A method is provided for synchronizing clocks on a plurality of audio playback devices. The method includes receiving a broadcast/multicast acknowledgement packet from a synchronization agent at a first audio playback device of the plurality of audio playback devices. A first timestamp representing a time when the acknowledgement packet was received by the first audio playback device is recorded. A broadcast/multicast timestamp packet is received from a time server at the first audio playback device. The timestamp packet includes a second timestamp representing a time when the time server received the acknowledgement packet from the synchronization agent. A local clock time on the first audio playback device is updated based on the first timestamp and the second timestamp. The method enables clock synchronization among the plurality of audio playback devices for synchronized playback of streamed audio via the plurality of audio playback devices.

Systems and methods are disclosed for direct passive monitoring of packet delay variation and time error in network packet communications. Packets traversing between slave and master clocks are monitored to provide direct results of the actual conditions without the need to rely upon inference determinations. Certain embodiments provide tap configurations to monitor packet flows, while certain other embodiments provide in-line configurations to monitor packet flows. Certain further embodiments provide multiple monitoring devices that can be used for passive monitoring purposes, such as passive monitoring to test boundary clock. These multiple monitoring devices can be configured to be within a single or different test instruments. Other variations are also described.

A network includes a first plurality of nodes operating in a first clock domain based on a first clock source, a second plurality of nodes operating in a second clock domain based on a second clock source, and synchronization circuitry accessible to both of the clock domains without requiring network traffic between the clock domains. The synchronization circuitry is configured to periodically calculate a drift rate between the time of day in the respective clock domains. Each node in one of the clock domains is configured to, when sending a message to a node in the other of the clock domains, calculate a time of day in the other of the clock domains based on an actual time of day in the one of the clock domains and the drift rate, and to include, in the message to the node in the other clock domain, the calculated time of day.

Low-cost time synchronization associated wireless Battery Management System (BMS) and a host controller are described herein. The time synchronization techniques described herein are low-cost because of the use of existing communicating lines without using adding additional dedicated lines or wires for synchronization. Moreover, the time synchronization techniques described herein may be implemented without complex circuitry.

Systems, methods and devices for adding key chain and key derivative functions (KDF) support for Network time protocol (NTP) authentication using password based key derivation functions-NTP (PBKDF-NTP) are disclosed. In one embodiment, a method includes generating time bound multiple short lived keys instead of long lived keys for NTP security which ensures that attacker will not get enough time to crack the key values. The usage of time bound multiple short lived keys instead of long lived keys for NTP security will ensure that attacker will not get enough time to crack the key values within key lifetime. Hence man-in-middle attack can be avoided in NTP.

Apparatus and methods of wireless communications include, at a receiving node, receiving timing information corresponding to a traffic class identifier. The timing information being associated with a time interval for communicating data of a traffic class corresponding to the traffic class identifier. Aspects include receiving traffic data pertaining to the traffic class, determining that the traffic data was transmitted or is received outside the time interval, and then buffering the traffic data. Additionally, aspects include forwarding the traffic data in response to a next occurrence of the time interval. A transmitting node may be configured with complimentary functions.

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.

The present disclosure provides a synchronization circuit, including M group synchronization signal generating circuits and a node synchronization signal generating circuit. For the synchronization circuit provided in the embodiments of the present disclosure, synchronization indication signals can be separately generated by a plurality of group synchronization signal generating circuits, so as to drive a node synchronization signal generating circuit to generate synchronization signals, thereby efficiently implementing synchronization control over a plurality of nodes in a multi-node environment.

Methods and systems are disclosed maintaining playback of content at a target or desired playback time. A playback device may be configured to compare a current playback time of a content asset to a target playback time of the content asset and to determine, for each comparison, whether a difference between the current playback time and the target playback time has reached a threshold. Based on determining that the difference between the current playback time and the target playback time has reached a threshold, the playback device may seek to the target playback time of the content asset. The playback device may be configured to repeatedly perform the comparing, determining and seeking operations in order to maintain the current playback time of the content within the threshold of the target playback time.

Various example embodiments for supporting scheduling of deterministic flows in time synchronized networks are presented. Various example embodiments for supporting scheduling of deterministic flows in a time synchronized network may be configured to support scheduling of deterministic flows in the time synchronized network based on assignment of transmission start times to data flows of communication devices such that the communication devices may transmit data of the data flows at the transmission start times in a manner tending to reduce or eliminate collisions in the time synchronized network.