WLANs

This paper presents various security features and configurations commonly implemented in WLANs and their aggregated security levels and then proposes a model that enables implementation and evaluation of WLAN security. KeywordsWLAN Security model; WLAN Security; WLAN attacks & Vulnerabilities; WLAN Security Features Selection; WLAN Security Measurement;

In this work the propagation of radio waves at 2.4 GHz in NLOS conditions has been studied. The study was carried out using two transmitters operating on different standards: 802.11g (D-Link) and 802.11n (TrendNet). The experiments were carried out under different scenarios in order to investigate the effect of the walls on signal propagation. Experimental results were processed using statistical methods and were compared with "log-distance" and free space models and with the network simulation programme "Aerohive online planner" results. A new signal prediction model, which allows predicting signal propagation depending on the number of walls, was created. In this work 802.11g and 802.11n standards were also compared. The results can be used to further investigate radio wave propagation in indoor NLOS conditions and in the development of wave propagation models.

Wireless (Wi-Fi) networks based on IEEE 802.11 1 family of standards have been spreading its coverage last years and this trend is expected to grow. Every day more and more people use this type of networks to access Internet, company or other types of networks. Today's wireless networks are vulnerable in many ways (rogue access points, hijacking sessions, eavesdropping, illegal use, unauthorized access, denial of service attacks, floods, stealing data and other types of misuse and attacks etc). People are worried about unknowingly exposing their computers to illegal access through the air, from an undefined location. On wired networks the intruder can access by wire, but in wireless environments the intruder can access the network from anywhere in the neighborhood. At the present time there are IDS's but mostly deployed on wired networks, and based on rules and signatures of already known and analyzed intrusions. These systems can't answer the demand in environments where new intrusions are occurring every day due their legacy IDS's limitations. Intrusion detection agent presented in this paper is part of WIDSwireless intrusion detection system. WIDS Agent is software installed on mobile computer device. It detects intrusions and attacks by analyzing traffic and making conclusions and denies it. It works as standalone module or coupled (in contribution) with WIDS Sensor and Server that are also part of this system. Position of application is on personal computer (PC), including Pocket PC (PPC), other PDA devices and similar computerized and mobile devices. This system has capabilities such as: self learning, autonomy and decision, self-decision and self defense including alerting. This is multidimensional system in development which is intended to cover most of wireless networks specific vulnerabilities and intrusion. It should work in real-time and defend user i.e. his computer or system against majority of intrusions nevertheless of fact if they are already known or new kind of attacks. System is integrated in clients and performs local data collection and filtering, works as local detection engine cooperating with neighboring WIDS agents (cooperative detection engine). It provides local response and/or global response against intrusion. Also, this system works in the closest relationship with firewall software and devices, antivirus software, network management and other security tools.

Network technologies are traditionally based on wireline solutions. But the introduction of the IEEE 802.11 standards have made a huge impact on the market such that laptops, PCs, printers, cellphones, and VoIP phones, MP3 players in our homes, in offices and even in public areas have incorporated the wireless LAN technology. Wireless broadband technologies nowadays provide unlimited broadband access to users which were previously offered only to wireline users. In this paper, we review and summarize one of the emerging wireless broadband technology i.e. IEEE 802.11,which is a set of physical layer standard for implementing wireless local area network computer communication in the 2.4,3.6,5 and 60GHz frequency band. They fix technology issues or add functionality which is expected to be required by future applications. Though some of the earlier versions of these technologies are obsolete (such as HiperLAN) now but still we have included them in this review for the sake of completeness.

De nos jours, la technologie de réseau sans fil est incontournable car elle fournit la possibilité d’accéder à ses informations personnelles ou professionnelles partout et à tout moment. Dans un contexte d’exigences croissantes en matière de réseau sans fil de rapidité et de sécurité, la norme du Wifi est en constante optimisation. Aujourd’hui par exemple, la technologie 802.11n offre un débit pouvant atteindre 300 Mbps, soit six fois plus élevé que le débit fourni par les réseaux sans fil 802.11 a/b/g.

Wireless local area network (WLAN) has been widely used in many sectors. The popularity gained is due to many reasons, such as ease of installation, installation flexibility, mobility, reduced cost-of-ownership, and scalability. However, regardless of the benefits mentioned above, WLAN have some security threats, in which anyone who use it or intend to use it should be aware. This paper begins by introducing the concept of WLAN. The introductory section gives brief information on the WLAN components and its architecture. In order to examine the WLAN security threats, this paper will look at Denial of Service, Spoofing, and Eavesdropping. This paper will also tell about the reasons of loss of data and the security measures that are involved to reduce the loss of data from hackers by using the data confidentiality and prevention and access control mechanism.

In this article, a dual-band WLAN/ultrawideband (UWB) printed wide slot microstrip-fed antenna is presented for multi-input multi-output (MIMO)/diversity applications. The proposed antenna consists of a U-shaped patch, a T-shaped monopole path, and a pentagonal wide slot in the ground plane. The antenna is designed to cover both the WLAN (2.4-2.485 GHz) and UWB (3.1-10.6 GHz) ranges, with value of S 11 below À10 dB. The antenna is constructed on a FR4 substrate with overall dimensions of 28 Â 28 Â 1 mm 3. It is shown that the proposed dual-band antenna is suitable for diversity polarization applications. The simulation results show that the different configurations of the antenna in the MIMO/diversity have good S-parameters over the operating frequency bands. The simulation and measured results of the proposed dual-band antenna as well as that of the MIMO/diversity antenna configuration agree well. V C 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:461-465, 2013; View this article online at wileyonlinelibrary.com.

The company mining of Guemassa, subsidiary of Managem, operates since several years the zinc, lead, and copper underground deposit of Draa Sfar, at 10 km to the Northwest of Marrakech. Original volcano-sedimentary, this deposit is in a vein form, with an extension of several hundreds of meters, an average power of a few meters, and a sub-vertical dip. Mineralization remains open vertically, and exploitation has now exceeded the 1000 m of depth. At these levels of depth, aspects related to underground logistics take a special importance, and the time lost to disseminate an information (for example failure of a machine in a work site) becomes very penalizing. This is the reason why Managem wanted to examine the possibilities to develop a reliable and effective communication infrastructure in the mine. Aside the gains in terms of security and productivity of the operation, such a network is also the preliminary step to any form of future automation of some aspects of the underground mining. The issues of such a system of communication are consequently essentials.

The study focuses first on the analysis of the various possible technologies for the development of a communications network. These technologies are on the one hand compared on a purely theoretical level, on the other hand a bibliographical study allows to identify which are most common in mines underground today, and for what types of applications. The Wi-Fi technology appears to be the best suited to our case.

This technology is then analyzed in more detail. A network architecture has been proposed, based in particular on underground tests aim to determine the scope of the signal emitted by an antenna in the mining drifts. This architecture has led to a quantification of the cost of developing a network for an application in the deepest part of the mine of Draa Sfar, or for an experimentation in the significantly smaller Koudiat Aicha mine.

At the same time, the study served to identify the gains associated with the development of such a network of communication , and to quantify these gains at each time that productivity data were available (gains in terms of time intervention on failures for example).

Anyway the work is in french, but if you have any questions you can contact me, it will be a pleasure to discuss.
Mine automation is the present and future for mining industries, consequently for the world too.

Cuando se intenta configurar una red de área local inalámbrica (WLAN) de forma manual con los procedimientos tradicionales más difundidos, se obtiene un fallo crítico que arroja un mensaje «error for wireless request "set encode" (8b2a)» si el punto de acceso inalámbrico
(WAP) protege la red con sistemas WPA o WPA2. Esto, se debe a que los procedimientos tradicionales basan su método de configuración en redes protegidas con el antiguo sistema de protección WEP declarado obsoleto hace más de una década, a raíz de sus conocidas debilidades criptográficas. Este estudio se concentró en entender el funcionamiento exacto de las redes inalámbricas, sus protocolos, sistemas de protección y mecanismos de transmisión de datos, para obtener así, el procedimiento más adecuado para lograr una configuración
propicia cuando se prescinde por completo del entorno gráfico.

This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of-31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed.

802.11ac is an interesting standard of IEEE bringing multiple advantages than its predecessor 802.11n. 802.11ac is faster and more scalable version of 802.11n offering the capabilities of wireless Gigabit Ethernet. 802.11ac will enable access points (AP) to support more STAs with a better experience for clients and more channel bonding increasing from a maximum of 40 MHz with 802.11n up to 80 or 160 MHz with 802.11ac standard. In this paper, we analyze and evaluate the 802.11ac performance using NS3 simulator (v3.26) relying on several features like channel bonding, modulation and coding schemes, guard interval and frame aggregation. Then, we presentthe effect of the variation of d istance between STAs and AP on the network performance in term of throughput. Finally, we capture the most relevant simulations outcomes and we indicate some research challenges for the future work. 1. INTRODUCTION The IEEE 802.11ac is a Very High Throughput standard operating only in 5 MHz frequency band. By using 5 GHz frequency band, 802.11ac avoids consequently much of the interference due to the important use of 2.4 GHz ISM band in the three ITU regions. The new features and enhancements in the MAC and PHY layers of 802.11ac allowed this technology to achieve data rates approaching 7Gbps. 802.11ac outperform the 802.11n data rates by introducing several improvements like wider channels 80 and 160 MHz, also 256QAM modulation enhanced the number transmitted bits from six bits (64QAM) to eight bits on each subcarrier in the channel and raised the maximum number of spatial streams (SS) on the access point side to eight SSs instead of four in 802.11n while being able to transmit to multiple clients at the same time as a result of MU-MIMO feature. The study of IEEE 802.11 standard performance is the main subject of multiple researches by means of analytical models or simulation. An important analysis was first introduced in [1] as Bianchi presented the performance of wireless networks using 802.11 distributed coordination function (DCF) based on a Markovian model. Also, in [2], an analytical model was presented in order to analyze the impact of basic and RTS/CTS access mechanisms of DCF on 802.11ac throughput. The results based on the throughput equation in [2] have showed interesting outcomes about the effectiveness of RTS/CTS mechanisms when packet size increases and the importance of frame aggregation which was also studied in [2, 3]. In [4], the author presents only BER values for different modulation techniques BPSK, QPSK, 16QAM and 256QAM revealing that it is preferable using the BPSK modulation rather than 256QAM with higher BER in transmitting the data on the AWGN channel. Moreover, in [5], an overview of the main performance of both 802.11ac and 802.11n was presented where the authors noticed that, in terms of performance, the two 802.11

WLANs have become increasingly popular and
widely deployed. The MAC protocol is one of the
important technology of the WLAN and affects
communication efficiency directly. In this paper,
focusing on MAC protocol, we propose a novel
protocol that network nodes dynamically optimize
their backoff process to achieve high throughput
while supporting satisfied QoS. Distributed model
MAC protocol has an advantage that no
infrastructure such as access point is necessary. On
the other hand, total throughput decreases heavily
and cannot guarantee QoS under a high traffic load,
which needs to be improved. Through theoretical
analysis, we find that the average idle interval can
represent current network traffic load and can be
used together with estimated number of nodes for
setting optimal CW. Since necessary indexes can be
obtained through direct measurement from channel,
our scheme will not increase any added load to
networks, which makes our schemes simpler and
more effective. Through simulation comparison
with conventional method, we show that our
scheme can greatly enhance the throughput and the
QoS no matter the network is in saturated or nonsaturated case, while maintaining good fairness.

The growth of smart antennas replaced many older technologies. Likewise, this paper presents a study on design of monopole antenna array with multiband multiple-input–multiple-output (MIMO) antenna system for small mobile terminals. Many smart antennas are designed with variable sizes for many different types of uses. In those, each antenna will support particular range of frequency, and some antennas may support few range of frequencies. But the antenna design which is presented in this paper supports five different frequencies. Those are 900, 1800, 2100, 3500, and 5400 MHz, which means, the antenna designed supports five resonant modes. This antenna covers GSM850/900, DCS, PCS, UMTS, WLAN and WiMAX frequency bands.In case of proposed system, a small and compact triple-band microstrip-fed printed monopole antenna for WLAN and WiMAX will be used. The proposed antenna will have a rectangular radiating patch with “L” and “U” shaped slots and ground plane. The proposed antenna is expected to be small when compared to antenna design discussed in this paper. The proposed paper presents a study on a small and compact triple-band microstrip-fed printed monopole antenna for Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX). The antenna designed in this paper consists of a rectangular radiating patch  L- and U-shaped slots. The length of the L and U shaped slots are designed to obtain the required frequency bands—namely, WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5 GHz).

The success in the growing wireless standards can be measured by the achievement of quality of service (QoS) specifications by the designers. The IEEE802.11 wireless standards are widely accepted as  wireless technology  for wireless LAN. Efforts have been made over the years by the task group to provide adequate number of QoS enhancement schemes for the increasing numbers of multimedia applications. This paper examines the empirical performances of ad hoc wireless networks deployed on IEEE802.11 standard variants. A survey to some of the QoS schemes incorporated in IEEE802.11 wireless PHY layers were carried out. Then the  effects of this enhancement schemes in relation to data throughput and system capacity and reliability in the newest technology deployed on IEEE802.11ac standards was investigated using real time applications and simulation based approaches.

Voice over Wireless Local Area Network (VoWLAN) technology offers significant benefits that provide wireless voice applications for universities, hospitals and enterprises. Some of these primary benefits are cost efficiency, noticeable increase in productivity rate and wirelessly accessing employees anywhere.  There are two technologies that VoWLAN consist of, first is the Wireless Local Area Network (WLAN), while the second is the Voice over Internet Protocol (VoIP). Although, VoWLAN requires more  than just a WLAN; it is in need of an Internet Service Provider (ISP) to access the Internet [1, 2]. Voice call communication over Wi-Fi is another network technology that provides free calls over WLAN without the need of an ISP [3]. In this paper, we present a survey concerning voice communications over various network technologies and suggest a solution as a result of comparison between these technologies. This solution aims to  provide  a facility of making free voice calls that would only use WLAN technology without the need of a service provider. Using free bands of WLAN would provide no cost internal communications and would include the benefits of VoWLAN. The challenges that face deployment of this solution would be providing mobility and large coverage area. Therefore, WLAN will need to be extended by including several Access Points (APs).

A compact design of ultra-wideband (UWB) antenna with dual band-notched characteristics are investigated in this paper. The wider impedance bandwidth (from 2.73 to 11.34 GHz) is obtained by using two symmetrical slits in the radiating patch and another slit in the partial ground plane. The dual band-notch rejection at WLAN and X-band downlink satellite communication system are obtained by inserting a modified U-strip on the radiating patch at 5.5 GHz and embedding a pair of single rectangular split ring resonators (SR-SRR) on both sides of the microstrip feed line at 7.5 GHz, respectively. The proposed antenna is simulated and tested using CST MWS high frequency simulator and exhibits the advantages of compact size, simple design and each notched frequency band can be controlled independently by using the geometrical parameters of the corresponding resonator. Therefore, the parametric study is carried out to understand the mutual coupling between the dual band-notched elements. To validate simulation results of our design, a prototype is fabricated and good agreement is achieved between measurement and simulation. Furthermore, a radiation patterns, satisfactory gain, current distribution and VSWR result at the notched frequencies make the proposed antenna a suitable candidate for practical UWB applications.

In recent times, the use of ad hoc networks is a common research area among a researcher. Designing an
efficient and reliable network is not easy task. Network engineer faces many problems at the time of
deploying a network such as interference; Signal coverage, proper location of access point etc. channel
interference in one of them which must be considered at the time of deploying WLAN indoor environments
because channel interference impacts the network throughput and degrade the network performance.
In this experiment, we design a two WLAN BSS1 and BSS2 and investigate the impact of interference on
nodes. BSS1 contains three FTP clients and BSS2 contains two FTP client and their jobs is to upload data
to FTP Server Initially, they are far from each other. BSS1 moves toward BSS2 and after some time at
particular position both BSSs overlaps to each other. When BSSs overlaps to each other interference is
high and decrease network performance and increase upload time.

A VLAN is a logical rather than physical connection that allows grouping hosts together in the same broadcast domain, so that packets are only delivered to ports that are combined to the same VLAN. By characteristic VLAN network, we can improve efficiency of wireless network and save bandwidth. Furthermore, implementing VLAN greatly improves wireless network security by decreasing the number of hosts that receive copies of frames broadcasted by switches, so hosts holding critical data are kept on a separate VLAN. This paper compares wireless network with wireless network having VLAN deployment. The proposed Network is evaluated in terms of average throughput and delay using file transfer in heavy traffic and web browsing applications. The simulation was carried out by employing OPNET 14.5 modeler simulation and the results show that the use of VLAN via wireless network had improved the performance by decreasing the traffic resulting in minimizing delay time. In addition, implementing VLAN reduces the network throughput because the traffic that is received and forwarded has a positive relationship with throughput. Furthermore, we investigated to improve the throughput in a wireless VLAN network by using adhoc routing protocols. Evaluation, comparison of broad adhoc routing protocols like AODV, DSR, OLSR, TORA and GPR are conducted in order to show the effect of the proposed VLAN on the performance results, like throughput and delay.

Amongst other mandates of the 4th Generation of Wir
eless Networks (4G), integration and unification of
various technologies is a critical subject. In this
paper an end-to-end wireless network deployment in
a
test-bed environment is established to demonstrate
a practical model for integration of various wirele
ss
technologies used by ISPs to provide services to la
rge and small enterprise customers. The focus of th
is
research is on the Quality of Service (QoS) conside
rations in a WiFi-WiMAX integrated network. The
results show that integrated deployment does not de
teriorate throughput as compared to a standalone
WiMAX system. The throughput of approximately 967.5
kbps was observed throughout the path and
shows a steady performance across various parts of
the network regardless of the technology involved.
Numerical results also confirm that outcomes for ef
fectiveness of the QoS routines defined in the
proposed architecture are not severely affected by
the integration

A triple-band multi-input multi-output (MIMO) antenna is presented.The proposed antenna consists of a C-shaped monopole antenna that provides dual-band resonant antenna. By protruding an L-shaped parasitic strip on the ground plane, a third band as well as enhancement of the isolation between two ports in MIMO array is achieved. The proposed antenna can cover 2.1–2.6, 3.3–4, and 5.4–6 GHz, which are allocated for WLAN and WiMAX applications. The proposed triple-band antenna structure is used in different two-element MIMO arrays. Simulation results show that the S11, S12, and S22 of the MIMO arrays are independent of the position of the two-element. The results show good S-parameters, high peak gain and radiation efficiency, and stable radiation patterns among the triple-band coverage. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1321–1325, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26799

Modern technology is essential for all healthy, economic, and educational sectors. Using modern technology involves high-performance networks in terms of quality of service (QoS) parameters such as delay, throughput, bandwidth, and security. A campus network involves wire and the wireless environment with and without virtual local area network (VLAN) technology has been simulated using optimized network engineering tools (OPNET). The simulation model includes four scenarios that involve heavy-loaded File transfer protocol (FTP) and web browsing applications with two logical groups of users. The simulation results show that the VLAN overcome LAN networks in terms of bandwidth and security. This has been done by reducing the throughput in both sending and receiving levels to the confidential servers. The VLAN has also reduced the broadcast domain which results in a high-power efficiency. Moreover, the VLAN network technology has been proved to have lower values of delay in transferring files and packets than LAN network technology. In addition, VLAN technology generally has been decreased values of throughput regardless of the way of connection between servers and workstations. This, in turn, allows taking advantage of wireless connection features in terms of flexibility of installation and speed of configuration.

In this paper we reflect evaluation of Wireless Local Area Network (WLAN) standard in a vehicular environment. WLAN based on the IEEE802.11a standard in wireless user community is widespread and well known to ensure wireless communication. This standard can be used indoor environment for stationary and slowly move users. Despite this fact we analysed this wireless communication standard to understand basic performance and suitability for Intelligent Transportation Systems (ITS) providing a ubiquitous mobile INTERNET access. A wireless vehicular communication tests in real scenario usually require a large number of vehicles and testers for proper results. To derive an experimental result we used simulation/emulation tool such as National Chiao Tung University- network simulator (NCTUns).

A single layer substrate compact dual band rectangular micro-strip patch antenna with transmission line feeding is designed for Wireless Local Area Networks (WLAN) implementation. The desired antenna consists of a rectangular patch having two I-slots and a dielectric material with dielectric constant of 2.4. The use of cavity model with transmission line feed has the favor of low profile, high gain and wide bandwidth of the antenna. The antenna has overall size of 46.9 mm by 38.01 mm and gives bandwidth of about 90 MHz at resonance frequency of 2.45 GHz and that of 115 MHz at 4.1 GHz frequency with Defected Ground Structure (DGS). The antenna with DGS has return losses -21.25 dB at 2.45 GHz and -27.5 dB at 4.1 GHz where the gains are 6.70 dB for 2.45 GHz and 6.80 dB for 4.1 GHz. Finally the designed antenna has been simulated using Computer Simulation Technology (CST) microwave studio 2009 and it is comparable with manual computation results which are found to be suitable for WLAN a...

Steganography is a technology used since years for the communication of messages secretly. These secret messages are put inside honest carriers. Carriers can be digital images, audio files, video files and so on. The limitation in sending concealed longer messages has been overcoming by the inclusion of video files as carriers. Popular internet services such as Skype, BitTorrent, Google Suggest, and WLANs are targets of information hiding techniques. Nowadays, plotters are not only using the carriers but also the protocols for communication that regulate the path of the carrier through the
Internet. This technique is named Network Steganography.

IEEE802.11 have been fully understood in the networking era. Opnet with IEEE802.11 give assistance is an easily understood able simulation tool for communication researchers. However it's academic Edition have limited abilities. In this paper author have studied performance of IEEE802.11b (WLAN) using various security parameters. Author found that the throughput was decreases with respect increase in number of nodes and packet drop also increases with increase in number of nodes.

Smart home technology nowadays became more popular and wide spread world around. The communication network's appropriate coverage, flexibility and low cost made the Wi-Fi technology one of the strongest choices in this field. The main purpose of this paper is to propose a simple, flexible and low cost design of controlling home appliances and connecting other hardware using Wi-Fi network. The ability of exploiting this design and implementation in different environment and possibility of integration with other modern technology are considered the main benefit of the proposed design. The proposed system provides connecting and controlling all available devices inside home using many sensors and actuators. The monitoring process achieved by appropriate installed software on regular user computer or handheld device.

the main Theme of this project entitled communication on Adhoc (VLAN) Network is to design and implement a telephony program that uses Wi-Fi in LAN as means of communication between mobile phones. The technology for creating mobile campus network via Wi-Fi. The VLAN is a wireless local area network (VLAN) links two or more devices over a short distance using a wireless distribution method, usually providing a connection through an access point for Internet access. The technology of Mobile Virtual LAN, where multiple Mobiles used to create mobile network via Wi-Fi is discussed. In this mobile Wireless network , the single mobile is configured as Server and rest of Mobile phones as clients. The implementation goals includes the several features including, file sharing, browsing and push message notification etc.

—Wireless Local Area Networks (WLANs) have become omnipresent: WLANs are available at airports, coffee shops, university campuses, corporate environments, and homes. This surge in the popularity of WLANs motivates the study of how these networks are used. As using WLANs has become more popular an effective network monitoring has become extremely important in ensuring the proper functioning of the network. In this paper, I describe our experiences with the process of network monitoring and use of FLUKE networks OptiView for monitoring usage of WLANs, and analyse the results.

This paper presents the numerical simulations of dual band two elements Inverted-L antenna for 3.5 GHz mobile WiMAX and 5 GHz Wi-Fi operation. The proposed antenna is feed by a coaxial connector. The antenna arms effectively control the excited resonant modes for Wi-Fi and mobile WiMAX operation.
Total area occupies by the antenna is 20 mm × 30 mm. The antenna contains substantial gain with less than 0.3 and 2 dBi gain variation within the -10 dB return loss bandwidth at 3.5 and 5 GHz operating frequency respectively. In addition, the antenna has achievable bandwidth, return loss and radiation
characteristics for both frequencies. Due to the compact area occupied, the proposed antenna is promising to be embedded within the different portable devices employing 3.5 GHz mobile WiMAX and 5 GHz Wi-Fi operation.

In the 802.11 protocol, DCF can be termed as an important mechanism in order to access the medium (Channel). This scheme is a random access based scheme which has its fundamentals based upon the efficient usage of CSMA/CA protocol. The retransmission of various collided packets is effectively managed in accordance with the Binary exponential Back-off rules. The waiting time of the BEB is exponentially increased by 2 after every unsuccessful transmission. Every successful transmission sets the back-off stage to initial stage and the contention window is also subsequently set to  minimum regardless of any network conditions like the various n number of competing nodes. As the number of competing
nodes rises, it can cause substantial performance deprivation as a result of the new collisions caused. This paper highlights and investigates the various modifications possible in the basic calculating methodology of the CW size after every successful transmission and collision of the BEB algorithm and it also evaluates the performance through different simulations possible for it. This paper also throws some significant light on the comparative study conducted on the throughput, end to end delay and packet loss ratio of the investigated schemes along with conventional DCF & one –another.

This paper proposed quadruple notched frequency bands ultra-wideband (UWB) antenna. The antenna is a semicircular-shaped monopole type of a compact size 36x24 mm, covering frequency range of 3.02-14 GHz. Four rejected narrow bands including WiMAX (3.3-3.7GHz), ARN (4.2-4.5 GHz), WLAN (5.15-5.825GHz), X-Band (7.25-7.75) have been achieved using inserting slots techniques in the patch, feed line, and ground plane. The slots dimensions have been optimized for the required reject bands. The antenna design and analysis have been investigated by simulation study using CST-EM software package. The antenna characteristics including impedance bandwidth, surface current, gain, radiation efficiency, radiation pattern have been discussed.

WiFi offloading is becoming one of the key enablers to help the network operators dealing with the exponentially growing demand of mobile data. The idea of using WiFi to offload data traffic from cellular network has proposed for many years. However, the interoperability issue between the two networks needs to be enhanced so that WiFi can efficiently supplement for the cellular network in case of congestion or outage. In this paper, we propose a novel network roaming and selection scheme based on 3GPP TS 24.312 and IEEE 802.11k, u standards to enhance cellular and WiFi interworking. The proposed scheme is aimed at enhancing the network roaming and selection so that WiFi network can serve as a supplement and backup access network for the cellular not only for congestion control but also in case of unexpected network failure event. We also model and evaluate the proposed scheme in a typical HetNet with interworking WiFi access points and cellular base stations. The simulation result shows that our proposed scheme quickly detects unexpected network failure event and assists active UEs to perform handoff to preferable alternative point of access. As a result, service disruption is substantially reduced and quality of experience (downlink/uplink's throughput) is improved. Therefore, our proposed scheme can be used for a more reliable HetNet in terms of congestion control and disruption tolerance.

A small-size microstrip-fed multi-band planar monopole antenna is presented. The base of the proposed antenna is a diamond-shaped-patch (DSP) that covers the ultrawideband (UWB) frequency range. To create a multi-band antenna, several narrow strips, acting as resonance paths, can be integrated with the DSP antenna. It is shown that by removing the centre part of the DSP antenna, without distorting the UWB behavior, quarter-wavelength strips can be added to the notched region. This will not affect the dimension of the base antenna. The designed quad-band antenna has a substrate size of 16 22 mm and covers the frequency bands 1.3, 1.8, 2.4 and 3.1-10.6 GHz which includes GPS, GSM, WLAN and UWB. Dual-, triple-and quad-band antennas are simulated and good results are obtained. The antennas have omnidirectional and stable radiation patterns across all the relevant bands. Moreover, relatively consistent group delays across the UWB frequencies are noticed for the base, dual-and triple-band antennas, and slightly distorted for the quad-band antenna. A prototype of the quad-band antenna is fabricated and measured results are compared with simulated results. Index Terms-Monopole antenna, multi-band antenna, ultrawideband (UWB) antenna, wireless communication frequencies.

In this paper, we present a low complexity Quasi-cyclic-low-density-parity-check (QC-LDPC) encoder hardware based on Richardson and Urbanke lower-triangular algorithm for IEEE 802.11n wireless LAN Standard for 648 block length and 1/2 code rate. The LDPC encoder hardware implementation works at 301.433MHz and it can process 12.12 Gbps throughput. We apply the concept of multiplication by constant matrices in GF(2) due to which hardware required is also optimized. Proposed architecture of QC-LDPC encoder will be compatible for high-speed applications. This hardwired architecture is less complex as it avoids conventionally used block memories and cyclic-shifters.

This paper presents the design of a dual band rectangular Dielectric Resonator Antenna (DRA) coupled to narrow slot aperture that is fed by microstrip line. The fundamental TE 111 mode and higher-order TE 113 mode are excited with their resonant frequencies respectively. These frequencies can be controlled by changing the DRA dimensions. A dielectric resonator with high permittivity is used to miniaturize the global structure. The proposed antenna is designed to have dual band operation suitable for both DCS (1710-1880 MHz) and WLAN (2400-2484 MHz) applications. The return loss, radiation pattern and gain of the proposed antenna are evaluated. Reasonable agreement between simulation and experimental results is obtained.

A compact design of ultra-wideband (UWB) antenna with dual band-notched characteristics based on split-ring resonators (SRR) are investigated in this paper. The wider impedance bandwidth (from 2.73 to 11.34 GHz) is obtained by using two symmetrical slits in the radiating patch and another slit in the partial ground plane. The dual band-notch rejection at WLAN and X-band downlink satellite communication system are obtained by inserting a modified U-strip on the radiating patch at 5.5 GHz and embedding a pair of rectangular SRRs on both sides of the microstrip feed line at 7.5 GHz, respectively. The proposed antenna is simulated and tested using CST MWS high frequency simulator and exhibits the advantages of compact size, simple design and each notched frequency band can be controlled independently by using the SRR geometrical parameters. Therefore, the parametric study is carried out to understand the mutual coupling between the dual band-notched elements. To validate simulation resu...