Implementing LoRa MIMO System for Internet of Things

TL;DR

This paper proposes a novel LoRa MIMO system utilizing frequency division multiplexing and orthogonal CSS modulation to enhance IoT throughput, addressing bandwidth limitations with a new spatial multiplexing approach.

Contribution

Introduces a LoRa MIMO system using FDM and orthogonal CSS modulation, enabling higher throughput for IoT applications beyond traditional LoRa capabilities.

Findings

Effective spatial multiplexing with minimal channel correlation.

Enhanced throughput demonstrated on test hardware.

Resource consumption analysis of the proposed system.

Abstract

Bandwidth constraints limit LoRa implementations. Contemporary IoT applications require higher throughput than that provided by LoRa. This work introduces a LoRa Multiple Input Multiple Output (MIMO) system and a spatial multiplexing algorithm to address LoRa's bandwidth limitation. The transceivers in the proposed approach modulate the signals on distinct frequencies of the same LoRa band. A Frequency Division Multiplexing (FDM) method is used at the transmitters to provide a wider MIMO channel. Unlike conventional Orthogonal Frequency Division Multiplexing (OFDM) techniques, this work exploits the orthogonality of the LoRa signals facilitated by its proprietary Chirp Spread Spectrum (CSS) modulation to perform an OFDM in the proposed LoRa MIMO system. By varying the Spreading Factor (SF) and bandwidth of LoRa signals, orthogonal signals can transmit on the same frequency irrespective of the FDM. Even though the channel correlation is minimal for different spreading factors and bandwidths, different Carrier Frequencies (CF) ensure the signals do not overlap and provide additional degrees of freedom. This work assesses the proposed model's performance and conducts an extensive analysis to provide an overview of resources consumed by the proposed system. Finally, this work provides the detailed results of a thorough evaluation of the model on test hardware.