Wireless Local Area Network Networks Research Articles

Performance analysis of integrated WLAN-WiMAX-UMTS networks for multimedia applications

Next Generation Wireless networks (NGWN) are the integration of different types of available wireless networks. These integrated networks will provide seamless connectivity for multimedia user applications. Among various wireless networks, the networks such as Wireless Local Area network (WLAN), Worldwide Interoperability for Microwave Access (WiMAX) and Universal Mobile Telecommunications System (UMTS) have their own unique characteristics and support for wide range of multimedia user applications. So, the integration of these networks and their performance analysis in respect of Quality of Service (QoS) is a major concern nowadays. Hence, this paper deals with the integration of WLAN, WiMAX and UMTS networks by considering QoS parameter. Further, the integration of these networks are analyzed with loose coupling and tight coupling architecture along with and without QoS. Furthermore, the performance analysis of the above mentioned integrated network for multimedia applications is also done. The simulation is performed through Opnet simulator.

Coexistence of WLAN Network With Radar: Detection and Interference Mitigation

Coexistence between 802.11 wireless local area network (WLAN) and radars operating in co/adjacent channel scenarios (notably 5GHz) is a problem of considerable importance that requires new innovations. We propose a modified Wi-Fi link design that mitigates the interference from a pulsed search radar such that the WLAN network continues to operate outside the exclusion region. For low density parity check encoding adopted in high throughput WLANs such as 802.11n and.11ac, the modified receiver includes a new interleaver and a log-likelihood ratio (LLR) mapping function to mitigate the impact of radar interference. Two detection approaches are proposed to detect the radar pulse interference to Wi-Fi; time domain cyclic prefix auto-correlation detection and frequency domain data subcarrier based detection. The detection approaches are derived analytically and their performances are evaluated via simulation. We investigate the impact of interleaver length and LLR mapping function parameters via simulations to obtain the desirable frame error rate. Under the known radar pulse arrival at the Wi-Fi receiver, the modified system can significantly mitigate the radar interference for all interference to noise ratio (INR) values by using the frame interleaver. Using the radar pulse detectors in the system, the modified system can mitigate the interference at high and low INRs, while it can partially mitigate the interference in the range of 3<INR<30 dB, especially at higher modulation and coding scheme.

Intra-flow Contention Scheme for Improving QoS in WLAN

With the increasing popularity of wireless local area network(WLAN),the demand for multimedia services encompassing VoIP, multimedia streaming and interactive gaming is increasing rapidly. The real-time services require stringent Quality of Service (QoS) guarantees for effective communication. While a lot of research has dealt with providing QoS support for real-time services in traditional wired networks, the shared and broadcast nature of the wireless medium necessitates the design of new solutions for wireless networks. In wireless networks, unlike wired networks, the communication from one node will consume the bandwidth of the neighboring nodes and hence the shared bandwidth can be easily over-utilized. Therefore, to provide an acceptable level of QoS for the real-time services, it is necessary to control the utilization of the shared bandwidth. In this paper , we propose an efficient admission control scheme named Intra-flow contention scheme with CAC-OLSR routing protocol for WLAN networks which aims at preserving the QoS for all the admitted flows by employing a low overhead threshold mechanism. We describe several alternatives for the design of IAC and compare the performance of these alternatives using simulation results.

IEEE 802.11ax: Challenges and Requirements for Future High Efficiency WiFi

The popularity of IEEE 802.11 based wireless local area networks (WLANs) has increased significantly in recent years because of their ability to provide increased mobility, flexibility, and ease of use, with reduced cost of installation and maintenance. This has resulted in massive WLAN deployment in geographically limited environments that encompass multiple overlapping basic service sets (OBSSs). In this article, we introduce IEEE 802.11ax, a new standard being developed by the IEEE 802.11 Working Group, which will enable efficient usage of spectrum along with an enhanced user experience. We expose advanced technological enhancements proposed to improve the efficiency within high density WLAN networks and explore the key challenges to the upcoming amendment.

Location Fingerprinting Technique for WLAN Device-Free Indoor Localization System

Device-free indoor localization (DFIL) system can locate the position of human body in the indoor environment by observing the changes in the received signal strength indicator (RSSI) of the wireless local area network (WLAN). The accuracy of a DFIL system is depreciated, as the change in the indoor environment due to furniture and other infrastructure movement. This paper investigates the development of testbed of the WLAN network for measuring the RSSI in various indoor environment, as the initial step for designing the fingerprinting-based algorithms for WLAN network. The database of RSSI fingerprint is created initially and then a fingerprint-based algorithm is developed for locating the position of a human body in the indoor environment. The localization algorithm tests the minimum distance in the RSSI values related to the different test points in the indoor environment. This work further demonstrates that how the fingerprints of RSSI are collected and which network configurations generate the most reliable RSSI measurement. For the first phase of designing the testbed, the configurations of different equipment and various tools are elaborated in the indoor environment. For the second phase the RSSI is measured in different propagation indoor environment. The extensive experiments were performed that allow quantification of how changes in an environment affect accuracy. Thus, it is demonstrated that each link offers a viable approach to developing a more robust system for device-free localization that is less susceptible to changes in the environment.

Dual Band Triangular Microstrip Antenna for WLAN/WiMAX Applications

A novel and compact dual-band coaxial-fed triangular microstrip antenna for Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) applications with Koch boundary is presented. The proposed antenna consists of a triangular radiating patch with two U-Slots, Koch boundary, and partial ground plane. The antenna with Koch fractal boundary is able to generate an impedance bandwidth of -10 dB to cover the frequency bands of WLAN (2.32 – 2.44 GHz) and the WiMAX (3.46 – 3.58 GHz). Owing to the characteristics of gain, radiation pattern, and improved return loss, the proposed antenna is quite good for heterogeneous communication systems with WLAN and WiMAX radio networks. The overall dimension of the antenna is 43mm×40mm×1.6mm.

Network Planning for 80211ad and MT-MAC 60 GHz Fiber-Wireless Gigabit Wireless Local Area Networks Over Passive Optical Networks

We present a study concerning the network planning of 60 GHz gigabit wireless local area networks (WLANs) over existing passive optical network (PON) infrastructures. Two fiber-wireless configurations for gigabit WLAN network formations are investigated: i) the Radio & Fiber (RF and ii) the Radio-over-Fiber (RoF) paradigm that employs several remote access units operating under the medium-transparent MAC (MT-MAC) protocol, hence termed as the MT-MACover- PON approach. Simulation-based throughput and delay results are obtained for both network scenarios, revealing the dependence of the 60 GHz enterprise network performance on several network-planning parameters such as load, traffic shape, number of optical wavelengths in the backhaul, and optical backhaul fiber length, highlighting in each case the prevailing architecture. Based on the respective findings we also study a hybrid multitier architecture, termed the GPON-plus-MT-MAC approach, that fuses the abilities of both the RoF and R&F architectures in order to optimally combine their properties and set a framework for next-generation 60 Ghz fiber-wireless networks.

Cloudlet- and NFV-based carrier Wi-Fi architecture for a wider range of services

Over the past few years, Wireless Local Area Networks (WLANs) have been extensively deployed and have significantly evolved. However, the deployment of large-scale WLAN still presents management issues. Moreover, while newer WLAN technologies and services have been emerging at a prolific rate, the architecture of WLAN networks has been quite static and has seen difficulties to evolve. In this paper, we present a novel architecture for carrier-managed WLAN networks which leverages Network Function Virtualization concepts and virtualization technology in general. It is based on a WLAN Cloudlet which offloads MAC layer processing from access points and consolidates network functions and value-added services. All these functions and services are based on software instances. This brings more flexibility and adaptability and allows operators to easily implement new services while reducing CAPEX/OPEX and network equipment costs (e.g., access points).

On the authentication and re‐authentication protocols in LTE‐WLAN interworking architecture

AbstractFor mobile users, interworking environment composed of Long Term Evolution (LTE) and wireless local area network (WLAN) has become a practical consideration. As a prevalent technology, LTE has desirable features that support high data rate, mobile capabilities, good quality of service and wide coverage area. On the other hand, WLAN network provides higher bit rate but weaker mobility support. Additional features such as cost effectiveness on covering signal‐deadzones of LTE networks and its plentiful bandwidth for better good quality of service make the WLAN a complementary solution for LTE networks. Accordingly, the combination of both technologies would provide better system with higher privilege to both users and service providers. Recent development in LTE‐WLAN interworking has led to a need of authentication protocols that can provide secure and seamless handover process among such networks. Several studies have modified the existing authentication protocols, but they are limited to 3G‐WLAN interworking architecture. Besides, most of the existing authentication schemes are complex and vulnerable to network attacks (e.g. user identity disclosure). Extensible Authentication Protocol with improved authentication and key agreement protocol is introduced in this paper to present the new inter‐re‐authentication and intra‐re‐authentication protocols specified for the LTE‐WLAN interworking architecture. The proposed protocols are verified using Automated Validation of Internet Security Protocols and Applications, and the performances are evaluated in terms of energy consumption, authentication delay and signalling cost. The results indicate that the proposed protocols are more secure and efficient compared with standard protocols. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Transmission priority scheme with adaptive backoff technique in fiber-wireless networks

This paper considers the realization of fiber-wireless (Fi-Wi) networks using the gigabits passive optical network (GPON) and the infrastructure-based wireless local area network (WLAN). The bottleneck of such hybrid system is the WLAN where interference limits the performance. As such, we focus on enhancing the WLAN performance by analytically deriving the optimum contention window (CW) sizes of access points (APs) and wireless users (WUs), respectively. An adjustable transmission priority factor is introduced to allow uplink-downlink transmission fairness. Further, an adaptive backoff technique using information from monitoring the GPON and WLAN networks is proposed. Simulations show the CW sizes of all WUs are maintained within a standard deviation of 1.5% at a cost of a 3% loss in throughput due to the effect of convergence and other estimates.

An analysis of the dependence of the electromagnetic exposure level in indoor environment on traffic direction, instantaneous data rate and position of the devices in a WLAN network

The assessment of the exposure levels of humans in areas covered by Wireless Local Area Networks (WLANs) is a complex task. This is mainly due to the quasi-stochastic nature of the signals. With recently developed weighting procedures, realistic results were obtained for the electromagnetic field strength emitted by wireless emitting devices. Present work focuses on three main factors that influence the exposure level and follow their impact on the field strength. The original approach, that of experimental determination of the instantaneous data rate of transmission that is synchronized to the field level reading made by a time–amplitude measurement method, was able to detect some previous erroneous findings – that the duty cycle of transmission is mainly influenced by the data rate and therefore the prediction of the exposure level may be based on the data rate value evolution solely. It is shown here that only a multi-variable analysis based on specific developed experimental techniques is able to provide proper prediction capabilities when it comes to Wireless Fidelity (Wi-Fi) signals behavior in specific environments.

Modeling and Evaluation in an Interworking of WLAN and WiMAX Network

The complementary characteristics of Worldwide Interoperability for Microwave Access (WiMAX) and IEEE 802.11 Wireless Local Area Network (WLAN) networks make them attractive for integration to offer the best of both technologies. However, in order to make the integration effective, the in-depth mobility study by simulation is necessary. This paper addresses the simulation models for mobility management procedures in an interworking of WiMAX and WLAN network for the various integration scenarios. The mobile multihomed node models of WiMAX and WLAN interfaces are developed and simulated in various traffic environments and network integration topologies including group mobility and MANET. The simulation results show that the developed models are useful for mobility studies in various integration wireless networks.

INOVASI PEMBELAJARAN BERBASIS VIDEO STREAMING DAN JARINGAN TELEKOMUNIKASI DI PERGURUAN TINGGI

In certain study programs, especially electrical engineering, informatic engineering, information system and the like there are courses in computer program design. In this case, lecturer provides the learning how to design a computer program with a specific programming language systematically and sequentially, step by step. To increase the role of lecturer of the computer program design in a college, requires the implementation of a multimedia technology that can guarantee the systematic and sequential learning, step by step, especially when in a certain condition, the student is unable to attend the computer program design course given lecturer in the class. Although it may be found the equivalent tutorial on the internet, but the student still need the learning from lecturer. On the other hand, the lecturer of the computer program design is hard to repeat the explanation of the course given at the previous meeting to the absent student in the class, as it can spend the time already allocated for the next course explanation. In this paper provided a solution to overcome these problems by creating a streaming video provider server of computer program design courses that have been given lecturers at previous meeting in class. Access to streaming video is limited, accessible only to students who follow the course of computer program design through WLAN network on the college where the student is in college and when the end of the semester, the database server containing that streaming video is deleted by the system automatically so it can be filled with video streaming of next semester lectures, so as to save bandwidth and server memory. The explanation in this paper is limited to how to access streaming video in Wireless Local Area Network (WLAN). The methodology used is to simulate WLAN network with one computer as Learning Server and two laptops as client terminal. Keywords: Learning Server, Wireless LAN (WLAN), program

Primary Traffic Characterization and Secondary Transmissions

Channel idle time distribution based secondary transmission strategies have been studied intensively in the literature. Under various performance metrics, the ultimate performance of secondary devices are eventually dictated by the presumed channel idle time distribution. Such distributions can take any arbitrary form in practice. In this work, we study idle time distributions in wireless local area networks (WLAN) using large amount of the channel idle time data collected in real-world WLAN networks. We demonstrate with experimental data that the channel idle time distribution can be closely modeled by hyper-exponential distribution. Furthermore, one can treat the primary packet arrival process as a semi-Markov modulated Poisson process. Several secondary transmission strategies are discussed under this model. It is shown that using only one hyper-exponential distribution, the secondary user can achieve a desirable performance when the primary packet arrival process is stationary. However, experimental data suggests that in practice, this process is not stationary and the secondary user can experience a large performance loss with stationary transmission strategy. We propose a novel transmission strategy that achieves suboptimal secondary user performance when the idle time distribution is not stationary. The performances of secondary transmission strategies are demonstrated using experimental data.

A Threshold Based Handover Triggering Scheme in Heterogeneous Wireless Networks

The widespread popularity of Wireless Local Area Network (WLAN) is recognized as an effective approach to complementing cellular networks for the high data rate and cost effective connectivity delivered to mobile users. Efficient handover and offloading schemes for integrated WLAN and cellular networks, referred to as Heterogeneous Wireless Networks, have thus attracted lots of attentions from both academia and industry. This paper proposes a novel Multiple-Threshold based Triggering (MTT) scheme for Cellular-to-WLAN handover control. Aiming at minimizing the probability of handover failures and unnecessary handovers, three thresholds are calculated based on a variety of network parameters such as system performance requirements, radius of the WLAN coverage, user mobility and handover delays. The thresholds are then compared against the predicted user residence time and estimated channel holding time inside WLAN to make vertical handover decisions (VHDs). Simulations were carried out to evaluate the effectiveness of MTT and results show that MTT minimizes handover failures and avoids unnecessary handovers in integrated cellular and WLAN networks, thus providing satisfactory Quality of Service (QoS) to users and improving system resource utilization.

Signal Strength Ratio Based Vertical Handoff Decision Algorithms in Integrated Heterogeneous Networks

In this paper, we propose the signal strength ratio (SSR) based vertical handoff (VHO) algorithms and the averaged received signal strength (ARSS) based VHO algorithms for integrated networks of wireless local area network (WLAN) and 3G network. The performance of our proposed VHO algorithms with hysteresis and dwell timer approaches has been investigated for two different topologies of integrated heterogeneous network. Two different network topologies consider two different types of radio cell arrangement. A mobile terminal (MT) is moving within the coverage area of WLAN and 3G with constant velocity. The received signal strength at the MT of interest is measured at different sampling instant. The received signal strength with other additional parameters is used to determine the condition of VHO. We evaluate the decision delay, and the number of vertical handoffs between WLAN and 3G network using the proposed VHO algorithms. We compare the performance of our proposed VHO algorithms with existing RSS based VHO algorithm. Our proposed SSR and ARSS based VHO algorithms provide less decision delay as compared to existing RSS based VHO algorithm. Further, ARSS with dwell timer based VHO algorithm provides better performance than other VHO algorithms.

Performance analysis of WIMAX-WLAN overlay networks using modified dynamic speed sensitive call admission control

The efficient call admission control (CAC) plays an important role in effective utilisation of integrated heterogeneous networks such as IEEE 802.11/wireless local area networks (WLANs) and IEEE 802.16/wireless microwave access (WiMAX). In this paper, modified dynamic speed sensitive CAC (MDSSCAC) is proposed and analysed for loose, tight and hybrid ring–based WiMAX-WLAN overlay networks. MDSSCAC effectively utilises available resources by admitting calls to proper network and enhances Quality of Service by dynamically varying bandwidth reservation for handoff calls based on traffic prediction. MDSSCAC assigns preference for the calls to admit either in WiMAX or in WLAN network based on velocity, location and service type of call. MDSSCAC avoids unnecessary handoff initiated by high–velocity users and effectively balances load between WiMAX and WLAN networks. MDSSCAC yields better performance compared with the existing speed sensitive CAC (SSCAC) and dynamic SSCAC (DSSCAC). The hybrid coupling provides better performance compared with other coupling.

Performance Analysis of Multi Traffic over Multi Rate EDCA of WLAN Network

Enhanced distributed channel access (EDCA) is used for transmitting good quality of service of multimedia traffic in wireless local area network (WLAN). Applications like Constant bit rate (CBR), file transfer protocol (FTP) and voice over internet protocol (VoIP) are used in wireless LAN network. Audio data is assign as high priority (AC_VO) and other such as CBR & FTP type of data are assigned as low priority (AC_BE) in IEEE 802.11b network. G.711 provides a very good perceived audio quality in comparison to other audio CODECs. The G711 codec is used in VoIP call with 20 msec of audio data. In this paper, analysis of the effects on CBR& FTP traffic with increased call rate of VOIP and payload sizes of CBR & FTP traffic in WLAN environment for real time applications are made. Jitter buffer used in RTP protocol is improving the quality of service (QoS) of multi traffic in comparison to RTP protocol without jitter buffer.

Vertical Handover Over Intermediate Switching Framework: Assuring Service Quality for Mobile Users

Ensuring quality of service (QoS) for the mobile users during vertical handover between IEEE 802.11 wireless local area networks (WLAN) and data network provided by Ultramodern Telecommunication Systems (UMTS) is one of the key requirements for seamless mobility and transfer of existing connections from one network to another. QoS fulfillment is a complex problem and requires participation of both the mobile users as well as the connection networks. The QoS assurance criteria for existing connections can be affected by fluctuations of data rates when a user moves from the high speed WLAN network to the low speed UMTS network, even in the presence of another WLAN network in its vicinity. This can happen if the alternate WLAN network is highly loaded. Therefore handover from a high speed network to a low speed network should be avoided, whenever possible. This paper proposes a QoS based handover procedure that prioritizes the existing connection over the new connections so that rate fluctuations due to handover can be avoided if there exist another WLAN network in the range of the mobile user. Whenever the possibility of handover is detected, a pre-handover bandwidth reservation technique is used to reserve bandwidth at the alternate WLAN networks to avoid QoS degradation. The proposed scheme is implemented in Qualnet network simulator and the performance is analyzed and compared with traditional handover techniques.

Cognitive beamforming based smart metering for coexistence with wireless local area networks

The ZigBee network has been considered to monitor electricity usage of home appliances in the smart grid network. Zig-Bee, however, may suffer from a coexistence problem with wireless local area network (WLAN). In this paper, to resolve the coexistence problem between ZigBee network and WLAN, we propose a new protocol constructing a cognitive smart grid network for supporting monitoring of home appliances. In the proposed protocol, home appliances first estimates the transmission timing and channel information of WLAN by reading request to send/clear to send (RTS/CTS) frames of WLAN. Next, based on the estimated information, home appliances transmit a data at the same time as WLAN transmission. To manage the interference between WLAN and smart grid network, we propose a cognitive beamforming algorithm. The beamforming algorithm is designed to guaranteeing zero interference to WLAN while satisfying a required rate for smart metering. We also propose an energy efficient rate adaptation algorithm. By slowing down the transmission rate while satisfying an imperceptible impact of quality of service (QoS) of the receiver, the home appliance can significantly save transmit power. Numerical results show that the proposed multiple antenna technique provides reliable communications for smart metering with reduced power comparing to the simple transmission technique.