Collision Resolution Protocol for Delay and Energy Efficient LoRa Networks

Abstract

Future 5G and Internet of Things (IoT) applications will heavily rely on long-range communication technologies such as low-power wireless area networks (LPWANs). In particular, LoRaWAN built on LoRa physical layer is gathering increasing interests, both from academia and industries, for enabling low-cost energy efficient IoT wireless sensor networks for, e.g., environmental monitoring over wide areas. While its communication range may go up to 20 kilometers, the achievable bit rates in LoRaWAN are limited to a few kilobits per second. In the event of collisions, the perceived rate is further reduced due to packet loss and retransmissions. Firstly, to alleviate the harmful impacts of collisions, we propose a decoding algorithm that enables to resolve several superposed LoRa signals. Our proposed method exploits the slight desynchronization of superposed signals and specific features of LoRa physical layer. Secondly, we design a full MAC protocol enabling collision resolution. The simulation results demonstrate that the proposed method outperforms conventional LoRaWAN jointly in terms of system throughput, energy efficiency as well as delay. These results show that our scheme is well suited for 5G and IoT systems, as one of their major goals is to provide the best trade-off among these performance objectives.

Throughput of distributed queueing-based LoRa for long-distance communication

“…• Some device's data transmission would interfere with the FBP reception of other devices, for example, in PP2, the FBP reception at ED2 is interfered by the transmitted signal of ED1. If the distance between ED1 and 2 is far enough, FBP still can be correctly decoded due to the capture effect [24]. However, if ED1 is close to ED2, correct decoding of FBP is obstructed.…”

Unsupervised Learning Clustering and Dynamic Transmission Scheduling for Efficient Dense LoRaWAN Networks

“…This is to retain the practicality of simulations given the considered high number of nodes. R ch in constraint (14), is the retransmission of lost packets due to bad channel condition for nodes n i located at distances further than d 0 from the GW.…”

“…This led to the strive of a number of research bodies and industrial organisations to challenge the efficiency of LoRaWAN. For example, Rachkidy et al [14], proposed a collision resolution technique that allows LoRa gateway to decode the collided and hence, corrupted received packets. While Liao et al [15], introduced a multi-hop based concurrent transmission technique in order to mitigate the probability of simultaneous packets transmissions of LoRa nodes.…”

“…Based on that, clusters with less SF reliability off-load traffic to clusters with higher SF reliability via multi-hop relay. Although, the collision rate has been enhanced in the aforementioned schemes [14]- [16], this comes at the expense of compromising the transmission delay or the energy consumption. Hence, in this paper, the aim of the work is to reduce the packet collision rate in LoRaWAN while maintaining relatively low transmission delay and energy consumption.…”

LoRaWAN: State of the Art, Challenges, Protocols and Research Issues

“…CR-MAC Protocol outperforms the conventional LoRaWAN protocol in terms of throughput, energy consumption, and delay. A comparison of both the protocols can be carried out by using the simulator which is designed in Perl [28]. Simulation results showed that LoRaWAN gives the throughput 40% while CR-MAC protocols reach its throughput to 58 %, 78%, and 83% by using the two, four, and eight slots, respectively.…”