Abstract:
Systems and methods for routing protocols for power line communications (PLC) are described. In some embodiments, a method performed by a PLC device, such as a PLC meter, may include selecting one or more transmit sub-bands on which to transmit frames, where the transmit sub-bands comprise groups of carrier frequencies. The PLC device then generates a frame comprising a tone map that indicates which transmit sub-bands are used to carry data for the frame. The tone map using two bits per transmit sub-band to indicate a status of each transmit sub-band. The PLC device then transmits the frame on the selected transmit sub-bands. A resolution bit and a mode bit may be used to provide additional information about the transmit sub-bands, such as an amount of power adjustment that has been applied to carrier frequencies and whether dummy bits are transmitted on unused carrier frequencies.
Abstract:
Embodiments of methods and systems for supporting coexistence of multiple technologies in a Power Line Communication (PLC) network are disclosed. A long coexistence preamble sequence may be transmitted by a device that has been forced to back off the PLC channel multiple times. The long coexistence sequence provides a way for the device to request channel access from devices on the channel using other technology. The device may transmit a data packet after transmitting the long coexistence preamble sequence. A network duty cycle time may also be defined as a maximum allowed duration for nodes of the same network to access the channel. When the network duty cycle time occurs, all nodes will back off the channel for a duty cycle extended inter frame space before transmitting again. The long coexistence preamble sequence and the network duty cycle time may be used together.
Abstract:
Transmission over a communication channel using carrier sense multiple access collision avoidance (CSMA/CA) may be performed by determining for each frame if the communication channel is busy after a backoff time proportional to a randomly generated number within a contention window (CW). When the channel is not busy, a frame of data may be transmitted. When the channel is busy, the device may periodically determine if the communication channel is busy after subsequent backoff times. The value of CW is adjusted for each subsequent backoff time using a fairness protocol, in which the value of CW is increased until the value of CW reaches a maximum CW value; and then the value of CW is held until a fairness number of backoff repetitions reaches a fairness threshold; then the value of CW is reduced incrementally until the value of CW reaches a minimum CW value.
Abstract:
Embodiments of the invention provide systems and methods for a cipher then segment approach in a Power Line Communication (PLC). A node or device generates frames to be transmitted to a destination node in the PLC network. A processor in the node is configured to generate a data payload comprising data to be sent to the destination node. The processor divides the data payload into two or more payload segments and encrypts the payload segments. The processor creates a frame for each of the encrypted payload segments, wherein each frame comprises a message integrity code. The processor creates a segment identifier for each frame using the message integrity code and an authentication key that is shared with the destination PLC node. The segment identifier is added to each frame.
Abstract:
Systems and methods for implementing data concentrated initiated multicast firmware upgrade in power line communications (PLC) are described. In an illustrative embodiment, a method performed by a PLC device may include forming a group of PLC devices to receive a transmission of a data set, the group being organized according to a hierarchical structure, transmitting the data set to the group of PLC devices, determining whether a PLC device in the lowest level of the hierarchical structure is missing one or more portions of the data set, and retransmitting at least the missing portions of the data set until the lowest level of PLC devices each have the full data set.
Abstract:
Embodiments of methods and systems for transmitting and receiving segmented frames in a Power Line Communication (PLC) network are disclosed. A transmitter sends a first segment using CSMA/CA based on the priority of frame. All the other segments are transmitted using the CFS slot. When an ACK is received, transmitter sends the next segment after CFS. When a NACK is received, the transmitter sends just the last segment after CFS. If no ACK/NACK is received, the transmitter sends the last segment using CSMA/CA. If a NO_EARLIER_SEGMENTS delimiter is received, the transmitter sends the frame starting from the first segment using CSMA/CA. A receiver may send the NO_EARLIER_SEGMENTS delimiter when no earlier segments are in a receive buffer for reassembly. If the receiver is expecting to continue the reassembly of another frame when a segment is received, the receiver may transmit a BUSY_REASSEMBLY delimiter.
Abstract:
Embodiments of methods and systems for supporting coexistence of multiple technologies in a Power Line Communication (PLC) network are disclosed. A long coexistence preamble sequence may be transmitted by a device that has been forced to back off the PLC channel multiple times. The long coexistence sequence provides a way for the device to request channel access from devices on the channel using other technology. The device may transmit a data packet after transmitting the long coexistence preamble sequence. A network duty cycle time may also be defined as a maximum allowed duration for nodes of the same network to access the channel. When the network duty cycle time occurs, all nodes will back off the channel for a duty cycle extended inter frame space before transmitting again. The long coexistence preamble sequence and the network duty cycle time may be used together.
Abstract:
Systems and methods for relative phase detection and zero crossing detection for power line communications (PLC) are described. In some embodiments, both transmit and receive PLC devices detect a zero crossing on an AC mains phase. The devices start a phase detection counter (PDC) by generating a zero crossing pulse within 5% of the actual zero crossing time. When a frame is transmitted, the transmitting device includes a PDC value in the frame control header (FCH). The PDC value corresponds to the start time of the FCH. When the frame is received at the receive PLC device, the receive PLC device measures a local PDC value between the zero crossing and the start of the FCH. The receive device compares the local PDC value to the PDC value in the FCH of the received frame and determines if the devices are on the same phase.
Abstract:
Authentication of a networked device with limited computational resources for secure communications over a network. Authentication of the device begins with the supplicant node transmitting a signed digital certificate with its authentication credentials to a proxy node. Upon verifying the certificate, the proxy node then authenticates the supplicant's credentials with an authentication server accessible over the network, acting as a proxy for the supplicant node. Typically, this verification includes decryption according to a public/private key scheme. Upon successful authentication, the authentication server creates a session key for the supplicant node and communicates it to the proxy node. The proxy node encrypts the session key with a symmetric key, and transmits the encrypted session key to the supplicant node which, after decryption, uses the session key for secure communications. In some embodiments, the authentication server encrypts the session key with the symmetric key.
Abstract:
Systems, methods, and computer program products provide for time critical packet transmission. An electronic device may include a transceiver and a processor that is configured to receive or transmit, via the transceiver, a plurality of packets having respective headers conforming to a layer below a network layer, and the first header of a first packet of the plurality of packets may include a source address and a hop limit field. The packet may be transmitted according to the layer below the network layer, thereby providing a smaller packet.