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Calculated Shard: 103 (from laksa166)

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curl -X POST \
  'http://laksa103.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://www.geeksforgeeks.org/computer-networks/error-correction-in-computer-networks/\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.geeksforgeeks.org/computer-networks/error-correction-in-computer-networks/\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.geeksforgeeks.org\/computer-networks\/error-correction-in-computer-networks\/","crawl_time":1775603296,"first_indexed_time":1751461603,"http_code":200,"src_unparsed":"org,geeksforgeeks!www,\/computer-networks\/error-correction-in-computer-networks\/ s443","src_root_hash":"12046344915360636903","history_drop_reason":null,"meta_title":"Error Correction in Computer Networks - GeeksforGeeks","meta_descriptions":["Your All-in-One Learning Portal: GeeksforGeeks is a comprehensive educational platform that empowers learners across domains-spanning computer science and programming, school education, upskilling, commerce, software tools, competitive exams, and more.","Your All-in-One Learning Portal. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice\/competitive programming\/company interview Questions."],"attrs_boilerpipe_text":"Last Updated :\n9 Jan, 2026\nError correction is the process of detecting and fixing errors that occur during data transmission so that the receiver can correctly understand the received data. Errors may happen due to noise, interference, or other transmission issues. Error correction techniques help maintain data integrity and ensure reliable communication between network devices. These techniques allow the system to recover correct information even when some transmitted bits are corrupted.\nForward Error Correction (FEC):\nForward Error Correction is an error control technique used during data transmission.\nThe sender adds extra (redundant) bits to the original data before sending it.\nThese extra bits help the receiver detect and correct errors on its own.\nThe receiver does not need to request retransmission from the sender.\nThis reduces delay and improves communication reliability.\nFEC is useful where retransmission is costly or not possible.\nIt is commonly used in wireless networks, satellite communication, and multimedia streaming.\nHamming Code is a simple and common example of a Forward Error Correction technique.\nBackward Error Correction:\nBackward Error Correction is an error control technique used in data communication.\nThe receiver checks the received data for errors using error detection methods.\nIf an error is found, the receiver sends a retransmission request to the sender.\nThe sender retransmits the corrupted data until it is received correctly.\nThis method requires a feedback channel between the sender and receiver.\nIt provides reliable data delivery but can increase transmission delay.\nBackward Error Correction is commonly implemented using Automatic Repeat Request (ARQ) techniques.\nCommon ARQ methods include Stop-and-Wait, Go-Back-N, and Selective Repeat.\nTypes of Forward Error Correction (FEC)\nHamming Code\nHamming Code is a Forward Error Correction (FEC) technique used to make data transmission more reliable. It allows the receiver to detect and correct errors on its own without asking the sender to resend the data.\nHamming Code can correct one-bit errors and detect two-bit errors, but it cannot fix two errors at the same time.\nIt is suitable for systems where errors are rare and usually occur one bit at a time.2. Reed–Solomon Code\nParity bits are placed at positions 1, 2, 4, 8, 16, …, which are powers of two.\nEach parity bit checks a specific group of data bits, helping locate the exact position of an error.\nThe receiver uses parity checks (syndrome) to identify the incorrect bit and correct it if needed.\nSince the receiver can fix the error by itself, no retransmission is required, making it a true Forward Error Correction technique.\nReed–Solomon Code\nReed–Solomon Code is a block-based Forward Error Correction (FEC) technique widely used in digital communication and data storage systems. It works on symbols instead of individual bits, where each symbol contains multiple bits. Because of this symbol-based approach, Reed–Solomon codes are very effective at correcting burst errors, in which many consecutive bits are damaged during transmission or storage.\nSymbol-based working:\nReed–Solomon codes work on data blocks made of symbols, where each symbol contains multiple bits. Extra parity symbols are added to the block for error correction.\nMultiple error correction:\nThe number of errors that can be corrected depends on the extra symbols added. If 2t redundant symbols are used, the code can correct up to t corrupted symbols in a block.\nStronger than bit-level codes:\nSince errors are corrected at the symbol level, Reed–Solomon is more powerful than simple methods that correct only single-bit errors.\nVery effective for burst errors:\nBurst errors usually damage several consecutive bits, often affecting full symbols. Reed–Solomon codes are designed to recover such damaged symbols accurately.\nWide practical usage:\nThese codes are widely used in CDs, DVDs, Blu-ray discs, QR codes, barcodes, satellite communication, and digital TV, where data accuracy is critical.\nHigher computation cost:\nReed–Solomon codes need more complex encoding and decoding compared to simpler techniques like Hamming Code, but this complexity provides better error correction strength.\nTypes of Backward Error Correction\nStop-and-Wait ARQ\nStop-and-Wait ARQ is a basic Backward Error Correction method for reliable data transmission.\nThe sender transmits one frame at a time and waits for an acknowledgment (ACK) from the receiver.\nThe receiver sends an ACK only if the frame is received correctly, ensuring reliable delivery.\nIf a frame is lost, contains errors, or the ACK is not received, the sender retransmits the same frame.\nA timer is used for each frame; if it expires before receiving an ACK, the frame is resent.\nThis method is simple and reliable, but inefficient for high-speed or long-delay networks due to idle waiting time.\nGo-Back-N ARQ\nGo-Back-N ARQ is a Backward Error Correction method that allows the sender to transmit multiple frames consecutively without waiting for individual acknowledgments.\nIt uses a sliding window at the sender to control how many frames can be sent before receiving ACKs.\nThe receiver accepts frames only in order; out-of-order frames are discarded even if they are correct.\nThe receiver sends cumulative acknowledgments indicating the highest in-order frame received successfully.\nIf a frame is lost or corrupted, the sender retransmits that frame and all subsequent frames in the window.\nGo-Back-N improves throughput over Stop-and-Wait but can waste bandwidth if errors occur frequently.\nApplications of Error Correction\nWireless and Mobile Communication (4G\/5G, Wi-Fi):\nError correction ensures reliable data transmission over wireless channels, which are prone to interference, fading, and noise.\nTechniques like Convolutional Codes, Turbo Codes, and LDPC codes are commonly used in 4G\/5G networks and Wi-Fi to improve throughput and reduce packet loss.\nSatellite and Deep-Space Communication:\nCommunication over long distances, such as satellite links or deep-space probes, experiences significant signal attenuation and delays.\nForward Error Correction methods like Reed–Solomon and Convolutional Codes allow receivers to correct errors without relying on retransmissions, which are impractical due to high latency.\nData Storage Devices (HDD, SSD, CDs, DVDs):\nError correction ensures the integrity of stored data, compensating for physical defects, scratches, or degradation over time.\nCodes such as Hamming Code, Reed–Solomon, and BCH codes are embedded in storage devices to detect and correct errors automatically.\nQR Codes, Barcodes, and Digital Broadcasting:\nQR codes and barcodes use error correction (typically Reed–Solomon) to recover data if part of the code is damaged or obscured.\nDigital TV, radio, and streaming services implement FEC techniques to maintain high-quality transmission even in noisy environments.","attrs_markdown":"[![geeksforgeeks](https:\/\/media.geeksforgeeks.org\/gfg-gg-logo.svg)](https:\/\/www.geeksforgeeks.org\/)\n\n![search icon](https:\/\/media.geeksforgeeks.org\/auth-dashboard-uploads\/Property=Light---Default.svg)\n\n- Sign In\n- [Courses]()\n- [Tutorials]()\n- [Interview Prep]()\n\n- [CN Tutorial](https:\/\/www.geeksforgeeks.org\/computer-networks\/computer-network-tutorials\/)\n- [Interview Questions](https:\/\/www.geeksforgeeks.org\/computer-networks\/commonly-asked-computer-networks-interview-questions-set-1\/)\n- [Quizzes](https:\/\/www.geeksforgeeks.org\/quizzes\/50-computer-networks-mcqs-with-answers\/)\n- [Gate](https:\/\/www.geeksforgeeks.org\/computer-networks\/computer-networks-for-gate\/)\n- [OSI Model](https:\/\/www.geeksforgeeks.org\/computer-networks\/open-systems-interconnection-model-osi\/)\n- [TCP-IP](https:\/\/www.geeksforgeeks.org\/computer-networks\/tcp-ip-model\/)\n- [Network Security](https:\/\/www.geeksforgeeks.org\/computer-networks\/network-security\/)\n- [COA](https:\/\/www.geeksforgeeks.org\/computer-organization-architecture\/computer-organization-and-architecture-tutorials)\n- [TOC](https:\/\/ww\\)w.geeksforgeeks.org\/theory-of-computation\/introduction-of-theory-of-computation\/)\n- [Compiler Design](https:\/\/www.geeksforgeeks.org\/compiler-design\/compiler-design-tutorials\/)\n\n# Error Correction in Computer Networks\nLast Updated : 9 Jan, 2026\n\nError correction is the process of detecting and fixing errors that occur during data transmission so that the receiver can correctly understand the received data. Errors may happen due to noise, interference, or other transmission issues. Error correction techniques help maintain data integrity and ensure reliable communication between network devices. These techniques allow the system to recover correct information even when some transmitted bits are corrupted.\n\n### Forward Error Correction (FEC):\n- Forward Error Correction is an error control technique used during data transmission.\n- The sender adds extra (redundant) bits to the original data before sending it.\n- These extra bits help the receiver detect and correct errors on its own.\n- The receiver does not need to request retransmission from the sender.\n- This reduces delay and improves communication reliability.\n- FEC is useful where retransmission is costly or not possible.\n- It is commonly used in wireless networks, satellite communication, and multimedia streaming.\n- Hamming Code is a simple and common example of a Forward Error Correction technique.\n### Backward Error Correction:\n- Backward Error Correction is an error control technique used in data communication.\n- The receiver checks the received data for errors using error detection methods.\n- If an error is found, the receiver sends a retransmission request to the sender.\n- The sender retransmits the corrupted data until it is received correctly.\n- This method requires a feedback channel between the sender and receiver.\n- It provides reliable data delivery but can increase transmission delay.\n- Backward Error Correction is commonly implemented using Automatic Repeat Request (ARQ) techniques.\n- Common ARQ methods include Stop-and-Wait, Go-Back-N, and Selective Repeat.\n## Types of Forward Error Correction (FEC)\n### Hamming Code\nHamming Code is a Forward Error Correction (FEC) technique used to make data transmission more reliable. It allows the receiver to detect and correct errors on its own without asking the sender to resend the data.\n\n- Hamming Code can correct one-bit errors and detect two-bit errors, but it cannot fix two errors at the same time.\n- It is suitable for systems where errors are rare and usually occur one bit at a time.2. Reed–Solomon Code\n- Parity bits are placed at positions 1, 2, 4, 8, 16, …, which are powers of two.\n- Each parity bit checks a specific group of data bits, helping locate the exact position of an error.\n- The receiver uses parity checks (syndrome) to identify the incorrect bit and correct it if needed.\n- Since the receiver can fix the error by itself, no retransmission is required, making it a true Forward Error Correction technique.\n### Reed–Solomon Code\nReed–Solomon Code is a block-based Forward Error Correction (FEC) technique widely used in digital communication and data storage systems. It works on symbols instead of individual bits, where each symbol contains multiple bits. Because of this symbol-based approach, Reed–Solomon codes are very effective at correcting burst errors, in which many consecutive bits are damaged during transmission or storage.\n\n- ****Symbol-based working:**** Reed–Solomon codes work on data blocks made of symbols, where each symbol contains multiple bits. Extra parity symbols are added to the block for error correction.\n- ****Multiple error correction:**** The number of errors that can be corrected depends on the extra symbols added. If 2t redundant symbols are used, the code can correct up to t corrupted symbols in a block.\n- ****Stronger than bit-level codes:**** Since errors are corrected at the symbol level, Reed–Solomon is more powerful than simple methods that correct only single-bit errors.\n- ****Very effective for burst errors:**** Burst errors usually damage several consecutive bits, often affecting full symbols. Reed–Solomon codes are designed to recover such damaged symbols accurately.\n- ****Wide practical usage:**** These codes are widely used in CDs, DVDs, Blu-ray discs, QR codes, barcodes, satellite communication, and digital TV, where data accuracy is critical.\n- ****Higher computation cost:**** Reed–Solomon codes need more complex encoding and decoding compared to simpler techniques like Hamming Code, but this complexity provides better error correction strength.\n## Types of Backward Error Correction\n### Stop-and-Wait ARQ\n- Stop-and-Wait ARQ is a basic Backward Error Correction method for reliable data transmission.\n- The sender transmits one frame at a time and waits for an acknowledgment (ACK) from the receiver.\n- The receiver sends an ACK only if the frame is received correctly, ensuring reliable delivery.\n- If a frame is lost, contains errors, or the ACK is not received, the sender retransmits the same frame.\n- A timer is used for each frame; if it expires before receiving an ACK, the frame is resent.\n- This method is simple and reliable, but inefficient for high-speed or long-delay networks due to idle waiting time.\n### Go-Back-N ARQ\n- Go-Back-N ARQ is a Backward Error Correction method that allows the sender to transmit multiple frames consecutively without waiting for individual acknowledgments.\n- It uses a sliding window at the sender to control how many frames can be sent before receiving ACKs.\n- The receiver accepts frames only in order; out-of-order frames are discarded even if they are correct.\n- The receiver sends cumulative acknowledgments indicating the highest in-order frame received successfully.\n- If a frame is lost or corrupted, the sender retransmits that frame and all subsequent frames in the window.\n- Go-Back-N improves throughput over Stop-and-Wait but can waste bandwidth if errors occur frequently.\n## Applications of Error Correction\n### ****Wireless and Mobile Communication (4G\/5G, Wi-Fi):****\n- Error correction ensures reliable data transmission over wireless channels, which are prone to interference, fading, and noise.\n- Techniques like Convolutional Codes, Turbo Codes, and LDPC codes are commonly used in 4G\/5G networks and Wi-Fi to improve throughput and reduce packet loss.\n### ****Satellite and Deep-Space Communication:****\n- Communication over long distances, such as satellite links or deep-space probes, experiences significant signal attenuation and delays.\n- Forward Error Correction methods like Reed–Solomon and Convolutional Codes allow receivers to correct errors without relying on retransmissions, which are impractical due to high latency.\n### ****Data Storage Devices (HDD, SSD, CDs, DVDs):****\n- Error correction ensures the integrity of stored data, compensating for physical defects, scratches, or degradation over time.\n- Codes such as Hamming Code, Reed–Solomon, and BCH codes are embedded in storage devices to detect and correct errors automatically.\n### ****QR Codes, Barcodes, and Digital Broadcasting:****\n- QR codes and barcodes use error correction (typically Reed–Solomon) to recover data if part of the code is damaged or obscured.\n- Digital TV, radio, and streaming services implement FEC techniques to maintain high-quality transmission even in noisy environments.\n\nSuggested Quiz\n\n![reset](https:\/\/media.geeksforgeeks.org\/auth-dashboard-uploads\/Reset-icon---Light.svg)\n\n4 Questions\n\nIn Forward Error Correction (FEC), which of the following is TRUE?\n\n- A\n  \n  Errors are corrected by retransmissions from sender\n- B\n  \n  Receiver corrects errors without asking sender to resend\n- C\n  \n  Both sender and receiver retransmit corrupted data\n- D\n  \n  Errors cannot be corrected, only detected\n\nBackward Error Correction relies on:\n\n- A\n  \n  Receiver correcting the bit pattern directly\n- B\n  \n  Sender retransmitting when errors are detected\n- C\n  \n  No acknowledgment mechanism\n- D\n  \n  Receiver predicting missing bits\n\nIn Hamming Code, redundant bits are placed at positions:\n\n- A\n  \n  Odd positions only\n- B\n  \n  Prime-number positions\n- C\n  \n  Positions that are powers of 2\n- D\n  \n  Last positions of the message\n\nThe number of redundant bits ‘r’ needed to protect ‘d’ data bits in Hamming Code satisfies:\n\n- A\n  \n  2^r ≥ d + r + 1\n- B\n  \n  2r ≥ d\n- C\n  \n  r = log₂(d)\n- D\n  \n  2^(d+r) ≥ r\n\n![success](https:\/\/media.geeksforgeeks.org\/auth-dashboard-uploads\/sucess-img.png)\n\nQuiz Completed Successfully\n\nYour Score :0\/4\n\nAccuracy :0%\n\nLogin to View Explanation\n\n**1**\/4\n\n\\< Previous\n\nNext \\>\n\nComment\n\n[T](https:\/\/www.geeksforgeeks.org\/user\/tarakki100\/)\n\n[tarakki100](https:\/\/www.geeksforgeeks.org\/user\/tarakki100\/)\n\n4\n\nArticle Tags:\n\nArticle Tags:\n\n[Computer Networks](https:\/\/www.geeksforgeeks.org\/category\/computer-subject\/computer-networks\/)\n\n[Geeks Premier 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Errors may happen due to noise, interference, or other transmission issues. Error correction techniques help maintain data integrity and ensure reliable communication between network devices. These techniques allow the system to recover correct information even when some transmitted bits are corrupted.\n\n### Forward Error Correction (FEC):\n- Forward Error Correction is an error control technique used during data transmission.\n- The sender adds extra (redundant) bits to the original data before sending it.\n- These extra bits help the receiver detect and correct errors on its own.\n- The receiver does not need to request retransmission from the sender.\n- This reduces delay and improves communication reliability.\n- FEC is useful where retransmission is costly or not possible.\n- It is commonly used in wireless networks, satellite communication, and multimedia streaming.\n- Hamming Code is a simple and common example of a Forward Error Correction technique.\n### Backward Error Correction:\n- Backward Error Correction is an error control technique used in data communication.\n- The receiver checks the received data for errors using error detection methods.\n- If an error is found, the receiver sends a retransmission request to the sender.\n- The sender retransmits the corrupted data until it is received correctly.\n- This method requires a feedback channel between the sender and receiver.\n- It provides reliable data delivery but can increase transmission delay.\n- Backward Error Correction is commonly implemented using Automatic Repeat Request (ARQ) techniques.\n- Common ARQ methods include Stop-and-Wait, Go-Back-N, and Selective Repeat.\n## Types of Forward Error Correction (FEC)\n### Hamming Code\nHamming Code is a Forward Error Correction (FEC) technique used to make data transmission more reliable. It allows the receiver to detect and correct errors on its own without asking the sender to resend the data.\n\n- Hamming Code can correct one-bit errors and detect two-bit errors, but it cannot fix two errors at the same time.\n- It is suitable for systems where errors are rare and usually occur one bit at a time.2. Reed–Solomon Code\n- Parity bits are placed at positions 1, 2, 4, 8, 16, …, which are powers of two.\n- Each parity bit checks a specific group of data bits, helping locate the exact position of an error.\n- The receiver uses parity checks (syndrome) to identify the incorrect bit and correct it if needed.\n- Since the receiver can fix the error by itself, no retransmission is required, making it a true Forward Error Correction technique.\n### Reed–Solomon Code\nReed–Solomon Code is a block-based Forward Error Correction (FEC) technique widely used in digital communication and data storage systems. It works on symbols instead of individual bits, where each symbol contains multiple bits. Because of this symbol-based approach, Reed–Solomon codes are very effective at correcting burst errors, in which many consecutive bits are damaged during transmission or storage.\n\n- ****Symbol-based working:**** Reed–Solomon codes work on data blocks made of symbols, where each symbol contains multiple bits. Extra parity symbols are added to the block for error correction.\n- ****Multiple error correction:**** The number of errors that can be corrected depends on the extra symbols added. If 2t redundant symbols are used, the code can correct up to t corrupted symbols in a block.\n- ****Stronger than bit-level codes:**** Since errors are corrected at the symbol level, Reed–Solomon is more powerful than simple methods that correct only single-bit errors.\n- ****Very effective for burst errors:**** Burst errors usually damage several consecutive bits, often affecting full symbols. Reed–Solomon codes are designed to recover such damaged symbols accurately.\n- ****Wide practical usage:**** These codes are widely used in CDs, DVDs, Blu-ray discs, QR codes, barcodes, satellite communication, and digital TV, where data accuracy is critical.\n- ****Higher computation cost:**** Reed–Solomon codes need more complex encoding and decoding compared to simpler techniques like Hamming Code, but this complexity provides better error correction strength.\n## Types of Backward Error Correction\n### Stop-and-Wait ARQ\n- Stop-and-Wait ARQ is a basic Backward Error Correction method for reliable data transmission.\n- The sender transmits one frame at a time and waits for an acknowledgment (ACK) from the receiver.\n- The receiver sends an ACK only if the frame is received correctly, ensuring reliable delivery.\n- If a frame is lost, contains errors, or the ACK is not received, the sender retransmits the same frame.\n- A timer is used for each frame; if it expires before receiving an ACK, the frame is resent.\n- This method is simple and reliable, but inefficient for high-speed or long-delay networks due to idle waiting time.\n### Go-Back-N ARQ\n- Go-Back-N ARQ is a Backward Error Correction method that allows the sender to transmit multiple frames consecutively without waiting for individual acknowledgments.\n- It uses a sliding window at the sender to control how many frames can be sent before receiving ACKs.\n- The receiver accepts frames only in order; out-of-order frames are discarded even if they are correct.\n- The receiver sends cumulative acknowledgments indicating the highest in-order frame received successfully.\n- If a frame is lost or corrupted, the sender retransmits that frame and all subsequent frames in the window.\n- Go-Back-N improves throughput over Stop-and-Wait but can waste bandwidth if errors occur frequently.\n## Applications of Error Correction\n### ****Wireless and Mobile Communication (4G\/5G, Wi-Fi):****\n- Error correction ensures reliable data transmission over wireless channels, which are prone to interference, fading, and noise.\n- Techniques like Convolutional Codes, Turbo Codes, and LDPC codes are commonly used in 4G\/5G networks and Wi-Fi to improve throughput and reduce packet loss.\n### ****Satellite and Deep-Space Communication:****\n- Communication over long distances, such as satellite links or deep-space probes, experiences significant signal attenuation and delays.\n- Forward Error Correction methods like Reed–Solomon and Convolutional Codes allow receivers to correct errors without relying on retransmissions, which are impractical due to high latency.\n### ****Data Storage Devices (HDD, SSD, CDs, DVDs):****\n- Error correction ensures the integrity of stored data, compensating for physical defects, scratches, or degradation over time.\n- Codes such as Hamming Code, Reed–Solomon, and BCH codes are embedded in storage devices to detect and correct errors automatically.\n### ****QR Codes, Barcodes, and Digital Broadcasting:****\n- QR codes and barcodes use error correction (typically Reed–Solomon) to recover data if part of the code is damaged or obscured.\n- Digital TV, radio, and streaming services implement FEC techniques to maintain high-quality transmission even in noisy environments.","meta_canonical":null}

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Boilerpipe Text	Last Updated : 9 Jan, 2026 Error correction is the process of detecting and fixing errors that occur during data transmission so that the receiver can correctly understand the received data. Errors may happen due to noise, interference, or other transmission issues. Error correction techniques help maintain data integrity and ensure reliable communication between network devices. These techniques allow the system to recover correct information even when some transmitted bits are corrupted. Forward Error Correction (FEC): Forward Error Correction is an error control technique used during data transmission. The sender adds extra (redundant) bits to the original data before sending it. These extra bits help the receiver detect and correct errors on its own. The receiver does not need to request retransmission from the sender. This reduces delay and improves communication reliability. FEC is useful where retransmission is costly or not possible. It is commonly used in wireless networks, satellite communication, and multimedia streaming. Hamming Code is a simple and common example of a Forward Error Correction technique. Backward Error Correction: Backward Error Correction is an error control technique used in data communication. The receiver checks the received data for errors using error detection methods. If an error is found, the receiver sends a retransmission request to the sender. The sender retransmits the corrupted data until it is received correctly. This method requires a feedback channel between the sender and receiver. It provides reliable data delivery but can increase transmission delay. Backward Error Correction is commonly implemented using Automatic Repeat Request (ARQ) techniques. Common ARQ methods include Stop-and-Wait, Go-Back-N, and Selective Repeat. Types of Forward Error Correction (FEC) Hamming Code Hamming Code is a Forward Error Correction (FEC) technique used to make data transmission more reliable. It allows the receiver to detect and correct errors on its own without asking the sender to resend the data. Hamming Code can correct one-bit errors and detect two-bit errors, but it cannot fix two errors at the same time. It is suitable for systems where errors are rare and usually occur one bit at a time.2. Reed–Solomon Code Parity bits are placed at positions 1, 2, 4, 8, 16, …, which are powers of two. Each parity bit checks a specific group of data bits, helping locate the exact position of an error. The receiver uses parity checks (syndrome) to identify the incorrect bit and correct it if needed. Since the receiver can fix the error by itself, no retransmission is required, making it a true Forward Error Correction technique. Reed–Solomon Code Reed–Solomon Code is a block-based Forward Error Correction (FEC) technique widely used in digital communication and data storage systems. It works on symbols instead of individual bits, where each symbol contains multiple bits. Because of this symbol-based approach, Reed–Solomon codes are very effective at correcting burst errors, in which many consecutive bits are damaged during transmission or storage. Symbol-based working: Reed–Solomon codes work on data blocks made of symbols, where each symbol contains multiple bits. Extra parity symbols are added to the block for error correction. Multiple error correction: The number of errors that can be corrected depends on the extra symbols added. If 2t redundant symbols are used, the code can correct up to t corrupted symbols in a block. Stronger than bit-level codes: Since errors are corrected at the symbol level, Reed–Solomon is more powerful than simple methods that correct only single-bit errors. Very effective for burst errors: Burst errors usually damage several consecutive bits, often affecting full symbols. Reed–Solomon codes are designed to recover such damaged symbols accurately. Wide practical usage: These codes are widely used in CDs, DVDs, Blu-ray discs, QR codes, barcodes, satellite communication, and digital TV, where data accuracy is critical. Higher computation cost: Reed–Solomon codes need more complex encoding and decoding compared to simpler techniques like Hamming Code, but this complexity provides better error correction strength. Types of Backward Error Correction Stop-and-Wait ARQ Stop-and-Wait ARQ is a basic Backward Error Correction method for reliable data transmission. The sender transmits one frame at a time and waits for an acknowledgment (ACK) from the receiver. The receiver sends an ACK only if the frame is received correctly, ensuring reliable delivery. If a frame is lost, contains errors, or the ACK is not received, the sender retransmits the same frame. A timer is used for each frame; if it expires before receiving an ACK, the frame is resent. This method is simple and reliable, but inefficient for high-speed or long-delay networks due to idle waiting time. Go-Back-N ARQ Go-Back-N ARQ is a Backward Error Correction method that allows the sender to transmit multiple frames consecutively without waiting for individual acknowledgments. It uses a sliding window at the sender to control how many frames can be sent before receiving ACKs. The receiver accepts frames only in order; out-of-order frames are discarded even if they are correct. The receiver sends cumulative acknowledgments indicating the highest in-order frame received successfully. If a frame is lost or corrupted, the sender retransmits that frame and all subsequent frames in the window. Go-Back-N improves throughput over Stop-and-Wait but can waste bandwidth if errors occur frequently. Applications of Error Correction Wireless and Mobile Communication (4G/5G, Wi-Fi): Error correction ensures reliable data transmission over wireless channels, which are prone to interference, fading, and noise. Techniques like Convolutional Codes, Turbo Codes, and LDPC codes are commonly used in 4G/5G networks and Wi-Fi to improve throughput and reduce packet loss. Satellite and Deep-Space Communication: Communication over long distances, such as satellite links or deep-space probes, experiences significant signal attenuation and delays. Forward Error Correction methods like Reed–Solomon and Convolutional Codes allow receivers to correct errors without relying on retransmissions, which are impractical due to high latency. Data Storage Devices (HDD, SSD, CDs, DVDs): Error correction ensures the integrity of stored data, compensating for physical defects, scratches, or degradation over time. Codes such as Hamming Code, Reed–Solomon, and BCH codes are embedded in storage devices to detect and correct errors automatically. QR Codes, Barcodes, and Digital Broadcasting: QR codes and barcodes use error correction (typically Reed–Solomon) to recover data if part of the code is damaged or obscured. Digital TV, radio, and streaming services implement FEC techniques to maintain high-quality transmission even in noisy environments.
Markdown	[![geeksforgeeks](https://media.geeksforgeeks.org/gfg-gg-logo.svg)](https://www.geeksforgeeks.org/) ![search icon](https://media.geeksforgeeks.org/auth-dashboard-uploads/Property=Light---Default.svg) - Sign In - [Courses]() - [Tutorials]() - [Interview Prep]() - [CN Tutorial](https://www.geeksforgeeks.org/computer-networks/computer-network-tutorials/) - [Interview Questions](https://www.geeksforgeeks.org/computer-networks/commonly-asked-computer-networks-interview-questions-set-1/) - [Quizzes](https://www.geeksforgeeks.org/quizzes/50-computer-networks-mcqs-with-answers/) - [Gate](https://www.geeksforgeeks.org/computer-networks/computer-networks-for-gate/) - [OSI Model](https://www.geeksforgeeks.org/computer-networks/open-systems-interconnection-model-osi/) - [TCP-IP](https://www.geeksforgeeks.org/computer-networks/tcp-ip-model/) - [Network Security](https://www.geeksforgeeks.org/computer-networks/network-security/) - [COA](https://www.geeksforgeeks.org/computer-organization-architecture/computer-organization-and-architecture-tutorials) - [TOC](https://ww\)w.geeksforgeeks.org/theory-of-computation/introduction-of-theory-of-computation/) - [Compiler Design](https://www.geeksforgeeks.org/compiler-design/compiler-design-tutorials/) # Error Correction in Computer Networks Last Updated : 9 Jan, 2026 Error correction is the process of detecting and fixing errors that occur during data transmission so that the receiver can correctly understand the received data. Errors may happen due to noise, interference, or other transmission issues. Error correction techniques help maintain data integrity and ensure reliable communication between network devices. These techniques allow the system to recover correct information even when some transmitted bits are corrupted. ### Forward Error Correction (FEC): - Forward Error Correction is an error control technique used during data transmission. - The sender adds extra (redundant) bits to the original data before sending it. - These extra bits help the receiver detect and correct errors on its own. - The receiver does not need to request retransmission from the sender. - This reduces delay and improves communication reliability. - FEC is useful where retransmission is costly or not possible. - It is commonly used in wireless networks, satellite communication, and multimedia streaming. - Hamming Code is a simple and common example of a Forward Error Correction technique. ### Backward Error Correction: - Backward Error Correction is an error control technique used in data communication. - The receiver checks the received data for errors using error detection methods. - If an error is found, the receiver sends a retransmission request to the sender. - The sender retransmits the corrupted data until it is received correctly. - This method requires a feedback channel between the sender and receiver. - It provides reliable data delivery but can increase transmission delay. - Backward Error Correction is commonly implemented using Automatic Repeat Request (ARQ) techniques. - Common ARQ methods include Stop-and-Wait, Go-Back-N, and Selective Repeat. ## Types of Forward Error Correction (FEC) ### Hamming Code Hamming Code is a Forward Error Correction (FEC) technique used to make data transmission more reliable. It allows the receiver to detect and correct errors on its own without asking the sender to resend the data. - Hamming Code can correct one-bit errors and detect two-bit errors, but it cannot fix two errors at the same time. - It is suitable for systems where errors are rare and usually occur one bit at a time.2. Reed–Solomon Code - Parity bits are placed at positions 1, 2, 4, 8, 16, …, which are powers of two. - Each parity bit checks a specific group of data bits, helping locate the exact position of an error. - The receiver uses parity checks (syndrome) to identify the incorrect bit and correct it if needed. - Since the receiver can fix the error by itself, no retransmission is required, making it a true Forward Error Correction technique. ### Reed–Solomon Code Reed–Solomon Code is a block-based Forward Error Correction (FEC) technique widely used in digital communication and data storage systems. It works on symbols instead of individual bits, where each symbol contains multiple bits. Because of this symbol-based approach, Reed–Solomon codes are very effective at correcting burst errors, in which many consecutive bits are damaged during transmission or storage. - **Symbol-based working: Reed–Solomon codes work on data blocks made of symbols, where each symbol contains multiple bits. Extra parity symbols are added to the block for error correction. - Multiple error correction: The number of errors that can be corrected depends on the extra symbols added. If 2t redundant symbols are used, the code can correct up to t corrupted symbols in a block. - Stronger than bit-level codes: Since errors are corrected at the symbol level, Reed–Solomon is more powerful than simple methods that correct only single-bit errors. - Very effective for burst errors: Burst errors usually damage several consecutive bits, often affecting full symbols. Reed–Solomon codes are designed to recover such damaged symbols accurately. - Wide practical usage: These codes are widely used in CDs, DVDs, Blu-ray discs, QR codes, barcodes, satellite communication, and digital TV, where data accuracy is critical. - Higher computation cost: Reed–Solomon codes need more complex encoding and decoding compared to simpler techniques like Hamming Code, but this complexity provides better error correction strength. ## Types of Backward Error Correction ### Stop-and-Wait ARQ - Stop-and-Wait ARQ is a basic Backward Error Correction method for reliable data transmission. - The sender transmits one frame at a time and waits for an acknowledgment (ACK) from the receiver. - The receiver sends an ACK only if the frame is received correctly, ensuring reliable delivery. - If a frame is lost, contains errors, or the ACK is not received, the sender retransmits the same frame. - A timer is used for each frame; if it expires before receiving an ACK, the frame is resent. - This method is simple and reliable, but inefficient for high-speed or long-delay networks due to idle waiting time. ### Go-Back-N ARQ - Go-Back-N ARQ is a Backward Error Correction method that allows the sender to transmit multiple frames consecutively without waiting for individual acknowledgments. - It uses a sliding window at the sender to control how many frames can be sent before receiving ACKs. - The receiver accepts frames only in order; out-of-order frames are discarded even if they are correct. - The receiver sends cumulative acknowledgments indicating the highest in-order frame received successfully. - If a frame is lost or corrupted, the sender retransmits that frame and all subsequent frames in the window. - Go-Back-N improves throughput over Stop-and-Wait but can waste bandwidth if errors occur frequently. ## Applications of Error Correction ### Wireless and Mobile Communication (4G/5G, Wi-Fi): - Error correction ensures reliable data transmission over wireless channels, which are prone to interference, fading, and noise. - Techniques like Convolutional Codes, Turbo Codes, and LDPC codes are commonly used in 4G/5G networks and Wi-Fi to improve throughput and reduce packet loss. ### Satellite and Deep-Space Communication: - Communication over long distances, such as satellite links or deep-space probes, experiences significant signal attenuation and delays. - Forward Error Correction methods like Reed–Solomon and Convolutional Codes allow receivers to correct errors without relying on retransmissions, which are impractical due to high latency. ### Data Storage Devices (HDD, SSD, CDs, DVDs): - Error correction ensures the integrity of stored data, compensating for physical defects, scratches, or degradation over time. - Codes such as Hamming Code, Reed–Solomon, and BCH codes are embedded in storage devices to detect and correct errors automatically. ### QR Codes, Barcodes, and Digital Broadcasting: - QR codes and barcodes use error correction (typically Reed–Solomon) to recover data if part of the code is damaged or obscured. - Digital TV, radio, and streaming services implement FEC techniques to maintain high-quality transmission even in noisy environments. Suggested Quiz ![reset](https://media.geeksforgeeks.org/auth-dashboard-uploads/Reset-icon---Light.svg) 4 Questions In Forward Error Correction (FEC), which of the following is TRUE? - A Errors are corrected by retransmissions from sender - B Receiver corrects errors without asking sender to resend - C Both sender and receiver retransmit corrupted data - D Errors cannot be corrected, only detected Backward Error Correction relies on: - A Receiver correcting the bit pattern directly - B Sender retransmitting when errors are detected - C No acknowledgment mechanism - D Receiver predicting missing bits In Hamming Code, redundant bits are placed at positions: - A Odd positions only - B Prime-number positions - C Positions that are powers of 2 - D Last positions of the message The number of redundant bits ‘r’ needed to protect ‘d’ data bits in Hamming Code satisfies: - A 2^r ≥ d + r + 1 - B 2r ≥ d - C r = log₂(d) - D 2^(d+r) ≥ r ![success](https://media.geeksforgeeks.org/auth-dashboard-uploads/sucess-img.png) Quiz Completed Successfully Your Score :0/4 Accuracy :0% Login to View Explanation 1**/4 \< Previous Next \> Comment [T](https://www.geeksforgeeks.org/user/tarakki100/) [tarakki100](https://www.geeksforgeeks.org/user/tarakki100/) 4 Article Tags: Article Tags: [Computer Networks](https://www.geeksforgeeks.org/category/computer-subject/computer-networks/) [Geeks Premier League](https://www.geeksforgeeks.org/category/geeksforgeeks-initiatives/geeks-premier-league/) [Geeks Premier League 2023](https://www.geeksforgeeks.org/tag/geeks-premier-league-2023/) ### Explore [![GeeksforGeeks](https://media.geeksforgeeks.org/auth-dashboard-uploads/gfgFooterLogo.png)](https://www.geeksforgeeks.org/) ![location](https://media.geeksforgeeks.org/img-practice/Location-1685004904.svg) Corporate & Communications Address: A-143, 7th Floor, Sovereign Corporate Tower, Sector- 136, Noida, Uttar Pradesh (201305) ![location](https://media.geeksforgeeks.org/img-practice/Location-1685004904.svg) Registered Address: K 061, Tower K, Gulshan Vivante Apartment, Sector 137, Noida, Gautam Buddh Nagar, Uttar Pradesh, 201305 [![GFG App on Play Store](https://media.geeksforgeeks.org/auth-dashboard-uploads/googleplay-%281%29.png)](https://geeksforgeeksapp.page.link/gfg-app)[![GFG App on App Store](https://media.geeksforgeeks.org/auth-dashboard-uploads/appstore-%281%29.png)](https://geeksforgeeksapp.page.link/gfg-app) - 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Readable Markdown	Last Updated : 9 Jan, 2026 Error correction is the process of detecting and fixing errors that occur during data transmission so that the receiver can correctly understand the received data. Errors may happen due to noise, interference, or other transmission issues. Error correction techniques help maintain data integrity and ensure reliable communication between network devices. These techniques allow the system to recover correct information even when some transmitted bits are corrupted. ### Forward Error Correction (FEC): - Forward Error Correction is an error control technique used during data transmission. - The sender adds extra (redundant) bits to the original data before sending it. - These extra bits help the receiver detect and correct errors on its own. - The receiver does not need to request retransmission from the sender. - This reduces delay and improves communication reliability. - FEC is useful where retransmission is costly or not possible. - It is commonly used in wireless networks, satellite communication, and multimedia streaming. - Hamming Code is a simple and common example of a Forward Error Correction technique. ### Backward Error Correction: - Backward Error Correction is an error control technique used in data communication. - The receiver checks the received data for errors using error detection methods. - If an error is found, the receiver sends a retransmission request to the sender. - The sender retransmits the corrupted data until it is received correctly. - This method requires a feedback channel between the sender and receiver. - It provides reliable data delivery but can increase transmission delay. - Backward Error Correction is commonly implemented using Automatic Repeat Request (ARQ) techniques. - Common ARQ methods include Stop-and-Wait, Go-Back-N, and Selective Repeat. ## Types of Forward Error Correction (FEC) ### Hamming Code Hamming Code is a Forward Error Correction (FEC) technique used to make data transmission more reliable. It allows the receiver to detect and correct errors on its own without asking the sender to resend the data. - Hamming Code can correct one-bit errors and detect two-bit errors, but it cannot fix two errors at the same time. - It is suitable for systems where errors are rare and usually occur one bit at a time.2. Reed–Solomon Code - Parity bits are placed at positions 1, 2, 4, 8, 16, …, which are powers of two. - Each parity bit checks a specific group of data bits, helping locate the exact position of an error. - The receiver uses parity checks (syndrome) to identify the incorrect bit and correct it if needed. - Since the receiver can fix the error by itself, no retransmission is required, making it a true Forward Error Correction technique. ### Reed–Solomon Code Reed–Solomon Code is a block-based Forward Error Correction (FEC) technique widely used in digital communication and data storage systems. It works on symbols instead of individual bits, where each symbol contains multiple bits. Because of this symbol-based approach, Reed–Solomon codes are very effective at correcting burst errors, in which many consecutive bits are damaged during transmission or storage. - **Symbol-based working: Reed–Solomon codes work on data blocks made of symbols, where each symbol contains multiple bits. Extra parity symbols are added to the block for error correction. - Multiple error correction: The number of errors that can be corrected depends on the extra symbols added. If 2t redundant symbols are used, the code can correct up to t corrupted symbols in a block. - Stronger than bit-level codes: Since errors are corrected at the symbol level, Reed–Solomon is more powerful than simple methods that correct only single-bit errors. - Very effective for burst errors: Burst errors usually damage several consecutive bits, often affecting full symbols. Reed–Solomon codes are designed to recover such damaged symbols accurately. - Wide practical usage: These codes are widely used in CDs, DVDs, Blu-ray discs, QR codes, barcodes, satellite communication, and digital TV, where data accuracy is critical. - Higher computation cost: Reed–Solomon codes need more complex encoding and decoding compared to simpler techniques like Hamming Code, but this complexity provides better error correction strength. ## Types of Backward Error Correction ### Stop-and-Wait ARQ - Stop-and-Wait ARQ is a basic Backward Error Correction method for reliable data transmission. - The sender transmits one frame at a time and waits for an acknowledgment (ACK) from the receiver. - The receiver sends an ACK only if the frame is received correctly, ensuring reliable delivery. - If a frame is lost, contains errors, or the ACK is not received, the sender retransmits the same frame. - A timer is used for each frame; if it expires before receiving an ACK, the frame is resent. - This method is simple and reliable, but inefficient for high-speed or long-delay networks due to idle waiting time. ### Go-Back-N ARQ - Go-Back-N ARQ is a Backward Error Correction method that allows the sender to transmit multiple frames consecutively without waiting for individual acknowledgments. - It uses a sliding window at the sender to control how many frames can be sent before receiving ACKs. - The receiver accepts frames only in order; out-of-order frames are discarded even if they are correct. - The receiver sends cumulative acknowledgments indicating the highest in-order frame received successfully. - If a frame is lost or corrupted, the sender retransmits that frame and all subsequent frames in the window. - Go-Back-N improves throughput over Stop-and-Wait but can waste bandwidth if errors occur frequently. ## Applications of Error Correction ### Wireless and Mobile Communication (4G/5G, Wi-Fi): - Error correction ensures reliable data transmission over wireless channels, which are prone to interference, fading, and noise. - Techniques like Convolutional Codes, Turbo Codes, and LDPC codes are commonly used in 4G/5G networks and Wi-Fi to improve throughput and reduce packet loss. ### Satellite and Deep-Space Communication: - Communication over long distances, such as satellite links or deep-space probes, experiences significant signal attenuation and delays. - Forward Error Correction methods like Reed–Solomon and Convolutional Codes allow receivers to correct errors without relying on retransmissions, which are impractical due to high latency. ### Data Storage Devices (HDD, SSD, CDs, DVDs): - Error correction ensures the integrity of stored data, compensating for physical defects, scratches, or degradation over time. - Codes such as Hamming Code, Reed–Solomon, and BCH codes are embedded in storage devices to detect and correct errors automatically. ### QR Codes, Barcodes, and Digital Broadcasting:** - QR codes and barcodes use error correction (typically Reed–Solomon) to recover data if part of the code is damaged or obscured. - Digital TV, radio, and streaming services implement FEC techniques to maintain high-quality transmission even in noisy environments.
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