Energy-Efficient and Reliable IoT Access Without Radio Resource Reservation

Abstract

One of the major challenges for Internet-of-Things applications is that the existing cellular technologies do not support the uplink IoT traffic in an energy-efficient manner. There are two principal ways for serving the uplink IoT traffic: grant-based (i.e. scheduled) and grant-free (i.e. random access). Grant-based access provides fine-grained control of reliability and latency at the cost of energy consumption required for signaling. Grant-free access removes the signaling overhead at the cost of looser control of performance in terms of reliability and latency. However, a precise analysis of reliability, latency and energy performance of grant-free access (GFA) is largely missing. This article focuses on a GFA-type protocol, in which a device transmits several packet replicas, asynchronously with respect to the other devices. Using stochastic geometry, we derive closedform expressions for reliability, delay, and energy consumption, which can be used to identify the tradeoffs among these performance parameters. In order to improve the performance of the protocol, we develop a receiver that leverages the random timing and frequency offsets among the devices in order to facilitate resolution of collisions. This is complemented by a per-device adaptive scheme that controls the number of transmitted replicas. The evaluation confirms the validity of the analysis and the potential of the proposed solution, identifying operating regions in which GFA outperforms the grant-based access.

Deep Reinforcement Learning Driven Joint Dynamic TDD and RRC Connection Management Scheme in Massive IoT Networks

“…Recent studies on efficient energy consumption of IoT devices revolve around the network access of uplink IoT traffic [23]. With the development of grant-free transmission supporting sporadic generation of short packets, Azari et al [24] conduct a comparative analysis on grant-free and traditional grant-based transmission in terms of reliability and energy consumption. They investigate traffic load regimes at which IoT devices benefit from grant-free transmission in terms of energy efficiency.…”

mmWave Coverage Extension Using Reconfigurable Intelligent Surfaces in Indoor Dense Spaces

“…Compared to other common communication scenarios, energy saving in IDS is more important since power resources are limited. There is a significant amount of research devoted to minimizing the energy consumption of networks both in fixed [5][6][7] and wireless communications [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. With the commercialization of 5G technology, due to the above reasons, enhancing the coverage of the mmWave with the least amount of energy has become a critical problem that needs to be solved.…”