Optimizing LDPC and BCH Forward Error Correction for Improved Reliability and Reduced Bit Errors in Low-SNR DVB-T2 Transmission Environments

In this work, a concatenated forward error correction (FEC) scheme together with Orthogonal Frequency Division Multiplexing (OFDM) have been used for effective transmission of data/images over additive and fading channels. With a Bose Chaudhuri Hocquenghem (BCH) code as the outer code and a Low Density Parity Check (LDPC) code as the inner code, the transmission has been simulated over both the Gilbert-Elliot and ITU Rayleigh fading channels. The FEC parameters assumed throughout the simulations were obtained from the DVB-T2 standard and the Base Band (BB) frames were created by making use of shortening and zero-padding concepts. The results which have been presented in terms of BER and psycho-visual performances show the resilience of the FEC schemes and OFDM to channel impairments. The BER performances attained over the Gilbert-Elliot Channel (a channel that introduces burst errors when in the bad state) using LDPC only and BCH-LDPC concatenated coding indicated that the outer BCH coding will start to achieve a much lower BER after an SNR of 5 dB. Over the ITU-A Rayleigh fading channel it was observed that the performance increment due to the outer BCH encoder only become apparent after 6 dB when compared to the rate ¼ LDPC only coded system BER performance. Over the Gilbert-Elliot channel a BCH-LDPC coded QPSK-OFDM system would provide a BER of 3×10−4 at 6 dB while the same BER for the ITU Vehicular-A channel was possible at 6.6 dB.

Modified Packet Combining (MPC) scheme is an error correction scheme, which can correct double or, higher bit errors. In some earlier work, a scheme known as Packet Reversed Packet Combining (PRPC) scheme that will correct error if occurs at same bit location of erroneous copies, was studied. Both PRPC and MPC scheme are believed to offer higher throughput and better error correction capability at high bit error rate (BER) and large packet size only. Exact analysis was performed to substantiate this claim of higher throughput and better error correction capability in high as well as in low bit error rate (BER) for large and medium packet size. To combat high bit error rate some researches proposed to use Error Correction Code (ECC) in place of Error Detection Code (EDC) in ARQ scheme. But no conclusive result is found to justify the idea in terms of throughput. The current investigation is an attempt to explore the basic gap. In this paper, we investigate the exact analysis of both PRPC and MPC in a Modified way over Conventional PRPC, and report the findings thereof. We propose a combined protocol of Modified PRPC and MPC, and find that it will offer higher throughput and better error correction capability at high and low BER with medium and large packet size as we have used MPC (Modified Packet Combining) scheme with PRPC (Packet Reverse Packet Combining) scheme in a Modified way by combining BEC (Backward Error Correction) with FEC (Forward Error Correction) Codes for Mobile Communication and Networks.

In this paper, we use post processing methods to compensate the bit errors occurred in watermark embedding and extracting. Forward error correction (FEC)-based and chirp-based techniques are applied to encode and shape the embedded watermark message so that even at the presence of some bit error rates (BERs) in the extracted watermark, the watermarking algorithm be able to successfully estimate the correct embedded watermark message. Repetition and Bose-Chaudhuri-Hocquenghem (BCH) codings are used as two well-known FEC schemes, and discrete polynomial transform (DPPT) and Hough-Radon transform (HRT) are utilized as two chirp detectors in chirp-based watermarking. Robustness of all the proposed post processing methods are tested for checkmark benchmark attacks, and we found that the chirp-based watermarking using the DPPT chirp detector offers the highest watermark extraction rate, and the best bit error compensation even at BERs of higher than 17%.

This paper investigates the effects of noise‐induced transmission errors on the performance of compression coding methods for still pictures. The following four coding methods are considered: (1) adaptive cosine transform coding; (2) DPCM coding; (3) adaptive block coding; and (4) vector quantization coding. First, the relations among the bit error rate, signal‐to‐noise ratio (SNR), and code lengths by these coding methods are compared in the case of transmission without error control. Adaptive cosine transform coding and adaptive block coding require control information for adaptivity; therefore, they are investigated with and without transmission errors in the coding control information. Further, transmission with error control is studied for sending control information. Considering the error control methods, both automatic repeat request and forward error correction are considered. In these cases SNR deterioration by transmission noise beyond error correction capability and the amount of additional data required for error detection/correction or retransmission are examined. BCH codes are used for error detection and correction.

In this chapter, forward error correction (FEC) techniques for optical communications are described. In Sect. 17.1, the basic concepts of FEC and its terminology are explained. The various FECs developed to date for optical communications are classified as belonging to three generations. In Sect. 17.2, the first-generation FEC represented by RS(255,239) is described. The second-generation FECs are explained in Sect. 17.3, where recently developed concatenated codes are discussed. In Sect. 17.4, the third-generation FECs, which are more powerful FECs based on soft-decision decoding, are analyzed in detail. A block turbo code and low-density parity-check (LDPC) codes showing a record NCG of around 10 dB are discussed in detail. In Sect. 17.5, we compare each generation of FEC with the Shannon limit. The ultimate NCG is discussed as a function of code rate. FEC error count and its application are discussed in Sect. 17.6.

In Japan, the next generation of Integrated Services Digital Broadcasting — Terrestrial (ISDB-T) system is being developed for transmission of large-volume content services such as ultra high definition television (UHDTV). The system uses low density parity check (LDPC) code as the forward error correction (FEC) to improve its robustness. In particular, the performance of the system's FEC should be evaluated not only in additive white Gaussian noise (AWGN) environments, but also in multipath environments. Moreover, it would be desirable for the new FEC to have better performance than the previous one even in multipath environments. Previous research evaluated the transmission performance of LDPC code by using computer simulations of the propagation model. The actual propagation characteristics were not evaluated. In this paper, we describe the transmission performance of convolutional coded orthogonal frequency division multiplexing (CC-OFDM) and LDPC coded OFDM (LDPC-OFDM) in computer simulations using the same OFDM frame structure and propagation channels as measured in an outdoor experiment conducted in an urban area. We show that LDPC code outperforms CC in multipath environments and how the transmission performance depends on the code rate. In addition, we analyze the correlation between transmission performance and propagation channels.

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.

The remarkable development of mobile networks has enabled ubiquitous communications that has transformed the way people connect with each other. Meanwhile, the growing adoption of smartphones, tablets, and increasingly bandwidth-intensive applications and services is driving unprecedented mobile broadband traffic growth; therefore, finding state-of-the-art strategies for improving the wireless transmission reliability has emerged significantly. In particular, to enable significant mitigation of the detrimental effects of multipath fading, high-performance forward error correction (FEC) techniques have now recognized to become a vital part of modern digital wireless systems. This work is dedicated to address a class of high-performance iteratively decoded FECs referred to as serial concatenation of quadratic interleaved codes (SCQICs) wherein the reordering arrays for permutor and unscramble in the FEC encoding/decoding entities enjoy the remarkable algorithm proposed by Takeshita et al. seminal contribution which: (1) yields provisioning coding gain in both waterfall and error-floor regions of the bit error rate (BER) performance curve (2) enables possibility of analysis and compact representation, (3) requires straightforward implementation. We have observed that their utilization for the modern wireless communications applications remained scarce due to the lack of strong and comprehensive performance predictions over the different statistical wireless channel models. Hence, in this paper, we endeavor to analyze and examine the error-correction capability of SCQICs vastly from the various aspects, and investigate their resultant coding gains in different wireless Doppler environments.

Irreducible polynomials play an important role in design of Forward Error Correction (FEC) codes for data transmission with integrity and automatic correction of data, as for example, Low-Density Parity Check codes. The usage of irreducible polynomials enables construction of non-prime-order finite fields. Most of the irreducible polynomials belong to binary Galois field. The important analytical concept is optimisation of irreducible polynomials for use in FECs in nonbinary Galois (NBG) field, leading to the development of an algorithm for LDPC that can work with nonbinary Galois fields. According to studies, the Tanner graph for ‘nonbinary Low Density Parity Check’ codes might get sparser as the field’s dimensions rise, ensuring that they do much better than their binary counterparts. A detailed discussion of representation of nonbinary irreducible polynomial and the computations involved have been illustrated. The concept has been tried for NB-LDPC codes. To prove the notion, computational complexity is found from different parameters such as performance of error correction capability, complexity cost and simulation time taken. Such detail study makes the NBG fields-based FEC very suitable for high-speed data transmission with self-error correction.

With the volumes of transmitted information growth, the task of increasing the noise immunity and reliability of data transmission networks arises. The presence of interference such as nonlinear loss, chromatic dispersion, polarization mode dispersion, and inter-channel interference decreases the performance of fiber optical communication systems. Forward Error Correction (FEC) codes are vital in optical communication systems to achieve highly efficient and highly reliable communication. The paper presents research on a simulation model where FEC channel-coding schemes based on the Bose-Chaudhuri-Hocquenghem (BCH) cycling block code are integrated with non-return-to-zero on-off-keying (NRZ-OOK) modulated wavelength division multiplexed (WDM) fiber optical communication systems. The results highlight the selection of coding parameters in the adopted FEC approach. In our paper, the BCH (255, 231), BCH (255, 223), and BCH (255,191) FEC channel-coding schemes are chosen for integration in the NRZ-OOK modulated WDM optical transmission system. The paper shows the main advantages and drawbacks of the selected FEC coding scheme and provides a comparison of the proposed schemes based on their main features, such as bit error ratio (BER), which were obtained through the simulations of 25 Gbit/s NRZ-OOK WDM fiber optical system. The dynamics of changes in BER was investigated using the Monte Carlo (MC) method for precise results. The paper shows that integration of FEC channel-coding schemes based on the BCH codes improves the noise immunity and reliability of the WDM Fiber Optical Communication Systems.

Tel-USat is an underdevelopment CubeSat of Telkom University. The satellite consists of various subsystems. Telemetry, Tracking and Command (TTC) is one of satellite subsystem which is used to transmits the housekeeping data of the satellite and periodically sends beacon signal to the earth. However, the satellite communication system is a long-distance communication so that any disturbance, interference, and attenuation of communication channels are possible to disrupt the data. Therefore, an Error Detection and Control (EDAC) or Forward Error Correction (FEC) is implemented to control and minimise errors without the need for re-transmission. This work has designed and developed the prototype of the TTC subsystem integrated with the AX.25 protocol as EDAC and the BCH (63.45) coding method as FEC. The BCH used in this research is capable to correct a maximum of 3 bits per frame. Moreover, the BCH code can reduce the Eb/No needed to get the corresponding BER value that equal to 10^-6. The Eb/No peak value reduces from −6.56 dBm to −12.71 dBm using BCH coding with the 4-FSK modulation. The range test was performed to ensure the functionality of the prototype with the highest success rate in 1200kBaud and −30 dBm configuration at approximately 80 metres.

Low-density parity checks (LDPC) codes are considered good performance error correction codes. However, decoder complexity increases with increasing code length. In this study, we introduce short-length serially concatenated LDPC codes. The proposed technique uses pairs of compatible LDPC codes that act as outer and inner serially concatenated codes. In this code pair, the inner code takes input that is the same length as the outer LDPC encoder output. This study examined two cases of LDPC codes as compatible pairs with low numbers of iterations and compared bit error rate (BER) performance to a standalone LDPC code with an additive white Gaussian noise channel. We also considered the quadrature phase shift keying QPSK, 16-quadrature amplitude modulation (QAM), and 64-QAM system modulation schemes. Simulation results demonstrate that the proposed system has good BER performance compared to a standalone LDPC code, the results summarized in table and performance curves.

Multi carrier code division multiple access (MC-CDMA), a strong contender for future mobile communication is a combination of orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA). Turbo coding technique can be used for improving the performance of MC-CDMA system in terms of bit error rate (BER). The objective of this work is to form a coding scheme that reduces BER of MC-CDMA system. In this paper a time domain turbo block code (TBC) designed using powerful low density parity check (LDPC) code is used in MC-CDMA system for improving the BER performance and the same is proved through simulation. This code also has error correction capability along with high performance efficiency in terms of BER.

Cell rate moderation of VBR video under an FEC environment in ATM networks

In this paper we evaluate the performance of forward error correction (FEC) techniques in the presence of four wave mixing (FWM) and dispersion induced inter-symbol interference (ISI). A comparison with the detuning technique [1] is also presented, for the case of FWM penalty mitigation. FEC has been widely used in long haul submarine optical transmission systems, both repeated [2] and unrepeated [3] and its performance in the presence of polarization mode dispersion (PMD) has also been investigated [4,5]. The influence of non-linearities on optical systems that use FEC has recently been reported [6].