2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)
LoRaWAN is a promising low power long range wireless communications technology for the Internet of Things. An important feature of LoRaWAN gateways is related to so-called capture effect: under some conditions the gateway may correctly receive a frame even if it overlaps with other ones. In this paper, we develop a pioneering mathematical model of a LoRaWAN network which allows finding network capacity and transmission reliability taking into account the capture effect.
In order to meet the continuously increasing demands for high throughput in wireless networks, IEEE 802 LAN/MAN Standard Committee is developing IEEE 802.11ax: a new amendment for the Wi-Fi standard. This amendment provides various ways to improve the efficiency of Wi-Fi. The most revolutionary one is OFDMA. Apart from obvious advantages, such as decreasing overhead for short packet transmission at high rates and improving robustness to frequency selective interference, being used for uplink transmission, OFDMA can increase power spectral density and, consequently, user data rates. However, the gain of OFDMA mainly depends on the resource scheduling between users. The peculiarities of OFDMA implementation in Wi-Fi completely change properties of classic schedulers used in other OFDMA systems, e.g. LTE. In the paper, we consider the usage of OFDMA in Wi-Fi for uplink transmission. We study peculiarities of OFDMA in Wi-Fi, adapt classic schedulers to Wi-Fi, explaining why they do not perform well. Finally we develop a novel scheduler, MUTAX, and evaluate its performance with simulation.
In order to meet the rising demands for the Internet of Things technologies, Wi-Fi community has developed Wi-Fi HaLow. It extends Wi-Fi with new functionality supporting high number of autonomous devices with various power capabilities and traffic patterns. In the paper, we study the cooperation of such new mechanisms as TIM Segmentation and Restricted Access Window. TIM Segmentation reduces energy consumption for low-power devices retrieving data from the Access Point, while Restricted Access Window reduces contention and allows the Access Point to protect stations with different capabilities from interfering each other. We consider joint usage of these mechanisms in a heterogeneous network with a high number of low-power stations with rare traffic and several powered stations with saturated traffic. Specifically, for TIM Segmentation and Restricted Access Window we develop a simple and fairly accurate mathematical method to set up the parameters of the mechanisms in order to improve performance for both types of stations, i.e. to reduce power consumption for low-power stations and to increase throughput for the other ones.