Bob's Adventures in Wireless and Video Headline Animator

Saturday, January 29, 2011

You get what you pay for

This week I was asked by a customer what the difference was between a commercial grade wireless router and a consumer grade router. The answer is performance.

I found a site called Small Net Builder that runs benchmarks on a variety of equipment. One of the tests they run is for wireless routers. They use Ixia Chariot to test end to end performance between a wireless client and a end node connected over Ethernet. This is the same testing method that we have used for years.

The following chart shows what the top 4 802.11N consumer routers on the market can do. These are routers that cost upwards of $200 and are for indoor use.

As you can see even under ideal conditions, at short range, indoors, with a 40MHz MIMO channel the throughput can barely exceed 100Mbps. This is UDP performance, not even TCP and the distances are only 65 feet maximum. Generally the best performance was at 6 feet apart.

Remember that these are routers that are advertised at 300Mbps. This is theoretical throughput under ideal conditions with a processor architecture capable of supporting such data rates.

So what is the deal? Wireless routers have processors, buses, memory, radio modules, cavity filters, and antennas. When building a router you can choose components which are price oriented or performance oriented. Consumer routers are designed to be affordable. The processors have limited packet forwarding capacity. The bus speed may be too slow to keep up with network traffic. The clock speed of the processor may be too slow. The memory may be insufficient to buffer enough traffic to make up for retransmissions, etc.

A commercial router, like those from HauteSpot, is designed for performance. When we design our routers we look at the entire system and make sure that all components are balanced. Our processors are fast with clock speeds of 680MHz, our memory is large (128MB or more), our bus speed is fast, our radios are high gain and designed for range and performance. The result is that running the same test, at 500 feet we are able to achieve 120Mbps TCP and 95Mbps TCP. You simply cannot achieve this type of performance with parts in the consumer price range.

Further, if you wanted to to run protocols like our TDMA like protocol (TLP) or in full duplex mode, consumer class routers would not have the capacity to support the demands of these demanding applications.

So, pretty much you get what you pay for. If you need performance to support wireless video applications like megapixel surveillance, then you have to have the right architecture. That is why commercial wireless routers cost as much as they do. You can pay less, but you will not get the performance you need.

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