COOPERATIVE TRANSMISSION CONTINUOUS TRANSMISSION ENHANCEMENT

A system and method for increasing the efficiency of an avalanche relay scheme is disclosed. The system and method include a plurality of networked nodes communicating in a slot and subslot scheme, with transmissions of a first signal from a first subslot relayed in subsequent subslots. The method and system include transmitting an initial transmission that includes the first signal, and then continuing to transmit at least one of a retransmitted portion of the first signal, or a transmission of an algorithmically related signal based on the first signal. The receiving node combines the first signal with the retransmitted portion of the first signal or the algorithmically related signal to determine if the initial transmission is valid. Upon a determination that the initial transmission is valid, the relay node retransmits the initial transmission in a future subslot.

BACKGROUND

Many network relay systems rely on synchronized time-based schemes that permit the orderly transmission, reception, and retransmission of messages. These schemes often rely on non-data transmitting time-periods that add considerable overhead to each transmission and retransmission. These synchronized time-based schemes are also susceptible to noise. Therefore, it is desirable to provide a system and method that avoids the shortcomings of conventional approaches.

SUMMARY

A method is disclosed. In one or more embodiments, the method includes establishing a multiple access communication scheme among a plurality of network nodes, wherein the multiple access communication scheme utilizes subslots. In one or more embodiments, the method further includes transmitting an initial transmission from an originating node or a retransmitting node in a first subslot to at least one relay node, wherein the initial transmission includes a first signal that is sufficient to convey a message. In some embodiments, the method further continuing to transmit, by the originating node to the at least one relay node, additional signal including at least one of a retransmitted portion of the first signal, a transmission of an algorithmically related signal based on the first signal, or a transmission of the algorithmically related signal based on the message, within the first subslot or a beginning of a subsequent subslot, wherein the additional signal is transmitted by the originating node or retransmitting node past a decision point is used by the at least one relay node to determine whether to transmit a retransmission of the first signal to convey the message in the subsequent subslot or a next subsequent subslot. In one or more embodiments, the method further includes determining by the at least one relay node that it has received the message. In one or more embodiments, the method further includes preparing the retransmission of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal conveying the message by the at least one relay node within a future subslot based upon a determination at the decision point that the at least one relay has received the message, wherein preparing the retransmission includes determining the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, that is coordinated in content between the originating node and the relay nodes transmitting the message. In one or more embodiments, the method further includes transmitting the retransmission of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, in the future subslot, wherein the retransmission is coordinated in time between all the relay nodes transmitting the message.

In some embodiments of the method, transmitting the first signal with the additional signal increases a likelihood of correct reception of the first signal by another node in the subsequent subslot.

In some embodiments of the method, the algorithmically related signal based on the first signal or the algorithmically related signal based on the message, includes error correcting code.

In some embodiments of the method, the retransmitted portion of the first signal is transmitted into the first subslot.

In some embodiments of the method, the retransmitted portion of the first signal is transmitted into the beginning of the subsequent subslot.

In some embodiments of the method, the wherein the algorithmically related signal based on the first signal or the algorithmically related signal based on the message, is transmitted into the first subslot.

In some embodiments of the method, the algorithmically related signal is transmitted into the subsequent subslot.

In some embodiments of the method, a section of the first subslot receiving the retransmitted portion of the first signal, or the algorithmically related signal, corresponds to a guard interval.

In some embodiments, a section of the first subslot receiving the retransmitted portion of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, corresponds to a guard interval.

In some embodiments, wherein a section of the subsequent subslot receiving the retransmitted portion of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, corresponds to a preamble interval.

In some embodiments, the plurality of network nodes is configured to perform an avalanche relay protocol.

In some embodiments, the method further includes partitioning an available communication resource into slots, and the subslots

In some embodiments, the method further includes preparing the retransmission of the first signal by the at least one relay node within the future subslot, based on the determination at the decision point that the at least one relay has not received the message, wherein the at least one relay node does not retransmit the retransmission of the first signal in the subsequent subslot, wherein the at least one relay node retransmits the first signal conveying the message as the retransmission in the first subslot after a successful reception of the message prior to the decision point, wherein the retransmission of the first signal is based on data transmitted past the decision point by the originating node and/or retransmitting nodes. In some embodiments, preparing the retransmission includes continuing to receive additional signal until a next decision point. In some embodiments, preparing the retransmission further includes combining the first signal with at least one of the retransmitted portion of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message. In some embodiments, preparing the retransmission further includes detecting if the message conveyed by the first signal has been correctly received based on a combination of the first signal and the retransmitted portion of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message in prior subslots and up to the decision point. In some embodiments, preparing the retransmission further includes generating the retransmission of the first signal conveying the message by the at least one relay node within the future subslot based upon the determination at the next decision point that the at least one relay has received the message, wherein generating the retransmission includes determining the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, that is coordinated in content between the originating nodes and the relay nodes transmitting the message. In some embodiments, the method further includes transmitting the retransmission of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, in the future subslot, wherein the retransmission is coordinated in time between all relays transmitting the message.

In some embodiments of the method, the method further includes preparing the retransmission further includes continuing to receive additional signal until one or more subsequent decisions points after the next decision point.

In some embodiments of the method, the additional signal is transmitted by all transmitting nodes continuing to transmit during a preamble interval during which at least one node transmits a preamble

In some embodiments of the method, the retransmission of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message further includes additional data that is transmitted past the decision point.

A system is disclosed. In one or more embodiments, the system includes a plurality of network nodes. In one or more embodiments of the system, two or more network nodes includes an antenna, a transmitter, and a receiver. In one or more embodiments of the system, the two or more network nodes further include one or more processors. In one or more embodiments of the system, the two or more network nodes further include a memory with instructions stored upon that are executed by the one or more processors. In one or more embodiments, the instructions include establishing a multiple access communication scheme among the plurality of network nodes, wherein the multiple access communication scheme utilizes subslots. In one or more embodiments, the instructions further include transmitting an initial transmission from an originating node or a retransmitting node in a first subslot to at least one relay node, wherein the initial transmission comprises a first signal that is sufficient to convey a message. In one or more embodiments, the instructions further include continuing to transmit to transmit, by the originating node to the at least one relay node, additional signal comprising at least one of a retransmitted portion of the first signal, a transmission of an algorithmically related signal based on the first signal or a transmission of the algorithmically related signal based on the message, within the first subslot or a beginning of a subsequent subslot, wherein the additional signal is transmitted by the originating node or retransmitting node past a decision point used by the at least one relay node to determine whether to transmit a retransmission of the first signal to convey the message in the subsequent subslot. In one or more embodiments, the system further includes determining by the at least one relay node that the at least one relay node has received the message. In one or more embodiments, the system further includes the retransmission of the first signal conveying the message by the at least one relay node within a future subslot based upon a determination at the decision point that the at least one relay has received the message, wherein preparing the retransmission comprises determining the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, that is coordinated in content between all originating nodes and all relay nodes transmitting the message. In one or more embodiments, the instructions further include transmitting the retransmission of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, in the future subslot, wherein the retransmission is coordinated in time between all relays transmitting the message.

In some embodiments of the system, a combination of the first signal with the retransmitted portion of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related first signal based on the message increases a likelihood of a reception of the first signal by another node.

In some embodiments of the system, the instructions further cause the one or more processor to prepare the retransmission of the first signal by the at least one relay node within the future subslot, based on the determination at the decision point that the at least one relay node has not received the message, wherein the at least one relay node does not retransmit the retransmission of the first signal in the subsequent subslot, wherein the at least one relay node retransmits the first signal conveying the message as the retransmission in the first subslot after a successful reception of the message prior to the decision point, wherein the retransmission is based on data transmitted past the decision point by the originating node and/or retransmitting nodes. In some embodiments, preparing the retransmission comprises continuing to receive additional signal until a next decision point. In some embodiments, preparing the retransmission further comprises combining the first signal with at least one of the retransmitted portion of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message. In some embodiments, preparing the retransmission further comprises detecting if the message conveyed by the first signal has been correctly received based on a combination of the first signal and the retransmitted portion of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, in prior subslots and up to the decision point. In some embodiments, preparing the retransmission further comprises generating the retransmission of the first signal conveying the message by the at least one relay node within the future subslot based upon the determination at the next decision point that the at least one relay has received the message, wherein generating the retransmission comprises determining the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, that is coordinated in content between all originating nodes and all relay nodes transmitting the message. In some embodiments, the instructions further cause the one or more processor to transmit the retransmission of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, in the future subslot, wherein the retransmission is coordinated in time between all relays transmitting the message.

Another method is disclosed. In one or more embodiments, the method includes establishing a multiple access communication scheme among a plurality of network nodes, wherein the multiple access communication scheme utilizes subslots. In one or more embodiments, the method further includes transmitting an initial transmission from an originating node or a retransmitting node in a first subslot to at least one relay node, wherein the initial transmission comprises a first signal that is sufficient to convey a message. In one or more embodiments, the method further includes continuing to transmit, by the originating node to the at least one relay node, additional signal comprising at least one of a retransmitted portion of the first signal, a transmission of an algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, within the first subslot or a beginning of a subsequent subslot, wherein the additional signal is transmitted by the originating node or retransmitting node past a decision point used by the at least one relay node to determine whether to transmit a retransmission of the first signal to convey the message in the subsequent subslot. In one or more embodiments, the method further includes determining by the at least one relay node that the at least one relay node has received the message. In one or more embodiments, the method further includes preparing the retransmission of the first signal by the at least one relay node within a future subslot, based on a determination at the decision point that the at least one relay has not received the message, wherein the at least one relay node does not retransmit the retransmission of the first signal in the subsequent subslot, wherein the at least one relay node retransmits the first signal conveying the message as a retransmission in the first subslot after a successful reception of the message prior to the decision point, wherein the retransmission of the first signal is based on data transmitted past the decision point by the originating node and/or retransmitting nodes. In one or more embodiments, preparing the retransmission includes continuing to receive additional signal until a next decision point. In one or more embodiments, preparing the retransmission further includes combining the first signal with at least one of the retransmitted portion of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message. In one or more embodiments, preparing the retransmission further includes detecting if the message conveyed by the first signal has been correctly received based on a combination of the first signal and the retransmitted portion of the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, in prior subslots and up to the decision point. In one or more embodiments, preparing the retransmission further includes generating a retransmission of the first signal conveying the message by the at least one relay node within the future subslot based upon the determination at the next decision point that the at least one relay has received the message, wherein generating the retransmission of the first signal comprises determining the first signal, the algorithmically related signal based on the first signal, or the algorithmically related signal based on the message, that is coordinated in content between the originating nodes and relay nodes transmitting the message. In one or more embodiments, the method further includes transmitting the retransmission of the first signal, the algorithmically related signal based on the first signal, of the algorithmically related signal based on the message, in the future subslot, wherein the retransmission is coordinated in time between all relays transmitting the message.

In some embodiments of the method, nodes transmitting in the first subslot transmits additional signal in a preamble interval in the subsequent subslot, wherein at least one node that does not transmit in the subsequent subslot transmits a preamble in a preamble interval of a next subslot after the subsequent subslot and retransmits the first signal in the next subslot after the subsequent subslot.

DETAILED DESCRIPTION

A system and method for performing relaying transmissions is disclosed. The system and method utilize a time-diverse, multiple access relay scheme (e.g., a TDMA method using slots, with one or more slots containing subslots), wherein an initial transmission, which includes a first signal conveying a message, is transmitted in a first subslot (e.g., of a first slot) and received by a relay node, which retransmits the first signal, or an algorithmically related signal based on the first signal (e.g., conveying the same message as the first signal and/or including error correcting code) in a subsequent subslot. Each transmission may be received by several relay nodes and subsequently retransmitted in later subslots, enabling all nodes to receive the first signal. A second signal conveying a second message may then be transmitted in a second, or future, slot.

The first signal, or algorithmically related signal based on the first signal, is sufficient to convey a message from one node to another. In that sense, the message may be conveyed via an algorithmically related signal that is based on the message. Additional signals are also transmitted that may be combined with the first signal and/or algorithmically related signal based on the first signal to increase the probability of reception of the message. The additional signals may include signals that convey the message on its own, or may include signals that augment elements of the first signal and/or algorithmically related signal based on the first signal.

In some embodiments, the system and method utilize an avalanche relay protocol, as described in U.S. Pat. No. 4,639,937, entitled “HF avalanche relay communication technique” filed by McRae on Dec. 7, 1983, which is incorporated by reference in its entirety. In particular, the system and method of the current disclosure describe nodes that, having transmitted a first signal within a subslot, may continue to transmit data, such as a portion of already-transmitted first signal, or the algorithmically related signal, which may include error correcting code corresponding to the already-transmitted transmission, within the same subslot, or the beginning of the subsequent subslot. At a specific point in time, processors within nodes receiving the transmission make a decision on whether to be silent or retransmit the message. This decision is based on error detection codes ((e.g., CRC) or other methods which are used to indicate whether the data that the node has detected has been correctly received.

The receiving node may then prepare a retransmission, and transmit the retransmission in a subsequent, or future, subslot. In contrast to traditional subslot-comprising (e.g., avalanche) relay systems which utilize a guard interval within each subslot to prevent interference between previous and subsequent transmissions and allow time for receivers to detect the first signal in time to decide whether to retransmit the first signal or an algorithmically related signal in the transmission interval of the following subslot, and a preamble for synchronization data, the current system and method reduces the number of guard intervals and/or preambles, within each slot, decreasing transmit inactive time and decreasing the probability of a faulty reception by increasing the proportion of time and therefor signal energy devoted to the information bits.

FIG.1is a diagram illustrating a system90that includes multiple nodes100a-g(e.g., network nodes) of a network104, in accordance with one or more embodiments of the disclosure. The network104may be configured as any type of mobile or non-mobile network, any type of wireless or wireline network, and any type of centralized or decentralized (e.g., ad hoc) network. For example, the network104may be configured as a wireless mobile ad hoc network (MANET). The network104may be configured with any type of topography including but not limited to mesh, star, ring, line, tree, bus, and fully connected topologies. For example, the network104may be configured as a MANET with a mesh topology.

The lines connecting each node100a-grepresent lines of communication that are capable between each node, where each node100a-gcan receive and transmit data with at least one other node100a-g. This arrangement allows all nodes100a-gto eventually receive the same data. For example, in an avalanche relay scheme, each node100a-gis capable of receiving data conveying a message within a subslot of a TMDA slot (e.g., the first signal) and transmitting the same message in the next available subslot, with all nodes100a-greceiving the message by the end of the slot (e.g., resulting in a fully connected topology).

The network104includes at least one node100a-gconfigured to transmit a first signal and at least one node100a-gconfigured to relay the first signal. A block diagram of a node100a-gis shown inFIG.2, in accordance with one or more embodiments of the disclosure. One or more nodes100a-gof the network104may contain a transmitter204, a receiver205(e.g., or a transceiver) and an antenna208. The transmitter204, receiver205and the antenna208may be configured to send and receive a diversity signal. For example, the transmitter204and/or receiver205may be configured to perform time-division multiple access (TDMA) based communication. One or more nodes100a-gmay also be configured to utilize spread-spectrum/frequency hopping techniques, and may be configured to operate under other channel access methods including but not limited to frequency-division multiple access (FDMA), code-division multiple access (CDMA), spread spectrum multiple access, space-division multiple access, power-division multiple access (PDMA), packet mode methods, and the like.

The node100a-gmay include a controller240configured to provide processing functionality for the node100a-g. The controller240comprises one or more processors244, a memory248, and a computer interface252. The one or more processors244may include any processor or processing element known in the art. For the purposes of the present disclosure, the term “processor” or “processing element” may be broadly defined to encompass any device having one or more processing or logic elements (e.g., one or more micro-processor devices, one or more application specific integrated circuit (ASIC) devices, one or more field programmable gate arrays (FPGAs), or one or more digital signal processors (DSPs)). In this sense, the one or more processors244may include any device configured to execute algorithms and/or instructions (e.g., program instructions stored in memory248). In one embodiment, the one or more processors244may be embodied as a desktop computer, a flight computer, mainframe computer system, workstation, image computer, parallel processor, networked computer, or any other computer system configured to execute a program configured to operate the node100a-g, as described throughout the present disclosure. Moreover, different subsystems of the node100a-gmay include a processor or logic elements suitable for carrying out at least a portion of the steps described in the present disclosure. Therefore, the above description should not be interpreted as a limitation on the embodiments of the present disclosure but merely as an illustration. In some embodiments, the node100a-gis configured to detect signal quality and/or alter a transmission profile of the communication scheme based on signal quality. Signal quality may include an ability of the node100a-gto transmit/receive a signal and may include the environment for signal transmission. For example, the node100a-gmay be configured to alter the transformation profile of the communication scheme due to interference caused by a lightning storm. Signal quality may also be used in determining whether correct reception has been made by a node100a-g

The memory248can be an example of tangible, computer-readable storage medium that provides storage functionality to store various data and/or program code associated with operation of the controller240and/or other components of the node100a-g, such as software programs and/or code segments, or other data to instruct the controller240and/or other components to perform the functionality described herein. Thus, the memory248can store data, such as a program of instructions for operating the node100a-gor other components. It should be noted that while a single memory248is described, a wide variety of types and combinations of memory248(e.g., tangible, non-transitory memory) can be employed. The memory248can be integral with the controller, can comprise stand-alone memory, or can be a combination of both. Some examples of the memory248can include removable and non-removable memory components, such as a programmable logic device, random-access memory (RAM), read-only memory (ROM), flash memory (e.g., a secure digital (SD) memory card, a mini-SD memory card, and/or a micro-SD memory card), solid-state drive (SSD) memory, magnetic memory, optical memory, universal serial bus (USB) memory devices, hard disk memory, external memory, and so forth.

The communication interface252can be operatively configured to communicate with components of the controller240and other components of the node100a-g. For example, the communication interface252can be configured to retrieve data from the controller240or other components, transmit data for storage in the memory248, retrieve data from storage in the memory248, and so forth. The communication interface252can also be communicatively coupled with controller240and/or system elements to facilitate data transfer between system components.

The network104may be configured to operate in a TDMA scheme300, as illustrated inFIGS.3A-5B, in accordance with one or more embodiments of the disclosure. The TDMA scheme300may be synchronized, with multiple nodes transmitting within an available communication resource (e.g., a time period). For example, the TDMA scheme300may include one or more slots308partitioned into two or more subslots312a-c. Messages, or portions of messages, may be transmitted over the slots308and subslots312a-cin a time orderly fashion, with the messaging repeated (transmissions316a-c) within the different subslots312a-c. Repeating the transmission within a slot308creates a time-diverse signal that may increase the ability of the transmission316a-cto be correctly received. Retransmissions of a first-signal or an algorithmically related signal make this space and time diverse. For example, a transmission may be transmitted by a node100ain a first subslot312a, then received by another node100band retransmitted in a subsequent subslot312b. The transmission and retransmission of a signals within subslots312a-bof a single slot308is a hallmark of an avalanche relay, which is disclosed in U.S. Pat. No. 4,639,937, entitled “HF avalanche relay communication technique” filed by McRae. It should be understood that the TDMA scheme300does not necessarily have rigid slots308. For example, an asynchronous initial transmission can form a first subslot312of a slot308with subsequent retransmissions timed relative to received transmissions in previous subslots312. In some embodiments, the slot can appear asynchronously (e.g., can appear at any time) and is not required to be embedded in a rigid TDMA structure.

An initial transmission316transmitting a first signal318within a traditional single subslot312is demonstrated inFIG.3B, in accordance with one or more embodiments of the disclosure. In this traditional subslot scheme, the initial transmission316aincludes a first signal318(e.g., transmitted during a block of transmission time within the subslot312which includes the message to be sent. The initial transmission316afurther includes a preamble (e.g., transmitted during a preamble interval322) usually organized at the beginning of the subslot312. Data transmitted during the preamble interval322includes timing and synchronizing information that ensures that the TADA receiver can ascertain the presence of the signal and the timing of the first signal318as it is transmitted and/or retransmitted at specific times. The traditional subslot312further makes use of a guard interval324(e.g., or guard time) after the end of the first signal that prevents the transmission216a-cfrom overlapping and allows time for receivers to detect the data contained in the first signal and make a decision (e.g., at a decision point326) on whether to continue to receive or to retransmit the first signal318or algorithmically related signal (e.g., based on the first signal318or the message) in the next subslot. Because the guard interval324is disposed on the end of the subslot312, any transmissions occurring in the guard interval324arrive too late to affect the decision-making that the receiver205will do in the next subslot312. In contrast, the first signal318may be used by the node100a-gin determining if the transmitter204of the node can retransmit the first signal318in the next subslot312b. For example, once the first signal318is received by the receiver205, the node100a-gmay decide 1) whether the first signal318has been correctly received, and 2) whether the first signal318can be retransmitted into a future subslot312.

In embodiments, the initial transmission316may include additional signals320including at least one of a retransmitted portion of the first signal218or an algorithmically related signal (e.g., based on the first signal318or the message) as shown inFIG.3C, in accordance with one or more embodiments of the disclosure. For example, the additional signals320may be transmitted after the first signal318is transmitted. For instance, the additional signals may be transmitted at the end, to the end, or near the end, of the subslot312(e.g., essentially replacing the guard interval324of a traditional subslot312). The additional signals320are used by the receiver205of the node100a-gto improve the likelihood of correctly detecting the information in the next subslot. For example, additional signals320transmitted by a node100a-gin the first subslot312a, may be combined with to the first signal318during the period of the second subslot. Once combined, processors244within the node100a-gdetermine whether the message conveyed by the first signal318has been correctly received and should be retransmitted, the node100a-gcan retransmit the first signal318or an algorithmically related first signal in a third or later subslot312c-n. The steps of receiving additional signals320, combining the signals, and determining that the message has been received are time sensitive. For example, a receiving node100will receive additional signals320up to the decision point326, at which time the received signals will need to be combined and processed so that a determination can be made on whether to prepare to retransmit the message in the next subslot312.

It should be understood that the combining of signals in this disclosure may refer to either the combination of signals directly (e.g., the combination of a first signal318and with additional signals320that contain a retransmitted portion of the first signal318) or to the combination of information derived from the signals. For example, when the first signal and additional signals are comprised of modulated bits, the bits may be detected and the combining step may occur after the detection and be undertaken with bits, rather than signal. The bits may also be represented as soft-decisions and the combination may employ soft decisions. A transmission may also include error detection and correction code. For example, if an error detection and correction code is transmitted and received, the received signal may be combined and detected (e.g., as bits or soft decisions) prior to running the error correction and detection code. In another example, the error correction and detection decoder may operate with bits that are output from independent detections of each of the first signals and additional signals. For clarity, in the latter case, there is no constraint that the modulated bits in the first signal and any retransmitted first signal, or the modulated bits in the additional signal or any retransmitted additional signal, need to be the same as they may be different bits derived from parity equations from a low-rate error detection and correction code operating on the same message.

The combining of signals may be performed by various circuitry within the controller240(e.g., via the one or more processors244), or other node componentry. For example, the combining of signals may be performed by an equalizer integrated within, or separated from, the one or more processors244. Once the equalizer has combined the signal, the node may then determine whether the message has been correctly received based on the combined signal, and the combined signal may be retransmitted in a subsequent subslot312based on whether the determination of a correctly received combined signal comes before or after a specific decision point326.

The retransmitted portion of the first signal318included within the additional signal320may include any portion, or any size of portion, of the first signal318. For example, the retransmitted portion of the first signal may include roughly the first third of the first signal318. The algorithmically related signal, based on the first signal318or the message, may include any data related to the first signal including but not limited to error correcting code, as detailed herein.

The additional signal320may be transmitted by the transmitter204after a short delay after transmitting the first signal318(e.g., the subslot312retaining a small guard interval324), or may be transmitted without break from the transmitter204(e.g., the transmitter204can be keyed-on the whole time during the transmission of the additional signal320) Transmitting to the end of a subslot312is possible for all subslots312within the slot308, however in some cases, transmission may not occur to the end of the last subslot312c, as the guard interval324may be required between slots308=.

FIG.3Ddemonstrates a subslot312b, configured with a transmission316athat continues from subslot312ainto subslot312b, and a transmission316bthat initiates and ends in subslot312b, in accordance with one or more embodiments of the disclosure. The transmission316includes an extended additional signal320that is transmitted through the boundary of the two subslots. The preamble interval322is reduced and/or omitted from subslot312b. As above, the additional signal320may be transmitted by the transmitter204after a short delay after transmitting the first signal318(e.g., the subslot312retaining a small guard interval324or preamble interval322), or may be transmitted without break from the transmitter204. Transmitting a transmission316ainto the beginning of a subsequent subslot312bis possible for all subslots312within the slot308with the exception of the first subslot312a, as an initial preamble interval322is required at the beginning of any transmission, either by an originating node, or a retransmitting node. After the first signal318of the second transmission316is transmitted within the second subslot312b, the end of the subslot may be reserved for a guard interval342(e.g., as shown inFIG.3D), or may have additional signal320transmitted as shown inFIG.3E. Due to a constraint that the signal from two transmitters204transmitting at or very near the same time must be the same, nodes100a-gthat continue to transmit additional signal320must ensure that the same signal is transmitted by all with the additional signal320essentially an extension of the first signal, that replaces the guard interval324and/or preamble interval322and may serve to increase the likelihood of the first signal318being correctly detected by another node100a-gin a subsequent slot.

A traditional transmission profile328of the TDMA scheme300showing three slots308a-c, each with three subslots312a-c, is shown inFIG.3Fin accordance with one or more embodiments of the disclosure. Each node100a-gis capable of originating and relaying a transmission316a-c, and each slot308a-cis used to send a signal (e.g., the first signal318in the first slot308a, a second signal332in the second slot308b, and a third signal336in the third slot308c) that is transmitted or retransmitted via the three subslots312a-c, which act to ensure that each targeted nodes308a-ghave correctly received the first signal318, the second signal332, and the third signal336. For example, In the first subslot312aof the first slot308a, a node100atransmits the transmission316afor the first time (e.g., the initial transmission). The transmission316ais received by three nodes100b-dand retransmitted (e.g., transmission316b) in the second subslot312bof the first slot308a. The node100amay also retransmit the transmission316bas well.

It is noted that the first signal318, once transmitted by the initiating node100a, retains the status as the first signal318after retransmission through another node100a-gwithin the same slot308a, as the message encoded by the first signal318adoes not change. It is also noted that a first signal that may be encoded (e.g., to produce an algorithmically related signal) by a node100a-eand transmitted and may still referred to as a first signal318or may be referred to as an algorithmically related signal (i.e., the first signal retains the same message, whether or not a retransmission of the first signal has been encoded). The algorithmically related signal may also include, or may only include, error correcting code that corresponds to the first signal. For example, in slot308a, the first signal318and all retransmitted signals and algorithmically related signals in slot308amay contain the same message. In the interest of clarity, a subsequent signal transmitted by an initiating node that contains a message different that the first signal is referred to as a second signal332or third signal336.

The original transmission and subsequent retransmissions shown in slot308ais similarly performed in slot308b,308c, and may include messages and signals derived from those messages that are identical to, or different than, first signals318transmitted in slot308a. For example, In the first subslot312aof the second slot308b, node100dis acting as the originating node and transmits the transmission316a, in the first subslot312aof slot308b. Nodes100a-ereceive the transmission and transmit or retransmit into the second subslot312bof the second slot308b. Nodes100a-freceive the transmission316band transmit or retransmit into the third subslot312cof the second slot. In slot308c, node100ginitiates the transmission316ain subslot312a, which is then transmitted and retransmitted in subslots312b-c. Retransmitting transmissions316a-cinto subslots312a-ccreates time-diverse signals that increase the ability of a single node100to competently receive the transmission316a-c.

FIG.4Adiscloses a transmission profile402for the TDMA scheme300with transmissions316a-bthat extend to the end of the subslot312a-bas shown inFIG.3C, in accordance with one or more embodiments of the disclosure. The subslots312a-cinclude first signals318a-cwhich may or may not be the same signal, but all convey the same message (e.g., first signal318cis a retransmission of the message and algorithmically related to first signal318b, which is a retransmission of the message and algorithmically related to first signal318a), additional signals320a-btransmitted in the first two subslots312a-b, with subslot312cretaining a guard interval.

Guard intervals324represents a substantial overhead relative to the portion of the subslot312dedicated to transmitting data (e.g., the first signal318). The additional signals320a-bcontaining the retransmitted portions of the first signal318or an algorithmically related signal, which may include error correction code (e.g., parity bits) permit each node100a-eto perform a quality check on each transmission316a-cas carrying additional data or parity bits in these intervals may improve the likelihood of success in subsequent decoding cycles. For example, and in embodiments, cyclic redundancy check (CRC) code is included within the first signal318a-c, for which the node100receiving the first signal318then makes a decision based on the CRC code whether the message has been received. If the CRC fails, the redundant additional signals transmitted in subsequent subslots312within the slot308will increase the likelihood of subsequent CRCs passing. Data for error checking may further include any type of data for any type of error correction or error correction schemes including but not limited to minimum distance coding, repetition codes, checksums, hash functions, and forward error correction and may include signal quality indications in the determination of whether errors are present.

FIG.4Bdemonstrates an expanded transmission profile404of a TDMA scheme300where transmissions316a-bare transmitted as shown inFIG.4A, in accordance with one or more embodiments of the disclosure. In each slot308a-c, the first subslot312aand the second subslot312btransmit additional signal320, while the last subslot may retain a guard interval324. The data replacing the guard interval324in subslots312a-bcan substantially increase transmission efficiencies. For example, where a guard interval324occupies approximately half the duration in a subslot312as the original data carrying signal, 50% more data carrying signal becomes available, which may be used to reduce code rate and improve the likelihood of correct reception. This approach is valid for both equalized signals requiring positive signal-to-noise ratios for detection and for spread spectrum signals in negative signal-to-noise schemes.

As shown inFIG.4Aeach subslot comprises a decision point326a-cwherein a node100a-gmust make a decision on whether the node100a-ghas a valid reception of the first signal318and can retransmit the first signal318into a subsequent, or future, subslot312. For example, if a node100a-gdecides that the received first signal318is valid (e.g., at decision point326a), the node100a-gmay then transmit the first signal318in the subsequent subslot312. In another example, if a node100adecides at decision point326athat the received first signal318not valid (e.g., containing errors), the node100amay decide at decision point326anot to retransmit the first signal318in the next subslot312band may instead continue to receive and use both the addition signal320aand the next subslot312bfor gathering additional information to improve the detection of the first signal318, wherein the node1003receives additional signal320afrom subslot312atogether with a retransmitted first signal318bto perform the detection. The node100athen combines the received first signals318aand318bwith the additional signal320ato make a decision at the next decision point326b. If the node100a-gdetermines after the combination of signals and analysis of the signals that the message conveyed by the first signal318has been correctly received, the node100a-gmay then decide (e.g., at the next decision point326b) to transmit the first signal318at the next available subslot312c. It should be understood that a node100a-greceiving a first transmission316awithin a first subslot312aof a slot308cannot combine the received signal with additional signal320, as there is no previously transmitted additional signal320that can be combined with the received signal.

The use of previous first signals318aand additional signals320ato influence the reception of the first signal318by a downstream node100can be shown by the originating node100dand relay node100etransmitting the second signal332within slot308binFIG.4B. For example, originating node100dinitially transmits a (first) second signal332athat is not successfully detected by node100e, and particularly node100ecannot discern second signal332aas valid at decision point326d. For this reason, node100eis silent during the second subslot312bof the slot308b. Instead, node100ekeeps listening for signal, and receives additional signal320aand the (second) second signal332b. This time, at or before decision point326e, node100ehas combined the signals from the second signals332a-band the additional signals320a(e.g., as indicated by arrows408, has determined that the second signal received is valid, and transmits the second signal332. In this manner, a node100enot successfully receiving a signal in a first subslot312amay be silent in the second subslot312b, may combine data received in the first subslot312aand the second subslot312b, and may transmit a retransmission based on the combination of data received in the first subslot312aand the second subslot312bin the third subslot312c. It should be understood that the first subslot312amay be configured as the initial subslot312(e.g., the first subslot312in the slot308), or may be configured as the first subslot312that a retransmission is transmitted by a node100. In this manner, the originating node may also be considered to be either the first transmitting node100ain the slot308, or as a node100that transmits a first signal318that is received by another slot308.

In contrast to node100e, node100fis successful in receiving the second signal332ain the first subslot312aof the second slot308b, as shown by node100fretransmitting the second signal332aas second signal332bin subslot312b. As discussed above, retransmission of the second signal332arequires that the node make the decision to retransmit by decision point326d. Node100fthen retransmits into subslot312cthe second signal332c. In this example, both nodes100eand nodes100fhave the same potential to receive the second signal332afrom node100d. Although node100eis not as successful as node100fin immediately picking up the second signal332aand retransmitting in subslot312b, node100eis capable of eventually retransmitting in subslot312cdue to the combining of received second signal332bwith additional signal320a.

It should be understood that the first signal318and additional signal320transmitted at the same time or nearly the same time by nodes100a-gwithin the network104must be common to each node. For example, if all nodes100a-eare transmitting, then all nodes100a-emust transmit the same first signal318and/or the same additional signal in the subsequent subslot. In another example, if all but one node100a-ftransmits a first signal318, while a single node100g, having not received a valid first signal318decides to use the additional signal320to evaluate and/or repair the first signal318, then that signal node100gmay stay quiet (e.g., not transmit) during the subsequent subslot, while the other nodes100a-fare transmitting, and on the next subslot after the subsequent subslot312, may reinitiate transmitting the first signal318. The commonality of transmitted signals also pertains to signals in the preamble for as long as additional signals320are not transmitted during the preamble interval322. In some embodiments, the retransmission of the first signal318is coordinated between transmitting nodes100. For example, the retransmission of the first signal318by retransmitting nodes100is coordinated in time and content (e.g., all nodes retransmit the same data at the same time).

FIG.5Adiscloses a transmission profile502for the TDMA scheme300with transmissions316a-bthat extend through the end of the subslots312a-binto the beginning of subslots b-c, as shown inFIG.3D, in accordance with one or more embodiments of the disclosure. For example, additional signal320afrom the first transmission316aextends from the end of the first subslot312ainto the beginning of the second subslot312b, with the second subslot configured with a reduced or omitted preamble interval322. In another example, additional signal320bfrom the second transmission extends from the end of the second subslot312binto the beginning of the third subslot312c, with the third subslot configured with a reduced or omitted preamble. The first subslot312astill retains a preamble. As with the reduction of the guard interval324, the addition of additional signal320into the space normally given to the preamble interval322may also increase the performance of the transmission316, with each node sending and receiving additional signals (e.g., retransmitted portions of the first signal or algorithmically related signals) that can be used to detect and/or repair invalid first signals318.

FIG.5Bdemonstrates an expanded transmission profile508of a TDMA scheme300where transmissions316a-bare transmitted as shown inFIG.5A, in accordance with one or more embodiments of the disclosure. The preamble interval322of the subslots312b-cof the transmission profile508are reduced or omitted for nodes that are continuing to transmit the same message from a previous subslot, as well the guard intervals324of subslots312a-b, with additional signal320transmitted during these times in many of the nodes100a-g. In this instance, nodes transmitting for the first time will not be sending the same signal as nodes that have transmitted in a previous subslot and are continuing to transmit during the interval that new transmitters begin a transmission with a preamble. As described above, the reduced/omitted preamble interval322and/or guard interval can substantially increase transmission efficiencies, as the preamble interval322may represent a substantial overhead relative to the first signal318. For example, when a signal that can be detected in the presence of strong noise and interferers is used to transmit data (e.g., such as a Walsh coded modulation detected with a rake receiver) better performance can be obtained by having each node100a-gthat is in possession of the information being sent in the current subslot312continue to transmit during the period normally reserved for the guard interval324and preamble interval322. For example, and as indicated inFIG.5A, where the additional signal320occupies the same proportion of the subslot312as the first signal318, the use of the preamble interval322and guard interval324for transmitting data has the effect of doubling the data carrying signal available in all subslots312after the initial transmission, thereby improving the likelihood of the first signal318being received correctly.

It should be noted for systems running the TDMA scheme as shown inFIG.5A-B, if only the nodes100transmitting in a subsequent subslot312will be the same nodes100transmitting in the next subslot312after the subsequent subslot312, then all transmitting nodes will transmit the same additional signal320during the preamble interval322of the subsequent subslot. However, if a node100begins transmitting in the next subslot after the subsequent subslot312(e.g., that was not transmitting in the subsequent subslot312) that node100will transmit a preamble in the preamble interval322, as all nodes100initiating a transmission are expected to transmit a preamble. This would indicate that a preamble interval322may include both nodes100transmitting additional signal320and nodes100transmitting preamble data at the same time. However, and as discussed below, the simultaneous transmission of differing signals may not be problematic.

As noted herein, a node100a-gthat had been synchronized on the initial transmission316(e.g., at the beginning of subslot312a) can continue detecting data from that transmission as it continues into the second subslot312b. Additional retransmitting devices using the same spreading code for that data, for which the transmissions316are synchronized to within the multipath delay spread capability of the receiver, can be detected by the receiver, with additional tines added to the rake receiver to take advantage of the additional multipath signals. For example, nodes100a-gmay include a preamble in their first retransmission, employing a spreading code other than the code used by the data, which facilitates detection and synchronization by nodes100that did not receive the initial transmission316a. For nodes100already synchronized, the preamble interval322encoded with a different spreading code would effectively be an additional source of noise in the rake receiver. Unless the preamble signal is substantially stronger than the signal that the receiver is synchronized to (e.g., depending on the spreading gain) the receiver205will continue to track and receive the ongoing transmission316in the presence of the preamble, and will benefit from additional signal components once the new signal transitions to a common signal and spreading code for data. In the case where the preamble interval322is received by an already synchronized node100a-gis sufficiently strong as to disrupt the ongoing reception, it is likely that the data to follow would also likely be received at a high enough signal-to-noise ratio as to successfully complete the data transmission.

FIG.6is a block diagram illustrating a method600for creating a multiple access communication scheme that utilizes additional signal320for increasing the robustness of transmitting a first signal318, in accordance with one or more embodiments of the disclosure. The method600may be utilized during any network communication event and such as in high signal-to-noise environments, including during adversarial jamming episodes or the presence of other interfering signals.

In some embodiments, the method600includes a step604of establishing a multiple access communication scheme (e.g., a TDMA scheme300) among the plurality of network nodes100a-g. For example, the network104may be created from a plurality of nodes100a-gcapable of receiving a diversity signal as described herein.

In some embodiments, the method600further includes a step608of partitioning an available communication resource into slots308and subslots312. For example, the communication resource (e.g., time) may be organized similarly to the transmission profiles328,402,502as described herein, with slots308, and subslots312. In particular, the transmission profile328,402,502may represent an avalanche relay scheme as described herein.

In some embodiments, the method600further includes a step612of transmitting an initial transmission316afrom an originating node100ain an initial subslot312ato a relay node100b-g, wherein the initial transmission includes a first signal. For example, the initial transmission316amay include a preamble transmitted in the preamble interval322followed by the first signal318.

In some embodiments, the method600further includes a step616of continuing to transmit by the originating node to the relay node additional signal320that includes at least one of a retransmitted portion of the first signal, or a transmission of the algorithmically related signal based on the first signal, within the first subslot312a(e.g., or initial subslot) or a beginning of the subsequent subslot312b. This continuation of the transmission316amay include transmitting at the end, to the end, or toward the end, of the initial subslot312a. For example, the transmission316amay transmit to the end of the subslot312a, omitting the guard interval. The continuation of the transmission316athat includes the additional signal320may also continue into to the subsequent subslot312b. For example, the additional signal320extending into the subsequent subslot312bmay occupy the time usually taken up by the preamble, with the subsequent transmission316bhaving the preamble reduced or omitted.

It should be understood that a transmission316may pass-through any number of subslots312. For example, the transmission316amay pass-though the initial subslot312ato subslot312c. In another example, the transmission316may pass through two subslots312, may pass through three subslots312, or pass through four or more subslots312. The transmission316may also begin at any subslot312within the slot308. For example, the transmission316may initiate at the second subslot312bor at the third subslot312c. Similarly, the originating node100may be configured as any node100that initiates a transmission316that is received by a relay node100. For example, and as shown inFIG.4B, the originating node may be the initial transmitting node in each slot308a-c(e.g., nodes100a,100d, and100g, respectively). The nodes may also include other nodes100that initiate transmission after the first subslot, and are capable of relaying the transmission316to another relay node100(e.g., nodes100b,100c, and100din slot308aofFIG.4B.). In this manner, a node100may both act as a relay node, receiving a transmission316from an originating node, and act as an originating node100transmitting to a relay node.

It should be understood that the configuration of the TDMA scheme300to include time for additional signal320that occupies time traditionally used for preamble intervals322and/or guard intervals324may be a default configuration that is set up when the TDMA scheme300is established. In some embodiments, the TDMA scheme300is set up as a traditional transmission profile328, and then changes to reduced or omitted preamble intervals322and/or guard intervals324. For example, the TDMA scheme300may be altered to have both omitted preamble intervals322and guard intervals322in the middle subslots (e.g., not including the first subslot or last subslot), allowing the transmitter204to remain keyed-on for long periods. The setup and changing of transmission profiles may be performed locally or globally via the one or more nodes100a-g, and may involve node componentry including but not limited to the controller240.

In some embodiments, the method600includes a step620of preparing a retransmission (e.g., transmission316b) of the first signal318by the relay node100b-gwithin a future subslot312b, wherein preparing the retransmission comprises combining the first signal318with at least one of the retransmitted portion of the first signal318or the algorithmically related signal (e.g., additional signal320), detecting if the first signal has been received based on the combination of the first signal and the retransmitted portion of the first signal or the algorithmically related signal; and including a signal conveying the same message as the detected first signal in the retransmission. The combination of the first signal318with the retransmitted portion of the first signal318or the algorithmically related signal (e.g., which may contain error correcting code) may be performed by the controller240or other processing componentry within the node. If the comparison or combination indicates that a valid received first signal318has been detected, the node100a, having received the initial transmission316awill include the signal conveying the same message as the detected first signal in the retransmission, and transmit this into a future subslot312(e.g., the next available subslot312) as noted in step624of the method600.

The decision of which subslot312the receiving node100is to retransmit the first signal318depends on the ability of the node100to detect a valid first signal318and/or repair an invalid reception of a first signal318. For example, and as shown inFIG.4B, if the node100areceives a first signal318and confirms that the first signal318is valid early enough (e.g., at decision point326a), the received first signal318may be transmitted in the next subslot312b. However, if the received first signal318appears to be invalid, the node100awill not transmit in the next subslot312band will instead use that time to carry out the comparison/error correction of the first signal318through use of the received additional signal320. If the comparison/error correction is able to correctly detect the message quickly enough in the next subslot312(e.g., at or before the next decision point326b, the node100awill then transmit the first signal318in the next available subslot312c.