Wireless Communication presents about geometric representation of modulation signals; linear modulation; constant envelope modulation; combined linear and constant envelope modulation (MPSK, QAM, MFSK and OFDM). | EE 6332, Spring, 2014 Wireless Communication Zhu Han Department of Electrical and Computer Engineering Class 12 Feb. 24nd, 2014 Outline (Chapter ) Geometric representation of modulation signals Linear modulation BPSK, DPSK; QPSK, offset QPSK, /4 QPSK Constant envelope modulation BFSK, MSK, GMSK Combined linear and constant envelope modulation MPSK QAM MFSK and OFDM Analog Modulation: PAM, PWM, PPM, PCM Geometric Representation of Modulation Signal Digital Modulation involves Choosing a particular signal waveform for transmission for a particular symbol or signal For M possible signals, the set of all signal waveforms are: For binary modulation, each bit is mapped to a signal from a set of signal set S that has two signals We can view the elements of S as points in vector space Geometric Representation of Modulation Signal Vector space We can represented the elements of S as linear combination of basis signals. The number of basis signals are the dimension of the vector space. Basis signals are orthogonal to each-other. Each basis is normalized to have unit energy: Example Q I The basis signal Two signal waveforms to be used for transmission Constellation Diagram Dimension = 1 Constellation Diagram Properties of Modulation Scheme can be inferred from Constellation Diagram Bandwidth occupied by the modulation increases as the dimension of the modulated signal increases Bandwidth occupied by the modulation decreases as the signal points per dimension increases (getting more dense) Probability of bit error is proportional to the distance between the closest points in the constellation. Bit error decreases as the distance increases (sparse). Concept of a constellation diagram Example of samples of matched filter output for some bandpass modulation schemes Linear Modulation Techniques Classify digital modulation techniques as: Linear The amplitude of . | EE 6332, Spring, 2014 Wireless Communication Zhu Han Department of Electrical and Computer Engineering Class 12 Feb. 24nd, 2014 Outline (Chapter ) Geometric representation of modulation signals Linear modulation BPSK, DPSK; QPSK, offset QPSK, /4 QPSK Constant envelope modulation BFSK, MSK, GMSK Combined linear and constant envelope modulation MPSK QAM MFSK and OFDM Analog Modulation: PAM, PWM, PPM, PCM Geometric Representation of Modulation Signal Digital Modulation involves Choosing a particular signal waveform for transmission for a particular symbol or signal For M possible signals, the set of all signal waveforms are: For binary modulation, each bit is mapped to a signal from a set of signal set S that has two signals We can view the elements of S as points in vector space Geometric Representation of Modulation Signal Vector space We can represented the elements of S as linear combination of .
