Time-sharing of Quantum Key Distribution (QKD) transceivers with the help of optical switches and a central Software-Defined Networking (SDN) controller is a promising technique to better amortize the large investments required to build a Quantum Key Distribution Network (QKDN). In this work, we investigate the implications of introducing Time-Division Multiplexing (TDM) in trusted-relay QKDNs at the wide-area network scale in terms of performance and cost-saving. To this end, we developed both a Mixed Integer Linear Programming (qTDM-MILP) model and a Heuristic Algorithm (qTDM-HA) to solve the allocation of QKD transceivers and network resources for a novel switched QKDN operating scheme: qTDM-QKDN. Our heuristic method provides a close-to-optimal resource planning for the offline problem that computes the minimum number of QKD transceivers and optical switch ports at each node, as well as the number of quantum channels on each link required to satisfy a target set of end-to-end secret-keyrate demands. Moreover, both the model and the heuristic provide the time fractions that each QKD transceiver needs to peer with each neighbor QKD transceiver. We compared our proposed model and heuristic algorithm for cost minimization with non-time sharing QKD transceivers (nTDM) as baseline. The results show that qTDM can achieve substantial cost-savings in the range of 10%–40% compared to nTDM. Furthermore, this work sheds light on the selection of the value for the working cycle T and its influence on network performance. • TDM optimizes QKD networks, enhancing efficiency and cost-effectiveness. • A MILP model and the qTDM-HA ease resource allocation in large-scale QKD networks. • The tools provide outstanding solutions from 10% to 40% in terms of cost-savings. • TDM minimizes the number of dedicated QKD transceivers by using shared ones wisely.

This paper evaluates the performance of the two ETSI non-area forwarding algorithms in the GeoNetworking specification: Greedy Forwarding and Non-Area Contention-Based Forwarding (CBF). Non-area forwarding occurs when a packet is sent to a geographical Destination Area from a node located outside of this area, e.g., when a vehicle wants to alert of hazardous events to other vehicles located in a distant geographical area. The evaluation has been carried out both in urban and highway scenarios and takes into account the complete ETSI Architecture, including the interaction with the Decentralized Congestion Control (DCC) mechanism. We have also compared ETSI-defined mechanisms with optimizations found in the literature. Our main findings are that Greedy Forwarding, when combined with DCC, is extremely ineffective even with optimizations, and Non-Area CBFs (both ETSI CBF and an optimized version called S-FoT+) outperform Greedy Forwarding both in highway and urban scenarios.

This paper evaluates the performance of ETSI ITS Contention-Based Forwarding (CBF) and ETSI Simple GeoBroadcast forwarding while disseminating warning messages over a Geographical Area in highway and urban scenarios. Our experimental evaluation considers the complete ETSI ITS architecture including the Decentralized Congestion Control (DCC) mechanism. We propose an enhanced CBF mechanism, named S-FOT+, which combines several improvements to the ETSI CBF algorithm. S-FoT+ has a similar or better performance than the ETSI forwarding algorithms regarding both reliability and end-to-end delay while requiring much fewer transmissions. The improvements are equally effective and efficient in both urban and highway scenarios with large Destination Areas. Finally, we evaluate the trade-offs that stem from using multi-hop broadcast mechanisms in urban settings with smaller Destination Areas when compared to single-hop broadcast. Results show that multi-hop mechanisms significantly improve coverage at the cost of an increased number of transmissions.

The evolution of the Internet has resulted in the deployment of new applicationlevel solutions to enhance the scalability and efficiency of content dissemination (e.g., content delivery networks and peer-to-peer systems).However, despite of this improvement on performance, the utilization of this type of solutions introduces new security concerns, as a content provider must necessarily delegate the role of distributing the content to third parties, and current security solutions, such as TLS and IPsec, do not allow authenticating the original content provider or the content itself in these scenarios.In this paper, we present SCoT, a transport-layer protocol that allows a content provider to bind protection to content, enabling content authentication at receivers regardless of any third party infrastructures that have been used to disseminate the content.Content authentication procedures are executed transparently to end-user applications.We implemented a fully operational prototype of the protocol in Java, including an API to support the development of SCoT applications.We utilized it to configure an experimentation scenario that served to validate a theoretical analysis of the SCoT throughput and to illustrate the performance that can be achieved in a practical deployment.The paper concludes describing a set of use cases of the protocol.

This paper characterizes analytically the performance of REAchability Protocol (REAP), a network layer end-to-end recovery protocol for IPv6. REAP was developed by the IETF SHIM6 Working Group as part of its multihoming solution. The behavior of REAP is governed by a small number of parameters: three timers, a simple characterization of the application traffic, and the communication delay. The key figure of merit of REAP performance is the time to recover from a path failure as seen by the upper layers, figure that cannot be trivially obtained, despite the apparent simplicity of this reachability protocol. In this paper we provide upper bounds for the recovery time of REAP for different deployment scenarios, applying these analytical results to two interesting case studies, TCP and VoIP traffic.

When there is no wired connectivity, wireless mesh networks (WMNs) can provide Internet access with lower cost and greater flexibility than traditional approaches. This has motivated the design of new protocols and algorithms for WMNs, and recently the deployment of experimental prototypes. In this paper we add to these previous works with the performance evaluation of a first CARMEN deployment, with the following distinguishing features: i) it is an indoor deployment, ii) it is used by real users to connect to the Internet, and iii) it is built using off-the-shelf hardware. The results show that mesh technology can provide users with a satisfactory Internet experience, and motives further research along this line.

This paper details a novel architecture, MobiSplit [17], for managing mobility in future IP based networks. The architecture separates mobility management in two levels, local and global, that are managed in completely independent ways. We describe how such a mobility architecture can be used to support a new paradigm in mobility. By combining the user's identity with a multi physical virtual terminal we treat the movement of people rather than their physical manifestations in one device. We conclude by analyzing the concrete system, built from this new architecture and existing protocols, in terms of scalability, flexibility and security.

The availability of multiple technologies, with micro and macro wireless cells, for network access combined with terminals capable of exploiting such diversity in wireless access requires the development of new mechanisms for optimized handover procedures. Appealing solutions should support network controlled handovers through heterogeneous technologies, preferably combined with a cross-layers two/three design. The IEEE 802.21 working group is currently standardizing the methods and the protocol potentially able to provide such a solution. In this paper we analyze the impact of signaling timing on network controlled handovers execution and performance in this environment. Through an extensive simulation study, we obtain results, that can be exploited in both terminal and handover procedure designs.

WLAN hot-spots are becoming widely spread. This, combined with the availability of new multi-mode terminals integrating heterogeneous technologies, opens new business opportunities for mobile operators. Scenarios in which 3G coverage is complemented by WLAN deployments are becoming available. Thus, true all-IP based networks are ready to offer a new variety of services across heterogeneous access. However, to achieve this, some aspects still need to be analyzed. In particular, the effect of the terminal speed on the detection and selection process of the preferred access network is not yet well understood. In fact, efficiency of vertical handovers depends on the appropriate configuration of mobile devices. In this paper we present a simulation study of handover performance between 3G and WLAN access networks showing the impact of mobile users' speed. The mobile devices are based on the IEEE 802.21 cross layer architecture and use WLAN signal level thresholds as handover criteria. A novel algorithm to dynamically adjust terminals' configuration is presented.

An important requirement for Internet protocol (IP) networks to achieve the aim of ubiquitous connectivity is network mobility (NEMO). With NEMO support we can provide Internet access from mobile platforms, such as public transportation vehicles, to normal nodes that do not need to implement any special mobility protocol. The NEMO basic support protocol has been proposed in the IETF as a first solution to this problem, but this solution has severe performance limitations. This paper presents MIRON: Mobile IPv6 route optimization for NEMO, an approach to the problem of NEMO support that overcomes the limitations of the basic solution by combining two different modes of operation: a Proxy-MR and an address delegation with built-in routing mechanisms. This paper describes the design and rationale of the solution, with an experimental validation and performance evaluation based on an implementation

The network mobility (NEMO) basic support protocol enables mobile networks to change their point of attachment to the Internet, while preserving established sessions of the nodes within the mobile network. When only a nonnested mobile network is considered, the so-called triangle routing is the main problem that should be faced. In mobile IPv6, the route optimisation mechanism solves this problem, and the return routability mechanism aims to limit the security concerns originated because of the route optimisation. Nowadays return routability is considered a weak solution (i.e., based on strong assumptions). In this article we explore different approaches to route optimisation in NEMO and we devise how to adapt some of the terminal mobility solutions to a NEMO environment, where, as we propose, a delegation of signalling rights from the mobile network node to the mobile router is necessary.

This paper proposes an evolved architecture from 3G networks to provide basic and advanced positioning methods for location based services in mobile IPv6-based radio access networks. We start analyzing current status of location-based services (i.e. LBS or LCS) and architectures in 3G networks as well as state-of-the-art research on LBS and mobile Internet. Next we set the requirements the solution should fulfill. We continue proposing the evolved architecture for support of basic and advanced positioning methods, using MIPv6 and HMIPv6 as mobility scenario for the mobile IPv6 based RAN, describing element's functions and changes from current approaches as well as description of the dynamic behavior. We complete the proposal with a bandwidth analysis of the signaling, identifying issues when planning implementation of LCS services in the network.