Wavelet Packet Code And Its Application In The Electrical Code Division Multiplexing Passive Optical Network

As one of the NG-PON technologies, the electrical code division multiplexing passive optical network(ECDM-PON) offers higher power budget due to the code gain, physical-layer based security due to dedicated code for specific user and scalability of coexisting with time division multiplexing(TDM) and wavelength division multiplexing(WDM). Meantime, it owns more mature coding technology and low system cost than optical code division multiplexing-PON(OCDM-PON).Based on wavelet packet transform theory, a wavelet packet code owning the characteristic of complete orthogonality is proposed in this paper. And The ECDM-PON coded by wavelet packet code is also established. Firstly, code pattern used in ECDM-PONs is introduced. Secondly, the generation principle of wavelet packet code is particularly explained, based on wavelet packet transform. Finally, the ECDM-PON system is simulated and experimentally demonstrated by using VPI. Under different number of access users, the performance of upstream and downstream transmission is simulated and analyzed. And it is also compared with ECDM-PON based on Walsh code in the aspects of bandwidth and optical beat noise suppression. The results show that wavelet packet code can reduce the optical bandwidth by about 40% compared to Walsh code at the transmitting terminal, and reduce 50% bandwidth of the best received filter. Furthermore, under optical beat noise, the proposed ECDM-PON exhibits longer transmission distances. By constructing the experimental platform the auto- and cross-correlation performance of the real signal coded by wavelet packet codes are analyzed. And the proposed ECDM-PON is experimentally verified, where 2-channels upstream at 625Mb/s/ch can be error free transmitted 40 km, and 8-channels downstream at 1.25Gb/s/ch can be error free transmitted 20 km.