LAN Access Research Articles

The Medical Infusion Alarm System Based on the Smart Phone Platform

Using the Windows Phone 7.5 smart phones as platform and the Silverlight technology designed and developed a set of complete infusion alarm system. With its own wireless Wi-Fi capabilities, through the hospital's wireless LAN access patient information, the smart phone can carry, solved the problem of the past that medical staff must stay in front of the computer, it can understand infusion information at any time, in time to tackle the problem of infusion and get the alarm information, and improves the work efficiency of medical personnel.

Road Side Unit Deployment: A Density-Based Approach

Currently, the number of vehicles increases every year, raising the probability of having accidents. When an accident occurs, wireless technologies enable vehicles to share warning messages with other vehicles by using vehicle to vehicle (V2V) communications, and with the emergency services by using vehicle to infrastructure (V2I) communications. Regarding vehicle to infrastructure communications, Road Side Units (RSUs) act similarly to wireless LAN access points, and can provide communications with the infrastructure. Since RSUs are usually very expensive to install, authorities limit their number, especially in suburbs and areas of sparse population, making RSUs a precious resource in vehicular environments. In this paper, we propose a Density-based Road Side Unit deployment policy (D-RSU), specially designed to obtain an efficient system with the lowest possible cost to alert emergency services in case of an accident. Our approach is based on deploying RSUs using an inverse proportion to the expected density of vehicles. The obtained results show how D-RSU is able to reduce the required number of RSUs, as well as the accident notification time.

Proactive QoS Enhancement Technique for Efficient VoIP Performance over Wireless LAN and Cognitive Radio Network

VoIP over Wireless LANs is greatly affected bypath-loss, RF interference and other sources of signalattenuation in addition to network congestion. The primaryfactors involved in effective real-time communication,namely delay and loss, must be within certain controlledlimits in such a scenario. Wireless LAN Access Points must,therefore, act in tune with the codecs to ensure high qualityof the ongoing VoIP sessions. Further deployment of VoIPin opportunistic communication medium like cognitiveradio network requires thorough analysis of the factorsinvolved in design and implementation of such networksalong with modifications in VoIP parameters. In this paper,the various codec parameters are analyzed with respect towireless LAN access points. Thereafter, an optimizationalgorithm is developed based on proactive strategy to keeploss and latency within tolerable limits. The proposedalgorithm is hence implemented in the SIP enabled test-bedto provide optimum Voice over IP (VoIP) performance. Theproactive strategy is further applied to study VoIPperformance over cognitive radio networks. A simulationmodel is developed for VoIP transmission in cognitive radionetworks with two scenarios where the primary and thesecondary user involve in VoIP transmission respectively.For each scenario, extensive analysis of both VoIP and CRNparameters is performed and an algorithm is proposedbased on codecs and active queues to ensure highthroughput of VoIP traffic with enhanced QoS. Resultsverify significant performance improvement in VoIP callquality under both wireless LAN and cognitive radionetwork environment. Simulation and measured resultshave also been included.

A Research on HCCA Mechanism of Wireless LAN Access

Analyzed the q uality of s ervice (Q os ) scheduling mechanism of IEEE802. 11e, discussed the simple scheduling algorithm (Simple Scheduler) and its deficiencies exist in supporting variable bit-rate service (VBR). And then proposed a improved algorithm which adapts to the real time VBR service. The algorithm can dynamically adjust the service interval and the TXOP of per flow. Finally, implement the algorithm on NS2. Compared with the HCCA, simulation results show that our mechanism

The Application of the TCP/IP on the Robot System

This paper puts forward a control model that is made up of the series robot, the parallel moving platform and the polishing tool system and so on. In order to realize the communication between the two robots in the robot system, a wireless LAN access point for establishing wireless LAN of two robots communication is first provided. In the end, the mutual communication can be accomplished by two robots and the robot position and status information can be transported with programming of the win socket. The satisfied polishing effect on the curved surfaces can be obtained and the demand of the polishing can be achieved.

A Synchronized Multipoint Vision-Based System for Displacement Measurement of Civil Infrastructures

This study presents an advanced multipoint vision-based system for dynamic displacement measurement of civil infrastructures. The proposed system consists of commercial camcorders, frame grabbers, low-cost PCs, and a wireless LAN access point. The images of target panels attached to a structure are captured by camcorders and streamed into the PC via frame grabbers. Then the displacements of targets are calculated using image processing techniques with premeasured calibration parameters. This system can simultaneously support two camcorders at the subsystem level for dynamic real-time displacement measurement. The data of each subsystem including system time are wirelessly transferred from the subsystem PCs to master PC and vice versa. Furthermore, synchronization process is implemented to ensure the time synchronization between the master PC and subsystem PCs. Several shaking table tests were conducted to verify the effectiveness of the proposed system, and the results showed very good agreement with those from a conventional sensor with an error of less than 2%.

Erratum to: Wireless LAN Access Point Placement Based on User Mobility

The first author is Mohd Fikri Azli bin Abdullah. The first author’s affiliations are Faculty of Information Science and Technology, Multimedia University, Malacca, Malaysia and School of Electronics and Computer Engineering, Chonnam National University, Gwangju, South Korea respectively. The second author’s full name is Muhammad Taufiq Nuruzzaman. The second author’s affiliation is Department of Informatics Engineering, State Islamic University Sunan Kalijaga, Yogyakarta, Indonesia. Corresponding author is the first author. It is correct in this erratum.

Wireless LAN Access Point Placement Based on User Mobility

In a wide area campus, a university provides Wireless Local Area Network (WLAN) for users to connect to the Internet. Most users take advantage of this WLAN benefit by using their laptops. However, the number of smart phone users is growing fast. Since a smart phone is able to get an Internet connection using WLAN, users can use their smart phones without having to pay for a cellular operator. Users tend to use their smart phones more, due to their higher mobility compared to a laptop. This capability enables new services in the market, such as Fixed-Mobile Convergence (FMC), which integrates a fixed network (traditional telephony, WLAN) and a mobile network (cellular) to provide seamless voice communications anytime, anywhere. These new applications require a WLAN connection availability nearly everywhere. However, due to limited budgets, a university can only install APs in places with a high connection demand. We propose a novel WLAN AP placement technique that takes user mobility into consideration. This new approach is more complete than previous approaches, which mainly focus on coverage area and throughput data. Our technique has been implemented in our university. The results show the suitability of the WLAN access point locations in our university campus based on user mobility and activities.

Power Saving Control Method for Battery-Powered Portable Wireless LAN Access Points in an Overlapping BSS Environment

This paper proposes a power saving control method for battery-powered portable wireless LAN (WLAN) access points (APs) in an overlapping basic service set (OBSS) environment. The IEEE802.11 standard does not support power saving control for APs. Some conventional power saving control methods for APs have been proposed that use the network allocation vector (NAV) to inhibit transmission at stations (STAs) while the AP is sleeping. However, since with these approaches the actual beacon interval in the OBSS environment may be extended due to the NAV as compared to the beacon interval which is set at the AP, the power consumption and delay may be increased as compared to a single BSS unaffected by interference from neighboring APs. To overcome this problem, this paper introduces a new action frame named power saving access point (PSAP) action frame which the AP uses to inform STAs within its BSS about the AP's sleep length. In addition, a function of the PSAP action frame is that STAs enter the sleep state after receiving the PSAP action frame. The proposed control method avoids the postponement of beacon transmission and reduces the power consumption in an OBSS environment, as compared to the conventional control method. Numerical analysis and computer simulation reveal that the newly proposed control method conserves power as compared to the conventional control method. The proposed control method achieves the minimum consumed power ratio at the AP, which is 44% as compared to the standard, when the beacon interval is 100ms and the sleep length is 60ms, even if the number of neighboring APs in an OBSS environment is increased.

IP 네트워크를 기반으로 하는 무선망 통합 관리 시스템 설계 및 구현

The hand over between different radio access networks, especially where their coverage overlaps, suffers various complications since the different access networks provide different service characteristics. In this paper, it is about the system which can control the wireless LAN network management system and the wireless LAN access point of variety vendor which is in different areas. Successful development of mobile sink wireless LAN network management system which supports multi-vendor devices and have center-local interoperability structure. In proposed system, speed of the mobile station give about 10% improvement when the map domain size is 5 than the existing system. Through a data plane and management system of message way, it give a stability system and consistency network.

1A2-F19 無線LANアクセスポイントからの受信信号強度を利用した複数階層環境における位置推定法の検討

This paper proposes a method for localization of a mobile wireless client, such as smart mobile phone, in a multistory building using strength of received signals from wireless LAN access points. This method uses public wireless LAN access points which are settled three-dimensionally in the building. The method supposes that humans and robots do not change height of the mobile client on each floor in the building when they move the mobile clients. The position of the mobile client on the floor and the floor number in the building are estimated simultaneously. Experimental results show feasibility of the proposed method.

1A2-G20 LANケーブルを敷設するためのロボットの開発

This paper is a thing about the development of a robot laying a LAN cable and access point for ad hoc network construction in the closedown space. Electric waves of an underground shopping center or a building are hard to arrive, therefore, closedown space is the space that wireless communication has difficulty. It is necessary to fix the environment that can perform wireless communication so that a rescue robot can perform exploration activity easily in this space. Therefore I build the ad hoc network by wired LAN and wireless LAN.

Power Saving Control for Battery-Powered Portable WLAN APs

This paper proposes a power saving control function for battery-powered portable wireless LAN (WLAN) access points (APs) to extend the battery life. The IEEE802.11 standard does not support power saving control for APs. To enable a sleep state for an AP, the AP forces the stations (STAs) to refrain from transmitting frames using the network allocation vector (NAV) while the AP is sleeping. Thus the sleep state for the AP can be employed without causing frame loss at the STAs. Numerical analysis and computer simulation reveal that the newly proposed control technique conserves power compared to the conventional control.

Using MPEG-21 for cross-layer multimedia content adaptation

This paper presents a cross-layer model— formulated using interoperable description formats—for the adaptation of scalable H.264/MPEG-4 AVC (i.e., SVC) content in a video streaming system operating on a Wireless LAN access network without QoS mechanisms. SVC content adaptation on the server takes place on the application layer using an adaptation process compliant with the MPEG-21 Digital Item Adaptation (DIA) standard, based on input comprised of MPEG-21 DIA descriptions of content and usage environment parameters. The latter descriptions integrate information from different layers, e.g., device characteristics and packet loss rate, in an attempt to increase the interoperability of this cross-layer model, thus making it applicable to other models. For the sake of deriving model parameters, performance measurements from two wireless access point models were taken in account. Throughout the investigation it emerged that the behavior of the system strongly depends on the access point. Therefore, we investigated the use of end-to-end-based rate control algorithms for steering the content adaptation. Simulations of rate adaptation algorithms were subsequently performed, leading to the conclusion that a TFRC-based adaptation technique (TCP-Friendly Rate Control) performs quite well in adapting to limited bandwidth and varying network conditions. In the paper we demonstrate how TFRC-based content adaptation can be realized using MPEG-21 tools.

Spontaneous mobile device authentication based on sensor data

Small, mobile devices or infrastructure devices without user interfaces, such as Bluetooth headsets, wireless LAN access points, or printers, often need to communicate securely over wireless networks. Active attacks can only be prevented by authenticating wireless communication, which is problematic when devices do not have any a priori information about each other. In this article, we describe three different authentication methods for device-to-device authentication based on sensor data from various physical out-of-band channels: shaking devices together, authentication based on spatial reference, and transmission via visible laser.

Unified storage systems for distributed Tier-2 centres

The start of data taking at the Large Hadron Collider will herald a new era in data volumes and distributed processing in particle physics. Data volumes of hundreds of Terabytes will be shipped to Tier-2 centres for analysis by the LHC experiments using the Worldwide LHC Computing Grid (WLCG).In many countries Tier-2 centres are distributed between a number of institutes, e.g., the geographically spread Tier-2s of GridPP in the UK. This presents a number of challenges for experiments to utilise these centres efficaciously, as CPU and storage resources may be subdivided and exposed in smaller units than the experiment would ideally want to work with. In addition, unhelpful mismatches between storage and CPU at the individual centres may be seen, which make efficient exploitation of a Tier-2′s resources difficult.One method of addressing this is to unify the storage across a distributed Tier-2, presenting the centres' aggregated storage as a single system. This greatly simplifies data management for the VO, which then can access a greater amount of data across the Tier-2. However, such an approach will lead to scenarios where analysis jobs on one site's batch system must access data hosted on another site.We investigate this situation using the Glasgow and Edinburgh clusters, which are part of the ScotGrid distributed Tier-2. In particular we look at how to mitigate the problems associated with ‘distant’ data access and discuss the security implications of having LAN access protocols traverse the WAN between centres.

A Planar Shaped-Beam Antenna for Indoor Wireless LAN Access Points

A planar antenna is described that is made up of a line source embedded in a structure containing a metal reflector and a dielectric layer coated with metal strips. We have fabricated and measured the radiation characteristics, including the return loss and radiation pattern. In addition to the experimental studies, the rigorous mode-matching method incorporating the equivalent principle was employed to calculate the electromagnetic fields in the structure and the far-field radiation pattern, as well. Besides, the sensitivity analyses for the radiation pattern against the variations on the structure parameters and relative dielectric constant were carefully carried out. The good agreement between the measured and calculated results was found. Combining the leak-waves and space-wave radiating from this structure, such a linearly polarized antenna can radiate a rectangular footprint of uniform electric-field strength, with 9% bandwidth around 11.4 GHz.

IEEE 802.21 enabled mobile terminals for optimized WLAN/3G handovers

Wireless LAN hotspots are becoming widely spread. This, combined with the availability of new multi-mode terminals integrating heterogeneous technologies, opens new business opportunities for Mobile Operators. Scenarios in which 3G coverage is complemented by Wireless LAN deployments are becoming available. Therefore all IP based networks are ready to offer a new variety of services across heterogeneous access. However, to achieve this, some aspects still need to be analyzed. In particular, how and when to execute handovers in order to minimize service interruptions and maximize the use of the most appropriate technologies according to user's preferences (for example, a user may prefer to use a lower cost technology if available). This paper presents a simulation study of handover performance between 3G and Wireless LAN access networks. The mobile devices are based on the IEEE 802.21 cross layer architecture and use Wireless LAN signal level thresholds as handover criteria.

Introducing a decision tree-based indoor positioning technique

Positioning a user is an essential ingredient of a location-based system. For the outdoor positioning, GPS is practically used. For the indoor positioning, Active Badge, BAT, Cricket, and so on have been introduced. These methods are very accurate but require special equipments dedicated for positioning. Instead of using special equipments, using existing equipments is more economical. For this reason, positioning methods of using existing wireless LAN access points have recently been introduced. Among the methods employed by them, the fingerprint methods are the most promising. Probabilistic method, K-NN (Nearest Neighbor), and Neural networks are the techniques used by the most location fingerprinting. We are proposing a new technique which is more efficient than these three. Our technique builds a decision tree during the off-line phase and determines a user’s location referring to the tree. Time complexity analysis and experimental accuracy analysis of the proposed technique are presented in this paper.

To transfer or not to transfer – Service handovers in wireless LAN systems with imperfect movement estimation

In today's networks, mobile terminals may be provided with advanced services. In order to avoid re-initialization from scratch after a handover, the so-called context of these services may either be transferred to the new Wireless LAN access point, or the respective data stream may be forwarded from the service instead. However, committing context transfers for fast terminals infers unnecessary expenses, the same is true for slow nodes with respect to the forwarding method. In this paper, we compare a default decision strategy to the theoretical optimum – that would require perfect prediction of the time to the next handover – as well as to the performance that can be reached with a certain inaccuracy of the prediction.