INAV: Minimizing delay induced by DCF control packet losses in IEEE 802.11 to optimize throughput

IEEE 802.11 uses Distributed Coordination Function (DCF) as default channel access method which is based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) where all the nodes compete for the channel access. Based on this mechanism a node cannot transmit until the medium is free. Collision can occur if two or more stations within each other´s transmission range transmit simultaneously. To overcome this problem several solutions have been proposed, for instance Request To Send/Clear To Send (RTS/CTS) mechanism, through which the channel is reserved for a specified time period known as Network Allocation Vector (NAV). Although this mechanism provide all the nodes to share the medium fairly but it is observed that this mechanism can lead to bandwidth underutilization, especially in networks with higher packet delivery failure rates. In this paper, we propose Intimated Network Allocation Vector (INAV) - a modified version of existing NAV mechanism - which considerably reduce bandwidth underutilization in such networks. This modification works by exploiting the backing-off feature of neighbors of the communicating nodes. The proposed technique recovers more than 93% of idle waiting time for neighbors of the nodes that fail to complete the four way handshake of RTS/CTS.