Event Technology: Myth Busting #2

Event Technology Myths

In the second part of our myth busting we look at satellite, high density Wi-Fi and broadband speed.

Satellite is the best all round solution for quick event deployment – BUSTED

Over the last few years KA band satellite has become a cheap option for temporary internet access, it can be a great solution in certain cases but there are many cases where it is not suitable. Satellite suffers from a high latency due to the distance to the satellite and this means every piece of data takes around 600ms to cross space. That delay might not seem much but it is crippling to services such as VPN (Virtual Private Networks), VoIP, video calls, online gaming and any application which requires lots of rapid two-way data traffic. It is great however for large file uploads and video streaming, however, it is important to watch data usage as this can rack up significant additional costs.

Satellite is also a poor solution for wide-scale access such as public Wi-Fi, this is because of a technology it uses to try and boost speed, the downside of which limits the number of simultaneous users who can connect to one satellite service. Most KA satellite services also have high contention ratios which can reduce the advertised 18Mbps/6Mbps type speeds down to something considerably lower, a similar trick is used with home broadband services. Uncontended services are available but the cost is much higher and other than for short durations (it’s normally sold in 15 minute slots) it is not competitive with other solutions.

Satellite can absolutely be the right approach, and we deploy lots of satellite solutions, but understanding the user requirements and explaining what the user experience will be like are extremely important to avoid disappointment and frustration.

Better Wi-Fi just means using more Wi-Fi access points – BUSTED

One of the most common problems with Wi-Fi networks is too many Wi-Fi access points and a poor design. A typical response to a user complaining about Wi-Fi is for another Wi-Fi access point to be deployed to ‘improve coverage’, yet frequently this just makes matters worse. Large scale and high density Wi-Fi requires very careful design to avoid what is known as Co-Channel Interference (CCI) where multiple wireless access points are in effect shouting at each other and slowing the whole network down.

Using fewer high capacity managed wireless access points with a detailed radio spectrum design, often with focused antennas, can deliver much high capacity and a better user experience than a thick blanket of access points. Good Wi-Fi design is a technical art requiring some very detailed knowledge – the output though is pretty much invisible to the normal user until it doesn’t work!

20Mbps of broadband speed is always the same – BUSTED

It would be nice if the experience and speed of all broadband services were the same so that when you are told you have 20Mbps that’s what you get. Reality is somewhat different and more complex due to a number of factors:

  • Contention Ratio – Nearly all providers contend their services, which effectively shares the capacity between multiple users, this can be as much as 50:1 whereby your 20Mbps is shared between 50 users! More normally 20:1 is seen, then 5:1 on more business (and expensive) orientated services, up to the perfect 1:1 (no contention).
  • Asynchronous / Synchronous – ADSL and FTTC (known as BT Infinity but also sold under different names) services are asynchronous, this means that the download speed is not the same as the upload speed. The original principle was that people need more download than upload speed but with modern cloud services, video calls and general rich media this has changed considerably and a low upload speed can be more crippling than the download speed. For example, you may have an ‘20Mbps ADSL service’ but typically the upload is only 768kbps and if the upload is at capacity the download becomes throttled due to the way TCP/IP networks work. Services such as true optic fibre (also sometimes called leased lines) are synchronous.
  • Connection Speed / Throughput Speed – This is primarily an issue for ADSL/FTTC but can be seen with other services too. The speed advertised by an ADSL modem when it connects is only the theoretical speed of the link between the modem and the local exchange. The real throughput or speed depends on the entire route from your computer to the location you are connecting to – this is a complex web of routers, fibre and ‘internet peering’. Different parts of that route may suffer congestion and reduce the overall speed of the connection. Choice of Internet Service Provider (ISP) is an important factor as the good ones have better peering and higher capacity links to reduce the risk of congestion and optimise routing.
  • Latency – Every device, cable and piece of fibre on a network through which data has to pass introduces an element of latency or delay- that’s due to physics. The amount of delay depends on distance (hence why satellite is a problem), quality of links (a poor link needs to use more error correction which adds delay), utilisation of links (high utilisation adds delay) and the number of routers, switches, etc. in the path. Good services may only add a few milliseconds of latency, poor ones several hundred milliseconds and that can make a big difference to user experience.

That’s it for issue 2. Next time, does my microwave really break my Wi-Fi? How comes Wi-Fi works through walls but not though trees? And should you worry about network security.

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