Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

Cooperative & cost-effective network selection: a novel approach to support location-dependent & context-aware service migration in VANETs

Vehicular networking has gained considerable interest within the research community and industry. This class of mobile ad hoc network expects to play a vital role in the design and deployment of intelligent transportation systems. The research community expects to launch several innovative applications over Vehicular Ad hoc Networks (VANETs). The automotive industry is supporting the notion of pervasive connectivity by agreeing to equip vehicles with devices required for vehicular ad hoc networking. Equipped with these devices, mobile nodes in VANETs are capable of hosting many types of applications as services for other nodes in the network. These applications or services are classified as safety-critical (failure or unavailability of which may lead to a life threat) and non-safety-critical (failure of which do not lead to a life threat). Safety-critical and non-safety-critical applications need to be supported concurrently within VANETs. This research covers non-safety-critical applications since the research community has overlooked this class of applications. More specifically, this research focuses on VANETs services that are location-dependent. Due to high speed mobility, VANETs are prone to intermittent network connectivity. It is therefore envisioned that location-dependence and intermittent network connectivity are the two major challenges for VANETs to host and operate non-safety-critical VANETs services. The challenges are further exacerbated when the area where the services are to be deployed is unplanned i.e. lacks communication infrastructure and planning. Unplanned areas show irregular vehicular traffic on the road. Either network traffic flows produced by irregular vehicular traffic may lead to VANETs communication channel congestion, or it may leave the communication channel under-utilized. In both cases, this leads to communication bottlenecks within VANETs. This dissertation investigates the shortcomings of location-dependence, intermittent network connectivity and irregular network traffic flows and addresses them by exploiting location-dependent service migration over an integrated network in an efficient and cost-effective manner

Evaluating IP security and mobility on lightweight hardware

This work presents an empirical evaluation of applicability of selected existing IP security and mobility mechanisms to lightweight mobile devices and network components with limited resources and capabilities. In particular, we consider the Host Identity Protocol (HIP), recently specified by the IETF for achieving authentication, secure mobility and multihoming, data protection and prevention of several types of attacks. HIP uses the Diffie-Hellman protocol to establish a shared secret for two hosts, digital signatures to provide integrity of control plane and IPsec ESP encryption to protect user data. These computationally expensive operations might easily stress CPU, memory and battery resources of a lightweight client, as well as negatively affect data throughput and latency.We describe our porting experience with HIP on an embedded Linux PDA, a Symbian-based smartphone and two OpenWrt Wi-Fi access routers, thereby contributing to the protocol deployment. We present a set of measurement results of different HIP operations on these devices and evaluate the impact of public-key cryptography on the processor load, memory usage and battery lifetime, as well as the influence of the IPsec encryption on Round-Trip Time and TCP throughput. In addition, we assess how the lightweight hardware of a mobile handheld or a Wi-Fi access router in turn affects the duration of certain protocol operations including HIP base exchange, HIP mobility update, puzzle solving procedure and generation of an asymmetric key pair. After analyzing the empirical results we make conclusions and recommendations on applicability of unmodified HIP and IPsec to resource-constrained mobile devices. We also survey related work and draw parallels with our own research results

Evaluating IP security on lightweight hardware

TCP/IP communications stack is being increasingly used to interconnect mobile phones, PDAs, sensor motes and other wireless embedded devices. Although the core functionality of communications protocols has been successfully adopted to lightweight hardware from the traditional Internet and desktop computers, suitability of strong security mechanisms on such devices remains questionable. Insufficient processor, memory and battery resources, as well as constraints of wireless communications limit the applicability of many existing security protocols that involve computationally intensive operations. Varying capabilities of devices and application scenarios with different security and operational requirements complicate the situation further and call for agile and flexible security systems. This study does an empirical evaluation of applicability of selected existing IP security mechanisms to lightweight (resource-constrained) devices. In particular, we evaluate various components of the Host Identity Protocol (HIP), standardized by the Internet Engineering Task Force for achieving authentication, shared key negotiation, secure mobility and multihoming and, if used with IPsec, integrity and confidentiality of user data. Involving a set of cryptographic operations, HIP might easily stress a lightweight client, while affecting performance of applications running on it and shortening battery lifetime of the device. We present a background and related work on network-layer security, as well as a set of measurement results of various security components obtained on devices representing lightweight hardware: embedded Linux PDAs, Symbian-based smartphones, OpenWrt Wi-Fi access routers and wireless sensor platforms. To improve computational and energy efficiency of HIP, we evaluate several lightweight mechanisms that can substitute standard protocol components and provide a good trade-off between security and performance in particular application scenarios. We describe cases where existing HIP security mechanisms (i) can be used unmodified and (ii) should be tailored or replaced to suit resource-constrained environments. The combination of presented security components and empirical results on their applicability can serve as a reference framework for building adaptable and flexible security services for future lightweight communication systems

Performance analysis for wireless G (IEEE 802.11G) and wireless N (IEEE 802.11N) in outdoor environment

This paper described an analysis the different capabilities and limitation of both IEEE technologies that has been utilized for data transmission directed to mobile device. In this work, we have compared an IEEE 802.11/g/n outdoor environment to know what technology is better. The comparison consider on coverage area (mobility), throughput and measuring the interferences. The work presented here is to help the researchers to select the best technology depending of their deploying case, and investigate the best variant for outdoor. The tool used is Iperf software which is to measure the data transmission performance of IEEE 802.11n and IEEE 802.11g

Performance Analysis For Wireless G (IEEE 802.11 G) And Wireless N (IEEE 802.11 N) In Outdoor Environment

This paper described an analysis the different capabilities and limitation of both IEEE technologies that has been utilized for data transmission directed to mobile device. In this work, we have compared an IEEE 802.11/g/n outdoor environment to know what technology is better. the comparison consider on coverage area (mobility), through put and measuring the interferences. The work presented here is to help the researchers to select the best technology depending of their deploying case, and investigate the best variant for outdoor. The tool used is Iperf software which is to measure the data transmission performance of IEEE 802.11n and IEEE 802.11g