Multi-User TWT Negotiation Mechanism Based On IEEE 802.11 Power Save Mode

In recent years, Wireless Local Area Networking (WLAN) has been more and more widely used. With the rapidly development of wireless communication technology, people are served with much better networking service. However, the better networking service means more frequently using wireless devices, such as smart phone, panel computer and notebook computer etc. To cope with mobility, these devices are generally powered with battery. Besides improving battery by manufacturers, it is necessary to improve the mechanism of IEEE 802.11 standard on power management. Therefore, power management has become a great concern in the industry. More and more scholars and researchers gradually concentrate on how to design and improve protocols.It has specified in IEEE 802.11 standard that STAs are allowed to enter power save mode, that is PSM mechanism. STAs in power save mode are able to maintain doze state as long as there is no transmission for a while to consume extremely low power. Data destined to doze STAs are buffered at AP. Doze STAs periodically wake up to receive beacon frame which is broadcasted by AP to check whether there are buffered data destined to themselves.Once beacon indicates AP buffers their data, STAs maintain awake to retrieve the data, while in other circumstance, STAs enter doze state.This paper summarizes key MAC layer technology in IEEE 802.11 standard and lays stress on the analysis of power management function. Particularly, the procedure of PSM mechanism is demonstrated in detail. It is obviously the background traffic has great impact on PSM mechanism. Hence, as long as distinguishing foreground traffic and background traffic, it is able to significantly improve power consumption. Moreover,in this paper, TWT mechanism in IEEE 802.11 ah standard has been depicted. With the introduction of TWT mechanism into PSM mechanism, it is effectively to improve power conservation.So far, researches over power management are focused on the situation of unicast TIM beacon period. On the contrary, there is lack of concentration on the circumstance of broadcast and multicast DTIM beacon period. This paper aims at broadcast and multicast services and proposes the multi-user TWT negotiation mechanism. In addition, the procedure of frames exchange and the design of frames format have been demonstrated. By means of the establishment of mathematical model with Markov chain, analysis of power consumption has been conducted theoretically. Finally, the simulation result from Matlab indicates that.comparing with traditional PSM mechanism, it is effectively to reduce power consumption when adopting TWT mechanism. What's more, the multi-user TWY negotiation mechanism not only can be used in power management, but also in the other circumstance that requires AP to schedule STAs.