David Yach From RIM: Slams 3G


Chris Justus the CEO of FastBug Track had an opportunity to visit RIM and hear from David Yach on his views about 3G, a wireless technology that can support up to 2Mbps. Here’s his entry on his blog:

So we went to a presentation last week given by David Yach @ RIM – makers of the Blackberry. We weren’t sure what to expect – David gave an excellent talk about wireless technologies in general. He drove home that the following 3 points have to be taken into consideration when working with wireless devices – three limiting factors:

Spectrum – there is only so much, and it costs money to use.

Thermodynamics – processing takes power, and generates heat.

Battery Life – improving much more slowly than Moores law.

These 3 factors drive a spike through the heart of most 3G devices. Battery life constrains a device to being capable of transmiting a fixed # of packets and/or receiving a fixed # of packets (transmitting taking 10x the power as receiving) – and we’re not talking huge numbers here – we’re talking about a device being limited to receiving 5000 packets of data.

Spectrum is a scare resource as well. When bandwidth is being discussed, it is the peak bandwidth, if your device is the only device using all available spectrum – in a crowded area, you are sharing spectrum with multiple devices, and network performance would be reduced. More base stations could be created to spread the load, but the cost is N-squared. (1 device covering a 10 kilometer by 10 kilometer area , to be replaced with devices covering 1k x 1k, requires ~ 100 devices).

Thermodynamics referred to the fact that an electronic device doing things gave off heat, and you don’t want to be burning people using your device.

RIM is big on their push paradigm – rather than having their devices continually asking “Got anything for me?”, and getting a reply “Nope” – they just listen every so often, and eventually get a message “Hey I’ve got something for you…” – a device that doesn’t support push, that queries every 5 minutes, will send 12 packets an hour x 24 hrs = 250 packets in a day (or about 5% of the total battery life), and be getting nothing back for the most part.

He discussed various problems with communication – that request/response can add a fair bit of overhead to a wireless device – that if I was watching a stock price from a webpage, that webpage contains a large amount of fluff that might be getting re-transmitted over and over, when really I just want a couple of bytes of data representing the current price.

There were 2 key points that make wireless application development difficult:

1) Devices aren’t always reachable – (like unplugging the ethernet connection from your PC at random every couple of minutes. How do your network apps behave?) I can be in an elevator, a basement, out of range, out of country, etc.

2) The cost of bandwidth for an enterprise can be a huge factor. Suppose my empty “anything for me?” queries cost 2.5 cents a day, multiply that by my 10,000 employees times 365 business days, means that I’m spending $250 x 300 = $75000 / year on empty “anything for me” messages being sent — Then consider a real application to retrieve pricing in real time, and you could be using serious amounts of bandwidth, and the pricing app ends up with bandwidth costs in the millions.

You can view more about Chris Justus on his blog …