Patent ID: 9730188
Date: 2017-08-08
CPC Classifications: H04B,H04J,H04L,H04W

Claim:
1. A terminal apparatus comprising: a layer mapper which, in operation, maps a first codeword to a first layer and a second layer, and maps a second codeword to at least a third layer that is different from the first layer and the second layer; a reference signal generator which, in operation: a transmitter which, in operation, transmits the mapped first codeword with the generated first demodulation reference signal and the generated second demodulation reference signal, and transmits the mapped second codeword with the generated third demodulation reference signal; and a receiver which, in operation, receives ACK/NACK information indicating an error detection result of each of the transmitted first codeword and the transmitted second codeword, wherein, when the received ACK/NACK information denotes a retransmission request of the first codeword that is mapped to the first layer and the second layer, the reference signal generator generates a fourth demodulation reference signal for retransmission by using a fourth orthogonal sequence and generates a fifth demodulation reference signal for retransmission by using a fifth orthogonal sequence, the fourth demodulation reference signal and the fifth demodulation reference signal being respectively associated for the first layer and the second layer, the fourth orthogonal sequence for the first layer being the same as the fifth orthogonal sequence for the second layer, regardless of whether the first orthogonal sequence is the same as the second orthogonal sequence or the first orthogonal sequence is different from the second orthogonal sequence in a previous transmission, and wherein the transmitter retransmits the first codeword that is mapped to the first layer and the second layer with the generated fourth demodulation reference signal and the generated fifth demodulation reference signal.