Search results for "ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS"
showing 10 items of 449 documents
Call Admission Control in Single and Two-Tier Cellular Networks
2010
We consider four strategies for call admission control (CAC) in single and two-tier cellular networks, which are designed to ensure advantage of handover calls: dynamic redundancy (cutoff priority scheme), partial dynamic redundancy (fractional guard channel scheme), static redundancy (rigid division-based CAC scheme) and restriction of the number of new calls admitted (new call bounding scheme). We show the advantage of dynamic reservation by numerical analysis. We strictly prove it in the case of two-channel system with losses.
An Integrated Multi-service Software Simulation Platform: SIMPSONS Architecture
2005
This paper describes SIMPSONS (SIp and MPls Simulations On NS-2), which is a software platform for simulating multiple network scenarios, such as Telephony Over IP (TOIP), and multi-services networks extending the functionalities of Network Simulator NS-2. The innovative aspects of SIMPSONS is the complete integration of control protocols and traffic engineering mechanisms inside the same simulation tool. In fact, next generation networks must meet basically two fundamental requirements: support of Quality of Service (QoS) and Traffic Engineering (TE) functionalities. SIMPSONS is able to simulate DiffServ, MPLS, OSPF and SIP and their interaction in everything TOIP scenario. So with this po…
Breaking layer 2: A new architecture for programmable wireless interfaces
2012
This paper introduces a new architecture for programmable wireless interfaces, aiming at responding to the emerging request of wireless access flexibility and adaptability. Instead of implementing a specific MAC protocol stack, the proposed architecture supports a set of programmable services, devised to customize the wireless access operations according to specific network and application scenarios. The services are composed by means of simpler functions, which in turns work on system primitives (i.e. elementary non-programmable functionalities, natively provided by the system) dealing with the physical transmission and reception of the frames. Our approach significantly differs from softw…
Inter-provider AAA and Billing of VoIP Users with Token-based Method
2007
With the increasing popularity of wireless LAN technology, providers of real-time voice over IP (VoIP) services, known as voice service providers (VSP), are asking for roaming solutions and AAA (Authentication, Authorization and Accounting) methods that allow users to use their services from any available public Internet access network. In this paper we propose an AAA and billing architecture that allows users of VSPs to have access to the Internet from wired and wireless access networks provided by both traditional carriers, such as 3G providers, and wireless local access network (WLAN) providers. We propose a token-based AAA method that allows users of VoIP services to have their VSPs as …
Secure interworking with P2PSIP and IMS
2010
In this paper, we propose a secure system model for interconnection between P2PSIP and IMS domains. The interworking solution is based on P2P-IMS GateWay (PIGW), which acts as a normal peer in P2PSIP network and a 3rd party IMS Application Server (AS) in IMS network. The security is achieved by implementing Chord Secure Proxy (CSP) and enhanced with subjective logic based trust model. We also implement this system model and analyze it in several aspects: number of hops and delay, trust improvement and protection against malicious or compromised intermediate peers. We conclude that the proposed architecture is feasible and improves security. As far as we know our research is the first study …
Trust enhancement of P2PSIP communication systems
2011
Today, peer-to-peer (P2P) session initiation protocol (SIP)-based communication systems have attracted much attention from both academia and industry. The decentralised nature of P2P might provide the distributed P2P communication system without help of the traditional SIP server. However, it comes to the cost of reduced trustworthiness and may cause security problems, e.g., privacy leaks, unpredictable availability, etc. In this paper, we investigate P2PSIP security issues and propose a subjective logic-based trust model that offers trust-based security services during P2PSIP session establishment. The main issues considered in this model include opinion calculation, opinion maintenance, d…
Analysis and Simulation of the Signaling Protocols for the DiffServ Framework
2006
This paper considers signaling protocols for the DiffServ QoS framework. Originally, DiffServ had no standardized signaling solution, which resulted in the static configuration for the DiffServ domain. However, the dynamic allocation of resources within the domain allows to ensure the per-flow QoS guarantees and achieve better performance. At the moment, several signaling solutions for DiffServ framework are available. Thus, it is crucial to analyse these solutions and interconnections between them. In particular, the RSVP, aggregated RSVP, GIST, COPS, and SIP protocols will be considered. The simulation comprises several scenarios that present that the dynamic allocation of resource within…
Realizing airtime allocations in multi-hop Wi-Fi networks: A stability and convergence study with testbed evaluation
2019
Abstract REACT is a distributed resource allocation protocol used to negotiate a max–min allocation of airtime for multi-hop ad hoc wireless networks. Two approaches are proposed for a node to realize its REACT allocation in a contention-based MAC protocol. This is achieved by tuning its contention window to a value that corresponds to its allocation. Only a change in the allocation, due to a change in local traffic requirements or local network views, results in re-tuning. The approaches for tuning are implemented in commercial Wi-Fi devices and their stability and convergence are studied experimentally in the w-iLab.t wireless network testbed. These properties are also studied analyticall…
Coexistence between IEEE802.15.4 and IEEE802.11 through cross-technology signaling
2017
When different technologies use the same frequency bands in close proximity, the resulting interference typically results in performance degradation. Coexistence methods exist, but these are often technology specific and requiring technology specific interference detection methods. To remove the root cause of the performance degradation, devices should be able to negotiate medium access even when using different technologies. To this end, this paper proposes an architecture that allows crosstechnology medium access by means of a Time Division Multiple Access (TDMA) scheme. In order to achieve cross-technology synchronization, which is required for the TDMA solution, an energy pattern beacon…
MAC design on real 802.11 devices: From exponential to Moderated Backoff
2016
In this paper we describe how a novel backoff mechanism called Moderated Backoff (MB), recently proposed as a standard extension for 802.11 networks, has been prototyped and experimentally validated on a commercial 802.11 card before being ratified. Indeed, for performance reasons, the time critical operations of MAC protocols, such as the backoff mechanism, are implemented into the card hardware/firmware and cannot be arbitrarily changed by third parties or by manufacturers only for experimental reasons. Our validation has been possible thanks to the availability of the so called Wireless MAC Processor (WMP), a prototype of a novel wireless card architecture in which MAC protocols can be p…