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Quantization Effects in OFDM Systems
The advantage of using orthogonal frequency division
multiplexing (OFDM) over the single-carrier modulation is its
ability to mitigate interference and fading without complex
equalization filters in the receiver. OFDM systems
have a high peak-to-average ratio (PAPR) which results in a high
requirement for the resolution of AD converters. High-resolution AD
converters are therefore widely used in OFDM receivers. However, the
power consumption is proportional to the resolution of the AD
converters. In this paper we investigate the quantization effects in
OFDM systems. Quantization is a nonlinear function which happens in
the time domain, so the quantization effect in the frequency domain
(important for OFDM) is not simple. Here, we derive a model for the
quantization effect in the frequency domain. Further, we investigate
whether it is possible to apply low-resolution AD converters in
reliable communications based on OFDM. Simulations with an AWGN
channel reveal that the proposed model predicts the quantization
noise in the frequency domain very well. Difference in
between simulation outcomes and our model is
less than 0.6\%. Also, simulations show that 5-bits AD resolution is
required for OFDM communication over an AWGN channel
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