iwlist wlan0 scan |grep 'Address:\|Channel:\|Quality\|ESSID'
Cell 01 - Address: 40:70:09:3F:A7:50
                    Channel:6
                    Quality=53/70  Signal level=-57 dBm
                    ESSID:"TG1672G52"
Cell 02 - Address: D8:50:E6:D7:EA:1E
                    Channel:8
                    Quality=70/70  Signal level=-20 dBm
                    ESSID:"ASUS"
...

Wifi Channel-frequency