Abstract
A long-range wide area network (LoRaWAN) adapts the ALOHA network concept for channel access, resulting in packet collisions caused by intra- and inter-spreading factor (SF) interference. This leads to a high packet loss ratio. In LoRaWAN, each end device (ED) increments the SF after every two consecutive failed retransmissions, thus forcing the EDs to use a high SF. When numerous EDs switch to the highest SF, the network loses its advantage of orthogonality. Thus, the collision probability of the ED packets increases drastically. In this study, we propose two SF allocation schemes to enhance the packet success ratio by lowering the impact of interference. The first scheme, called the channel-adaptive SF recovery algorithm, increments or decrements the SF based on the retransmission of the ED packets, indicating the channel status in the network. The second approach allocates SF to EDs based on ED sensitivity during the initial deployment. These schemes are validated through extensive simulations by considering the channel interference in both confirmed and unconfirmed modes of LoRaWAN. Through simulation results, we show that the SFs have been adaptively applied to each ED, and the proposed schemes enhance the packet success delivery ratio as compared to the typical SF allocation schemes.
Highlights
A long-range wide area network (LoRaWAN) is a wireless technology designed for low-power wide area networks [1]
The performance analysis of the LoRaWAN under a realistic channel model and high-density urban area topology is presented in terms of success ratio (SR), μD, and μDack delays
We observed that the transmissions arriving at the GW with the same or different spreading factor (SF) could be correctly received, only when their respective signal-to-interference-plus-noise ratio (SINR) values are above a certain threshold
Summary
A long-range wide area network (LoRaWAN) is a wireless technology designed for low-power wide area networks [1]. Because many EDs switch to higher SFs, it causes an avalanche effect [4] To overcome this effect in the network, we propose a scheme called the channel-adaptive SF recovery that increments or decrements the SF based on the retransmission of the ED packets in the network. To overcome the impact of intra- or inter-SF interference in the LoRaWAN network, some of the approaches allocate SF according to the distances from the GW in unconfirmed mode [4,5,6,7] These SF allocation schemes are mainly based on the fixed-width SF rings ( known as ring-based approaches) such as equal distance-based [4], GW sensitivity-based [5,6], and signal-to-noise ratio (SNR)-based [7]. The experimental results and analysis of the proposed SF allocation schemes are presented in Section 5, while Section 6 concludes this paper
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