Table 5 Complexity evaluation of the SISO demapper and SISO decoder in terms of number and type of arithmetic computations and memory access after normalization

SISO rotated demapper with a priori input

Computation units

Number and type of operations per modulated symbol per demapping iteration

Euclidean distance

358.75×2^{M + 1}Add(1,1) + load(28 + 2^{M + 4})

A priori adder

(2^M−2){7.5$E\left[\frac{M-1}{2}\right]$+ 8.5$E\left[\frac{M-1}{4}\right]$ + 9.5$E\left[\frac{M-1}{8}\right]$ + 24.5.M}Add(1,1) + load(8M) + load(M(2^M−2))

For QPSK 15M(2^M−2)Add(1,1) + load(8.M + M(2^M−2))

Minimum finder

(8 + 19.2^M)M Add(1,1) + store(8.M)

SISO double binary turbo decoder

Computation units

Number and type of operations per coded symbol per turbo decoding iteration

Branch metric

304Add(1,1) + load(100)

State metric

1040Add(1,1) + store(80)

Extrinsic information

760Add(1,1) + load(80) + store(50)