Performance Analysis of WiMAX
Date Issued
2008
Date
2008
Author(s)
Chiu, Hsu-Feng
Abstract
IEEE 802.16 wireless metropolitan area networks have recently become an extremely popular network technique. However, within the new protocol, performance is still not broadly discussed. This research aims at the investigating of the performance and potential issues. In our study, the NIST modules upon NS2 are utilized to acquire a fair performance analysis. We investigate the ability of WiMAX with immobile users under different parameters of PHY and MAC. First, we would like to figure out how modulation affects on throughput. As modulation is becoming better, throughput is getting higher. With the best modulation 64-QAM-cc-3/4, throughput is up to 52Mbps. Second, we measure throughput with different traffic loadings. In increasing traffic loading we will get higher throughput. However, a high traffic loading will cause the bandwidth request overflowed. Thus we will get abnormal throughput. Third, we allocate different numbers of SSs in our scenario to observe the time delay. The result shows that more SSs will cause larger delay. However, packet loss has a more significant effect on influencing decrease of delay. Finally, we test the performance of different applications including Voice over IP (VoIP), video stream and data. Obviously, VoIP traffic type has the least delay. When testing the handoff function, we find that three problems exist in DSDV (Destination-Sequenced Distance-Vector Routing). The first one is concerned with the domain restriction. BSs have to be in different domains, or neighbor BSs can’t be found. The secondary issue is the path selection. Packets in MS can not find the right routing path, which will cause the failure of data transmission. In addition, using DSDV takes more than ten seconds to reconnect after handoff accomplishing. To overcome the above problems, we utilize the mobile module of NIST to support the handoff function in IEEE 802.16e. The module includes MIHF (Media Independent Handover Function) agent for performing packet delivering and ND (Neighbor Discovery) agent for neighbor discovering. Our result reveals that the handover latency is less than 50 ms even when velocity is up to 70 km/hr. This research discovers the effects on performance with different modulation, traffic loading, numbers of SSs, and applications. We also find that using DSDV in processing handoff has potential problems and could be successfully carried out by MIHF and ND agents. In summary, our experiments indicate that WiMAX indeed has superior performance on throughput and mobility. Our results could be provided as references for designing and certifying real products.
Subjects
Performance
WiMax
802.16e
NS2
handover
Type
thesis
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