S. Mandayam/ ECOMMS/ECE Dept./Rowan University Electrical Communications Systems ECE Spring 2010 Shreekanth Mandayam ECE Department Rowan University Lecture 12b April 14, 2010

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Plan Digital Bandpass Communications Quadrature Phase Shift Keying (QPSK) M-ary PSK and M-ary QAM Observing Digital Bandpass Signals Constellation diagrams Eye Diagrams Data Processing & Data Communications Communications Networks Packet Switched Networks OSI 7-Layer Protocol Architecture TCP-IP Protocol Architecture

S. Mandayam/ ECOMMS/ECE Dept./Rowan University ECOMMS: Topics

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Digital Communications Transceiver Anti- aliasing Filter Data Encryption Encoder Source Encoder Error Control Encoder Channel/ Line Encoder Modulator MUX Audio Amp Source Decoder Data Encryption Decoder Error Control Decoder Equalization / Decision Circuits Demod- ulator DEMUX Reconstruction/ DAC ADC CODEC MODEM Analog o/p Multiple access channel Analog i/p Sampling Quantization

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Quadrature Phase Shift Keying (QPSK) I Q 11 IQ Diagram s(t) = A c cos(2  f c t +  (t)) t  (t)     

S. Mandayam/ ECOMMS/ECE Dept./Rowan University M-ary Phase Shift Keying (M-ary PSK) I Q Octophase I-Q Constellation

S. Mandayam/ ECOMMS/ECE Dept./Rowan University M-ary Quadrature Amplitude Modulation (M-ary-QAM) I Q 16 QAM I-Q Constellation

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Different ways of looking at a digitally modulated signal

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Time & Frequency Domain View Reproduced from:

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Frequency & Power View Reproduced from:

S. Mandayam/ ECOMMS/ECE Dept./Rowan University I-Q Constellation Diagram Reproduced from: Matlab Demo: qpsk.m

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Eye Diagram Reproduced from: Matlab: >>eyediagram

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Digital Communications Transceiver Anti- aliasing Filter Data Encryption Encoder Source Encoder Error Control Encoder Channel/ Line Encoder Modulator MUX Audio Amp Source Decoder Data Encryption Decoder Error Control Decoder Equalization / Decision Circuits Demod- ulator DEMUX Reconstruction/ DAC ADC CODEC MODEM Analog o/p Multiple access channel Analog i/p Sampling Quantization

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Digital Communication Paradigms Multiplexer Message 2 Message 3 Message S S Demultiplexer Message 2 Message 3 Message 1 Packetizing Message 2 Message 3 Message 1 1H H 2 3 H H 2 1H 3 H H 2 1H 3 H Message 2 Message 3 Message 1 Depacket- izing Circuit Switching Packet Switching Sync bits Header bits Recall

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Communications Networking Router Step 1: Step 2: Step 3: …….. Protocol Sender Medium Step 1: Step 2: Step 3: …….. Protocol Receiver Message

S. Mandayam/ ECOMMS/ECE Dept./Rowan University A 3-Layer Protocol Architecture File transfer application Communications service module Network access module File transfer application Communications service module Network access module Computer 1 Computer 2 Comm network Files and file transfer commands Comm related messages

S. Mandayam/ ECOMMS/ECE Dept./Rowan University ISO OSI 7-Layer Model Physical Data Link Network Presentation Session Transport Application Please Do Not Touch Steve’s Pet Alligator

S. Mandayam/ ECOMMS/ECE Dept./Rowan University TCP-IP Protocol Architecture Physical Network Access Internet Transport (host-to-host) Application TCP-IP Application Presentation Session Transport Network Data Link Physical OSI Hardware Firmware Software Operating system User space

S. Mandayam/ ECOMMS/ECE Dept./Rowan University TCP-IP Operation Example Network access protocol #1 Physical IP TCP Host A App X App Y Network access protocol #2 Physical IP TCP Host B App X App Y Logical connection (TCP) Port or Service access point (SAP) Global network address Network 1 Network 2 IP NAP1NAP2 Router J Subnetwork attachment point address Logical connection

S. Mandayam/ ECOMMS/ECE Dept./Rowan University TCP-IP Protocol Packet TCP header IP header Network header User Data Application Byte Stream TCP Segment IP Datagram Network Level Packet

S. Mandayam/ ECOMMS/ECE Dept./Rowan University IP Header VersionIHLType of ServiceTotal Length IdentificationFlagsFragment Offset Time to LiveProtocolHeader Checksum Source Address Destination Address Options + Padding octets

S. Mandayam/ ECOMMS/ECE Dept./Rowan University TCP Header Source PortDestination Port Sequence Number Acknowledgement Number Data OffsetReserved URGURG ACKACK PSHPSH RSTRST SYNSYN FINFIN Window ChecksumUrgent Pointer Options + Padding octets

S. Mandayam/ ECOMMS/ECE Dept./Rowan UniversitySummary