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Chapter 2 無線電接取技術. Radio Access Technologies. 課程目標. 這個章節針對行動通訊中無線電傳輸的基本原理、電磁波運作的特性與方式,進行入門的介紹。內容包括: 比較類比信號( analog signal )與數位信號( digital signal )的傳輸方式 討論無線電波傳輸的情形以及模型的建立 簡介調變( modulatoin )技術。 就電磁波干擾問題的解決方案,針對通道編碼( channel coding )與交錯放置( interleaving ) 加以介紹。. 章節目錄. - PowerPoint PPT Presentation
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Chapter 2 Radio Access Technologies
analog signaldigital signal modulatoinchannel codinginterleaving
Section 2.1Introduction
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Section 2.2Analog and Digital Signal
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Sampling TheoremNyquist Theorem 23003400HzPSTN8000
0 1 level4 bit16quantizationquantization error
coding 0 1 PSTNPulse Code ModulationPCM82568KHz64,00064,000bps
Section 2.3Radio Transmission and Modeling
reflection diffraction scattering
Propagation Loss
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path lossslow fadingshadowingfast fading
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Okumura-Hata Model urban
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Section 2.4Modulation
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modulation(1/3)carriermodulating signalmodulated signal
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modulation(3/3)analog modulation & demodulation digital modulation & demodulation
Amplitude ModulationAM Frequency ModulationFMPhase ModulationPM
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Section 2.5Spreading Spectrum
Frequency Hopping Spread SpectrumFHSSDirect Sequence Spread SpectrumDSSS
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Section 2.6Channel Coding and Interleaving
channel codinginterleaving
error detectionerror correction block codingconvolution coding
GSM 260501327850 5313243787845620ms456bits/20 ms=22.8kbps
GSM GSM456857
Section 2.7Summary
Homework (1)- (8) 1, 3, 5, 7
After reading this chapter, the reader should be able to:Personal Communications ServicesPCSwireless communicationanytimeanywhereany terminalPCS networktelecommunication industrycomputer industry
Source coding , sampling, quantization, coding.Analog data: , ; discrete, . Audio analog data, , digital data , :0. Filter , .1. Sampling : . Ex: 4kHz , 8kHz ( 0.125 ms). samples, .2. Quantization : sampling , , . 6 bits , 0-63 , 29.2, 29 .3. Coding : ( code) binary pattern , 25 binary number 011001. 4. .Telephone voice is sampled: 8 bits, 8K times/secFor a HIFI orchestra recording, use more bits per sample, and more frequent samples.
sampling, (periodically) , . , sampling rate. Nyquist sampling theorem . 300-3800 Hz , 8kHz . () . 4kHz , 8kHz , , full voice (), , . sampling , ., ., input. 3 bits , (-4,4) ., zero , midrise (=0, 1 -1) . step size , uniform quantization. (), 1.3, 2 (=101) . 0.7 quantization noise granular error (). 5.3, 4 (=111) . 1.3 overload error (). sample bit , . quantization .Quantization noise : Quantization noise , . Ex: 1.8 error 0.2 3.8 .Quantization noise (or Signal-to-noise ratio) talker .
unique .fcGSMfc900MHzDPSK IS-95CDMA2000UMTSIS-951.2288MHz
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