October 14, 2016
The continual rise of accessing the Internet via mobile devices and consumers’ desire to be connected at all times has maximized 4G network capacity. Consumer demand for mobile data is exponential and shows no signs of slowing. According to a report by Mobile Experts, LLC, we consumed mobile data at a rate of over 10 Exabytes per month in 2014, and by 2020 this rate is projected to increase to over 70 Exabytes per month (table 1).
The overcrowded RF spectrum and use of unlicensed and licensed signals make interference a major issue that is also trending upward. With the number of possible interference sources increasing, it’s not a question of if, but when it will happen to a network under your responsibility.
For years, field technicians out on an RF interference hunt were armed with a handheld spectrum analyzer, appropriate antennas, maybe some mapping software and other tools. These solutions are excellent for signals causing interference on a regular or constant basis. If the signal is only present occasionally, or if a very fast response time is necessary, a short-term or long-term spectrum monitoring solution has proven to be more effective.
With the rapid expansion of wireless communications, the need for robust networks relatively free of interference is a necessity. Capacity can be degraded by the presence of illegal or unlicensed signals that interfere with legitimate transmissions. These interfering signals can be periodic or present at different frequencies over time, making their discovery and removal a significant challenge. Spectrum monitoring tools can help correct this problem.
Spectrum monitoring can also serve to enforce compliance with government regulations. Public safety, air traffic control, railroads using positive train control, and military must all have access to communications free of impediments and distortion. Compliance with spectrum regulations is often enforced by spectrum monitoring. Selecting the Proper Remote Spectrum Monitoring Tool Remote monitoring can be as simple as setting up a handheld spectrum analyzer to record traces and checking back in a week, or as complex as using dedicated rack mount spectrum monitors (figure 1) in combination with networked software to continually characterize the spectrum and locate interference sources. Selecting the best remote monitoring tool is dependent on how it will be used. Here are four common scenarios:
- Real-time Remote: Traveling to and from an area can exceed the time spent doing spectrum monitoring and interference location. Often the source of interference is gone by the time the engineer arrives. Real-time remote monitoring allows for instantaneous “on site” analysis when the need arises, and for engineers to make measurements in several places at once.
- Spectrum Recording Network: Interference affecting public safety, critical communications, and cellular telephony can occur at all hours. Unusual propagation caused by fog and atmospheric temperature inversions often occurs at night, when engineers are off the clock. Deliberate interferers (aka “jammers”) will often operate at night or on weekends, when they can maximize effect without being detected. Spectrum recording networks allow engineers to “go back in time” and make measurements on events that occur during off-hours.
- Alert on Event: In cases of critical interference, or when interference from a suspected source is transient, it helps to provide engineers with an immediate alert when pre-programmed conditions are met. This is typically done by activating a limit line and generating an email or text message when the signal level exceeds or drops below the limit.
- Location by Triangulation: By coordinating the on-board clock of at least three spectrum monitoring stations and knowing their GPS coordinates, the location of an interference source may be automatically estimated by mathematical methods. Location estimation provides an optimized starting point for engineers when beginning their search for an interference source.
To learn more about remote spectrum monitoring tools and their importance in tracking down interfering signals, visit a new technology page.