Method and apparatus for improving HARQ in a non-terrestrial network
The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). Disclosed is a method of operating a base station in a non-terrestrial network telecommunication system, comprising the steps of: the base station detecting a block fading condition in a communication channel; the base station determining an average spectral efficiency value and reporting this to a user equipment in communication with the base station; and the base station allocating a modulation and coding scheme and activating a pre-emptive HARQ operation wherein the pre-emptive HARQ operation comprises the steps of: the base station determining an average fade duration; and sending multiple copies of a given data packet separated by a time at least equal to the average fade duration, with an MCS level matching a signal level associated with a non-fading condition of the communication channel.
1. A method performed by a base station in a wireless communication system, the method comprising:
identifying an average fade duration of a block fade based on a pattern of a hybrid automatic repeat request acknowledgment (HARQ-ACK) received from a user equipment (UE) via a physical uplink control channel (PUCCH); and
in response to identifying the average fade duration of the block fade:
identifying a number of re-transmissions based on the average fade duration, wherein the re-transmissions are spaced at a time interval greater than the average fade duration,
transmitting, to the UE, an average spectral efficiency (SE) level corresponding to a duty cycle of UE channel quality indicator (CQI) reporting via radio resource control (RRC) signaling,
transmitting, to the UE, downlink control information (DCI) allocating a modulation and coding scheme (MCS) level according to a channel state in which a fade does not exist, wherein the DCI indicates that data is repeatedly transmitted, and
repeatedly transmitting, to the UE, data by using at least two symbols that have the time interval,
wherein the average fade duration is indicated to the UE based on a ratio of a SE level associated with the MCS level and the average SE level transmitted to the UE.
2. The method of claim 1 , wherein the block fade is a channel state in which a first period in which fade exists and a second period in which fade does not exist alternate.
3. The method of claim 1 , wherein the number of the re-transmissions is further based on fade depth of the block fade.
4. The method of claim 1 , further comprising:
receiving, from the UE, a HARQ-ACK with regard to the repeatedly transmitted data.
5. A method performed by a user equipment (UE) in a wireless communication system, the method comprising:
transmitting, to a base station, a plurality of hybrid automatic repeat request acknowledgement (HARQ-ACK) messages via a physical uplink control channel (PUCCH);
receiving, from the base station, a signal identifying a block fade based on a pattern of the HARQ-ACK messages;
receiving, from the base station, an average spectral efficiency (SE) level corresponding to a duty cycle of UE channel quality indicator (CQI) reporting via radio resource control (RRC) signaling;
receiving, from the base station, downlink control information (DCI) allocating a modulation and coding scheme (MCS) level according to a channel state in which a fade does not exist;
identifying re-transmissions of data based on the MCS level;
identifying an average fade duration based on a ratio of a SE level associated with the MCS level and the average SE level, wherein a number of the re-transmissions is based on the average fade duration, wherein the re-transmissions are spaced at a time interval greater than the average fade duration; and
repeatedly receiving, from the base station, data by using at least two symbols that have the time interval.
6. A base station in a wireless communication system, the base station comprising:
a transceiver; and
at least one processor coupled with the transceiver and configured to:
identify an average fade duration of a block fade based on a pattern of a hybrid automatic repeat request acknowledgment (HARQ-ACK) received from a user equipment (UE) via a physical uplink control channel (PUCCH), and
in response to identifying the average fade duration of the block fade:
identify a number of re-transmissions based on an average fade duration, wherein the re-transmissions are spaced at a time interval greater than the average fade duration,
transmit, to the UE, an average spectral efficiency (SE) level corresponding to a duty cycle of UE channel quality indicator (CQI) reporting via radio resource control (RRC) signaling,
transmit, to the UE, downlink control information (DCI) allocated allocating a modulation and coding scheme (MCS) level according to a channel state in which a fade does not exist, wherein the DCI indicates that data is repeatedly transmitted, and
repeatedly transmit, to the UE, data by using at least two symbols that have the time interval,
wherein the average fade duration is indicated to the UE based on a ratio of a SE level associated with the MCS level and the average SE level transmitted to the UE.
7. The base station of claim 6 , wherein the block fade is a channel state in which a first period in which fade exists and a second period in which fade does not exist alternate.