Energy Consumption Analysis for Continuous Phase Modulation in Smart-Grid Internet of Things of beyond 5G

TL;DR

This work addresses energy efficiency in SG-IoT wireless sensor networks by developing a realistic EC model that integrates circuit-level and transmission energy with ARQ-based retransmissions. It analyzes CPM as a low-EC modulation, detailing its signal structure, key parameters ($M$, $h$, $N$, $g(t)$), and the forward/reverse energy balance that determines $E_b$ through $E_b = \frac{N_{re}(E_{FW} + E_{RV})}{L}$. Comparative results show CPM variants with REC, RC, and GMSK pulses outperform OQPSK and 16QAM in most regimes, with optimal energy loss minimized at moderate SNRs around $\gamma \approx 8$ dB for CPM. The study also highlights the practical implications for SG-IoT design in beyond-5G/6G, recommending CPM with simple pulse shapes to exploit constant-envelope advantages and reduce PA nonlinearity effects. Overall, CPM-based modulation emerges as a promising strategy for energy-constrained SG-IoT deployments.

Abstract

Wireless sensor network (WSN) underpinning the smart-grid Internet of Things (SG-IoT) has been a popular research topic in recent years due to its great potential for enabling a wide range of important applications. However, the energy consumption (EC) characteristic of sensor nodes is a key factor that affects the operational performance (e.g., lifetime of sensors) and the total cost of ownership of WSNs. In this paper, to find the modulation techniques suitable for WSNs, we investigate the EC characteristic of continuous phase modulation (CPM), which is an attractive modulation scheme candidate for WSNs because of its constant envelope property. We first develop an EC model for the sensor nodes of WSNs by considering the circuits and a typical communication protocol that relies on automatic repeat request (ARQ)-based retransmissions to ensure successful data delivery. Then, we use this model to analyze the EC characteristic of CPM under various configurations of modulation parameters. Furthermore, we compare the EC characteristic of CPM with that of other representative modulation schemes, such as offset quadrature phase-shift keying (OQPSK) and quadrature amplitude modulation (QAM), which are commonly used in communication protocols of WSNs. Our analysis and simulation results provide insights into the EC characteristics of multiple modulation schemes in the context of WSNs; thus, they are beneficial for designing energy-efficient SG-IoT in the beyond-5G (B5G) and the 6G era.

Figures (7)

• Figure 1: Physical layer packet structure.
• Figure 2: The communication modules and the corresponding power consumption model of a point-to-point wireless communication system.
• Figure 3: A typical power consumption model of the RF signal processing unit of a point-to-point wireless communication system.
• Figure 4: The relationship between the EC per successfully transmitted bit ($E_b$) and the received SNR ($\gamma$) for OQPSK, 16QAM, and the CPM signals with different pulse shaping functions (REC, RC, and GMSK), while assuming $M =16$ and $N=3$ for the three CPM waveforms, as well as $d = 10$ m and the AWGN channel for all the modulation schemes considered.
• Figure 5: The relationship between the EC per successfully transmitted bit ($E_b$) and the communication distance ($d$) for OQPSK, 16QAM, and the CPM signals with different pulse shaping functions (REC, RC, and GMSK) over the AWGN channel, while assuming $M =16$, $N=3$ and $\gamma = 8$ dB for the three CPM waveforms, as well as $\gamma = 15$ dB for OQPSK and 16QAM signals.