re: 'always on'
<< Chaz - What is (GPXS) "always on" worth actually? "...But perhaps the greatest misconception is that GPRS, and later 3G, will offer an "always-on connection". >>
You neglected to point out that Telstra's comments on GPRS "always on" apply equally (it least in the context of what you quoted to CDMA packet data.
Additional comments:
From Peter Rysavy:
>> If the user has a GPRS-capable mobile telephone, then he or she can receive a voice call while in a data session. GPRS defines three classes of user devices. Class A can handle voice and data simultaneously, class B can handle voice and data sequentially, and class C can handle data only. With a class B device, the most likely of initial devices, the network can notify a user of an incoming call, enabling the user to suspend the data session and accept the voice call. <<
These comments came out if the IBC GPRS Congress held in Rome during mid-May 2001:
>> 'Always-on' Issues and IP Addressing
During the conference, the issue of GPRS being an 'always-on' system was questioned on a number of occasions. It appears that, at least in the short term, there will be many occasions when a GPRS terminal is not 'always-on'.
Issues arise from a number of factors.
* IP addressing - there are just not enough IP addresses available for an individual designation to be issued to each GPRS handset; this means that connected terminals must use a dynamic IP address assigned by the network for the duration of a session. It follows that where the session terminates, the handset will, effectively, no longer be connected. This will appear to the user as a delay in response as the handset waits for the network to re-establish addressing. An alternative approach for operators is to employ Network Address Translation (NAT) where the network operates a system of 'private' IP addressing and where address translation takes place when access to the global internet is required
* Network congestion - an 'idle' GPRS terminal will still consume network resource even though there is no exchange of data. This may become a significant overhead for operators if numbers of users grow and they may need to take steps to limit this for low revenue users
* Handset issues - it appears that some of the early handsets (even so-called Class B handsets) do not have the in-built functionality to maintain network sessions when non-data features are used. <<
- Eric - |
