Out-Degree Based Clock Synchronization In Wireless Networks Using Precision Time Protocol

Abstract: In the last few years there has been a growing interest in Wireless Body Area Network (WBAN) due to its latency and enhance the health care features by continuously monitoring the condition of the patient and early identification of problems. A major difficulty has been occurring to design network such as Medium Access Control (MAC) protocol that primarily part of the WBANs for functioning in a well-organized way. Therefore, it limits the sensor node energy for Quality of Service (QOS) and life cycle of the network. Accordingly, this work introduces a Versatile Synchronization Guard Band Protocol (VSGP) namely VSGP, which deals with guard band (GB) in each time slot it reduces the interference of the transmitting signal and increase the efficiency of QOS and its energy. WBAN performed with more number of sensor nodes are connected to the coordinator. VSGP protocol is compared with two existing methods called Self Adaptive Guard Band (SAGB) and Traditional Guard Band protocol. Comparisons are made with time and packet flow of each transmission and energy per packet flow.

Abstract: A common sense of time among the elements of a distributed measurement and control system allows the use of new techniques in solving problems with complex synchronization requirements or arising from the interaction of many sensors and actuators. Such a common sense of time may be accomplished using the standard IEEE 1588-2002 to synchronize real-time clocks integral to each component of the system. IEEE 1588, expands the performance capabilities of Ethernet networks so that they become relevant for measurement and control; this monograph embodies the first unified treatment of the associated technology, standards and applications. Readers will gain understanding of the technological context of IEEE 1588 and its role in a variety of application settings. To engineers this monograph provides detailed discussion of the complex features of the standard. Together with the essential material on best practice and implementation issues, these provide invaluable assistance in the design of new applications.

Abstract: The IEEE-1588 standard for a high precision time synchronization now exists since 2002. For using this standard in bridged networks a so-called boundary clock is defined, where the local clock adjustment can be modeled by a corresponding control loop. At the field level of industrial automation systems, the line topology is very important. By using Ethernet at the field level, the resulting chain of bridges leads to a cascade of control loops and may lead to instabilities and deviations of the distributed clocks, which are not acceptable. For this application a bypass clock instead of the boundary clock is proposed as an enhancement of the IEEE-1588 standard. The effectiveness of this extension to be evaluated by simulation technique.

Abstract: IEEE 1588 is a new standard to synchronize independent clocks running on separate nodes of a distributed measurement and control system. It is intended for high-accuracy implementations on compact systems such as a single subnet. This paper examines potential accuracy limitations introduced by the physical layer of the IEEE 802.11b wireless local area network. Experimental results are presented that show that these limitations do not preclude clock-synchronization accuracy of several hundred nanoseconds.

Abstract: Just like Ethernet before, IEEE 802.11 is now transcending the borders of its usage from the office environment toward real-time communication on the factory floor. However, similar to Ethernet, the availability of synchronized clocks to coordinate and control communication and distributed real-time services is not a built-in feature in WLAN. Over the years, this has led to the design and use of a wide variety of customized protocols with varying complexity and precision, both for wired and wireless networks, in accordance with the increasingly demanding requirements from real-time applications. This survey looks into the details of synchronization over IEEE 802.11 with a particular focus on the infrastructure mode which is most relevant for industrial use cases. It highlights the different parameters which affect the performance of clock synchronization over WLAN and compares the performance of existing synchronization methods to analyze their shortcomings. Finally, it identifies new trends and directions for future research as well as features for wireless clock synchronization which will be required by the applications in the near future.

Abstract: IEEE 1588 is a standard for precise clock synchronization for networked measurement and control systems in LAN environment. This paper presents the design and implementation of two IEEE 1588 prototypes for wireless LAN (WLAN). The first one is implemented using a Linux PC platform and a standard IEEE 802.11 WLAN with modifications to the network device driver. The second prototype is implemented using an embedded WLAN development board that implements the synchronization functionality using an embedded processor with programmable logic device (PLD) circuits. The measured results show that 1.1 ns average clock offset can be reached on HW based implementation, while Linux PC network driver enables 660 ns with a standard WLAN. Although WLAN is an extremely difficult environment for the synchronization, the results achieved with the prototype are fully comparable to those achieved with wired LAN implementations