Various modulation schemes may be implemented for wireless communication. For example, a first modulation scheme may include an Orthogonal-Frequency-Division-Multiplexing (OFDM) modulation scheme. A second modulation scheme may include a single-carrier (SC) modulation scheme, e.g., a SC with Frequency-Domain Equalization (SC-FDE) modulation scheme. Both communication schemes have utilities and deficiencies relative to each other.
Some wireless communication systems may implement two modulation schemes, e.g., both the OFDM and SC-FDE modulation schemes. For example, the IEEE 802.11 task group ad (TGAD) specification may utilize both the OFDM and SC-FDE modulation schemes. The implementation of several Physical (PHY) layer protocols to support the two different modulation schemes may complicate end product design.
The OFDM and SC-FDE modulation schemes utilize different sampling rates. Accordingly, the processing of OFDM and SC-FDE signals may require using two separate Analog to Digital Converters (ADCs), having two different sampling rates. However, the use of two ADCs may increase complexity. It may be advantageous to implement one ADC to apply the same sample rate for processing both SC-FDE and OFDM signals.
A receiver implementing the common ADC may utilize a sampling rate of the OFDM modulation scheme. For further processing of a SC-FDE signal sampled at the OFDM sampling rate, the receiver may utilize a resampling scheme in time-domain after the ADC, to convert between the OFDM and the SC-FDE sampling rates. For example, the receiver may insert zeroes between the samples to double the number of samples, may approximate the SC-FDE sample values in the positions of the inserted zeroes, and may sample the approximated samples at a reduced sampling rate, e.g., sampling every third sample. This approximation, which may a finite-length time-domain interpolation filter leads to performance degradation, e.g., in comparison with a theoretically ideal resampling scheme.