CAT-M1 Modulation

Quoted from SC-FDMA Single Carrier FDMA in LTE by IXIA

 

 

 

 

1. OFDM

Each data symbol is carried by the individual subcarriers.

 

 

IFFT: 주파수성분을 가지고 시간도메인 파형

FFT: 시간도메인 파형에서 주파수성분을 추출

 

 

 

 

2. SC-FDMA

 

 

 

 

3. Sub Carrier Mapping

Localized와 interleaved 매핑방식 중에서 LTE는 localized mapping 방식을 사용한다.

 

 

 

 

 

4. Why is it called SC-FDMA

DFT-precoded OFDM = DFT-spread OFDM → SC-FDMA

SC-FDMA(?)  → The group of subcarriers that carry each data symbol can be viewed as one frequency band carrying data sequentially in a standard FDMA.

It can be mathematically shown that the SC-FDMA baseband time domain samples after IDFT or IFFT is the original data symbol set repeated in time domain over the symbol period.