# A Throughput and Energy Efficiency Scheme for Unlicensed Massive Machine Type Communications

## TL;DR

This paper investigates the throughput and energy efficiency of unlicensed machine type communications, considering interference, retransmissions, and optimization constraints to improve performance without harming licensed users.

## Contribution

It introduces a model analyzing unlicensed network performance with interference management, retransmission strategies, and constrained optimization, highlighting the importance of limiting transmissions.

## Key findings

- Optimal retransmission strategies improve energy efficiency.
- Interference from licensed users impacts unlicensed network throughput.
- Limited retransmissions provide benefits in energy and throughput performance.

## Abstract

In this paper the throughput and energy efficiency of an unlicensed machine type communications network is studied. If an outage event happens in the network, there is a possibility for packet retransmissions in order to obtain a lower error probability. The model consist of a network with two types of users, Licensed and unlicensed users. The licensed users allocated uplink channel is also used by the unlicensed users. However, it is done in a way that no harm is done to the licensed users' transmission from sharing the same channel with the unlicensed users. However, licensed users' transmission causes interference on the unlicensed network. Poisson point process is used here to model the location of the nodes and the effect of interference on the network. We study how different factors such as number of retransmissions, SIR threshold and outage can effect the throughput and energy efficiency of the network. Throughput and energy efficiency are also both studied in constrained optimization problems where the constraints are the SIR threshold and number of retransmission attempts. We also show why it is important to use limited transmissions and what are the benefits.