A simplified hard output sphere decoder for large MIMO systems with the use of efficient search center and reduced domain neighborhood study

EURASIP Journal on Wireless Communications and Networking

Table 3 ODN ZF-(O)SIC FNSA, ODN MMSE-(O)SIC FNSA, RDN LRA-ZF-(O)SIC FNSA, RDN LRA-MMSE-(O)SIC FNSA, and ML formulas

Technique designation	Corresponding computational complexity in MUL
ODN exact ZF-(O)SIC	\( 2MK{n}_{\mathrm{T}}^2+2MK{n}_{\mathrm{T}}-4MK+3M \)
ODN equivalent MMSE-(O)SIC	\( 2MK{n}_{\mathrm{T}}^2+2MK{n}_{\mathrm{T}}-4MK+3M \)
RDN exact LRA-ZF-(O)SIC	\( 2N \min \left\{K,N\right\}{n}_{\mathrm{T}}^2+30 \min \left\{K,N\right\}{n}_{\mathrm{T}}+2N\ \min \left\{K,N\right\}{n}_{\mathrm{T}}-4N \min \left\{K,N\right\} \)
RDN exact LRA-ZF-(O)SIC	\( +6 \min \left\{K,N\right\}{n}_{\mathrm{T}}^2+4 \min \left\{K,N\right\}{n}_{\mathrm{R}}{n}_{\mathrm{T}}+2 \min \left\{K,N\right\}{n}_{\mathrm{R}}+4{n}_{\mathrm{T}}^2-32 \min \left\{K,N\right\}+2N \)
RDN equivalent LRA-MMSE-(O)SIC	\( 2N \min \left\{K,N\right\}{n}_{\mathrm{T}}^2+30 \min \left\{K,N\right\}{n}_{\mathrm{T}}+2N\ \min \left\{K,N\right\}{n}_{\mathrm{T}}-4N \min \left\{K,N\right\} \)
RDN equivalent LRA-MMSE-(O)SIC	\( +6 \min \left\{K,N\right\}{n}_{\mathrm{T}}^2+4 \min \left\{K,N\right\}{n}_{\mathrm{R}}{n}_{\mathrm{T}}+2 \min \left\{K,N\right\}{n}_{\mathrm{R}}+4{n}_{\mathrm{T}}^2-32 \min \left\{K,N\right\}+2N \)
ML	\( 4{n}_{\mathrm{R}}{n}_{\mathrm{T}}{M}^{n_{\mathrm{T}}} \)