What's the difference between latency and delay?

Discussion in 'English Only' started by xxgeneral, Oct 9, 2010.

  1. xxgeneral New Member

    In the articles or newspapers, "latency or delay" accasionally comes up.
    What is the difference between them?
    Hope for opinions.
    Thanks a lot.
  2. Loob

    Loob Senior Member

    English UK
    Xxg, can you please give us at least one of the sentences in which you found this phrase?

    I can't, for the life of me, imagine any situation in I'd write "latency or delay":(.
  3. panjandrum

    panjandrum Occasional Moderator

    Belfast, Ireland
    English-Ireland (top end)
    This is really a technical question that needs to be answered by specialists in the relevant topic area.
    Commmunications scientists and physiologists, for example, may well have different views.
  4. sdgraham

    sdgraham Senior Member

    Oregon, USA
    USA English
    Yes, context, please.

    There's a huge difference, for example, between latent fingerprints and the time between when the head of a computer disk drive receives a signal and the when it actually reads the data from the disk (a common usage).
  5. xxgeneral New Member

    Thank you, guys.

    Here is the original paragraph:
    "QoS Metrics — QoS metrics include bandwidth, latency or delay, and packet-loss ratio. Depending on the application, these metrics or their variants could be used for WSNs. For example, sensor nodes may be used to transmit continuous images for target tracking. These nodes generate high-speed data streams and require higher bandwidth than most event-based applications. For a delay-sensitive application, WSNs may also require timely delivery data."

    I have searched in Wikipedia, but still can't get the difference.
  6. Majorbloodnock Senior Member

    South East England
    British English
    In general, when talking about networks, I would use latency as the word to describe the time between data being sent and the same data being received. I would talk about delays if there was a hold-up in the data being sent in the first place. Therefore, you could have a delay in data being sent, then clock up more time because of the latency of the network itself.
  7. ABBA Stanza Senior Member

    Hessen, DE
    English (UK)
    In the hardware business in general, "latency" basically means "inherent delay" (i.e., the delay caused by the underlying technology being used).

    By contrast, "delays" are due to other hold ups (e.g., packet processing, queuing due to network congestion, or retransmission of data due to packet loss). In networking terms, such delays can be incurred on every router on the network path being taken by the data.

    I hope that's accurate enough for your purposes. Unfortunately, since this is a language forum, and not a technical one, I don't think we can go into more detail on this topic. :(

  8. panjandrum

    panjandrum Occasional Moderator

    Belfast, Ireland
    English-Ireland (top end)
    From the way this sentence is expressed I think the writer is suggesting that in his view latency and delay are the same. Otherwise he would have written "... include bandwidth, latency, delay and packet-loss ratio."

    Searching around, you will find various attempts to distinguish one from the other, but no clear resolution. Where each is defined, there seems to be no consistency of definition.

    So in any particular context, I would not assume any definition of either, and in this particular context it doesn't matter at all whether there is any difference.
  9. xxgeneral New Member

    Thank all of you very much, guys.
    Thanks for your help.
  10. emeryp3 New Member

    English - U.S.A.
    As I understand it and outside of computer speak, latency is when something exists but is underdeveloped or not developped at all. A delay is more start forward. One could say that the train is late because of a delay caused by an accident. The train could experience latency because the workers building the track were on strike.

    I hope this helps.

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