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In this work, we resort to computer simulations to compare the coverage of long range (LoRa) and narrowband (NB)-IoT in two different realistic scenarios of southern Brazil, encompassing an overall area of 8182.6 km2. The first scenario is predominantly rural with a few base stations (BSs) while the other scenario corresponds to a mostly urban area with high density of BSs. Our analysis, which adopts the actual position and parameters of the BSs of a given operator, also takes into account the digital elevation model (DEM) of the environments in order to calculate the path loss, following a realistic propagation model from 3GPP. Our results indicate that for a mainly rural environment, when operating at a similar sub-GHz frequency band, NB-IoT outperforms LoRa due to the directivity associate with directional antennas which provide a better coverage for devices which are far from BS but near the main beam. However, LoRa presents a better coverage, regardless of the site deployment, when the NB-IoT is considered to operate in the 1900-MHz band. [ABSTRACT FROM AUTHOR]

IEEE 802.15.4 has emerged as a popular standard for short range wireless sensor networks used in industrial, military, health, and environmental sectors. The limited lifetime of such networks is one of the critical design challenges. This paper examines the how relaying through intermediate sensor nodes can enhance the lifetime of an 802.15.4 network. In particular, novel energy consumption models for both AF and DF relays have been developed. Different relay gain scaling mechanisms and forwarding strategies under each of the relay categories were also considered and their energy efficiencies were compared. For every relaying protocol, it was found that there exists an optimum location where energy saving is maximum and this location is not necessarily different for different modes. In summary, it has been observed that the optimum location for AF relays is the equidistant point from source and destination. In contrast, the optimal location for DF relays is closer to source. The effect of different PHY level (outage probability, path loss) and MAC level parameters (frame length) on the energy efficiency are also studied. [ABSTRACT FROM AUTHOR]

In this paper we analyze the energy efficiency of single-hop, multi-hop, cooperative selective decode-and-forward, cooperative incremental decode-and-forward, and even the combination of cooperative and non-cooperative schemes, in wireless sensor networks composed of several nodes. We assume that, as the sensor nodes can experience either non line-of-sight or some line-of-sight conditions, the Nakagami-m fading distribution is used to model the wireless environment. The energy efficiency analysis is constrained by a target outage probability and an end-to-end throughput. Our results show that in most scenarios cooperative incremental schemes are more energy efficient than the other methods. [ABSTRACT FROM AUTHOR]

In this paper we propose a cooperative scheme in which fixed relays operate with a higher spectral efficiency than the source. The relay transmits L times faster than the source with L times the spectral efficiency, reducing the loss inherent to the orthogonal cooperation. We assume a large scale path loss model which is capable of handling with heterogeneous conditions between the nodes of the network: the source, the relay and the base-station antennas can be at different heights. Our results show that the proposed scheme consumes less energy while achieving up to 3 dB of gain, in terms of throughput, when compared to the baseline cooperative scheme. In addition, a coverage area analysis shows that the proposed scheme increases considerably the cell area when compared to the non-cooperative transmission and to the baseline cooperative scheme. Finally, we show that the proposed scheme, with a single relay, outperforms in the high signal to noise ratio region the regular cooperative scheme using multiple relays. [ABSTRACT FROM AUTHOR]

In this paper we investigate the combination of rate and power allocation techniques in an orthogonal cooperative scheme using infra-structured (fixed) relays, under the incremental decode-and-forward protocol. We consider realistic large scale and small scale path loss models, taking into account the antennas heights and the presence or not of line-of-sight. Results demonstrate that the throughput performance can be significantly increased in the low signal-to-noise ratio (SNR) region due to rate allocation (RA), and in the high SNR region due to power allocation (PA). In addition, we present an energy efficiency analysis which shows that RA is much more efficient than PA over the whole SNR range. [ABSTRACT FROM AUTHOR]