How to Create a STA in OpenWRT and TL-MR3040

/etc/config/network
config interface 'loopback'
        option ifname 'lo'
        option proto 'static'
        option ipaddr '127.0.0.1'
        option netmask '255.0.0.0'

config interface 'lan'
        option ifname 'eth0'
        option force_link '1'
        option type 'bridge'
        option proto 'static'
        option ipaddr '192.168.1.2'
        option netmask '255.255.255.0'
        option ip6assign '60'

config interface 'wwan'
        option proto 'dhcp'

/etc/config/wireless

config wifi-iface

        option ssid 'radiomaze1'

        option encryption 'none'

        option device 'radio0'

        option mode 'sta'

        option network 'wwan'

        option bssid 'XX:XX:XX:XX:XX:XX'   #your BSSID here