Challenges

Reliability Of Cellular Connectivity
Intercake machines are generally located in the middle of supermarkets – a nice environment for humans, but potentially not such a nice RF environment for cellular devices trying to reach surrounding cell towers. Metal clad buildings such as supermarkets can do a good job of attenuating radio waves at a variety of frequencies including those used for 3G/4G Communications.
Robustel provided guidance on the choice of a roaming SIM that could connect to all available networks in the vicinity, opting for an ‘unsteered’ roaming SIM that is optimised for best possible chance of a connection – not for the network operator’s commercial benefit as is generally the case with “steered” roaming SIMs.

Multi-network SIMs help significantly to increase overall estate uptime, especially when used in conjunction with Robustel’s “Smart Reboot” capability. “Smart Reboot” is a unique feature in all Robustel routers whereby a text message can be used to push a router from a non-functioning network to one that is fit for purpose.

The outcome of this good practice was very high estate uptime with only a couple of problem stores that could not initially connect due to lack of coverage from mobile network operators.

Qualifying Data Usage
Intercake traditionally used ‘Logmein’ as an occasional remote access solution and it had worked well. However, the move to a 3G/4G solution meant that Intercake needed to be assured that excessive airtime bills would not be accrued as a consequence of using a bandwidth-hungry solution like Logmein.

With only anecdotal information about data usage from airtime bills during the test phase, it was considered risky to roll out a fleet of devices on 4G without more stringent qualification of per session data costs.
To solve this problem, analysis of a typical “logmein” session was completed using the “Sniffer” function contained within all Robustel 4G routers – in essence, all data over the 4G link was captured for subsequent analysis in the brilliant free network analyser package known as “Wireshark”. The conclusion was that an idle Logmein session would accumulate approximately 20KB per second of data and active session approximately 40KB per second.

These fundamental measurements were invaluable in assuring the team at Intercake that the anticipated mode of operation would not pose an unacceptable commercial risk from a 4G data billing perspective. The outcome of using this technique for getting a solid approximation of actual data usage was to save an additional proof of concept phase on a subset of sites to gather real-world measurements. Time to full deployment was quicker & risk was lower as a consequence.

Capital Expenditure for Connectivity
Due to the number of stores requiring internet connectivity, several hundred routers needed to be purchased. At this scale, the absolute cost of each router becomes a key consideration for the feasibility of such a roll-out.
Price/Performance ratio is critical in such an application as buying “cheap” can result in a disaster due to poorly written firmware or non-industrial build quality.

Conversely, the cost of an “over-engineered” solution can kill the business case upfront and 3G/4G connectivity – a key enabler of the Internet of Things – can be out of the reach of some projects.

The Robustel R2000 was able to hit an acceptable price-point to fit the business case as well as providing highly stable long-term communications.