Wireless mesh networks have increasingly become an object of interest in recent years as a strong alternative to purely wired infrastructure networks and purely mobile wireless networks. Given the challenges that have arisen in construction, deployment and maintenance of wireless mesh networks, we outline a broad experimental research program in the area of medium-to-large scale community wireless networks. Our research is conducted in the context of an operational community network built in our test bed laboratory with continual plans to expand to the town of Troy, NY (up to hundreds of nodes in a 1-2 mile radius around RPl campus). Leveraging Global Positioning System (GPS) receivers and Geographic Distributed Addressing (GDA), a novel and intuitive addressing assignment, geographic-based forwarding algorithms such as GPSR and TBF can be easily tested and traffic engineering theories implemented in a real-world environment. Our paper documents several design considerations and contributions in implementing community wireless networks including autoconfiguration, addressing structure and antenna characteristics among other items, in addition to describing our novel test bed lab where RF effects of distances of thousands of meters can be simulated with server, antenna and variable attenuator clusters.

In this paper we present our work towards deploying a community wireless network with ad hoc communication and routing between its elements. We describe our network model and implementation of wireless routers, while motivating decisions and pointing out open issues. The main advantage of our approach is the low deployment cost and inherent flexibility in terms of adapting the network configuration with little or no human intervention, which in turn can be exploited to support the dynamic addition, removal and mobility of network elements.

Wireless mobile ad hoc network experimentation is subjected to stochastic factors from the radio environment and node mobility. To achieve test repeatability and result re-producibility such stochastic factors need to be controlled or assessed in order to obtain conclusive results. This has implications on the design of testbeds. We present a methodology that addresses repeatability and describe how it has guided us in the design of our Ad hoc Protocol Evaluation (APE) testbed. Finally, by using APE, we present side-by-side routing protocol comparison results and show a radio phenomena that is not visible in simulations.

UMTS 3G networks are going to be widely deployed commercially, even if in their first releases they will be mainly focused on telephony and multimedia services based on circuit switched technologies. The roll out of the 3GPP IP Multimedia Subsystem (IMS), that can be forecast to happen in the next few years, will introduce mobile users to a new class of multimedia services based on the Internet protocol. The research community is already investigating a possible evolution for the 3G networks based on heterogeneous high-speed access networks allowing new multimedia services and a global coverage (Beyond 3G - B3G). In the present paper we describe a testbed developed by the Co.Ri.TeL. Consortium in the framework of the Presto Project, whose objective is to provide a suitable and common platform, inspired to the IMS ideas, for experimenting a wide variety of B3G SIP-based mobile services. The services experimented on top of the testbed include a multiuser video conferencing architecture, added-value user-defined multimedia services, an audio-video message box and a video-on-demand provisioning infrastructure. The service provisioning mechanisms are all built within a common mobility-management and security framework, providing an approach which is independent from the various possible underlying radio access technologies. In particular, the security capabilities of the developed architecture comprise user and network authentication, authorization to service access and IP-layer signalling cryptography integrated with application-layer mobility.

This paper proposes and analyzes a Running Variance Metric performance measurement of wireless local area networks and its formal aspects. Our approach evaluates the performance of wireless local area networks in infrastructure mode as well as in ad hoc mode. The Running Variance Metric is used to discover relative traffic loads of available access-points/gateways at the network layer in order to provide connectivity to the wired network. The paper discusses a simulation study. The simulation results demonstrate the usefulness and efficiency of the Running Variance Metric to evaluate the utilization of available access-points/gateways. It is also shown that this metric can be used for hop-analysis in multihop ad hoc wireless networks.

To facilitate a broad range of experimental research on novel protocols and application concepts, we consider an indoor wireless testbed to emulate the performance of real-world networks. A fundamental issue for emulation is the replication of communication links of specified quality. In particular, we need to replicate on the testbed, for every link in the real world, a communication link whose received signal-to-interference-and-noise-ratio (SINR) matches the corresponding link signal-to-noise-ratio (SNR). In this paper, we focus on the downlink SNR mapping associated with a network with a single access point (AP). Four indoor wireless propagation models (commercial buildings with/without line-of-sight path and residential buildings with/without line-of-sight path) and two types of spatial distributions (uniform distribution inside a circular cell and uniform distribution along a line) have been investigated. Based on the characteristics of the indoor testbed, we propose a mapping method with one AP and one interferer, which separates the task into two phases: in the first phase, the best location and transmission power for the interferer node are determined; in the second phase, the topology of receiver nodes is configured by a minimum weight matching algorithm. Through analysis and simulations, we find that when the interferer node is located on the corner across from the AP, we can achieve a mapping range on the order of 57 dB and an average root-mean-square (RMS) mapping error less than 1 dB.

This paper presents the software architecture of the ORBIT radio grid testbed. We describe the requirements for supporting the lifecycle of an experiment and how they influenced the overall design of the architecture. We specifically highlight those components and services which will be visible to a user of the ORBIT testbed.

In this paper we present ORBIT measurement framework and library (OML), which is a distributed software framework enabling real-time collection of data in a large distributed environment. The success of a multiuser distributed testbed facility depends largely on the ease of use, remote access as well as on the ease of collecting useful measurements from experimental runs. OML provides a flexible and dynamic way in which data is collected and made available for realtime access to the experimenters. Application programmers can use simple interfaces provided to transfer measurements and other performance data to a central repository. This paper focuses on the motivation, requirements, design, implementation and real world usage of OML that is designed to provide a scalable, controllable and easy to use mechanism for experimenters to collect useful results from the experiments conducted on the ORBIT testbed.

With the rapid growth in research activity on future wireless networking applications and protocols, experimental study and validation is becoming an increasingly important tool to obtain realistic results that may not be possible under the constrained environment of network simulators. However, experimental results must be reproducible and repeatable for them to be used to compare proposed systems and to build prototypes. In this paper, we address the issue of repeatability in wireless experiments in the Open Access Research Testbed for Next-Generation Wireless Networks (ORBIT) testbed and propose a mechanism to promote reproducible experiments using periodic calibration of the equipment. Several experimental results that capture repeatability in time and space using our initial testbed setup are also provided.

Discrete-event packet-level network simulation is well-known and widely used. Network emulation is a hybrid approach that combines real elements of a deployed networked application-such as end hosts and protocol implementations-with synthetic, simulated, or abstracted elements-such as the network links, intermediate nodes and background traffic. A key difference between the two approaches is that in the former, the notion of time is virtual and is independent of real time, whereas the latter must execute in real time. Emulation gains realism while naturally foregoing complete repeatability; historically, emulation was also tedious to control and manage. We define integrated network experimentation as spatially combining real elements with simulated elements in the same experimental run, each modeling different portions of a network topology. Integrated experiments enable new validation techniques and larger experiments than obtainable by using real elements alone. This paper highlights the key issues in integrated network experimentation and presents some of the design techniques we use in designing, building, and putting into public production use such an integrated environment, running on a space-shared cluster.