Engineer solves the mystery of why 'Wi-Fi only works when it's raining'
When he returned to his parents' house for the first time in a while, engineer Predrag Gruevski discovered that he could only use Wi-Fi when it was raining. He posted a blog post about the process of investigating the cause and resolving the problem.
The Wi-Fi only works when it's raining
Gruevski's father was also an engineer, and through a company he founded, he designed and implemented all kinds of complex network systems, from gigabit Ethernet in office buildings to connecting cities via line-of-sight microwave links. So when his father said something like 'rain makes Wi-Fi work,' Gruevski was surprised.
Rain is actually a factor in deteriorating the quality of communication, so Gruevski decided there must be something else causing the problem and decided to check the network. The Wi-Fi Internet connection was working, but no matter what site I tried to open, the packet loss rate was 98% and I couldn't load anything.
But when it started to rain, the situation changed completely. About five minutes after the rain started, the packet loss rate was 0%, and the Internet became available. Gruevski said he couldn't believe his eyes.
After the rain stopped, about 15 minutes later, the packet loss rate rose to over 90%. The Internet connection was unavailable again. During the few days after Gruevski returned to his parents' home, the sky remained cloudy and the rain came and went, and the pattern of the Internet connection being restored every time it rained and then unavailable every time it rose was constantly repeated.
Although Gruevski didn't want to admit that the Wi-Fi was only available when it was raining, the evidence was so clear that he had no choice but to admit it. Although he could have chosen to plan his Internet use based on the weather forecast, Gruevski decided to continue investigating the cause further, saying, 'Screw magical thinking! I'm an engineer!'
The Wi-Fi at Gruevski's parents' home had a special configuration, with a line-of-sight Wi-Fi bridge (
This long-range Wi-Fi hadn't been touched since it was installed 10 years ago. Gruevski made several trips between his home and his father's company to check the parts and cables that make up the long-range Wi-Fi, but he couldn't find any problems with any of the parts he checked.
As Gruevski walked between his home and work in frustration, he suddenly noticed that the neighborhood had changed since he had been away from his parents' home. Many of the small shops had been replaced with new ones, many of the houses had been repainted, and the trees that had been saplings had grown big and tall.
Shocked, Gruevski ran back to his parents' house and checked the Wi-Fi antennas at his company's office, only to find that a tree in the neighbor's yard was swinging between the antennas.
The long-range Wi-Fi had worked fine for many years since the Wi-Fi antenna was installed 10 years ago, but over the years, the neighbor's tree had grown and grown to a point where it was interfering with the Wi-Fi antenna's communications, increasing the Wi-Fi packet loss rate to 98 percent just before Gruevski returned home.
The trees were just tall enough to block the Wi-Fi antennas, so when it rained the weight of the water caused the tree to sag, and communication was restored. After the rain stopped, the rainwater dripped off the tree, blocking communication again.
Gruevski replaced his old 802.11g devices with new 802.11n devices, and says he used math and physics, not sorcery, to make the signal more resistant to interference, so his parents' Wi-Fi worked even on sunny days.
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in Hardware, , Posted by log1d_ts