A method for mapping a physical
hybrid automatic repeat request indicator channel, PHICH, in groups of a plurality of PHICHs, to
orthogonal frequency division multiplexing, OFDM, symbols, each OFDM symbol comprising of a plurality of
resource element groups, each
resource element group being comprised of four resource elements, the method comprising: • determining indexes of
resource element groups in which the PHICH is transmitted, the method being characterised in that said indexes are determined according to a
cell identifier, ID, multiplied by the ratio n l i ' ' / n 0 ' or n l i ' ' / n 1 ' of the number n l i ' ' of available resource element groups in the OFDM symbol, having index l i ' , in which the i th repetition of the PHICH of a PHICH group is transmitted, i being an integer of 0 to 2, and the number n 0 ' or n 1 ' of available resource element groups in the first OFDM symbol, having index 0, of a sub-frame or in the second OFDM symbol, having index 1, of a
subframe, the PHICH being transmitted through one, two or three OFDM symbols, wherein said indexes are determined according to the ratio n l i ' ' / n 0 ' when the PHICH is transmitted through one or three OFDM symbols, and wherein said indexes are determined according to the ratio n l i ' ' / n 1 ' when the PHICH is transmitted through two OFDM symbols and the first PHICH group is started from the second OFDM symbol, where the index l i ' = 0, if the PHICH is transmitted through one OFDM symbol, where the index l i ' = ( ⌊ m ' / 2 ⌋ + i + 1 ) m o d 2, m ' denoting an index of the PHICH group including the PHICH, if the PHICH is transmitted through two OFDM symbols, and where the index l i ' = i , if the PHICH is transmitted through three OFDM symbols, available resource element groups being resource element groups which can be used for PHICH transmission in the respective OFDM symbol, and • mapping the PHICH to the OFDM symbols according to the determined indexes.