DSN: Enabling Lightweight Coordination between Partially Overlapped Channels in Wireless LANs

Partially overlapped channels (POCs) have been studied recently to improve network performance. However, the current OFDM-based 802.11 system is designed for co-channel communication, and does not support communication over POCs. Thus the coordination between POCs imposes a new challenge to WLANs. In this paper, we present DSN (Data Symbol Nulling), a novel communication strategy that leverages the pattern of data symbols (null or non-null), rather than the actual data symbol value, to convey lightweight control information (or sequences of binary bits). The receiver whose channel is partially overlapped with the sender, interprets thus-transmitted messages by detecting the energy of received data symbols, the minimum resource units in OFDM. A key principle of DSN is that the newly designed communication strategy does not sacrifice original data throughput. Our extensive results validate communication over POCs, and show that lightweight control information can be delivered with close to 100% accuracy. Further, based on this communication paradigm, we propose DSN-MAC, an efficient coordination scheme between POCs in WLANs. The detailed simulation results show that DSN-MAC can substantially improve overall network throughput.