mobile communication

2. Advanced Frequency Shift Keying If Even and Odd bits are both zero : - f2 is inverted. If Even bit is 1 and odd bit is zero: - Lower frequency f1 is inverted. If Even bit is zero and the odd bit is 1: - f1 is taken without phase change, as is. If Both even and odd bits are 1 : - frequency f2 is taken as is.

3. Example of MSK data even bits odd bits 1 1 1 1 0 0 0 t low frequency high frequency MSK signal bit even 0 1 0 1 odd 0 0 1 1 signal h n n h value - - + + h: high frequency n: low frequency +: original signal -: inverted signal No phase shifts!

10. Spreading and Despreading – Resistance to narrow band interference dP/df f i) dP/df f ii) sender dP/df f iii) dP/df f iv) receiver f v) user signal broadband interference narrowband interference dP/df

12. Spreading and frequency selective fading frequency channel quality 1 2 3 4 5 6 narrow band signal guard space narrowband channels spread spectrum channels

14. How to fix the narrow band interference problem? 2 2 2 2 2 frequency channel quality 1 spread spectrum

22. DSSS (Direct Sequence Spread Spectrum) II X user data chipping sequence modulator radio carrier spread spectrum signal transmit signal transmitter demodulator received signal radio carrier X chipping sequence lowpass filtered signal receiver integrator products decision data sampled sums correlator

24. FHSS (Frequency Hopping Spread Spectrum) I user data slow hopping (3 bits/hop) fast hopping (3 hops/bit) 0 1 t b 0 1 1 t f f 1 f 2 f 3 t t d f f 1 f 2 f 3 t t d t b : bit period t d : dwell time

27. FHSS Transmitter and Receiver modulator user data hopping sequence modulator narrowband signal spread transmit signal transmitter received signal receiver demodulator data frequency synthesizer hopping sequence demodulator frequency synthesizer narrowband signal

28. SPECTRAL ANALYSIS

33. Frequency planning II f 4 f 5 f 1 f 3 f 2 f 6 f 7 f 3 f 2 f 4 f 5 f 1 f 3 f 5 f 6 f 7 f 2 f 2 3 cell cluster 7 cell cluster 3 cell cluster with 3 sector antennas f 1 f 2 f 3 f 2 f 1 f 1 f 2 f 3 f 2 f 3 f 1 f 2 f 1 f 3 f 3 f 3 f 3 f 3 f 1 f 1 f 1 f 2 f 3 f 2 f 3 f 2 f 3 h 1 h 2 h 3 g 1 g 2 g 3 h 1 h 2 h 3 g 1 g 2 g 3 g 1 g 2 g 3

37. Cell Coverage