LoRaWAN is a flagship Low-Power Wide Area Network (LPWAN) technology that has highly attracted much attention from the community in recent years. Many LoRaWAN end-devices, such as sensors or actuators, are expected not to be powered by the electricity grid; therefore, it is crucial to investigate the energy consumption of LoRaWAN. However, published works have only focused on this topic to a limited extent. In this paper, we present analytical models that allow the characterization of LoRaWAN end-device current consumption, lifetime and energy cost of data delivery. The models, which have been derived based on measurements on a currently prevalent LoRaWAN hardware platform, allow us to quantify the impact of relevant physical and Medium Access Control (MAC) layer LoRaWAN parameters and mechanisms, as well as Bit Error Rate (BER) and collisions, on energy performance. Among others, evaluation results show that an appropriately configured LoRaWAN end-device platform powered by a battery of 2400 mAh can achieve a 1-year lifetime while sending one message every 5 min, and an asymptotic theoretical lifetime of 6 years for infrequent communication.

Sigfox has become one of the main Low-Power Wide Area Network (LPWAN) technologies, as it has attracted the attention of the industry, academy and standards development organizations in recent years. Sigfox devices, such as sensors or actuators, are expected to run on limited energy sources; therefore, it is crucial to investigate the energy consumption of Sigfox. However, the literature has only focused on this topic to a very limited extent. This paper presents an analytical model that characterizes device current consumption, device lifetime and energy cost of data delivery with Sigfox. In order to capture a realistic behavior, the model has been derived from measurements carried out on a real Sigfox hardware module. The model allows quantifying the impact of relevant Sigfox parameters and mechanisms, as well as frame losses, on Sigfox device energy performance. Among others, evaluation results show that the considered Sigfox device, powered by a 2400 mAh battery, can achieve a theoretical lifetime of 1.5 or 2.5 years while sending one message every 10 min at 100 bit/s or 600 bit/s, respectively, and an asymptotic lifetime of 14.6 years as the message transmission rate decreases.

Bluetooth Low Energy (BLE) has gained very high momentum, as witnessed by its widespread presence in smartphones, wearables and other consumer electronics devices. This fact can be leveraged to carry out opportunistic sensor data collection (OSDC) in scenarios where a sensor node cannot communicate with infrastructure nodes. In such cases, a mobile entity (e.g., a pedestrian or a vehicle) equipped with a BLE-enabled device can collect the data obtained by the sensor node when both are within direct communication range. In this paper, we characterize, both analytically and experimentally, the performance and trade-offs of BLE as a technology for OSDC, for the two main identified approaches, and considering the impact of its most crucial configuration parameters. Results show that a BLE sensor node running on a coin cell battery can achieve a lifetime beyond one year while transferring around 10 Mbit/day, in realistic OSDC scenarios.

Abstract-Frequency channels are a scarce resource in the ISM bands used by IEEE 802.11 WLANs. Current radio resource management is often limited to a small number of nonoverlapping channels, which leaves only three possible channels in the 2.4GHz band used in IEEE 802.11b/g networks. In this paper we study and quantify the effect of adjacent channel interference, which is caused by transmissions in partially overlapping channels. We propose a model that is able to determine under what circumstances the use of adjacent channels is justified. The model can also be used to assist different radio resource management mechanisms (e.g. transmitted power assignments)

Abstract

The growth of IEEE 802.11 wireless local area networks (WLANs) (Wi-Fi) brings new possibilities of getting connected in public spaces, known as Hot Spots. Current client-access point associations are an interesting research topic because in these scenarios, users tend to be 'gregarious' and essentially static. Under IEEE 802.11 standards, association and roaming decisions are made by client devices and most implementations are based on signal strength measurements; i.e. a client station selects the access point (AP) that provides the strongest signal, which leads to an uneven distribution of clients and load between neighbouring APs. As it can be observed in practical scenarios, the default AP-client association scheme followed in IEEE WLANs, produces unfair situations. This work provides means to effectively alleviate this performance issue and also gives details for a feasible implementation. In this paper we analyse how new IEEE 802.11 standards will allow new radio measurements to provide more efficient association decisions. We propose a new load metric that will produce client-driven associations that ensure greater fairness and throughput.

As the number of WLAN users grows, the need to perform efficient radio resource management strategies becomes essential due to the fact that most popular technologies, those based on IEEE 802.11 standards, use unlicensed frequency bands. A good channel assignment improves the network performance, producing benefits that are perceived by the users and also by the network administrators. In this paper, we present a new frequency management scheme for IEEE 802.11 WLANs in the 2.4 GHz ISM band that minimizes interference to increase the throughput available to client stations by adapting a weighted DSATUR algorithm for graph coloring. The algorithm takes both co‐channel and adjacent channel interference into account, and makes use of all available channels instead of the traditional non‐overlapping three. In this way, collisions as well as transmission errors are minimized, thus improving the network capacity and the user experience. Different architectures are discussed for the implementation of our approach, including the possibility to incorporate client stations into the management system. Copyright © 2008 John Wiley & Sons, Ltd.

Abstract