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Traditional IP multicast suffers from forwarding state scalability problems as the number of concurrent active multicast groups increases. The problem is exacerbated when provisioning QoS since additional information of resource requirement from members must be kept at routers. In this paper, we firstly consider the comparability between various QoS levels and propose a modularized QoS multicasting...
Future network architectures for mesh networks, sensor networks, and hybrid networks include multiple wireless hops with fixed or mobile routers relaying messages between mobile nodes and access points. The vast literature on routing for ad hoc networks is applicable for route discovery between a mobile node and an access point for these multi-hop networks. However, most ad hoc routing protocols rely...
Achieving fair bandwidth distribution among uplink and downlink flows in the infrastructure based wireless local area networks (WLAN) which the distributed coordination function (DCF) mode is difficult. In this paper we present a new control theoretic approach to achieve a fair bandwidth distribution among the flows regardless of the transport protocol used by the flows. In addition, we explore methods...
Adaptive modulation with the goal of minimizing the average transmit power is investigated. This is the dual problem of the well-known problem of maximizing the average spectral efficiency. This is desirable in power limited systems such as mobile and sensor networks. Two main cases are considered: adapting only transmit power and adapting only rate. Appropriate expressions for rate or power control...
Wireless mesh networks exploit multi-hop wireless communications between access points to replace wired infrastructure. However, in multi-hop networks, effective bandwidth decreases with increasing number of hops, mainly due to increased spatial contention. Longer hop length flows suffer from extremely low throughputs which is highly undesirable in the envisioned scenarios for mesh networks. In this...
The performance analysis of multihop wireless networks requires appropriate performance measures in order to take into consideration the intrinsic characteristics of this type of networks. The information efficiency is a measure of how efficiently bits of information are transmitted in multihop networks. In this paper we investigate the performance of a multihop network, by evaluating its total information...
Performance evaluations of an asynchronous DS-BPSK UWB system in standard UWB channels by means of characteristic function (CF) method, standard Gaussian approximation (SGA) and simplified improved Gaussian approximation (SIGA) are presented. The standard UWB channel (proposed by IEEE 802.15.3a task group) is employed in the analysis to reflect the actual channel conditions. Firstly, a bit error rate...
Data and telephone service providers have started considering migration to an IP based environment. This paper presents an unstructured peer-to-peer approach to initiating and maintaining sessions over IP using session initiation protocol (SIP). The offered solution is completely modular and is compatible with traditional server-client based approaches using SIP. The peer-to-peer nature of our design...
Sensitive organizations such as the intelligence community (IC) have faced increasing challenges of insider threats because insiders are not always friends, but can be significant threats to the corporate assets. Statistically, it is accepted that the cost of insider threats exceeds that of outsider threats. Many security technologies have been invented to prevent threats from outsiders, but they...
Key management is a major challenge in the design and deployment of secure wireless sensor networks. A common assumption in most distributed key management schemes is that all sensor nodes have the same capability. However, recent research work has shown that the connectivity and lifetime of the sensor network can be substantially improved if a small number of sensor nodes have more energy capacity...
Computer worms are a serious problem. Much research has been done to detect and contain worms. One major deficiency in most research is that the claims are supported by theoretic models or simulations only and not by realistic tests. Network testbeds such as emulab and deter can be used to conduct worm experiments on networks of a few hundreds nodes. However, setting up such an experiment is not trivial...
On-demand access to remote multimedia content via the Internet is becoming increasingly popular. Applications like video on demand and news on demand are increasingly based on structured multimedia presentations, which give users more options and freedom to interact with the content than just VCR-like operations. For example, authors provide multiple choices for parts of the presentation and the user...
In this paper, we present a thorough and realistic analysis of voice (i.e. audio conferencing) over application-level multicast (ALM). Through flexibility and ease-of-deployment, ALM is a compelling alternative group-communication technique to IP multicast-which has yet to see wide-scale deployment in the Internet. However, proposed ALM techniques suffer from inherent latency inefficiencies, which...
In recent years, a lot of routing protocols have been proposed for mobile ad hoc networks (MANETs). These protocols can employ two types of routing structure, flat or hierarchical. When compared to flat routing protocols, hierarchical ones incur much less routing overhead, which helps provide a better scalability in large-scale MANETs. However, different types of hierarchical routing strategies may...
In wireless networks, secure multicast protocols are more difficult to implement efficiently due to the dynamic nature of the multicast group and the scarcity of bandwidth at the receiving and transmitting ends. Mobility is one of the most distinct features to be considered in wireless networks. Moving users onto the key tree causes extra key management resources even though they are still in service...
In this paper we study the end-to-end complete feedback collection (ECFC) problem in large scale multi-cast applications. We consider the case where each receiver is expected to send feedback in a timely manner without causing implosion at the source site. To address the scalability problem and improve timely feedback collection, we introduce the use of clustering algorithms for feedback collection...
This paper addresses the problem of improving quality of security for real-time parallel applications on heterogeneous clusters. We propose a new security- and heterogeneity-driven scheduling algorithm (SHARP for short), which strives to maximize the probability that parallel applications are executed in time without any risk of being attacked. Because of high security overhead in existing clusters,...
Reserved delivery subnetworks (RDSs) can provide more consistent quality of service to users by reserving bandwidth on an aggregate basis. Besides the benefit of exclusive bandwidth access, there are other potentials to further improve end-to-end performance in an RDS because the end hosts can utilize the knowledge about the underlying networks to achieve better performance than in the ordinary Internet...
Interconnect networks employing wormhole-switching play a critical role in shared memory multiprocessor systems-on-chip (MPSoC) designs, multicomputer systems and system area networks. Virtual channels greatly improve the performance of wormhole-switched networks because they reduce blocking by acting as "bypass" lanes for non-blocked messages. Capturing the effects of virtual channel multiplexing...
Current day wide-issue processors require the fetch engine in the frontend to continuously supply instructions to the issue queue in the backend to extract maximum possible amount of instruction level parallelism (ILP). Further, due to the continuous access of level-1 instruction cache (IL1) for fetching instructions, the power dissipation due to switching activity in IL1 is overwhelmingly high and...
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