Dynamically change WiFi power on Omega2 LTE

[quiron]

Hi.

I want to dynamically change the wifi antenna power to save battery. I try to set txpower to a lower value.

I try to set it in /etc/config/wireless

config wifi-iface 'ap'
	option device 'radio0'
	option mode 'ap'
	option network 'wlan'
	option ifname 'ra0'
	option encryption 'psk2'
	option key 'xxxxxxxx'
	option disabled '0'
	option txpower '20'
	option ssid 'Omega-xxxx'

But when i try to get the power info

# winfo  ra0 info
ra0       ESSID: "Omega-xxxx"
          Access Point: aa:bb:cc:dd:ee:ff
          Mode: Client  Channel: 1 (unknown)
          Tx-Power: unknown  Link Quality: unknown/100
          Signal: unknown  Noise: unknown
          Bit Rate: 150.0 MBit/s
          Encryption: unknown
          Type: wext  HW Mode(s): unknown
          Hardware: unknown [Generic WEXT]
          TX power offset: unknown
          Frequency offset: unknown
          Supports VAPs: no  PHY name: ra0

There are not information in Tx-power field.
From my laptop the wifi omega strength signal has no change.

I have an Omega2 LTE.

How dynamically change the antenna power?