CDMA 120 – cdmaOne and CDMA2000 Concepts and Terminology phần 2 pptx

[...]... the phases are: 45, 135, 22 5, and 315 degrees All transitions are allowed including those through the origin (180°) © 20 02 QUALCOMM Incorporated 2- 24 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background I- Channel Input Data Q- Channel Input Data CDMA 120 OQPSK cdma university Section 2- 25 tb b1 b0 b2 b3 b4 tb a0 a1 a2 a3 MMT98010102Ag.emf Offset Quadrature... dBW = 10 log P 1W © 20 02 QUALCOMM Incorporated 2- 26 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background Analog and RF Concepts (continued) cdma university Watts dBw dBm 1,000,000 100.000 10,000 1,000 100 10 4 2 1 0.5 0 .25 0.1 0.01 0.001 0.0001 0.00001 0.000001 +60 +50 +40 +30 +20 +10 +6 +3 0 -3 -6 -10 -20 -30 -40 -50 -60 CDMA 120 Section 2- 27 +90 +80 +70 +60... -20 -30 -40 -50 -60 CDMA 120 Section 2- 27 +90 +80 +70 +60 +50 +40 +36 +33 +30 +27 +24 +20 +10 0 -10 -20 -30 MMT98010104Ag.emf Notes © 20 02 QUALCOMM Incorporated 2- 27 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background CDMA 120 Radio Channel Characteristics cdma university Section 2- 28 Signals may add 5V 0V -5V 5V 0V -5V MMT98010691Ag.emf Constructively MMT98010106Ag.emf... systems, including cdmaOne systems, commonly use Convolutional Coding to introduce redundancy and enable the receiver to correct some detection errors without increasing transmission power © 20 02 QUALCOMM Incorporated 2- 19 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background cdma university Spread Spectrum Techniques CDMA 120 Section 2- 20 C = W log 2( 1 + S/N) C =... hopping — more than one bit is hopped from one frequency to another © 20 02 QUALCOMM Incorporated 2- 22 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background CDMA 120 Binary Phase Shift Keying cdma university 1 Section 2- 23 1 0 Digital Signal BPSK -sinw ct (logic 0) sinw ct (logic 1) MMT98010 129 Ac.emf Binary Phase Shift Keying (BPSK) Binary phase shift keying is... last decade © 20 02 QUALCOMM Incorporated 2- 20 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background cdma university CDMA 120 Spread Spectrum Techniques (continued) Section 2- 21 BPSK or QPSK Modulator Data Spread fc PN Clock PN Generator Oscillator 1 .25 MHz fc MMT98010184Ag.emf Direct Sequence Spread Spectrum The information signal is inherently narrowband, on the... to transmission In cdmaOne systems, for example, a Traffic Channel data block (frame) is generated once every 20 milliseconds When transmitted at a rate of 14,400 bps, each frame contains 28 8 bits; twelve of these bits are CRC bits © 20 02 QUALCOMM Incorporated 2- 18 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background cdma university CDMA 120 Error Correction... down to about 4-13 kbps, depending on the technique used cdmaOne system vocoders average about 4-7 kbps © 20 02 QUALCOMM Incorporated 2- 17 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background CDMA 120 Error Detection Codes cdma university Block of data bits Section 2- 18 Additional check bits CRC Bits MMT98010 126 Ac.emf Cyclic Redundancy Checking (CRC) CRC provides... signal © 20 02 QUALCOMM Incorporated 2- 23 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background CDMA 120 QPSK cdma university Section 2- 24 10 00 11 01 MMT98010101Ag.emf Quadrature Phase Shift Keying (QPSK) QPSK is another form of constant-amplitude digital modulation The QPSK carrier cycles through four output phases The figure shows a QPSK transmitter and a QPSK... narrowband signal is spread over a much larger bandwidth by multiplying the information signal by a wideband spreading code Direct sequence spread spectrum is the technique used in cdmaOne systems How this spreading is accomplished is the topic of the next section © 20 02 QUALCOMM Incorporated 2- 21 CDMA 120 – cdmaOne and CDMA2 000 Concepts and Terminology 80-13 321 -1 X11 Section 2: Background cdma university