Method and apparatus for power control in a wireless communication system
View Patent ↗A method and apparatus for power control of the re-transmission data packet in a wireless communication system is disclosed. A first wireless communication device is provided that receives ( 210 ) a data packet from a second wireless communication device and determines ( 220 ) if the data packet is correctly decoded. If the data packet is not correctly decoded, the first wireless communication device calculates ( 230 ) a first re-transmission power required for correctly decoding the data packet based on a signal to noise ratio (Eb/No) versus frame error rate (FER) relationship. And further calculates a power difference ( 240 ) between the calculated re-transmission power and the power of the received data packet and transmits the power difference ( 250 ) to the second wireless communication device. The second wireless communication device calculates ( 340 ) a second re-transmission power based on the received power difference and re-transmits ( 350 ) the data packet at the calculated re-transmission power.
1. A method for power control by a first wireless communication device, the method comprising:
receiving a data packet from a second wireless communication device;
determining if the data packet is correctly decoded;
if the data packet is not correctly decoded, calculating a first re-transmission power required for correctly decoding the data packet based on a signal to noise ratio (Eb/No) versus frame error rate (FER) relationship;
calculating a power difference between the calculated first re-transmission power and a power of the data packet; and
transmitting the power difference to the second wireless communication device.
2. The method of claim 1 further comprising, if the data packet is correctly decoded, transmitting an ACK.
3. The method of claim 1 , wherein calculating a first re-transmission power comprises calculating a first re-transmission power associated with a target signal quality.
4. The method of claim 1 , wherein the Eb/No versus FER relationship is stored in form of at least a curve, a table, an algorithm, or an equation.
5. The method of claim 1 , wherein the Eb/No versus FER relationship is pre-stored in the first wireless communication device.
6. The method of claim 1 , wherein the Eb/No versus FER relationship is generated using simulations in the first wireless communication device for at least one modulation technique and at least one coding scheme.
7. The method of claim 1 , wherein the Eb/No versus FER relationship is received by the first wireless communication device from a base station.
8. The method of claim 1 , wherein transmitting further comprises:
sending the power difference along with a response NACK.
9. The method of claim 1 further comprising:
receiving, by the second wireless communication device, the power difference;
calculating, by the second wireless communication device, a second re-transmission power required for correctly transmitting the data packet based on the received power difference; and
re-transmitting, by the second wireless communication device, the data packet at the calculated re-transmission power.
10. The method of claim 9 , wherein the first re-transmission power is equal to the second re-transmission power.
11. The method of claim 10 further comprising:
receiving a re-transmission of the data packet from the second wireless communication device at the second re-transmission power.
12. A method for re-transmitting data by a wireless communication device, the method comprising:
transmitting a data packet to another wireless communication device;
determining if an ACK is received for the data packet;
if the ACK is not received for the data packet, receiving a power difference from the another wireless communication device;
calculating a re-transmission power required for correctly transmitting the data packet based on the received power difference; and
re-transmitting the data packet at the calculated re-transmission power.
13. The method of claim 12 , wherein the power difference is received along with a response NACK.
14. The method of claim 12 , wherein calculating further comprises:
adding the power difference to a power of the data packet, wherein the power of the data packet is the power at which the data packet was transmitted.
15. A wireless communication device comprising:
a receiver for receiving a data packet from another wireless communication device;
a re-transmission power calculator for calculating, when the data packet is not correctly decoded, a re-transmission power required for correctly decoding the data packet based on a signal to noise ratio (Eb/No) versus frame error rate (FER) relationship and for calculating a power difference between the calculated re-transmission power and a power of the data packet; and
a transmitter for transmitting the power difference to the another wireless communication device.
16. The wireless communication device of claim 15 further comprising:
a memory for storing the Eb/No versus FER relationship for at least one modulation scheme and at least one coding scheme.
17. A wireless communication device comprising:
a transmitter for transmitting a data packet to another wireless communication device;
a receiver for receiving a power difference from the another wireless communication device; and
a re-transmission power controller for calculating a re-transmission power required for re-transmitting the data packet based on the received power difference.