[MLB-WIRELESS] Transfer Rates

[Tony Langdon]

One of the biggest issues I find in a discussion like this is the "mixed
units confusion"  :) 
 
And they get more confusing.  In terms of RAM capacity, HDD capacity or
program data usage, "kilo" is taken to mean 2^10, or 1024, "mega" is 2^20,
etc.  However, in communications, "kilo" has the more conventional value of
1000.  So in terms of throughput, kbps = 1000 bits per second, Mbps =
1000000 bits per second, and for the record... the much maligned "mbps" =
0.001 bits per second (or 1 bit every 1000 seconds), since lower case "m" =
"milli" .

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. 
 

That's probably helpful,and aided by the fact that common tools (including
web browsers) express throughput in bytes/sec.

 
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! 

3 Mbps on Ethernet?  I've had much higher - certainly in excess of 700
kByte/sec, which translates to 5.6Mbps.  I get 4Mbps (500kbyte/sec)
downloading from cable and across my wired Ethernet.
 
Wireless throughput under ideal conditions (quiet channel, 2 stations) has
consistently been measured at around 600 kByte/sec by many parties,
including myself.

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