Showing papers on "Precision Time Protocol published in 2018"

A Detection and Mitigation Model for PTP Delay Attack in an IEC 61850 Substation

Abstract: Smart grid applications demand the availability of a reliable and accurate time signal. Measurements and events need to be correctly aligned to enable proper actions and decisions. Precision time protocol (PTP) is the favored protocol for time distribution across smart grid domains. The correct functionality of PTP is of paramount importance and its security is of high priority. To harden its security, detection, and prevention mechanisms against attacks targeting PTP are needed. In this paper, we propose detection and mitigation mechanisms against the known PTP delay attack. We apply model checking to quantify the effect of the delay attack. Moreover, the validity of the proposed mechanism is formally proven. The suggested approach is tested on a physical system. The collected results support the usefulness of the mechanism in detecting the delay attacks targeting PTP, and preserving the system functionality.

Precise Clock Synchronization in High Performance Wireless Communication for Time Sensitive Networking

Abstract: In this paper, an enhanced precision time protocol (PTP) to enable precise clock synchronization between the nodes within an industrial wireless sensor network deployed for critical control and automation applications is proposed. As it will be shown, by incorporating clock drift factor, the accuracy of clock offset estimation of conventional PTP scheme can be significantly improved. Furthermore, in order to enhance the application of proposed clock synchronization scheme, typically in non-line-of-sight industrial communication environment, the problem of efficient symbol timing synchronization is also studied, and a simplified, yet efficient, start of the frame detector that enables robust timestamp message decoding during clock synchronization period is also proposed.

Requirements for Secure Clock Synchronization

Abstract: This paper establishes a fundamental theory of secure clock synchronization. Accurate clock synchronization is the backbone of systems managing power distribution, financial transactions, telecommunication operations, database services, etc. Some clock synchronization (time transfer) systems, such as the global navigation satellite systems, are based on one-way communication from a master to a slave clock. Others, such as the network transport protocol, and the IEEE 1588 precision time protocol (PTP), involve two-way communication between the master and slave. This paper shows that all one-way time transfer protocols are vulnerable to replay attacks that can potentially compromise timing information. A set of conditions for secure two-way clock synchronization is proposed and proved to be necessary and sufficient. It is shown that IEEE 1588 PTP, although a two-way synchronization protocol, is not compliant with these conditions, and is therefore insecure. Requirements for secure IEEE 1588 PTP are proposed, and a second example protocol is offered to illustrate the range of compliant systems.

Wireless Precision Time Protocol

Abstract: The IEEE 1588 precision time protocol (PTP) is a time synchronization protocol with sub-microsecond precision primarily designed for wired networks. In this letter, we propose wireless precision time protocol (WPTP) as an extension to PTP for multi-hop wireless networks. WPTP significantly reduces the convergence time and the number of packets required for synchronization without compromising on the synchronization accuracy.

Hardware Assisted Clock Synchronization with the IEEE 1588-2008 Precision Time Protocol

Abstract: Emerging technologies such as Fog Computing and Industrial Internet-of-Things have identified the IEEE 802.1Q amendment for Time-Sensitive Networking (TSN) as the standard for time-predictable networking. TSN is based on the IEEE 1588-2008 Precision Time Protocol (PTP) to provide a global notion of time over the local area network. Commonly, off-the-shelf systems implement the PTP in software where it has been shown to achieve microsecond accuracy. In the context of Fog Computing, it is hypothesized that future industrial systems will be equipped with FPGAs. Leveraging their inherent flexibility, the required PTP mechanisms can be implemented with minimal hardware usage and can achieve comparable synchronization results without the need for a PTP-capable transceiver. This paper investigates the practical challenges of implementing the PTP and proposes a hardware architecture that combines hardware-based timestamping with a rate adjustable clock design. The proposed architecture is integrated with the Patmos processor and evaluated on an experimental setup composed of two FPGA boards communicating through a commercial-off-the-shelf switch. The proposed implementation achieves sub-microsecond clock synchronization with a worst-case offset of 138 ns.

Implementing Proposed IEEE 1588 Integrated Security Mechanism

Abstract: A new revision of IEEE 1588 Precision Time Protocol is currently being developed, which will include revised specifications regarding security. The security mechanism consists of two verification approaches, immediate and delayed; we implemented both approaches on top of PTPd, an existing open source implementation of PTP. We support the immediate verification security approach using manual key management at startup, and we support the delayed verification security approach emulating automated key management for a set of security parameters corresponding to one manually configured time period. In our experiments, we found that added performance cost for both verification approaches was within 25 µs, and PTP synchronization quality remained intact when security was enabled.

A survey on high-precision time synchronization techniques for optical datacenter networks and a zero-overhead microsecond-accuracy solution

Abstract: A datacenter, which is a highly distributed multiprocessing system, needs to keep accurate track of time across a large number of machines. Precise time synchronization has become a critical component due to stringent requirements of several time critical applications such as real-time big data analytics, high-performance computing, and financial trading. Our study starts with a survey on the most relevant time synchronization techniques for datacenter networks. Then, we propose a zero-overhead microsecond-accuracy solution to synchronize a packet-switched optical network for datacenters. To achieve the desired time accuracy, we consider precision time protocol to synchronize the server clocks with a central controller clock. Zero-overhead is maintained by using data traffic to carry the time messages instead of a separate control channel. Through simulation, we show that microsecond level of time accuracy can be achieved. We also discuss the dependency of the accuracy on different traffic loads, traffic distributions, and packet lengths.

Encryption is Futile: Delay Attacks on High-Precision Clock Synchronization.

Abstract: Clock synchronization has become essential to modern societies since many critical infrastructures depend on a precise notion of time. This paper analyzes security aspects of high-precision clock synchronization protocols, particularly their alleged protection against delay attacks when clock synchronization traffic is encrypted using standard network security protocols such as IPsec, MACsec, or TLS. We use the Precision Time Protocol (PTP), the most widely used protocol for high-precision clock synchronization, to demonstrate that statistical traffic analysis can identify properties that support selective message delay attacks even for encrypted traffic. We furthermore identify a fundamental conflict in secure clock synchronization between the need of deterministic traffic to improve precision and the need to obfuscate traffic in order to mitigate delay attacks. A theoretical analysis of clock synchronization protocols isolates the characteristics that make these protocols vulnerable to delay attacks and argues that such attacks cannot be prevented entirely but only be mitigated. Knowledge of the underlying communication network in terms of one-way delays and knowledge on physical constraints of these networks can help to compute guaranteed maximum bounds for slave clock offsets. These bounds are essential for detecting delay attacks and minimizing their impact. In the general case, however, the precision that can be guaranteed in adversarial settings is orders of magnitude lower than required for high-precision clock synchronization in critical infrastructures, which, therefore, must not rely on a precise notion of time when using untrusted networks.

Evaluation of NTP/PTP fine-grain synchronization performance in HPC clusters

Abstract: Fine-grain time synchronization is important to address several challenges in today and future High Performance Computing (HPC) centers. Among the many, (i) co-scheduling techniques in parallel applications with sensitive bulk synchronous workloads, (ii) performance analysis tools and (iii) autotuning strategies that want to exploit State-of-the-Art (SoA) high resolution monitoring systems, are three examples where synchronization of few microseconds is required. Previous works report custom solutions to reach this performance without incurring in extra cost of dedicated hardware. On the other hand, the benefits to use robust standards which are widely supported by the community, such as Network Time Protocol (NTP) and Precision Time Protocol (PTP), are evident. With today's software and hardware improvements of these two protocols and off-the-shelf integration in SoA HPC servers no expensive extra hardware is required anymore, but an evaluation of their performance in supercomputing clusters is needed. Our results show NTP can reach on computing nodes an accuracy of 2.6 μs and a precision below 2.7 μs, with negligible overhead. These values can be bounded below microseconds, with PTP and low-cost switches (no needs of GPS antenna). Both protocols are also suitable for data time-stamping in SoA HPC monitoring infrastructures. We validate their performance with two real use-cases, and quantify scalability and CPU overhead. Finally, we report software settings and low-cost network configuration to reach these high precision synchronization results.

The implementation of IEEE 1588 clock synchronization protocol based on FPGA

Abstract: IEEE 1588 defines a precision time protocol, which is widely used in distributed test and measurement systems. It is very important to capture the timestamps of the location that can affect the synchronization accuracy seriously in the synchronization process. In this paper, we proposed a method to capture the timestamps based on specialized hardware Field Programmable Gate Array (FPGA) between the physical layer and MAC layer. We designed IEEE 1588 message detection module and frequency compensation clock to detect IEEE 1588 message and record the timestamps, respectively. This method can eliminate the delay jitter which is caused by the network protocol stack to improve the synchronization accuracy. The test experiments results show that 97.76% of the synchronization deviation is located within ±40nS.

PTP-LP: Using Linear Programming to Increase the Delay Robustness of IEEE 1588 PTP

Abstract: Clock synchronization protocols such as the precision time protocol (PTP), which are used to synchronize components of distributed systems, are fundamental to enable timed and coordinated activities, e.g., in real-time applications within the industrial Internet of things (IIoT). In theory, PTP is able to achieve a precision on the order of nanoseconds. However, its practical accuracy remains limited by packet delay variations. In this paper, we hence present a novel approach to increase the synchronization precision of PTP. Our approach (PTP-LP) relies on PTP to obtain precise hardware timestamps taken during multiple synchronization periods. These timestamps establish the constraints for a Linear Programming (LP) solver that is used to estimate the clock differences between devices. Moreover, we propose the heuristic PTP-H that achieves comparable accuracy but is less computationally complex. We evaluate PTP-LP and PTP-H in comparison with two state-of-the-art approaches under various conditions in terms of clock stabilities and packet delay distributions. PTP-LP and PTP-H are fully compatible with existing standards and show to be in particular robust to varying packet delays. Especially, PTP-LP outperforms previous approaches in presence of a stable hardware clock and unknown non-negligible network delay, which are both realistic working conditions.

Design of PTP TC/Slave Over Seamless Redundancy Network for Power Utility Automation

Abstract: IEC 61850, which drives to digitalize information in the entire system, is being increasingly adopted in the power utility industry, since the last decade. It is necessary for all devices communicating with distributed digital data to have a common understanding of time. As protection and control devices are directly related to the safety of the power system, they are strictly required to have time accuracies. This paper describes the design of a hybrid slave clock with the transparent clock (TC) functionality defined in the IEEE 1588 precision time protocol. The design objective includes not only the synchronization of the time accuracy but also the transient time, as specified in the IEC/IEEE 61850-9-3 precision time profile for power utility automation. To comply with these objectives, we adopt a hardware–software co-design approach. The timestamp of each port is implemented by hardware. Also, they are connected by hardware to calculate the bridge time on the fly, enabling the design to have a one-step TC functionality with low latency. On the other hand, the synchronizing controller is implemented by software for adapting to the varying external conditions. The controller uses the linear quadratic Gaussian (LQG) to achieve stable steady-state performance. Simultaneously, the least-squares estimator is utilized to estimate the initial conditions of the LQG controller for reducing the transition time. Experimental results show the three-sigma time inaccuracies are 15.6 ns for the TC and 149 ns for the slave with an average transition time of 13.5 s, satisfying the IEEE/IEC 61850-9-3 criteria.

A First Look at Data Center Network Condition Through The Eyes of PTPmesh

Abstract: Increased network latency and packets losses can affect substantially application performance. Due to the scale of data centers, custom network monitoring tools have been developed to measure network latency and packet loss. In our previous work, we used the Precision Time Protocol (PTP) to measure one-way delay and to quantify packet loss ratios, and we proposed PTPmesh as a cloud network monitoring tool. In this work, we provide a better understanding on how to exploit the measurement data offered by PTPmesh and present a detailed analysis of PTPmesh measurements collected in ten data centers from three cloud providers. Our findings reveal different latency, latency variance and packet loss characteristics across data centers. Through our analysis, we showcase the strengths and limitations of PTPmesh as a cloud network monitoring tool. To foster further research in this area, we make our dataset available.

Performance evaluation of IEEE 1588 protocol with modified LibPTP in OMNet

Abstract: IEEE 1588 specifically describes the Precision Time Protocol (PTP) for clock synchronization across multiple domains. The PTP implementations have a large design space because of the range of possibilities in the delay mechanism, types of clocks and topological variations. Time synchronization is considered as a challenge for real time applications such as smart grids, Internet of Things and Telecommunications etc. Multiple algorithms have been proposed to perform synchronization in which the IEEE 1588 standard defines the most reliable synchronization protocol while providing up to sub-microsecond time precision. In this paper, we have made a comparison of IEEE 1588 and IEEE 802.15.4 standards to get a sensible decision of the synchronization protocol for real time applications. Also, we have modified the existing LibPTP library to analyze the real time network traffic that can influence the synchronization process. Through simulation based studies, we have been able to analyze the performance of IEEE 1588 protocol in a constrained network.

Implementation of FPGA-Based Network Synchronization Using IEEE 1588 Precision Time Protocol (PTP)

Abstract: Synchronization is an essential prerequisite for all wired and wireless networks to operate. It is fundamental requirement for data integrity, and without it data will be affected by errors and networks will have outages. The IEEE 1588 Precision Time Protocol (PTP) enables precise synchronization of clocks via packet networks with accuracy down to the nanoseconds range. PTP-based solution can be used in various heterogeneous systems like industrial automation, RADAR, Telecom networks. FPGA-based implementation of PTP eliminates Ethernet latency and jitter issues through hardware Timestamping. It gives precise and accurate synchronization in comparison with Operating System-based Timestamping solutions. Accuracy in the range of 10–100 ns is achievable using FPGA-based platform. This paper explains basic mechanism of PTP protocol and advantages of FPGA-based platform for its implementation. It provides detail implementation of PTP on FPGA platform, design flow, testing methodology and its results.

Nanoseconds Timing System Based on IEEE 1588 FPGA Implementation

Abstract: Clock synchronization procedures are mandatory in most physical experiments where event fragments are readout by spatially dislocated sensors and must be glued together to reconstruct key parameters (e.g. energy, interaction vertex etc.) of the process under investigation. These distributed data readout topologies rely on an accurate time information available at the frontend, where raw data are acquired and tagged with a precise timestamp prior to data buffering and central data collecting. This makes the network complexity and latency, between frontend and backend electronics, negligible within upper bounds imposed by the frontend data buffer capability. The proposed research work describes an FPGA implementation of IEEE 1588 Precision Time Protocol (PTP) that exploits the CERN Timing, Trigger and Control (TTC) system as a multicast messaging physical and data link layer. The hardware implementation extends the clock synchronization to the nanoseconds range, overcoming the typical accuracy limitations inferred by computers Ethernet based Local Area Network (LAN). Establishing a reliable communication between master and timing receiver nodes is essential in a message-based synchronization system. In the backend electronics, the serial data streams synchronization with the global clock domain is guaranteed by an hardware-based finite state machine that scans the bit period using a variable delay chain and finds the optimal sampling point. The validity of the proposed timing system has been proved in point-to-point data links as well as in star topology configurations over standard CAT-5e cables. The results achieved together with weaknesses and possible improvements are hereby detailed.

Time correction method

Abstract: PROBLEM TO BE SOLVED: To improve accuracy of time correction in a system assuming a communication apparatus not in accordance with the precision time protocol (PTP).SOLUTION: A method includes calculating a measurement error on the basis of time difference between a minimum round-trip time of a packet between a master device 1 and slave devices 2a and 2b and an actual round-trip transmission time of the packet. Next, it includes obtaining a maximum amount of adjustment on the basis of a record of an amount of adjustment to internal clocks 4b and 4c of the slave devices 2a and 2b. It includes calculating estimation accuracy by multiplying the obtained maximum amount of adjustment by an elapsed time after previous adjustment. It lastly includes comparing the estimation accuracy with the measurement error, and not using the measurement value for time correction of the slave devices 2b and 2c if the measurement error is larger than the estimation accuracy.SELECTED DRAWING: Figure 1

Efficient unicast signaling in a precision time protocol enabled packet network

Abstract: A first device may provide, to a second device, a first message that includes a first request for a first type of precision time protocol (PTP) message and a second request for a second type of PTP message. The first device may receive, from the second device, a second message based on the first message. The second message may identify whether the first request and the second request are granted. The first device may provide, to the second device, a third message that instructs the second device to provide a first set of messages, associated with the first type of PTP message, and a second set of messages associated with the second type of PTP message. The first device may synchronize a first clock of the first device with a second clock of the second device based on the first set of messages and the second set of messages.

Robust Phase Offset Estimation for IEEE 1588 PTP in Electrical Grid Networks

Abstract: This paper addresses the problem of robust clock phase offset estimation for the IEEE 1588 precision time protocol in the presence of unknown asymmetric path delays in electrical grid networks. Assuming the availability of multiple master-slave communication paths, new lower bounds on the mean square estimation error for this problem were recently derived by the authors. In this paper, we present a novel phase offset estimation scheme that uses robust M-estimators for identifying the asymmetric master-slave communication paths. After discarding observations from the paths identified as asymmetric, we employ the computationally efficient L-estimators, which are linear combinations of order statistics, to estimate the phase offset from the symmetric master-slave communication paths. Simulation results show that the proposed phase offset estimation scheme exhibits performance close to the lower bounds in different network scenarios.

A reliable architecture based on Precision Time Protocol for WAMPAC synchronization

Abstract: Wide Area Monitoring Protection and Control (WAMPAC) systems play an increasingly important role in electric power system. They allow the measurement and the analysis of real time data to improve power system‘s reliability and efficiency. To work properly, every element of a WAMPAC system must be synchronized to a common reference time. Currently, the most common synchronization source is GPS, a system greatly vulnerable to cyber-attacks. To fully exploit WAMPAC systems‘ potential, cyber security issues must be taken into account. One possible solution could be the utilization of Precision Time Protocol (PTP) over Ethernet, as an alternative synchronization source.

Systems and methods for precise time synchronization with optical modules

Abstract: An optical module for use in an optical system is disclosed, the optical module implementing Precision Time Protocol (PTP) clock functionality therein. The optical module includes an electrical interface with the optical system; circuitry connected to the electrical interface and configured to implement a plurality of functions of functionality; an optical interface connected to the circuitry; and timing circuitry connected to the electrical interface and one or more of the plurality of functions, wherein the timing circuitry is configured to implement the PTP clock functionality.

Measurement Tools for Substation Equipment: Testing the Interoperability of Protocols for Time Transfer and Communication

Abstract: A test harness was designed and developed at the National Institute of Standards and Technology (NIST) to study the interoperability of the Precision Time Protocol (PTP) Power Profile and other communication standards for substation automation. Particular focus of the harness is on protocols that purport to comply to standards established by the Institute of Electronics and Electrical Engineering (IEEE) and the International Electrotechnical Commission (IEC). The test harness is intended for field evaluation of substation equipment and includes 3-phase electrical waveform generation capabilities, timing reference signal sources, measurement hardware for network clocks and software for monitoring and analyzing communication and time transfer protocols.The test harness was demonstrated at a Universal Communications Architecture International Users Group (UCAIug) Interoperability Plugfest (IOP) in 2017 where over 200 participants gathered to evaluate the interoperability between their products and tools.

Improved reference clock connection interface for prototype IEEE 1588 master clocks

Abstract: In this paper we present a fundamentally redesigned Global Navigational Satellite System (GNSS) receiver to master clock interface based on our previous design for IEEE 1588 Precision Time Protocol (PTP) master clocks. The new design is optimized for modern timing GNSS receivers; including GPS, Galileo, and GLONASS GNSS; which provide better timing accuracy and precision than previous generic navigational or even older timing GPS receivers. The new design is required because new timing GNSS receivers have lower than 10 ns error while the errors introduced by the previous interface solution is one or two magnitudes bigger than that, causing degraded system wide timing performance for new systems. Better performance is achieved by an error source analysis and a delicate component selection based on the results of the analysis, and in addition, timing oriented PCB routing. Furthermore, the new design is more compact, integrated with a CPU board, and therefore, ready to be deployed in prototype applications. The paper also provides an initial performance evaluation of the improved reference clock interface.

Adapter that converts enhanced long range navigation (eLORAN) to precision time protocol (PTP)

Abstract: A method and system are provided for converting an enhanced Long Range Navigational (eLORAN) signal to a Precision Time Protocol (PTP) signal. Network devices can be located within buildings and not have access to a GPS signal directly from a GPS satellite. Network devices may also be located in a line of sight of a GPS satellite but may lose the GPS signal. An adapter is provided that takes an eLORAN signal, when a GPS signal is lost or not available, and converts the signal into a PTP and other signals to act as timing, synchronization, and syntonization inputs into the network devices. In some cases, the network devices can have a PTP client to receive the PTP signal, one pulse per second signal, and a ten (10) megahertz frequency signal. In other cases, the network devices do not have a PTP client, but can receive a time of day message, one pulse per second signal, and the 10 megahertz frequency signal.

Design and Hardware Implementation of Improved Precision Time Protocol for High Speed Automotive Wireless Transmission System

Abstract: In this paper, a proposed hardware architecture implementation of more accuracy Precision Time Protocol (PTP) is presented. This approached design can be integrated into the wireless communication system for factory automation (FA) devices. In order to increase the closeness of the PTP harmony, we propose two approaches to improve the accurate synchronization to the nanosecond level by reducing the effects of asymmetric path delays of transmissions between master (MS) and slave (SL). The first one is the PTP protocol implementation at PHY layer to remove the random transmission jitters caused by higher layers. The second one is the full hardware implementation to remove the imbalanced timing made by the uneven hardware designs between MS and SL. Besides, a low overhead 3-frames exchange PTP approach to increase throughput of the transmission system is presented. We also implement successfully the PTP hardware design architecture and the SoPC of PHY-MAC and PTP integration system.

Synchronized High-Speed Vision Sensor Network for Expansion of Field of View.

Abstract: We propose a 500-frames-per-second high-speed vision (HSV) sensor network that acquires frames at a timing that is precisely synchronized across the network. Multiple vision sensor nodes, individually comprising a camera and a PC, are connected via Ethernet for data transmission and for clock synchronization. A network of synchronized HSV sensors provides a significantly expanded field-of-view compared with that of each individual HSV sensor. In the proposed system, the shutter of each camera is controlled based on the clock of the PC locally provided inside the node, and the shutters are globally synchronized using the Precision Time Protocol (PTP) over the network. A theoretical analysis and experiment results indicate that the shutter trigger skew among the nodes is a few tens of microseconds at most, which is significantly smaller than the frame interval of 1000-fps-class high-speed cameras. Experimental results obtained with the proposed system comprising four nodes demonstrated the ability to capture the propagation of a small displacement along a large-scale structure.

Over the air synchronization by means of a protocol in a next generation wireless network

Abstract: An integrated access and backhaul network is provided with network nodes that can establish timing synchronization with any other network nodes. In an embodiment, network nodes in a multi-hop integrated access and backhaul network have a hop order of n, wherein n represents a number of hops from a node connected to the core network via a wired connection. In an embodiment, instead of using the network node with a hop order of 0 as the timing synchronization reference for over-the-air synchronization, any network node can use any other network node as a synchronization reference. A relay node can first establish a wireless link to said arbitrary node. Said wireless link is then used to synchronize the relay or IAB node using a Precision Time Protocol (PTP) implementation.

Characterization of 1 Gbps fiber optics transceiver for high accuracy synchronization over Ethernet

Abstract: Large experiments for studying high energy physics phenomena are requiring accurate time synchronization. The wide area occupied by such kind of facilities challenges the achievable accuracy using traditional time distribution systems. At CERN, the White Rabbit (WR) project extended the Precision Time Protocol (PTP) in order to provide sub-nanosecond accuracy with standard deviation less than 50 ps. As a matter of fact, the WR systems relies also on the frequency syntonization of the L1 frontend to limit the local clock synchronization uncertainty. In particular, this work is focused only on the contribution related to the jitter of the Network Layer 1 (L1) (1 Gbps fiber optic transceiver) to the overall uncertainty. An experimental setup is proposed and the real implementation of the WR system is tested. The results show that under steady conditions the impact of the fiber optic transceiver on the overall jitter transfer is restricted to less than 0.3 ps RMS, practically negligible with respect to other uncertainty contributions of the whole system.

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

Abstract: In this paper, an extension of Precision Time Protocol (PTP) to enable energy-efficient clock synchronization between the nodes within Wireless Sensor Network (WSN) is proposed. PTP is nanosecond accuracy clock synchronization protocol in which nodes are organized in master-slave hierarchy on the basis of clock accuracy by means of Best Master Clock (BMC) algorithm. The algorithm considers clock accuracy to select best clock in the system. A novel modification of IEEE 1588 BMC algorithm for energy-constraint multi-hop WSN has been proposed to reduce clock convergence time and energy needed by considering out-degree of clocks without sacrificing synchronization accuracy. The new algorithm results in energy efficient clock synchronization that makes it most appropriate for low-power multi-hop wireless sensor networks. We present NS-3 simulation data that confirms the effectiveness of work.