lecture6 - Lecture 6 - EE 359: Wireless Communications -...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Lecture 6 - EE 359: Wireless Communications - Fall 2011 Fading Distributions and Duration. Markov Model. Wideband Fading. Doppler and Delay Spread Lecture Outline • Signal Envelope (Fading) Distributions • Level Crossing Rate and Average Fade Duration • Markov Models • Wideband Channel Models • Scattering Function • Multipath Intensity Profile, Delay Spread, and Coherence Bandwidth • Doppler Power Spectrum, Doppler Spread, and Coherence Time 1. Signal Envelope (Fading) Distribution: • CLT approximation leads to Rayleigh distribution (in-phase and quadrature zero mean and jointly Gaussian): p Z ( z ) = 2 z P r exp[- z 2 / P r ] = z σ 2 exp[- z 2 / (2 σ 2 )] , z ≥ . • A LOS component leads to a received signal with non-zero mean. The Rician distri- bution models signal envelope in this case, with K factor dictating the relative power of the LOS component: p Z ( z ) = z σ 2 exp bracketleftBig- ( z 2 + s 2 ) 2 σ 2 bracketrightBig I parenleftBig zs σ 2 parenrightBig , z ≥ 0. • Experimental results support a Nakagami distribution for some environments. Similar to Rician, but can model “worse than Rayleigh.” Model generally leads to closed-form expressions in BER and diversity analysis: p Z ( z ) = 2 m m z 2 m- 1 Γ( m ) P m r exp bracketleftBig- mz 2 P r bracketrightBig , m ≥ . 5 . 2. Level Crossing Rate and Average Fade Duration • Level crossing rate L R is the rate at which a signal envelope crosses the threshold R ....
View Full Document

This note was uploaded on 10/16/2011 for the course ELECTRICAL EE251202 taught by Professor Rejaei during the Spring '10 term at Sharif University of Technology.

Page1 / 3

lecture6 - Lecture 6 - EE 359: Wireless Communications -...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online