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Pilot spoofing attack is a serious threat to timedivision duplex (TDD) orthogonal frequency division multiplexing (TDD-OFDM) system. By employing identical pilot tones as a legitimate receiver, an adversary can contaminate the uplink channel estimation between a transceiver pair. To solve this problem, we in this paper propose an independent component analysis (ICA) based channel estimation and identification...
Aiming at realizing ubiquitous spectrum access and improving the spectrum efficiency in a software-defined network, in this paper, we adopt the concept of cognitive radio and propose a joint subcarrier and power allocation (JSPA) scheme for reciprocally benefited spectrum access with secondary users (SUs) cooperating with primary users (PUs). In our proposed JSPA scheme, SUs adopt the decode-and-forward...
Based on intra-symbol piecewise linear channel model, a novel piecewise equalizer is proposed for OFDM systems in high mobility environment. In this proposed scheme the complex ICI caused by fast fading channels has been resolved as new OFDM subsystems’ simple ISI and lower ICI, respectively caused by the average channel and the time-varying channel over a piece-period. By further employing the characteristics...
In this paper, we study the problem of joint resource allocation in the two-way relay system, where a pair of multi-antenna users wish to exchange information via a multi-antenna amplify-and-forward relay under orthogonal frequency-division multiplexing (OFDM) modulation. We formulate a sum-rate maximization problem subject to a limited power constraint for each individual user and relay. Our resource...
The optimal detector for CP (Cyclic Prefix)-OFDM (Orthogonal Frequency Division Multiplexing) signal with inherent periodic pilots in low signal to noise ratio environments relies on perfect time synchronization. In this paper, we modify the optimal detector and propose a new suboptimal sensing scheme based on pilots estimation (SSS-BPE). In the proposed SSS-BPE, the likelihood criterion and periodicity...
Traditional detection algorithms for frequency selective Orthogonal Frequency Division Multiplexing Vertical-Bell Labs Layered Space-Time system (OFDM-V-BLAST) suffer from high computational complexity. So it's necessary to develop a detection algorithm to minimize the computational complexity and improve BER performance. This paper presents a new reduced-rank detection algorithm based on MMSE Sorted...
In this paper, we investigate an optimal power allocation algorithm for OFDM-based cognitive radio. In the model of power allocation, we set the interference constraints for each primary user, and also take subcarrier sidelobes interference (adjacent channel interference (ACI)) into account, when we use the optimal power allocation algorithm, the transmission capacity of secondary users (SU) is maximized...
This paper presents the evaluation work of the air interface technologies developed for beyond third generation (B3G) mobile communications. Strategy of the evaluation is discussed and a set of performances selected for evaluation is justified. A software platform developed for the evaluation of potential B3G systems is then presented. Preliminary results show that OFDM+MIMO are probably one of the...
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