Digital Communication I

Lecturer: Dr I.M. Leslie (iml@cl.cam.ac.uk)

No. of lectures: 12  

Scope.

Two example systems: Ethernet and the telephone system: basic operation; common issues; differing constraints; differing approaches.

Partitioning the problem.

Abstraction, service versus implementation; layering as a restricted form of abstraction; motivation for layering; the channel as an abstraction; layered channels.

Fundamental transmission.

Emphasis on the service provided by physical channel; limitations: noise, attenuation. Channel capacity (bandwidth). Modulation techniques for digital systems.

Coding.

Coding as a general concept: modulation as a form of coding, A-D-D-A, error correcting and detecting codes, other forms of coding, relation to layering.

Multiplexing.

Basic definitions, FDM, synchronous and asynchronous TDM. Circuit switching, packet switching, ATM. Local area networks with particular emphasis on media access control.

Switching and routing.

Introduction from LAN perspective (repeaters, bridges, routers). Fundamental view of switching extended to telephone network, connectionless versus connection oriented.

Naming, addressing and routing.

Service access points, binding. Hierarchical versus flat address spaces. Routing classifications and algorithms.

Protocols and state.

Imperfect view of state at far end of channel. ARQ as an example of an error control protocol; sliding window ARQ as an example of a flow control protocol; flow control in general: X.25 as an example.

Standards.

Role of standards, dynamics of standards process, standards bodies.

Recommended books:

Comer, D. & Stevens, D. (1995). Internetworking with TCP-IP, vol. 1 and 2. Prentice-Hall (3rd ed.).

Halsall, F. (1992). Data Communications, Computer Networks and Open Systems. Addison-Wesley (3rd ed.).

Schwartz, M. (1987). Telecommunication Networks: Protocols, Modeling and Analysis. Addison-Wesley.