S MandayamECE Dept Rowan University Digital Communications 0909

S. Mandayam/ECE Dept. /Rowan University Digital Communications 0909. 402. 03/0909. 504. 01 Fall 2002 Lecture 1 September 9, 2002 Shreekanth Mandayam ECE Department Rowan University http: //engineering. rowan. edu/~shreek/fall 02/digcomm/

S. Mandayam/ECE Dept. /Rowan University Plan • Introduction Digital Communications • Evolution • Rationale • Course Logistics • Review of ECOMMS • • Signals Systems Digital Communications Transceiver (CODEC/MODEM) Principles • Introduction to Lab

S. Mandayam/ECE Dept. /Rowan University Digital Communications • Some Milestones • • • Claude Shannon, 1948 X. 25 (Telephony) IEEE 802. 3 (Ethernet) ARPANET, 1969 IEEE 802. 5 (FDDI) ISO-OSI 7 -layer Network Reference Model CDMA GSM VOIP • SIP protocols. com

S. Mandayam/ECE Dept. /Rowan University Wireless Comm Evolution/Revolution: UMTS (3 G) http: //www. 3 g-generation. com/ http: //www. nttdocomo. com/reports/010902_ir_presentation_january. pdf

S. Mandayam/ECE Dept. /Rowan University TECHNOLOGY 1 -G Evolution Late 1970’s, early 1980’s 2 -G 1990’s 3 -G 2000 and beyond FEATURES AMPS Advanced Mobile Phone Service -Analog voice service - No data service CDMA Code Division Multiple Access TDMA Time Division Multiple Access GSM Global System for Mobile Communications PDC Personal digital cellular Digital voice service - 9. 6 K to 14. 4 K bit/sec. - CDMA, TDMA and PDC offer one-way data transmissions only - Enhanced calling features like caller ID - No always-on data connection W-CDMA Wide-band Code Division Multiple Access CDMA-2000 Based on the Interim Standard-95 CDMA standard TD-SCDMA Time-division synchronous CDMA - Superior voice quality - Up to 2 M bit/sec. always -on data - Broadband data services like video and multimedia - Enhanced roaming

S. Mandayam/ECE Dept. /Rowan University And there’s more…. Joseph M. Nowack, http: //www. jacksons. net/~tac/

S. Mandayam/ECE Dept. /Rowan University Digital Communications: Rationale • Information Theory: • What is the fundamental limit on the compression and refinement of information generated by the source? • What is the fundamental limit on the transmission rate of information over a noisy channel? • How do we approach these limits?

S. Mandayam/ECE Dept. /Rowan University Digital Communications • Please read these!!!! • Digital Modulation in Communications Systems: An Introduction, Hewlett-Packard Application Note 1298 http: //www. tm. agilent. com/tmo/Notes/pdf/5965 -7160 E. pdf Mirrored at: http: //engineering. rowan. edu/~shreek/spring 00/ecomms/notes/ 5965 -7160 E. pdf • Source Basics, Agilent Technologies Teachers Tools Slide Presentation http: //www. educatorscorner. com/tools/lectures/slides/srcbas. html Mirrored at: http: //engineering. rowan. edu/~shreek/spring 00/ecomms/notes/ scrbas. ppt

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

S. Mandayam/ECE Dept. /Rowan University Course Logistics http: //engineering. rowan. edu/~shreek/fall 02/digcomm/

S. Mandayam/ECE Dept. /Rowan University ECOMMS http: //engineeri ng. rowan. edu/~ shreek/spring 02 /ecomms/

S. Mandayam/ECE Dept. /Rowan University What is a communications system? • Communications Systems: Systems designed to transmit and receive information Info Source Comm System Info Sink

S. Mandayam/ECE Dept. /Rowan University Info Source m(t) message from source Block Diagram Transmitter Channel Tx s(t) transmitted signal Receiver Rx r(t) received signal received message to sink Info Sink

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

S. Mandayam/ECE Dept. /Rowan University Digital Modulation Carrier signal: Ac cos (2 pfct + f) Modulation: Modulated signal: m(t) Ac (t) cos (2 pfc(t) t + f(t)) Vary amplitude Vary frequency Vary phase Variations are discrete!!!!! m(t); discrete

S. Mandayam/ECE Dept. /Rowan University Principle 1 0……… Digital code Analog message 1 AM FM PM AM & PM 0 1 Digital message 1 1 0 0 modulate 0 Sinusoidal carrier

S. Mandayam/ECE Dept. /Rowan University Signal Vector Representation s(t) = Ac(t) cos (2 pfct + f(t)) fixed!!! Q M a gn e d itu S Phase I I-Q Plane 0 degrees

S. Mandayam/ECE Dept. /Rowan University Signal Changes: Representation in the IQ Plane Magnitude Change Q Q S 1 S 2 I Magnitude & Phase Q Change I-Q Diagrams or Constellations S 1 S 2 I Phase S 2 Change S 1 I Frequency Change ? ? ?

S. Mandayam/ECE Dept. /Rowan University Quadrature Phase Shift Keying (QPSK) IQ Diagram s(t) = Ac cos(2 pfct + f(t)) Q f(t) 3 p/4 01 p/4 00 -p/4 -3 p/4 10 11 11 10 p/4 t 01 I 00

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

S. Mandayam/ECE Dept. /Rowan University Laboratory Software • • • Matlab & Simulink DSP Toolbox DSP Blockset Communications Toolbox Communications Blockset

S. Mandayam/ECE Dept. /Rowan University Summary