Energy-efficient MAC protocol for wireless LANs with WiFi sensors

More and more mobile computing devices such as smartphones with limited battery power are being used in IEEE 802.11 wireless LANs, and WiFi sensors with very limited battery power are expected to get Internet access through wireless LANs in the near future. We propose an efficient MAC (Medium Access Control) protocol so that WiFi sensors and mobile devices are connected to APs (Access Points) in IEEE 802.11 wireless LANs in an energy-efficient manner.

Testing Off-the-Shelf Optical Wireless LANs for Smart City Environments

Optical wireless LANs (OWLs) constitute an emerging networking paradigm for indoor scenarios’ fit to different smart cities’ fields of applications. Commercial products employing this technology have been made available on the market in recent years. In this work, we investigate, through a set of indoor communication experiments based on commercially available products, how different environmental and usage modes affect the performance of the system, addressing the presence of multiple users, the position and mobility of the mobile devices, the handover among adjacent cells and the effect of background lighting. Our finding shows that the system is quite robust with respect to the variation of operational conditions. We show that, in most conditions, the links can reliably sustain a stable throughput, achieving at least 50% of the throughput achieved with using the maximum light intensity of the transmitting lamp, while they are affected in a very mild way by factors like position and height of the mobile device, and virtually unaffected by variations in the background light.

Device-Free Indoor Location Estimation System Using Commodity Wireless LANs

In recent years, since the propagation channel characteristics have been effectively used for applications such as motion sensing, position detection, etc. A great deal of attention is attracted to channel sounding methods easy to utilize using low-cost devices. This paper presents a device-free indoor location estimation method using spatio-temporal features of radio propagation channels using the 2.4-GHz band 3-by-3 MIMO channel sounder developed using commodity wireless LANs. The measurement results demonstrated a reasonable performance of the proposed method with small number of antennas.