Low-Overhead Control Channels in Wireless Networks

Low-latency, low-overhead and reliable control channels are essential to the efficient operation of wireless networks. However, control channels that utilize current in-band and out-of-band designs do not fully meet this requirement. In this paper, we design and implement Aileron, a novel control channel based on automatic modulation recognition that carries control frames over an OFDM(A) PHY by varying the modulation rate of the OFDM subcarriers. With Aileron, the control information is embedded into the modulation type, not as the actual symbol value. The thus-transmitted information can be received with little to no frame synchronization. We have evaluated Aileron using both extensive simulations and real-world measurements, and discovered that control frames can be transmitted with more than 80 percent accuracy using only 10 OFDM blocks on a channel with SNR of merely 10 dB. In order to demonstrate its applicability and efficiency in realistic networking scenarios, we also show how Aileron can be used in conjunction with a fine-grained channel access protocol to increase throughput under heterogeneous link conditions.