Estimation and compensation of frequency offset in DAC/ADC clocks in OFDM systems

A frequency offset between the clocks in the digital-to-analog-converters (DAC's) in the transmitter and the analog-to-digital-converters (ADC's) in the receiver would severely impact the performance of an OFDM communication system. The effect of the frequency offset can be approximated as...

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Bibliographic Details
Main Authors: Shafiee, H., Nourani, B., Khoshgard, M.
Format: Conference Proceeding
Language:English
Subjects:
Analog-digital conversion, digital-analog conversion, pcm coding
Applied sciences
Baseband
Clocks
Conferences
Equalizers
Exact sciences and technology
Frequency estimation
Information, signal and communications theory
Multiplexing
OFDM modulation
Radiocommunications
Sampling methods
Signal and communications theory
System testing
Systems, networks and services of telecommunications
Telecommunications
Telecommunications and information theory
Transmitters
Transmitters. Receivers
Wireless communication
Wireless LAN
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Summary:A frequency offset between the clocks in the digital-to-analog-converters (DAC's) in the transmitter and the analog-to-digital-converters (ADC's) in the receiver would severely impact the performance of an OFDM communication system. The effect of the frequency offset can be approximated as a phase rotation for each sample of an OFDM symbol, where the amount of the rotation is proportional to the sub-channel index. In this paper, an algorithm for the compensation of such a frequency offset is proposed which uses the pilot tones present in each OFDM symbol. The required phase corrections for samples in all sub-carriers are determined and applied. The proposed algorithm is tested on an OFDM communication system whose parameters are selected based on IEEE 802.11a standard for wireless local area networks (WLAN). Simulation results show that the algorithm works quite effectively even with large amounts of frequency offsets.
DOI:10.1109/ICC.2004.1312948