[논문]페이딩 현상

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페이딩 현상에 대한 논문입니다.
페이딩 현상을 여러각도 (time domain, frequency domain 등에서 관찰)

목차

1. Introduction
2. Mobile radio propagation: Large-scale fading and small-scale fading.
3. Large-scale fading: path-loss mean and standard deviation
4. Small-scale fading: Statistics and mechanisms.
5. Signal time-spreading viewed in the time-delay domain: The multipath intensity profile
6. Degradation categories due to signal time-spreading viewed in the time-delay domain.
7. Signal time-spreading viewed in the frequency domain: the spaced-frequency correlation function.
8. Degradation categories due to signal time spreading viewed in the frequency domain.
9. Time variance viewed in the time domain: the spaced-time correlation function.
10. The concept of duality.
11. Degradation categories due to time variance viewed in the time domain.
12. Time variance viewed in the Doppler shift domain – The Doppler power spectrum
13. Analogy between spectral broadening in fading channels and spectral broadening in digital signal keying
14. Degradation categories due to time variance viewed in the Doppler shift domain.

본문내용

where d is the distance between the transmitter and receiver, d0 is the relative referenceh corresponds to a point located in the far field of the antenna. Typically, the value of d0 is taken to be 1 km for large cells, 100m for microcells, and 1m for indoor channels. The value of the exponent n depends on the frequency, antenna heights, and propagation environment. For example, in the urban streets the n value can be lower than 2 because of the strong guided wave phenomenon. On the other hands, if there are obstructions between transmitter and receiver, the n value will become higher.
is often stated in decibels like below.
(dB) = Ls(d0) (dB) + 10 n log( d / d0).
cy. Therefore, for exact path loss for the different sites, we should add random variable Xσ which follows zero-mean Gaussian random variable (in decibels).
Lp(d) (dB) = Ls(d0)(dB) + 10nlog10(d/d0) + Xσ(dB).
Xσ is site and distance dependent. The choice of a value for Xσ is often based on measurements. In summary, the parameters are needed to describe path loss due to large-scale fading for an arbitrary location with a specific transmitter receiver separation are the reference distance d0, the path-loss exponent n, the standard deviation σ of Xσ.
Small-scale fading: Statistics and mechanisms.
Fig. 2
Small-scale fading manifests itself in two mechanisms: time-spreading and time-variant fading. Fig. 2 illustrates the consequences of both manifestations by showing the response of a multipath channel to a narrow pulse versus delay, as a function of antenna position (or time, assuming a constant velocity of motion). In Fig.

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