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Prior work in implementing spectrum sharing scenarios for cognitive radio networks has relied on the unlikely assumption of full cross-channel knowledge made available to the cognitive transmitter (CT) and/or the target primary receiver (PR). However, estimation of this cross-channel knowledge is not only important from a practical stand-point, but also in limiting the real interference power felt...
The scalable extension of H.264, known as Scalable Video Coding (SVC), is recently finalized and adapted by the Joint Video Team. Scalability is achieved in the temporal, spatial, quality (SNR), or any combination of those domains. One example of using video scalability is in saving bandwidth when the same media content is required to be sent simultaneously at different resolutions to support heterogeneous...
This paper presents a multiple-symbol differential spatial division multiple access (MS-DSDMA) system conceived for low-complexity and high-bandwidth-efficiency applications operating in time-varying fading channels, where no channel estimation is required. A low-complexity adaptive multiple-symbol differential interference suppression (MS-DIS) scheme is proposed, which is based on the maximum signal-to-interference-plus-noise...
A novel preamble design is proposed for orthogonal frequency division multiplexing systems, which exploits the variable distance between a pair of training sequences for the transmission parameter signalling. Compared to the existing P1-symbol based preamble for the second generation digital terrestrial television broadcasting standard, the proposed design maintains the high performance and robustness...
In wireless networks, it is important to determine the outcome of packet transmissions for networking protocols. In this paper, we design a transmission outcome classifier for IEEE 802.15.4 wireless networks based on received signal strength indicator and link quality indicator values. Our classifier performs loss differentiation by analyzing statistical differences between weak signal and collision...
Identifying and classifying different network applications is very important for trend analysis, dynamic access control, network security and traffic engineering, while traffic classification is able to classify applications effectively. Current popular methods of traffic classification mainly include machine learning algorithm based on supervised or unsupervised and the method based load. In practical...
In this paper, we consider channel estimation for amplify-and-forward (AF) relay network with orthogonal frequency division multiplexing (OFDM) modulation. We propose a superimposed training strategy at relay that allows the destination node to obtain the separate channel information of the source-->relay link and the relay-->destination link. The proposed training strategy only requires two...
In this paper, we study the achievable rate of the training-based multi-input multi-output (MIMO) systems over time-varying flat fading channels modeled with the $L$-th order autoregressive, AR($L$), process. Using the Bayesian Cram\'{e}r-Rao lower bound (BCRB) to characterize the mean squared error of channel estimation, the achievable rate of the MIMO systems is investigated from the information-theoretical...
This paper examines the use of two-way training in multiple-input multiple-output (MIMO) wireless systems to discriminate the channel estimation (and, thus, data detection) performance between two receivers, namely, a legitimate receiver (LR) and an unauthorized receiver (UR). This work extends upon the discriminatory channel estimation (DCE) proposed in our prior work, where it was previously assumed...
Recently, in multi-antenna wireless systems, the use of artificial noise (AN) in training and data transmission phases has been respectively proposed to achieve performance discrimination between a legitimate receiver (LR) and an unauthorized receiver (UR). For data transmission, an AN-aided beamforming (ANBF) scheme has been proposed where the message is sent towards LR using beamforming while AN...
In this paper, we consider the problem of channel estimation for two-way relay networks (TWRN) under timeselective environment. We first parameterize the time-varying channels by the basis expansion model (BEM) and then propose a novel pilot symbol aided modulation (PSAM) for TWRN. A linear approach to estimate the cascaded channels is designed and the optimal training sequences are derived based...
We analyze the achievable diversity-multiplexing tradeoff (DMT) in MIMO fading channels with two-way channel training. We first consider a typical training scenario, where the transmitter transmits training symbols followed by data symbols, and the receiver performs channel estimation using the training symbols and then uses the imperfect channel estimates to decode the data symbols. It turns out...
QR decomposition with M-algorithm maximum likelihood detection (QRM-MLD) block signal detection can significantly improve the packet error rate (PER) performance of cyclic prefix-inserted single-carrier (CP-SC) multi-input multi-output (MIMO) spatial multiplexing when compared to the frequency-domain spatial filtering based on the minimum mean square error (MMSE) criterion. However, in order to achieve...
This paper studies training-based transmissions over multiple-input multiple-output (MIMO) fading channels in the presence of jamming. Each transmission block consists of a training phase and a data transmission phase. From an information-theoretic viewpoint, we formulate a max-min problem on the energy allocation between the two phases. The legitimate user of the channel aims to design a robust energy...
For single-user MIMO channels with partial receiver CSI, we study the difference between inner and outer bounds of the mutual information achieved with Gaussian codebooks, as well as a related difference between capacity inner and outer bounds. In contrast to previous studies, we assume that the channel estimation error statistics are not given a priori, but depend on the parameters of a training...
In this paper we describe a practical yet effective technique to monitor the amount of bytes that several classes of protocols, such as peer-to-peer, e-mail, etc., transmit over encrypted virtual links, such as IPSec tunnels. The experiments described in this paper demonstrate that our regression-tree-based bandwidth estimator is effective enough to create usage models inherently robust to changes...
In recent years, ``folksonomy''-like systems such as Delicious Social Bookmarking have achieved huge success. User collaboration is the defining characteristic of such systems. For indoor positioning mechanisms, we argue that it is also possible to incorporate collaboration in order to improve system performance, especially for fingerprinting based approaches. In this paper, we propose a robust and...
To manage and monitor their networks in a proper way, network operators are often interested in identifying the applications generating the traffic traveling through their networks, and doing it as fast (i.e., from as few packets) as possible. State-of-the-art packet-based traffic classification methods are either based on the costly inspection of the payload of several packets of each flow or on...
Optimal training design and channel estimation for spatially correlated multi-user multi-input multi-output with orthogonal frequency-division multiplexing (MIMO-OFDM) systems is still an open research topic of great interest. This paper applies tractable semi-definite programming to obtain the optimal training signal for the general case of spatial channel correlations for multi-user MIMO-OFDM. The...
In this paper, we present a novel framework -- it uses the information in kernel structures of a process -- to do run-time analysis of the behavior of an executing program. Our analysis shows that classifying a process as malicious or benign -- using the information in kernel structures of a process -- is not only very accurate but also has very low processing overheads; as a result, this lightweight...
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