STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

FIELD OF THE INVENTION

The present invention relates generally to digital signal processing, with particular emphasis on machines wirelessly communicating with each other (“machine to machine” or “M2M” intercommunication) in noisy, crowded, multiple-use and multiple-overlap environments. A majority of this wireless intercommunication may occur with indirect, remote, or otherwise removed human oversight focusing on the network and specific communications rather than implementing and effecting each, or even the majority, of such, as part of a broader intercommunication background of multiple networks of machines comprising what has been called “the internet of things” or IoT. The environment for such wireless intercommunication may be ‘noisy’ as there may be multiple, chaotic networks operating with different standards and disparate organization, often transmitting highly bursty, asymmetric traffic from many different sources. Blind linear signal separating secure digital processing methods can be used to provide physically secure wireless M2M intercommunications in such environments, without direct human management, and in a manner that is robust, efficient, and interference-resistant.

Signal generation for message and addressing content (respectively, the ‘data’ containing the information to be communicated and ‘metadata’ describing the sourcing, routing, and receiver for the message being communicated) is no more to be confused with the specific signals forming the message itself, than the process of combining letters and words of a language into a message and delivering it to a recipient, are with formation and delivery of meaning that that message conveys.

BACKGROUND OF THE INVENTION

Machine-to-machine (M2M) networks comprise a thick mesh of tiered hardware forming the skeleton and body of a communications network, incorporating as desired sensor-and-reporting elements, which effectively comprise a ‘nervous system’. Avoiding the time, expense, and effort of physically installing, maintaining, and most particularly adapting wired intercommunication linkages requires that the elements use wireless signals in any, or any set, of electromagnetic spectrum bands.

For any wireless network, providing feedback for regular, directed, and emergency reporting processes all are useful to its continuous operation (particularly when under stress or upon experiencing a failure, whether point, localized, or central, with recovery desired both ‘as soon, and as safe, as possible’ or ‘AS, AAS, AP’).

At the ‘edges’ of the wireless network, every nodal point (home, building, or mobile station) may be a Signaling Machine (SM). Any finite number of Signaling Machines can be aggregated to a lesser order set of Data Aggregation Points (DAP's) each of which serving as an intermediate network distribution point to provide a set of delivery paths with their own capacity or divisibility indices; and these DAP's must also be monitored to avoid unthinking overloads or under-utilizations. DAP's may then transfer the signaling to a wired ‘trunk’ or background line; but the communication between DAP and SM's may assuredly be in a ‘noisy’ environment, for at least two readily foreseeable causes.

First, the physical environment of the SM's and DAP's may vary from sub-cell (one DAP, many SM's) to the next, and even within the same sub-cell as vehicles move about, doors open and close, and other physical events occur. So there may be also issues of interference for the network—both within one sub-cell (between SM's and their assigned DAP), and between sub-cells (from adjacent, i.e. geographically, immediately adjacent or overlapping) that are neighbors within the overall network.

Second, the communication between DAP and SM's, in one embodiment operates in the ISM band—which is a shared media. Other devices (e.g. smartphones, wireless printers, and computers) whose penetration and number are rapidly growing, and thus their message traffic, use the ISM band for their own purposes and with their own protocols, timing, and placements that may be ever-changing and unpredictable.

To effect wireless communication under such conditions reliably and efficiently needs digital signal processing which can handle complex, noisy, ‘dirty’ and above all uncontrolled and unpredictably varying communication conditions. This is the background in which the present description takes form.

The principle areas in which M2M communications may take place include (but are not limited to: utility networks (electricity, water, natural gas); industrial operations (as an obvious extension from the former, refineries; but also including manufacturing, distribution/logistical processing, warehousing, and transshipment operations particularly those switching between modes of transport, e.g. rail-and-truck or truck-and-ship); agricultural and pastoral production (large-scale planting, care, harvesting of grain, truck, or tree crops; or open- or closed-range herds); transportation networks (riverine, including barge/lock/bridge interactions; seaborne in channels, harbors, straits, or other ‘narrows’; airborne (around or between terminals); and road (including ‘convoy’ or ‘aggregate’ vehicle groupings or clusters); healthcare (intra- and inter-provider operations, remote servicing and communications); education (also intra- and inter-provider operations, remote servicing, Massively On-Line Open Courses, reverse-pyramid tutorial schemes, ‘educational portal’ services); all aspects of value exchange and financial transactions (credit, debit, swap; goods, services, or financial and other ‘intangibles’); and social media (ad-hoc peer narrow-, group-, peer-, or open-ended ‘casting’; messaging; social calendaring & coordination of ‘agents’). The similarity amongst these areas include the following key aspects:(a) Potentially high asymmetry between numbers of SM's at the lowest tier or “edge” of the network, and DAP's at higher tiers in the network.(b) Potentially high asymmetry in uplink and downlink transmission requirements between network tiers. In the most extreme case (and, in one embodiment, an advantageous case for this invention), SM's at the network edge may preferentially communicate data units to DAP's without any need to requirement for feedback from those DAP's, except for transport of infrequent physical-layer (PHY) messages to set or reset security protocols between the SM's and DAP's. Example services that meet this criterion include User Data Protocol (UDP) and Trivial File Transfer Protocol (TFTF) services.(c) Potentially high asymmetry in cost, complexity, size-weight-and-power (SWaP), and energy usage requirements between (typically “dumb”) SM's at the network edge and DAP's at higher tiers in the network.(b) Transmission of small data bursts, rather than extensive data-heavy, continuing linkages, with low average rate relative to human-centric operational ‘norm’ at the respective time.(d) Rapidly varying and highly dynamic variation in interference observed by SM's and DAP's, comprising both interference generated by the M2M network, and interference generated from emitters operating ‘outside’ the M2M network.

An individual human may have multiple ‘terminals’ in such an M2M network everything from physiological sensors in his clothing and accessories, to multiple communications and information-processing devices. An individual ‘origination point’ may be a single person, a single machine, a single household, or a single building with greater or lesser ‘interior’ differentiation and demands.

Power efficiency may be an important criterion for at least some members of the network, as wireless operations may require self-sufficiency for extended periods at non-predictable intervals; without fixed wires, power is more likely to be provisioned by batteries with weight and capacity limitations and thus be more expensive.

Additional important criteria for M2M networks and elements include: mobility, ubiquity, and minimization of maintenance costs (of servicing, of replacement elements, and of ‘opportunity of use’, i.e. downtime), especially at the network edge; and avoidance of network-centric SM authentication, association, and provisioning requirements that can unduly load the network downlink and create critical points of failure in the network. In particular, the ability to operate with limited or “local” provisioning of security keys can greatly improve robustness and scalability of the network, and (if successfully implemented) eliminate critical points of attack by adversaries seeking to corrupt or penetrate the M2M network.

All of the above criteria (and others known to the field but not specifically described here) generally militate towards a least-cost economic pressure; the networks that are pragmatically operable may be those that can most readily adapt to such. Unlike critical-path, ‘must succeed’ operations, M2M communications may have to accommodate localized failures, environmentally-caused intermittency, and be able to fail and then recover. The elements and networks can tolerate lower data transmission rates, transmission delays, and flawed communication handovers using the principle benefit of machines, persistence and exact repetition to overcome transient faults. They need not be as perfect as possible (in comparison to, say, a human-implanted medical support device), as durable as manufacturable (in comparison to, say, a multi-decade geosynchronous-orbit communications satellite), or even as secure against failure as imaginable (in comparison, say, to a nuclear reactor's in-pile operational machinery). Yet M2M networks and thus the individual elements therein must still be resistant (‘hardened’) against both inadvertent and intentional ‘spoofing’ effects (whether these arise from unintentional or intentional mistakes, environmentally-sourced distortions, and sabotage). Continued public acceptance of this approach to M2M networks and their intercommunications requires sustainably high confidence in the validity, verity, and non-distortability of such network's operations, for all SM's and DAP's, all of the time. The security of the network must be trusted even when real-world dangers, be those mistakes or temporary failures, or intentional efforts to misguide, intercept, spoof, or substitute network signals, are present. This security must be secured in and by the real world, rather than exist solely in some perfect model or algorithmic abstraction.

At the present time there are no fixed standards for M2M wireless communications networks that are universal, global, or national. There are cellular, Wi-Fi, and other ‘bands’ in the electromagnetic spectrum which might be used (and multiple combinations therein might be, also); and the distance ranges for such can shift from short, to close, to mid, to long range crossing the boundaries of skin, clothing, walls, and geography respectively.

Furthermore, because this is an evolving domain, changes can be anticipated to stay both rapid and continuing. Thus an open-ended, rather than closed, proprietary, solution may have the greatest utility. Changes may come to and from each and all of the use of the network, its provisioning and servicing capital (hardware and institutions), its spectra of transmission and reception (‘transception’); and its mode of interstitial operation (amplitude, frequency, temporal, spatial, and other diversities of transmission and reception). Chief concerns may include avoiding interference, using low-output power (if only to avoid deafening itself with ‘white noise’ from such), and intelligent application, sensitive to both the environmental conditions and human-imposed restrictions and requirements (whether regulatory, operational, or standards-compliant).

SUMMARY OF THE INVENTION

The present invention is a method for wireless intercommunication between a set of Signaling Machines (SM's) and a set of Data Aggregation Points (DAP's), comprising within a selected frequency range (in one embodiment, the 902-928 MHz ISM band) a frequency-hop direct-sequence (FHDS) spread-spectrum modulation format, which provides cyclic chip-level and symbol-level cyclic prefixes to control channel multipath and interference loading, and which preferentially employs transmission information that is randomly determined at every node in the network, and neither known to the receivers in the network nor provisioned by the network. On the uplink, this randomly determined transmission information includes:the physical dwell (time slot and frequency channel) used by each uplink transmit node in the network, which physical dwell is randomly varied over every time frame;the spreading code used by each uplink transmit node in the network, which spreading code is also randomly varied over every time frame; andelements of a source symbol mask applied to the data bursts prior to spreading, which source symbol mask is also randomly varied over every time frame.

Additionally, if multiple uplink receivers are in the field-of-view (FoV) of the uplink transmitter and have pathloss communication with those receivers, the uplink receiver selected by the uplink transmit node can also be randomly varied over each time frame. On the downlink, this randomly determined transmission information includes:the spreading code used by each downlink transmit node in the network, which spreading code is randomly varied in every time slot of each time frame; andelements of a source symbol mask applied to the data bursts prior to spreading, which source spreading mask is also randomly varied over every time frame.

Additionally, each downlink transmit node in the network transmits over a downlink frequency channel that is preferentially pseudorandomly varied over each time slot of each frame, using an algorithm that is provided to, known to, or learnable by each downlink receiver(s) allowed to communicate with that downlink transmit node, and which algorithm is locally and independently set at each downlink transmitter.

This randomly-determined transmission information can be provisioned at and by each transmitter, with each intended receiver being blind (no pre-set agreement or provisioning between transmitter and receiver) to the choice of that transmission information, and using only rudimentary provisioning from any specific transmitter in the network to only its set of intended receivers in the network of a commonly-known and shared receive symbol mask for all signals intended for a given receiver(s) so as to differentiate them from transmissions by that specific transmitter intended for other nodes in the network, as well as transmissions from other transmitters in the network intended for that particular receiver(s). The random spreading codes are further exploited at each receiver to differentiate between subsets of nodes transmitting to the same or different receivers in the network, preferentially using linear digital signal processing methods that can separate signals with widely varying receive power, and experiencing arbitrary channel multipath with group delay less than or equal to the cyclic prefix imposed during the spreading operation. This further permits the use of multiple time and frequency coincident transmissions and also avoids provisioning overhead (which reduces data transmission rates) required by using matched-filter despreading.

All of these enable higher security, by greatly complicating the task for any observer to determine actual in-use transmissions from noise; by eliminating the ability for an observer to predict the randomly determined transmission information used at the nodes in the network; and by using linear digital signal processing methods to excise intruders from legitimate network transmissions. For example, even if an intruder has learned the uplink receive symbol mask, so that the intruder can pose as a legitimate uplink transmission, the intruder may not be able to predict the randomly determined uplink transmission information used by any uplink transmitter in the network; will not be able to consistently jam any uplink transmitter in the network; may be instantly identified as a duplicated authorized node, or an unauthorized node, by the uplink receiver, allowing the uplink receive symbol mask to be reset by the system; and may in any event be excised by the linear digital signal processing methods employed by the uplink receiver.

One embodiment has the network exploit these arbitrary spreading codes, enabling this method to be used in any ad-hoc (not previously designated) set of SM's and DAP's, requiring only the preliminary commonalization (i.e. provisioning, of the symbol mask to the set of SM's and DAP's forming the ad-hoc network); and this method can be employed in any FDMA, TDMA, FHMA or OFDMA (Frequency Diverse Multiple Access; Time Diverse Multiple Access, Frequency Hop Multiple Access, Orthogonal Frequency Diverse Multiple Access) network without scheduling of intercommunications, thereby reducing the feedback response overhead cost. Because the despreading algorithms are not required to be pre-arranged, hard-coded, or otherwise communicated throughout the network, but can be least-common-knowledge shared, fully-blind in nature, they present the lowest overhead for any such approach, do not require carrier synchronization, and enable the SM's and DAP's (the network) to operate without either knowledge of a carrier offset or ‘handshake’ overhead signaling.

