PCS Networks Research Articles

초음파 풍향 풍속계 데이터 로거 시스템의 구현

선박 통신은 1993년 ISO에서 국제 표준 규격인 RS-422통신을 이용하며, 마이크로컨트롤러들 간의 통신을 위해 설계된 시리얼 네트워크 통신 방식을 사용하였으나, 최근 NMEA2000 표준화가 진행됨에 따라 점차 빠르게 Ethernet 기반 통신 환경으로 대체 되어질 전망이다. 선박에서 사용되어지고 있는 주요 계측 장비들은 점차 범용성과 편의성을 가지는 최신 장치들을 이용해 이를 관리하게 되어짐에 따라 선박 내 다양한 곳에서 이를 활용하여 제어 및 관리 시스템들이 구현되어지고 있는 실정이다. 풍향 풍속계는 선박의 마스트 끝이나 풍력 단지 가장 높은 곳에 일반적으로 설치되어 풍향과 풍속을 계측하는 장비로써, 국제해사기구(IMO : International Maritime Organization)의 규정에 따라 필수 장비로 선박에 탑재되고 있는 장비이다. 본 논문에서는 초음파 풍향 풍속 시스템을 처리하기 위해 기존에는 별도 제어 콘솔, 데이터 로거(data-logger), 인디케이터(Indicator) 등의 제어 처리를 위한 기반 장비들이 필요하였던 시스템을 사용자 환경에 따른 PC NETWORK를 이용하여 풍향 풍속 자료 처리시스템을 구현하였다. 또한, 초음파 풍향 풍속 자료 처리 시스템을 구현하기 위한 요소 기술을 기능별 함수로 나타내었으며, NMEA 2000 표준 인증에서도 별도의 운용 콘솔 없이 풍향 풍속 자료의 처리를 위한 자료 처리 운용시스템의 기능들을 구현하고자 하였다. Until now ship communication micro serial network communication method is designed for the communication between the controller and the RS-422 communication on the international standard ISO 1993, but gradually progresses NMEA 2000 standardized fast Ethernet-based communications environments expected to be replaced. In addition, the ship's main instrumentation equipment versatility with ease gradually to control devices by monitoring and controlling are. Wind anemometer, ship mast end, where the highest wind farms typically install a separate console boxes, data loggers, indicators was required in order to manage them, to maintain them, to go through the procedures and cumbersome data update firmware were Therefore, in this paper, using the PC network, ultrasonic wind speed data processing system for implementing functional was expressed as a function of the technology elements, NMEA 2000 standard certified in separate operating console without the features of the data loggers, indicators, implementation by ultrasonic wind data processing system was implemented to minimize the maintenance cost of the operating system.

A Novel and Lightweight System to Secure Wireless Medical Sensor Networks

Wireless medical sensor networks (MSNs) are a key enabling technology in e-healthcare that allows the data of a patient's vital body parameters to be collected by the wearable or implantable biosensors. However, the security and privacy protection of the collected data is a major unsolved issue, with challenges coming from the stringent resource constraints of MSN devices, and the high demand for both security/privacy and practicality. In this paper, we propose a lightweight and secure system for MSNs. The system employs hash-chain based key updating mechanism and proxy-protected signature technique to achieve efficient secure transmission and fine-grained data access control. Furthermore, we extend the system to provide backward secrecy and privacy preservation. Our system only requires symmetric-key encryption/decryption and hash operations and is thus suitable for the low-power sensor nodes. This paper also reports the experimental results of the proposed system in a network of resource-limited motes and laptop PCs, which show its efficiency in practice. To the best of our knowledge, this is the first secure data transmission and access control system for MSNs until now.

Cloud 서버를 포함한 EPC 망에서 WLAN 오프로딩 경로 선택

There coexist various access network for mobile terminals, such as mobile phones, smart phones, and tablet PC, in mobile and wireless network. In these circumstance, the network traffic overload unexpected causes the service degradation or discontinuity. To solve this problem, we consider a off-loading route selection by a cloud server which monitors traffic volume and selects an appropriate route. With our proposed scheme, it is possible for the EPC network with untrusted WLAN access networks to operate efficiently to a trusted service level. Also, an optimal handover with satisfying service requirements could be achieved by the proposed offload scheme.

Eavesdropping the display image from conducted emission on network cable of a PC

The display image of a PC can be reconstructed by using the conducted emission on the PC's network cable. The relevant signals which be used to reconstruct the original image are coupling from the radiation of the switching of red, green, blue (RGB) signals in PC. These pertinent signals are partly contained in the frequency region higher than 30 MHz in the conducted emission. From these findings, the near-field coupling principle from PC to the network cable is analyzed firstly. And then, a multi-conductor transmission model for the RGB signals which transmit in the network cable is proposed. In addition, the maximum safe distance is estimated by using this model. In order to check the validity of the estimating distance, the eavesdropping experiment is carried out to reconstruct the original display image. The results demonstrate that the blurred display image can be retrieved at the place of 29.5 m.

Cell-related location area planning for 4G PCS networks with variable-order Markov model

Location management is a critical issue in personal communication service (PCS) networks, tracking the location of user equipment (UE) with the goal of minimizing total signaling cost. Previous work can be classified into two categories: static and dynamic. Static schemes partition networks into fixed size LAs. However, these schemes are inefficient because they do not take UEs’ mobility and the call arrival rate into account. On the other hand, focusing on individual UEs, dynamic schemes have minimized the location management cost. However, they are difficult to implement because recording the individual information of numerous UEs and planning each of their LAs consume uncontrollable cost. Because of these reasons, we propose a cell-based scheme between static and dynamic schemes. Considering people usually stay in specific zones for long periods and the movement of UEs usually presents a strong moving direction in areas, this study presents a distributed algorithm by employing variable-order Markov models to find the mobility characteristic shared by UEs to plan better LAs with lower location management cost. When the order of Markov model is set to 1, our method is equal to a pure cell-centric LAP scheme; while the order of Markov model is high, it is more like a profile-based dynamic scheme. So, the setting of the order actually is a trade-off problem between the overall location management cost and the computing complexity. We present to retrieve a balance by using the expected location management cost and the number of total states of Markov models. In simulations, the origin–destination matrix (O–D matrix) from the Taipei Rapid Transit Corporation is used for representing the association between two cells. Simulation results demonstrate that the proposed scheme achieves good performance.

Performance Analysis of Existing Location Management Scheme with its Variants in PCS Network

This paper is presenting a comparative study of existing location management scheme with its various variants in Personal Communication Services (PCS) network. The existing location management scheme is based on two tier database architecture; Home Location Register (HLR) and Visitor Location Register (VLR).In the existing location management scheme, there is a single HLR. In the HLR, profile of a Mobile Terminal (MT) is permanently stored. The VLR caches the profile of the MT from the HLR when it is providing the service to the mobile terminal. Mobile terminal, on move changes its location and comes under the Registration Area (RA) of new VLR. The MT profile should be removed from the VLR from where this MT is coming from and the HLR should have the information of current location of the MT. In the existing location management scheme this is done by the explicit deregistration scheme. In the existing call delivery procedure of PCS network, the HLR is always consulted to get the current location of the MT. This call delivery procedure supports an idea that is it necessary to inform the VLR that MT who was residing in its RA is now in the RA of another VLR? This paper has used other de-registration schemes as: Implicit deregistration, Polling de-registration, Timeout de-registration scheme and Group de-registration scheme in the variant of existing location management scheme. The single HLR architecture is prone to bottleneck and multi HLR architecture for PCS network is proposed for the efficient call delivery. Analysis done in this paper shows that we can significantly reduce the location management cost in the various variants of the existing location management schemes. This paper finally concludes that group de-registration scheme when implemented with the proposed multi HLR architecture gives better results.

Performance Evaluation of Cellular Radio System with Directed Retry

In this paper the arrival of calls (new and handoff) in personal communications services (PCS) network are modeled according a Markov Arrival Process (MAP). The purpose of our study is to improve the performance of the cellular mobile system by using directed retry scheme. The cut of priority scheme have also been applied to provide priority to handoff calls. Here we construct tractable model using fixed channel assignment scheme with priority to handoff voice calls. The proposed directed retry scheme with finite buffering for handoff voice calls is useful for improving the handoff blocking probability of handoff voice calls. The integrated traffic model has been constructed for finite population. FIFO fashion has been taken for arrival calls. The balking behavior of the calls has also been taken into consideration. The expressions for various performance indices viz. blocking probabilities for different traffic, overall blocking probability, offered carried load etc. are determined for above model. It is clear from the analytical results that by increasing overlapping area and retrying in overlapping area, a substantial improvement can be achieved.

Performance Analysis in Dynamic VLR based Location Management Scheme for the Omni Directional Mobility Movement for PCS Networks

Location management plays an important role in guaranteeing the effective operation of Personal Communication services (PCS). In this paper a dynamic VLR (visitor location register) based location management is introduced for PCS networks. In this, MSC gathers the details about mobile terminals (MT) and performs location registration. This scheme is analytically examined for Omni directional movement of MTs and also it reduces the location management cost.

Multi HLR Architecture for Improving Location Management in PCS Network

This paper proposes a multi HLR scheme for location management in PCS network instead of having a single HLR. In conventional architecture we have a single HLR that acts as centralized database to store the user profile along with the MT’s location information. This approach of single HLR suffers from two major disadvantages: bottleneck and call misrouting during the peak load. In multi HLR architecture, we store the users profile and MT’s location information zone wise or area wise. By doing so, we minimize the possibility of both bottleneck and call misrouting. In conventional architecture, we use explicit de-registration scheme for de-registration of an MT from a VLR on move. Several de-registration schemes has proposed previously in spite of explicit de-registration scheme as: implicit de-registration scheme, polling de-registration scheme, timeout de-registration scheme and group deregistration scheme. Performance analysis of all these schemes shows that group de-registration scheme is best among existing and proposed schemes. In the proposed multi HLR architecture group de-registration scheme is implemented instead of explicit de-registration scheme. Result shows that proposed architecture with group de-registration scheme is more efficient than explicit de-registration scheme.

A Modified Multi-HLR Architecture for Implicit De-registration Strategies

This study proposes a modification in the de-registration policy of Multi-HLR architecture. This architecture has made an attempt to overcome the drawbacks of Single centralized HLR architecture by introducing multiple HLRs in PCS networks in performing location managements of mobile units using explicit de-registration policy. This paper presents a modification in the de-registration policy of Multi-HLR architecture by applying the concept of implicit deregistration strategies and gives a performance analysis of this modified architecture to show how these implicit deregistration policies outperform the explicit de-registration strategy.

RETRACTED ARTICLE: New probabilistic models for managing user’s locations in PCS networks

Personal communication service (PCS) networks enable mobile terminals (MTs) to communicate regardless of their locations. However, in order to guarantee an efficient service delivery, MTs' real time locations should be perfectly managed. Location management (LM) includes two fundamental processes; registration and paging. The former is concerned with the reporting of the current locations of the MTs, while the latter is used to locate a MT. Both processes incur signaling cost across the wireless channel. The more the location updates, the less the paging signaling cost, thus there is a tradeoff in terms of signaling cost. Due to the scarcity of PCS wireless bandwidth, it is important to reduce that signaling cost. As The blanket paging in current mobile networks wastes a lot of wireless bandwidth, we focus on the subject of paging and try to reduce the paging signaling cost under a predefined delay bound. Our contribution can be summarized as: (i) establishing a family of probability based paging strategies; (ii) introducing a novel topology for PCS registration area, which is called the hot spot topology (HST); (iii) based on HST, a novel LM strategy, which is called "Flower Based Strategy" had been introduced. Experimental results had shown that that the proposed paging strategies substantially lower the signaling cost of paging compared to the blanket one with a negligible increase in paging delay.

Research of SVC Control System Based on Real-Time Operation System for Wind Farm

Wind power generation was developed rapidly in China. And many wind farms are configured Dynamic Static Var Compensators (SVCs) as reactive power compensator, which can meet the dynamic demands of the reactive power compensation for the wind farm. The paper put forward a coordination control strategy of reactive power for wind farm based on embedded real-time operation system in DSP, and by using LabVIEW to realize PC management and network communication management, and provides the research foundation for coordination and the optimal control of reactive power in large wind farm.

Distributed Fieldbus Technology for Generator Excitation System Data Storage Design

In this study is the use of the generator excitation system design parameters for distributed fieldbus technology and real-time data display module record, will transfer to the field bus data processing and real-time storage of a design. Generator current and terminal voltage and other electrical parameters by the CAN bus pass, when a failure occurs, the fault current and other electrical parameters display, and store it to MRAM or FRAM memory, and also through the external communications port to be transferred to PC and other networks. System uses magnetic resistance random access memory, ferroelectric memory extends the storage capacity, so that fault recording function can be achieved; application PIT and RTC, the timing accuracy of a millisecond, improve the recording wave function

Distributed cell-centric neighborhood-related location area planning for PCS networks

An intelligent location area planning (LAP) scheme should consider the frequent replannings of location areas (LAs) due to changes in user distribution and mobility patterns along with optimization of location management costs, including location updating and paging costs. Most schemes proposed in the literature are designed through centralized techniques, thus requiring more computing time to plan the LAs. Frequent replannings to accommodate environmental changes make the situation worse. As to the optimization of location management costs, most proposed schemes consider the inter-cell crossing rate as one of the key factors in determining the optimal partitions. In some cases, the inter-cell crossing rate may lead to an unsatisfactory outcome. Another problem is the ping-pong effect which is caused by the fixed borders between any two of LAs. In this paper, we propose a distributed cell-centric neighborhood-related LAP scheme in which each cell acts as the center of an LA and in which highly correlative neighboring cells are bundled into the LA if mobile terminals (MTs) remain within the LA long enough to reduce costs. Moreover, the ping-pong effect will be alleviated because MTs always locate at the center cell of an LA whenever a new location update is performed. Finally, the scheme can be implemented in a distributed manner so the computing time incurred by frequent replannings can be reduced. Simulation results show that our scheme indeed exhibits excellent results.

Location Management in PCS Networks Using Base Areas (BAs) and 2 Level Paging (2LP) Schemes

The main objective of PCS networks is to provide “anytime-anywhere” cellular services. Accordingly, lost calls as well as the network slow response have become the major problems that hardly degrade the network reliability. Those problems can be overcome by perfectly managing the Mobile Terminals (MTs) locations. In the existing location management (LM) scheme, Location Area (LA) is the smallest unit for registration. A MT must register itself when passing through its LA boundary to a neighboring one. Moreover, such registration takes place at the MTs’ master HLR (even though currently managed by another HLR), which increases communication costs. As a result, existing LM scheme suffers from; (1) excessive location registrations by MTs located around LA boundaries (ping-pong effect) and (2) requiring the network to poll all LA cells to locate the callee MT. In this paper, a novel LM strategy is introduced by restructuring LAs into smaller areas called Base Areas (BAs), which impacts the paging cost. The proposed LM strategy uses caching to reduce unwanted updates and 2LP to reduce paging cost. Experimental results show that the proposed scheme introduces a distinct improvement in network response and tracing process.

Mars: Accelerating MapReduce with Graphics Processors

We design and implement Mars, a MapReduce runtime system accelerated with graphics processing units (GPUs). MapReduce is a simple and flexible parallel programming paradigm originally proposed by Google, for the ease of large-scale data processing on thousands of CPUs. Compared with CPUs, GPUs have an order of magnitude higher computation power and memory bandwidth. However, GPUs are designed as special-purpose coprocessors and their programming interfaces are less familiar than those on the CPUs to MapReduce programmers. To harness GPUs' power for MapReduce, we developed Mars to run on NVIDIA GPUs, AMD GPUs as well as multicore CPUs. Furthermore, we integrated Mars into Hadoop, an open-source CPU-based MapReduce system. Mars hides the programming complexity of GPUs behind the simple and familiar MapReduce interface, and automatically manages task partitioning, data distribution, and parallelization on the processors. We have implemented six representative applications on Mars and evaluated their performance on PCs equipped with GPUs as well as multicore CPUs. The experimental results show that, the GPU-CPU coprocessing of Mars on an NVIDIA GTX280 GPU and an Intel quad-core CPU outperformed Phoenix, the state-of-the-art MapReduce on the multicore CPU with a speedup of up to 72 times and 24 times on average, depending on the applications. Additionally, integrating Mars into Hadoop enabled GPU acceleration for a network of PCs.

Performance Evaluation of Location Management Techniques in PCS Network

Location management being a major part of cellular network provides mobility to mobile subscribers. The current location information is required to route the call correctly to the recipient irrespective of its current location. The current HLR/VLR architecture for location management in standards like IS-41 & GSM suffers from call setup delay due to network congestion and also prone to failure due to its centralized nature. This paper attempts to make an evaluation of the optimized location management techniques suggesting fully distributed, hierarchical and multi HLR approach against the conventional one and also highlights the pros and cons of all the reviewed techniques.

A Novel Strategy for Managing User’s Locations in PCS Networks Based on a Novel Hot Spots Topology

As PCS networks aim to provide “anytime-anywhere” cellular services, they enable Mobile Terminals (MTs) to communicate regardless of their locations. However, in order to guarantee a successful service delivery, MTs’ real time location should be continuously managed by the network. Location management plays the central role in providing ubiquitous network communications services, which includes two fundamental processes, i.e., registration and paging. Registration is concerned with the reporting of the current locations of the MTs, while paging is used to locate the MT. Both processes incur signaling cost, and due to the scarcity of PCS wireless bandwidth and for more scalable mobile services, it is important to reduce that signaling cost. As The blanket paging in current PCS networks wastes a lot of wireless bandwidth, the author focuses on the subject of paging in attempt to reduce the paging signaling cost under delay bounds. This paper challenges the signaling cost problem and successfully establishes a family of probability based paging strategies. The author will introduce a novel topology for the network registration area, which is called the hot spot topology (HST) and based on HST, a novel location management strategy, which is called “Flower Based Strategy” (FBS) is also introduced.

An Experiment for Estimating Accurate States in Distributed Power Systems

This letter presents an experiment for estimating accurate state in distributed power systems. This letter employs a technique that combines a projected Jacobi method with a parallel dual-type method to solve the distributed state estimation with constraints problems. Via numerous tests, this letter demonstrates the efficiency of the proposed method on the IEEE 118-bus with four subsystems in a PC network.

Modelling and cost analysis of location management scheme for PCS networks

Location management is a fundamental issue of mobility management. It tracks the current location of mobile subscriber and delivers the incoming calls to them. In this paper we have proposed a modeling to estimate the location management cost, which is based on home location register cost, visitor location register cost, signalling cost, and paging cost. The proposed analytical model is helpful in describing the various parameters for overall location management cost. The numerical analysis has been carried out to explain the location management cost.