The modulation and coding scheme (MCS) 0, 7, 8, and 15 in AWK 802.11n products use two antennas to transmit data. The TX power specified is the maximum power we can measure in these devices while transmitting via 2 antennas.
The difference between MCS 0/7 and MCS 8/15 is the signal modulation and coding rates. MCS 0/8 modulation and coding rate are BPSK and 1/2 respectively while MCS 7/15 modulation and coding rate are 64-QAM and 5/6. That is,
- MCS 0/7 transfer the same data using 2 antennas (1 spatial stream)
- MCS 8/15 transfer different data using 2 antennas (2 spatial steams)
The transmission rate of MCS 8 is double that of MCS 0 and the transmission rate of MCS 15 is double that of MCS 7. And, the TX power of MCS 0 and MCS 8 is the same. Likewise, the TX power of MCS 7 and MCS 15 is the same.