JANUS: A Framework for Distributed Management of Wireless Mesh Networks

Abstract — Wireless Mesh Networks (WMNs) are emerging as a potentially attractive access architecture for metropolitan-scale networks. While research on WMNs has been up to a large extent confined to the study of efficient routing protocols, there is a clear need to envision new network management tools, able to sufficiently exploit the peculiarities of WMNs. In particular, a new generation of middleware tools for network monitoring and profiling must be introduced in order to speed up development and testing of novel protocol architectures. Currently, manage-ment functionalities are developed using conventional central-ized approaches. The distributed and self-organizing nature of WMNs suggest a transition from network monitoring to network sensing. In this work, we propose JANUS, a novel framework for distributed monitoring of WMNs. We describe the JANUS architecture, present a possible implementation based on open-source software and report some experimental measurements carried out on a small-scale testbed. Index Terms — wireless mesh networks, network management, distributed hash table, overlay networks, publish-subscribe sys-tems I

A Simulation Study of Scalable TCP and HighSpeed TCP in Geostationary Satellite Networks

This paper investigates the performance of two TCP enhancements (i.e., Scalable TCP and HighSpeed TCP), recently proposed for high-speed backbone networks with a very large bandwidth-delay product, in a geostationary satellite environment. Both persistent and elastic traffic patterns are considered, performance being evaluated in terms of TCP throughput and mean session delay, respectively. The impact of channel characteristics (packet error rate, correlation between successive losses) is widely discussed. Fairness issues are also accounted for, together with the impact of some system parameters, such as the satellite link bandwidth. Extensive comparisons are carried out among Scalable TCP, HighSpeed TCP and other congestion control schemes. The obtained results show the soundness for the use of such protocols in geostationary satellite networks. Indeed, both protocols permit to improve the performance of TCP connections in a wide range of channel conditions, showing (especially Scalable TCP) to be able to cope well with rainy conditions and to exploit a future increase in the satellite link capacity. 1 I

Mathematical Analysis of Bluetooth Energy Efficiency

In this paper, we propose a mathematical framework for the analysis of Bluetooth systems energy efficiency. The dynamic of the system is modelled by means of a finite state Markov chain (FSMC). Hence, we resort to the renewal reward theory to derive an estimation of the average throughput and energy efficiency achieved by the different packet formats, both for AWGN and Rician fading radio channels. System behavior is investigated under a wide range of parameters, like receive-- correlator margin, average signal to noise ratio and Rice factor. The analysis we present may provide precious guidelines for the design of energy--efficient Segmentation--and--Reassembly modules and baseband polling algorithms for Bluetooth piconets. KEYWORDS Bluetooth, energy efficiency, ad-hoc networks I. INTRODUTION Bluetooth [1], [2] is an emerging radio technology that is expected to play a leading role, in the near future, in the field of short--range personal communications. Although Bluetooth can hardly compete in terms of transmission speed with other existing radio technologies, like IEEE 802.11b, it is definitely competitive in terms of energy consumption. Bluetooth, indeed, was designed to be integrated in portable, battery driven electronic devices, for which energy saving is a key issue

Abstract A wireless extension of Profibus DP based on the Bluetooth radio system

Wireless networks are beginning to be employed in industrial automation systems as extensions of field networks (fieldbuses), in order to link devices which may not be equipped with a wired connection. In this way, all the benefits deriving from the use of a fieldbus may be maintained. This paper investigates a wireless extension of Profibus DP, one of the most popular fieldbus standards, based on the Bluetooth radio interface. After a description of how the data link layer services of Bluetooth could be used to implement the Profibus DP functions, we present a theoretical network performance analysis. The results obtained are then validated by means of numerical simulations

Performance characterization of a Bluetooth piconet with multi-slot packets

Abstract — In this paper we present a framework for performance evaluation of a Bluetooth piconet using multislot packets. In particular, under some classical assumptions, we develop a model of a Bluetooth network and derive the complete statistics of the one–hop delay, and other significant metrics such as the channel utilization parameter. Stability conditions are investigated and it is shown that the use of multi–slot packets enlarges the achievable rate region. Simulations results are then shown, which validate the proposed analysis. Index Terms — Bluetooth, S.A.R., multislot packets, performance evaluatio

A Framework for Opportunistic Forwarding in Disconnected Networks

Abstract — In this paper, we analyze the performance of a family of opportunistic forwarding schemes (the K-copy relaying strategies) over disconnected wireless networks. We introduce a classification of mobility models based on their dynamic properties, and characterize the M 2 (Marks-Memoryless) class. Statistical tools are combined with numerical simulations to show that some of the most used mobility models in the literature fall within the M 2 class. A mathematical framework is provided for evaluating the performance of opportunistic forwarding schemes in the presence of M 2 mobility, and it is shown that the finiteness of the mean time necessary to deliver a message depends only on the mobility characteristics and not on the relaying protocol specification. Index Terms — wireless networks, opportunistic forwarding, disconnected networks, mobility models. I

A Soft-QoS Scheduling Algorithm for Bluetooth Piconets

In this paper we present a scheduling scheme for supporting soft--QoS in Bluetooth piconets. The slave nodes negotiate with the master the target QoS level, expressed in terms of minimum bandwidth and maximum delay. The QoS requirements come along with a soft--index that determines the degree of tolerance on the target QoS that a slave is ready to accept for the intended connection: the higher the soft--index, the looser the QoS requirements. The algorithm keeps a dynamic estimation of the satisfaction of each node, defined as the fraction of packets that satisfy the QoS requirements. Accordingly, the master dynamically tunes the slaves priorities. Such priorities are then used to decide which slave will be polled at the next available slot. The effectiveness of the proposed algorithm is supported by numerical simulations, which show how the use of the soft-indexes and the dynamic estimation of the users satisfaction lead to a more efficient use of the system resources. KEYWORDS Bluetooth, QoS, ad-hoc networks I