A coherent optical modem includes an optical interface; and circuitry connected to the optical interface and configured to detect a first timing reference point in a transmit Digital Signal Processor (DSP) frame in a transmit direction from a first node to a second node, and detect a second timing reference point in a receive DSP frame in a receive direction from the second node to the first node, wherein the first timing reference point and the second timing reference point are determined based on a pattern in any DSP frame field including i) padding area, ii) a reserved area, and iii) a DSP Multi-Frame Alignment Signal (MFAS) area. The pattern can be input in select DSP frames for a time period that is greater than a time period for each DSP frame.

Particular embodiments described herein provide for an electronic device that can be configured to determine that a packet needs a timestamp, determine an initial timestamp for a reference block, communicate the reference block to a monitor engine, receive an asynchronous pulse from the monitor engine after the monitor engine received the reference block, determine a synchronization timestamp for the asynchronous pulse, and determine the timestamp for the packet based on the initial timestamp for the reference block and the synchronization timestamp for the asynchronous pulse.

A time synchronization method includes receiving, by a receive-end device, a first timestamp and a first header signal sent by a transmit-end device, where the first timestamp indicates a first moment at which a first channel medium conversion module sends the first header signal, and a second moment at which the receive-end device receives the first header signal. The method further includes sending a second header signal to the transmit-end device, where a third moment at which the receive-end device sends the second header signal. The method further includes receiving a fourth timestamp sent by the transmit-end device, where the fourth timestamp indicates a fourth moment at which the transmit-end device receives the second header signal. The method further includes synchronizing time with the transmit-end device based on the first moment, the second moment, the third moment, and the fourth moment.

A method of a reception apparatus for receiving transmission frames. The method includes receiving, by circuitry of the reception apparatus, the transmission frames transmitted on one millisecond boundaries. Each of the transmission frames includes a bootstrap, a preamble, and a payload. The method further includes determining, by the circuitry, an absolute point of time at a predetermined position in a stream of the transmission frames based on first time information included in a first one of the transmission frames.

A packet processing method includes receiving a first packet by a first receiving interface of a media conversion module of a first network device, where the first packet includes a first alignment marker (AM), sending a second packet by a first sending interface of the media conversion module, where the second packet includes the first AM, and where the second packet is the first packet processed by the media conversion module, and calculating a time interval T.sub.1 between a time at which the media conversion module receives the first packet and a time at which the media conversion module sends the second packet, where the T.sub.1 is used to compensate for a first timestamp at which the first network device receives or sends the third packet.

A frame synchronization apparatus according to an embodiment includes a reception unit, a frame memory, a time generation unit, a reception time acquisition unit, a timestamp acquisition unit, and a control unit. The reception unit is configured to receive packet data including video data and a timestamp. The frame memory is configured to store the packet data. The time generation unit is configured to generate a time based on a reference synchronization signal. The reception time acquisition unit is configured to acquire a reception time of packet data satisfying a condition based on the time. The timestamp acquisition unit is configured to acquire a timestamp from the packet data satisfying the condition. The control unit is configured to read packet data from the frame memory in accordance with a variation in a difference between the reception time and a time indicated by the timestamp.

Compact timestamps and related methods, systems and devices are described. An encoder is configured to generate compact timestamps of the disclosure by sampling states of linear feedback shift registers (LFSRs). A decoder may be configured to determine timing information responsive to the compact timestamps.

The present disclosure discloses a delay jitter compensation method and device, and a computer storage medium. The method includes: determining, by a time stamp compensation component, a current delay jitter of a data link layer according to the latest recorded data cumulant and a fixed value of data cumulant, the fixed value of data cumulant indicating a value of data cumulant without any delay jitter in the data link layer; and acquiring, by the time stamp compensation component, an initial time stamp recorded in a protocol layer, and compensating the initial time stamp according to the current delay jitter of the data link layer to obtain a compensated time stamp, the compensated time stamp being a time stamp obtained by compensating the initial time stamp.

Systems and methods for clock synchronization are disclosed in which a primary node generates special physical laver clock sync symbols from the output of a reference clock and inserts the clock sync symbols within a symbol stream to one or more secondary nodes. Upon receiving a symbol stream, a secondary node can extract the clock sync symbols from the stream to synchronize its local clock with the reference clock of the primary node. In particular, the clock sync symbols can be inserted into the symbol stream at any arbitrary symbol location, e.g., even between consecutive symbols of a symbol encoded data frame. The clock sync symbols can also replace some control symbols in the symbol stream, such as idle or comma symbols. Accordingly, the clock sync symbols can be inserted into a symbol stream at fixed intervals, irregular intervals, or at any arbitrary time for high resolution clock synchronization.

This disclosure provides systems, methods, apparatus, including computer programs encoded on computer storage media for orthogonal multiplexing of high efficiency (HE) and extremely high throughput (EHT) wireless traffic. Devices in a wireless local area network (WLAN) may operate under HE or EHT conditions. An access point (AP) may support both HE and EHT communications with WLAN devices. To enable substantially simultaneous downlink HE and EHT transmissions and substantially simultaneous uplink HE and EHT transmissions, the AP may support orthogonal frequency-division multiple access (OFDMA) of HE and EHT transmissions. For example, pre-HE and pre-EHT modulated fields, HE and EHT modulated fields, and payloads may be aligned in time for the HE and EHT transmissions. The AP may ensure orthogonality for multiplexing the HE and EHT transmissions based on the alignment. In some implementations, a trigger frame may be utilized to indicate uplink transmission alignments.