Users increasingly depend on WLAN for business and entertainment. However, they occasionally experience dead spots and high loss rates. We show that these problems can be addressed by exposing information readily available at the physical layer. We make the physical layer convey its confidence that a particular bit is 0 or 1 to the higher layers. Access points that hear the same transmission communicate their confidence values over the wired Ethernet and combine their information to correct faulty bits in a corrupted packet. A single receiver may also combine the confidence estimates from multiple faulty retransmissions to obtain a correct packet. We implement our design and evaluate it using GNU software radios. The results show that our approach reduces loss rate by up to 10x in comparison with the current approach, and significantly outperforms prior packet combining proposals.

High peak to average power ratio (PAR), a major drawback in single-input-single-output (SISO) systems using orthogonal frequency division multiplexing (OFDM), has already found many methods of reduction. The active channel extension (ACE) method reduces analog PAR by as much as 3.5 dB with no reduction in data rate by altering constellation points. We present an extension of this original method for PAR reduction for multi-input-multi-output (MIMO) systems in general. This new scheme, compatible with variable power allocation, minimizes PAR on each antenna in a similar manner as in the SISO system. It also supports any number of unique constellations and number of antennas by moving outer constellation points appropriately depending on the constellation for the particular channel and antenna. Simulations with 4 antennas at both transmitter and receiver show analog peak reductions of more than 3 dB overall for all 4 antennas.