Telemetry Applications - The Choice between SMS and GPRS

PR Log (Press Release) – Mar 01, 2010 – http://www.icantrack.com/

In the past telemetry applications often used SMS as the communications backbone. This was primarily due to the lack of choice available. As data networks have become more robust and economical, there are more options to choose from. There are a number of determining factors before making your choice.

The key issues when considering which protocol to select involve an understanding of the following criteria:

1. Amount of data per packet

2. Net amount of data per month

3. Cost ( ie what is your monthly budget? )

4. Signal quality

5. Criticality ( how mission critical is your data? )

6. Protocol

With SMS the amount of data is limited to 160 characters. This can be a major bottleneck in many applications. With TCP/IP over GPRS there is no such limit as it is controlled by how you code your server. With UDP there is a packet limit of 256 bytes. SMS is usually more cost effective when there are limited messages sent on a monthly basis. As the net amount of data increases, cost can easily escalate. GPRS is therefore more suitable for applications requiring higher data transmission.

A typical telemetry application in the UK can use a M2M ( Data Only ) SIM costing GBP£2.50/month for 1MB of data transfer. That equates to GBP £0.005/KB (including overheads). With the average cost of an SMS message being GBP £0.05, the equivalent

data cost would be GBP £0.31/KB. So if your application typically sends a maximum of 40 SMS messages per month, it would be more cost effective to select SMS (GSM).

Signal quality is another important issue to deal with. Although SMS can work with a relatively poor signal quality, GPRS requires better signal quality. So although GPRS may be cost effective, if the device is in a remote area, SMS should be given consideration. If you have a GPRS modem you could always use SMS as a backup. Although a GSM modem without GPRS cannot give you GPRS.

Choice of modem is also critical. GPRS modems are generally more expensive than GSM

modems.

If the nature of your data is mission critical and you require guaranteed delivery GSM (SMS ) and GPRS are both suitable, however if your data needs to cross country borders GSM (SMS) is not normally guaranteed. With TCP/IP or UDP over GPRS, application level protocols can be built in to ensure guaranteed delivery.

Even when you select GPRS, your protocol choice of TCP/IP or UDP is critical. UDP has lower overheads but is less reliable. TCP/IP is more reliable but costs are typically higher.

For example— when developing a GPS tracking application, it would make sense to choose UDP/GPRS as the cost of transmitting SMS every few seconds would be astronomical. TCP/IP would also be expensive as overheads are almost 5 times more than

UDP.

Hardware selection is equally critical and poor selection can restrict future functionality and can become very expensive.

identySOL offers icanTRACK as a full 'end to end' solution including an unbiast consultancy service to ensure you choose the right protocol and hardware for your application.

Contact us for more information.

info@icantrack.com

+44 1273 704 529

http://www.icantrack.com/

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