Homework 5: Due October 12

• What is multiplexing? What is the economic rationale for its use?

• What is frequency division multiplexing?

• How does statistical TDM differ from synchronous TDM?

• Three terminals A, B, and C are to be connected to three computers D, E and F so that A is connected D, B to E and C to F. All are in different cities. A and D are 1500 miles apart as are B and E and C and F. The locations of the terminals are 25 miles apart (i.e., A is 25 miles from B and C and B is 25 miles from C). The same is true for the locations of the computers D, E and F.

• If telephone lines cost \$1 per mile, what is the line cost for three independent lines?

• If a multiplexer/demultiplexer pair costs \$2000, can you save money by another arrangement of lines? If so, how much?

• Investigate the pricing structure of a T1 line from Pittsburgh to Philadelphia? How does it compare to a 56Kbps DDS line? Document your source.

• What is the cost of a 24 port multiplexer that can support 24 56/64Kbps channels on the user side? What is the cost of CSU/DSU that can be used with 56Kbps service? Document your source.

• Given your investigation of costs of T1 and 56Kbps service, under what conditions would you recommend multiplexing?

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Ramayya Krishnan rk2x@andrew.cmu.edu