IEEE 802.11 WLAN

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;

A novel and compact tri-band planar antenna for 2.4/5.2/5.8-GHz wireless local area network (WLAN), 2.3/3.5/5.5-GHz Worldwide Interoperability for Microwave Access (WiMAX) and Bluetooth applications is proposed and studied in this paper. The antenna comprises of a L-shaped element which is coupled with a ground shorted parasitic resonator to generate three resonant modes for tri-band operation. The L-shaped element which is placed on top of the substrate is fed by a 50Ω microstrip feed line and is responsible for the generation of a wide band at 5.5 GHz. The parasitic resonator is placed on the other side of the substrate and is directly connected to the ground plane. The presence of the parasitic resonator gives rise to two additional resonant bands at 2.3 GHz and 3.5 GHz. Thus, together the two elements generate three resonant bands to cover WLAN, WiMAX and Bluetooth bands of operation. A thorough parametric study has been performed on the antenna and it has been found that the three bands can be tuned by varying certain dimensions of the antenna. Hence, the same design can be used for frequencies in adjacent bands as well with minor changes in its dimensions. Important antenna parameters such as return loss, radiation pattern and peak gains in the operating bands have been studied in detail to prove that the proposed design is a promising candidate for the aforementioned wireless technologies.

A MIMO antenna array has been presented in this paper, which has four rectangular microstrip patches as an antenna element(s). An elliptical slot is etched on every radiating patch. The antenna array is simulated in HFSS yielding resonating frequencies of 2.42, 3.49 and 4.98 GHz at S11 <; -10 dB making it applicable for WLANs. RT Duroid 5880 has been used as substrate. The gain ranges from 7 to 11 dB at all resonant frequencies with narrow bandwidth, improving interference rejection characteristics of the proposed antenna. Complete design procedure, comprehensive analysis of mutual coupling among the patches and radiation patterns are also discussed.

Dewasa ini, semakin tingginya permintaan untuk akses layanan komunikasi mobile sehingga pengguna ponsel semakin mengalami peningkatan. Perkembangan teknologi yang semakin cepat menuntut performa terbaik dengan memperhatikan coverage, QoS, implementasi, biaya fitur operasional yang mendukung, dan sebagainya. Dalam jaringan wireless, manajemen mobilitas menyediakan koneksi kepada pengguna mobile ketika mereka bergerak antar subnet yang berbeda berdasarkan kebutuhan layanan mereka. Dengan heterogenitas ini, pengguna akan dapat memilih teknologi akses radio yang menawarkan kualitas yang lebih tinggi, kecepatan data dan mobilitas yang paling cocok untuk aplikasi multimedia yang diperlukan.
Dalam konteks ini, handover vertikal dan interworking antar jaringan akses wireless heterogen merupakan hal penting bagi pengguna jaringan. Para pengguna ponsel ingin lancar dan dinamis roaming diantara jaringan akses yang berbeda untuk menjaga kondisi konektivitas jaringan yang paling optimal. Manajemen handover merupakan salah satu fitur yang paling penting dari manajemen mobilitas.
Dalam simulasi ini, kami mengimplementasikan dan menguji tiga jenis Heterogeneous Wireless Network (HWN), yaitu: WLAN, WiMAX dan UMTS menggunakan OPNET modeler 14,5. Kemudian kita akan mengevaluasi kinerja dari jaringan heterogen dengan beberapa aplikasi, seperti FTP, VoIP dan aplikasi video conference.

Kata Kunci: Heterogeneous Wireless Network, WLAN, WiMAX, UMTS, Manajemen Handover, OPNET

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.

"Internet Protocol Television (IPTV) has gained an enormous growth rate by revolutionizing personal entertainment. High data rates with increased coverage radius of IEEE 802.11n Wireless Local Area Networks (WLANs) motivate the concept of wireless IPTV. Focusing on wireless IPTV, our work deals with the capacity evaluation of IPTV users over IEEE 802.11n. We first present an upper capacity limit for supporting maximum number of users over IEEE 802.11n. We then propose that 4-times packet size is the optimal frame aggregation size for IPTV which maximizes users capacity and QoS. Moreover, we suggest the use of Datagram Congestion Control Protocol (DCCP) at transport layer for IPTV. We show that DCCP increases capacity upto 35% for IPTV by reducing packet losses at Access Point (AP), compared to User Datagram Protocol (UDP). We further evaluate fairness of IPTV traffic in the presence of Transmission Control Protocol (TCP) traffic in the network. Our study concludes that IPTV using DCCP over IEEE 802.11n not only provides increased user’s capacity but also co-exists fairly with TCP traffic. Transmission of combined IPTV and VoIP over a wireless network is a challenging task. We evaluate capacity of combined IPTV and VoIP over IEEE 802.11n. We then evaluate the use of DCCP at transport layer of IPTV. Our study shows that DCCP(TFRC) can provide 25% additional IPTV users. Our results suggest that performance of DCCP is worst in presence of any other UDP flow because of congestion-less mechanism of UDP. Our fairness analysis with TCP traffic shows that IPTV and VoIP using TFRC provide fair share in bandwidth to TCP with 19% increase in combined capacity. We evaluate optimal parameters of IEEE 802.11n AP for running IPTV and VoIP. We show the optimal values and trends of AP parameters including queue size, transmission opportunity, aggregation and block acknowledgement etc. Our study shows that nearly 9 more VoIP users are supported with a queue size of 70 packets and transmission opportunity of 9. Our study concludes that selection of DCCP and optimized parameters over IEEE 802.11n can enhance capacity of IPTV and VoIP by at-least 19% than use of UDP."

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.

O tema deste trabalho, Redes sem fio WLAN em contexto do Jornal O Imparcial, descreve sobre as redes sem fio em ambientes indoor. A abordagem metodológica partiu da revisão bibliográfica sobre o tema, utilizando-se principalmente da tese de mestrado de Marcelo Najnudel, que deu base para uso de metodologias, planejamento e coleta de dados de ambientes indoor, proporcionando melhores resultados para o presente trabalho. Teve como objetivos mostrar definições, conceitos, Softwares utilizados em tarefas específicas de planejamento, a segurança, criptografia e a análise dos resultados levantados das redes sem fio de O Imparcial. Considerando o exposto, o presente estudo discutiu os principais problemas advindo de redes implementadas de forma não planejada, principalmente em locais que se precise de vários pontos de acesso necessitando-se de planejamento de cobertura, canais dentre outros abordados. Por último, considerou-se a necessidade de aplicação de site Survey, no sentido de obter-se informações para melhoramento do ambiente em estudo.

The following is a list of some of IEEE computer science Transactions and Journals that are relevant to our current works at Faculty of Computer Science, Universitas Indonesia
All links to the paper are given in the Journal Names. I also computed the average on each column.
I randomly select 5 most popular and recent papers from each Journal to compute Review Time, Revision Time, and Publication Time in days.
The Detailed Review Time Analysis can be found at the following link.
Open Access Fee for IEEE Journals varied. For hybrid Journals: $1750. For fully open access journals: start from $1350.
I computed Total Impacts per Total Review Time in months. Hope this would be helpful.

Multidimensional constellations are desirable for representing fractional numbers of bits per two dimensions, useful for increasing SNR efficiency, and natural for use with multidimensional coded modulation. Desirable characteristics of such a constellation include good SNR efficiency, low implementation complexit), compatibility with coded modulation and with QAM modems, including small size and peak-to-average power ratio (PAR) of its constituent 2D constellation , phase symmetry, scalability, and capability of supporting an " opportunistic secondary channel. " The gain in SNR efficiency of a multidimensional constellation (lattice code) consisting of the points from a lattice A within a region compared to a cubic constellation is shown to be approximately separable into the coding gain of the lattice A and the " shape gain " of the region , for large constellations. Similarly , the expansion of the associated constituent 2D constellation is shown to be approximately separable into a coding component CER, (A) and a shaping component CER,(l). The N sphere is the region with the best shape gain, but also has large constellation expansion. Bounds for the best possible shape gain versus CER,() or PAR are given. Finally, generalized cross constellations are discussed; these constellations yield a modest shape gain with very low CER,() or PAR, are easily implemented, are well suited for use with coded QAM modems, and can be readily adapted to support a n opportunistic secondary channel.

Low Power Wide Area (LPWA) networks are attracting a lot of attention primarily because of their ability to offer affordable connectivity to the low-power devices distributed over very large geographical areas. In realizing the vision of the Internet of Things (IoT), LPWA technologies complement and sometimes supersede the conventional cellular and short range wireless technologies in performance for various emerging smart city and machine-to-machine (M2M) applications. This review paper presents the design goals and the techniques, which different LPWA technologies exploit to offer wide-area coverage to low-power devices at the expense of low data rates. We survey several emerging LPWA technologies and the standardization activities carried out by different standards development organizations (e.g., IEEE, IETF, 3GPP, ETSI) as well as the industrial consortia built around individual LPWA technologies (e.g., LORa Alliance,WEIGHTLESS-SIG, and DASH7 Alliance). We further note that LPWA technologies adopt similar approaches, thus sharing similar limitations and challenges. This paper expands on these research challenges and identifies potential directions to address them. While the proprietary LPWA technologies are already hitting the market with large nationwide roll-outs, this paper encourages an active engagement of the research community in solving problems that will shape the connectivity of tens of billions of devices in the next decade.

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.

This document details a model structure for a data platform (PaaS) generated to work with sensors belonging to the sensor network of the City of Buenos Aires. The working principle involves the capture, processing and archiving of information generated by devices to extract depth knowledge of the physical world, so that it is possible to take appropriate action based on the interpretation of these data measures.

60 GHz technology offers various advantages over current or existing communications systems. One of the most important is the availability of at least 5 GHz of continuous bandwidth worldwide. While this is comparable to the unlicensed bandwidth allocated for ultra-wideband (UWB) purposes, the 60 GHz bandwidth is continuous and less restricted in terms of power limits. In fact, the large bandwidth at
60 GHz band is one of the largest unlicensed bandwidths being allocated in history.

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In this era of wireless communication there is an integration of more and more radios into a single wireless platform enabling maximum connectivity The multiband antenna approach using PIFA structure enables size reduction, lowers SAR values, augments the bandwidth. These can be obtained by implementing several techniques for the modification of basic structure and use of ground plane. PIFA is also a preferred choice to be incorporated for LTE and WiMAX bands as it inhibits polarization diversity effectively without any decrement in the volume. Single band antenna supports a single frequency of wireless service. And in this era several wireless standards are supported by the equipments. Thus several antennas are employed for each standard leading to a huge space requirement in the handheld devices. Hence the designing of a small PIFA antenna supports multiple bands, small size, improve Gain and good radiation pattern is the prime objective.

A compact, circular UWB fractal antenna with triple reconfigurable notch rejection bands is proposed. It rejects the crowded frequency bands WiMAX, WLAN and X band interferences produced in UWB communication systems. The proposed fractal structure consists of a basic circular patch with circular fractal iterations. By employing this new structure of fractals, the overall size of antenna is reduced 53% to 21x25 mm, in comparison with traditional circular monopole antenna. The implemented antenna operates at 3.1-10 GHz. Re-configurability is realized by designing slots and split ring resonators in desired frequencies with the attached PIN diodes. WLAN band rejection was realized by creating a pair of optimized L-shaped slots in the ground plane. By etching a split ring resonator and a U-shaped slot, X and WiMAX bands were also rejected. Furthermore, by attaching diodes to aforementioned slots and designating the diodes on/off, different bands can be included or rejected. In time domain, the antenna properties are evaluated by a figure of merit called fidelity factor. Finally, the antenna properties are measured in anechoic chamber and the results agrees with simulation findings.

— Network Management Systems have played a great important role in information systems. There are different network management systems such as Remote monitoring, Desktop Sharing, Bandwidth management etc. This paper elaborates the above mentioned issues i.e. remote desktop sharing, Bandwidth Management and Remote monitoring which are accumulated in single network management system. Remote desktop sharing is a technology that allows remote access and remote collaboration on a person's computer. Remote Desktop Sharing provides the capability to technology consultants, administrator or anyone to have full access and control of home computers, office workstations and servers remotely. Another application in network system is Bandwidth management. Bandwidth management is the process of measuring and controlling the communications (traffic, packets) on a network link, to avoid filling the link to capacity or overfilling the link, which would result in network congestion and poor performance of the network. Bandwidth is reserved for each application to ensure the QoS. To ensure the QoS guaranteed services, the SS may reserve more bandwidth than its demand. As a result, the reserved bandwidth may not be fully utilized all the time. In this paper, we propose a scheme, named Bandwidth management, to utilize the unused bandwidth without changing the existing bandwidth reservation. The idea of the proposed scheme is to allow other SSs to utilize the unused bandwidth when it is available. Thus, the system throughput can be improved while maintaining the same QoS guaranteed services. Another important feature of this network management system is Remote desktop monitoring which can be very useful for efficient management of available bandwidth. This paper specially highlights remote monitoring and control refers to the measurement of disparate devices from a network operations center or control room and the ability to change the operation of these devices from that central office. Remote monitoring allows monitoring operations of one computer through other computer in network. this can be done using TCP/IP protocol. Using this feature server can shutdown client's PC. If server finds out that any client is misusing bandwidth he may warn him by sending alert message if client continues misuse of bandwidth he may shutdown his Computer. This paper intends to increase network management functions by making system capable of utilizing available bandwidth efficiently with help of Remote monitoring functionalities. Bandwidth management feature relies on user-defined bandwidth classes and policy rules to manage the available bandwidth; this avoids wastage of precious available bandwidth. If a user uses this system user can simultaneously monitor client's desktop, share desktop and dynamically handle available bandwidth as per the requirement of client. This system uses Wi-Fi (WLAN) to connect computers in network. This paper is to implement the client/server network management system using Wi-Fi. And then this paper intends to show data or message structure of client/server and how to work using TCP/IP protocol.

Computer networks have grown rapidly in term of size and complexity, leading to have a critical point especially from the perspective of computer architecture, which not only have been in usage but also have applied to businesses and governments. Wireless networking applications have recently spread in many aspects of life where users are in need to use them without being restricted at a specific location. Furthermore, because of that complexity, wireless networks were been the appropriate way to respond to that technical. Wireless networks have developed quickly, becoming the best choice in many cases due to cheap prices of wireless solutions in comparison with wired networks. WLANs are more vulnerable to security threats and attacks because of its open transport medium. Thus, the need for security protocols is for immunize wireless networks against those threats, as lots of hackers are widespread on those networks. In addition to that, there is a need to improve those protocols to increase protection of networks in general. On the other hand, additional bytes resulting from those protocols have formed additional burden on network performance. As wireless LAN architecture is basically relied on a client-server model, we have checked and evaluated in this research the impact of security protocols on WLAN performance, which helps us to choose the best protocol to improve users access to the shared resources which are at remote server network. The impact of these protocols on network performance has been evaluated by adding those Protocols to open source GloMoSim environment, this can be applied through three cases: "low density network status", "high density network status" and "real network status". And recent simulation results show that the performance of these protocols are varies according to the environment applied within them, noting that there is no effective Protocol in all environments, i.e. the suitable Protocol in an environment may be unsuitable in other ones. After comparing performance results in simulations with performance results in the real network, we can see that the best performance protocol is WEP followed by WPA2 and WPA. Also, The best protocol for both performance and security is the WPA2 followed by the WPA protocol and the WEP protocol. Hence, our choice to one of the security protocols depends on what we want to secure in the level of protection and the performance of the network.

Wireless LAN technologies implemented on controller-based wireless LAN design not to mention their critical evaluation is an issue which causes a great deal of debate. Entering into a new era that the needs of technology optimization grow rapidly, Enterprise wireless networking is meaningful to be achieved not to mention that it is considered a basic topic to be analyzed. This research is particularly outstanding for the reader because it will analyze the most important standards and protocols of wireless technology, distinctly 802.11 network tailored  o business needs. It must be stressed that the wireless LAN controller-based WLAN design, and autonomous AP based wireless LAN design will be compared and contrasted. Furthermore, there will be critically evaluated related technologies including WLAN controller, CAPWAP and DTLS, user authentication - EAP and EAP methods not to mention 802.11n and 802.11ac. All the above, will be adopted and implemented on a medium company with 265 employees. There will also be provided floor plans for the two buildings and two floors that the company owes not to mention a logical diagram where all will be connected wirelessly based on national and international communication standards. Considering the factors related to this topic, the question of what specific consequences arise when addressing this theme must be elaborated.

The  next  generation  of  wireless  local  area  networks (WLANs),  currently  standardized  within  IEEE  S02.11ac,  will
surely  adopt  multiuser  multiple-input  multiple-output  (MU­
MIMO)  technology.  This  paper  addresses  the  design  of  a  mul­
tiuser  proportional  fair  scheduling  scheme,  based  on  MU-MIMO orthogonal  frequency  division  multiplexing  (OFDM),  that  is  able to  schedule  simultaneous  transmissions  to  various  users  while providing  a  high  degree  of  fairness.  The  proposed  scheme  is complemented  by  a  fast  link  adaptation  (FLA)  strategy  that,  in light  of  the available channel  state information  (CSI), determines the  most  appropriate  transmission  parameters  for  each  selected user.  Simulation  results  generated  using  specifi cations  envisaged for  IEEE  S02.11ac demonstrate the gains off ered by  the proposed
technique  with  practical  modulation  and  coding  schemes.

The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.

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.

The current communication requirements are moving quickly to mobile ad-hoc networks, mainly because of the decreasing cost of wireless networking technology and the increasing capacity to integrate into embedded devices technologies such as WiFi, ZigBee, Bluetooth, and WAVE. It is important to understand the limitation or the strength of each protocol and standard in order to make a better selection decision at the moment of implementing a specific scenario. This paper evaluates how routing protocols perform in mobile scenarios when the speed of nodes is relatively high. Our research shows that reactive routing protocols have a better packet delivery ratio (PDR) than proactive routing protocols. However, proactive routing protocols have a smaller end-to-end delay and hops count.

An E-shaped printed monopole antenna with loaded resonant elements suitable for penta-band multi-input multi-output (MIMO) application is proposed. The simple E-shaped monopole antenna results in a single resonance, and by loading the vertical arm of the antenna with narrow slots and stubs, a multi-band antenna can be obtained. The slots so placed on the antenna create L-shaped resonance paths which are multiples of λ g /4, and stubs resonate at λ g /4. The antenna is designed for operation over the UMTS, WiMAX and WLAN frequencies 2.1, 2.5, 3.5, 5.2, 5.8 GHz. A two element array of such antennas with close spacing of λ g /15 is suitable for MIMO application. The array has low mutual coupling, low envelope correlation, high efficiency and good radiation patterns over all five frequency bands. Simulation and measurement results are compared and discussed.

Now a day’s WLANs (Wireless Local Area Networks) have been mostly used in offices, colleges and public areas. This network may or may not be secure for secrete data transfer. The newly adopted 802.11e protocol gives many QoS in WLANs. However there are some lacks of security in it. In this looking on the 802.11e protocol for QoS provide in WLANs and two new covert channels are proposed. These new covert channel methods use signaling technique to provide suitable communication. This type of covert channels have no effect on traffic, thus it may not be detected by continuously monitoring on traffic

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.

 Abstract— Wireless local area networks (LANs) are playing a major role in the information technology revolution. They have found their way into a wide variety of markets including financial sectors, corporations, health care, and education.The rapid deployment of wireless LANs is testimony to the inherent benefits of this technology. Unfortunately, most wireless deployments are, at this time, fundamentally insecure. This is not an exaggeration. It is an accurate assessment of the reality of the current state of the security of wireless 802.11-based environments.Because of its transmission characteristic, many security problems have set in. This paper aims to introduce the security mechanism of the wireless LAN and points out the shortcoming of it. Index Terms—About four key words or phrases in alphabetical order, separated by commas.

In this paper, a compact multiband Planar Inverted-F Antenna (PIFA) having two open ended slots on the ground plane is proposed. The ground plane also acts as a radiator element, the overall volume of PIFA can be reduced significantly, which further reduces thickness of the handheld devices such as mobile phones. The antenna operates at multiple bands i.e. GPS, GLONASS, DCS, PCS, UMTS, WLAN/Bluetooth, 4G LTE & HYPERLAN/2. The performance parameters of the proposed antenna are satisfying the requirements of advance wireless communication devices which can be observed from the simulation results The measured results are also presented and discussed. Both simulated and measured results are in good match.

"O trabalho desenvolvido ao longo desta dissertação consistiu no desenho, montagem e teste de um sistema de baixo custo capaz de fazer telemetria a longas distâncias.

Este sistema tem como principal objectivo ser aplicado nos exercícios de afundamento de navios desmilitarizados utilizando mísseis do tipo Seasparrow, procurando assim medir parâmetros físicos (temperatura, pressão e movimentação em torno dos três eixos axiais) durante o seu impacto.

Esta medição deve ser feita de uma distância segura (entre 3 e 8 milhas náuticas).

Para responder a tal necessidade procurou-se desenvolver um sistema off-the-shelf, com baixo custo que cumprisse as exigências do cenário em estudo.

Para possibilitar o envio a longa distância – navio alvo e navio de monitorização – foi utilizado o protocolo IEEE 802.11g. A restante rede de sensores implementava o protocolo IEEE 802.3.

O sistema desenvolvido foi sujeito a inúmeros testes, procurando assim determinar se este se adequava ao carácter sui generis do cenário em causa."