four subnets monitored by each node. Link 16 latencies in the LL network can be limited to less than 40 msec.

Abstract: A method for mitigating the effect of a localized jamming attack on a secure, tactical wireless network implements a dynamic relay assignment (“DRA”) approach, whereby nodes are dynamically assigned to relay communications to “disadvantaged” nodes that are subject to the attack, the relay nodes being selected based on their communication reliability and their proximity to the disadvantaged nodes. In embodiments, the nodes share with each other performance statistics and, in embodiments, measured local noise levels. In various embodiments, each node provides data to a “strategy optimizer” which then dynamically makes relay assignments. In Link-16 embodiments support for a “DRA” relay mode is added, and the communication protocol is extended to support the required exchange of communication quality and local noise information via PPLI messages.

Abstract: A method for reducing self-interference in a wireless network, such as a Link 16 network, while maintaining simultaneous multiple access takes advantage of the physical proximity of nodes in a localized subnetwork, such as a fighter-to-fighter subnetwork in a flight wing, by actively reducing the transmit powers used for subnet messages between the nodes. Calibration messages such as Precise Participant Location and Identification (PPLI) messages are exchanged between all of the nodes of the localized subnetwork, from which each node determines the identities, transmit powers, noise levels, and SNRs of all of the other nodes. The node then determines a link margin for other nodes, and sets its transmit power to a “safe” level for the subnetwork according to the lowest link margin.

Abstract: A method for implementing interference mitigation in wireless network such as a Link 16 network does not require interference recognition and does not degrade signal detection even in the absence of interference. An unmitigated correlation score is obtained by correlating received, unmitigated preamble symbols with expected symbols. At least one of the input signals is also correlated after mitigation to obtain a mitigated signal. A mitigated correlation sore is obtained from the mitigated signals, and a mixed correlation score is obtained by combining mitigated and unmitigated signals. A signal is detected if any of the correlation scores exceeds a corresponding threshold. Embodiments use the unmitigated correlation for subsequent message time of arrival determination if the unmitigated correlation score is above its detection threshold. In embodiments, mitigation is applied to only one of the message frequencies.

Abstract: A process for allowing a Concurrent Multi-Netting (CMN-4) equipped Link 16 terminal to enter an active network. After an initial entry command is entered at the terminal at a given current time at the terminal, a number of time slots are identified in which multiple receivers at the terminal have an opportunity to detect an initial entry message (IEM) after the given current time. Each of the receivers is set to detect an IEM during a different one of the identified time slots. When an IEM is first detected by one of the receivers, the current time at the terminal is reset based on the time slot in which the IEM was detected.

Abstract: A method for reducing self-interference in a wireless network, such as a Link 16 network, while maintaining simultaneous multiple access takes advantage of the physical proximity of nodes in a localized subnetwork, such as a fighter-to-fighter subnetwork in a flight wing, by actively reducing the transmit powers used for subnet messages between the nodes. Calibration messages such as Precise Participant Location and Identification (PPLI) messages are exchanged between all of the nodes of the localized subnetwork, from which each node determines the identities, transmit powers, noise levels, and SNRs of all of the other nodes. The node then determines a link margin for other nodes, and sets its transmit power to a “safe” level for the subnetwork according to the lowest link margin.

Abstract: A process for allowing a CMN-4 equipped Link 16 terminal to enter an active network. After an initial entry command is entered at the terminal at a given current time at the terminal, a number of time slots are identified in which multiple receivers at the terminal have an opportunity to detect an initial entry message (lEM) after the given current time. Each of the receivers is set to detect an lEM during a different one of the identified time slots. When an lEM is first detected by one of the receivers, the current time at the terminal is reset based on the time slot in which the I EM was detected.