In a system of control devices networked with one another via a first network or multiple first sub-networks, and of which at least one is a server-based control device that combines multiple functional units, a grandmaster clock is defined by ascertaining the best clock of the entire network. If the best clock is located in a server-based control device, the distances are ascertained between selected functional units that are suitable as a source of the grandmaster clock and selected active network interfaces that connect the server-based control device to the first network or multiple first sub-networks, and the average distance to all selected network interfaces for each of the selected functional units is determined. That selected functional unit that has the smallest average distance to all selected network interfaces is defined as grandmaster clock for the first network or the first sub-networks.

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 time synchronization system includes a master station (100) and slave stations (200) communicably connected to the master station (100). The master station (100) includes a contention determiner (114) and a time synchronization frame processing unit (113). The contention determiner (114) determines, based on receipt timings of a plurality of first time synchronization frames transmitted from the respective slave stations (200), whether the plurality of first time synchronization frames have a possibility of contention over relay processing. The time synchronization frame processing unit (113) discards, when the contention determiner (114) determines that the plurality of first time synchronization frames have the possibility of the contention, out of first time synchronization frames that have a possibility of mutual contention, a first time synchronization frame received later.

A time synchronization method, apparatus, domain controller, and storage medium are disclosed. The domain controller is mounted in a vehicle and includes a number of SoCs and micro control units. The SoCs and micro control units are respectively, communicatively connected through the controller area network bus and respectively connected to the switch via Ethernet. The switch has external Ethernet interfaces. A main SoC in the number of SoCs has external UART/PPS interfaces and the micro control units have external FlexRay interfaces. The time synchronization method of the domain controller includes any one of the steps of receiving a time service from an external device through the UART/PPS interfaces, receiving a time service from the external device through the switch over the Ethernet interface, or receiving a time service from the external device through the FlexRay interface under a normal operation phase of the vehicle.

In order to provide a transmission device and transmission method with which a response signal for random access preamble transmitted from a preamble transmission device is efficiently transmitted, setting unit in base station sets a first resource candidate group, which enables terminal capable of receiving a latch response transmitted by demodulation reference signal (DMRS) transmission to be selected, and a second resource candidate group, which enables terminal incapable of receiving a latch response transmitted by DMRS transmission but capable of receiving a latch response transmitted by cell-specific reference signal (CRS) transmission to be selected. Control unit selects DMRS transmission as the latch response transmission method when a resource in which latch preamble has been received is included in the first candidate group, but selects CRS transmission as the latch response transmission method when the resource is included in the second resource candidate group.

In one embodiment, a method comprises receiving, by a network device, one or more advertisement messages comprising timing information describing a quality of a network clock that is originated by a master clock device at a root of a directed acyclic graph (DAG); the network device executing an objective function for the DAG providing an optimized loopless time topology for the network clock, synchronized to the master clock device, based on the timing information; and the network device attaching to a parent device in the DAG based on the objective function, for optimized generation of the network clock by the network device.

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 method and a structure for determining a global clock among systems are disclosed. When a standardized time reference is required among systems, a reference clock source may transmit a calibration signal, and a transmitting time T.sub.d (0) may be recorded. Each system may respectively record an arrival time T.sub.a (n), transmit a return signal to a signal recording unit of the reference clock source, and record a transmitting time T.sub.b (n), after receiving the calibration signal. Similarly, because of different distances, the signal recording unit may record arrival times T.sub.d (n) of the return signals subsequently, and determine time delays Delay (n) between systems and the reference clock source respectively. When all the systems are required to have a completely standardized time reference, a corresponding Delay (n) may be acquired and transmitted to each system. Each system may determine zero deviations T.sub.c (n) of various local clocks from the reference clock source, and take T.sub.c (n) as a correction parameter to correct its own system clock, so that the local clocks of all the systems have a completely standardized time reference.

In order to provide a transmission device and transmission method with which a response signal for random access preamble transmitted from a preamble transmission device is efficiently transmitted, setting unit in base station sets a first resource candidate group, which enables terminal capable of receiving a latch response transmitted by demodulation reference signal (DMRS) transmission to be selected, and a second resource candidate group, which enables terminal incapable of receiving a latch response transmitted by DMRS transmission but capable of receiving a latch response transmitted by cell-specific reference signal (CRS) transmission to be selected. Control unit selects DMRS transmission as the latch response transmission method when a resource in which latch preamble has been received is included in the first candidate group, but selects CRS transmission as the latch response transmission method when the resource is included in the second resource candidate group.

Systems and methods for digital synthesis of an output signal using a frequency generated from a resonator and computing amplitude values that take into account temperature variations and resonant frequency variations resulting from manufacturing variability are described. A direct frequency synthesizer architecture is leveraged on a high Q resonator, such as a film bulk acoustic resonator (FBAR), a spectral multiband resonator (SMR), and a contour mode resonator (CMR) and is used to generate pristine signals.