Remember, you pay for the bandwidth of the pipe (i.e. 8mb), at no point do they commit to actualy send 8mb down said pipe....
Yea, but the Vodafone Broadband Signal comes through the window! from the nearest Radio Site, so if they tell you its XYZ Mbps then it should be XYZ.
Makes no odds, the radio setups do much the same as wifi, they back the speed off as the signal quality drops (BER rises).
No, sorry disagree, The whole idea of, when it was lanched GPRS (2.5G, 56kbps) was it was a Radio signal version of ISDN, so you ever get it or not. when 3G was lanched (384kbps) it was on a different carrier signal, so again you get it or you revert back to 2.5G (56kbps). Now we have 3.5G (HSDPA) which is a compressed version of 3G but still on a different carrier (Vodafone currently run a Max of 7.2Mbps) but its still Radio ISDN (although they call it Broadband), the point is, that thier advartising 7.2 Mbps but only supplying 3.5 Mbps, if the signal is crap it will revert back to a lower carrier of 3g or worse case gprs (2.5G).
Unlike WiFi which sets its speed on error bit checking which it feels comfortable with.
In all of these scenarios the connection the mobile network provides is packet switched rather than circuit switched so the analogy with ISDN is not quite accurate.
The network is contended and, whilst the network will negotiate a quality of service with you when you establish a session it doesn't allocate any resources to you for the duration of that session, so you are still competing with other users for the bandwidth available to the mobile network. The mobile network is responsible for allocating those resources dynamically and it will do so based on the amount of data queued and the quality of service to which a user is subscribed.
If you encounter bad signal conditions there is no alternative but to back off the bandwidth in order to provide a continued connection and this is achieved not necessarily by dropping back to a different technology but switching to a more robust form of channel coding that adds redundancy and therefore reduces the throughput.
In short, the situation with a mobile "broadband" conenction is just the same as with wired. You are being sold a theoretical throughput and are getting a practical throughput that will be somewhere between zero and the theoretical throughput.
Kevin
Edited to say: Of course, you can have a circuit switched conenction over a mobile network but 99% of internet access through mobile networks is packet switched.
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Topic: broadband speed (Read 4973 times)