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In order to counteract hostile communication based on the advanced Orthogonal Frequency Division Multiplexing (OFDM) technology, an efficient and unrecognizable jamming technique by failing the OFDM cyclic prefix (CP) functionality is developed in the paper. CP is introduced into OFDM systems to prevent interference caused by the multipath fading, as long as it is no shorter than the channel delay...
A secrecy transmission method with robust power control is investigated in this paper for a downlink two-tier femtocell network, where an eavesdropper attempts to wiretap the legitimate macrocell users. Considering the imperfect channel gains, a probability constraint robust optimization problem is formulated to satisfy the quality-of-service (QoS) of users. We aim to maximize the secrecy rate with...
While 4G is speeding up its steps toward global markets, 5G has initiated its full development to satisfy an increasing demand on mobile data traffic and big data bandwidth. Centralized data processing, collaborative radio, real-time cloud infrastructure, and cloud radio access network (C-RAN), along with their excellent advantages are being sought by more and more operators to meet end-user requirements...
This paper presents a new embedding strategy to extend the performance bound of spread spectrum (SS) based watermarking by introducing more imperceptible distortions measured in the mean square errors (MSE). The potential of the host is sufficiently exploited and utilized to maximize the watermark robustness. This strategy is then realized in audio watermarking by adaptively inverting the host according...
Spread spectrum (SS) modulation is one of the most commonly used methods for data hiding. However, the capacity of SS-based methods is rather limited. To improve the hiding efficiency, this paper presents a method that employs the parallel combinatory spread spectrum (PCSS), in which the hidden data can be transmitted in parallel with a combination of a few pseudo noise sequences. An informed embedding...
In this paper, we propose a filter-and-forward (FF)beamforming strategy in the secondary relays for the one-way cognitive relay network with frequency selective fading channels. Our aim is to optimize the beamforming coefficients and the secondary transmitted power to maximize the SINR at the secondary destination, while satisfying the interference constraint on the primary network and the total relays'...
This paper investigates the cooperative beamforming in the amplify-and-forward-based cognitive relay network. Beamforming coefficients are designed to maximize the sum rate of the secondary users with a total transmit power constraint of the relays and an interference power constraint at the primary receiver. The sum rate maximization problem is firstly solved by characterizing the achievable rate...
This paper proposes a new network-wide optimized time division multiple access (TDMA) scheduling scheme for wireless sensor networks (WSNs). It can simultaneously achieve maximum throughput and fair rate allocation given the requirement of network lifetime. To achieve this object, we first formulate the rate allocation problem based on the Lexicographic Max-Min (LMM) criterion, which takes fairness,...
In this paper, the improved spread spectrum (ISS) modulation is modified and extended to cancel the host interference in the context of watermark decoding with unmatched filtering, where the reference sequence at the watermark decoder does not match with the embedded sequence. Then a robust and transparent audio watermarking scheme based on this extended ISS and a psychoacoustic model is proposed...
This paper describes an informed unipolar spread spectrum (SS) modulation to improve the performance of SS-based watermark extraction with self-synchronization. Compared with bipolar SS, unipolar SS, realized by employing a pair of orthogonal codes to represent the watermark bits, is more robust against the distorted correlation between the received watermarked signal and the reference. The informed...
Digital Signal Processing (DSP) technologies are widely used nowadays. Aiming at the digital signals characteristic parameters in wind tunnel tests, a DSP platform based on MATLAB and C++ Builder mixed programming method is built up. The process technique and the application of the DSP platform in 2.4 m transonic wind tunnel are discussed.
This paper investigates the global optimal multicast routing in the cognitive ad hoc networks, which is based on the directional antenna model. By analyzing directional antenna model and based on the end-to-end performance parameters, a multicast routing algorithm, which is to obtain the global optimal performance and refers to the energy utilization as metric, is proposed. Simulation results show...
Recently, cooperative communication is shown to be a promising approach to achieve spatial diversity. The performance improvement by cooperative communication heavily depends on selecting suitable relay node. Therefore, designing effective relay assignment algorithm becomes critical in wireless cooperative networks. Although many studies focus on relay assignment problem, none of them concerns the...
There is a simple distributed optical fiber sensing system which is used to monitor vibration signal, having an additional sub-loop coupled with main ring by a 3dB coupler. This paper compares three outputting interfered beams, each of them traveling in the sub-ring 0, 1, 2 times separately. Using the simultaneous equations produced by those three outputs, it finds the relation between the interference...
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