Methods and stations for power saving in radio communication

1. A method performed by a transmitting station for enabling power saving in one or more receiving stations when the transmitting station transmits a radio signal to a targeted station, the method comprising:

determining a power limitation status of the targeted station;

setting a set of one or more power limitation bits that indicate the determined power limitation status of the targeted station; and

transmitting the radio signal with a preamble including the set of power limitation bits, thereby enabling any receiving station that receives said preamble to determine whether to receive and decode the complete radio signal or not based on the set of power limitation bits, wherein

the set of power limitation bits is set to a first value when the determined power limitation status of the targeted station is power limited,

the set of power limitation bits is set to a second value when the determined power limitation status of the targeted station is non-power limited, and

the set of power limitation bits is set to the first value when the determined power limitation status of the targeted station is unknown.

2. The method of claim 1 , further comprising the transmitting station receiving power limitation information transmitted by the targeted station.

3. The method of claim 2 , wherein determining the power limitation status of the targeted station comprises determining the power limitation status of the targeted station based on the received power limitation information transmitted by the targeted station.

4. A transmitting station arranged to enable power saving in one or more receiving stations when the transmitting station transmits a radio signal to a targeted station, the transmitting station comprising:

a processor; and

a memory, said memory comprising instructions executable by said processor, wherein the transmitting station is configured to:

determine a power limitation status of the targeted station based on power limitation information transmitted by the targeted station,

set a set of one or more power limitation bits, wherein the set of power limitation bits indicate the determined power limitation status of the targeted station, and

transmit the radio signal with a preamble including the set of power limitation bits, thereby enabling any receiving station that receives said preamble to determine whether to receive and decode the complete radio signal or not based on the set of power limitation bits.

5. The transmitting station of claim 4 , wherein the transmitting station is configured to set the set of power limitation bits to a first value when the determined power limitation status of the targeted station is power limited and to a second value when the determined power limitation status of the targeted station is non-power limited.

6. The transmitting station of claim 5 , wherein the transmitting station is configured to set the set of power limitation bits to the first value when the determined power limitation status of the targeted station is unknown.

7. The transmitting station of claim 4 , wherein the transmitting station is configured to determine the power limitation status of the targeted station to be non-power limited when identified as being any of: an Access Point, a base station, and a relay station.

8. The transmitting station of claim 4 , wherein the power limitation information is contained in a beacon transmitted from the targeted station or in signalling from the targeted station during an association or handshake phase.

9. The transmitting station of claim 4 , wherein the transmitting station is configured to determine the power limitation status of the targeted station to be power limited when identified as being any of: a non-Access Point, an Energy Limited station, and a sensor station.

10. A method performed by a receiving station when a transmitting station transmits a radio signal to a targeted station, the method comprising:

transmitting power limitation information indicating a power limitation status of the receiving station;

receiving a preamble of the radio signal, the preamble including a set of one or more power limitation bits, wherein the set of power limitation bits indicate a power limitation status of the targeted station;

determining whether to receive and decode the complete radio signal or not based on the set of power limitation bits.

11. The method of claim 10 , wherein the receiving station receives and decodes the complete radio signal when detecting that the set of power limitation bits has a first value indicating that the power limitation status of the targeted station is power limited.

12. A receiving station comprising:

a processor; and

a memory, said memory comprising instructions executable by said processor, wherein the receiving station is operative to:

transmit power limitation information indicating a power limitation status of the receiving station;

receive a preamble of a radio signal transmitted by a transmitting station to a targeted station, the preamble including a set of one or more power limitation bits, wherein the set of power limitation bits indicate a power limitation status of the targeted station, and

determine whether to receive and decode the complete radio signal or not based on the set of power limitation bits.

13. The receiving station of claim 12 , wherein the receiving station is configured to receive and decode the complete radio signal when detecting that the set of power limitation bits has a first value indicating that the power limitation status of the targeted station is power limited.

14. The receiving station of claim 12 , wherein the receiving station is configured to discard the radio signal when detecting that the set of power limitation bits has a second value indicating that the power limitation status of the targeted station is non-power limited.

15. The receiving station of claim 14 , wherein the receiving station is configured to save power by entering sleep mode after detecting the set of power limitation bits in the preamble of the radio signal.