1 Introduction
2 Proposed downlink chaos NOMA system
2.1 Structure of base station
2.1.1 Chaos modulation
2.1.2 User scheduling and non-orthogonal signal multiplexing
2.2 Decoding in receiver of user equipment
2.3 Calculation complexity during demodulation at UE
C-NOMA | C-OFDMA | BPSK-NOMA | BPSK-OFDMA | |
---|---|---|---|---|
Decoding computational complexities |
\( {\left({2}^{N_{\mathrm{t}}B}\right)}^{m_{\mathrm{s}}} \)
|
\( {2}^{N_{\mathrm{t}}B} \)
|
\( {2}^{N_{\mathrm{t}}{m}_{\mathrm{s}}}B \)
|
\( {2}^{N_{\mathrm{t}}}B \)
|
(24)2 = 28 | 24 | 24 × 2 = 25 | 22 × 2 = 23 |
3 Numerical results
Proposed downlink chaos NOMA scheme | |
---|---|
Cell layout | Hexagonal single-cell model |
No. of antennas | Nt = Nr = 2 |
No. of users K [/cell] | 8 |
Max. user multiplexing ms | 2 |
Power decay factor αFTPC | 0.0 (equal power allocation) |
No. of subcarrier Nc | 256 |
FFT size | 256 |
Channel | 16 pass 1 dB decayed quasi-static Rayleigh fading + AWGN |
Path loss exponent | 3.5 |
Standard deviation of shadowing loss [dB] | 7.0 |
Channel estimation | Ideal |
Scheduling algorithm | Proportional fairness |
MIMO block length | B = 2 |
Chaos modulation [bit/symbol/antenna] | 1 |
Chaos generation | Bernoulli shift map |
No. of chaos processing | Ite = 100 |
Chaos demodulation | MLSE |
Outer channel coding | None |
3.1 Transmission performances
3.2 Configuration of signal keys and chaos iteration number among users
Allocation pattern | ||
---|---|---|
Signal keys | No. of chaos processing | |
I | c00, 1 ≠ c00, 2 ≠ ⋯ ≠ c00, K | Ite1 = Ite2 = ⋯ = IteK = Ite |
II | c00, 1 = c00, 2 = ⋯ = c00, K | Iteh = Ite + 3(h − 1), (h = 1, ⋯, K) |
III | c00, 1 ≠ c00, 2 ≠ ⋯ ≠ c00, K | Iteh = Ite + 3(h − 1), (h = 1, ⋯, K) |
IV | c00, 1 = c00, 2 = ⋯ = c00, K | Ite1 = Ite2 = ⋯ = IteK = Ite |