A method of frequency search and error correction of clock and data recovery circuit, comprising: initializing a frequency search algorithm parameter; processing a frequency error parameter UP/DN signals according to the set algorithm parameter and starting the frequency search, in which, the algorithm accordingly counts the UP/DN signals. When a phase error signal transition occurs, a transition parameter JUMP is accumulated by 1, and an accumulation parameter SUM is obtained and is further judged that whether a frequency search result is to be output. Number of repeating times of verification and threshold parameters are set, accordingly a reset DCRL value is obtained to verifies a frequency locking result and outputs the result. The present invention improves accuracy of UP/DN pulse counting, increases stability and reliability of the frequency locking, avoids a false locking in the frequency locking, and prevents an excessive locking time in the frequency locking, overcomes error judgment of the frequency search caused by a random jitter, and correctly completes the frequency search and locking, avoids failure of the CDR caused by an error frequency locking.

A time synchronization method, a time synchronization sender, a time synchronization receiver and a time synchronization system are provided. The method includes: determining whether at least one parameter causing recalculation of a best master clock (BMC) algorithm changes; in a case where it is determined that the parameter changes, sending a 1588 standard-based Announce message; and in a case where it is determined that the parameter does not change, sending a keep-alive message of the Announce message. In the present disclosure, by distinguishing keep-alive messages from protocol messages, the problem that a CPU system is busy due to the processing of Announce messages is solved, thereby realizing the optimization of the 1588 protocol, and reducing the impact on the CPU.

A time synchronization method, a time synchronization sender, a time synchronization receiver and a time synchronization system are provided. The method includes: determining whether at least one parameter causing recalculation of a best master clock (BMC) algorithm changes; in a case where it is determined that the parameter changes, sending a 1588 standard-based Announce message; and in a case where it is determined that the parameter does not change, sending a keep-alive message of the Announce message. In the present disclosure, by distinguishing keep-alive messages from protocol messages, the problem that a CPU system is busy due to the processing of Announce messages is solved, thereby realizing the optimization of the 1588 protocol, and reducing the impact on the CPU.

Systems and methods are presented that offer significant improvements in the performance of time division duplex (TDD) systems by utilizing an adaptive synchronous protocol. Conventional TDD systems are limited because data is transmitted during discreet and limited intervals of time, and because TDD transceivers may not simultaneously transmit and receive for reasons of insufficiently separated frequencies and limited receiver selectivity. Typically, TDD systems have significant latency due to the time to change from transmission to reception and the propagation delay time. By synchronizing the master nodes and the one or more remotes and by scheduling the traffic loads between these nodes, remote nodes may begin transmitting before the master node is finished with its transmission, and vice versa. This method reduces latency and improves the frame efficiency. Further, the frame efficiency may improve as the distance from the master node to the remote node increases.

Systems and methods are presented that offer significant improvements in the performance of time division duplex (TDD) systems by utilizing an adaptive synchronous protocol. Conventional TDD systems are limited because data is transmitted during discreet and limited intervals of time, and because TDD transceivers may not simultaneously transmit and receive for reasons of insufficiently separated frequencies and limited receiver selectivity. Typically, TDD systems have significant latency due to the time to change from transmission to reception and the propagation delay time. By synchronizing the master nodes and the one or more remotes and by scheduling the traffic loads between these nodes, remote nodes may begin transmitting before the master node is finished with its transmission, and vice versa. This method reduces latency and improves the frame efficiency. Further, the frame efficiency may improve as the distance from the master node to the remote node increases.

Embodiments of this application disclose a data processing method, which can be applied to a clock synchronization network system. The system can correct, based on a clock frequency error or a time error, a data timestamp of a data packet collected by the system in a time period in which there is no reference clock, so that a corrected system time of the data packet is consistent with a reference time. This improves accuracy of data record.

A communication device includes: a plurality of wireless communication sections, each of which is configured to wirelessly receive a signal from another communication device; and a control section configured to select a wireless communication section from which a specific reception time corresponding to an optimum parameter that is a reliability parameter indicating that the specific reception time is most appropriate for a processing target is detected, as a transmission communication section serving as a wireless communication section that transmits a signal from among the plurality of wireless communication sections, and configured to measure a distance between the transmission communication section and the other communication device on the basis of the specific reception time detected from a correlation computation result obtained from signals transmitted/received between the other communication device and the selected transmission communication section.

A communication method determination apparatus includes a comparison unit and an instruction unit. The comparison unit obtains a bit string of a portion of a physical header for synchronization from a wireless frame that includes the physical header for synchronization in which information for synchronization in a physical layer is set and a physical data portion in which data of a higher-level layer than the physical layer is set, and compares the obtained bit string with a bit string pattern specific to a communication method targeted for determination. The instruction unit performs communication method determination processing for determining whether or not the communication method targeted for determination is used for the wireless frame, based on a result of comparison. If it is determined that the communication method targeted for determination is not used for the wireless frame, the instruction unit changes the communication method targeted for determination, instructs the comparison unit to newly obtain a bit string of a portion that follows the obtained bit string, from the physical header for synchronization, and to compare the newly obtained bit string with a bit string pattern specific to the post-change communication method targeted for determination, and performs the communication method determination processing again.

A communication method determination apparatus includes a comparison unit and an instruction unit. The comparison unit obtains a bit string of a portion of a physical header for synchronization from a wireless frame that includes the physical header for synchronization in which information for synchronization in a physical layer is set and a physical data portion in which data of a higher-level layer than the physical layer is set, and compares the obtained bit string with a bit string pattern specific to a communication method targeted for determination. The instruction unit performs communication method determination processing for determining whether or not the communication method targeted for determination is used for the wireless frame, based on a result of comparison. If it is determined that the communication method targeted for determination is not used for the wireless frame, the instruction unit changes the communication method targeted for determination, instructs the comparison unit to newly obtain a bit string of a portion that follows the obtained bit string, from the physical header for synchronization, and to compare the newly obtained bit string with a bit string pattern specific to the post-change communication method targeted for determination, and performs the communication method determination processing again.

Communication systems and methods in accordance with various embodiments of the invention utilize modulation on zeros. Carrier frequency offsets (CFO) can result in an unknown rotation of all zeros of a received signal's z-transform. Therefore, a binary MOCZ scheme (BMOCZ) can be utilized in which the modulated binary data is encoded using a cycling register code (e.g. CPC or ACPC), enabling receivers to determine cyclic shifts in the BMOCZ symbol resulting from a CFO. Receivers in accordance with several embodiments of the invention include decoders capable of decoding information bits from received discrete-time baseband signals by: estimating a timing offset for the received signal; determining a plurality of zeros of a z-transform of the received symbol; identifying zeros from. the plurality of zeros that encode received bits by correcting fractional rotations resulting from the CFO; and decoding information bits based upon the received bits using a cycling register code.