Friends Don’t Let Friends Use 2.4GHz: 3 Factors to Address before Upgrading
Having a proper wireless survey implemented before deploying any wireless solution is critical in avoiding wireless issues in the future. A wireless engineer can scan the environment and recommend AP placements and channel/power settings to get around adjacent businesses that might have their wireless network broadcasting into your environment. It is also best to scan the room or space being covered with the same model of access point that will be used upon installation to show proper coverage at voice, data, or location signal thresholds. Below is a list of key items that a Wireless Engineer will typically look for when performing a wireless survey and why each of them should be addressed prior to implementation.
Co-Channel interference: You can probably imagine talking in a crowded setting. As you listen to the person talking to you, there might be another person talking to someone else. As both parties continue their conversations, it is hard to tell the difference as to who is talking to you and who is talking to someone else. So to get around that, you either talk louder or wait for the other party to pause their conversation so that you can continue yours. Access points behave the same way. They pause and wait for other access points to stop transmitting/receiving from or to a client, then begin their transmission. Now let’s multiply that by 20 or 30. You can start to picture why some areas of your wireless network might be having problems. Performing a passive wireless survey at your desired location can mitigate this before it disrupts your business.
Nearby Radar in Use: DFS/Radar studies can be performed to understand what channels in the UNII-2 Extended band may be unaffected by nearby radar. Those channels unaffected by DFS Radar events may then be added to the pool of usable channels and thus realize the capacity of that unused spectrum. In short, if it’s not being used by your neighbors, then there is no co-channel interference. Thus, the more channels that are available, the better your wireless network will perform. The FCC also ensures that wireless networks will not affect nearby FAA radar by regulation. The rule states that if an access point hears Radar it must shut down for 60 seconds, then it can continue transmitting if it does not detect the radar again.
Load Balancing: Load balancing issues can result from a number of things. These things can include items like radio signal strength and the distance it will therefore travel. If a client device thinks it has a good signal to an AP, it’s going to connect to it whether or not the AP is overloaded (the client just sees a good signal strength.) Another contributor could be client density in a specific area. If more clients are actively using the airspace in one section of the environment more than another, this could cause load balancing issues. When a client enters the room, they connect theoretically to the AP that it hears first. If the person’s device can still hear that AP from wherever they are sitting, then the device would have no reason to disassociate from it. As mentioned above, the client has no idea the AP is overloaded, it only knows that it has a decent signal strength to the AP itself. Depending on the client (Mac, Android, PC, etc.), their wireless NICs and the age of their devices, they can each behave a little differently when evaluating the wireless environment and will therefore make decisions on how to connect based on that information. Power levels of access points would need to be adjusted to avoid these behaviors.
While it may seem like an extra step in the process, having a survey before deploying a wireless network can save you and your company time and money. Let’s not forget to mention the emails and headaches involved. Save yourself ahead of time, “measure twice and cut once.”
Tom Leon, an ABS Network Engineer, focuses on staying up to date and implementing the latest enterprise networking technologies for ABS’ largest clients.