TY - JOUR
T1 - On the LoRa Modulation for IoT
T2 - Preamble Designs for Channel Estimation With Single- and Multi-Chirp Transmission Strategies
AU - Kang, Jae Mo
N1 - Publisher Copyright:
© 2014 IEEE.
PY - 2024
Y1 - 2024
N2 - Long range (LoRa), a low power and wide area modulation scheme based on a chirp spread spectrum, is the most popular and widely adopted Internet of Things (IoT) technique. In LoRa, acquiring channel state information (CSI) is imperative for improving the system performance, but is a challenging task. In this article, we tackle the problem of preamble design for the CSI acquisition with LoRa modulation in a multiple access scenario with multiple transmitters and a receiver. The main contributions of this article are three-fold. First, we propose two novel and effective preamble transmission strategies: 1) single-chirp preamble transmission and 2) multi-chirp preamble transmission, both employing modulated up chirps. Second, we present how to optimize such preamble signals jointly with transmission power (for the former strategy) and combining coefficients (for the latter strategy) in the sense of minimizing total mean square error (MSE) in estimating the CSI of the whole links between the transmitters and the receiver under practical power constraints, adopting the linear minimum MSE (LMMSE) criterion. In addition, to gain more insights and further lower the design complexity, we investigate several special, yet important, scenarios. Lastly, we present extensive numerical results simulated in realistic propagation environments to substantiate the superiority and effectiveness of the proposed schemes. Also, we reveal new tradeoffs between the proposed single- and multi-chirp preamble transmission strategies in terms of performance and complexity.
AB - Long range (LoRa), a low power and wide area modulation scheme based on a chirp spread spectrum, is the most popular and widely adopted Internet of Things (IoT) technique. In LoRa, acquiring channel state information (CSI) is imperative for improving the system performance, but is a challenging task. In this article, we tackle the problem of preamble design for the CSI acquisition with LoRa modulation in a multiple access scenario with multiple transmitters and a receiver. The main contributions of this article are three-fold. First, we propose two novel and effective preamble transmission strategies: 1) single-chirp preamble transmission and 2) multi-chirp preamble transmission, both employing modulated up chirps. Second, we present how to optimize such preamble signals jointly with transmission power (for the former strategy) and combining coefficients (for the latter strategy) in the sense of minimizing total mean square error (MSE) in estimating the CSI of the whole links between the transmitters and the receiver under practical power constraints, adopting the linear minimum MSE (LMMSE) criterion. In addition, to gain more insights and further lower the design complexity, we investigate several special, yet important, scenarios. Lastly, we present extensive numerical results simulated in realistic propagation environments to substantiate the superiority and effectiveness of the proposed schemes. Also, we reveal new tradeoffs between the proposed single- and multi-chirp preamble transmission strategies in terms of performance and complexity.
KW - Channel estimation
KW - Internet of Things (IoT)
KW - chirp spread spectrum
KW - long range (LoRa)
KW - preamble design
KW - preamble transmission
UR - http://www.scopus.com/inward/record.url?scp=85184798039&partnerID=8YFLogxK
U2 - 10.1109/JIOT.2024.3363170
DO - 10.1109/JIOT.2024.3363170
M3 - Article
AN - SCOPUS:85184798039
SN - 2327-4662
VL - 11
SP - 27981
EP - 27993
JO - IEEE Internet of Things Journal
JF - IEEE Internet of Things Journal
IS - 17
ER -