Performance

The fundamental data speeds for most mobile data connections is much slower than that achieved with LANs, wireless LANs or even Dial-up connections using a 56k modem.

For Email and messaging use, these slow speed should not be a problem, but for Internet/Intranet access the user experience will be poor unless the system is configured properly and the (Intranet) site designed efficiently.

The three choices for mobile data are Circuit Switched Data (called CSD or GSM Data), High Speed Circuit Switch Data (called HSCSD or High Speed Data) or GPRS (General Packet Radio Service).

To summarize real world data rates for these services:

* In the UK High Speed Circuit Switched Data (HSCSD) is only available from Orange

** These are the maximum rates achievable - GPRS users share bandwidth with other GPRS and Voice users which will often restrict the data rate. New terminals using more timeslots will increase these maximums.

One of the key differences between using GPRS and the other forms of mobile data - GSM CSD or HSCSD is that with GPRS you share the radio bandwidth with other users. Congestion will soon reduce the speed of you connection during busy times during the day and in busy locations. The GSM CSD and HSCSD provide a fixed speed connection though you need to dial up each time it is used and then disconnect at the end of the data call.

Another point in favour of GPRS is that many networks have introduced compression systems to speed up delivery of Internet content to browsers. Transparent to the user, sites appear quicker with the apparent speed of the connection being much faster than the actual speed - some manufacturers claim a five times improvement in speed.

Email

As e-mail is not real time, speed only becomes an issue when sending and receiving large attachments. Sending is particularly difficult as many terminals only have a single channel uplink running at 9-14kbps.

Some GPRS providers are offering email compression software that provides loss-less compresion on the GPRS network for incoming emails. Outgoing emails are under your control so it is easy to compress with one of the common utilities to produce a ZIP or CAB file.

If you fall back to one of the dial up data services when GPRS is busy or unavailable (e.g. when traveling to countries without a roaming network), you must be careful how often you set you Email application to check for emails. Though the call may be short there is often a minimum charge, and checking every five minutes will soon produce a big bill.

Summary

To achieve the best performance you should

1) Choose a network with good compression/optimization for WWW browsing. Not all networks will have this but it can make web browsing approximately 5 times faster - often better than a dial-up connection.

2) Purchase a terminal (phone or PC data card) with a GPRS radio that utilise as many timeslots as possible - some devices were 1 timeslot up (from the phone to the network) and two slots down, more recent devices are 1 up and four down, making web browsing far more usable.

3) Watch out for congestion on the radio network. As there are a fixed number of radio timeslots shared between all voice + data users, during busy periods the GPRS performance will drop dramatically. The performance of the GPRS connection may be monitored with a useful free utility call DUNMON which provides a graphical display of up and down data speeds.

4) Configure your email application with care to avoid unecessary bills if using a dial-up mobile service (CSD, HSCSD).