Dependability in wireless networks: can we rely on WiFi?

WiFi - short for "wireless fidelity" - is the commercial name for the 802.11 products that have flooded the corporate wireless local area network (WLAN) market and are becoming rapidly ingrained in our daily lives via public hotspots and digital home networks. Authentication and confidentiality are crucial issues for corporate WiFi use, but privacy and availability tend to dominate pervasive usage. However, because a technology's dependability requirements are proportional to its pervasiveness, newer applications mandate a deeper understanding of how much we can rely on WiFi and its security promises. In this article, we present an overview of WiFi vulnerabilities and investigate their proximate and ultimate origins. The intended goal is to provide a foundation to discuss WiFi dependability and its impact on current and future usage scenarios. Although a wireless network's overall security depends on the network stack to the application layer, this article focuses on specific vulnerabilities at the physical (PHY) and data (MAC) layers of 802.11 network

SECURITY OF INFRASTRUCTURE MODE OF IEEE 802.11 WIRELESS NETWORK STANDARD

Bežične mreže sve se češće koriste i danas su postale standard u povezivanju računala nudeći pritom jednostavnu implementaciju uz smanjene troškove, zadovoljavajuće brzine mrežne propusnosti (eng. Bandwith) te veću mobilnost korisnika. Bežična komunikacija korisniku daje veću mobilnost, a samim time brži i lakši pristup izvoru informacija. Kada se govori o bežičnim lokalnim mrežama, kao posebno se važno nameće pitanje sigurnosti. Također, bežične mreže predstavljaju najnesigurniji dio u lokalnoj žičanoj mreži (LAN) zato što im je medij - nosioc zrak, čime mreža postaje dostupna i izvan organizacije u kojoj se koristi. Sigurnosni algoritmi (enkripcije) sprečavaju mogućnost neovlaštenog korištenja mreže, ali ne nude potpunu sigurnost. Ovaj rad dat će pregled sigurnosnih tehnologija infrastrukturnog načina rada bežične mreže (eng. wlan) i dati preporuke sigurnijeg načina rada. Rad nudi pregled metoda infrastrukturne sigurnosti wlan standarda IEEE 802.11.Wireless networks are increasingly used today and have become the de facto standard for connecting computers while at the same time offering simple implementation with reduced costs, satisfactory bandwidth speeds and greater mobility of users. Wireless communication provides users with greater mobility, and therefore faster and easier access to sources of information. When talking about wireless local area networks, a particularly important issue is that of security. Wireless networks are the least secure part of the wired local area network (LAN) because they use air as the medium for transmission, and in so doing the network becomes available outside the organization in which it is used. Security algorithms (encryption) prevent the possibility of unauthorized use of the network, but they do not offer one hundred percent security. This paper will present an overview of security technologies regarding infrastructure mode of wireless network and make recommendations for secure mode. The paper provides an overview of the methods of infrastructure security with regard to the IEEE 802.11 WLAN standard

A study of QoS support for real time multimedia communication over IEEE802.11 WLAN : a thesis presented in partial fulfillment of the requirements for the degree of Master of Engineering in Computer Systems Engineering, Massey University, Albany, New Zealand

Quality of Service (QoS) is becoming a key problem for Real Time (RT) traffic transmitted over Wireless Local Area Network (WLAN). In this project the recent proposals for enhanced QoS performance for RT multimedia is evaluated and analyzed. Two simulation models for EDCF and HCF protocols are explored using OPNET and NS-2 simulation packages respectively. From the results of the simulation, we have studied the limitations of the 802.1 le standard for RT multimedia communication and analysed the reasons of the limitations happened and proposed the solutions for improvement. Since RT multimedia communication encompasses time-sensitive traffic, the measure of quality of service generally is minimal delay (latency) and delay variation (jitter). 802.11 WLAN standard focuses on the PHY layer and the MAC layer. The transmitted data rate on PHY layer are increased on standards 802.1 lb, a, g, j, n by different code mapping technologies while 802.1 le is developed specially for the QoS performance of RT-traffics at the MAC layer. Enhancing the MAC layer protocols are the significant topic for guaranteeing the QoS performance of RT-traffics. The original MAC protocols of 802.11 are DCF (Distributed Coordination Function) and PCF (Point Coordinator Function). They cannot achieve the required QoS performance for the RT-traffic transmission. IEEE802.lle draft has developed EDCF and HCF instead. Simulation results of EDCF and HCF models that we explored by OPNET and NS-2, show that minimal latency and jitter can be achieved. However, the limitations of EDCF and HCF are identified from the simulation results. EDCF is not stable under the high network loading. The channel utilization is low by both protocols. Furthermore, the fairness index is very poor by the HCF. It means the low priority traffic should starve in the WLAN network. All these limitations are due to the priority mechanism of the protocols. We propose a future work to develop dynamic self-adaptive 802.11c protocol as practical research directions. Because of the uncertainly in the EDCF in the heavy loading, we can add some parameters to the traffic loading and channel condition efficiently. We provide indications for adding some parameters to increase the EDCF performance and channel utilization. Because all the limitations are due to the priority mechanism, the other direction is doing away with the priority rule for reasonable bandwidth allocation. We have established that the channel utilization can be increased and collision time can be reduced for RT-traffics over the EDCF protocol. These parameters can include loading rate, collision rate and total throughput saturation. Further simulation should look for optimum values for the parameters. Because of the huge polling-induced overheads, HCF has the unsatisfied tradeoff. This leads to poor fairness and poor throughput. By developing enhanced HCF it may be possible to enhance the RI polling interval and TXOP allocation mechanism to get better fairness index and channel utilization. From the simulation, we noticed that the traffics deployment could affect the total QoS performance, an indication to explore whether the classification of traffics deployments to different categories is a good idea. With different load-based traffic categories, QoS may be enhanced by appropriate bandwidth allocation Strategy

Safetynet version 2, a packet error recovery architecture for vertical handoffs

Mobile devices are connecting to the Internet through an increasingly heterogeneous network environment. This connectivity via multiple types of wireless networks allows the mobile devices to take advantage of the high speed and the low cost of wireless local area networks and the large coverage of wireless wide area networks. To maximize the benefits from these complementing characteristics, the mobile devices need to be able to switch seamlessly between the different network types. However, the switch between the technologies, also known as a vertical handoff, often results in significant packet loss and degradation of connectivity due to handoff delay and also increased packet loss rate on the border of the coverage area of the networks. In our previous work, we have proposed an inter technology mobility management architecture which addresses the packet losses using selective resending of packets lost during the handoff period. In this paper, we extend the architecture to address packet losses due to wireless errors more efficiently by taking advantage of erasure codes to form redundancy packets. We propose to send these redundancy packets over both links. We show that this proposal reduces both the chances of packet loss and the buffering requirements of the original Safetynet scheme

Millimeter-wave Wireless LAN and its Extension toward 5G Heterogeneous Networks

Millimeter-wave (mmw) frequency bands, especially 60 GHz unlicensed band, are considered as a promising solution for gigabit short range wireless communication systems. IEEE standard 802.11ad, also known as WiGig, is standardized for the usage of the 60 GHz unlicensed band for wireless local area networks (WLANs). By using this mmw WLAN, multi-Gbps rate can be achieved to support bandwidth-intensive multimedia applications. Exhaustive search along with beamforming (BF) is usually used to overcome 60 GHz channel propagation loss and accomplish data transmissions in such mmw WLANs. Because of its short range transmission with a high susceptibility to path blocking, multiple number of mmw access points (APs) should be used to fully cover a typical target environment for future high capacity multi-Gbps WLANs. Therefore, coordination among mmw APs is highly needed to overcome packet collisions resulting from un-coordinated exhaustive search BF and to increase the total capacity of mmw WLANs. In this paper, we firstly give the current status of mmw WLANs with our developed WiGig AP prototype. Then, we highlight the great need for coordinated transmissions among mmw APs as a key enabler for future high capacity mmw WLANs. Two different types of coordinated mmw WLAN architecture are introduced. One is the distributed antenna type architecture to realize centralized coordination, while the other is an autonomous coordination with the assistance of legacy Wi-Fi signaling. Moreover, two heterogeneous network (HetNet) architectures are also introduced to efficiently extend the coordinated mmw WLANs to be used for future 5th Generation (5G) cellular networks.Comment: 18 pages, 24 figures, accepted, invited paper

An innovative mobile application for construction programme managers

Construction programme management is a complex and information-intensive environment. The construction programme management team requires access to construction information in real-time and when needed. The current increasing use of mobile devices offers an opportunity to meet this need. The efficient management of construction programmes is one of the major factors for improving stakeholders’ satisfaction. An innovative tool is needed in accessing the right information at the right time, especially when spontaneous and urgent decision-making is needed. To this end, the innovative use of a mobile device in delivering information and services to the management team in real-time and based on their current context offers significant benefits. This paper discusses context-aware computing, the enabling technologies for geolocation and the development of a prototype, mobile, context-aware application for construction programme management. The prototype system developed is based on the findings from an earlier study of user requirements which showed that the ability to provide relevant information and services at an appropriate time and at the most appropriate location has the potential to improve the monitoring and control of construction programmes. The prototype system demonstrates the provision of context-specific information and services to construction programme managers using a mobile device. The benefits and limitations of the proposed approach are discussed and conclusions drawn about the potential impact of enhanced information delivery for the efficiency of the construction programme managers