Terminal device, and buffer partitioning method
Disclosed is a terminal apparatus in which: a decoding section ( 210 ) that stores, in a retransmission buffer, downlink data transmitted by each of the plurality of component carriers and decodes the downlink data; and a radio transmitting section ( 222 ) that transmits, using a first component carrier of the plurality of component carriers, a response signal for first downlink data received using the first component carrier and a response signal for second downlink data received using a second component carrier of the plurality of component carriers. In addition, a second buffer is divided into regions respectively corresponding to retransmission processes based on a specific value determined by a combination of a first configuration pattern that is set in the first component carrier and a second configuration pattern that is set in the second component carrier.
1. A terminal apparatus which, in operation, communicates with a base station apparatus using a plurality of component carriers including at least a first component carrier and a second component carrier, the terminal apparatus comprising:
a decoder which, in operation, stores, in a retransmission buffer, first and second downlink data respectively received in the first and second component carriers, wherein a first configuration pattern of uplink and downlink subframes is set for the first component carrier and a second configuration pattern of uplink and downlink subframes is set for the second component carrier; determines a reference configuration pattern of uplink and downlink subframes based on the first and second configuration patterns; stores the second downlink data in the retransmission buffer in reference to a maximum number of downlink HARQ (hybrid automatic repeat request) retransmission processes executable in the determined reference configuration pattern; and decodes the first and second downlink data;
a signal generator which, in operation, generates a first response signal using a result of error detection of the first downlink data and a second response signal using a result of error detection of the second downlink data; and
a transmitter which, in operation, transmits the first and second response signals in the first component carrier.
2. The terminal apparatus according to claim 1 , wherein the transmitter transmits the second response signal in the first component carrier at a timing of an uplink subframe of the reference configuration pattern.
3. The terminal apparatus according to claim 1 , wherein, when the first configuration pattern and the second configuration pattern are different, the transmitter transmits the second response signal in the first component carrier at a timing of an uplink subframe of the reference configuration pattern.
4. The terminal apparatus according to claim 1 , further comprising:
a first table which defines multiple reference configuration patterns respectively corresponding to multiple combinations of the first and second configuration patterns, wherein each of the first and second configuration patterns is selected from a set of configuration patterns, and
a second table which defines multiple maximum numbers of downlink HARQ retransmission processes respectively corresponding to the multiple reference configuration patterns, wherein,
the decoder refers to the first and second tables to determine the reference configuration pattern and the maximum number of downlink HARQ retransmission processes executable in the determined reference configuration pattern.
5. The terminal apparatus according to claim 1 , wherein the first component carrier is a primary cell and the second component carrier is a secondary cell.
6. The terminal apparatus according to claim 1 , wherein the decoder stores, in the retransmission buffer, an LLR (Log Likelihood Ratio) for the first or second downlink data when error is detected, and combines the stored LLR with an LLR of downlink data to be retransmitted.
7. A method implemented in a terminal apparatus configured to communicates with a base station apparatus using a plurality of component carriers including at least a first component carrier and a second component carrier, the method comprising steps of:
storing, in a retransmission buffer, first and second downlink data respectively received in the first and second component carriers, wherein a first configuration pattern of uplink and downlink subframes is set for the first component carrier and a second configuration pattern of uplink and downlink subframes is set for the second component carrier,
determining a reference configuration pattern of uplink and downlink subframes based on the first and second configuration patterns and storing the second downlink data in the retransmission buffer in reference to a maximum number of downlink HARQ (hybrid automatic repeat request) retransmission processes executable in the determined reference configuration pattern,
decoding the first and second downlink data,
generating a first response signal using a result of error detection of the first downlink data and a second response signal using a result of error detection of the second downlink data, and
transmitting the first and second response signals in the first component carrier.
8. The method according to claim 7 , wherein the transmitting step includes transmitting the second response signal in the first component carrier at a timing of an uplink subframe of the reference configuration pattern.
9. The method according to claim 7 , wherein, when the first configuration pattern and the second configuration pattern are different, the transmitting step includes transmitting the second response signal in the first component carrier at a timing of an uplink subframe of the reference configuration pattern.
10. The method according to claim 7 , wherein the determining step includes referring to:
a) a first table which defines multiple reference configuration patterns respectively corresponding to multiple combinations of the first and second configuration patterns, wherein each of the first and second configuration patterns is selected from a set of configuration patterns, and
b) a second table which defines multiple maximum numbers of downlink HARQ retransmission processes respectively corresponding to the multiple reference configuration patterns,
to determine the reference configuration pattern and the maximum number of downlink HARQ retransmission processes executable in the determined reference configuration pattern.
11. The method according to claim 7 , wherein the first component carrier is a primary cell and the second component carrier is a secondary cell.
12. The method according to claim 7 , wherein the storing step includes storing, in the retransmission buffer, an LLR (Log Likelihood Ratio) for the first or second downlink data when error is detected, and combining the stored LLR with an LLR of downlink data to be retransmitted.