Ákos Milánkovich

Optimized packet size for energy efficient delay-tolerant sensor networks

In wireless smart metering optimization for energy efficiency is indispensable, because in case of systems without external power supply, battery life is a key factor regarding the usability of the whole system. Sensor networks are less sensitive for delay, this is why aggregation of packets is possible. The aim of this paper is to determine analytically the amount of meter records to aggregate in one packet, regarding the SNR which characterizes the quality of the channel, so that the energy usage is optimal. The introduced formulas, help determining scheduling parameters in wireless smart metering systems. The calculations are presented on a real world scenario and system using GFSK modulation.

Radio Propagation Modeling on 433 MHz

In wireless network design and positioning it is essential to use radio propagation models for the applied frequency and environment. There are many propagation models available for both indoor and outdoor environments; however, they are not applicable for 433 MHz ISM frequency, which is perfectly suitable for smart metering and sensor networking applications.

Passive extended double-sided two-way ranging algorithm for UWB positioning

Wireless sensor networks gain ground rapidly due to their potentially low cost. These networks, including variants with UWB (ultra-wideband) physical layer, can be utilized extremely well for positioning because of the technological capabilities. However, the accuracy of localization based on the measurement of time depends on the usage of timestamps provided by certain elements of the network. This article proposes a method to use time of arrival (ToA) also known as time of flight (ToF) measurements in an UWB technology-based passive asynchronous localization strategy (which provides low-power and quick positioning) in combination with extended two-way ranging to improve accuracy named by the authors as PE-ranging. The proposed method makes the positioning system more resistant to clock drift, while requires fewer messages due to the passive nature of the solution. First, the traditional variants of two-way ranging (TWR) are introduced, contributing the foundation of the proposed strategy, then the so-called PE-ranging is explained, which is a localization strategy based on indirect distance-measurement.

Research on Payload Aggregation of Packets in WSNs

Creating wireless sensor networks requires a different approach than traditional communication networks because energy efficiency plays a key role in sensor networks, which consist of devices without external power. The amount of energy used determines the lifetime of these devices. In most cases data packets are less sensitive to delay, thus can be aggregated, making it possible to gather more useful information reducing the energy required to transmit information. This article discusses the energy efficiency of different Forward Error Correction algorithms and presents a method to calculate the optimal amount of aggregation of the data packets in terms of power consumption, while taking into account the Bit Error Rate characteristics of the wireless channel. The contribution of this paper is a general method to improve the energy efficiency of wireless sensor networks by using the optimal amount of aggregation in case of different FEC codes and channel characteristics. The presented results can be applied to any packet-based wireless protocol.