CLOCK OFFSET AND SKEW ESTIMATION

Inventors

  • Dr. James Aweya
  • Dr. Nayef Alsindi

ETISALAT BT Innovation Centre
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Much of what happens in our computing devices goes on behind-the-scenes. When our computer hooks up to the internet, or when our phone connects to a network, thousands of messages are exchanged to ensure proper operation. One critical element of such communication is synchronization. Synchronization is a process that ensures that two machines are communicating “in-sync” with each other, a way to ensure that each machine understands the sequence of messages and can detect when missing data is required. This is especially true of mobile phones. Clock synchronization between a mobile device and the radio tower is required to avoid calls being dropped. The call drops as it cannot determine the correct time stamp for data being transmitted between the phone and the tower. As mobile service providers migrate to packet networks to achieve cost efficiencies they lose the clock transfer capabilities inherent in legacy networks. Therefore clock synchronization over packet networks becomes critical for network performance.

Researchers at the Etisalat BT Innovation Center have recognized the importance of synchronization and are determined to find better ways to ensure synchronization is constant. For example, one concept is clock “skew,” where the clock on a certain device begins to drift in relation to the clock on a synchronized device. Prior methods for synchronization assumed clock skew was constant and thus only attempted to estimate the clock offset of a master and slave device. However, the researchers at EBTIC understood that skew could change over time. Thus, they proposed to ensure that the proper skew was dynamically estimated over time to ensure constant synchronization. This is done through the use of a free running clock at a slave device and a recursive estimation technique to estimate the clock offset and skew between two machine clocks, thus allowing one device to apply an offset correction to become in sync. This ensures that the estimation is dynamic and constantly accurate, increasing network reliability and reducing communication errors such as dropped calls.

Distinctive elements:

  • This invention ensures that the estimation is dynamic and constantly accurate, increasing network reliability and reducing communication errors such as dropped calls

Examples of areas of application:

  • Mobile communication and networks