I'm new to EE, just a question on bandwidth in a channel. The book I'm reading describe the definition of bandwidth as

The term bandwidth can refer to the number of bits per second that a channel, a link, or even a network can transmit.

Below is a picture to illustrate: enter image description here

Below are my questions:

  1. Since bandwidth refer to the number of bits per second that a channel can transmit. So in the picture, the channel/link can move/transmit 5 bits in one second(inside the channel/link), shouldn't the bandwidth be 5bps?

  2. If "transmit" means how many bits the receiver receives in one second, then it make senses that the bandwidth is 1bps, but it also raises another question, the bandwidth is 0bps for the receiver in the first five seconds(since the first bit hasn't reached the receiver's end), after 5 secs, the bandwidth is 1bps. So strictly speaking, the receivers has no bandwidth in the first 5 secs, but since we are talking bandwidth in a broad picture, the initial no bandwidth state can be ignored, is my understanding correct?

  • \$\begingroup\$ If I have a 5 gallon bucket, but I only put 1 gallon of water in it, it's still a 5 gallon bucket. \$\endgroup\$
    – The Photon
    Oct 11, 2019 at 0:24
  • \$\begingroup\$ Instead consider the analog definition of bandwidth which is how badly higher frequencies attenuated as they pass through the channel. Then consider how higher digital data rates means faster edges which means higher frequency components (Fourier) which means more analog bandwidth required for faster digital transmission. The concept of digital bandwidth is just shorthand for all this. \$\endgroup\$
    – DKNguyen
    Oct 11, 2019 at 1:35
  • \$\begingroup\$ The word you are looking for re the second point is latency. The channel has 1bps bamdwidth and 5 seconds latency. \$\endgroup\$
    – user16324
    Oct 11, 2019 at 7:43

1 Answer 1

  1. No, you're still only putting 1 bit per second and getting 1 bit per second at the other end. The fact that the channel is "storing" 5 bits is irrelevant.

  2. Bandwidth is the maximum channel capacity, not the actual number of bits transferred at any given moment.

  • \$\begingroup\$ In addition to bandwidth, the maximum channel capacity also depends on the signal-to-noise ratio at the decoder. \$\endgroup\$ Apr 23, 2021 at 22:58

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