Core Concepts
This survey presents a comprehensive review of prior works that employ contention-based and contention-free protocols in IoT networks with one or more dedicated energy sources to deliver energy and/or data.
Abstract
This survey provides a comprehensive review of channel access protocols designed for IoT networks with one or more dedicated energy sources. It covers both contention-based and contention-free protocols, highlighting the key issues and challenges addressed by prior works, as well as providing a qualitative comparison of these works.
The survey first outlines the typical network architectures and time slot structures used in prior works. It then discusses contention-based protocols, namely Aloha and CSMA, and how they are used to minimize collisions and consider the energy availability of devices. The survey then covers contention-free protocols, including polling, TDMA, and NOMA, and how they are used to optimize objectives such as sum-rate, fairness, and age of information.
The key issues addressed by prior works include:
- Determining the optimal frame size or number of time slots for energy delivery and data transmission
- Minimizing collisions through techniques like successive interference cancellation (SIC) and power control
- Ensuring fairness in terms of throughput or energy delivery
- Optimizing the trade-off between energy delivery and data transmission
- Addressing the doubly near-far problem where devices far from the energy source have low energy and low data rate
The survey also identifies gaps in the literature and presents a list of future research directions, including the use of intelligent reflective surfaces, predict-and-optimize frameworks, and graphical neural networks.
Stats
"Many Internet of Things (IoT) networks with Radio Frequency (RF) powered devices operate over a shared medium."
"Devices must first harvest RF energy in order to transmit or/and receive data."
"RF sources can mainly be classified into two types: ambient and dedicated."
"Dedicated RF sources are either co-located with an Access Point (AP), so called Hybrid Access Point (HAP), or deployed strategically for the purpose of charging devices; these sources are also called power beacons or stations."
Quotes
"RF-energy harvesting efficiency is non-linear, and it is a function of the received power."
"A key issue is ensuring an HAP uses a transmit power that yields the highest energy conversion efficiency."
"A key goal is to ensure all devices have a fair throughput or to optimize the worst data rate."