A method of transmitting a multiple input multiple output, MIMO, packet in a wireless local area network system, the method comprising: generating a physical layer convergence procedure protocol data unit, PPDU, including a first signal, SIG, field and at least one data field (530, 531, 532, 533); and transmitting the PPDU by using a single user multiple input multiple output, SU-MIMO, transmission scheme or a multi user, MU, -MIMO transmission scheme, wherein the first signal field includes a group ID sub-field, characterised in that the first signal field further includes a coding sub-field, and a modulation and coding scheme, MCS, sub-field, wherein the group ID sub-field indicates whether the PPDU is transmitted by using the SU-MIMO transmission scheme or the MU-MIMO transmission scheme, wherein the coding sub-field indicates one encoding scheme applied to one data field when the PPDU is transmitted by using the SU-MIMO transmission scheme, wherein the coding sub-field indicates an encoding scheme applied to a data field to be transmitted to a first receiving station when the PPDU is transmitted by using the MU-MIMO transmission scheme, wherein the MCS sub-field indicates an encoding scheme applied to respective data fields (532, 533) to be transmitted to a second receiving station, a third receiving station, and a fourth receiving station when the PPDU is transmitted by using the MU-MIMO transmission scheme, wherein the encoding scheme is a binary convolution coding, BCC, encoding scheme or a low density parity check, LDPC, encoding scheme, wherein the MCS sub-field indicates one MCS index for decoding one data field when the PPDU is transmitted by using the SU-MIMO transmission scheme. generating a physical layer convergence procedure protocol data unit, PPDU, including a first signal, SIG, field and at least one data field (530, 531, 532, 533); and transmitting the PPDU by using a single user multiple input multiple output, SU-MIMO, transmission scheme or a multi user, MU, -MIMO transmission scheme, wherein the first signal field includes a group ID sub-field, characterised in that the first signal field further includes a coding sub-field, and a modulation and coding scheme, MCS, sub-field, wherein the group ID sub-field indicates whether the PPDU is transmitted by using the SU-MIMO transmission scheme or the MU-MIMO transmission scheme, wherein the coding sub-field indicates one encoding scheme applied to one data field when the PPDU is transmitted by using the SU-MIMO transmission scheme, wherein the coding sub-field indicates an encoding scheme applied to a data field to be transmitted to a first receiving station when the PPDU is transmitted by using the MU-MIMO transmission scheme, wherein the MCS sub-field indicates an encoding scheme applied to respective data fields (532, 533) to be transmitted to a second receiving station, a third receiving station, and a fourth receiving station when the PPDU is transmitted by using the MU-MIMO transmission scheme, wherein the encoding scheme is a binary convolution coding, BCC, encoding scheme or a low density parity check, LDPC, encoding scheme, wherein the MCS sub-field indicates one MCS index for decoding one data field when the PPDU is transmitted by using the SU-MIMO transmission scheme.