We are having strange problem, where there are no data is being sent to some devices. For example, we can have a tablet sitting next to the Edison, with strong WiFi signal and no interference, and video being streamed without any problems, and then we connect another tablet to it and it will stop data for about 20-30 seconds, and then small amount would get through and then that drop off repeats. So essentially our frame rate drops from 10 fps to 2 per minute.
It could also happen with single device - it would be connected to Edison with strong WiFi but only send data through every 20-30 sec.
Edison, running netcat to transfer tcp data. We run Edison as hotspot using stock hostapd (2.1).
Here are the steps:
- Load stock Edison image (problem appears with both image in edison-image-ww25.5-15.zip and iot-devkit-prof-dev-image-edison-20160606.zip)
- Configure wifi access point:
- Login over serial console and enable wifi access point with commands:
- Boot computer to Ubuntu 14 using live usb stick (install on harddisk not needed)
- Connect to Edison wifi.
- Start two terminals
- In terminal 1: enter command: "ping 192.168.42.1"
- In terminal 2: enter command: "nc -v -l -n -p 2222 > /dev/null" (netcat listens at port 2222 and discards received data)
- You can also start "system monitor" to monitor wifi data
You now have two computers pinging the Edison without problems.
- Start sending data to computer A (assuming computer A has ip 192.168.42.20) with command: "cat /dev/zero|nc 192.168.42.20 2222"
- The problem is that somehow computer A wifi locks up the Edison wifi completely for some time, also for other devices connected.
- If a wifi "hiccup" does occur, it can be resolved by trying to associate any other device to the Edison wifi access point. No matter if the password is correct or not.
- Different hostapd version does not resolve problem (I tried both 2.1 and 2.5)
- When using another OS on computer A the problem might not necessarily occur as well.
- When using another wifi adapter on computer A (same OS), like Atheros AR9271 the problem does not occur ( and data throughput is ~3x higher!)