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In target searching stage of radar seeker in modern encounter, the transmitted signal is required to have characteristics of high resolution, low probability of intercept and high Doppler tolerance. In order to overcome the disadvantage of OFDM signal's low Doppler tolerance, a new type of multicarrier signal with nonuniform frequency density is proposed, whose subcarriers and amplitude weighting...
In this paper, an algorithm for accurate distance estimation of a vehicle to a road side unit (RSU) in urban multipath environments is presented. The algorithm is based on spatial filtering using a uniform circular array (UCA) antenna and a cross correlation based time delay detection. The time base for the cross correlation is built using Global Navigation Satellite System (GNSS) based positioning...
This paper proposes the theoretical derivation method of the Shannon capacity for nonlinearly amplified uplink Orthogonal Frequency Division Multiple Access (OFDMA) in the presence of terminal mobility. In our theoretical derivation, the impact of the intercarrier interference (ICI) arising from terminal mobility as well as the multiuser interference (MUI) caused by nonlinear amplification of the...
In this paper, dynamic resource allocation and multicast routing algorithms are proposed for elastic optical networks (EONs). The proposed algorithms find the shortest path trees by modeling either the amount of free spectrum in each link or the link length as the cost function of routing method. The proposed algorithms are simulated in the dynamic operation scenario over the so called US Backbone...
This paper proposes a generalized frequency division multiplexing (GFDM) modulation scheme that transmits a signal with different subcarrier bandwidths. In a receiver, the GFDM signal is demodulated by using a zero forcing (ZF) algorithm or a minimum mean square error (MMSE) algorithm and the BER performance of these algorithms is related to the condition number of a modulation matrix. This matrix...
A multimode 850-nm VCSEL with its relative-intensive-noise suppressed to −145 dBc/Hz is employed for directly encoded 56-Gbps 16-QAM OFDM and 22-Gbps PAM-4 transmissions with corresponding BERs of 3.2×10−3 and 1.9×10−10, respectively.
A laser diode (LD) based Li-Fi transmitter using phosphor diffuser diverged 450-nm blue LD for white-lighting and 5.2-Gbit/s OFDM with EVM of 17.3%, SNR of 15.3 dB and FEC qualified BER of 3.1×10−3 is demonstrated.
We experimentally compare OFDM and Single-carrier modulation in a large-capacity optical-wireless signal delivery system at W-band. We conclude that OFDM is more suitable in a scenario of relatively short wireless distance and limited receiver bandwidth.
V-band gapless OFDM RoF system with power detector down-conversion is proposed. We propose and successfully employ a novel Volterra nonlinear compensation to mitigate signal-to-signal beating interference, resulting in 22% data rate improvement with bit-loading algorithm.
We demonstrate a wideband OFDM transmission, using electrical IQ-mixing and signal combining. Transmission rates of 154.9 Gb/s over 2 km of SSMF were achieved with an IM/DD system on a single wavelength and a single polarization.
We demonstrate an all-electronic digital-to-analog converter (DAC) with 100-GHz electrical bandwidth sampling at 240 GS/s, based on digital bandwidth interleaving. We test the DAC by generating up to 190-GBaud Nyquist shaped pulse amplitude modulated (PAM).
Wavelet-OFDM based on the discrete wavelet transform is a multicarrier modulation technique of considerable interest, due to its good performance in several respects such as the peak-to-average power ratio and the interference cancellation, as investigated in the literature. More specifically, the Haar wavelet has been proposed by various researchers as the most attractive wavelet for data transmission...
We propose a method for channel estimation in orthogonal frequency division multiplexing (OFDM) systems with an array of receiving elements. In contrast to traditional methods, which target the equivalent sample-spaced channel taps, this method targets the physical propagation paths whose delays are not restricted to the sample-spaced grid. The path delays are estimated jointly with the path gains...
This paper presents our research in developing high performance but low complexity MIMO decoders for the newest WLAN, i.e. 802.11ac. K-best and Trellis methods are proposed to develop the MIMO decoders. Their performances are observed and compared to MIMO decoders which are based on linear and optimal methods, i.e. ZF, MMSE, and ML. Run test of 2×2 MEMO, 64-QAM, Coding rate 3/4, and 40MHz of bandwidth...
The energy efficiency of underwater acoustic carrier aggregation in Orthogonal Frequency Division Multiplexing (OFDM) systems is studied and an energy-efficient aggregation bandwidth selection method is proposed. Via simulations it is found that (i) the aggregation bandwidth has an optimal value maximizing the energy efficiency, (ii) this optimal aggregation bandwidth decreases with increasing distance,...
Underwater acoustic communications based on Orthogonal Frequency Division Multiplexing (OFDM) are realized usually in high frequency for high communication rate, and the channel and hardware conditions make our communication band is limited. Conventional modulation of these OFDM scenarios are FFT, it will face the problem of oversize FFT number and large computation complexity in the conditions of...
Future wireless communication systems demand high data rates. It increasingly adopts an orthogonal frequency division multiplexing (OFDM) to consume the available spectrum efficiently. To obtain a good performance, such systems need to know the impact of channels to achieve the communication quality. It is a matter of how to extract transmitted data in an efficient way. The system employs pilot symbols...
Nowadays, most wireless devices are well suited for the fast evolving technology of Software-Defined Radios, which is a radio technology that most wireless signal processing components are implemented digitally in software. This paper presents a low cost, portable, and flexible frequency hopping signal record and playback system based on a general purpose software radio front end, the Universal Serial...
A dual-polarized horn antenna is proposed for K-band wireless communication in this paper. It has a common radiation aperture and two orthogonal wave ports. Hybrid feeding technology of waveguide and microstrip is adopted in the design. High isolation between the two ports can be achieved by adding the waveguide mode cut-off windows. The antenna is able to work well within the relative bandwidth of...
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