Research on QC-LDPC Decoding Method With Low Quantization Word Length Based on Adaptive Information Mapping in Passive Optical Network

In this paper, we present a detailed and marketing - free study of all components of the upstream and downstream channel transmission overhead for Ethernet Passive Optical Networks (EPONs), excluding optional Forward Error Correction (FEC). First, the general Ethernet framing overhead is evaluated, followed by in depth analysis of each overhead component related to operation of the EPON MPCP protocol. Their overall impact on the performance of the system (especially in the upstream channel) is quantified for both best and worst case scenarios using typical system parameters, characteristic of standard EPON deployments. Based on a set of standard-based and typical EPON parameters, an estimated throughput of approximately 820 to 900 Mbit/s is available in the upstream direction, while in the downstream the effective throughput ranges from around 915 to 935 Mbit/s, producing the channel efficiency figures of 82 to 90% and 91.5 to 93.5% , respectively, relative to the effective data rate of 1 Gbit/s.

This document generally describes how to use Forward Error Correction (FEC) codes to efficiently provide and/or augment reliability for data transport. primary focus of this document is the application of FEC codes to one-to-many reliable data transport using IP multicast. This document describes what information is needed to identify a specific FEC code, what information needs to be communicated out-of-band to use the FEC code, and what information is needed in data packets to identify the encoding symbols they carry. procedures for specifying FEC codes and registering them with the Internet Assigned Numbers Authority (IANA) are also described. This document should be read in conjunction with and uses the terminology of the companion document titled, The Use of Forward Error Correction (FEC) in Reliable Multicast.

An FEC scheme combined with weighted scheduling to reduce multicast packet loss in IPTV over PON

Forward error correction (FEC) based on Reed–Solomon coding for the burst-mode upstream traffic of passive optical networks (PONs) is analyzed in detail using flexible field-programmable gate arrays (FPGAs). In order to achieve true burst-mode transmission using FPGAs, specific architectural solutions are required. In particular, a burst-mode frame synchronizer and a burstmode Reed–Solomon decoder are described in detail and analyzed experimentally within a state-of-the-art longreach PON test-bed. During this analysis, the upstream FEC performance is impaired by introducing strongly correlated and localized errors within the burst through the reduction of the burst preamble duration. The observed FEC degradation is exhaustively analyzed by implementing on the FPGAs a tool for error location analysis and frame loss measurements. This investigation demonstrates the importance of understanding the error distribution within the burst in order to correctly estimate the FEC performance in PON upstream links.

Real-time audio over a best-effort network, such as the Internet, frequently suffers from packet loss. To mitigate the impact of such packet loss, several research efforts and implementation studies advocate the use of forward error correction (FEC) coding. Although these prior works have pioneered promising and novel applications of to Internet audio, they do not definitively demonstrate the advantages of because they do not evaluate aggregate performance that results from multiplexing many like flows. We build on previous landmark works with a systematic study of for packet audio that characterizes the aggregate performance across all audio sources in the network. We refine the novel but ad hoc coding techniques proposed by Hardman, Sasse, Handley and Watson (see Proc. INET, 1995) into a formal framework that we call processing-based FEC (SFEC) and use our framework to more rigorously evaluate the relative merits of this approach. Through extensive simulation, we evaluate the scalability of SFEC for packet audio-i.e., the ability for a coding algorithm to improve aggregate performance when used by all sources in the network-and find that optimal signal quality is achieved when sources react to network congestion not by blindly adding FEC, but rather by adding in a controlled fashion that simultaneously constrains the source-coding rate. As a result, packet loss is mitigated without introducing more congestion, thus admitting a more scalable and effective approach than successively adding redundancy to a constant bit-rate source. While this result may seem intuitive, it has not been previously suggested in the context of Internet audio, and until now, has not been systematically studied.

The use of forward error correction (FEC) and multiple copy decoding (MCD) in point-to-multipoint automatic-repeat-request (ARQ) schemes is studied. Three different channel models are considered: a binary symmetric channel; a nonfading additive white Gaussian noise (AWGN) channel; and a Rayleigh fading AWGN channel. It is found that both FEC and MCD can yield significant throughput improvements. >

The performance of forward error correction (FEC) based on Reed-Solomon coding is analyzed experimentally for a burst-mode upstream channel within a passive optical network (PON) testbed. During this analysis, the upstream FEC performance is impaired by inducing correlated and localized errors within the burst through the injection of optical transients. These transients emulate the optical signal variation associated with the add-and-drop events of wavelength channels within a long-reach optical link based on a chain of erbium doped fiber amplifiers (EDFAs). The robustness of the FEC has been analyzed by measuring the post-FEC bit error rate (BER) as a function of the amplitude of the emulated transients and their delay with respect to the transmitted bursts. A margin of approximately 4dB is demonstrated for the transient amplitude before the FEC degradation. Furthermore, while the post-FEC BER is strongly degraded by the emulated transients, the pre-FEC BER stays below the FEC threshold, demonstrating the importance of measuring the post-FEC BER in order to correctly characterize the FEC performance in PON upstream channels affected by optical transients.

Power budget of direct-detection ultra-dense WDM-Nyquist-SCM PON with low-complexity SSBI mitigation

Wavelength division multiplexing/time division multiplexing (WDM/TDM) passive optical networks (PON) is being viewed as a promising solution for delivering multiple services and applications. The hybrid WDM / TDM PON uses the wavelength and bandwidth allocation strategy to control the distribution of the wavelength channels in the uplink direction, so that it can ensure the high bandwidth requirements of multiple Optical Network Units (ONUs) while improving the wavelength resource utilization. Through the investigation of the presented dynamic bandwidth allocation algorithms, these algorithms can't satisfy the requirements of different levels of service very well while adapting to the structural characteristics of mixed WDM / TDM PON system. This paper introduces a novel wavelength and bandwidth allocation algorithm to efficiently utilize the bandwidth and support QoS (Quality of Service) guarantees in WDM/TDM PON. Two priority based polling subcycles are introduced in order to increase system efficiency and improve system performance. The fixed priority polling subcycle and dynamic priority polling subcycle follow different principles to implement wavelength and bandwidth allocation according to the priority of different levels of service. A simulation was conducted to study the performance of the priority based polling in dynamic resource allocation algorithm in WDM/TDM PON. The results show that the performance of delay-sensitive services is greatly improved without degrading QoS guarantees for other services. Compared with the traditional dynamic bandwidth allocation algorithms, this algorithm can meet bandwidth needs of different priority traffic class, achieve low loss rate performance, and ensure real-time of high priority traffic class in terms of overall traffic on the network.

This paper presents the implementation of a photonics-assisted V-band 1 × 3 single-input multiple-output (SIMO) millimeter-wave wireless transmission system, achieving a transmission distance of 1.2 km. The system utilizes a dual-laser beating technique to generate a high-purity millimeter-wave carrier and incorporates offline digital signal processing (DSP) algorithms-including down-conversion, resampling, combination of Constant Modulus Algorithm (CMA) equalization and a Fractionally Spaced Equalizer (FSE), block phase search (BPS), and maximal ratio combining (MRC)-to achieve signal fusion and performance optimization among multiple receiving branches. Experimental results demonstrate that after maximal ratio combining, the signal's signal-to-noise ratio (SNR) is improved by approximately 5 dB, and the bit error rate (BER) is reduced by an order of magnitude, with the constellation diagram showing significant convergence, thereby enabling stable transmission without the use of forward error correction (FEC). To the best of our knowledge, this is the first experimental demonstration of high-gain performance achieved using these techniques in a V-band 1 × 3 SIMO millimeter-wave system.

In future broadband networks based on asynchronous transfer mode (ATM) transmission and switching technology, the dominant kind of impairment is expected to be packet (ATM cell) losses. The use of forward error correction (FEC) codes has been proposed as a way to overcome these losses. However, the maximum length of a lost packet string that a packet loss recovery scheme can be designed to recover highly depends upon the temporal behavior between the adjacent packet loss bursts. Thus, a realistic model for describing the packet loss process is needed. The Gilbert model proposed for such purpose turns out to be an unrealistic model, since it fails to consider some important characteristics during the packet loss process. A more realistic model is advanced in this paper.

In the case of orthogonal frequency-division multi-plexing (OFDM) systems, associated subcarriers can experience deep fades. When a cyclic prefix (CP) is used, CP-OFDM systems suffer from deep fading effects. With the channel coding and interleaving, coded OFDM provides a robust communication link for wireless channels. Coded CP-OFDM (COFDM) is one of the widely used transmission techniques for overcoming the deep fading of the channel and it tries to minimize deep fading problem by the use of forward error correction (FEC) techniques. Since it is known that the Coded CP-OFDM is not an exact solution to overcome the deep fading effect that degrades significantly the system performance, Coded generalized prefix (GP)-OFDM is proposed and also compared with coded CP-OFDM.

To provide Quality of Service (QoS) and data rate differentiation, we investigate in this paper a 2 dimensional optical code division multiple access (OCDMA) technique. A 2D multi-weight coding scheme with parallel mapping technique is developed. The system enhancement is assessed thanks to the use of Forward Error Correction (FEC) based on Low Density Parity Check (LDPC) codes. In order to have an efficient correction power, we develop an adaptation of the LDPC decoding algorithm to the specific multiple access interference distribution in a multimedia OCDMA network. The proposed network permits a high number of users to communicate with high data rates adapted to a multimedia transmission (voice, data and video) with corresponding QoS (10-3, 10-6, 10-9).

The exponential growth of high-speed broadband services, an increase in the number of end-users, high bandwidth, and massive data rate demand innovative and emerging points to a multipoint network that satisfies the need for next-generation passive optical access network (NG-PON). Next-generation passive optical access network stage 2 (NG-PON2)-based time and wavelength division multiplexing passive optical network (TWDM-PON) are mostly considered as the most promising optical access candidate due to its high-speed services, low power consumption, back-to-back compatibility, and cost-effectiveness. In this paper, the eight wavelengths-based bidirectional 80/20 Gbps TWDM-PON system using return to zero (RZ), non-return to zero (NRZ), and carrier suppressed return to zero (CSRZ) data modulation formats have been proposed and analyzed by varying input power, transmission distance, and bit rate. Further, the system is evaluated in terms of minimum bit error rate (BER), quality factor (Q factor), received optical power (dBm), eye diagrams, and eye height. It has been observed that the most appropriate modulation format for downstream transmission is NRZ while for upstream transmission, the most suitable modulation formats are RZ and NRZ.

The explosive development of emerging telecommunication services has stimulated a huge growth in bandwidth demand as people seek universal access to telecommunication networks. In addition, the kinds of services of an existing optical access network are becoming more flexible.The rapid expansion of Internet traffic shoves the communication networks to optical access networks for enhancing the transmission information rate. Passive optical network (PON) is a developed and most encouraging access network which provides the high bandwidth, information rate and low cost architecture for home and business enterprises. The main aim of this paper is to review the standardization evolution of PON to next generation passive optical network (NG-PON). Additionally, the literature review of PON and NG-PON based technologies are discussed. Also, it presents the possible challenges in NG-PON alongside their strengths and weakness in different techniques.