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Coding Techniques to Improve Bit Error Rate in Orthogonal Frequency Division Multiplexing System
Published in Rajeshree Raut, Ranjit Sawant, Shriraghavan Madbushi, Cognitive Radio, 2020
Rajeshree Raut, Ranjit Sawant, Shriraghavan Madbushi
One of the important mechanisms is to combine modulation scheme with forward error correcting (FEC) codes. A high data transmission speed is provided by a high-order modulation scheme, but it causes more susceptibility to interference. FEC code causes redundancy in the data transmission by repetition of some of the data bits, so bits that are missing or in error are corrected at the receiver end. This helps to reduce latency by cutting down the retransmissions. Without the FEC technique, we need whole frames to be retransmitted, which results in latency and lower QoS. There are three basic types of FEC codes: the block codes, the convolutional codes, and the turbo codes. In this section, the performance of the PHY layer of the WiMAX system is analyzed with and without turbo codes.
A Novel Comparative Study of Different Coding Algorithms and Implementation Issues through FPGA Technology for Wireless Vehicular Applications
Published in Fei Hu, Vehicle-to-Vehicle and Vehicle-to-Infrastructure Communications A Technical Approach, 2018
As described in the standard, the information bits must be randomized prior to their transmission. In this model, instead of performing this randomization process, there is usage of a ready block available in the software library. Data are randomly generated by the block of the random Bernoulli Binary Generator. There is usage of 480 samples per time unit for a data transmission rate of 3.0 Mbps and for a number of 20 OFDM symbols. The OFDM symbol time is 8.0 μs as derived from the standard, while the sample time value is 3.3333 × 10–7 sec in the case of QPSK modulation. This way there is parallel generation of the data to be transmitted and they are also randomized already. Following the generation of the data by the generator, the data are imported in a bus encoding subsystem. There, they will be initially encoded, sometimes by a turbo encoder and sometimes by an LDPC. This encoder has a fixed coding rate equal to ½ for all code and modulation cases. After the encoder the puncturing process is performed. This process aims at increasing the fixed encoding rate so as to achieve the desired total encoding rate of ½. Data interleaving is used to scatter the error bursts and thus increase the effectiveness of the forward error correction (FEC) previously used.
Network-Adaptive Rate and Error Controls for WiFi Video Streaming
Published in Ce Zhu, Yuenan Li, Advanced Video Communications over Wireless Networks, 2017
On the other hand, the error control–based adaptation addresses the reliable video transmission over the fading WiFi channels, which relies heavily on the coordinated protection effort in response to time-varying channel and source variations. In general, most of the existing error control schemes is are based on automatic repeat request (ARQ) and FEC (Sachs et al. 2001; Chan and Zheng 2006). The ARQ scheme represents a reactive error control that retransmits lost/corrupted packets depending upon explicit request(s) by the mobile nodes. However, ARQ should consider the feedback delay of request packets in the real-time video streaming. In comparison, the FEC scheme can be classified to several different proactive error controls that put some redundant information to video packets for error correction. Therefore, the FEC scheme requires additional overhead in the sense of data allocation and computational complexity, while it does not require additional feedback and retransmission.
FS-GDI Based Area Efficient Hamming (11, 7) Encoding
Published in International Journal of Electronics, 2023
Mohsen A. M. El-Bendary, O. El-Badry
In general, there are two main types of FEC schemes, the block and convolutional codes. The block codes such as Hamming codes, Reed-Solomon codes and Repetition codes are simpler than the Convolutional Codes (CCs). The CCs are widely used in the communications systems, it is more complex and consumes high amount of power. In this paper, Hamming (11, 7) encoding is presented, it is chosen of simplicity and as an example to study FS-GDI efficiency for implementing the error control coding schemes (R. P., K. P., and A. P., 2016; Shoba & Nakkeeran, 2017).
Performance analysis of LT code-based HARQ error control in underwater acoustic sensor networks
Published in Journal of Marine Engineering & Technology, 2022
P. Kaythry, R. Kishore, V. Nancy Priyanka
HARQ is a combination of FEC code and ARQ technique. FEC is mainly used to minimise the number of retransmissions from the source node to the receiving node. In this paper, RLT code is taken as FEC code due to its reduced encoding and decoding complexity. ARQ is mainly used for guarantee for reliable data delivery at the destination node. ARQ uses two types of packets namely ACK and NACK from the destination to the source.
On the Reliability of Industrial Internet of Things from Systematic Perspectives: Evaluation Approaches, Challenges, and Open Issues
Published in IETE Technical Review, 2022
Dong-Seong Kim, Tran-Dang Hoa, Huynh-The Thien
Redundancy at the physical layer allows IIoT devices to transmit redundant packet content and error correction codes [99–101]. There exist some works that have presented and investigated error correction codes for industrial networks in the literature. The results of evaluation analysis clearly show that two well-known error-control methods, Automatic Repeat reQuest (ARQ) and forward error correction (FEC) will improve the reliability of wireless communication significantly [102–106]. The ARQ mechanisms require a hand-shaking protocol to achieve reliable communication through sending acknowledgment to confirm the success of received packets. In contrast, the FEC-based techniques allow transmitters to send redundant data and the receivers recognizes and only receive a portion of the data without apparent errors. The fundamental of FEC allows expansion and modification of codes for specific applications. For example, the work described in [107] presents a lightweight error-correction scheme specially developed for IEEE 802.15.4-based IWSNs to guarantee backward compatibility with the standard. Simulation and real-time implementation have proved its effectiveness in correcting bit errors by guaranteeing to recover approximately 50% of data packets that would be lost without any error correction technique, thus showing its benefits in enhancing communication reliability to support process automation and remote maintenance applications completely in the reference scenario. Generally, FEC-based techniques use extra redundancy on transmission as compared to other error correction codes. However, a proposition in [108] introduces a better mechanism to improve the error correction capability (transmission reliability) with as much less redundancy as possible by exploiting the effectiveness of the multipath phenomenon. Accordingly, Reed-Solomon (RS) and Bose-Chaudhuri-Hocquenghem (BCH) codes with different parameters are used to provide high data-rate transmission and analyze the communication performance with and without multipath propagation [109].