73,236 research outputs found
A new inflationary Universe scenario with inhomogeneous quantum vacuum
We investigate the quantum vacuum and find the fluctuations can lead to the
inhomogeneous quantum vacuum. We find that the vacuum fluctuations can
significantly influence the cosmological inhomogeneity, which is different from
what previously expected. By introducing the modified Green's function, we
reach a new inflationary scenario which can explain why the Universe is still
expanding without slowing down. We also calculate the tunneling amplitude of
the Universe based on the inhomogeneous vacuum. We find that the inhomogeneity
can lead to the penetration of the universe over the potential barrier faster
than previously thought.Comment: 16 pages, 9 figure
Data Detection and Code Channel Allocation for Frequency-Domain Spread ACO-OFDM Systems Over Indoor Diffuse Wireless Channels
Future optical wireless communication systems promise to provide high-speed data transmission in indoor diffuse environments. This paper considers frequency-domain spread asymmetrically clipped optical orthogonal frequency-division multiplexing (ACOOFDM) systems in indoor diffuse channels and aims to develop efficient data detection and code channel allocation schemes. By exploiting the frequency-domain spread concept, a linear multi-code detection scheme is proposed to maximize the signal to interference plus noise ratio (SINR) at the receiver. The achieved SINR and bit error ratio (BER) performance are analyzed. A computationally efficient code channel allocation algorithm is proposed to improve the BER performance of the frequency-domain spread ACO-OFDM system.
Numerical results show that the frequency-domain spread ACO-OFDM system outperforms conventional ACO-OFDM systems in indoor diffuse channels. Moreover, the proposed linear multi-code detection and code channel allocation algorithm can improve the performance of optical peak-to-average power ratio (PAPR
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