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Energy-Aware Receiver-initiated MAC Protocol for Energy Harvesting IoT
Sohail Sarang, Praveen Kumar Donta, Dejan Vukobratović
TL;DR
Variable energy harvesting can leave IoT devices without enough power to operate, while some existing MAC strategies rely on stored energy alone. EARI-MAC adapts receiver duty cycle using both stored battery energy and current harvesting power. In simulation with measured solar data, it improved delivery and throughput and reduced receiver energy use compared with the two baselines.
Problem
Variable harvesting conditions can leave IoT devices without enough energy to operate, and stored-energy-only MAC strategies may not sustain receivers during prolonged low harvesting.
Source: §I · p. 1Method
EARI-MAC adjusts receiver duty cycle using stored battery energy and current harvesting power, with a weighting parameter controlling their relative contributions.
Source: A. Communication overview · p. 2, B. Energy-aware duty cycle adjustment · p. 2Results
PDR and network throughput improved by more than 10%; receiver energy consumption fell by 5.6% and 8.2%, and energy consumption per bit by 9.6% and 13.9%, versus QPPD-MAC and energy-unaware MAC, respectively.
Source: §IV · p. 5Takeaways & Limitations
The weighting parameter can help balance receiver energy consumption under varying harvesting conditions to achieve the desired application performance.
Source: §IV · p. 5
Abstract
from arXiv · showhide
Energy harvesting (EH) technology has emerged as a key approach for extending the operational autonomy of Internet of Things (IoT) devices. In this context, medium access control (MAC) protocols for EH-IoT make use of the harvested energy efficiently to enhance the application performance. However, many existing MAC protocols rely on stored energy the battery in devising energy-aware strategies, which can interrupt the device operation and hinder the execution of ongoing tasks in dynamic and low EH conditions. To address this, this paper presents an energy-aware receiver-initiated MAC protocol for EH-IoT devices, called EARI-MAC, that adjusts the duty cycle of the receiver device based on stored energy and current harvesting power using the mathematical formulation. This approach supports sustained receiver operation under low EH conditions and improved application performance when harvested energy is abundant. The performance of the EARI-MAC has been evaluated in simulation using the real solar data gathered in Novi Sad, for three consecutive days. The simulation results demonstrate that the EARI-MAC utilizes the available energy resources efficiently and improves the packet delivery ratio and network throughput by more than 10%, reduces the receiver energy consumption by 5.6% and 8.2% and energy consumption per bit by 9.6% and 13.9% compared with QPPD-MAC and energy-unaware MAC, respectively.
I. INTRODUCTION
Energy harvesting can reduce IoT devices’ dependence on batteries, but variable availability—especially during low-solar periods—can disrupt operation. EARI-MAC addresses limitations in existing approaches by adapting receiver duty cycle using both stored energy and current harvesting power.
I. INTRODUCTION
- During rainy days or other periods of low energy availability, IoT devices may lack enough harvested energy and stop working for long periods.Source: §I · p. 1
- Dynamic energy availability affects protocol decisions such as transmission scheduling, wake-up time, resource allocation, and synchronization.Source: §I · p. 1
- Prior approaches include stored-energy duty cycling and forecast-based adaptation, while reliance on stored energy alone can limit sustained operation during prolonged low harvesting.Source: §I · pp. 1–2
- EARI-MAC adjusts the receiver’s duty cycle using both stored battery energy and current harvesting power, and is evaluated against EH-aware and energy-unaware protocols.Source: §I · p. 2
A. Communication overview
EARI-MAC uses receiver-initiated communication: the receiver starts each cycle, selects among sender requests, and acknowledges the selected sender’s packet.
A. Communication overview
- At each cycle’s start, the receiver broadcasts a wake-up beacon, collects sender requests during a configurable interval, and selects the highest-priority request.Source: A. Communication overview · p. 2
- The receiver announces the selected sender in an Rx beacon; that sender transmits its packet while non-selected senders sleep and can contend again next cycle.Source: A. Communication overview · p. 2
- The communication overview is shown in Fig. 1.Source: Figure 1 · p. 2
B. Energy-aware duty cycle adjustment
EARI-MAC adapts receiver duty cycle to energy conditions by combining remaining battery energy and current harvesting power. Its parameterization also sets duty-cycle bounds and a battery threshold, then uses duty cycle and active time to calculate sleep time.
B. Energy-aware duty cycle adjustment
- The receiver adjusts duty cycle based on remaining energy and current harvesting power to support operation under varying harvesting conditions.Source: B. Energy-aware duty cycle adjustment · p. 2
- The weighting parameter α balances normalized remaining energy against normalized harvesting power, while Dmin and Dmax set the duty-cycle bounds.Source: B. Energy-aware duty cycle adjustment · p. 2
- A threshold of 10% of maximum battery capacity is applied to prevent complete battery depletion.Source: B. Energy-aware duty cycle adjustment · p. 2
- The computed duty cycle and active time are used to calculate receiver sleep time; harvesting power is normalized against a maximum measured reference.Source: B. Energy-aware duty cycle adjustment · p. 2
A. Experimental and simulation setup
The evaluation uses a single-hop GreenCastalia simulation with measured solar-harvesting data from Novi Sad over 72 consecutive hours. It compares EARI-MAC with QPPD-MAC and an energy-unaware receiver-initiated protocol.
A. Experimental and simulation setup
- The single-hop GreenCastalia simulations use solar irradiance measurements from Novi Sad, Serbia, collected from 5 to 8 January 2021, across 72 consecutive hours.Source: A. Experimental and simulation setup · p. 2, Figure 2 · p. 3
- The energy-unaware receiver-initiated protocol uses a fixed duty cycle of 0.5; the evaluation compares it with QPPD-MAC and EARI-MAC.Source: A. Experimental and simulation setup · p. 2
- Fig. 3 presents receiver energy level for a scenario with seven sender devices.Source: Figure 3 · p. 3
- The simulation models a TelosB device with a CC2420 radio and uses specified solar-cell and network parameters.Source: A. Experimental and simulation setup · p. 3
B. Results and discussion
EARI-MAC combines stored energy and current harvesting power to adjust receiver duty cycle, sustaining operation under low solar availability. It outperforms QPPD-MAC and energy-unaware MAC on packet delivery, throughput, and energy metrics in the reported simulations.
B. Results and discussion
- After the second day, receiver energy was 21.5% for EARI-MAC, 12.9% for QPPD-MAC, and 9.5% for energy-unaware MAC.The latter two receivers remained nonoperational for almost 7 and 10 hours, respectively, while EARI-MAC maintained sufficient energy to operate.Source: B. Results and discussion · p. 3
- With α = 0.8, EARI-MAC selected a duty-cycle weighting intended to sustain receiver operation and improve network performance.Larger α emphasizes stored energy; smaller α gives greater weight to current harvesting power.Source: B. Results and discussion · p. 3
- 100% PDR across 1–7 senders; at seven, QPPD-MAC and energy-unaware MAC fall to 90.4% and 86.1%, respectively.EARI-MAC’s PDR improvements are 9.6% and 13.9% versus those protocols, and its throughput is more than 10% higher across evaluated sender counts.Source: B. Results and discussion · pp. 3–4, Figure 6 · p. 4, Figure 7 · p. 4
- 5.6% and 8.2% lower receiver energy consumption versus QPPD-MAC and energy-unaware MAC, respectively.Energy consumption per bit is reduced by 9.6% and 13.9% versus those protocols, respectively.Source: Figure 8 · p. 4, Figure 9 · p. 4, B. Results and discussion · p. 4
IV. CONCLUSION AND FUTURE WORK
EARI-MAC adjusts receiver duty cycle using stored battery energy and current harvesting power, and simulations report improved delivery and throughput alongside reduced energy consumption. The conclusion also identifies duty-cycle weighting as a way to balance receiver energy use under varying harvesting conditions and names multiple energy-harvesting sources as future work.
- EARI-MAC adjusts receiver duty cycle based on stored battery energy and current harvesting power.Its performance was evaluated in simulation using locally collected solar data over 72 hours and compared with two other protocols.Source: §IV · p. 4
- PDR and network throughput improved by more than 10% compared to the other protocols.The reported reductions were 5.6% and 8.2% for receiver energy consumption, and 9.6% and 13.9% for energy consumption per bit, compared to QPPD-MAC and energy-unaware MAC, respectively.Source: §IV · p. 5
- The weighting parameter’s influence on receiver duty cycle was investigated as a way to balance receiver energy consumption under varying harvesting conditions.The stated aim is to achieve the desired application performance.Source: §IV · p. 5
- Future work will design and implement an energy-aware IoT MAC protocol incorporating multiple energy-harvesting sources.Source: §IV · p. 5