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Advanced Transmission Techniques in WiMAX Part 5

Tham khảo tài liệu 'advanced transmission techniques in wimax part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | MicroTCA Compliant WiMAX BS Split Architecture with MIMO Capabilities Support Based On OBSAI RP3-01 Interfaces 91 Figure 3.10 depicts the deviation measured at the input and of the Kalman filter while Figure 3.11 depicts the deviation measured at the output of the Kalman filter One can see that the initial deviation is the jitter level 20nsxFref 3 clock periods plus some temperature randomly added deviation. At the output of the de-jittering structure the level of the jitter is much lower. Time sec Fig. 3.10 DIFF values in clock periods Fig. 3.11 DIFFdj values in clock periods Figure 3.12 and Figure 3.13 depicts the deviation measured at the input and output of the Kalman filter while a frequency deviation of 1 Hz per second was added for 500 successive seconds and subtracted for the next 500 seconds. One can observe that the DIFFdj signal indicates the need of about 1 Hz reduction of the oscillating frequency for the first 500 seconds and then the need of about 1 Hz adding for the next 500 seconds. 92 Advanced Transmission Techniques in WiMAX Time sec Fig. 3.12 DIFF values in clock periods Fig. 3.13 DIFFdj values in clock periods The results presented in this section were obtained using a hardware platform compliant with Figure 3.1. The inputs and the outputs of the algorithm were transferred to the PC using a UART interface. The pictures were obtained using Matlab. 3.4 Conclusions This section presented a digital method of reducing the jitter level of the PPS signal generated by a GPS receiver. Also a controlling algorithm of a VCXO oscillating frequency was described. The results indicated that the frequency correction was applied only when the thermal state of the oscillator was not stable. False corrections due to the PPS jitter were almost completely eliminated. MicroTCA Compliant WiMAX BS Split Architecture with MIMO Capabilities Support Based On OBSAI RP3-01 Interfaces 93 4. WiMAX base station architecture with MIMO capabilities support based on OBSAI .