Dynamic Path Loss Research Articles

Multiconstraint-Aware Routing Mechanism for Wireless Body Sensor Networks

The merger of wireless sensor technologies, pervasive computing, and biomedical engineering has resulted in the emergence of wireless body sensor network (WBSN). WBSNs assist human beings in various monitoring applications such as health-care, entertainment, rehabilitation systems, and sports. Life-critical health-care applications of WBSNs consider both reliability and delay as major Quality of Service (QoS) parameters. In addition to the common limitations and challenges of wireless sensor networks (WSNs), WBSNs pose distinct constraints due to the behavior and chemistry of the human body. The biomedical sensor nodes (BMSNs) adopt multihop communication while reporting the heterogeneous natured physiological parameters to the nearby base station also called local coordinator. Routing in WBSNs becomes a challenging job due to the necessary QoS considerations, overheated in-body BMSNs, and high and dynamic path loss. To the best of our knowledge, none of the existing routing protocols integrate the aforementioned issues in their designs. In this research work, a multiconstraint-aware routing mechanism (modular-based) is proposed which considers the QoS parameters, dynamic and high path loss, and the overheated nodes issue. Two types of network frameworks, with and without relay/forwarder nodes, are being used. The data packets containing physiological parameters of the human body are categorized into delay-constrained, reliability-constrained, critical (both delay- and reliability-constrained), and nonconstrained data packets. NS-2 is being used to carry out the simulations of the proposed mechanism. The simulation results reveal that the proposed mechanism has improved the QoS-aware routing for WBSNs by adopting the proposed multiconstraint-aware strategy.

Received Signal Strength-Based Robust Cooperative Localization With Dynamic Path Loss Model

Robust received signal strength (RSS)-based cooperative wireless localization using a linear least squares (LLS) method is proposed. We first extend the LLS methods to the cooperative case. To make the proposed algorithm robust, dynamic path loss models are utilized to describe the changing environments; the path loss constants are updated based on the estimated positions of the client nodes. Furthermore, anchor nodes (reference nodes) calibration is considered to deal with the anchor node position errors. The simulation results are given for the proposed methods. Compared with the RSS-based non-cooperative LLS type methods, robust and better performance are obtained.

Interference estimation in wireless mobile random waypoint networks

It is well known that the stochastic nature of the interference deeply impacts on the performance of emerging and future wireless communication systems. In this work we consider an ad hoc network where the nodes move according to the Random Waypoint mobility model. Assuming a time-varying wireless channel due to slow and fast fading and, considering the dynamic path loss due to the mobility of the nodes, we start by characterizing the interference distribution caused to a receiver by the moving interferers located in a ring. Based on the interference distribution, we evaluate two different methodologies to estimate the interference in real-time. The accuracy of the results achieved with the proposed methodologies in several simulations show that they may used as an effective tool of interference estimation in future wireless communication systems, being the main contribution of this work.

Analysis of dynamic path loss based on the RSSI model for rupture location analysis in underground wireless sensor networks and its implications for Earthquake Early Warning System (EEWS)

Sensors deployed in underground tunnels found that radio frequency signals suffer significant signal strength attenuation which can result in considerable variation of link quality on the receiving end. This study analyzes the received signal strength index (RSSI) based on the development of a theoretical wireless sensor model for data collection by enabling sensors to determine the location from which each data packet is obtained. To improve positioning accuracy, the complex radio wave propagation environment requires the use of a voronoi cell to minimize signal attenuation. A relatively simple calculation is used to predict the intensity and perception range of the received wireless signals to measure the extent of signal reduction in the attenuating rock medium. Simulation results show that RSSI-based localization and wireless network lifetime and throughput measurements are more accurate when the node concept is applied to the self-locating rupture zones than the maximum likelihood estimation method. The proposed minimum energy relay routing technique based on beacon node chain deployment is found to help correct localization errors resulting from interference caused by the underground tunnel environment. The extent of localization and power of the sensor nodes are determined based on the beacon node chain deployment of tunnel wireless sensor networks. The algorithm accounts for the distance and the corresponding RSSI between adjacent beacon nodes to calculate the actual path loss parameter in the tunnel. The proposed model can serve as the theoretical basis for locating ruptures in underground wireless sensor network nodes, thus maximizing the monitoring range of large scale tectonic environments while minimizing equipment cost. We recommend that this model can be field tested through a series of experiments by researchers and engineers working in seismology, telecommunication, and information technology.

Data-Centric Routing for Intra Wireless Body Sensor Networks.

A significant proportion of the worldwide population is of the elderly people living with chronic diseases that result in high health-care cost. To provide continuous health monitoring with minimal health-care cost, Wireless Body Sensor Networks (WBSNs) has been recently emerged as a promising technology. Depending on nature of sensory data, WBSNs might require a high level of Quality of Service (QoS) both in terms of delay and reliability during data reporting phase. In this paper, we propose a data-centric routing for intra WBSNs that adapts the routing strategy in accordance with the nature of data, temperature rise issue of the implanted bio-medical sensors due to electromagnetic wave absorption, and high and dynamic path loss caused by postural movement of human body and in-body wireless communication. We consider the network models both with and without relay nodes in our simulations. Due to the multi-facet routing strategy, the proposed data-centric routing achieves better performance in terms of delay, reliability, temperature rise, and energy consumption when compared with other state-of-the-art.

Critical Data Routing (CDR) for Intra Wireless Body Sensor Networks

Recently, Wireless Body Sensor Network (WBSN) has been emerged as a promising technology to provide medical and healthcare monitoring. It can significantly reduce the health-care cost by providing continuous health monitoring facility to the elderly people suffering from chronic diseases. The life critical and real time medical application of WBSNs requires the assurance of the demanded Quality of Service (QoS) both in terms delay and reliability. This paper proposes Critical Data Routing (CDR) that categorizes the sensory data packets as critical and non-critical data packets. Along with the heterogeneous natured data, it also addresses the high and dynamic path loss and the temperature rise issues caused by postural movement of the human body and electromagnetic waves absorption respectively. The simulation results show that the proposed CDR scheme achieves its designed objective of forwarding the critical data packets within certain time limits and with highest reliability while reducing the temperature rise of the in-body sensor nodes.

Reliability Aware Routing for Intra-Wireless Body Sensor Networks

With the promise of cost effective, unobtrusive, and unsupervised continuous monitoring, wireless body sensor networks (WBSNs) have attracted a wide range of monitoring applications such as medical and healthcare, sport activity, and rehabilitation systems. Most WBSN's medical and healthcare applications are real-time and life-critical, which require strict guarantee of quality of service (QoS), in terms of latency, and reliability. Reliability in routing plays key role in providing the overall reliability in WBSNs. This paper presents reliability aware routing (RAR) for intra-WBSNs that aims to provide high reliability for reliability constraint data packets. It considers the high and dynamic path loss due to body postural movements and temperature rise of the implanted biomedical sensor nodes. We have used two network models in this paper: RAR without Relays (RAR) and RAR with Relays (RARR). The simulation results reveal that RARR outperforms the other state-of-the-art schemes while RAR has slightly low reliability at low data rates as compared to RARR but significantly higher than other state-of-the-art schemes.

A Wireless Sensor Network Localization Method Based on Dynamic Path Loss Exponent

The path loss exponent shows the effect of space environment on the RF signals in wireless communication model. In most RSSI based location method the path loss exponent is assigned a fixed empirical value which can not reflect the actual environmental impact of the wireless signal, which lead to low position accuracy and considerable positioning error. Aiming at some complex and rapidly changing environment a path loss exponent dynamic acquired algorithm is proposed, which can calculate the actual path loss exponent with the distance and the RSSI value information between adjacent beacon nodes. On basis of the path loss exponent dynamic acquired algorithm a path loss exponent dynamic acquired based localization algorithm is proposed which can estimate the blind node position with the actual path loss exponent, and can improve the adaptability to the environment of the RSSI location algorithm. The simulation shows that the positioning accuracy of proposed method is significantly improved and the effect of proposed method is more precise than the common RSSI method under the same environment.