Design of Cost Efficient FEQ for IEEE802.16a OFDM System
Date Issued
2007
Date
2007
Author(s)
Lin, Chin-Hsien
DOI
zh-TW
Abstract
In this thesis, the design of IEEE 802.16a OFDM-based WiMAX systems is presented. The system design includes the cost efficient FEQ, dc-tone power detection integer CFO estimation, channel interpolation analysis and the CFO tracking loop.
According to strength-reduced complex-value multiplier, the cost efficient FEQ is proposed to decrease the hardware cost. The hardware cost of proposed FEQ is reduced 19% compared with the conventional FEQ. On the other hand, in order to reduce the ROM size in the channel estimation to store the preamble data, the control-MUX method is proposed. In addition, considering the storage
of the channel coefficient and decision error in the LMS adaptation, the single port RAM is selected to decrease the RAM size requirements. Furthermore, combing the two RAM blocks, channel coefficient RAM and decision error RAM, to a single RAM is applied to the cost efficient FEQ design. Consequently, the total size for
the ROM and RAM can be reduced by 70% and 20% respectively.
Besides, the power consumption is also saved by 53% and 18.4% individually.
Considering integer CFO estimation, the dc-tone power detection in the frequency-domain is proposed to achieve the low-computing estimation. Therefore, the approach can save 85% power and 88.6% hardware cost compared with the matched-filter based integer CFO estimation.
The channel interpolation is necessary in WiMAX systems to obtain the channel information on the odd tones since the preamble only provide the even tones information. Although the complicated interpolation method, Raised-Cosine interpolation, can minimize the estimation error, the method results in the higher hardware cost simultaneously. Therefore, in order to acquire the best trade-off between performance and hardware cost, the estimation error of the
Linear and Piecewise-Parabolic channel is analyzed based on the MSE criterion. According to the analysis results, the Linear and Piecewise-Parabolic interpolation satisfy to system requirement. From the hardware cost point of view, the Linear channel interpolation is adopted for the cost efficient FEQ. Finally, the floating and fixed point SER simulations are presented to meet the system requirements.
Subjects
正交多頻多工調變
低功率
頻域等化器
OFDM
802.16a
FEQ
Cost effecient
Type
thesis