Increasing the Throughput of an Unlicensed Wireless Network through Retransmissions

Abstract

This paper analyzes the throughput of an unlicensed wireless network where messages decoded in outage may be retransmitted. We assume that some wireless devices such as sensors are the unlicensed users, which communicate in the licensed uplink channel. In this case, the licensed users that interfere with the unlicensed transmissions devices are mobile devices whose spatial distribution are assumed to follow a Poisson point process with respect to a reference unlicensed link. We investigate how the number of allowed retransmissions and the spectrum efficiency jointly affect the throughput in [bits/s/Hz] of a reference unlicensed link for different licensed network densities, constrained by a given required error rate. The optimal throughput is derived for this case as a function of the network density. We also prove that the optimal constrained throughput can always reach the unconstrained optimal value. Our numerical results corroborate those of the analytical findings, also illustrating how the number of allowed retransmissions that leads to the optimal throughput changes with the error rate requirements.

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

“…In our previous work, we can see that in [12, Lemma 2], we use an approximation of (7) (which is also shown in this paper as (12)) presented in this analysis in order to calculate the average number of retransmissions in the throughput optimization problem in [12]. In this section we aim to prove that this previously used approximation is in fact a tight and good approximation and the error in calculations is low when using the approximated expression.…”

“…Taking into account the aforementioned system model assumptions, it is possible to conclude that if the licensed and unlicensed nodes are implemented in explicit positions, it makes it possible to eliminate the interferences in cases (i) and (ii). Even if it is assumed that the nodes are implemented in random locations, the probability of having the base station or aggregator in the same line segment as the unlicensed nodes signal is close to zero [10], [12], [15]. As follows, the only source of interference in this model is then (i).…”

“…Hence, a Poisson point process Φ is used to model the interfering nodes distributed over an infinite two-dimensional plane where λ ą 0 (average number of nodes per m 2 ) denotes the spatial density. This model is also elaborated in details in [12], [30].…”

“…Since these works are limited to smart grids applications, we later on expanded these works in [12], by following the work done in [13], [14], to make the model more generalized and compatible with other wireless networks. In this paper, we follow the same model as in [10], [12], [15] to prove that the approximation used there for the average number of retransmission attempt is in fact a tight approximation. We show why it is worth to use limited number of retransmission, and optimize the throughput as a function of the SIR threshold and number of retransmissions.…”

Energy Internet via Packetized Management: Enabling Technologies and Deployment Challenges

“…One line of research is the development of an energy-weather forecast by the Finnish Meteorological Institute as a tool to predict the electricity production from solar and wind with their most recent meteorological model. Other research line is the analysis of machine-type communications and IoT networks in the context of energy system as in [54]- [59]. In more recent work [60], Tomé et al gave the first step to combine them by focusing on how weather forecast and statistical analysis of electricity demand could be the basis of energy storage management in households and micro-grids.…”