[MLB-WIRELESS] Transfer Rates

[Joe Hovel]

One of the biggest issues I find in a discussion like this is the "mixed
units confusion"  :)
People often talk about "Megs" or whatever without specifying (or sometimes
even knowing) the units they are talking about, eg. MB (mega bytes =
1024kilobytes), Mb (megabits), MHz (megahertz), Mbps (megabits per second)
or MBps (mega bytes per second). When the possible ranges are great enough,
such as in networking bandwidth, confusion can reign.
Cameron's suggestions are most helpful: he suggests NOT to talk about
throughput in terms of bits per second, but to use Bytes per second.
To put this in context, Michaels' explanation of overheads and latency
helped.
I suggest we use a little more "discipline" and put the "ps" at the end of
the unit to identify speed rather than volume when talking about transfer
performances and use "B" instead of "b" to refer to "Bytes" (=8+1+1or 0 bits
or = 7+1+1or2 bits) and "bits" (= binary digits = 1 or 0).
I'd be interested know in this context how big (in bits) each frame and
packet identifier is and how many are needed in each  - say - kilobit or
kilobyte of transmitted data.
We might then get a better idea of comparing apples with apples.... I get
around 350kbps sustained data rate on  my 802.11b 11Mbps network, using a
single AP and network client. MUCH lower than the 3+ Mbps of a wired 10Mbps
Ethernet link!
Cheers,
Joe

 -----Original Message-----
From: Rowan Wainwright-Smith [mailto:Rowan at teleaudit.com]
Sent: Tuesday, 17 September 2002 9:15
To: Cameron Donaghey
Subject: Re: [MLB-WIRELESS] Transfer Rates


    Cameron,

    transfer rates are a little tricky, 'coz there are two ways of
measureing them

    1    PURE Bandwidth - how many BITS per second!
    2.   Transfer performance (usually measured in BYTES per second)

    The stats you are getting are pretty reasonable, but you should be able
to get about 550(-600)k/sec


    these cards are 11 Mbit,

    if you work it out, you are getting about 2.5mbit transfer rate (not
counting TCP overheads) Bear in mind that these devices are 11mbit TOTAL
bandwidth, so if you have two PC's communicating, then you can really only
expect up to approx 5Mbit transfer, 3PC's then about 3.5 Mbit & so on.

    Wireless is NOT switched bandwidth like most modern wired networks, but
shared (like running a hub instead of a full switch)
     Personally not sure about what effect using an AP is having, but this
*could* be reasonable!

    maybe the rest of the list can help you more....

    well done on getting your WLan up & running!

    Rowan

    Cameron Donaghey wrote:

      Hello Everyone,
        I have eventually got my wireless up and running, only on a private
level at the moment, and
      yet I am not entirely sure it is running correctly. I have two
machines and in each one I have
      a Compaq WL100 card set to infrastructure mode. I also have a linksys
Wap11 access point
      which is running as an access point only.
      I have done some testing and I seem to have a max. transfer rate
between the two machines
      of about 310kb/s and the machines are only a meter or so apart. I
would have assumed that
      being a 11mb/s network that I would be able to achieve more so around
500-1000kb/s rather
      than the 300kb/s max. I am currently achieving. Both card say they
have "excellent connections"
      and at 11mb/s.
      My question to you all, is the transfer speed of about 300kb/s typical
for 802.11b or should I be
      able to achieve higher rates of transfer? If I should be able to
achieve more would anyone have
      any suggestions towards resolving the problem?
        Thanks very much,
           Cameron Donaghey



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