network-programmingswitchingtransmission

Calculating the transmission rate in a circuit-switched network with time-division multiplexing

This is a quote from the 8th Global Edition of Computer Networking: A Top-Down Approach:

For TDM, the transmission rate of a circuit is equal to the frame rate multiplied by the number of bits in a slot. For example, if the link transmits 8,000 frames per second and each slot consists of 8 bits, then the transmission rate of each circuit is 64 kbps.

Doing what the book says — multiplying 8 bits with 8,000 frames per second — I calculate the transmission rate to be 64,000 bits per second, which is 8 kbps not 64.

Am I wrong or is it the book?

Solution

  • You're correct and the book is wrong. It seems the book mixed up bits with bytes.

    If it was that a slot consists of 8 bytes then 64,000 bytes = 64 kbps.

    However, you are correct that 64,000 bits = 8 kbps.