Wireless LAN Card Research Articles

Hardware Implementation of Intrusion Detection System for Ad-Hoc Network

<p>New technologies have been developed in wireless adhoc network need more security. To widespread the adhoc networks we turn in the attention of wireless hand held device mobile phones communicate with short distance using wireless lan card or Bluetooth. The performance of mobile phone are improved greatly for last few years .so security is more important for mobile networks In this paper hardware implementation of single hop ad-hoc network is implemented and analysed using microcontroller. The protocol implemented in this paper is primarily based on, Ad hoc On-Demand Distance Vector routing. We adopt On Demand Distance Vector routing solely based on source routing and “On Demand” process, so each packet does not have to transmit any periodic routing information. We implemented intrusion detection system with five different nodes and the performance parameters like packet delivery ratio, throughput, delay are computed with attacker and without attacker and on demand distance vector routing protocols is proposed to implement in hardware using Zigbee</p>

IVs to Skip for Immunizing WEP against FMS Attack

The WEP (Wired Equivalent Privacy) is a part of IEEE 802.11 standard designed for protecting over-the-air communication. While almost all of the WLAN (Wireless LAN) cards and the APs (Access Points) support WEP, a serious key recovery attack (aka FMS attack) was identified by Fluhrer et al. The FMS attack can basically be prevented by skipping IVs (Initial Values) used in the attack, but naive skip methods reveal information on the WEP key since most of them depend on the WEP key and the patterns of the skipped IV reveal it. In order to skip IVs safely, the skip patterns must be chosen carefully. In this paper, we review the attack conditions (6) and (7), whose success probability is the highest, 0.05, amongst all known conditions to guess one key-byte from one packet. Then we identify their safe skip patterns.

A novel miniaturized triband PIFA for MIMO applications

AbstractMultiband antennas are vital in meeting the modern telecommunication demands of mobile terminals. Using the spatial properties of multipath channels, multiple‐input multiple‐output (MIMO) communication systems employ antenna arrays to increase their communication capacity. This article presents a novel printed inverted “F” antenna (PIFA), which has been used to design a miniaturized triband antenna. In turn, the triband antenna has been used as an element in various arrays of MIMO applications. Specifically, the antenna element has been constructed and applied, in arrays of two and four, in a laptop PCMCIA wireless LAN card. The size of the four element MIMO antenna array is 50 mm × 13 mm × 8 mm, which translates to 0.4λ × 0.1λ × 0.06λ at 2.45 GHz. The input impedance of the single element antenna has been measured at UCLA. The antenna has a return loss lower than −10 dB within the 2.4–2.5 GHz, 5.15–5.35 GHz, and 5.7–5.85 GHz bands. The measured scattering matrices of two and four element arrays have been used to calculate the total active reflection coefficient (TARC). TARC has been calculated for different combinations of excitation signals applied at each port. Each excitation signal has a unity magnitude and a random phase, thus leading to innumerable signal combinations. Our results reveal that “off” diagonal elements of the scattering matrix (couplings between elements) are as important as diagonal elements in calculating the TARC and the radiation efficiency of arrays. Furthermore, increasing the number of elements in a MIMO system with a limited volume will increase the channel capacity but lower the radiation efficiency. The experimental and simulation results have been in agreement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 724–731, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22239

Key-Dependent Weak IVs and Weak Keys in WEP -- How to Trace Conditions Back to Their Patterns --

The WEP (Wired Equivalent Privacy) is a part of IEEE 802.11 standard designed for protecting over the air communication. While almost all of the WLAN (Wireless LAN) cards and the APs (Access Points) support WEP, a serious key recovery attack (aka FMS attack) was identified by Fluhrer et al. The attack was then extended and implemented as WEP cracking tools. The key recovery attacks can basically be prevented by skipping certain IVs (Initial Values) called weak IVs, but the problem is that there exist huge amount of key-dependent weak IVs and the patterns of them have not been fully identified yet. The difficult part is that a naive approach to identify the key-dependent weak IVs requires the exhaustive search of IVs and WEP keys, and hence is infeasible. On the other hand, it might be feasible to skip the key-dependent weak IVs for the currently set WEP key but this reveals information on the WEP key from the skipped patterns. To skip them safely, the patterns of the key-dependent weak IVs must be identified in the first place. In this paper, we analyze the famous condition for IVs and WEP keys to be weak in the FMS attack, i.e. 0 ≤ S[1] ≤ t' <t and S[1] + S[S[1]] = t (cf. Sect. 2.3 for more details), and then trace it back to the patterns of IVs and WEP keys theoretically. Once such patterns are obtained, their safe skip patterns can be obtained by using them.

End-to-end QoS provisioning in 4G with mobile hotspots

The novel concept of mobile hotspots, characterized by a group of wireless users equipped with wireless LAN cards, moving as a whole and requiring Internet connectivity, is gaining the interest of the telecommunications research community. This article intends to contribute to this research topic by proposing alternative solutions for the deployment of a mobile gateway device offering 3G connectivity to the group of WLAN users while they are moving. This is a decisive aspect of the 3G migration to 4G networks. The proposed solutions allow for two-hop wireless paths between WLAN and 3G systems, and performing control over-high layer issues, specifically focusing on end-to-end QoS provisioning. The pros and cons of envisaged design solutions are addressed and their relevance justified considering purposes, target users, and applications.

Development of a remote impact damage identification system

In this paper, an impact damage identification approach is proposed. Based on this approach, a remote impact damage identification system has been developed. The remote identification system consists of hardware and software. The hardware consists of a carbon-fiber-reinforced plastic (CFRP) plate with four surface-mounted piezoelectric sensors, a digital oscilloscope, a local network, a wireless LAN card, and a notebook computer. The software includes a source location algorithm based on fast wavelet transform and an impact load identification algorithm based on impact response inverse analysis. The piezoelectric sensors can detect Lamb wave signals generated by impact load without any amplification. The source location algorithm can reduce the influence of noise in the Lamb wave signals. When the CFRP plate is impacted, the oscilloscope promptly records the impact response signals detected by the mounted piezoelectric sensors, and the computer simultaneously receives the signals via the local network and wireless LAN card from the oscilloscope. The system can remotely identify the impact position and the impact load history with good precision in real time. Copyright © 2005 John Wiley & Sons, Ltd.

A Two-Tier Heterogeneous Mobile Ad Hoc Network Architecture and Its Load-Balance Routing Problem

The mobile ad hoc network (MANET) has attracted a lot of interest recently. However, most of the existing works have assumed a stand-alone MANET. In this paper, we propose a two-tier, heterogeneous MANET architecture which can support Internet access. The low tier of the network consists of a set of mobile hosts each equipped with a IEEE 802.11 wireless LAN card. In order to connect to the Internet and handle the network partitioning problem, we propose that the high tier is comprised of a subset of the mobile hosts, called gateways, which can access to cellular/infrastructure networks. The high tier is heterogeneous in the sense that the network interfaces in the gateway hosts could be IEEE 802.11 cards, PHS handsets, or GPRS handsets characterized by different bandwidths and latencies. Observing that the gateways could become the bottlenecks of the two-tier network, we propose a set of solutions, namely boundary-moving, host-partitioning, and probabilistic solutions, to solve the load-balance routing issue. Implementation issues/concerns of these schemes are discussed. Simulation results are presented to compare these load-balance routing schemes.

Virtual operator based AAA in wireless LAN hot spots with ad-hoc networking support

Sound and effective authentication, authorization and accounting (AAA) schemes for convenient and secure mobile wireless accesses are of great importance given the increased popularity and business opportunities in public wireless LAN hot spots. One possible scheme, which uses the mobile users' service providers as the single point of contact for all AAA transactions, is emerging as a very promising solution. We refer to such service providers as "virtual operators". In this paper, we discuss various existing virtual operator AAA solutions and present our solution that is entirely based on IP. By converging both the AAA process and data transmission at the IP layer, our solution is extremely flexible and extensible. Compared with existing solutions, it works across multiple air interfaces and is interoperable with wireless LAN cards from different vendors. Further, it supports the scenario where access points use intermediate mobile terminals and ad-hoc networking to extend their service coverage. Service credits can be properly assigned to these intermediate terminals as incentives for providing relay services. Our solution is especially useful for a public access LAN environment where multiple wireless access technologies, a diverse set of wireless products and different types of wireless operators may coexist to provide mobile users with convenient and comprehensive wireless access solutions.

An S-Band Reflection-Type Phase Shifter - A Design Example Using Ferroelectrics

AbstractOne of the challenges faced in using ferroelectrics in high frequency devices is how to effectively use the material in a circuit design. A compact reflection-type phase shifter fabricated on sapphire substrates coated with ferroelectric barium strontium titanate (BST) thin-films has been built which shows the promise of using BST thin films in the design of tunable microwave devices. The phase shifter, fabricated as one monolithic assembly, consists of a 3dB coupler, meandered line inductors and tunable interdigital capacitors. A continuously variable phase shift range of more than 100° using the branch-line coupler was obtained at a center frequency of 2.95 GHz, and more than 90° phase shift over 200 MHz bandwidth with a bias voltage range from 0 V to 175 V. The phase shifter using the Lange coupler has over 700 MHz bandwidth centered at 2.2 GHz with a phase shift of more than 90° and an insertion loss less than 2 dB and return loss of greater than 14 dB, over a bias voltage range from 0 V to 160 V. The loss of the BST phase shifter presented in this work is on the order of other commercially available RF front-end components, such as bandpass filters and RF switches. This holds promise for the practical realization of smart antenna systems in cellular handsets and wireless LAN cards.

Planning system for indoor wireless network

A novel wireless LAN prediction tool using the genetic algorithm and neural network has been proposed. We establish a site survey tool system to predict the received signal strength index (RSSI) in an indoor environment. The system includes six items. (1) The fading function: it corrects the functional characteristics of the RSSI for different types of wireless LAN cards in free space. (2) The setting of the attributes of obstacles in the indoor environment: the idea of a "single attribute of local area" is proposed. If there are the same obstacles in one area, we set the area as one attribute. (3) The genetic algorithm: where we use reproduction, crossover and mutation to obtain the propagation loss through the different obstacles (Li). (4) The neural network: we use neural network concept to correct the prediction error arising from the multipath effect in the indoor environment. (5) The auxiliary judgment for the sampling points: the method is helpful to users in establishing the best sampling points. (6) The calibration of prediction results: we use calibration to correct the prediction error arisen from Li.

Rapid implementation of the MAC and interface circuits for the wireless LAN cards using FPGA

This paper studies the rapid design and implementation of the medium access control (MAC) and related interface circuits for 802.11 wireless LANs based on the field programmed gate array (FPGA) technology. Our design is thus aimed to support both the distributed coordination function (DCF) and the point coordination function (PCF) with the aid of FPGA technology. Furthermore, in an infrastructure network, some stations may serve as the access points (APs) which may function like a learning bridge. This paper will also discuss how to design for such application. The hardware of the MAC and interface may at least consist of three major parts: wireless transmission and reception processes and interface, host (bus) interface, and the interface to the distributed system (optional). Through the increasing popularity of FPGA design, this paper presents how Complex Programmable Logic Devices (CPLD) can be utilized for speedy design of prototypes. It also demonstrates that there is much room for low-cost hardware prototype design to accelerate the processing speed of the MAC control function and for field testing.