Networking and Communication Engineering

Prabhmandeep Kaur ¹, Divya Dhawan ¹

Affiliations
1 PEC University of Technology, Sector-12, Chandigarh, IN

Abstract

This paper presents a design approach for low-density parity-check (LDPC) encoder and decoder for applications in optical communication systems at 40 Gb/s. In order to get the best performance, the system is further optimized for the powers of the EDFA (Erbium Doped Fiber Amplifier) amplifiers used with the SMF (Single Mode Fiber) and DCF (Dispersion Compensating Fiber) fibers to achieve the highest Q factor. The designed LDPC coded system (using LDPC codes of r=0.8 for coding and sum-product algorithm (SPA) for decoding) is compared with the uncoded system at bit rate of 40 Gb/s and seen to provide significant performance improvement in terms of the BER. LDPC codes also provide near-capacity performance and significant system enhancement with respect to the state-of-the-art FEC (Forward Error Correction) schemes. High coding gains and their inherent low complexity of both the encoder and decoder have made them an attractive and viable choice for high-speed optical communication.

Keywords

Forward Error Correction (FEC), Low Density Parity Check (LDPC) Codes, Sum Product Algorithm (SPA).

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Divya Dhawan ¹, Neena Gupta ², Raj Bala ³

Affiliations
1 Department of Electronics and Electrical Communication Engineering, PEC University of Technology, Chandigarh, IN
2 Department of Electronics and Electrical Communication Engineering, PEC University of Technology, Chandigarh, IN
3 Punjab Engineering College, Chandigarh, IN

Abstract

Next generation services of triple play (data/voice/video) require far more bandwidth than prevailing technologies like dial-up, Integrated Services for Digital Network (ISDN), cable, Digital Subscriber Line (DSL) could offer. The bay between the access and metro networks is broadening due to bandwidth difference. This problem is termed as “access bottleneck”. The challenge is to distribute triple play services efficiently and cost effectively. Passive optical network has addressed these challenges in a most auspicious manner. This paper presents an architecture supporting triple play services. It employs Broadband Passive Optical Network (BPON) within last mile to address the access bottleneck issue. It uses orthogonal frequency division multiplexing (OFDM) for transmission of voice, video and data service. Performance analysis of our proposed architecture using simulation technique shows that the signal power received at the farthest Optical Network Unit (ONU) after passing through a distance of 25km is -25dBm with a satisfactory bit error rate (BER) of 10-3 and a Signal to Noise Ratio for video service, indicating good and clear picture quality. Proposed method not only accomplishes the desired requirement for availing services of data/voice/video (triple play) but also achieves its objective cost effectively.

Keywords

Broadband Passive Optical Network (BPON), Fiber to the Home (FTTH), Orthogonal Frequency Division Multiplexing (OFDM), PON (Passive Optical Network), Triple Play.

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Neena Gupta ¹, Divya Dhawan ¹, Preety Singla ²

Affiliations
1 Electronics and Electrical Communication (E&EC) Department, PEC University of Technology, Chandigarh, IN
2 Electronics and Electrical Communication (E&EC) Department, PEC University of Technology, Chandigarh, IN

Abstract

Free Space Optics (FSO) takes a line-of-sight approach in telecommunications, in which modulated infrared laser light is transmitted through the air. A need was felt to design FSO system having more powerful source, for longer transmission system as well as to tab the full potential of available optical bandwidth. In the previous work, authors used various OCDMA techniques for multiplexing to achieved a permissible BER > 10^-5and a speed less than 5 Gbps. This paper demonstrates the Optical Code Division Multiple Access Pseudo-orthogonal ―Flattened matrix codes in Free Space Optical Communication. In the present work authors design a system in which high speed information at 10 Gbps bit rate is successfully broadcasted from transmitter station to the receiver station at the link range of 500m through the Free Space channel at wavelength of 1550nm using an OCDMA pseudo-orthogonal encoder and decoder. The results are discussed in terms of bit error rate and quality factor with maximum number of users that can withstand by this communication system. This system can support sixteen simultaneous users and at an acceptable bit error rate e^-9 less.

Keywords

Bit Error Rate (BER), Free Space Optics (FSO), Optical Code Division Multiple Access (OCDMA), Pseudo-Orthogonal Codes.

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