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Multi-Hop LoRa Networks Enabled by Concurrent Transmission
By : ȫ
Date : 2018-08-06
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Multi-Hop LoRa Networks Enabled by Concurrent Transmission

ABSTRACT In this paper, we strive to construct an efcient multi-hop network based on the sub-GHz lowpower
wide-area technology. Specically, we investigate the combination of LoRa, a physical-layer standard
that can provide several-kilometer outdoor coverage, and concurrent transmission (CT), a recently proposed
multi-hop protocol that can signicantly improve the network efciency. The main contributions of this paper
are threefold. 1) Since the CT enhances the network efciency by allowing synchronized packet collisions,
the performance of the physical-layer receiver under such packet collisions needs to be carefully examined
to ensure the network reliability. We rst extensively evaluate the LoRa receiver performance under CT to
verify that LoRa is compatible to CT. Specically, we nd that, due to the time-domain and frequencydomain
energy spreading effect, LoRa is robust to the packet collisions resulting from CT. 2) We further
nd the receiver performance under CT can be further improved by introducing timing offsets between the
relaying packets. In view of this, we propose a timing delay insertion method, the offset-CT method, that
adds random timing delay before the packets while preventing the timing offset from diverging over the
multi-hop network. 3) We conduct proof-of-concept experiments to demonstrate the feasibility of CT-based
LoRa multi-hop network and the performance improvement brought by the proposed offset-CT method.
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