Efficient Joint Estimation and Compensation of CFO, Tx/Rx Frequency-Selective I/Q Imbalance, and the MIMO Radio Channel in OFDM Systems

Table 3

Computational complexity of different schemes.

Scheme	Number of real MULs (per Rx antenna)
SCH1	352+8𝐿c𝑁𝑅+𝑁𝑃𝑁𝑅(129+2log2𝑁𝑃)+222𝑁𝐼4+𝑁𝑃𝑁𝑅+𝑁𝑅𝑁𝑇4𝐿h+8𝐿c𝐿^′+2𝑁log2𝑁+4𝑛𝜏+𝑁𝑉log2𝑁𝑉+2𝑁𝑅𝑁𝑉,𝐷1+𝐿c+10𝑁𝑇
SCH2, R	2𝑁𝑃+2𝑁𝑅𝑁𝑃log2𝑁𝑃+8𝐿h𝐿^′𝑁𝑅𝑁𝑇+4𝑁𝑇𝑁𝑅𝑁log2𝑁+4𝑁𝑅𝑁rep𝑁𝑃+13𝑁𝑅𝑁𝐼+160+3𝑁rep𝑁𝑃+𝐿c2+30𝑁𝑃+𝐿c3+𝐿c+𝑁𝑃+3𝑁rep𝑁𝑃
SCH2, C	2𝑁𝑃+2𝑁𝑅𝑁𝑃log2𝑁𝑃+8𝐿h𝐿^′𝑁𝑅𝑁𝑇+4𝑁𝑇𝑁𝑅𝑁log2𝑁+4𝑁𝑅𝑁rep𝑁𝑃+43𝑁𝑅𝑁𝐼+19𝑁𝑃+𝐿c−1+𝐿^2c+6𝑁𝑃+3𝐿c𝑁𝑃+3𝑁rep𝑁𝑃
Hsu	2(𝑀ST−1)𝑁ST+44𝑁𝑁𝑇𝑁𝑅log28𝑁+3𝐿h𝑁𝑇(−1+4𝐿^2ℎ𝑁^2T+3𝑀LT𝑁LT𝑁𝑅+4𝑁𝑇𝐿h)+4𝑁𝑅𝑁TL+43𝑁𝑅1+𝑁𝐼9𝑀ST−1𝑁ST+𝐿c−1+𝐿^2c+6+3𝐿c𝑀ST−1𝑁ST+3𝑁TL