How Far Will My Wireless Network Go?
The question I get asked the most regarding Wireless Networking is: “How far will it go?” The answer? It depends.
There are many variables that affect how far wireless will actually go. If an “expert” quickly gives you a fixed number — such as 1500 feet — run away.
SIGNAL QUALITY IS EVERYTHING
The first thing to remember about wireless is that transmit power and distance aren’t everything. It’s all about signal quality — a.k.a. Signal-to-Noise Ratio (SNR). I’ve fixed more wireless issues by simply turning down the power, which is counter-intuitive to what you’d think. More power isn’t always the best solution.
ASK THESE QUESTIONS
When conceptualizing the design of a wireless network — whether it’s Wi-Fi, Bluetooth, ZigBee, 900MHz, etc. — you first need to do a little planning, especially in the industrial space.
Prior to putting up Access Points (APs) and Client Radios, ask yourself these three questions:
- Does my application require high speed/data rate, such as streaming multiple HD cameras at high frame rates?
- Is my application low speed/low data rate, such as sensors or I/O only polling once a minute or once an hour?
- How many nodes/hosts will be part of this wireless network, and what is their bandwidth requirement?
The answers to these questions will help you determine what type of wireless solution will best fit your needs. For example, if you’re streaming 10 HD cameras over a Wi-Fi link, you should be looking at an 802.11n or 802.11ac solution, not an 802.a/b/g or 900 MHz solution. You will also need to maintain high levels of receive signal level in order to maintain the high data rate necessary to maintain a good quality video image. In this instance, the APs and Clients need to be much closer together.
Consequently, if you’re polling sensors and/or I/O that don’t require a lot of bandwidth, you could go with an 802.11a/b/g, Bluetooth, ZigBee or 900MHz solution. In the case of 900MHz, the lower connection speeds and frequencies allow your APs and Clients to be much further apart — therefore, less equipment is required. Do some simple math to determine how many nodes will be on the network and how much bandwidth each requires. Adding a little margin for future growth never hurts either.
ALWAYS DO A SITE SURVEY
Once you have gone through the steps above and completed your conceptual design, do a site survey. Even though you ran your numbers on paper, there is no substitute for going to the actual site and performing live testing to see what the RF environment actually is. Use either a spectrum analyzer or a handheld device such as a Fluke, Air Check™ to see if the bands/channels you intend to use aren’t already saturated, and also that there are not other interferers. Set up an AP with the type of antenna you intend to use, and take some measurements. This step will not only assist you in your final design, but will make the implementation and cutover go much smoother.
So before you decide to do your first or next wireless project, remember a little Wireless Planning goes a long way!
Should you need any assistance in choosing the correct products to fit your application, please contact me at The Proud Company at (412) 838-0230 x 113.