Design Considerations For The Compensation Of Phase Noise In OFDM Systems

OFDM has been used in many wireless communication systems, due to its ability to repress multipath propagation, frequency selective fading and high spectral efficiency. However, the orthogonality between subcarriers is crucial to OFDM, so it is sensitive to the phase noise of local oscillator. Phase noise on the OFDM signal has two effects: Common Phase Error (CPE) and Inter-Carrier Interference (ICI). In summary the algorithm predecessors to draw, due to the limit of pilots in OFDM system, the method using zero-forcing (ZF) and minimum mean square error (MMSE) to realize CPE estimates is not right CPE accurate estimate, however the spectrum efficiency will be reduced if we increase the number of pilot. Therefore, a decision feedback algorithm based phase noise compensation algorithm is used in this thesis to obtain the estimation of CPE using pilot samples in received signals, and use this estimation to correct the data sub-carrier; re-use of corrected data sub-carrier to estimate CPE further, finally, estimate the data sub-carrier. Based on IEEE802.11a system, we have completed the simulation of elimination of phase noise at the receiver, and the simulation is proven to achieve the desired results.This article concludes with a discussion of hardware design and implementation for the decision-feedback phase noise suppression algorithm. We have given the overall structure of suppression module and the details of each sub-module. And completed the floating-point to fixed-point conversion of all the sub-modules, after repeated simulation, the performance of fixed-point achieved the desired results.