چکیده:
LoRaWAN is one of the new and updated standards for IoT applications. However, the expected high density of peripheral devices for each gateway, and the absence of an operative synchronization mechanism between the gateway and peripherals, all of which challenges the networks scalability. In this paper, we propose to normalize the communication of LoRaWAN networks using a Reservation-ALOHA (R-ALOHA) instead of the standard ALOHA approach used by LoRa. The implementation is a library package placed on top of the standard LoRaWAN; thus, no modification in pre-existing LoRaWAN structure and libraries is required. Our proposed approach is based on a distributed synchronization service that is suitable for low-cost IoT end-nodes. R-ALOHA LoRaWAN gives better performance in comparison with the previous models; Pure-ALOHA LoRaWAN, Slotted-ALOHA LoRaWAN, and TDMA LoRaWAN. It significantly improves the performance of network regarding the probability of collision, the maximum throughput, and the maximum duty cycle.
خلاصه ماشینی:
R-ALOHA allows a large number of stations with irregular traffic to reserve slots to transmit their frames in future cycles.
In S-ALOHA systems, that is used widely in local wireless communications, the channel actual time is divided into slots, and each terminal is permitted to transmit packets only at the start of a slot (Polonelli et al.
For TDMA LoRaWAN, all the nodes that has data ready to be sent have to be synchronized and the transmission can only start at the beginning of each time slot.
(Lavric & Petrariu, 2018) LoRaWAN communication protocol original stack consists of three main layers; the physical layer, the MAC layer, and the application layer (Sanchez-Iborra et al.
Situation of five nodes and five slot reservation frames Our proposed model aimed to normalize and improve the communication of LoRaWAN networks using R-ALOHA instead of the standard ALOHA approach used by LoRa. The implementation of our model is done by using a library package placed on top of the standard LoRaWAN; thus, no modification in pre-existing LoRaWAN structure and libraries is (View the image of this page)required.
By applying R-ALOHA on LoRaWAN networks the communication between the nodes will take two modes: (1) the ALOHA mode that is responsible for slots reservation.
This proposed R-ALOHA model allows a large number of nodes with infrequent traffic flow to reserve slots for transmitting their data frames in the upcoming cycles.
number of end-devices Figure 5 presents results for the R-ALOHA network models that measure the maximum throughput with the increasing of the number of nodes.