Charm: Exploiting Geographical Diversity through Coherent Combining in Low-Power Wide-Area Networks

Joint range extension and localization for low‐power wide‐area network

“…LoRa is able to change the SF according to the link quality and different orthogonal SFs can be supported to trade data rate for sensitivity within a fixed channel bandwidth. In the EU863‐870 ISM band, 3 channels of 125 kHz must be supported by any LoRa end device …”

“…LoRa range extension has been the focus of multiple research projects trying to increase the decoding capabilities at the gateway level for the uplink, while achieving a low power consumption by end devices . A system with a single antenna gateway that enables collaboration between end devices was proposed to overcome the challenges rising in high density deployment .…”

“…Moreover, the system uses spatial filtering techniques in order to achieve a higher SNR at the end device. While most contributions are towards improving the uplink, Snipe enhances both the uplink and downlink by using a Multiple‐Input Multiple‐Output (MIMO) design that respects the LoRa energy consumption restraints. Furthermore, MIMO support at the gateway provides low cost Angle of Arrival (AoA) and end device position estimation.…”

“…Moreover, by hosting the MIMO signal processing locally at the gateway, the proposed system allows combining coherently the signals from each one of the antennas elements indiscriminately. This contrasts with cloud‐based approaches that involve renting compute and storage nodes as well as providing links with large bandwidth …”

“…This contrasts with cloud-based approaches that involve renting compute and storage nodes as well as providing links with large bandwidth. 3 The rest of the paper is organized as follows: Section 2 reminds some basic LoRa principles. Section 3 presents the range extension problem and the approach to address it by leveraging coherent combining and spatial filtering.…”