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Dynamic spectrum access (DSA) is an important design aspect for the cognitive radio networks. Most of the existing DSA schemes are to govern the unlicensed user (i.e., secondary user) traffic in a licensed spectrum without compromising the transmissions of the licensed users, in which all the unlicensed users are typically treated equally. In this paper, prioritized unlicensed user traffic is considered...
Online social search (OSS) brings forth a new way to harness the Internet for answers. In this paper, we study the non-cooperation problem in OSS. We propose an analytical model that captures the behavior of OSS nodes, and, from a gaming-strategy point of view, analyze various strategies an individual node can utilize to allocate its awareness capacity. Based on this we derive the Pareto inefficiency...
Location privacy is one of the Quality of Privacies (QoP) in vehicular ad hoc network (VANET) and imperative for the VANET's full flourish. Frequent pseudonym changing can provide a promising solution to achieve location privacy, however if the pseudonyms are changed in an improper occasion, the solution is ineffective. In this paper, to improve the effectiveness of this kind of solution, we first...
Providing incentives for user contribution has been one of the primary design goals of Peer-to-Peer systems. The newly-emerged BitTorrent private communities adopt Sharing Ratio Enforcement (SRE) on top of BitTorrent's incentive mechanism, Tit-For-Tat, in order to strictly enforce a minimum contribution a member has to provide, in relation to the amount of service it has received. In this paper, we...
A fundamental choice in femtocell deployments is the set of users which are allowed to access each femtocell. Closed access restricts the set to specifically registered users, while open access allows any mobile subscriber to use any femtocell. The main results of the paper are lemmas which provide expressions for the SINR distribution for various zones within a cell as a function of this MBS-femto...
During the last decade of P2P research a lot of attention has been given to incentive mechanisms. While centralized incentive mechanisms are straightforward in their design, a long term challenge has been to create a decentralized incentive mechanism that can be used to effectively induce cooperation and reduce freeriding. While there have been many proposals of such mechanisms based on the spreading...
In wireless sensor networks (WSNs), sensor nodes are typically power-constrained with limited lifetime, and thus it is necessary to know how long the network sustains its networking operations. We consider the network lifetime as the time until that a majority of functional nodes remains connected of one another, forming a giant component, in the network. We then analytically examine such network...
We investigate the secure connectivity of wireless sensor networks under the pairwise key distribution scheme of Chan et al.. Unlike recent work which was carried out under the assumption of full visibility, here we assume a (simplified) communication model where unreliable wireless links are represented as on/off channels. We present conditions on how to scale the model parameters so that the network...
Compared to real cellular systems where users are spatially distributed and interference levels vary by several orders of magnitude over a cell, in the Wyner model user locations are fixed and the interference intensity is characterized by a single fixed parameter. Although it is a fairly extreme simplification, the Wyner model has been extensively used to analyze cellular networks. Does it capture...
We present an analytical model for end-to-end (e2e) channel systems with lossy communication (E2E-CSLC) of multihop wireless networks using Quasi-Birth Death models (QBDs). Moveover, we show that the state set of level 0 of E2E-CSLC model, i.e., S0, is an attractor according to the special structure of QBDs, which is the foundation of studying the probabilistic reachability for E2E-CSLC. Based on...
In this paper, we examine the effects of a power saving scheme in Passive Optical Networks (PON). Buffers in network equipment have been a cause of concern since they consume significant power. In a PON, the Optical Network Unit (ONU) buffers client node packets before forwarding to the Optical Line Terminal (OLT). We propose a scheme that reduces or eliminates buffers in the ONU thereby providing...
In this paper we consider a cognitive radio network in a heterogeneous multi-channel scenario where channels are different in terms of achievable bit rates. Upon arrival licensed users (PUs) will occupy first the channels with higher achievable rates. As a result, secondary users (SUs) will see a set of channels which are different not only in their physical capacities but also in the activity profile...
BitTorrent has been a very successful peer-to-peer (P2P) file-sharing application, and several BitTorrent-based P2P video streaming systems have been proposed in the literature. Nowadays, network address translation (NAT) has been widely used since it reduces the usage of IP addresses, but it is also considered as a factor that degrades the performance of P2P systems because NAT limits the direction...
In wireless networks using hybrid MAC, nodes can reserve time periods inside scheduling cycles, and the time which is not reserved can be used by all the nodes through contention-based access. The hybrid MAC is attractive because it can provide satisfactory QoS by resource reservation and also achieve high channel utilization by multiplexing gain in the contention periods. However, we are still lacking...
Relay is used in LTE-Advanced cellular networks to assist eNB(evolved Node Base-station) for coverage extension and throughput enhancement. Compared to eNB, relay is advantageous on both equipment cost and site cost. How to deploy relays to maximize the performance gain with a reasonable cost subject to a number of system constraints such as interference caused and backhaul subframe allocation is...
Theoretical analysis has long indicated that feedback improves the error exponent but not the capacity of memoryless Gaussian channels. Recently, Chen et al. demonstrated that an incremental redundancy scheme can use noiseless feedback to help short convolutional codes deliver the bit-error-rate performance of a long blocklength turbo code, but with much lower latency. Such a latency improvement is...
In this paper, we propose an analytical model to evaluate the maximum stable throughput of a cognitive IEEE 802.11-based WLAN sharing the downlink band of a cellular network. Our model has been found on an open queueing network which includes both asymmetric and non-saturated aspects of secondary nodes as well as the time-varying nature of the channel due to intermittent primary nodes. By mapping...
Analytical formulations of the throughput of cognitive multi-channel MACs with perfect and imperfect sensing are presented. Both imperfect concurrent sensing and imperfect sequential sensing schemes are considered. A discrete time Markov chain is used to model the number of communicating node pairs in the MAC protocols. The throughput of the MAC protocol with perfect sensing is expressed as a function...
A novel queuing model in this paper is proposed to provide a tool for performance evaluation to IEEE 802.15.4 Medium Access Control (MAC) protocol with sleep mode enabled. IEEE 802.15.4 node with sleep mode enabled behaves in a different way from other queuing models because the node goes to sleep periodically and thus packets arriving in sleep period accumulate in the beginning of the active portion,...
In this paper, an analytic model is built to derive a closed form broadcast packet reception rates in IEEE 802.11 based two-dimensional (2-D) mobile ad-hoc networks (MANETs), which is the extension of 1-D MANET analytical model in [4]. The analytic model takes two straight parallel line geometry, IEEE 802.11 backoff counter process, hidden terminal problem, message arrival interval, and fading transmission...
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