Catálogo de publicaciones - libros

In wireless sensor networks, energy efficiency has been a key factor. So far, many energy-efficient routing protocols have been proposed and much attention has been paid to cluster-based routing protocols due to their advantages. However, some cluster-based sensor network routing protocols need location information of the sensor nodes in the network to construct clusters efficiently. Owing to the cost, it is not feasible to know the locations of all sensor nodes in the sensor network. In this paper, we propose a sophisticated base station centralized simple clustering protocol (SBCSP). The proposed protocol utilizes the remaining energy of each sensor node, standard deviation of their energy consumed and the number of cluster heads changed depending on the number of sensor nodes alive in the sensor network. Throughout the performance experiments, we show that SBCSP has better performance than low-energy adaptive clustering hierarchy (LEACH).

We study tree-based routing protocols for wireless sensor networks. The existing tree-based algorithm has a few shortcomings; (1) it may take a long path since sensor node must transmit packets via either its parent or its children nodes and (2) it is vulnerable to a link failure since the tree has to be reconstructed in case of a single link failure. We propose Plus-Tree, a routing protocol, which overcomes the shortcomings and improves the performance of the existing protocol. A node in Plus-Tree may have neighbor links other than tree links that can be used for alternative path. Simulation results show that Plus-Tree performs better than the existing tree-based protocol with respect to hop counts.

Wireless communication links are time-varying in nature, causing degradation of network’s performance; this however, could be alleviated by allowing cross layer interaction in the protocol stack. Hence, optimization problems formulated in this paper considered parameters from the physical, MAC, and network layers where an optimal transmission power vector that minimizes the overall transmission power of the network, satisfying the SINR, required data rate, and maximum transmission power constraints was formulated to exist. Distributed algorithms for the joint scheduling, power control and routing were also derived and an energy-aware routing algorithm which maximizes network lifetime was proposed. The energy consumed by each node in the routing path and delays associated on each transmission were considered as link cost such that a route with minimum link cost is utilized. Basically, the routing algorithm searched an energy-efficient route, satisfying the energy constraint of each node in a routing path at a tolerable delay.

Quantitative analysis and prediction of radio attenuation is required in order to improve reliability of satellite-earth communication links and for economically efficient design. For this reason, many countries have made efforts to develop their own rain attenuation prediction models which are fit for their rain environment. In this study the slant path length adjustment factor and rain height proposed in Korea and Japan was applied to ITU-R model (P.618-5, P.618-8), which is most widely used in the world. Their results were compared to measured data of rain attenuation and their effectiveness and validity were examined through evaluating the Pearson correlation coefficient.