Originally posted by: PMK
Thinking about upgrade my WiFi card from g to n standard on the PCI slot. One thing gives me small headache - what's the point to upgrade up to 300 Mbps on a card if standard PCI bus can handle up to 133 Mbps? Even assuming, that average transmission speed between a WiFi card and a router is much lower, say 200 Mbps, there's still much overhead which will wait in a buffer. The only point for such upgrade - what I can see - is that actual average speed for WiFi is around 150 Mbps (or lower) and therefore might roughly match PCI bus speed. Am I right?
The difference is the "b"! 300 Megabits per second and 133 megabytes per second are different speeds. See here
for more information on the general PCI bus.
There are 8 bits in a byte. thus 133 x 8 = 1064 Megabits = 1 gigabit.
Also a PCI bus could be 64bits (8 bytes) wide. Thus can have a burst speed of 1064 Megabytes = 8512 Megabits = 8.5 gigabits!
Also the marketed speed is the one way communcation speed. Each packet sent on a network requires acknowledgement, this reduces the practical speed by half before any error bits are added and or error handling by resending of packets etc. Thus I'd expect a 100Mb (megabyte) file to transfer across a 100mbps (megabit) network to take about 20 seconds.
Point-to-point communication of the "marketed speed" is correct but can be likened to giving the rpm of a tyre when quoting the top speed of a car!
Ian Lowson MIET
Do or do not, there is no try!
08 September 2010 at
05:31 PM by