Method and apparatus for transmitting plcp frame in wireless local area network system

An apparatus, comprising:

• at least one processor;
• at least one memory including computer program code, the memory and the computer program code configured to, working with the processor, cause the apparatus to perform at least the following:
• receive a Physical Layer Convergence Procedure (PLCP) Protocol Data Unit (PPDU), the PPDU comprising:
• a Legacy Signal (L-SIG) field including a first L-SIG symbol that is mapped onto a first binary phase shift keying (BPSK) constellation;
• a Very High Throughput Signal (VHT-SIG) field including a first VHT-SIG symbol and a second VHT-SIG symbol immediately after the first VHT-SIG symbol, the first VHT-SIG symbol being mapped onto the first BPSK constellation, and the second VHT-SIG symbol being mapped onto a second BPSK constellation and rotated by 90° counter-clockwise relative to the first VHT-SIG symbol;
• and
• a Very High Throughput Short Training Field (VHT-STF) field immediately after the VHT-SIG field,
• wherein the first VHT-SIG symbol includes an indicator indicating a Single User-Multiple Input Multiple Output (SU-MIMO) PPDU or a multi user-MIMO (MU-MIMO) PPDU, and the second VHT-SIG symbol includes a cyclic redundancy check (CRC) for the first VHT-SIG symbol and, at least a portion of, the second VHT-SIG symbol, and
• wherein the PPDU omits a High Throughput Signal (HT-SIG) field between the L-SIG field and the VHT-SIG field.