1. Professor Andrea Goldsmith
EE 179: Introduction to Communications
Professor Andrea Goldsmith

2. Outline Course Information and Policies Communication Systems Today
Future Systems
Design Challenges

3. Course Information (see web or handout for more details)
Instructor: Andrea Goldsmith, Packard 371, Ext: 56932, OHs: M 1-2pm, W 12-1pm, Th 5:30-6:30.
Class Homepage: (temporary page at
TAs:
Neil OHs and OHs: TBD
Ragiv Agrawal, OHs and OHs: TBD
Class mailing list: ee179-students (automatic for registered students), ee179-staff for instructor/TAs, guest list available
Discussion Section: T 6-7pm (tentative)
Book: An Introduction to Analog and Digital Communications
Grading: HWs 30%, Midterm 30%, Final 40%
Prerequisites: EE102a or equivalent

4. Class Policies Exam policy: HW policy:
Exams must be taken at their scheduled times.
Exceptions only in very rare circumstances.
Midterm: 2/13 from 11-12:30pm
Final: 3/18 from 8:30-11:30am.
HW policy:
Assigned Wednesday, due following Thursday. Lose 25% credit per day late.
Up to 3 students can collaborate on 1 writeup. All collaborators must work out all problems.

5. Communication Systems
Provide for electronic exchange of multimedia data
Voice, data, video, music, , web pages, etc.
Communication Systems Today
Radio and TV broadcasting (covered later in the course)
Public Switched Telephone Network (voice,fax,modem)
Cellular Phones
Computer networks (LANs, WANs, and the Internet)
Satellite systems (pagers, voice/data, movie broadcasts)
Bluetooth

6. PSTN Design Local exchange Circuit switched network tailored for voice
Local Switching
Office (Exchange)
Local Switching
Office (Exchange)
Long Distance Lines
(Fiber)
Fax
Modem
Local Line
(Twisted Pair)
Local exchange
Handles local calls
Routes long distance calls over high-speed lines
Circuit switched network tailored for voice
Faxes and modems modulate data for voice channel
DSL uses advanced modulation to get 1.5 Mbps

7. Cellular System Basics
Geographic region divided into cells
Frequencies/timeslots/codes reused at spatially-separated locations (analog systems use FD, digital use TD or CD)
Co-channel interference between same color cells.
Handoff and control coordinated through cell base stations
BASE
STATION

8. Cell Phone Backbone Network
San Francisco BS BS
New York
MTSO
MTSO
PSTN BS
Internet

9. Local Area Networks (LANs)
1011
0101
0101
1011
LANs connect “local” computers
Breaks data into packets
Packet switching (no dedicated channels)
Proprietary protocols (access,routing, etc.)

10. Wireless Local Area Networks (WLANs)
1011
0101
Internet
Access
Point
WLANs connect “local” computers (100m range)
Breaks data into packets
Channel access is shared (random access)
Backbone Internet provides best-effort service

11. Wide Area Networks: The Internet
1011
LAN
Bridge
MAN
Bridge
LAN
0101
Satellite and
Fiber Lines
Many LANs and MANs bridged together
Universal protocol: TCP/IP (packet based).
Guaranteed rates or delays cannot be provided.
Hard to support user mobility.
Highly scalable and flexible topology
Local: 100m range
For efficiency and fairness, data is packetized.
Packet routing: packets may take different routes, may entail delays on some routes, lost packets, packets arriving out of order (bad for video).
Mobility hard to support due to underlying routing and addressing protocols
Optimized for stationary data users, in contrast to cellular networks optimized for mobile voice users.
- How will these networks support multiple applications (voice, data, video, and whatever else comes down the pike?)

12. Satellite Systems Cover very large areas Different orbit heights
GEOs (39000 Km) versus LEOs (2000 Km)
Optimized for one-way transmission
Radio (XM, DAB) and movie (SatTV) broadcasting
Most two-way systems struggling or bankrupt
Expensive alternative to terrestrial system
A few ambitious systems on the horizon

13. Paging Systems Broad coverage for short messaging
Message broadcast from all base stations
Simple terminals
Optimized for 1-way transmission
Answer-back hard
Overtaken by cellular

14. Bluetooth Cable replacement for electronic devices
Cell phones, laptops, PDAs, etc.
Short range connection ( m)
1 data (721 Kbps) and 3 voice (56 Kbps) channels
Rudimentary networking capabilities

15. Future Systems Ubiquitous Communication Among People and Devices
Nth Generation Cellular
Nth Generation WLANs
Nth Generation Internet
Wireless Entertainment
Sensor Networks
Smart Homes/Appliances
Automated Cars/Factories
Telemedicine/Learning
All this and more…

16. Ad-Hoc Networks Peer-to-peer communications.
No backbone infrastructure.
Routing can be multihop.
Network topology is dynamic.
-No backbone: nodes must self-configure into a network.
-In principle all nodes can communicate with all other nodes, but multihop routing can reduce the interference associated with direct transmission.
-Topology dynamic since nodes move around and link characteristics change.
-Applications: appliances and entertainment units in the home, community networks that bypass the Internet. Military networks for robust flexible easily-deployed network (every soldier is a node).

17. Sensor Networks Energy is the driving constraint
Nodes powered by nonrechargeable batteries
Data flows to centralized location.
Low per-node rates but up to 100,000 nodes.
Data highly correlated in time and space.
Nodes can cooperate in transmission, reception, compression, and signal processing.

18. Distributed Control over Wireless Links
Automated Vehicles
- Cars
- UAVs
- Insect flyers
Packet loss and/or delays impacts controller performance.
Controller design should be robust to network faults.
Joint application and communication network design.

19. Design Challenges Hardware Design System Design Network Design
Precise components
Small, lightweight, low power
Cheap
High frequency operation
System Design
Converting and transferring information
High data rates
Robust to noise and interference
Supports many users
Network Design
Connectivity and high speed
Energy and delay constraints

20. Main Points
Communication systems send information electronically over communication channels
Many different types of systems which convey many different types of information
Design challenges include hardware, system, and network issues
Communication systems recreate transmitted information at receiver with high fidelity
Focus of this class is design and performance of analog and digital communication systems