(m,k)-firm pattern spinning to improve the GTS allocation of periodic messages in IEEE 802.15.4 networks

Abstract

The IEEE 802.15.4 standard provides a flexible communication support for low-rate wireless personal area networks) applications. When active, the beacon-enabled mode provides a real-time communication to the supported application by adopting a guaranteed time slot (GTS) mechanism. However, this mechanism permits only up to seven real-time communicating devices. One way to deal with this limitation is to share the communication opportunities among the periodic tasks, by skipping some of the task activations in a controlled way. One of the widely accepted periodic task models that allows skips in periodic activations is the (m,k)-firm model. Motivated by this problem, this paper proposes the use of a dynamic GTS scheduling approach based on the (m,k)-firm task model, to deal with the GTS starvation problem. The proposed scheduling approach is based on pre-defined spins of the originally defined (m,k)-firm pattern. The use of an exact schedulability analysis test ensures that for each admitted message stream, at least m messages will be transmitted within each window of k consecutive deadlines. The schedulability analysis may be executed in polynomial time and therefore can be used as an online admission test for GTS requests. The effectiveness of the approach has been assessed both by a set of simulations and an experimental evaluation.

Review: Algoritmos de planificación para la transmisión de datos en tiempo real con IEEE 802.15.4

“…1) Asignación dinámica de time-slot para GTS: en este apartado se inicia con el estudio de [41,42] en el cual, el número de time-slot GTS que se define por defecto en el estándar IEEE 802.15.4 no es suficiente, debido a que se quedan muchos requerimientos sin atender, sobre todo cuando se tiene una tasa de paquetes alta y, por ende, los retardos en la entrega de los mismos pueden ser cada vez mayores.…”

“…Por lo anterior, [41,42] proponen un modelo dinámico para el manejo de tareas en tiempo real basado en la forma (m,k)-firm constraints, donde m son los mensajes por transmitir y k los plazos consecutivos en los cuales se deben transmitir. El modelo propone un sistema polinomial en el manejo de los time-slot, de manera que se puedan asignar los GTS eficientemente.…”

Quality of service provision assessment for DDBP approach in IEEE 802.15.4 networks

“…This scarce resource is rapidly extinguished, when considering networks with a large number of nodes. To improve the GTS allocation mechanism, we proposed in [6] a new GTS allocation model for WSN operating in beacon-enable mode, which was extended in [7]. One of the problems of these type of centralized approaches is that it considers a controlled communication model.…”

Skip game: an autonomic approach for QoS and energy management in IEEE 802.15.4 WSN

“…Besides the energy consumption, WSN applications may have other concerns, such as supporting real-time traffic [1], [2], increasing the spatial diversity of the network coverage [3] and maximizing the number of messages that arrive at the base station [4]. Moreover, redundant WSN deployment adds new challenges in the design and management of sensor networks, being necessary the adoption of some autonomic communication approach to keep the network operational for longer periods without human intervention.…”