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In this paper, we propose a p-weighted noise reduction algorithm to improve the accuracy of channel estimation in Orthogonal Frequency Division Multiplexing (OFDM) systems. A SNR and speed adaptive weighting factor p is introduced, which can efficiently reduce the noise. After that, an exact expression of the optimal value of p under piecewise linear interpolation in time domain are derived, as well...
In this paper, we study the channel estimation algorithms for the downlink of 3GPP LTE systems. By using computer simulation, the pilot signal assisted channel estimation algorithms based on least square (LS) and linear minimum mean square error (LMMSE) criteria, together with channel interpolation based on piecewise-linear interpolation and DFT based interpolation are studied. By analyzing simulation...
Recursive expectation-maximization (EM) algorithm along with stochastic approximation is employed in this paper to estimate unknown time-invariant/variant parameters. In addition, we modify the conventional Viterbi algorithm used in space-time encoder under the MIMO system, and give the recursive metric equation. The modified Viterbi algorithm can be used in the receiver when the MIMO channel information...
Long term evolution (LTE) is envisioned to be a key technology for the 4G wireless communication. In LTE systems, each user (UE) detects the surrounding base stations by searching the primary and secondary synchronization channel symbols in the received signal. Searching and tracking neighboring base stations is of great interest for UEs' handover and other applications such as base station cooperation...
In this paper, a cooperative spatial multiplexing scheme is considered for dynamic relay networks. We assume that each relay node is equipped with a single antenna. To obtain spatial multiplexing gains, the distributed multiple-input multiple-output (MIMO) scheme, in which cooperating nodes act as elements of a multi antenna system, has been proposed in many papers. Since the nodes need to know their...
Cognitive radio (CR) is a dynamic spectrum access technology as a solution to spectrum under-utilization problem in some licensed bands. Operating over an exceedingly wide spectrum, CR systems usually adopt multi-carrier modulation (MCM) to implement flexible channelization. Consequently, efficient channel allocation scheme becomes extremely important to an MCM based CR (MCM-CR) system. In this paper,...
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