Methods and apparatus for downlink Physical Hybrid Automatic Repeat-reQuest (HARQ) Indicator Channel (PHICH) mapping and channelization in a communication system. First, a base station assigns uplink (UL) physical resource block (PRB) indices to a set of units of user equipment in a cell. Then, for each user equipment, the base station calculates an index triple (KPHICH,0,KPHICH,1,KPHICH,2) for three repetitions of a PHICH signal to be transmitted to the user equipment, with KPHICH, i being a PHICH index indicating a PHICH resource for transmitting the i-th repetition of the PHICH signal to the user equipment, and i=1, 2, 3. When a data packet is received from a unit of user equipment transmitted via at least one physical resource block (PRB) indicated by the at least one PRB index that is assigned to the user equipment, the base station transmits PHICH signals to the user equipment by using the PHICH resources indicated by the PHICH indices assigned to the user equipment.