Method for allocating physical hybrid automatic repeat request indicator channel
A method for allocating a physical hybrid ARQ indicator channel (PHICH) includes allocating a CDM group according to a cyclic prefix type in consideration of a ratio of the numbers of necessary CDM groups according to spreading factors, and allocating a PHICH to the allocated CDM group. The PHICH includes an ACK/NACK signal multiplexed by code division multiplexing (CDM). Therefore, resources for PHICH transmission are efficiently allocated and a transmission structure can be maintained irrespective of a spreading factor.
1. A method for transmitting spread signal by a transmitting end in a wireless communication system, the method comprising:
determining a physical hybrid automatic repeat request indicator channel (PHICH) group index and a spreading code index for transmitting an acknowledgement/negative acknowledgement (ACK/NACK) signal by using an index associated with the ACK/NACK signal;
spreading the ACK/NACK signal using a spreading code which is indicated by the spreading code index among a plurality of spreading codes;
allocating the spread ACK/NACK signal to a PHICH group which is indicated by the PHICH group index among one or more PHICH groups; and
transmitting the one or more PHICH groups to a receiving end through a plurality of subcarriers in orthogonal frequency division (OFDM) symbol,
wherein the PHICH group index is changed as the index associated with the ACK/NACK signal increases by one, and
wherein the spreading code index is changed as the index associated with the ACK/NACK signal increases by the number of PHICH groups.
2. The method of claim 1 , wherein the index associated with the ACK/NACK signal includes an index of uplink physical resource block (PRB).
3. The method of claim 1 , wherein the PHICH group index and the spreading code index are determined by further using a parameter related with demodulation reference signal (nDMRS).
4. The method of claim 1 , wherein the PHICH group index is determined by using modulo Ng operation, where Ng denotes the number of PHICH groups.
5. The method of claim 1 , wherein the spreading code index is determined by using floor function, wherein a parameter of the floor function is a value divided by the number of PHICH groups.
6. The method of claim 1 , wherein spreading code indexes are sequentially mapped to inphase (I) spreading codes and then quadrature (Q) spreading codes.