Systems and methods include receiving, values of one or more first external time variables from a first external node and values of one or more second external time variables from a second external node. The values of one or more local time variables of the local node are adjusted based at least upon the values of the one or more first external time variables and the values of the one or more second external time variables.

Techniques that provide link auto-negotiation between a radio equipment controller (REC) and a radio equipment (RE) are described herein. In one embodiment, a method includes performing, by a proxy master, a Common Public Radio Interface (CPRI) Layer 1 (L1) link auto-negotiation with a RE to achieve a L1 synchronization between the proxy master and the RE at a link bit rate; communicating the link bit rate from the proxy master to a proxy slave; performing, by the proxy slave, a CPRI L1 link auto-negotiation with a REC to determine whether a L1 synchronization between the proxy slave and the REC is achieved, wherein if the L1 synchronization is achieved, the link bit rate is a common matching link bit rate achieved; and upon the common matching link bit rate being achieved, establishing a CPRI link between the REC and the RE using the common matching link bit rate.

Techniques associated with link establishment in a fronthaul network are described herein. In one embodiment, a method includes receiving, by a proxy node, a Common Public Radio Interface (CPRI) bit stream transmitted by a radio equipment controller, wherein the CPRI bit stream is transmitted within a transmit time interval of the radio equipment controller; and fast-sampling, by the proxy node, the CPRI bit stream to determine whether a hyper frame number synchronization with the radio equipment controller at a common matching link bit rate is achievable, wherein the fast-sampling comprises attempting to decode the received CPRI bit stream and achieve the hyper frame number synchronization for each of a plurality of link bit rates configured for a fast-sampling time period during at least one fast-sampling time interval configured for the proxy node.

Techniques that provide link establishment between a radio equipment controller (REC) and a radio equipment (RE) in a fronthaul network are described herein. In one embodiment, a method includes performing, Common Public Radio Interface (CPRI) Layer 1 (L1) link auto-negotiation operations to establish a CPRI link between the REC and RE. A proxy slave may achieve a hyper frame number (HFN) synchronization with the REC at a link bit rate for a first CPRI bit stream and communicate the first CPRI bit stream and the link bit rate to a proxy master. The proxy master may communicate a second CPRI bit stream to the proxy slave to transmit to the REC. The L1 link auto-negotiation operations are completed and CPRI link is established between the REC and the RE when the REC achieves a HFN synchronization for the second CPRI bit stream.

A communication system according to one aspect of the present disclosure is a communication system in which a plurality of communication devices are connected to a network. The plurality of communication devices include a time master including a master clock that manages time of the communication system and a plurality of time slaves each of which includes a slave clock time-synchronized with the master clock. Each of the plurality of time slaves includes a synchronization unit that performs time synchronization with another communication device connected adjacent to a master side on the network and a communication unit that notifies the time master of time synchronization information indicating time synchronization accuracy of the own device obtained by the synchronization unit.

In an example embodiment disclosed herein, a first clock is allowed to synchronize with a second clock as long as the time difference between the first and second clocks is less than a predefined limit. If the time difference between the clocks is not less than the predefined limit, the first clock does not synchronize with the second clock until a predefined activity has occurred.

In vehicular communication networks, reliable delivery of safety messages is crucial and any transmission collision is to be avoided. A method based on time division multiple access scheme is described. An extra layer is provided to manage and schedule transmission of safety messages. The extra, message broadcasting handling layer (MBH layer) is provided between safety applications and medium access control (MAC) layer. Safety messages generated and received from safety application is spooled in the MBH layer and scheduled by the MBH layer for delivery to the MAC layer for broadcasting. A device to implement the method is also described.

The embodiments are an aircraft time synchronization system and method. The system comprises: a first communication module and a second communication module, wherein data transmission is performed between the first communication module and the second communication module via a communication line, and an I/O interface of the first communication module is connected to the I/O interface of the second communication module via an interruption signal line; the first communication module sends the data information to the second communication module via the communication line, and at the same time sends the triggered interruption signal to the second communication module via the interruption signal line; the second communication module performs time synchronization with the first communication module based on the communication time difference and system time difference with the first communication module determined according to the receiving time of the data information and interruption signal and the sending time.

Apparatuses, computer readable media, and methods for uplink and downlink sounding for wireless networks are disclosed. An apparatus of a wireless device is disclosed. The apparatus comprising processing circuity configured to: encode a trigger frame for sounding (TF-S), the TF-S comprising an indication of whether a sounding is for uplink (UL) sounding or (DL) sounding, and the TF-S comprising an indication of stations to participate in the UL sounding or the DL sounding; and configure the wireless device to transmit the TF-S to the stations. The processing circuitry may be further configured to: if the sounding is for the DL sounding, encode a null data packet announcement (NDP-A), encode a null data packet (NDP), configure the wireless device to transmit the NDP-A, and configure the wireless device to transmit the NDP.

Systems and methods for one-way time transfer using physical layer signaling are disclosed herein. According to some examples, a method includes generating timing information based on a clock of a transmitting device, where the timing information comprises a timestamp and metadata. The method further includes generating a preamble of a frame, where the preamble includes the timestamp and the metadata of the timing information. The method also includes forming a frame, where the frame comprises a bootstrap, the preamble, and a payload, and transmitting the frame to a receiver device. The one-way time transfer systems and methods of this disclosure can serve mobile devices that entail quick and reliable establishment of a clock.