How labor-intensive is spectrum management if done right (what do you have to do)? What can be successfully automated?
If spectrum management is well integrated into the system, then it should classify and locate devices without requiring any effort. The system should also have some abilities to automatically mitigate interference where possible.
The labor part comes into play when manual intervention is required. Not all devices can be easily mitigated (ex. jammers). And even when automated mitigation is possible, it’s a good idea to remove the interfering device eventually since it is taking up some of your RF capacity. At this point, the human gets into the loop to remove, disable, move, replace, or shield the interfering device. For example, if someone outside of the IT departments sets up a video camera that is jamming all your Wi-Fi channels you can either have it replaced with a wired camera or select another wireless camera that does not use the same 2.4 GHz frequency as your wireless network.
replied to comment from Neil Diener, Cisco Systems
| July 12, 2010 5:54 PM
| Reply
Neil - your example of the wireless/wired camera begs the age-old question as to whether wireless LANs can ever really approach the reliability of wired Ethernet. What if that camera were installed by someone in the office next door? It's great that spectrum analysis can discover equipment interfering with your network, regardless of whose it is. But what can you do about it if that equipment belongs to someone else? The unlicensed airwaves are an equal-opportunity medium.
In a single tenant building, you can create and enforce a spectrum utilization policy. But as you point out, in a multi-tenant building this can be harder to control.
One thing that helps is that there is a good amount of spectrum in the unlicensed band, and so in most cases it's not likely that a neighbor would cause interference on all channels.
But if you did run into this kind of situation, a few other potential solutions would be: 1) talk to your neighbor and explain the problem, and see if they are willing to change their devices 2) put some RF shielding in place to minimize the impact of their devices, and 3) work through your landlord to resolve the situation -- similar to the way you might handle it if you having a neighbor tenant who bangs on the walls or plays loud music.
At the end of the day, the unlicensed band does have limited regulatons and so limited recourse when you are being interfered with. But in most realistic cases these kinds of issues can be worked out amicably.
This is dependent on the actual application for the spectrum analysis product.
Let us consider the case of a pre-deployment scenario, where the IT staff member has to manually walk around the facility with the product to perform the initial RF spectrum sweep. This may appear to be labor-intensive and does involve spending time, effort and money on the project, but it is absolutely worth the investment. It empowers the staff to make sound RF and WLAN design decisions and to avoid any pitfalls with the operation of the WLAN network in the future. This additional effort can be mitigated by the fact that there are site survey tools that integrate with mobile spectrum analyzers, allowing the collection of RF spectrum information at the same time as the WLAN site survey, in a single walk through the facility. AirMagnet Survey PRO integrates with all industry-leading spectrum solutions like AirMagnet Spectrum XT, AirMagnet Spectrum Analyzer, Fluke Networks AnalyzeAir and Cisco Spectrum Expert, to provide this unique and important phase in the design of the WLAN. This one-time sweep is no different than planning out a wired network in terms of the level of detail and time involved.
Removing the interference source, or shielding the network from it, is one of the best solutions for dealing with interference issues and requires devices to be physically located. Let us consider a case where the interference source maybe hidden from normal view and a mobile spectrum analyzer is needed to pinpoint its location. This will call for the IT staff member to walk around the facility using the device locator, or find a tool built inside the spectrum analyzer product. However, best practices, as recommended by the spectrum vendor and the ease of use of this feature within the spectrum product, go a long way in making device location quick, efficient and effective.
Let us consider the next case, where users have a distributed spectrum solution deployed in their facility. This implementation is very helpful when 24 X 7 monitoring is needed for the network or the IT staff is responsible for monitoring multiple floors or buildings across a campus or branch offices. In this scenario, dedicated spectrum sensors are placed in different locations on the floor to monitor the RF environment on a continuous basis. They alert the user automatically as soon as the interference source is detected. As mentioned in the first section, this alert can be delivered to the user via email, page messages or even sent to a centralized SNMP or syslog server. Users could also choose to capture and save all of the RF information as forensic evidence for any remote location.
The important thing to remember is that whatever maybe the effort or automation involved, spectrum solutions must be on the mandatory list of monitoring solutions for every IT staff member responsible for the successful operation of the WLAN. A well-planned solution that includes RF spectrum sweeps can continue to be successfully managed and maintained with the automated spectrum management solution.