Digital Modulation Techniques in Mobile Communications

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Gaussian Minimum Shift KeyingGMSKEven though MSK's power spectrum density falls quite fast, it does not fall fastenough so that interference between adjacent signals in the frequency bandcan be avoided. To take care of the problem, the original binary signal ispassed through a Gaussian shaped filter before it is modulated with MSK.Frequency Response:The principle parameter in designing an appropriate Gaussian filter is the timebandwidthproduct WTb. Please see the following figure for the frequencyresponse of different Gaussian filters. Note that MSK has a time-bandwidth productof infinity.Fahredd'n Sadikoglu 36
As can be seen from above, GMSKs power spectrum drops much quickerthan MSK's. Furthermore, as WTb is decreased, the roll-off is much quicker.
Page 1 and 2: Digital Modulation Techniques inMob
Page 3 and 4: Modulation Techniques• Modulation
Page 5 and 6: Amplitude Shift Keying (ASK)- Pulse
Page 7 and 8: Phase Shift Keying (PSK)- Binary Ph
Page 9 and 10: Multi-PhaseBinary Phase ShiftKeying
Page 11 and 12: Quadrature Phase-Shift Keying(QPSK)
Page 13 and 14: QPSKModeled as two BPSK systems inp
Page 15 and 16: QPSK TYPESFahredd'n Sadikoglu 15
Page 17 and 18: Fahredd'n Sadikoglu 17
Page 19 and 20: OQPSKBit transitions occur every T
Page 21 and 22: OPSKFahredd'n Sadikoglu 21
Page 23 and 24: QPSK & OQPSK0 1 1 1 0 0 0 1(-1, 1)(
Page 25 and 26: π/4-QPSKDual constellation diagram
Page 27 and 28: Minimum Shift Keying (MSK)• It is
Page 29 and 30: MSKMSK uses changes in phase to rep
Page 31 and 32: ● If it assumed that h = 1/2, the
Page 33 and 34: MSK better than QPSKEven though the
Page 35: MSKFahredd'n Sadikoglu 35
Page 43 and 44: The figure shows the 16-bit NRZ (No
Page 45 and 46: • The figure shows the MSK and GM
Page 47 and 48: (5)Frequency offset:* This refers t
Page 49 and 50: How to implement a GMSK modulator?F
Page 51 and 52: GSM Modulation SpecificationsIn the

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