Method and procedure for generating reputation scores for IoT devices based on distributed analysis

Aspects of the subject disclosure may include, for example, a method including obtaining a first set of votes from devices that are registered and enabled by a registration system to form a first network communicating with a processing system. The first set of votes relate to performance of a target device and indicate conformance to performance criteria for the first network. The processing system receives a reputation score for the target device from the registration system, and receives a second set of votes regarding target device performance from voting systems over a second network comprising a peer network including the processing system and the voting systems. The first and second sets of votes and the reputation score are aggregated to generate an updated reputation score for the target device. The registration system disables the target device when the reputation score falls below a threshold. Other embodiments are disclosed.

FIELD OF THE DISCLOSURE

The subject disclosure relates to machine-to-machine communication devices in the Internet of Things (IoT), and more particularly to a method and procedure for generating reputation scores for those devices.

BACKGROUND

The Internet of Things (IoT) is based on cloud computing and generally comprises networks of low-cost data-enabled sensors. A network-enabled residence can include multiple IoT devices and a gateway that facilitates an exchange of network traffic between remote entities and one or more devices at, near or otherwise associated with the residence.

DETAILED DESCRIPTION

The subject disclosure describes, among other things, illustrative embodiments of a system and method for validating registration of IoT devices by generating reputation scores for those devices. Other embodiments are described in the subject disclosure.

One or more aspects of the subject disclosure include a method comprising obtaining, by a processing system including a processor, a first set of votes from a plurality of devices; the devices are registered at and enabled by a registration system to form a first network communicating with the processing system. The first set of votes are with regard to performance of a target device and indicate a degree of conformance of the target device to performance criteria for the first network. The method also comprises receiving a reputation score for the target device from the registration system, and receiving a second set of votes regarding performance of the target device from a plurality of voting systems over a second network; the second network comprises a peer network including the processing system and the plurality of voting systems. The method further comprises aggregating the first set of votes, the reputation score, and the second set of votes to generate an updated reputation score for the target device. The method also comprises transmitting the updated reputation score for the target device to the registration system; the registration system disables the target device responsive to the updated reputation score being below a predetermined threshold.

One or more aspects of the subject disclosure include a device comprising a processing system including a processor, and a memory that stores executable instructions that, when executed by the processing system, facilitate performance of operations. The operations comprise obtaining a first set of votes from a plurality of devices; the plurality of devices are registered at and enabled by a registration system to form a first network communicating with the processing system. The first set of votes are with regard to performance of a target device and indicate a degree of conformance of the target device to performance criteria for the first network. The operations also comprise receiving a reputation score for the target device from the registration system, and receiving a second set of votes regarding performance of the target device from a plurality of voting systems over a second network; the second network comprises a peer network including the processing system and the plurality of voting systems, and the processing system is uniquely associated with the target device. The operations further comprise aggregating the first set of votes, the reputation score, and the second set of votes to generate an updated reputation score for the target device, and transmitting the updated reputation score for the target device to the registration system. The registration system disables the target device responsive to the updated reputation score being below a predetermined threshold; subsequent to disabling the target device, the registration system re-enables the target device according to a reputation score aging procedure.

One or more aspects of the subject disclosure include a machine-readable storage medium comprising executable instructions that, when executed by a processing system including a processor, facilitate performance of operations. The operations comprise obtaining a first set of votes from a plurality of devices registered at and enabled by a registration system to form a first network communicating with the processing system. The first set of votes are with regard to performance of a target device and indicate a degree of conformance of the target device to performance criteria for the first network, and the first set of votes is obtained via a multicast message. The operations also comprise receiving a reputation score for the target device from the registration system, and receiving a second set of votes regarding performance of the target device from a plurality of voting systems over a second network. The second network comprises a peer network including the processing system and the plurality of voting systems, and the processing system is uniquely associated with the target device. The operations further comprise aggregating the first set of votes, the reputation score, and the second set of votes to generate an updated reputation score for the target device, and transmitting the updated reputation score for the target device to the registration system. The registration system disables the target device responsive to the updated reputation score being below a predetermined threshold.

In accordance with the embodiments described below, the subject disclosure provides a protocol to ensure that registration and enabling of a new IoT device also involves device monitoring and validation. In these embodiments, an IoT device is allowed to connect to a network, but has a neutral reputation until its behavior on the network is determined to conform to a predetermined standard, profile or baseline. The protocol is implemented using a distributed voting scheme. This is accomplished through interactions with other IoT devices on the same network and with network routing and switching elements. A new device's behavior over time establishes its reputation, which is expressed as a reputation score; the reputation score is thus an indicator of trustworthiness of the device.

Referring now toFIG. 1, a block diagram is shown illustrating an example, non-limiting embodiment of a communications network100in accordance with various aspects described herein. Network100can include processing systems for registering, enabling and monitoring IoT devices, and generating reputation scores for those devices, as detailed below.

FIG. 2Ais a block diagram illustrating an example, non-limiting embodiment201of a system functioning within the communication network ofFIG. 1and in accordance with various aspects described herein. As shown inFIG. 2A, a residence212has installed therein a group210of network-accessible devices (IoT devices). An IoT device211can be any one or more of a home security system (for example, including one or more of cameras, motion sensors, entry detectors, smoke and/or CO2detectors); smart home sensors and/or controllers (for example, smart thermostats, lighting controls, door entry controls); and user devices (for example, computers, tablet devices, VoIP telephones, mobile phones, remote controllers, game consoles, media processors, smart televisions, or personal digital assistants). It is understood that IoT devices, as referred to herein, can include virtually any network accessible device, such as a home appliance, a utility appliance, such as a utility meter, a vehicle, and/or any other device that participates in M2M communications.

In this embodiment, the group210of devices can be understood as a local area network (LAN) which can communicate with other networks via a registration gateway213. Furthermore, the device network210communicates with a network215of voting managers; the voting managers collect and analyze votes regarding performance of the IoT devices and generate reputation scores for the devices, as detailed below. The registration gateway213and voting manager network215retrieve device reputation information from, and send updated reputation information to, reputation database217.

In general, the performance of a given device on network210can be evaluated by comparing event data regarding the device (for example, traffic volume to or from another network device) with predetermined performance criteria. In various embodiments, a performance criterion regarding traffic volume can be expressed as a traffic threshold. A device associated with traffic exceeding the threshold can thus be voted on negatively by other devices. Other non-limiting examples of performance criteria include a set of IP addresses that can properly be accessed by a device and a set of actions that can properly be performed or requested by a device. If a device contacts an improper address or otherwise performs improperly (“bad behavior”), negative votes regarding the device will be directed by the other network devices to the voting manager network215. The reputation score for the device will accordingly be reduced. In various embodiments, a device with a reputation score falling below a threshold can be removed from the network (“rogue” or “malicious” device).

In this embodiment, registration gateway213serves as device manager for the devices of network210, and is responsible for authenticating the IoT devices. Registration gateway213can also receive data from an external reputation data feed216(that is, a source of reputation data other than votes gathered by the voting manager network215).

FIG. 2Bschematically illustrates an example, non-limiting embodiment202of a system functioning within the communication network ofFIG. 1in which public and private IoT devices communicate with a network of voting managers.

The voting manager network215is hosted in the cloud and includes voting manager components225. The voting manager network aggregates votes from the devices of network210regarding performance of those devices; in general, for a network210having N devices, the voting manager network215continually receives votes regarding each device from the other N−1 devices. (A particular device whose performance is being monitored and voted on will be referred to herein as the target device.) As shown inFIG. 2B, voting is not centralized because all devices sending data to a single point of failure could degrade performance. In this embodiment, a decentralized voting algorithm is used in which the voting manager components225arrive at a consensus similar to a voting result that would be obtained with a centralized voting manager. For each target device under review, one voting manager component is designated as the root component; the root component leads the vote pertaining to that target device, as explained in detail below.

In various embodiments, IoT devices can include private and public devices based on their scope of use. A device attached to a single household (for example, a device belonging to local network210) would be a private device, while a device attached to a public or common area such as a traffic sensor or a surveillance camera would be a public device (for example, device222attached to street sign221). The registration gateway213can be adapted to have a hierarchical structure for registering public and private devices at different levels of trust. In general, public devices have a higher level of trust than private devices; public and private devices therefore can be assigned different weights by the voting algorithm.

In this embodiment, each IoT device (either a public device or a private device on a local residential network) maintains certain basic information:(a) A list of valid IP addresses: These are endpoints that the IoT device should interact with for normal functionality(b) A list of allowed services(c) A set of thresholds for traffic for each allowed service(d) A multicast address for the voting managers(e) The address of the registration gateway
Each IoT device collects data regarding network traffic that it experiences. When a threshold is crossed, the IoT device transmits a User Datagram Protocol (UDP) packet via multicast to the voting manager network215; the packet corresponds to a vote indicating that aberrant network behavior is occurring.

FIG. 2Cschematically illustrates an example, non-limiting embodiment203of a system functioning within the communication network ofFIG. 1, in which a network of voting managers215collects and analyzes votes from IoT devices operating on multiple local networks210. For each device on the network, registration gateway213provides an initial or baseline reputation score to the voting manager network when the device is enabled.

An external reputation information source, shown inFIG. 2Cas a server231, can transmit a reputation score to the registration gateway. In an embodiment, the external information source can transmit information to the voting manager network regarding threats to the network.

Each target IoT device (for example, device211) is associated with one voting manager component (for example, component235), referred to herein as the root voting manager component for that device. In this embodiment, each IoT device has a universal unique identifier (UUID) and each voting manager component has a distinct identifier; these two identifiers are concatenated to form a unique tag, which is then hashed using a hashing algorithm (for example, Message Digest algorithm MD6). A hash tag value is thus generated for each voting manager component. The voting manager component having the lowest hash tag value is designated the root for the target device.

In this embodiment, each IoT device converts its network traffic information into a timeline of positive and negative event scores (votes) that are sent to the voting manager network via multicast. It will be appreciated that multiple voting manager components may thus receive votes from a particular device; this reduces the risk of a vote being lost. All votes from a given device are forwarded to the root voting manager associated with the device. In this embodiment, each vote contains a unique identifier to prevent it being counted multiple times.

In an IoT device network having a large number of sites (endpoints) monitoring traffic and submitting votes regarding a suspect event, a single event may trigger a correspondingly large number of votes. In an embodiment, reputation scores are scaled according to the number of voting devices so that a single event is interpreted appropriately (for example, so that the event is not judged by the voting managers as more severe than it actually is).

Each IoT device can monitor traffic at a variety of IP addresses, and generate a negative vote if traffic from a particular IP address exceeds a threshold. In this embodiment, each IoT device can also track connections or traffic at invalid locations or involving invalid services; flag traffic from invalid locations; or flag requests from addresses not recognized by the network. Any of these events can result in a multicast message to the voting manager network. In an embodiment, the message can include details of the suspect event (for example, the amount of traffic that exceeded the threshold level, or an identifier of an improperly accessed IP address).

A vote can be binary (that is, represented by a binary digit 1 or 0) indicating whether or not a device is meeting minimum performance criteria. Alternatively, a vote can have a numeric value over a range (for example, 1 to 10 or −100 to +100).

Each voting manager component collects event data received directly from the IoT devices or via a voting proxy. In an embodiment, the voting devices communicate with the registration gateway, which serves as a voting proxy. The voting manager components also receive reputation scores from the registration gateway for the devices being monitored.

The votes from the IoT devices, pertaining to a given target device, are routed to the root voting manager component associated with that device. In this embodiment, the votes from the IoT devices are weighted, with votes from devices having good reputations counting for more than votes from devices having poor reputations.

According to the voting algorithm in this embodiment, the voting manager components communicate with each other to determine the reputation score for a target device. Each voting manager component sends the root voting manager its estimate of the reputation score for the target device. The root voting manager aggregates the inputs from the other voting manager components with the existing reputation score for the device, and sends a new reputation score to the registration gateway.

In this embodiment, the registration gateway queries the external reputation information source (reputation data feed) for any additional information regarding the target device. The registration gateway then revises the new reputation score if necessary, and stores the reputation score in database217.

The registration gateway can apply a reputation score threshold, and information from the reputation data feed, to determine whether the target device should be removed from the network. For example, if the score is slightly negative (but not below the threshold) and the target device has a flag in the reputation feed, or if the score is strongly negative (below the threshold), the registration gateway can drop the device from the network. In an embodiment, the registration gateway maintains a roster of enabled devices, and removes the suspect device from the roster.

In an embodiment, the above-described voting process repeats continually, with a new reputation score being determined on a timed basis. For example, when a new device joins the network its reputation score can be determined frequently, but over time as its score remains stable and positive, the reputation score can be determined less frequently until event data triggers a threshold and/or a timer is reset to reconsider the device as new and possibly suspect.

FIG. 2Dis a flowchart depicting an illustrative embodiment of a method204performed by the registration gateway, in accordance with various aspects described herein. In step2411, the registration gateway registers a new IoT device with a network (for example, a local network210having devices within, proximate to, or otherwise associated with a residence212). If an external reputation data feed can provide data regarding a reputation score for the new device (step2412), the initial reputation score is computed based on that information (step2413); if not, the reputation score is set to a default value, e.g. zero (step2414).

The registration gateway then enables the IoT device (step2415), so that the device has access to other devices on the network and to the voting manager network. At this point, the IoT device is enabled with its initial (or default) reputation score. In this embodiment, the reputation score for a recently enabled device will be computed and updated more frequently than those of other devices.

In step2416, the registration gateway provides the current reputation score for the device to the voting manager network. The voting manager network then proceeds to collect votes (step2417); in an embodiment, the registration gateway plays the role of proxy by delivering the votes to the voting manager network. Alternatively, another device on the network such as a router can forward votes to the voting manager network.

The registration gateway receives the updated reputation score (step2418); in this embodiment, the reputation score is received from the root voting manager component associated with the target device. The registration gateway then applies any additional data regarding device reputation obtained from the external reputation feed (step2419) to determine the new reputation score.

If (step2420) the score does not meet minimum network criteria (for example, the score is below a predetermined threshold or the external reputation feed has flagged some event involving the target device), the registration gateway proceeds to disable the target device (step2421). Otherwise, the registration gateway provides the new score to the voting manager network and the voting process continues.

FIG. 2Eis a flowchart depicting an illustrative embodiment of a method205performed by IoT devices in the local network, in accordance with various aspects described herein. After being registered and enabled by the registration gateway (step2511), each device monitors traffic and connections at other devices (step2512). In this embodiment, a device collects event data (step2513) relating to traffic volume at other devices, connections to invalid ports or for invalid services, and/or traffic from invalid locations. Each device then converts the event data into a vote pertaining to another device (step2514). In this embodiment, the vote is a numeric value that can be positive or negative. The IoT devices then send their votes to the voting manager network via multicast (step2515).

FIG. 2Fis a flowchart depicting an illustrative embodiment of a method206performed by voting managers, in accordance with various aspects described herein. In step2611, a root voting manager is determined for an IoT device; as explained above, this can be done by combining identifier numbers for the target device and for each voting manager component, using a hash algorithm to generate a hash value for each voting manager component with respect to the target device, and selecting the voting manager component with the lowest hash value.

The voting manager network then receives a current reputation score for the target device from the registration gateway (step2612), and receives votes from the various IoT devices via multicast (step2613). Votes can be weighted according to the reputation score of the voting device, and/or whether the device is public or private.

The root voting manager interacts with other voting manager components to decide on a reputation score for the target device. Each of the other voting manager components sends the root its vote regarding a new reputation score for the target device (step2614). Since the voting process is ongoing, these votes are continually updated. If the timer determines that a new score should be computed for the target device (step2615), the root combines the votes and the existing reputation score (step2616), and sends a combined/aggregated score to the registration gateway (step2617).

FIG. 2Gis a flowchart depicting an illustrative embodiment of a method207performed by the registration gateway to re-enable a device, in accordance with various aspects described herein. In step2711, the registration gateway determines an elapsed time since a device was disabled. The registration gateway then applies an aging factor to the reputation score (step2712). In an embodiment, the device reputation score may be assigned a half-life time period, so that at after one such time period a score of −100 becomes −50, after a second time period the score becomes −25, and so on until a threshold is reached (for example, −5) for restoration to the network. If the reputation score has been restored to meet this threshold (step2713), the registration gateway proceeds to re-enable the device. Alternatively, the registration gateway can re-enable a device on receiving a message (an event flag) that a remedial action (a patch) has been applied to the device to mitigate its previous bad behavior. In another embodiment, manual input by a system user is required to re-enable the device after the reputation score has been restored.

FIG. 2His a sequence diagram208depicting an illustrative embodiment of procedures performed in accordance with various aspects described herein. In the embodiment shown inFIG. 2H, an IoT registration and reputation scoring system performs procedures2801-2804:

Initial registration procedure2801includes enablement of IoT devices and granting of conditional access by the registration gateway. The registration gateway also sends a baseline reputation score to the voting manager (which can be a distributed network as described above). A third-party reputation information source2815sends the voting manager and registration gateway information feeds2816,2817including known threats to the network.

Voting procedure2802includes detection of improper activity2821by an IoT device2810. Another IoT device sends a report2822to the registration gateway. In this embodiment, the registration gateway collects votes2825from other devices; all these reports and votes are sent to the voting manager via multicast2827. The voting manager can also receive votes2828from sources outside the network.

Device exclusion procedure2803includes revocation by the registration gateway of network access for device2810, in response to a decision2831by the voting manager that device2810has performed improperly. In this embodiment, the voting manager can also send a message2832to the third-party information source2815that includes attributes of device2810.

Device restoration procedure2804includes a notification2841from the excluded device to the registration gateway that the device has been patched, and should therefore be re-admitted to the network. In response to this notification, the registration gateway again grants device2810conditional access to the network.

FIG. 2Iis a sequence diagram209depicting an illustrative embodiment of procedures performed in accordance with various aspects described herein. In the embodiment shown inFIG. 2I, the voting manager components interact with each other and with IoT devices by performing procedures2901-2903:

In IoT site registration procedure2901, IoT devices at endpoints (sites)2911,2912of a network are respectively associated with voting managers2913,2914of the voting manager network. As explained above, one voting manager of the voting manager network can be designated as the root voting manager for a device.

In voting manager consensus procedure2902, all of the voting manager components of the network exchange messages according to a root protocol, to arrive at a consensus reputation score for each of the IoT devices.

In root identification procedure2903, the designated root voting managers2913,2914send their identifiers to their respective IoT devices2911,2912, and receive messages from those devices acknowledging that the devices are assigned to those root voting managers.

While for purposes of simplicity of explanation, the respective processes are shown and described as a series of blocks inFIGS. 2D-2Gand are shown in a particular order inFIGS. 2H-2I, it is to be understood and appreciated that the claimed subject matter is not so limited, as some processes may occur in different orders and/or concurrently with other processes from what is depicted and described herein. Moreover, not all illustrated blocks or processes may be required to implement the methods described herein.

Referring now toFIG. 3, a block diagram is shown illustrating an example, non-limiting embodiment of a virtualized communication network300in accordance with various aspects described herein. Network300includes virtual elements that can perform the above-described operations of obtaining content, generating and storing versions of content, configuring presentation of content versions, and providing alternate presentation versions based on audience reactions. In particular, virtualized communication network300can be used to implement some or all of the subsystems and functions of communication network100, the subsystems and functions of systems201-204, and method205presented inFIGS. 1, 2A, 2B, 2C, 2D and 2E.

Turning now toFIG. 4, there is illustrated a block diagram of a computing environment400in which various aspects of the subject disclosure can be implemented. In particular, computing environment400can be used in the implementation of network elements150,152,154,156, access terminal112, base station or access point122, switching device132, media terminal142, and/or VNEs330,332,334, etc. Each of these devices can be implemented via computer-executable instructions that can run on one or more computers, and/or in combination with other program modules and/or as a combination of hardware and software.

When used in a LAN networking environment, the computer402can be connected to the local network452through a wired and/or wireless communication network interface or adapter456. The adapter456can facilitate wired or wireless communication to the LAN452, which can also comprise a wireless AP disposed thereon for communicating with the wireless adapter456.

It is to be noted that server(s)514can comprise one or more processors configured to confer at least in part the functionality of macro wireless network platform510. To that end, the one or more processor can execute code instructions stored in memory530, for example. It is should be appreciated that server(s)514can comprise a content manager, which operates in substantially the same manner as described hereinbefore.

Turning now toFIG. 6, an illustrative embodiment of a communication device600is shown. The communication device600can serve as an illustrative embodiment of devices such as data terminals114, mobile devices124, vehicle126, display devices144or other client devices for communication via either communications network125.

In various embodiments, network communications can be facilitated using a guided wave communications system, as described below.

In an embodiment, a guided wave communication system is presented for sending and receiving communication signals such as data or other signaling via guided electromagnetic waves. The guided electromagnetic waves include, for example, surface waves or other electromagnetic waves that are bound to or guided by a transmission medium as described herein. It will be appreciated that a variety of transmission media can be utilized with guided wave communications without departing from example embodiments. Examples of such transmission media can include one or more of the following, either alone or in one or more combinations: wires, whether insulated or not, and whether single-stranded or multi-stranded; conductors of other shapes or configurations including unshielded twisted pair cables including single twisted pairs, Category 5e and other twisted pair cable bundles, other wire bundles, cables, rods, rails, pipes; non-conductors such as dielectric pipes, rods, rails, or other dielectric members; combinations of conductors and dielectric materials such as coaxial cables; or other guided wave transmission media.

The inducement of guided electromagnetic waves that propagate along a transmission medium can be independent of any electrical potential, charge or current that is injected or otherwise transmitted through the transmission medium as part of an electrical circuit. For example, in the case where the transmission medium is a wire, it is to be appreciated that while a small current in the wire may be formed in response to the propagation of the electromagnetic waves guided along the wire, this can be due to the propagation of the electromagnetic wave along the wire surface, and is not formed in response to electrical potential, charge or current that is injected into the wire as part of an electrical circuit. The electromagnetic waves traveling along the wire therefore do not require an electrical circuit (i.e., ground or other electrical return path) to propagate along the wire surface. The wire therefore is a single wire transmission line that is not part of an electrical circuit. For example, electromagnetic waves can propagate along a wire configured as an electrical open circuit. Also, in some embodiments, a wire is not necessary, and the electromagnetic waves can propagate along a single line transmission medium that is not a wire including a single line transmission medium that is conductorless. Accordingly, electromagnetic waves can propagate along a physical transmission medium without requiring an electrical return path.

More generally, “guided electromagnetic waves” or “guided waves” as described by the subject disclosure are affected by the presence of a physical object that is at least a part of the transmission medium (e.g., a bare wire or other conductor, a dielectric including a dielectric core without a conductive shield and/or without an inner conductor, an insulated wire, a conduit or other hollow element whether conductive or not, a bundle of insulated wires that is coated, covered or surrounded by a dielectric or insulator or other wire bundle, or another form of solid, liquid or otherwise non-gaseous transmission medium) so as to be at least partially bound to or guided by the physical object and so as to propagate along a transmission path of the physical object. Such a physical object can operate as at least a part of a transmission medium that guides, by way of one or more interfaces of the transmission medium (e.g., an outer surface, inner surface, an interior portion between the outer and the inner surfaces or other boundary between elements of the transmission medium). In this fashion, a transmission medium may support multiple transmission paths over different surfaces of the transmission medium. For example, a stranded cable or wire bundle may support electromagnetic waves that are guided by the outer surface of the stranded cable or wire bundle, as well as electromagnetic waves that are guided by inner cable surfaces between two, three or more individual strands or wires within the stranded cable or wire bundle. For example, electromagnetic waves can be guided within interstitial areas of a stranded cable, insulated twisted pair wires, or a wire bundle. The guided electromagnetic waves of the subject disclosure are launched from a sending (transmitting) device and propagate along the transmission medium for reception by at least one receiving device. The propagation of guided electromagnetic waves, can carry energy, data and/or other signals along the transmission path from the sending device to the receiving device.

As used herein the term “conductor” (based on a definition of the term “conductor” fromIEEE100, the Authoritative Dictionary of IEEE Standards Terms,7thEdition, 2000) means a substance or body that allows a current of electricity to pass continuously along it. The terms “insulator”, “conductorless” or “nonconductor” (based on a definition of the term “insulator” fromIEEE100, the Authoritative Dictionary of IEEE Standards Terms,7thEdition, 2000) means a device or material in which electrons or ions cannot be moved easily. It is possible for an insulator, or a conductorless or nonconductive material to be intermixed intentionally (e.g., doped) or unintentionally into a resulting substance with a small amount of another material having the properties of a conductor. However, the resulting substance may remain substantially resistant to a flow of a continuous electrical current along the resulting substance. Furthermore, a conductorless member such as a dielectric rod or other conductorless core lacks an inner conductor and a conductive shield. As used herein, the term “eddy current” (based on a definition of the term “conductor” fromIEEE100, the Authoritative Dictionary of IEEE Standards Terms,7thEdition, 2000) means a current that circulates in a metallic material as a result of electromotive forces induced by a variation of magnetic flux. Although it may be possible for an insulator, conductorless or nonconductive material in the foregoing embodiments to allow eddy currents that circulate within the doped or intermixed conductor and/or a very small continuous flow of an electrical current along the extent of the insulator, conductorless or nonconductive material, any such continuous flow of electrical current along such an insulator, conductorless or nonconductive material is de minimis compared to the flow of an electrical current along a conductor. Accordingly, in the subject disclosure an insulator, and a conductorless or nonconductor material are not considered to be a conductor. The term “dielectric” means an insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not continuously flow through the material as they do in a conductor, but only slightly shift from their average equilibrium positions causing dielectric polarization. The terms “conductorless transmission medium or non-conductor transmission medium” can mean a transmission medium consisting of any material (or combination of materials) that may or may not contain one or more conductive elements but lacks a continuous conductor between the sending and receiving devices along the conductorless transmission medium or non-conductor transmission medium—similar or identical to the aforementioned properties of an insulator, conductorless or nonconductive material.

Unlike free space propagation of wireless signals such as unguided (or unbounded) electromagnetic waves that decrease in intensity inversely by the square of the distance traveled by the unguided electromagnetic waves, guided electromagnetic waves can propagate along a transmission medium with less loss in magnitude per unit distance than experienced by unguided electromagnetic waves.

Unlike electrical signals, guided electromagnetic waves can propagate along different types of transmission media from a sending device to a receiving device without requiring a separate electrical return path between the sending device and the receiving device. As a consequence, guided electromagnetic waves can propagate from a sending device to a receiving device along a conductorless transmission medium including a transmission medium having no conductive components (e.g., a dielectric strip, rod, or pipe), or via a transmission medium having no more than a single conductor (e.g., a single bare wire or insulated wire configured in an open electrical circuit). Even if a transmission medium includes one or more conductive components and the guided electromagnetic waves propagating along the transmission medium generate currents that flow in the one or more conductive components in a direction of the guided electromagnetic waves, such guided electromagnetic waves can propagate along the transmission medium from a sending device to a receiving device without requiring a flow of opposing currents on an electrical return path between the sending device and the receiving device (i.e., in an electrical open circuit configuration).

In a non-limiting illustration, consider electrical systems that transmit and receive electrical signals between sending and receiving devices by way of conductive media. Such systems generally rely on an electrical forward path and an electrical return path. For instance, consider a coaxial cable having a center conductor and a ground shield that are separated by an insulator. Typically, in an electrical system a first terminal of a sending (or receiving) device can be connected to the center conductor, and a second terminal of the sending (or receiving) device can be connected to the ground shield or other second conductor. If the sending device injects an electrical signal in the center conductor via the first terminal, the electrical signal will propagate along the center conductor causing forward currents in the center conductor, and return currents in the ground shield or other second conductor. The same conditions apply for a two terminal receiving device.

In contrast, consider a guided wave communication system such as described in the subject disclosure, which can utilize different embodiments of a transmission medium (including among others a coaxial cable) for transmitting and receiving guided electromagnetic waves without requiring an electrical return path. In one embodiment, for example, the guided wave communication system of the subject disclosure can be configured to induce guided electromagnetic waves that propagate along an outer surface of a coaxial cable. Although the guided electromagnetic waves can cause forward currents on the ground shield, the guided electromagnetic waves do not require return currents on, for example, the center conductor to enable the guided electromagnetic waves to propagate along the outer surface of the coaxial cable. The same can be said of other transmission media used by a guided wave communication system for the transmission and reception of guided electromagnetic waves. For example, guided electromagnetic waves induced by the guided wave communication system on a bare wire, an insulated wire, or a dielectric transmission medium (e.g., a dielectric core with no conductive materials), can propagate along the bare wire, the insulated bare wire, or the dielectric transmission medium without requiring return currents on an electrical return path.

Consequently, electrical systems that require forward and return conductors for carrying corresponding forward and reverse currents on conductors to enable the propagation of electrical signals injected by a sending device are distinct from guided wave systems that induce guided electromagnetic waves on an interface of a transmission medium without requiring an electrical return path to enable the propagation of the guided electromagnetic waves along the interface of the transmission medium. It is also noted that a transmission medium having an electrical return path (e.g., ground) for purposes of conducting currents (e.g., a power line) can be used to contemporaneously propagate electromagnetic waves along the transmission medium. However, the propagation of the electromagnetic waves is not dependent on the electrical currents flowing through the transmission medium. For example, if the electrical currents flowing through the transmission medium stop flowing for any reason (e.g., a power outage), electromagnetic waves propagating along the transmission medium can continue to propagate without interruption.

It is further noted that guided electromagnetic waves as described in the subject disclosure can have an electromagnetic field structure that lies primarily or substantially on an outer surface of a transmission medium so as to be bound to or guided by the outer surface of the transmission medium and so as to propagate non-trivial distances on or along the outer surface of the transmission medium. In other embodiments, guided electromagnetic waves can have an electromagnetic field structure that substantially lies above an outer surface of a transmission medium, but is nonetheless bound to or guided by the transmission medium and so as to propagate non-trivial distances on or along the transmission medium. In other embodiments, guided electromagnetic waves can have an electromagnetic field structure that has a field strength that is de minimis at the outer surface, below the outer surface, and/or in proximity to the outer surface of a transmission medium, but is nonetheless bound to or guided by the transmission medium and so as to propagate non-trivial distances along the transmission medium. In other embodiments, guided electromagnetic waves can have an electromagnetic field structure that lies primarily or substantially below an outer surface of a transmission medium so as to be bound to or guided by an inner material of the transmission medium (e.g., dielectric material) and so as to propagate non-trivial distances within the inner material of the transmission medium. In other embodiments, guided electromagnetic waves can have an electromagnetic field structure that lies within a region that is partially below and partially above an outer surface of a transmission medium so as to be bound to or guided by this region of the transmission medium and so as to propagate non-trivial distances along this region of the transmission medium. It will be appreciated that electromagnetic waves that propagate along a transmission medium or are otherwise guided by a transmission medium (i.e., guided electromagnetic waves) can have an electric field structure such as described in one or more of the foregoing embodiments. The desired electromagnetic field structure in an embodiment may vary based upon a variety of factors, including the desired transmission distance, the characteristics of the transmission medium itself, environmental conditions/characteristics outside of the transmission medium (e.g., presence of rain, fog, atmospheric conditions, etc.), and characteristics of an electromagnetic wave that are configurable by a launcher as will be described below (e.g., configurable wave mode, configurable electromagnetic field structure, configurable polarity, configurable wavelength, configurable bandwidth, and so on).

Various embodiments described herein relate to coupling devices, that can be referred to as “waveguide coupling devices”, “waveguide couplers” or more simply as “couplers”, “coupling devices” or “launchers” for launching and/or receiving/extracting guided electromagnetic waves to and from a transmission medium, wherein a wavelength of the guided electromagnetic waves can be small compared to one or more dimensions of the coupling device and/or the transmission medium such as the circumference of a wire or other cross sectional dimension. Such electromagnetic waves can operate at millimeter wave frequencies (e.g., 30 to 300 GHz), or lower than microwave frequencies such as 300 MHz to 30 GHz. Electromagnetic waves can be induced to propagate along a transmission medium by a coupling device, such as: a strip, arc or other length of dielectric material; a millimeter wave integrated circuit (MMIC), a horn, monopole, dipole, rod, slot, patch, planar or other antenna; an array of antennas; a magnetic resonant cavity or other resonant coupler; a coil, a strip line, a coaxial waveguide, a hollow waveguide, or other waveguide and/or other coupling device. In operation, the coupling device receives an electromagnetic wave from a transmitter or transmission medium. The electromagnetic field structure of the electromagnetic wave can be carried below an outer surface of the coupling device, substantially on the outer surface of the coupling device, within a hollow cavity of the coupling device, can be radiated from a coupling device or a combination thereof. When the coupling device is in close proximity to a transmission medium, at least a portion of an electromagnetic wave couples to or is bound to the transmission medium, and continues to propagate as guided electromagnetic waves along the transmission medium. In a reciprocal fashion, a coupling device can receive or extract at least a portion of the guided electromagnetic waves from a transmission medium and transfer these electromagnetic waves to a receiver. The guided electromagnetic waves launched and/or received by the coupling device propagate along the transmission medium from a sending device to a receiving device without requiring an electrical return path between the sending device and the receiving device. In this circumstance, the transmission medium acts as a waveguide to support the propagation of the guided electromagnetic waves from the sending device to the receiving device.

According to an example embodiment, a surface wave is a type of guided wave that is guided by a surface of a transmission medium, such as an exterior or outer surface or an interior or inner surface including an interstitial surface of the transmission medium such as the interstitial area between wires in a multi-stranded cable, insulated twisted pair wires, or wire bundle, and/or another surface of the transmission medium that is adjacent to or exposed to another type of medium having different properties (e.g., dielectric properties). Indeed, in an example embodiment, a surface of the transmission medium that guides a surface wave can represent a transitional surface between two different types of media. For example, in the case of a bare wire or uninsulated wire, the surface of the wire can be the outer or exterior conductive surface of the bare wire or uninsulated wire that is exposed to air or free space. As another example, in the case of insulated wire, the surface of the wire can be the conductive portion of the wire that meets an inner surface of the insulator portion of the wire. A surface of the transmission medium can be any one of an inner surface of an insulator surface of a wire or a conductive surface of the wire that is separated by a gap composed of, for example, air or free space. A surface of a transmission medium can otherwise be any material region of the transmission medium. For example, the surface of the transmission medium can be an inner portion of an insulator disposed on a conductive portion of the wire that meets the insulator portion of the wire. The surface that guides an electromagnetic wave can depend upon the relative differences in the properties (e.g., dielectric properties) of the insulator, air, and/or the conductor and further dependent on the frequency and propagation mode or modes of the guided wave.

According to an example embodiment, the term “about” a wire or other transmission medium used in conjunction with a guided wave can include fundamental guided wave propagation modes such as a guided wave having a circular or substantially circular field pattern/distribution, a symmetrical electromagnetic field pattern/distribution (e.g., electric field or magnetic field) or other fundamental mode pattern at least partially around a wire or other transmission medium. Unlike Zenneck waves that propagate along a single planar surface of a planar transmission medium, the guided electromagnetic waves of the subject disclosure that are bound to a transmission medium can have electromagnetic field patterns that surround or circumscribe, at least in part, a non-planar surface of the transmission medium with electromagnetic energy in all directions, or in all but a finite number of azimuthal null directions characterized by field strengths that approach zero field strength for infinitesimally small azimuthal widths.

For example, such non-circular field distributions can be unilateral or multi-lateral with one or more axial lobes characterized by relatively higher field strength and/or one or more nulls directions of zero field strength or substantially zero-field strength or null regions characterized by relatively low-field strength, zero-field strength and/or substantially zero-field strength. Further, the field distribution can otherwise vary as a function of azimuthal orientation around a transmission medium such that one or more angular regions around the transmission medium have an electric or magnetic field strength (or combination thereof) that is higher than one or more other angular regions of azimuthal orientation, according to an example embodiment. It will be appreciated that the relative orientations or positions of the guided wave higher order modes, particularly asymmetrical modes, can vary as the guided wave travels along the wire.

In addition, when a guided wave propagates “about” a wire or other type of transmission medium, it can do so according to a guided wave propagation mode that includes not only the fundamental wave propagation modes (e.g., zero order modes), but additionally or alternatively, non-fundamental wave propagation modes such as higher-order guided wave modes (e.g., 1storder modes, 2ndorder modes, etc.). Higher-order modes include symmetrical modes that have a circular or substantially circular electric or magnetic field distribution and/or a symmetrical electric or magnetic field distribution, or asymmetrical modes and/or other guided (e.g., surface) waves that have non-circular and/or asymmetrical field distributions around the wire or other transmission medium. For example, the guided electromagnetic waves of the subject disclosure can propagate along a transmission medium from the sending device to the receiving device or along a coupling device via one or more guided wave modes such as a fundamental transverse magnetic (TM) TM00 mode (or Goubau mode), a fundamental hybrid mode (EH or HE) “EH00” mode or “HE00” mode, a transverse electromagnetic “TEMnm” mode, a total internal reflection (TIR) mode or any other mode such as EHnm, HEnm or TMnm, where n and/or m have integer values greater than or equal to 0, and other fundamental, hybrid and non-fundamental wave modes.

As used herein, the term “guided wave mode” refers to a guided wave propagation mode of a transmission medium, coupling device or other system component of a guided wave communication system that propagates for non-trivial distances along the length of the transmission medium, coupling device or other system component.

As used herein, the term “millimeter-wave” can refer to electromagnetic waves/signals that fall within the “millimeter-wave frequency band” of 30 GHz to 300 GHz. The term “microwave” can refer to electromagnetic waves/signals that fall within a “microwave frequency band” of 300 MHz to 300 GHz. The term “radio frequency” or “RF” can refer to electromagnetic waves/signals that fall within the “radio frequency band” of 10 kHz to 1 THz. It is appreciated that wireless signals, electrical signals, and guided electromagnetic waves as described in the subject disclosure can be configured to operate at any desirable frequency range, such as, for example, at frequencies within, above or below millimeter-wave and/or microwave frequency bands. In particular, when a coupling device or transmission medium includes a conductive element, the frequency of the guided electromagnetic waves that are carried by the coupling device and/or propagate along the transmission medium can be below the mean collision frequency of the electrons in the conductive element. Further, the frequency of the guided electromagnetic waves that are carried by the coupling device and/or propagate along the transmission medium can be a non-optical frequency, e.g., a radio frequency below the range of optical frequencies that begins at 1 THz.

It is further appreciated that a transmission medium as described in the subject disclosure can be configured to be opaque or otherwise resistant to (or at least substantially reduce) a propagation of electromagnetic waves operating at optical frequencies (e.g., greater than 1 THz).

As used herein, the term “antenna” can refer to a device that is part of a transmitting or receiving system to transmit/radiate or receive free space wireless signals.

Referring now toFIG. 7, a block diagram700illustrating an example, non-limiting embodiment of a guided wave communications system is shown. In operation, a transmission device701receives one or more communication signals710from a communication network or other communications device that includes data and generates guided waves720to convey the data via the transmission medium725to the transmission device702. The transmission device702receives the guided waves720and converts them to communication signals712that include the data for transmission to a communications network or other communications device. The guided waves720can be modulated to convey data via a modulation technique such as phase shift keying, frequency shift keying, quadrature amplitude modulation, amplitude modulation, multi-carrier modulation such as orthogonal frequency division multiplexing and via multiple access techniques such as frequency division multiplexing, time division multiplexing, code division multiplexing, multiplexing via differing wave propagation modes and via other modulation and access strategies.

The communication network or networks can include a wireless communication network such as a mobile data network, a cellular voice and data network, a wireless local area network (e.g., WiFi or an IEEE 802.xx network), a satellite communications network, a personal area network or other wireless network. The communication network or networks can also include a wired communication network such as a telephone network, an Ethernet network, a local area network, a wide area network such as the Internet, a broadband access network, a cable network, a fiber optic network, or other wired network. The communication devices can include a network edge device, bridge device or home gateway, a set-top box, broadband modem, telephone adapter, access point, base station, or other fixed communication device, a mobile communication device such as an automotive gateway or automobile, laptop computer, tablet, smartphone, cellular telephone, or other communication device.

In an example embodiment, the guided wave communication system700can operate in a bi-directional fashion where transmission device702receives one or more communication signals712from a communication network or device that includes other data and generates guided waves722to convey the other data via the transmission medium725to the transmission device701. In this mode of operation, the transmission device701receives the guided waves722and converts them to communication signals710that include the other data for transmission to a communications network or device. The guided waves722can be modulated to convey data via a modulation technique such as phase shift keying, frequency shift keying, quadrature amplitude modulation, amplitude modulation, multi-carrier modulation such as orthogonal frequency division multiplexing and via multiple access techniques such as frequency division multiplexing, time division multiplexing, code division multiplexing, multiplexing via differing wave propagation modes and via other modulation and access strategies.

The transmission medium725can include a cable having at least one inner portion surrounded by a dielectric material such as an insulator or other dielectric cover, coating or other dielectric material, the dielectric material having an outer surface and a corresponding circumference. In an example embodiment, the transmission medium725operates as a single-wire transmission line to guide the transmission of an electromagnetic wave. When the transmission medium725is implemented as a single wire transmission system, it can include a wire. The wire can be insulated or uninsulated, and single-stranded or multi-stranded (e.g., braided). In other embodiments, the transmission medium725can contain conductors of other shapes or configurations including wire bundles, cables, rods, rails, pipes. In addition, the transmission medium725can include non-conductors such as dielectric pipes, rods, rails, or other dielectric members; combinations of conductors and dielectric materials, conductors without dielectric materials or other guided wave transmission media and/or consist essentially of non-conductors such as dielectric pipes, rods, rails, or other dielectric members that operate without a continuous conductor such as an inner conductor or a conductive shield. It should be noted that the transmission medium725can otherwise include any of the transmission media previously discussed.

Further, as previously discussed, the guided waves720and722can be contrasted with radio transmissions over free space/air or conventional propagation of electrical power or signals through the conductor of a wire via an electrical circuit. In addition to the propagation of guided waves720and722, the transmission medium725may optionally contain one or more wires that propagate electrical power or other communication signals in a conventional manner as a part of one or more electrical circuits.

Referring now toFIG. 8, a block diagram800illustrating an example, non-limiting embodiment of a transmission device is shown. The transmission device701or702includes a communications interface (I/F)805, a transceiver810and a coupler820.

In an example of operation, the communications interface805receives a communication signal710or712that includes data. In various embodiments, the communications interface805can include a wireless interface for receiving a wireless communication signal in accordance with a wireless standard protocol such as LTE or other cellular voice and data protocol, WiFi or an 802.11 protocol, WIMAX protocol, Ultra Wideband protocol, Bluetooth® protocol, Zigbee® protocol, a direct broadcast satellite (DBS) or other satellite communication protocol or other wireless protocol. In addition or in the alternative, the communications interface805includes a wired interface that operates in accordance with an Ethernet protocol, universal serial bus (USB) protocol, a data over cable service interface specification (DOCSIS) protocol, a digital subscriber line (DSL) protocol, a Firewire (IEEE 1394) protocol, or other wired protocol. In additional to standards-based protocols, the communications interface805can operate in conjunction with other wired or wireless protocol. In addition, the communications interface805can optionally operate in conjunction with a protocol stack that includes multiple protocol layers including a MAC protocol, transport protocol, application protocol, etc.

In an example of operation, the transceiver810generates an electromagnetic wave based on the communication signal710or712to convey the data. The electromagnetic wave has at least one carrier frequency and at least one corresponding wavelength. The carrier frequency can be within a millimeter-wave frequency band of 30 GHz-300 GHz, such as 60 GHz or a carrier frequency in the range of 30-40 GHz or a lower frequency band of 300 MHz-30 GHz in the microwave frequency range such as 26-30 GHz, 11 GHz, or 3-6 GHz, but it will be appreciated that other carrier frequencies are possible in other embodiments. In one mode of operation, the transceiver810merely upconverts the communications signal or signals710or712for transmission of the electromagnetic signal in the microwave or millimeter-wave band as a guided electromagnetic wave that is guided by or bound to the transmission medium725. In another mode of operation, the communications interface805either converts the communication signal710or712to a baseband or near baseband signal or extracts the data from the communication signal710or712and the transceiver810modulates a high-frequency carrier with the data, the baseband or near baseband signal for transmission. It should be appreciated that the transceiver810can modulate the data received via the communication signal710or712to preserve one or more data communication protocols of the communication signal710or712either by encapsulation in the payload of a different protocol or by simple frequency shifting. In the alternative, the transceiver810can otherwise translate the data received via the communication signal710or712to a protocol that is different from the data communication protocol or protocols of the communication signal710or712.

In an example of operation, the coupler820couples the electromagnetic wave to the transmission medium725as a guided electromagnetic wave to convey the communications signal or signals710or712. While the prior description has focused on the operation of the transceiver810as a transmitter, the transceiver810can also operate to receive electromagnetic waves that convey other data from the single wire transmission medium via the coupler820and to generate communications signals710or712, via communications interface805that includes the other data. Consider embodiments where an additional guided electromagnetic wave conveys other data that also propagates along the transmission medium725. The coupler820can also couple this additional electromagnetic wave from the transmission medium725to the transceiver810for reception.

The transmission device701or702includes an optional training controller830. In an example embodiment, the training controller830is implemented by a standalone processor or a processor that is shared with one or more other components of the transmission device701or702. The training controller830selects the carrier frequencies, modulation schemes and/or guided wave modes for the guided electromagnetic waves based on testing of the transmission medium725, environmental conditions and/or feedback data received by the transceiver810from at least one remote transmission device coupled to receive the guided electromagnetic wave.

In an example embodiment, a guided electromagnetic wave transmitted by a remote transmission device701or702conveys data that also propagates along the transmission medium725. The data from the remote transmission device701or702can be generated to include the feedback data. In operation, the coupler820also couples the guided electromagnetic wave from the transmission medium725and the transceiver receives the electromagnetic wave and processes the electromagnetic wave to extract the feedback data.

In an example embodiment, the training controller830operates based on the feedback data to evaluate a plurality of candidate frequencies, modulation schemes and/or transmission modes to select a carrier frequency, modulation scheme and/or transmission mode to enhance performance, such as throughput, signal strength, reduce propagation loss, etc.

Consider the following example: a transmission device701begins operation under control of the training controller830by sending a plurality of guided waves as test signals such as pilot waves or other test signals at a corresponding plurality of candidate frequencies and/or candidate modes directed to a remote transmission device702coupled to the transmission medium725. The guided waves can include, in addition or in the alternative, test data. The test data can indicate the particular candidate frequency and/or guide-wave mode of the signal. In an embodiment, the training controller830at the remote transmission device702receives the test signals and/or test data from any of the guided waves that were properly received and determines the best candidate frequency and/or guided wave mode, a set of acceptable candidate frequencies and/or guided wave modes, or a rank ordering of candidate frequencies and/or guided wave modes. This selection of candidate frequenc(ies) or/and guided-mode(s) are generated by the training controller830based on one or more optimizing criteria such as received signal strength, bit error rate, packet error rate, signal to noise ratio, propagation loss, etc. The training controller830generates feedback data that indicates the selection of candidate frequenc(ies) or/and guided wave mode(s) and sends the feedback data to the transceiver810for transmission to the transmission device701. The transmission device701and702can then communicate data with one another based on the selection of candidate frequenc(ies) or/and guided wave mode(s).

In other embodiments, the guided electromagnetic waves that contain the test signals and/or test data are reflected back, repeated back or otherwise looped back by the remote transmission device702to the transmission device701for reception and analysis by the training controller830of the transmission device701that initiated these waves. For example, the transmission device701can send a signal to the remote transmission device702to initiate a test mode where a physical reflector is switched on the line, a termination impedance is changed to cause reflections, a loop back mode is switched on to couple electromagnetic waves back to the source transmission device702, and/or a repeater mode is enabled to amplify and retransmit the electromagnetic waves back to the source transmission device702. The training controller830at the source transmission device702receives the test signals and/or test data from any of the guided waves that were properly received and determines selection of candidate frequenc(ies) or/and guided wave mode(s).

While the procedure above has been described in a start-up or initialization mode of operation, each transmission device701or702can send test signals, evaluate candidate frequencies or guided wave modes via non-test conditions such as normal transmissions or otherwise evaluate candidate frequencies or guided wave modes at other times or continuously as well. In an example embodiment, the communication protocol between the transmission devices701and702can include an on-request or periodic test mode where either full testing or more limited testing of a subset of candidate frequencies and guided wave modes are tested and evaluated. In other modes of operation, the re-entry into such a test mode can be triggered by a degradation of performance due to a disturbance, weather conditions, etc. In an example embodiment, the receiver bandwidth of the transceiver810is either sufficiently wide or swept to receive all candidate frequencies or can be selectively adjusted by the training controller830to a training mode where the receiver bandwidth of the transceiver810is sufficiently wide or swept to receive all candidate frequencies.