Message in Message for Improved LoRaWAN Capacity

Caillouet

2022 IEEE 33rd Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

2022

Self Cite

This paper considers a LoRaWAN cell in which devices access the channel using the unslotted ALOHA protocol. We propose a model of this access method that combines the effects of collisions with channel fading, by which reception may get buried in noise. Unlike the existing models of LoRaWAN, our model takes into account the frame arrival timing: it distinguishes, on the one hand, the interference created by earlier transmissions with respect to the frame of interest, and on the other hand, the interference by the frames arriving later on.From the results of the model, we draw three observations regarding the improvement of Packet Delivery Ratio (PDR). First, it puts back under the spotlight the often overlooked fact that repeating frames is always beneficial when the desired PDR is above 60%, even though the extra packet transmissions create more collisions. Second, as soon as the node density becomes notable and collisions have a similar impact on losses as attenuation, adding a smaller spreading factor SF6 modulation into the cell list of transmission parameters allows increasing the coverage range. Third, the model shows that cell capacity sometimes grows with the distance to the gateway or with decreased node transmission power, a trend seldom observed in wireless networks.

“…This model extends the model P P P ⌃ (v j ) = e vj P P P 0 (v j ) in which packet reception is conditioned on the empty channel when a frame arrives [8].…”

Section: F Pdr Considering Earlier Interferencementioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: F Pdr Considering Earlier Interferencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Frame Arrival Timing in LoRaWAN: Capacity Increase With Repeated Transmissions and More Channel Attenuation

Caillouet

2022 IEEE 33rd Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

2022

Self Cite

“…However, in reality in LoRaWAN, a small overlap between the end of a transmission and the start of the next frame preamble does not always prevent receiver locking on the second frame, whereas the physical layer robustness to noise and interference also allows successful reception of the first frame. Collisions due to ALOHA access are a major cause of packet loss, even if the CSS modulation makes transmissions somewhat robust to interference so they may survive overlapping transmissions leading to the well known capture effect [4], [17], [18], [19], [20].…”

Section: Related Workmentioning

confidence: 99%

Performance of Unslotted ALOHA With Capture and Multiple Collisions in LoRaWAN

Caillouet

IEEE Internet Things J.

2023

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This paper explores the capacity limits and the tradeoff between the antagonistic means of enabling reliable data delivery in a loaded LoRaWAN cell. In fact, channel attenuation and variability call for robust transmission settings but the associated load increase causes more collisions between frames. In addition to the physical layer parameters of the LoRa modulation, this paper considers the benefits and tuning of inter-packet Error Correction Codes (ECC), which also trades transmission redundancy for reliability. We thus start by proposing a refined Packet Delivery Ratio (PDR) model that improves the ones found in the literature in that, first, it takes into account the dependency between overcoming ambient noise and dominating colliding frames, and second, it considers the sum of interference powers when multiple colliding frames are present, even if the interference preexists. Moreover, the model extends to the case of a gateway with receiver diversity. In a second step, the model allows to set out the level of redundancy at which ECC is the most effective without hindering capacity: a coding rate of one third. When this is fixed, it allows to define the transmission parameters allocation within a cell and thus the size of the cell. We finally develop an ad-hoc Python discrete-event simulator, freely accessible, to complement the model for assessing the effect of inter-SF and near-far interference and to show the benefits of power control in this respect.

Range and Capacity of LoRa 2.4 GHz

Reyhane

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering

2023

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LoRa 2.4 GHz is a new variant of LoRa networks that uses the 2.4 GHz ISM band, different from the standard 868 MHz LoRa version. The LoRa physical layer takes advantage of a Chirp Spreading Spectrum (CSS) modulation with robust signals for transmission over long distances. While the standard LoRa in the 868 MHz band covers a range of 5-10 km, the actual capacity and range of LoRa 2.4 GHz are still not yet fully investigated. A shorter range is expected with the higher carrier frequency and an increased bandwidth. However, the wider bandwidth allows for the transmission of larger frames and a shorter airtime. In this study, we evaluate the coverage range and capacity of LoRa 2.4 GHz through precise simulations, taking into account a path loss model tailored for urban environments and frequencies over 2 GHz. We also take into account the effect of Rician or Rayleigh fading, as well as collisions in low and high load traffic conditions. The results show a maximum range of 1.1 km and capacity around 310 nodes for low traffic and the case in which each node in the network benefits from a minimum 60% Packet Delivery Ratio (PDR). This range drops to 700 m when the target PDR increases to 90%, accommodating 120 nodes. Under the assumption of Rayleigh fading and for the target PDR of 60 % and heavy load, the range attains 350 m with capacity of 30 nodes, and it drops to 120 m for the 90% target PDR.