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The social behavior in cognitive radio networks is studied using analysis tools in social networks. A recommendation system is proposed for cognitive radio, thus incurring the channel preference propagation in the corresponding random geometric network. A mean field based ordinary differential equation is used to describe the dynamics of the channel preference propagation in cognitive radio networks...
In this paper, we are interested in blind and semi-blind identification of multiple-input multiple-output (MIMO) channel for orthogonal frequency division multiplexing (OFDM) systems. Using the sparsity property of wireless channel impulse response, we propose an iterative method which minimizes a cost function to result from the combination of blind or semi-blind criterion and the lp norm. This norm...
In sensor networks, the adversaries can inject false data reports from compromising nodes. Previous approaches for filtering false reports share keys between the source node and its upstream nodes on the path to sink, and rely on intermediate nodes to verify the reports generated by downstream nodes in a probabilistic manner. As a result, false reports have to travel several hops before detected....
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...
This paper presents channel measurements for wireless body area network (WBAN) and provides performance evaluation using the model derived from measurement and the model in the final document of the IEEE802.15.6 channel modeling subcommittee. We measure the radio propagation from 3.0GHz to 5.0GHz which falls in ultra-wideband (UWB) frequency range in an anechoic chamber and give out a static model...
We worked toward development of a low bit-rate encoding algorithm and a low-complexity encoding algorithm for G.718/G.718-SWB, a new standard of International Telecommunication Union - Telecommunication Standardization Sector (ITU-T). Many key technologies including Band-Selective Shape-Gain Coding (BS-SGC) were developed for the standard. BS-SGC can encode the audio signal efficiently at a low bit-rate...
In this paper, we consider a novel compressed correlation-matching (CCM) approach for spectrum sensing of wideband sparse signals. We derive a general closed-form estimate of the wideband sparse signal level from compressed observations, while providing physical interpretation of the problem. The formulation allows straightforward application to signal processing problems of interest, such as generalized...
With the rapid advance in the technology area of data storage, storage capacities have increased substantially while the price has been dropping fast. Motivated by this trend, it has been proposed in the Cache-and-Forward architecture that storage is incorporated into each intermediate CNF router. Content can be cached at CNF routers when they flow through the network, and therefore, routers can serve...
In order to provide communication services in Delay Tolerant Networks (DTNs) where it lacks of end-to-end paths between the communication sources and destinations, a variety of routing schemes have been proposed. Consequently it is significant to accurately evaluate their performance to show their advantages and inferiority. At the same time, the energy is very limited in a large number of DTNs, such...
In this paper, we consider an opportunistic access to the spectrum resources in wireless networks. The resources are adopted by the network nodes in a distributed manner, i.e. based on their local channel quality information. The competition of nodes for available resources is modeled as a game. To coerce the desired behavior of the competitors having no information on the other players, pricing (taxation)...
Energy-efficient link adaptation is studied on a slowly varying Rayleigh fading channel assuming perfect CSI at the receiver but no CSI at the transmitter, except for the statistical characterization. Both circuit power and power dissipated in the power amplifier are considered and the energy consumption per bit is minimized over bandwidth, transmission power, and transmission rate. It is shown that...
Over the last years, the research community has been deeply concerned about the scalability issues that the Internet routing is facing. In this paper we study the economic incentives for the Global Routing Table (GRT) explosive growth by considering a commons model in which the GRT is a public resource. In particular, we analyze the motivations the ASes have for deaggregating their assigned address...
We address the Primary User (PU) detection (spectrum sensing) problem, relevant to cognitive radio, from a finite random matrix theoretical (RMT) perspective. Specifically, we employ recently-derived closed-form and exact expressions for the distribution of the standard condition number (SCN) of uncorrelated and semi-correlated random dual Wishart matrices of finite sizes, to design Hypothesis-Testing...
Multimedia sensor networks (MSNs), which allow capturing acoustic and visual information, provide an unprecedented opportunity for variety of applications. This paper investigates the heterogeneous coverage problem in MSNs, i.e., how many multimedia sensors should be deployed to guarantee that each point in the monitored region is covered by multiple types of heterogeneous sensors. It is different...
Radio Resource Management(RRM) has become critical with the current growth in the development of new technologies and services in the field of cellular communications. Efficient management of available radio resources and the possibility of dynamically selling unused spectrum are crucial challenges for the telecom operators. We propose an auction model for efficiently marketing radio resources and...
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...
In this treatise, we propose a novel family of Asynchronous Cooperative Linear Dispersion Codes (ACLDCs), which is capable of maintaining full diversity in cooperative scenarios even at the presence of asynchronous reception. The linear dispersion structure is employed in order to accommodate the dynamic topology of cooperative networks, as well as to achieve higher throughput than conventional space...
In this paper, we propose a new packet routing scheme, i.e., a combined digital and analog network coding scheme (DNC-ANC) suitable for multiple unicast scenario. In this respect, we consider a random access WLAN comprised of single and multi-hop unicast sessions. Then we modify the MAC scheme in order to enable ANC. In order to evaluate the effect of the proposed DNC-ANC scheme analytically, we employ...
In this paper, we consider the tracking of mobile terminals based on the received signal strength (RSS) measured from several base stations. The spatial correlation of the random shadowing is exploited in order to improve the position tracking. We define an auto-regressive (AR) model of the temporal evolution of the shadowing. This model allows for performing a joint tracking of the position and the...
In this paper, we propose an iterative lowcomplexity carrier frequency offset (CFO) compensation algorithm based on the conjugate gradient (CG) method for uplink orthogonal frequency division multiple access systems. In general, a linear minimum mean square error (MMSE) CFO compensation algorithm is simple and efficient, but it requires an inverse operation to compute the MMSE solution of the CFOinduced...
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