Abstract: A user terminal according to one aspect of the present disclosure includes: a transmitting section that transmits an uplink shared channel by applying a precoder; and a control section that specifies a number of ports used to determine the precoder when a Sounding Reference Signal (SRS) resource is not configured. According to one aspect of the present disclosure, even when an SRS resource is not configured, it is possible to appropriately determine a precoder of a UL signal.

Abstract: A receiver for a serial data link, including an analog front end (AFE) including a continuous-time linear equalizer (CTLE) configured to receive an input signal from a transmitter, the CTLE including a first output node; a second output node; a plurality of programmable tail current sources configured to adjust a direct current (DC) offset between the first output node and the second output node; and a calibration circuit including: a slicer configured to output a difference between a first average output voltage corresponding to the first output node and a second average output, voltage corresponding to the second output node; and a calibration counter configured to increment or decrement an offset count based on the difference, wherein the plurality of programmable tail current sources are adjusted based on a value of the offset count.

Abstract: A signal detection unit detects, from a baseband signal of a received radio wave, two types of fixed signal sections that have different communication information and are present in sufficiently shorter time than a time period in which influence of fading fluctuates, and designate the detected two types of fixed signal sections as an information-1 section and an information-2 section. An information-1 section signal processing unit clips the information-1 section from the baseband signal, and performs Fourier transform on the clipped information-1 section. An information-2 section signal processing unit clips the information-2 section from the baseband signal, and performs Fourier transform on the clipped information-2 section. A feature value computation unit computes a feature value, based on an output of the information-1 section signal processing unit and an output of the information-2 section signal processing unit.

Abstract: The present application relates to an adaptive PAM4 decision feedback equalization circuit, including a decision feedback equalization main circuit and an adaptive circuit. The main circuit includes an adder, a first decision device, a second decision device, a third decision device, a first delay unit group, a second delay unit group, a third delay unit group, a decoder, and a DSP coefficient table; the adaptive circuit includes an eye pattern monitoring module and an adaptive module; and the adaptive module includes a comparison unit, a delay unit, and a coefficient regulation and control unit.

Abstract: Embodiments of apparatus and method for transition smoothing implementation on a stream of data are disclosed. In an example, a system on chip (SoC) for wireless communication includes a digital front-end. The digital front-end is configured to obtain a stream of data having one carrier or multi-carriers. The stream of data is divided into a plurality of blocks. The digital front-end is also configured to adjust a gain of the stream of data based on a predetermined frequency corresponding to a length of each of the plurality of blocks. The digital front-end is also configured to append a ramp-down tail sequence to a first block of the stream of data after a last sample of the first block, and generate a ramp-up head sequence for a second block immediately after the first block, based on a head sequence of the second block.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive data encoded based on a multi-level balanced code, codewords of the multi-level balanced code being selected based on a finite number of multiple sum values, corresponding to all constellation symbol sequences in the multi-level balanced code. The UE may receive a superimposed pilot (SIP) using communication resources occupied by the data. The UE may estimate one or more channel parameters based on the SIP and the multi-level balanced code. Numerous other aspects are described.

Abstract: Disclosed is a modulation method for modulating n-bit data (n=p+q+r). The modulation method includes forming a time difference between a data impulse and a sync impulse to correspond to p-bit data, modulating the amplitude of the sync impulse to correspond to q-bit data and modulating the amplitude of the data impulse to correspond to r-bit data, and combining the sync impulse and the data impulse. As an example, n may be equal to p+q+r.

Abstract: Embodiments provide a data receiver, the data receiver being configured to receive a signal including a sequence of N bits so as to obtain a reception signal, wherein N is a natural number greater than or equal to eight, N?8, wherein the data receiver is configured to sample the reception signal with a sampling rate that corresponds, with an intentional deviation of up to 2/N, to one sample value per bit of the sequence of N bits so as to obtain a sequence of received bits, wherein the data receiver is configured to correlate the sequence of received bits with K different sequences of N-1 reference bits so as to obtain K partial correlation results, wherein K is smaller than or equal to N-1 and greater than or equal to three, N-1?K?3.

Abstract: Embodiments of the present application provide a reference signal transmission method, a device, and a system. The method includes: determining, by a first device, at least one reference signal generation sequence corresponding to at least one frequency-domain resource group that is on a symbol carrying a reference signal and that is used to send the reference signal, where one frequency-domain resource group is corresponding to one reference signal generation sequence; and generating, by the first device, the reference signal based on the at least one reference signal generation sequence, and mapping the reference signal to a time-frequency resource whose time domain is the symbol and whose frequency domain is the at least one frequency-domain resource group.

Abstract: This application proposes multi-beam antenna systems using spherical lens with high isolation between antenna ports and compatible to 2×2, 4×4, 8×8 MIMO transceivers. Several compact multi-band multi-beam solutions (with wideband operation, 40%+, in each band) are achieved by creating dual-band radiators movable on the track around spherical lens and by placing of lower band radiators between spherical lenses. By using of secondary lens for high band radiators, coupling between low band and high band radiators is reduced. Beam tilt range and side lobe suppression are improved by special selection of phase shift and rotational angle of radiators. Resultantly, a wide beam tilt range (0-40 degree) is realized in proposed multi-beam antenna systems. Each beam can be individually tilted. Based on proposed single- and multi-lens antenna solutions, cell coverage improvements and stadium tribune coverage optimization are also achieved, together with interference reduction.

Abstract: The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). According to various embodiments of the disclosure, an apparatus of a terminal in a wireless communication system is provided. The apparatus includes at least one transceiver, and at least one processor configured to be operatively connected to the at least one transceiver, wherein the at least one processor may be configured to: obtain first synchronization of a first carrier that is in synchronization, determine second synchronization of a second carrier that is out of synchronization based on the first synchronization, and perform communication based on the second synchronization.

Abstract: Novel tools and techniques are provided for implementing error detection in a network, and, more particularly, to methods, systems, and apparatuses for implementing error and/or fault detection in a network and/or media stream and providing options to address the error and/or fault in the network and/or media stream. In various embodiments, a computer might detect an error in a first network and send a notification indicating that the error has occurred. The notification might contain one or more options to address the error in the first network. The computer, a user device, a service provider device, or a content provider device might receive and display the notification containing the one or more options. The computer, the user device, the service provider device, or the content provider device might then select at least one of the one or more options to address the error in the first network.

Abstract: Embodiments of the present disclosure include a processing device that, responsive to detecting an unavailability of a first node device of a plurality of node devices of a network, activates a proxy device to correspond to the first node device, detects a consensus operation among the plurality of node devices, wherein the consensus operation comprises a plurality of vote transmissions within the network, and controls the proxy device to provide a proxy vote transmission as part of the consensus operation.

Abstract: A method includes executing, on a processor of a computing device, instructions that cause the computing device to perform operations. The operations include executing, on a processor of a computing device, instructions that cause the computing device to perform operations. The operations include receiving site features associated with a communication site and receiving event features associated with a potential outage-causing event. A classifying engine is employed to generate an impact metric indicating an effect on the communication site from the potential outage-causing event based on the site features and the event features.

Abstract: Devices, methods, and systems that provide transmitting of messages between different units of a multi-unit system in response to instantiated multi-unit transactions. For example, a method may include: identifying, by a first unit of a multi-unit system of computing devices, an event has occurred that triggers initiation of a transaction; generating, by the first unit, a transaction identifier associated with the transaction, the transaction identifier comprising a unit identifier of the first unit and an application identifier of an application associated with the event; and transmitting, from the first unit and to a second unit of the multi-unit system, the transaction identifier as part of an inter-unit message.

Abstract: This disclosure describes techniques for diagnosing a presence or malfunction of a network node. In an example method, a first network node receives an indication of a diagnostic transmission originating from a second network node. The second network node further receives a forwarded transmission corresponding to the diagnostic transmission. The first network node diagnoses at least one of a presence or a malfunction of an intermediary node between the first network node and the second network node based on at least one of the indications of the diagnostic transmission or the forwarded transmission.

Abstract: A method for handling large-scale host failures on a cloud platform includes: configuring a corresponding failed host queue for each host group; setting initial priority values and evacuation count thresholds for cloud hosts; arranging failed hosts in failed host queues according to priorities of the failed hosts, and arranging the cloud hosts in the failed hosts according to priority values of the cloud hosts; handling, by the host group, the failed hosts the cloud hosts and in the corresponding failed host queue according to an arrangement order; when evacuation of a cloud host fails, re-determining a priority value of the cloud host; detecting evacuation capability of the host group corresponding to each failed host queue, and disabling a failed host queue having poor evacuation capability; arranging failed hosts in the disabled failed host queue into remaining failed host queues; and enabling a failed host queue meeting a condition.

Abstract: A centralized application management computing system is described that is configured to generate digital dog tag files for local storage on each computing device of a plurality of computing devices (e.g., data center servers) within the enterprise network. The computing system is configured to periodically retrieve, from one or more sources within the enterprise network, application information for one or more applications hosted on a given computing device of the plurality of computing devices. The computing system is configured to periodically generate, based on the application information, a digital dog tag file for the given computing device that includes recovery information for the one or more applications hosted on the given computing device. The computing system is further configured to send the digital dog tag file for local storage at a predefined location on the given computing device.

Abstract: In general, embodiments relate to a method for managing traffic flow along a path between network devices. The method includes initiating, by an end-point network device, monitoring of the path, wherein the end-point network device transmits packets to a target network device over the path, detecting after the initiating, by the end-point network device, that at least a portion of the path has failed, wherein the portion of the path that has failed is external to the end-point network device, in response to the detecting, identifying which portions of network device hardware in the source network device need to be updated to redirect the packets from the end-point network device to the target network device to take a second path, and updating the identified portions of the network device hardware.

Abstract: Disclosed are a method and an apparatus for beam failure recovery in a communication system. The method for beam failure recovery includes the steps of: searching for a plurality of candidate beams when a beam failure is detected; transmitting a beam failure recovery request signal to a base station by using beam #1 of the plurality of candidate beams; receiving a beam failure recovery response signal in response to the beam failure recovery request signal via beam #1 from the base station; and transmitting an SR requesting a resource for transmission of multi-beam setting information to the base station, wherein the multi-beam setting information includes indexes of one or more beams excluding beam #1 of the plurality of candidate beams. Therefore, performance of the communication system can be improved.

Abstract: Apparatus, device, methods and system relating to a vehicular telemetry environment for identifying in real time unpredictable network communication faults in network zones based upon pre-processed raw telematics big data logs that may include gps data and an indication of vehicle status data, and supplemental data that may further include location data and network data.

Abstract: A storage gateway serves as an interface between processes on a customer network and a service provider. The storage gateway is located on-premise with the customer processes. To customer processes, it appears that data is stored locally. However, the storage gateway interfaces with a remote storage service to store the data. For cached gateways, the primary data store is a remote data store, while frequently accessed data may be locally cached by the gateway. Reads may be satisfied from the local cache or from virtual data storage; writes are handled so as to appropriately update data blocks in the local cache and/or in virtual data storage. For shadowing gateways, the primary data store is the local data store; reads are passed through to a local data store, and writes are shadowed to virtual data storage as well as being sent to local data store.

Abstract: The present disclosure describes systems, methods, and computer-readable storage media implementing techniques for providing split control of an execution environment. According to aspects of the disclosure, a first entity may be configured to exert control over presentation related aspects (e.g., the look and feel) of services provided by a second entity, while the second entity may exert control over backend processing and execution of the services. To facilitate the different portions of the split control, one or more servers may be configured to provide a first execution layer, a second execution layer, and a second execution layer control panel. The first execution layer may perform operations for executing the provisioning of the service.

Abstract: Systems and methods include obtaining measurements from a Wi-Fi network that includes i) a plurality of access points interconnected to one another and at least one connected to a gateway, and ii) a plurality of Wi-Fi client devices that each connect to an access point of the plurality of access points; learning usage patterns in the Wi-Fi network through analysis with one or more machine learning algorithms; and providing a configuration to the Wi-Fi network based on the learned usage pattern where the configuration includes a topology of the plurality of access points.

Abstract: An Internet of Things (IoT) platform is disclosed which includes: a network; a plurality of IoT servers coupled together and serviced by the network; a plurality of IoT managers coupled to each other and to the plurality of IoT servers; and a plurality of IoT devices electrically coupled to the plurality of IoT managers, wherein the IoT servers and the IoT managers of the present invention are operable to configure a plug-and-play and point to multipoint communication environment where the plurality of IoT devices, the plurality of IoT servers, and the plurality of IoT managers communicate with one another in a plug-and-play manner and in a point to multipoint manner regardless of their physical connections, industrial standards, and communication protocols.

Abstract: An Internet of Things (IoT) system is disclosed which includes: a network; a plurality of IoT servers coupled together and serviced by the network; a plurality of IoT agents coupled to each other and to the plurality of IoT servers; and a plurality of IoT devices electrically coupled to the plurality of IoT agents, wherein the IoT servers and the IoT agents further includes a deep reinforcement neural network operative to generate an action map {at} so as to satisfy an arg ? ? max ? a t ? Q ? ( s , a , ? ) wherein Q(s,a)=E[Rt|(s, a)].

Abstract: A computing system implementing an application service can determine, from a network dataset, that a network latency for a common network service provider crosses an upper latency threshold. Based on this determination, the system can determine a subset of the computing devices that utilize the common network service provider, and transmit a set of configuration signals to the subset of computing devices. The set of configuration signals can modify a set of default application configurations of a designated application to compensate for the network latency.

Abstract: A system for coordinated management of Internet of Things (IoT) devices to minimize power consumption and network congestion is provided. A mobile device designated as local group management device (LGMD) identifies a group of IoT devices that are configured to access a network. The mobile device receives information regarding an upcoming event involving the group of IoT devices. The mobile device generates usage knowledge specifying the group of IoT devices, a location, and a time associated with the upcoming event. The mobile device receives configuration update data that are generated based on the usage knowledge for scheduling operations of the group IoT devices. The mobile device delivers the configuration update data to the group of IoT devices.

Abstract: A device may receive information identifying a plurality of requests and identifying a plurality of targets for the plurality of requests. The device may generate respective routes for the plurality of targets, where a route, of the respective routes, for a target, of the plurality of targets, identifies a set of transformations to be applied to a corresponding request of the plurality of requests. The device may apply the respective routes to the plurality of requests to generate processed requests, and may communicate with at least one of the plurality of targets based on the processed requests. The device may receive results based on communicating with the at least one of the plurality of targets, wherein the results are based on the processed requests, and may provide information based on the results.

Abstract: In general, techniques are described for determining reorder commands for remote reordering of policy rules. A device management system comprising a memory, a processor, and an interface may be configured to perform the techniques. A memory may store a currently configured policy for a managed network device and an updated policy for the managed device. The processor may determine a longest increasing subsequence (LIS) between a source list comprising the plurality of policy rules in a first ordering and a destination list of the plurality of policy rules in a second ordering. The processor may generate, based on the LIS, one or more policy configuration commands for the managed network device that direct the managed network device to conform the currently configured policy to the updated policy. The interface may output the one or more policy configuration commands to the managed network device.

Abstract: A network may include multiple allocations. The allocations may include: a first allocation encompassing central infrastructure, such as central office servers, data centers, or other core infrastructure; an second allocation encompassing gateway elements or other central consumer premises network infrastructure; and a third allocation encompassing nodes, such as client devices, terminals, or other nodes. A virtualization management engine may coordinate resources from the various allocations to support virtual functions distributed over multiple allocations of the network. The virtualization management engine may determine the distribution across the allocations for the virtual functions. The virtualization management engine may be implemented as a virtual function and be distributed across the allocations of the network.

Abstract: Some embodiments provide a network management system for managing a logical network that spans multiple physical sites. The network management system includes a global network manager for receiving global logical network configuration data for the multiple physical sites. The network management system includes, at each of the physical sites, (i) a local network manager for receiving a logical network configuration for the physical site from the global network manager and (ii) a set of central controllers for distributing logical network configuration data to computing devices that implement the logical network at the physical site.

Abstract: Techniques and solutions are provided for determining changes to networks formed from network objects. Changes to network objects, such as addition or deletion operations are received and associated with timestamps. Last data changes for respective network objects are determined, including a last data change for a particular type associated with a respective networked object, where a networked object may be concurrently associated with a plurality of types. A first network object is removed from a first network, and contributions of the first network object to edges in the first network are removed. A second network object is associated with an addition operation and at least one edge is determined that connects the second network object and a third network object. Sets of disconnected network objects are determined. Network objects are associated with an identifier identifying a network that includes a respective network object.

Abstract: Various examples of systems and methods are described herein in which multiple intelligent electronic devices (IEDs) are connected in a network. A software-defined network (SDN) controller may include a rule subsystem, a test mode subsystem, a packet inspection subsystem, and a validation subsystem. The rule subsystem may define a plurality of flow rules. A test mode subsystem may operate the SDN in a testing mode. A packet insertion subsystem may insert test packets within the SDN while the SDN is in the testing mode. The validation subsystem may validate or fail each flow rule depending on how the various test packets are handled.

Abstract: Example device management systems and methods are described. In one implementation, techniques identify a first plurality of devices communicating using a first rate plan associated with a carrier. The techniques further identify a second plurality of devices communicating using a second rate plan associated with the carrier. The techniques analyze the first rate plan and the second rate plan based on data usage. The techniques then identify at least one recommended rate plan change for at least one of the first plurality of devices or the second plurality of devices based on the analysis.

Abstract: A method for managing data migration includes: obtaining a confidence level of a predicted failure state of a storage component (SC) of a source device; making a first determination that the confidence level exceeds a minimum threshold; making, based on the first determination, a second determination that a high priority network slice of a network exists; mapping data stored in the SC to the high priority network slice; migrating the data to a target device; after migrating the data to the target device: obtaining a confidence level of a predicted failure state of a processing component (PC); making a third determination that the confidence level of the predicted failure state of the PC exceeds a maximum threshold; mapping, based on the third determination, non-migrated data stored in the source device to the high priority network slice; and migrating the non-migrated data to the target device.

Abstract: A method includes: receiving protocol event data from a plurality of probes within the telecommunication system; determining a most probable cause of a call event from the protocol event data; applying the most probable cause to a trained machine learning algorithm that includes the most probable cause as its input and a telecommunication system score as its output; and in response to an output score from the trained machine learning algorithm, performing a corrective action for a plurality of network users that are expected to be affected by the most probable cause.

Abstract: Techniques are disclosed for a user interface for displaying a topology representation of infrastructure of a 5G Radio Access Network (RAN), such as an Open Radio Access Network (O-RAN) 5G infrastructure. For example, a computing system displays, via a user interface, first icons, each icon of the first icons representing first components providing Level-1 functionality for the O-RAN 5G infrastructure, such as non-real-time RAN Intelligent Controllers (RICs). The computing system receives, via the user interface, a selection of a first icon of the first icons. In response to the selection, the computing system displays, via the user interface, second icons, each icon of the second icons representing second components managed by a component of the first components corresponding to the selected first icon. The second components provide Level-2 functionality for the O-RAN 5G infrastructure, such as near-real-time RICs.

Abstract: A service data management method and apparatus for service building blocks (SBB), a device and a storage medium are provided, and a service data setting interface is extended. When service data needs to be set, the service data is received through the service data setting interface, and service data to be set is added into a service data set of a service corresponding to service identification information according to the service identification information and the service data to be set in the service data setting instruction. When it is detected that an SBB needs to be configured with the service data, service data corresponding to the SBB in the service data set corresponding to the SBB is directly configured for the SBB, i.e., the set service data takes effect immediately and is able to be called by the corresponding the SBB in real time.

Abstract: Systems and methods include establishment of a first database session with a first database user, determine first session variable values associated with the first database session, the first session variable values including a first tenant value, determine a first workload class based on the first tenant value and on zero or more of the other first session variable values, the first workload class including first parameter values specifying first resource consumption limits, and manage resource consumption of the first database session based on the first parameter values.

Abstract: A system for managing system performance of one or more customer systems, the system comprising: a memory for storing one or more objects; a gateway communicatively coupled to a customer system, the customer system separated from a wide area network by a firewall, and including one or more computer systems and databases within a customer premises; one or more processors communicatively coupled to the memory and the gateway, the firewall being disposed between the gateway and the one or more processors, the one or more processors and the gateway configured to receive data related to speed, performance of the customer system over a first period of time, receive data related to speed and performance of the customer system over a second period of time, and provide one or more displays related to comparisons of speed and performance over the first and second periods of time based on a user input.

Abstract: A device receives a communication associated with a support issue encountered by a user, and receives information identifying one or more self-support actions performed by the user in relation to the support issue. The device assigns the communication to a position in a support queue. The support queue includes information identifying positions of other communications received from other users, when the other communications are received, and self-support actions performed by the other users. The device associates the information identifying the one or more self-support actions with information identifying the position of the communication, and applies respective weights to the one or more self-support actions. The device generates a score for the communication based on applying the respective weights, and modifies the position of the communication based on the score. The device performs one or more actions based on modifying the position of the communication.

Abstract: A generation identifier is employed with various systems and methods in order to identify situations where a workload has been reassigned to a new node and where a workload is still being processed by an old node during a failure between nodes. A master node may assign a workload to a worker node. The worker node sends a request to access target data. The request may be associated with a generation identifier and workload identifier that identifies the node and workload. At some point, a failure occurs between the master node and worker node. The master node reassigns the workload to another worker node. The new worker node accesses the target data with a different generation identifier, indicating to the storage system that the workload has been reassigned. The old worker node receives an indication from the storage system that the workload has been reassigned and stops processing the workload.

Abstract: Techniques are described for generating an end-to-end distributed trace in connection with a cloud or datacenter environment. In one example, a server obtains target application telemetry data and external telemetry data associated with one or more correlation identifiers included in one or more network communications provided to a target application in the cloud or datacenter environment. The server aggregates the target application telemetry data and the external telemetry data based on the one or more correlation identifiers to generate an end-to-end distributed trace associated with the one or more network communications.

Abstract: Example implementations relate to changing a status of a device responsive to detecting an anomaly. A traffic pattern of a device may be monitored across a network. It may be determined that the monitored traffic pattern deviates from an expected traffic pattern of the group of devices by a threshold. Responsive to determining that the devices deviates from the expected traffic pattern, packet data transmitted by the device may be inspected. It may be determined that the inspected packet data transmitted by the device is anomalous. The status of the device may be changed responsive to determining that the packet data transmitted by the device is anomalous.

Abstract: Described are embodiments of a method for performance measurement of a communication device. The method comprises: executing active probing by a communication device coupled to another communication device via a network forming a communication link; reading operational data associated with the communication link in response to executing active probing; and measuring performance, by the communication device, of the communication link with reference to the communication link, the performance measured according to the read operational data.

Abstract: In an estimation system 100 including an addition device 1 and an estimation device 3, the addition device 1 includes a storage section 11 which stores address information of each interface of one of at least two network devices connected to each other, and a transmission section 16 which transmits, at different times, a PING packet which is output to the other network device and is then returned to the one of the network devices to each interface of the one of the network devices by using the address information of the interface read from the storage section, and the estimation device 3 includes an estimation section 34 which compares, for each time, time-series data of a data amount of each interface of the one of the network devices which includes a data amount of the PING packet and time-series data of a data amount of each interface of the other network device which includes the data amount of the PING packet, and calculates a combination of the interfaces of which the data amounts at each time match eac

Abstract: Systems, methods, and computer-readable media are disclosed for validating multiple paths used for routing network traffic in a network. In one aspect, a network controller can identify one or more intermediate nodes on each of multiple paths in a network, wherein the multiple paths begin at a first network node and end at a last network node. The network controller can further generate a data packet with a label at the first network node, forward the test data packet from the first network node, along each of the one or more intermediate nodes, to the last network node, and perform a data plane validation process for validating packet forwarding from the first network node to the last network node based on the label(s) by determining if a number of the multiple paths equals to a number of packets received at the last network node.

Abstract: Metadata indicating that a virtual traffic hub enabling connectivity between a plurality of isolated networks has been established is stored. A determination is made that a first entry of a first isolated network attached to the hub is to be represented in a second routing table of a second isolated network attached to the hub, e.g., to enable network packets originating at resources of the second isolated network to be transmitted via the hub to the first isolated network. A new entry corresponding to the first entry is included in the second routing table.

Abstract: An apparatus for analyzing a network according to an embodiment includes a receiving module configured to receive, from a cloud service, information on one or more resources included in the cloud service and information on a network environment of the one or more resources, a topology generation module configured to derive a network topology of the cloud service by using the information on the resources and the information on the network environment, and an analysis module configured to derive, from the network topology, a communication possible path of each of the one or more resources and one or more communication allow policies in the communication possible path.