MIMO is best solution for urban environment as it takes advantage of multi-path. MIMO technology transmitting the WiFi signals on multiple antennas ( in RTK8822 it is 2 Antennas ) to send parallel signals, while In an urban environment, these signals will bounce off buildings, walls and every object in the way causing the signals to travel in different directions on their way to their destination. that is actually caused "Multi-path" since the same information arrive at the receiver in different signals at various times.