Abstract
In this paper, we have theoretically analyzed that the existence of inter-subcarrier mixing interferences (ISMI) and frequency selective fading (FF) in the directed-detection optical orthogonal-frequency-division-multiplexing (DDO-OFDM) system will cause an unbalanced error distribution and degrade the system performance. Then we propose to employ the adaptive code rate technique (ACT) and bit interleaver in the DDO-OFDM system to combat ISMI and FF. The experimental results show that the receiver sensitivity of 5.9-Gb/s 64-ary quadrature-amplitude-modulation (64QAM) OFDM signal employing ACT(9.43 Gb/s after encoding) is improved more than 2 dB compared with the 5.9-Gb/s OFDM signal with 0.66 turbo coding rate (8.85 Gb/s after encoding) at the bit-error ratio (BER) of 1e-4. When the coding rate is all 0.625, the OFDM signal employing ACT has more than 1-dB gain improvement compared with the OFDM signal encoded with fixed-rate turbo coding. And additional ∼1-dB receiver sensitivity improvement is enabled when the OFDM signal employ ACT and bit-interleaver simultaneously.
| Original language | English |
|---|---|
| Pages (from-to) | 35-39 |
| Number of pages | 5 |
| Journal | Optical Fiber Technology |
| Volume | 19 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 2013 |
| Externally published | Yes |
Keywords
- Adaptive code rate technique (ACT)
- Bit interleaver
- Direct detection (DD)
- Optical fiber communication
- Orthogonal frequency division multiplexing (OFDM)