Network Time Protocol

The time is very important in the life and has a special significance for hospitals, Where is specially used in operating rooms, Nurse Call System (NCS) , various medical tests and many other medical services. Those important things are mainly to use Master Clock System (MCS) in the hospitals. In this paper we provided high precision time for hospitals by used Global Positioning System (GPS) time synchronized with MCS. The time will get synchronized from satellite via GPS according to the Time Zone. GPS receivers can provide precise time, speed, and course measurements. Westerstrand GPS unit uses a miniature 12channel GPS will use in the system and its compact size and low power consumption make it ideal for this application. The system consists of Master clock control unit, GPS receiver with antenna and related accessories.

Named Data Networking (NDN) architectural features, including multicast data delivery, stateful forwarding, and in-network data caching, have shown promise for applications such as video streaming and file sharing. However, collaborative applications, requiring a multi-producer participation introduce new NDN design challenges. In this paper, we highlight these challenges in the context of the Network Time Protocol (NTP) and one of its most widely-used deployments for NTP server discovery, the NTP pool project. We discuss the design requirements for the support of NTP and NTP pool and present general directions for the design of a time synchronization protocol over NDN, coined Named Data Networking Time Protocol (NDNTP).

Named Data Networking (NDN) architectural features, including multicast data delivery, stateful forwarding, and in-network data caching, have shown promise for applications such as video streaming and file sharing. However, collaborative applications, requiring a multi-producer participation introduce new NDN design challenges. In this paper, we highlight these challenges in the context of the Network Time Protocol (NTP) and one of its most widely-used deployments for NTP server discovery, the NTP pool project. We discuss the design requirements for the support of NTP and NTP pool and present general directions for the design of a time synchronization protocol over NDN, coined Named Data Networking Time Protocol (NDNTP).

This report describes proposed changes in the security model and authentication scheme for the Network Time Protocol Version 4, which is an enhanced version of the current Versing 3. The changes are intended to replace the need to securely distribute cryptographic keys in advance, while protecting against replay and man-in-the-middle attacks. As in other schemes described in the literature, the proposed scheme is based on the use of a public-key cryptosystem to verify a server secret and from this to generate session keys for each client separately. A particularly important consequence of this design in the case of NTP is that the mechanisms for time synchronization and cryptographic signature verification must be decoupled to preserving good timekeeping quality. The schemes to do this are the main body of this report, which also includes an extensive analysis of the vulnerabilities to various kinds of hardware and software failures, as well as hostile attack.

Domain Name System (DNS) is the system for the mapping between easily memorizable host names and their IP addresses. Due to its criticality, the Internet Engineering Task Force (IETF) has defined a DNS Security Extension (DNSSEC) to provide data-origin authentication. In this paper, we point out two drawbacks of the DNSSEC standard in its handling of DNS dynamic updates: 1) the on-line storage of a zone security key, creating a single point of attack for both inside and outside attackers, and 2) the violation of the role separation principle, which in the context of DNSSEC requires the separation of the roles of zone security managers from DNS name server administrators. To address these issues, we propose an alternative secure DNS architecture based on threshold cryptography. Unlike DNSSEC, this architecture adheres to the role separation principle without presenting any single point of attack. To show the feasibility of the proposed architecture, we developed a threshold cryptography toolkit based on the Java Cryptography Architecture (JCA) and built a proof-of-concept prototype with the toolkit. Our running results of the prototype on a representative platform show that the performance of our proposed architecture ranges from one to four times of DNSSEC's performance. Thus, through small performance overhead, our proposed architecture could achieve very high level of security.

Distributed Denial-of-Service DDoS attacks have posed a challenge to Domain Name Systems DNS servers for many years. Surprisingly, no comprehensive solution has been found to protect against such attacks. In this paper, we proposed an approach by leveraging the RAID technology to protect the DNS network. Unlike DNS systems relying on one DNS server, our system incorporates multiple independent servers, each housing sets of servers holding distinct coded DNS records. This ensures that even if one server is targeted or damaged the other servers can continue functioning without any data loss or disruption in operations. Our findings demonstrate that this approach presents an answer, to the issue of DNS vulnerability towards DDoS attacks. Through the implementation of RAID technology and distribution of DNS records across servers, the suggested solution holds promising potential in creating a more reliable DNS systems capable of withstanding DDoS attacks while enhancing internet security and stability.

Accurate, reliable timestamping which is also convenient and inexpensive is needed in many important areas including real-time network applications and network measurement. Recently the TSC register, which counts CPU cycles in popular PC architectures, was proposed as the basis of a new software clock which in terms of rate performance performs as well as more expensive GPS alternatives. Smooth and precise clock rate is essential to measure time differences accurately. We show how to define a TSC based clock which is also accurate with respect to absolute time. The clock is calibrated by processing, in a novel way, timestamps contained in the usual flow of Network Time Protocol (NTP) packets between a NTP server and the existing software clock, and TSC timestamps made independently on the host side. Using real measurements over 4 months, validated with a GPS synchronized hardware timing solution, the algorithm measured absolute time with a median error of only 30 microseconds when using a nearby stratum-1 NTP server. Results for two other servers are given. We also provide new algorithms for the robust determination of clock rate. We exploit the reliability of the available hardware to design synchronization algorithms which are inherently robust to many factors including packet loss, server outages, route changes, temperature environment, and network congestion.

Ultra-high-resolution tiled display walls are typically driven by a cluster of computers. Each computer may drive one or more displays. Synchronization between the computers is necessary to ensure that animated imagery displayed on the wall appears seamless. Most tiled display middleware systems are designed around the assumption that only a single application instance is running in the tiled display at a time, therefore synchronization can be achieved with a simple solution such as a networked barrier. When a tiled display has to support multiple applications at the same time, the simple networked barrier approach does not scale. In this paper we propose and experimentally validate two synchronization algorithms to achieve low-latency inter-tile synchronization for multiple applications with independently varying frame-rates. The Two-Phase algorithm is more generally applicable to various high-resolution tiled display systems. The One-Phase algorithm provides superior results but requires the support for NTP, and is more CPU-intensive.

View image, dig sector, and "digability" data products generated onboard the lander. 2. Given a set of raw images from a stereo pair of mast cameras, generate image, dig sector, and dig hazard products identical to what would be generated onboard the lander and view them. 3. Given a set of image products downlinked from the lander, generate dig sector and dig hazard products identical to what would be generated onboard the lander and view them. The ground tool can be used to view the 3D reconstruction of the terrain. The mouse buttons can be used to rotate the 3D model of the terrain and zoom in and out. Drop-down menus enable the user to display the dig sectors, one of the eight goodness image layers, and the merged goodness map layer. When viewing a goodness map layer, the dig sectors within the 3D reconstruction are color-coded. Green sectors are safe for digging. The colors between green and red correspond to the increasing level of risk.

This paper presents and evaluates a high-precision, one-way, master-to-slave time synchronization protocol to minimize the clock time skew in low-power wearable sensor networks. The protocol is implemented in the MAC layer, and is based on directly eliminating deterministic delays during transmission from source to destination node, at hardware level. The proposed protocol keeps the one-hop average synchronization error close to the signal propagation delay and the one-hop peak-to-peak jitter equal to the period of each node's system clock period. Both values grow linearly as the hop count increases. The protocol can achieve synchronization in the range of a few nanoseconds, enough to satisfy the requirements of many applications for wearable networks, with one-way messages. Both theoretical analysis and experimental results, in wired wearable networks, show that the proposed protocol has a better performance than PTP, a standard timing protocol for both single and multihop situations. The proposed approach is simpler, requires no calculations, and exchanges fewer messages. Experimental results obtained with an implementation of the protocol in 0.35 µm CMOS technology show that this approach keeps the one-hop average clock skew around 4.6 ns and peak-to-peak skew around 50 ns for a system clock frequency of 20 MHz.

The telecommunication networks of telecontrol systems in electric utilities have undergone an innovation process. This has removed many of their technical restrictions and made it possible to consider carrying out telecontrol tasks with general standard protocols instead of the specific ones that are used currently. These are defined in the standards 60870-5, 60870-6, and 61850 from the International Electrotechnical Commission, among others. This paper is about the implementation, using the services of general standard protocols, of the telecontrol application functions defined by the standard IEC 60870-5-104. The general protocols used to carry out telecontrol tasks are those used in the Internet: the telecommunication network-management protocol SNMPv3 (simple network management protocol version 3), the clock synchronization protocol network time protocol and Secure SHell. With this new implementation, we have achieved, among others, two important aims: 1) to improve performance and, above all, 2) to solve the serious security problems present in the telecontrol protocols currently being used. These problems were presented by IEEE in an article published in the website of the IEEE Standards Association. In this paper, the use of general standard protocols to perform the telecontrol of electrical networks is justified. The development of this paper-its achievements and conclusions and the tools used-is detailed.

We identify two attacks on the Network Time Protocol (NTP)'s cryptographically-authenticated broadcast mode. First, we present a replay attack that allows an on-path attacker to indefinitely stick a broadcast client to a specific time. Second, we present a denial-of-service (DoS) attack that allows an off-path attacker to prevent a broadcast client from ever updating its system clock; to do this, the attacker sends the client a single malformed broadcast packet per query interval. Our DoS attack also applies to all other NTP modes that are 'ephemeral' or 'preemptable' (including manycast, pool, etc). We then use network measurements to give evidence that NTP's broadcast and other ephemeral/preemptable modes are being used in the wild. We conclude by discussing why NTP's current implementation of symmetric-key cryptographic authentication does not provide security in broadcast mode, and make some recommendations to improve the current state of affairs.

We explore the risk that network attackers can exploit unauthenticated Network Time Protocol (NTP) traffic to alter the time on client systems. We first discuss how an onpath attacker, that hijacks traffic to an NTP server, can quickly shift time on the server's clients. Then, we present an extremely low-rate (single packet) denial-of-service attack that an off-path attacker, located anywhere on the network, can use to disable NTP clock synchronization on a client. Next, we show how an off-path attacker can exploit IPv4 packet fragmentation to dramatically shift time on a client. We discuss the implications of these attacks on other core Internet protocols, quantify their attack surface using Internet measurements, and suggest a few simple countermeasures that can improve the security of NTP. Permission to freely reproduce all or part of this paper for noncommercial purposes is granted provided that copies bear this notice and the full citation on the first page. Reproduction for commercial purposes is strictly prohibited without the prior written consent of the Internet Society, the first-named author (for reproduction of an entire paper only), and the author's employer if the paper was prepared within the scope of employment.

For decades, the Network Time Protocol (NTP) has been used to synchronize computer clocks over untrusted network paths. This work takes a new look at the security of NTP's datagram protocol. We argue that NTP's datagram protocol in RFC5905 is both underspecified and flawed. The NTP specifications do not sufficiently respect (1) the conflicting security requirements of different NTP modes, and (2) the mechanism NTP uses to prevent off-path attacks. A further problem is that (3) NTP's control-query interface reveals sensitive information that can be exploited in off-path attacks. We exploit these problems in several attacks that remote attackers can use to maliciously alter a target's time. We use network scans to find millions of IPs that are vulnerable to our attacks. Finally, we move beyond identifying attacks by developing a cryptographic model and using it to prove the security of a new backwards-compatible client/server protocol for NTP. implementations of NTP). The chronyd/openntpd protocol is secure, but unlike our protocol, does not preserve the semantics of packet timestamps. Sender Receiver Off-path attacker Sender Receiver On-path attacker Sender Receiver Man in the middle 1 This follows because time-synchronization protocols use information about the delay on the network path in order to accurately synchronize clocks (Section 2). A client cannot distinguish the delay on the forward path (from client to server) from the delay on the reverse path (from server to client). As such, the client simply takes the total round trip time δ (forward path + reverse path), and assumes that delays on each path are symmetric. The MiTM can exploit this by making delays asymmetric (e.g., causing the delay on the forward path to be much longer than delay on the reverse path), thus biasing time synchronization.

RFC 5905 [RFC5905] states that Network Time Protocol (NTP) packets should be authenticated by appending a 128-bit key to the NTP data, and hashing the result with MD5 to obtain a 128-bit tag. This document deprecates MD5-based authentication, which is considered to be too weak, and recommends the use of AES-CMAC [RFC4493] as a replacement.https://datatracker.ietf.org/doc/draft-ietf-ntp-mac/First author draf

We consider the problem of sending messages into the future, commonly known as timed release cryptography. Existing schemes for this task either solve the relative time problem with uncontrollable, coarse-grained release time (time-lock puzzle approach) or do not provide anonymity to senders and/or receivers and are not scalable (serverbased approach). Using a bilinear pairing on any Gap Diffie-Hellman group, we solve this problem by giving scalable, server-passive and user-anonymous timed release public-key encryption schemes allowing precise absolute release time specifications. Unlike the existing server-based schemes, the trusted time server in our scheme is completely passive-no interaction between it and the sender or receiver is needed; it is even not aware of the existence of a user, thus assuring the privacy of a message and the anonymity of both its sender and receiver. Besides, our scheme also has a number of desirable properties including a single form of update for all users, self-authenticated time-bound key updates, and key insulation, making it a scalable and appealing solution. It could also be easily generalized to a more general policy lock mechanism.

This study is the further research into previous study and there are changes made. The first change is to include the measuring capacity that is Equation (1) and the second change is the amendment to equation (3) relates to correction compensation. This study proposes statistical base criteria for the selection of the most appropriate measuring instrument. Three formulae are proposed completely different from the traditional methods and MSA. Procedures to implement and follow up actions too, are provided so that readers could follow the steps easily to avoid mistakes. Equation (1) is novel because it deals with the problem of measuring instrument capacity which has not been mentioned and taken for granted in the past by traditional methods and MSA. There is no doubt that these procedures are more complicated than the traditional methods; however they are convincing due to the use of statistical information and measurement uncertainty couple with the current concept of metrological traceability.

Unlike traditional data traffic, real time multimedia traffic requires synchronization. Temporal relationships among media must be maintained. Yet delay jitter and the absence of a global clock may disrupt these temporal relationships. This paper introduces new group synchronization protocols for real time, multimedia applications, including teleconference, teleorchstration and multimedia on demand services. The proposed protacols achieve synchronization for all configurations (one-to-one, oneto-many, many-to-one, and many-to-many), and does so without prior knowledge of the end-to-end delay distribution, or the distribution of the clock drift. The only Ca-primi knowIedge the protocols require is an upper bound on the end-to-end delay. The paper concludes with simulation experiments showing that the protocols work effectively in both LAN and WAN environments. Index Terms-High speed networks, multimedia services, synchronization, asynchrony, delay jitter, local clock drift, E t i d collection time, initial playback times, performance evaluation.

We present RT-P2P, a real-time peer-to-peer (P2P) system that allows application-level end-to-end timing requirements to be satisfied in P2P systems. P2P systems are fundamentally characterized by: a large number of geographically distributed nodes that require little infrastructural support from the underlying network; an unbounded number of nodes (a permanently evolving set of nodes); and consequently no process/node with global knowledge of the system structure. Interesting features of such networks include the fact that they allow a rich set of nodes to act as relay points for other nodes, and a rich set of overlay paths (selected by peers) to be constructed. These features have traditionally made overlay routing-where end hosts have the flexibility of routing traffic to their destinations through the desired choice of intermediate overlay nodes (unlike in IP routing)-a very attractive approach for end-to-end performance optimizations in P2P networks. Key aspects of our RT-P2P infrastructure include a real-time P2P protocol, real-time communication algorithm, and analytical performance models. We analytically establish the timing properties of RT-P2P. Our simulation studies validate our analytical results.

This document arguments and requests re-allocation of an UDP port number from the System Ports range for a Reflector in Two-Way Active Measurement Protocol (TWAMP). This document, if accepted, will be an update to the TWAMP Test protocol specified in RFC 5357.

This document describes an OPTIONAL feature for active performance measurement protocols allowing use of the Precision Time Protocol time stamp format defined in IEEE-1588v2-2008, as an alternative to the Network Time Protocol that is currently used. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts.

The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Precise time synchronization is expected to play a key role in emerging distributed and real-time applications such as the smart grid and Internet of Things (IoT) based applications. The Precision Time Protocol (PTP) is currently viewed as one of the main synchronization solutions over a packet-switched network, which supports microsecond synchronization accuracy. In this paper, we present a PTP simulation model for OMNeT++ INET, which allows to investigate the synchronization accuracy under different network configurations and conditions. To show some illustrative simulation results using the developed module, we investigate on the network load fluctuations and their impacts on the PTP performance by considering a network with classbased quality-of-service (QoS) support. The simulation results show that the network load significantly affects the network delay symmetry, and investigate a new technique called class probing to improve the PTP accuracy and mitigate the load fluctuation effects.

The Proximity-1 Space Link Interleaved Time Synchronization (PITS) protocol provides time distribution and synchronization services for space systems. A software prototype implementation of the PITS algorithm has been developed that also provides the test harness to evaluate the key functionalities of PITS with simulated data source and sink. PITS integrates time synchronization functionality into the link layer of the CCSDS Proximity-1 Space Link Protocol. The software prototype implements the network packet format, data structures, and transmit-and receive-timestamp function for a time server and a client. The software also simulates the transmitand receive-time stamp exchanges via UDP (User Datagram Protocol) socket between a time server and a time client, and produces relative time offsets and delay estimates.

___ Time synchronization is a critical piece of infrastructure for any distributed system. Wireless sensor networks have emerged as an important and promising research area in the recent years. Time synchronization is important for many sensor network applications that require very precise mapping of gathered sensor data with the time of the events, for example, in tracking and vehicular surveillance. It also plays an important role in energy conservation in MAC layer protocols. The paper studies different existing methods, protocols, significant time parameters (clock drift, clock speed, synchronization errors, and topologies) to achieve accurate synchronization in a sensor network. The studied Synchronization protocols include conventional time sync protocols (RBS, Timing-sync Protocol for Sensor Networks-TPSN, FTSP), and other application specific approaches such as all node-based approach, a diffusion-based method and group sync approaches aiming at providing network-wide time. The goal for writing this paper is to study most common existing time synchronization approaches and stress the need of a new class of secure-time synchronization protocol that is scalable, topology independent, fast convergent, energy efficient, less latent and less application dependent in a heterogeneous hostile environment. Our survey provides a valuable framework by which protocol designers can compare new and existing synchronization protocols from various metric discussed in the paper. So, we are hopeful that this paper will serve a complete one-stop investigation to study the characteristics of existing time synchronization protocols and its implementation mechanism in a Sensor network environment.

Synchronization is required in all types of wireless sensor networks in any situation that requires time-based collaboration of one or more of the nodes of the network. A major example of this need for synchronization is a position location network in which the positions of objects are calculated based on time of flight measurements made at several nodes. The accuracy of synchronization becomes more important as the requirement for measurement accuracy increases. This paper reviews literature that is currently available on methods of achieving and improving the accuracy of synchronization in distributed sensor networks.

___ Time synchronization is a critical piece of infrastructure for any distributed system. Wireless sensor networks have emerged as an important and promising research area in the recent years. Time synchronization is important for many sensor network applications that require very precise mapping of gathered sensor data with the time of the events, for example, in tracking and vehicular surveillance. It also plays an important role in energy conservation in MAC layer protocols. The paper studies different existing methods, protocols, significant time parameters (clock drift, clock speed, synchronization errors, and topologies) to achieve accurate synchronization in a sensor network. The studied Synchronization protocols include conventional time sync protocols (RBS, Timing-sync Protocol for Sensor Networks-TPSN, FTSP), and other application specific approaches such as all node-based approach, a diffusion-based method and group sync approaches aiming at providing network-wide time. The goal for writing this paper is to study most common existing time synchronization approaches and stress the need of a new class of secure-time synchronization protocol that is scalable, topology independent, fast convergent, energy efficient, less latent and less application dependent in a heterogeneous hostile environment. Our survey provides a valuable framework by which protocol designers can compare new and existing synchronization protocols from various metric discussed in the paper. So, we are hopeful that this paper will serve a complete one-stop investigation to study the characteristics of existing time synchronization protocols and its implementation mechanism in a Sensor network environment.

___ Time synchronization is a critical piece of infrastructure for any distributed system. Wireless sensor networks have emerged as an important and promising research area in the recent years. Time synchronization is important for many sensor network applications that require very precise mapping of gathered sensor data with the time of the events, for example, in tracking and vehicular surveillance. It also plays an important role in energy conservation in MAC layer protocols. The paper studies different existing methods, protocols, significant time parameters (clock drift, clock speed, synchronization errors, and topologies) to achieve accurate synchronization in a sensor network. The studied Synchronization protocols include conventional time sync protocols (RBS, Timing-sync Protocol for Sensor Networks-TPSN, FTSP), and other application specific approaches such as all node-based approach, a diffusion-based method and group sync approaches aiming at providing network-wide time. The goal for writing this paper is to study most common existing time synchronization approaches and stress the need of a new class of secure-time synchronization protocol that is scalable, topology independent, fast convergent, energy efficient, less latent and less application dependent in a heterogeneous hostile environment. Our survey provides a valuable framework by which protocol designers can compare new and existing synchronization protocols from various metric discussed in the paper. So, we are hopeful that this paper will serve a complete one-stop investigation to study the characteristics of existing time synchronization protocols and its implementation mechanism in a Sensor network environment.

Having in mind multimedia systems applications, we propose a novel model-based approach to estimate the clock-offset between two nodes on the Internet. Different than current clock-offset schemes in the literature, which are iterative in nature, our scheme is aimed at getting a good non-iterative clock-offset estimation in real time (in the order of milliseconds). In our clock-offset estimation approach, the One-Way Delay (OWD) measurements are modeled with a shifted gamma distribution representing the current state of the probing link. By using the QQ-probability plot technique and linear regression model, we estimate the (shift parameter or) minimum value of the gamma distribution with probability zero. This estimated value represents the clock offset plus network propagation and transmission delay (queuing delay has already been eliminated) for the corresponding receiving path. End nodes exchange their corresponding minimum estimates and get an improved final clock offset estimate considering the network path asymmetries. Based on real experiments, we show that our scheme provides an extremely fast clock-offset estimation with lower RMSE and superior stability than NTP and current NTP-like state of the art methodologies in the literature Jeske and Sampath (2003), Choi and Yoo (2005), Adhikari et al. (2003), Tsuru et al. (2002). Moreover, our proposed scheme is non-intrusive (no kernel programming needed), easy to implement, and targeted as part of more complex real-time multimedia distribution protocols requiring a fast and reliable OWD estimates.

Precise time synchronization has become a critical component of modern power systems. There are several available methods for synchronizing the intelligent electronic devices (IEDs) in a power system. In recent years, there has been great interest in providing time to the IEDs using the same infrastructure through which the data are communicated. Precision Time Protocol (PTP) is a promising technology for achieving submicrosecond synchronization accuracy between IEDs over Ethernet. This paper presents the protocol fundamentals and discusses considerations for designing power system networks to achieve submicrosecond accuracies. Specific provisions made in the profile for power system applications to support IEC 61850 substation automation systems are also discussed.

With virtual assistants, both changes and serious conveniences are provided in human life. For this reason, the use of virtual assistants is increasing. The virtual assistant software has started to be produced as separate devices as well as working on phones, tablets, and computer systems. Google Home is one of these devices. Google Home can work integrated with smart home systems and various Internet of Things devices. The security of these systems is an important issue. As a result of attackers taking over these systems, very serious problems may occur. It is very important to take the necessary actions to detect these problems and to take the necessary measures to prevent possible attacks. The purpose of this study is to test whether an attack that attackers can make to these systems via network time protocol will be successful or not. Accordingly, it has been tried to attack the wireless connection established between Google Home and an Internet of Things device over the networ...

This paper describes a series of experiments involving over 100,000 hosts of the Internet system and located in the U.S., Europe and the Pacific. The experiments are designed to evaluate the availability, accuracy and reliability of international standard time distribution using the Internet and the Network Time Protocol (NTP), which has been designated an Internet Standard protocol. NTP is designed specifically for use in a large, diverse internet system operating at speeds from mundane to lightwave. In NTP a distributed subnet of time servers operating in a self-organizing, hierarchical, master-slave configuration exchange precision timestamps in order to synchronize host clocks to each other and national time standards via wire or radio.The experiments are designed to locate Internet hosts and gateways that provide time by one of three time distribution protocols and evaluate the accuracy of their indications. For those hosts that support NTP, the experiments determine the distri...

In Heterogeneous Network (HetNet) for LTE/LTE-A system femtocells (HeNodeBs) are designed and implemented to extend coverage and capacity. The arbitrary usage of HeNodeBs supported for indoor coverage is linked through a third-party internet backhaul to the HeNodeB managing server, and this is a segment of the operators end. To sustain HeNodeBs to the control function IEEE1588, master slave strategy is put in effect. Nevertheless, caused by the absence of internet or unfortunate connectivity for a prolonged period HeNodeBs undergoes synchronization difficulties that leads to frequency mismatch With this paper, a kind of self-organizing method is suggested for time synchronization in Heterogeneous Network, and that is standardized using IEEE1588 master slave method along with Precision Timing Protocol (PTP). The proposed approach is two way message transmission system, adopting the Least-squares Linear Regression Algorithm (LSRA) to reduce offsets as well as frequency misalignments (drift).

The telecommunication networks of telecontrol systems in electric utilities have undergone an innovation process. This has removed many of their technical restrictions and made it possible to consider carrying out telecontrol tasks with general standard protocols instead of the specific ones that are used currently. These are defined in the standards 60870-5, 60870-6, and 61850 from the International Electrotechnical Commission, among others. This paper is about the implementation, using the services of general standard protocols, of the telecontrol application functions defined by the standard IEC 60870-5-104. The general protocols used to carry out telecontrol tasks are those used in the Internet: the telecommunication network-management protocol SNMPv3 (simple network management protocol version 3), the clock synchronization protocol network time protocol and Secure SHell. With this new implementation, we have achieved, among others, two important aims: 1) to improve performance and, above all, 2) to solve the serious security problems present in the telecontrol protocols currently being used. These problems were presented by IEEE in an article published in the website of the IEEE Standards Association. In this paper, the use of general standard protocols to perform the telecontrol of electrical networks is justified. The development of this paper-its achievements and conclusions and the tools used-is detailed.

Homogenization of the higher education area in accordance to the Bologna process is one of the priority task in both countries. Faculties especially responsible for education of surveyors in both countries have started to develop new curricula, rules and new standards aimed to unify the education and support the efforts to obtain a new global market of surveyors capable to satisfy everyday's needs and successfully compete in the EU labor market. The teachers of two Universities, Kyiv National university of Construction and Architecture (KNUCA), Faculty of GIS & Land Management-Department of surveying and cadastre (Ukraine) and University of Belgrade-Faculty of Civil Engineering-Department of geodesy and geoinformatics (Serbia) found the very interesting to analyze actual situation in both countries. The analysis and comparing of the surveyor's education programs investigate and appreciate the possibilities for mutual recognition of studies and facilitate student's and teacher's mobility. This research is very important as an idea how to define the minimum of common program content that is enough for diploma recognition or mobility requirements for the new student's generation.

Precise time synchronization has become a critical component of modern power systems. There are several available methods for synchronizing the intelligent electronic devices (IEDs) in a power system. In recent years, there has been great interest in providing time to the IEDs using the same infrastructure through which the data are communicated. Precision Time Protocol (PTP) is a promising technology for achieving submicrosecond synchronization accuracy between IEDs over Ethernet. This paper presents the protocol fundamentals and discusses considerations for designing power system networks to achieve submicrosecond accuracies. Specific provisions made in the profile for power system applications to support IEC 61850 substation automation systems are also discussed.

This paper presents the complete design and implementation of a low-cost, low-footprint, network time protocol server core for field programmable gate arrays. The core uses a carefully designed modular architecture, which is fully implemented in hardware using digital circuits and systems. Most remarkable novelties introduced are a hardware-optimized timekeeping algorithm implementation, and a full-hardware protocol stack and automatic network configuration. As a result, the core is able to achieve similar accuracy and performance to typical high-performance network time protocol server equipment. The core uses a standard global positioning system receiver as time reference, has a small footprint and can easily fit in a low-range field-programmable chip, greatly scaling down from previous system-on-chip time synchronization systems. Accuracy and performance results show that the core can serve hundreds of thousands of network time clients with negligible accuracy degradation, in con...

We present a detailed re-examination of the problem of inexpensive yet accurate clock synchronization for networked devices. Based on an empirically validated, parsimonious abstraction of the CPU oscillator as a timing source, accessible via the TSC register in popular PC architectures, we build on the key observation that the measurement of time differences, and absolute time, requires separate clocks, both at a conceptual level and practically, with distinct algorithmic, robustness, and accuracy characteristics. Combined with round-trip time based filtering of network delays between the host and the remote time server, we define robust algorithms for the synchronization of the absolute and difference TSCclocks over a network. We demonstrate the effectiveness of the principles, and algorithms using months of real data collected using multiple servers. We give detailed performance results for a full implementation running live and unsupervised under numerous scenarios, which show very high reliability, and accuracy approaching fundamental limits due to host system noise. Our synchronization algorithms are inherently robust to many factors including packet loss, server outages, route changes, and network congestion.

The femtocell network allows connecting to cellular network through broadband connection. In femtocell, time with network synchronization becomes a critical issue at present. Synchronization is a process which is required in the femtocell network due to the shortcomings of centralized coordination between a number of femtocell Base Station (fBS) and clock synchronization server. Time synchronization procedure allows exchanging message that contains timestamp and delay measurement. There are several time synchronization protocols and algorithms based on precision which are Network Time Protocol (NTP), Simple Network Time Protocol (SNTP), IEEE 1588 Timing Protocol, enhancement of IEEE 1588 timing and receiverreceiver synchronization scheme. In this study, we investigated some of the time synchronization protocols and schemes for femtocell network. In addition, we proposed intra-cluster synchronization scheme to minimize the clock offset and skew for better synchronization accuracy. The proposed scheme is able to perform precise synchronization for clock offset and clock skew than the existing receiver-receiver synchronization scheme.