Evaluation of wimax admission control algorithms in mobile voip scenarios with batch arrivals and nbldpc fec

This paper presents results of assessing quality of VoIP conversations in WiMAX networks using the nbLDPC (non-binary Low- Density Parity-Check) FEC in mobility scenarios that are based on the real world terrain charactristics around simulated BS. System under test (SUT) is instrumented with three Call Admission Control (CAC) mechanisms (namely EMAC, ARAC and nsc-ARAC). These algorithms are evaluated against controlling the VBR traffic that comes with burst arrivals. The first algorithm relies on calculating simple exponential weighted moving average (EWMA) of the overall resource consumption whereas the other two ARAC algorithms perform calculations discerning between the new, the ongoing and the finishing connections thus providing more accurate resource estimations (but the ARAC tracks the history of requests as well). In order to evaluate their performance authors rely on a cell-level based simulation environment that relies on the cooperative use of well known simulators - ns2 and Matlab. Previous work in the field is enhanced by improving the fidelity of proposed IEEE 802.16 simulator. Authors demonstrate the influence of increasing number of arrivals per one batch as well as testing the "zero hour" scenario (system saturation). In order to include nbLDPC codes in SUT’s mobile channels, a method called Link-To-System interface (L2S) has been implemented.