Method of transmitting channel quality indicator
A method of transmitting channel quality indicator (CQI) includes obtaining CQI of each, of the plurality of sub-bands, selecting a first sub-band having the best CQI of the plurality of sub-bands, transmitting the best CQI of the first sub-band at a first transmission cycle and transmitting a difference value between the best CQI of the first sub-band and a CQI of the first sub-band at a second transmission cycle. Signalling overhead due to CQI transmission can be reduced.
1. A method of transmitting a channel quality indicator (CQI) in a wireless communication system, the method comprising:
transmitting a request for approving a CQI transmission scheme to a base station;
receiving an approving signal for the request;
generating CQIs according to the CQI transmission scheme; and
transmitting the generated CQI to the base station;
wherein the CQI transmission scheme comprises:
obtaining a CQI of each of N sub-bands at a first transmission cycle;
selecting a first sub-band having the best CQI and M−1 sub-bands having CQIs lower than the best CQI in the N sub-bands at the first transmission cycle;
transmitting the best CQI of the first sub-band and difference values between the best CQI and the CQI of each of the M−1 sub-bands at the first transmission cycle; and
transmitting only a difference value between the best CQI of the first sub-band and a CQI of the first sub-band at a second transmission cycle;
wherein the CQI of each of the M−1 sub-bands at the second transmission cycle are determined by using the difference value between the best CQI of the first sub-band and the CQI of the first sub-band at the second transmission cycle.
2. The method of claim 1 , wherein the CQI transmission second scheme further comprising comprises:
transmitting indices of the first sub-band and the M−1 sub-bands.
3. The method of claim 1 , wherein the method further comprising:
receiving information for the first transmission cycle and the second transmission cycle of CQI and a threshold time from the base station.
4. The method of claim 1 , wherein the approving signal for the request includes information indicating time duration which is applied to the CQI transmission scheme.
5. An apparatus of transmitting a channel quality indicator (CQI) in a wireless communication system, the apparatus comprising: a receiver; a transmitter; and a controller, coupled to the receiver and the transmitter, and configured to:
transmit a request for approving a CQI transmission scheme to a base station;
transmit an approving signal for the request;
generate CQIs according to the CQI transmission scheme; and
transmit the generated CQI to the base station;
wherein the CQI transmission scheme comprises:
obtaining a CQI of each of N sub-bands at a first transmission cycle;
selecting a first sub-band having the best CQI and M−1 sub-bands having CQIs lower than the best CQI in the N sub-bands at the first transmission cycle;
transmitting the best CQI of the first sub-band and difference values between the best CQI and the CQI of each of the M−1 sub-bands at the first transmission cycle; and
transmitting only a difference value between the best CQI of the first sub-band and a CQI of the first sub-band at a second transmission cycle,
wherein the CQI of each of the M−1 sub-bands at the second transmission cycle are determined by using the difference value between the best CQI of the first sub-band and the CQI of the first sub-band at the second transmission cycle.