An 802.16 model for NS2 simulator with an integrated QoS architecture

The IEEE 802.16 technology is emerging as a promising solution for BWA due to its ability to support multimedia services and to operate in multiple physical environments. Also, with data rates in excess of 120 Mbps, it provides a cost-effective alternative to wireline broadband access systems. Unfortunately no open-source simulation environment supporting this technology has been proposed so far. Therefore this work is meant to be a contribution to build an 802.16 simulation model for NS2, the most popular network simulator. In this paper, we present the details of design and implementation of the proposed simulation model. Our model includes a novel QoS architecture, and addresses 802.16 fixed BWA systems that use Orthogonal Frequency Division Multiplexing (OFDM) modulation and operate in TDD mode. The QoS architecture we propose consists of a call admission control (CAC) policy and a hierarchical scheduling algorithm that flexibly adjusts uplink and downlink bandwidth to serve unbalanced traffic. Both scheduling and CAC algorithms are based on an adaptive modulation and coding (AMC) scheme.