Abstract
The Wi-Fi Direct standard for direct device-to-device communication has been defined by the Wi-Fi Alliance. Wi-Fi Direct defines two types of devices: peer-to-peer (P2P) clients and P2P group owners (GO). A P2P GO acts as an access point, and P2P clients are associated with the P2P GO. Wi-Fi Direct defines a P2P power management for P2P GOs and clients. The P2P power management supports two types of power-saving protocols, Opportunistic Power Save (OppPS) and Notice of Absence (NoA). These protocols allow P2P GOs to be absent to save power. However, an absence period leads to higher delay for P2P clients. The number of CTWindows defined in the OppPS protocol during a beacon interval, which is a presence period in a P2P GO, is one. To reduce delay, we propose a temporary CTWindow to increase the number of CTWindows during the beacon interval. Furthermore, we propose the adaptive control of the number of temporary CTWindows based on the amount of traffic. Simulation results reveal that the proposed method reduces delay compared with the OppPS protocol in a high offered traffic state.
