Modern Wi-Fi networks are trending towards using a wider channel bandwidth to achieve high physical layer data rate. The wide channel band experiences fluctuations across the different frequencies, causing diversity in the frequency domain. Frequency-aware Wi-Fi protocols exploit this frequency diversity and consequently achieve high wireless capacity. However, most of the existing works have not considered quality-of-service (QoS) issues. In this paper, we present a new Wi-Fi protocol called QoS-Fi, that provides QoS for the mobile users in the frequency aware Wi-Fi network. QoS-Fi dynamically assigns orthogonal frequency division multiplexing (OFDM) subchannels for heterogeneous mobile users to meet the QoS demands. To achieve this goal, we apply an OFDM-based variable-length Bloom filter (VBF) that synergistically integrates the channel quality estimation and QoS channel coordination. To the best of our knowledge, this is the first work that employs QoS at the frequency domain for Wi-Fi networks. We study the impact of variable-length signatures in the aspect of throughput maximization and meeting the QoS requirements and further develop a decentralized QoS-aware channel-allocation algorithm that achieves sub-optimal performance. Our USRP/GNURadio-based experiments and trace-driven simulations show that QoS-Fi provides up to 1.39 × and 1.29 × throughput improvements compared to the legacy EDCA and well-known Knopp and Humblet’s and round robin (K&H/RR) scheduling, respectively in the QoS-regimes.
