Overview
Module 3 introduces various forms of data modulation and reception. We consider how performance varies across these various choices, both power efficiency and spectral efficiency. We also touch on the aspects of detection that increase the cost/complexity of various modulations. PartA of module 3 defines PSK, FSK, PAM and QAM modulation. We cover coherent detection for all cases, and noncoherent detection for DBPSK and M-FSK. We develop detection strategies and the receiver structures for different modulation formats.
Videos
Course notes
Objectives
- know MPSK, MFSK, PAM, QAM modulation and their signal space representation
- know the difference between baseband and passband (carrier) modulation
- interpret signal space to understand scaling properties of M-ary signaling
- be able to de normalize signal space coordinates and calculate minimal distance
- know the concept of orthogonal modulation and how to recognize orthogonal modulation
- know receiver architectures and explain the reason for their form
- be able to de find decision boundaries for a given constellation
- know the union bound to approximate the symbol error rate
Reading
- section 4.2 Digital Bandpass Modulation Techniques
- section 4.3 Detection of Signals in Gaussian Noise
- section 4.4 Coherent Detection
- section 4.7.1 Probability of Bit Error for Coherently Detected BPSK
- section 4.7.3 Probability of Bit Error for Coherently Detected Binary Orthogonal FSK
- section 4.8 M-ary Signaling and Performance
- section 4.9 Symbol Error Performance for M-ary Systems (M > 2)
- section 9.8.3 Quadrature Amplitude Modulation
- section 9.9.1 Commercial Telephone Modems
- section 9.9.2 Signal Constellation Boundaries
- section 9.9.3 Higher-Dimensional Signal Constellations
Overview
Module 3 introduces various forms of data modulation and reception. We consider how performance varies across these various choices, both power efficiency and spectral efficiency. We also touch on the aspects of detection that increase the cost/complexity of various modulations. PartB of Module 3 develops an equation for the probability of error for coherent detection of an arbitrary constellation, and applies that equation to various modulation formats. We introduce non-coherent detection for DBPSK and M-FSK, and quantify their probability of error.
Videos
Course notes
Objectives
- be able to apply the equations of symbol error rate for squared MPSK, MFSK and QAM
- be able to de find decision boundaries for a given constellation
- be able to apply the union bound to approximate the symbol error rate
- be able to find the SNR penalty vis-à-vis QPSK for a QAM, MPSK and MFSK modulation
- be able to find the SNR penalty vis-à-vis QPSK for a given constellation
- understand the motivation for noncoherent detection
- understand how to make use of the DPSK - appropriate conditions of use, forms for transmitter and for noncoherent receiver, performance
- understand the receiver architecture for noncoherent MFSK and its performance
- appreciate the form of non gaussian noise for noncoherent detection
Reading
- section 4.7.1 Probability of Bit Error for Coherently Detected BPSK
- section 4.7.3 Probability of Bit Error for Coherently Detected Binary Orthogonal FSK
- section 4.8 M-ary Signaling and Performance
- section 4.9 Symbol Error Performance for M-ary Systems (M > 2)
- section 9.8.3 Quadrature Amplitude Modulation
- section 9.9.1 Commercial Telephone Modems
- section 9.9.2 Signal Constellation Boundaries
- section 9.9.3 Higher-Dimensional Signal Constellations
- section 4.5 Noncoherent Detection
- section 4.7.4 Probability of Bit Error for Noncoherently Detected Binary Orthogonal FSK
- section 4.7.5 Probability of Bit Error for Binary DPSK
- section 4.7.6 Comparison of Bit Error Performance for Various Modulation Types
- section 4.9.4 Bit Error Probability versus Symbol Error Probability for Multiple Phase Signaling
Overview
Module 3 introduces various forms of data modulation and reception. We consider how performance varies across these various choices, both power efficiency and spectral efficiency. We also touch on the aspects of detection that increase the cost/complexity of various modulations. PartC of Module 3 develops the concept of spectral efficiency and how it can be quantified for various modulation formats. We discuss trade-offs between spectral and power efficiency, and introduce the concept of channel capacity. We clarify the difference between probability of bit error and symbol error, as well as the difference between SNR and Eb/N0.
Videos
- Bit vs. Symbol Error Probability (BER vs. SER) for Orthogonal Modulation
- Bit vs. Symbol Error Probability for Nonorthogonal Modulation w/ Grey Coding
- Minimum Frequency Spacing for MFSK
- Spectral Efficiency for MFSK
- Spectral Efficiency of MPSK and MQAM
- Contrasting MFSK vs. MPSK vs. MQAM for spectral and power efficiency
- SNR vs. Eb/N0
- Channel Capacity aka Shannon's Law
- Spectral Efficiency Plane
Course notes
Objectives
- understand the source of the minimum separation for carrier frequencies for M-FSK modulation
- know definition of spectral efficiency
- know the spectral efficiency of coherent and noncoherent M-FSK
- know the spectral efficiency of coherent MPSK and MQAM
- understand the trade-offs of spectral efficiency and performance for MFSK, MPSK, and MQAM
- understand the difference between the classic signal-to-noise ratio and Eb/N0
- understand how to interpret and generate the spectral efficiency plane
- understand the definition of channel capacity
- know Shannon's law for channel capacity
- understand the asymptotic limits of channel capacity
- understand the difference between the probability of symbol error and bit error
- understand the relationship between probability of symbol error and bit error for orthogonal and non-orthogonal modulation
- understand the importance of Grey coding and how to identify a Grey code
Reading
- section 9.7 Defining, Designing, and Evaluating Digital Communication Systems
- section 3.1.4 The Basic SNR Parameter for Digital Communication Systems
- section 9.4.1 Shannon Limit
- section 9.5 Bandwidth-Efficiency Plane
- section 4.9.3 Bit Error Probability versus Symbol Error Probability for Orthogonal Signals
- section 4.9.4 Bit Error Probability versus Symbol Error Probability for Multiple Phase Signaling
- section 9.7.5 Bandwidth-Limited Uncoded System Example