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. 2020 Jul 24;20(15):4123.
doi: 10.3390/s20154123.

LoRa Traffic Generator Based on Software Defined Radio Technology for LoRa Modulation Orthogonality Analysis: Empirical and Experimental Evaluation

Alexandru Lavric  1 , Adrian I Petrariu  1 , Eugen Coca  1 , Valentin Popa  1
Affiliations

LoRa Traffic Generator Based on Software Defined Radio Technology for LoRa Modulation Orthogonality Analysis: Empirical and Experimental Evaluation

Alexandru Lavric et al. Sensors (Basel). .

Abstract

The digital revolution has changed the way we implement and use connected devices and systems by offering Internet communication capabilities to simple objects around us. The growth of information technologies, together with the concept of the Internet of Things (IoT), exponentially amplified the connectivity capabilities of devices. Up to this moment, the Long Range (LoRa) communication technology has been regarded as the perfect candidate, created to solve the issues of the IoT concept, such as scalability and the possibility of integrating a large number of sensors. The goal of this paper is to present an analysis of the communication collisions that occur through the evaluation of performance level in various scenarios for the LoRa technology. The first part addresses an empirical evaluation and the second part presents the development and validation of a LoRa traffic generator. The findings suggest that even if the packet payload increases, the communication resistance to interferences is not drastically affected, as one may expect. These results are analyzed by using a novel Software Defined Radio (SDR) technology LoRa traffic generator, that ensures a high-performance level in terms of generating a large LoRa traffic volume. Despite the use of orthogonal variable spreading factor technique, within the same communication channel, the collisions between LoRa packets may dramatically decrease the communication performance level.

Keywords: LoRa modulation; LoRaWAN; scalability; software defined radio; traffic generator.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
IoT communication protocols. Viable communication protocols that can be integrated into the Internet of Things (IoT) concept.
Figure 2
Figure 2
LoRaWAN architecture. It consists of sensors, gateways, a network server to allow user applications to access field data and a server for the application’s data.
Figure 3
Figure 3
Bit Error Rate (BER) parameter for SF12, bandwidth (BW) = 125 kHz. The figure depicts the BER parameter when the SF12 spreading factor is used for a 125 kHz channel bandwidth. One can observe a decrease in performance.
Figure 4
Figure 4
The analysis of performance based on SF, BW and packet payload variation. The SF is varied from SF6 to SF12 and the bandwidths analyzed are 125 kHz and 500 kHz, respectively. In the evaluation scenarios, the payload is varied from 1 byte to 243 bytes.
Figure 4
Figure 4
The analysis of performance based on SF, BW and packet payload variation. The SF is varied from SF6 to SF12 and the bandwidths analyzed are 125 kHz and 500 kHz, respectively. In the evaluation scenarios, the payload is varied from 1 byte to 243 bytes.
Figure 5
Figure 5
The analysis of performance for SF8 when using a packet payload of 60 bytes. The SF is varied from SF8 to SF10, and the analyzed bandwidth is 500 kHz.
Figure 5
Figure 5
The analysis of performance for SF8 when using a packet payload of 60 bytes. The SF is varied from SF8 to SF10, and the analyzed bandwidth is 500 kHz.
Figure 6
Figure 6
BER obtained by varying the payload size while maintaining the same BW value. The payload was varied from 60 bytes to 120 bytes and 180 bytes.
Figure 7
Figure 7
BER curves for a specific SF obtained by varying the BW size from 125 kHz to 250 kHz and 500 kHz, respectively, while maintaining the same payload size 120 bytes.
Figure 8
Figure 8
LoRa traffic generator by integrating Software Defined Radio (SDR) technology. The integrated communication mechanism can generate a high volume of data with the help of LoRa packet transmissions.
Figure 9
Figure 9
LoRaWAN gateway. The gateway integrates a Raspberry PI 3B+ and the iC880A concentrator that allows the simultaneous communication on eight channels (as stated in the LoRaWAN specifications).
Figure 10
Figure 10
Performance evaluation test setup. (a) presents the test setup configuration. (b) depicts the traffic generator that has been realized by using two SDRs of a LimeSDR type and the host PC, which runs the application. (c) presents the measurement equipment.
Figure 10
Figure 10
Performance evaluation test setup. (a) presents the test setup configuration. (b) depicts the traffic generator that has been realized by using two SDRs of a LimeSDR type and the host PC, which runs the application. (c) presents the measurement equipment.
Figure 11
Figure 11
LoRa traffic generator, spectrum. It can be observed that the LoRa sensors communicate on the same channel as the LoRa traffic generator. Thus, the LoRa traffic generator can obtain LoRa concurrent transmissions so that a high number (e.g., thousands) of nodes can be emulated.
Figure 12
Figure 12
LoRa packet spectrum. The packet created by the LoRa traffic generator respects the LoRaWAN specifications and is received correctly by the gateway module.
Figure 13
Figure 13
LoRa packet spectrum.
Figure 14
Figure 14
LoRa traffic generator results.
See this image and copyright information in PMC

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