Algoritmo de escalonamento adaptativo para o tráfego Uplink em redes IEEE 802.16 com gerenciamento dinâmico de Polling

Abstract

The Worldwide Interoperability for Microwave Access (WiMAX) technology, based on the IEEE 802.16 standard, is a solution for broadband wireless access metropolitan networks, developed to support a wide variability of real-time and non-real time applications. Different from the traditional wireless networks, the IEEE 802.16 standard defines, in the medium access layer, mechanisms to support the Quality of Service (QoS) for the applications. Among these mechanisms, we highlight the scheduling and the Connection Admission Control (CAC). However, the IEEE 802.16 does not define the policies that must be used in the implementation of the scheduling and CAC mechanisms. The scheduling mechanism aims at guarantying the efficient utilization of the bandwidth resources, and thus, promotes the effective use of the wireless link. The CAC mechanism aims at restricting the number of existing connections simultaneously in order to avoid that the wireless link is saturated. This thesis shows a new and efficient scheduling algorithm to uplink traffic in the Base Station (BS). The proposed algorithm is developed to be totally dynamic, mainly in networks that use adaptive modulation functions. Using a cross-layer approach, a deadline based scheme was developed, aiming at minimizing the end-to-end delay for the real-time applications. Moreover, the proposed algorithm interacts with the polling mechanism of the BS, and controls the periodicity of unicast polling to real-time and non-real-time applications, in accordance with the QoS requirements of the applications. Moreover, to avoid the wireless link being saturated for an excessive number of connections, a CAC mechanism that interacts with the proposed scheduling algorithm was developed. The CAC mechanism was also developed using a cross-layer approach. Simulations results show the efficiency of the proposed scheduling algorithm and of the CAC mechanism, mainly in environments where an adaptive modulation was used.