Browsing by Subject "IEEE 802.16m"
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Item Open Access A Performance comparision of polar codes with convolutional turbo codes(2009) Özgür, ÜstünPolar codes introduced recently by Arıkan are the first low-complexity codes achieving symmetric capacity for arbitrary binary-input discrete memoryless channels (B-DMCs). Although being theoretically significant, their practical significance is an issue that has not yet been fully explored. Previous studies have compared polar codes with Reed-Muller codes, where it was found that polar codes can outperform them. In this thesis, to investigate how polar codes perform against state-of-the-art forward error correction (FEC) codes used in practice, we implement a IEEE 802.16 based link-level Worldwide Interoperability for Microwave Access (WiMAX) simulator which incorporates several WiMAX FEC options, and polar codes. IEEE 802.16 standards family define standards for current and next generation broadband wireless access, which will make high data rate multimedia applications in mobile environments a reality. Next generation broadband access standard, pursued by the IEEE 802.16 Task Group m is a work in progress, and requires even more sophisticated error correction schemes so that higher throughput, better QOS, higher mobilities, wider ranges and lower latencies are supported. We perform performance comparison simulations with the convolutional turbo codes (CTC) configurations defined in IEEE 802.16e to see how much of a performance gap exists between polar codes and CTCs. The main findings of the thesis are that, although the polar codes achieve capacity for specific conditions, as expected, for the code lengths and channel conditions we have simulated, the performance of them cannot compete with that of the CTCs with equivalent rates and lengths. It remains a task to see whether polar codes can achieve similar performances with CTCs when used as component codes in other configurations and aid in the advancement of new communication technologies.Item Open Access A system level simulation study of WiMAX(2010) Başçiftçi, Yüksel OzanIn this thesis, we implement a WiMAX system level simulator compliant with the evaluation methodology document published by the IEEE 802.16m Task Group. We study the PHY abstraction of polar codes and integrate polar codes into the simulator. We compare the system level performances of polar code and convolutional turbo code (CTC) and observe that CTC outperforms polar code. On the simulator, we study the downlink (DL) performance of WiMAX under various configurations such as scheduling methods, subchannelization methods, and frequency reuse models. We study there types of scheduling methods, namely round robin (RR) scheduling, proportional fair (PF) scheduling, and maximum sum rate (MSR) scheduling. We observe that MSR scheduling has the best throughput performance but does not support the users far from the base station. We study three frequency reuse models, namely 1×3×1, 1×3×3, and 3×3×1. We observe that 1 ×3×1 reuse model has the best throughput performance and maximum spectral efficiency is obtained in 1 × 3 × 3 reuse model. We study two subchannelization methods, namely PUSC and band AMC. We observe that in low mobility cases, band AMC outperforms PUSC and in high mobility cases, PUSC is better than band AMC.