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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....
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...
We consider an opportunistic channel access problem over multiple primary bands. We exploit primary ACK/NAK packets overhearing to overlay secondary communications on top of permanently busy primary channels. Through the theory of multi-armed restless bandit processes (MARB), we prove optimality of the myopic policy with a simple structure that does not require channel state-transition probabilities...
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 this paper, we investigate the transmission completion time minimization problem in a two-user additive white Gaussian noise (AWGN) broadcast channel, where the transmitter is able to harvest energy from the nature. The harvested energy is modeled to arrive at the transmitters randomly. In this paper, under a deterministic system setting, we assume that the energy harvesting times and harvested...
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...
This paper presents a novel adaptation of the score-based scheduling principle along with a method for trading-off bandwidth for energy efficiency for use in Long Term Evolution (LTE) systems. The score-based principle is adapted to make use of both a relative and absolute energy efficiency metric. This results in flexible energy efficient scheduling that preserves the quality of service (QoS), as...
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...
Ad hoc networks rely on the mutual cooperation among individual nodes to achieve network-wide objectives. However, individual nodes may behave selfishly in order to maximize their own benefits without considering the global benefits of the network. One approach to incentivize nodes cooperation for better global benefits is to establish trust relations among nodes to guide their decision making. In...
Simulation, point estimation, and interval estimation of the bit error rate are rigorously examined. Exact confidence intervals based on the F-distribution approximation for the binomial and negative binomial distributions are derived. Simulations demonstrate 1) that the analysis gives accurate confidence intervals for bit error rate estimators and 2) that the performance of the binomial and negative...
We consider a general wireless channel model for different types of code-division multiple access (CDMA) and space-division multiple-access (SDMA) systems with isometric random signature/precoding matrices over frequency-selective and flat fading channels. We derive deterministic approximations of the Stieltjes transform, the mutual information and the signal-to-interference-plus-noise ratio (SINR)...
Random Linear Network Coding (RLNC) provides a theoretically efficient method for coding. The drawbacks associated with it are the complexity of the decoding and the overhead resulting from the encoding vector. Increasing the field size and generation length presents a fundamental trade-off between packet-based throughput and operational overhead. On the one hand, decreasing the probability of redundant...
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...
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 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...
Many network pricing schemes have been proposed in recent years for spectrum/network service access. Most of them model the spectrum/service access problem as a cooperative game, where the spectrum/network service is assumed to be open to every user. However, few of them have considered the scenarios that the spectrum/network service is private. In this paper, we study the network pricing of private...
Information flow analysis is a powerful technique for reasoning about the sensitive information exposed by a program during its execution. While past work has proposed information theoretic metrics (e.g., Shannon entropy, min-entropy, guessing entropy, etc.) to quantify such information leakage, we argue that some of these measures not only result in counter-intuitive measures of leakage, but also...
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