---
title: "Dataword vs codeword; error coding techniques"
subject: "Data Communication"
chapter: 8
key: "semester_5/data_communication:dataword-codeword-error-coding"
source: https://www.bctengineer.com/q/semester_5/data_communication/dataword-codeword-error-coding
site: BCT Engineering
---

# Dataword vs codeword; error coding techniques

Data Communication · Chapter 8: Information Theory and Coding

- Asked in: 2071 Chaitra, 2+4 marks
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/data_communication/dataword-codeword-error-coding
- Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-8

## Question

Define Dataword and Codeword with suitable example. List the error detection and correction coding techniques with their application case.

## Short answer

A dataword is the k-bit original message; a codeword is the n-bit encoded block with n−k redundant bits, e.g., 1011 → 1011100 in (7,4) Hamming code. Key error techniques: parity (UART), checksum (IP), CRC (Ethernet), Hamming (ECC RAM), Reed-Solomon (CD/DVD), convolutional (GSM), Turbo/LDPC (4G/5G).

## Answer

#### Dataword and codeword
- **Dataword:** the original block of k message bits before encoding.
- **Codeword:** the n-bit block (n > k) produced by the encoder, containing the dataword plus n − k redundant bits.

Example: in a (7,4) Hamming code, the dataword 1011 becomes the codeword 1011100. In a simple even-parity code, dataword 1011 becomes codeword 10111 (parity bit 1).

#### Error detection and correction techniques and applications
| Technique | Capability | Application |
|---|---|---|
| Parity check (simple, 2D) | Detects odd errors (2D can correct one) | UART serial links, memory |
| Checksum | Detects errors | IP, TCP, UDP headers |
| CRC | Detects burst errors | Ethernet, HDLC, USB, Wi-Fi |
| Hamming code | Corrects 1 bit | ECC memory (RAM) |
| Reed-Solomon | Corrects burst errors | CD/DVD, QR codes, satellite |
| Convolutional code (Viterbi) | Corrects random errors | GSM, deep-space, Wi-Fi |
| Turbo / LDPC | Near Shannon limit | 3G/4G/5G, DVB-S2 |
| ARQ (retransmission) | Detect + resend | TCP, data link layer |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which is correct?
   A. Dataword has n bits and codeword has k bits
   B. Dataword is the k-bit original block; codeword is the n-bit encoded block with redundancy (n > k)
   C. Both have the same length
   D. Codeword is the message before encoding
   Answer: B. The encoder turns a k-bit dataword into an n-bit codeword by adding n - k redundant bits. (Key point: Dataword vs codeword)

2. In an even-parity code, what is the codeword for dataword 1011?
   A. 10110
   B. 10111
   C. 01011
   D. 1011100
   Answer: B. 1011 has three 1s, so the parity bit is 1 to make the count even, giving 10111. (Key point: Even parity example)

3. Which technique is matched with its application correctly?
   A. CRC with Ethernet frames
   B. Hamming code with CD/DVD scratches
   C. Reed-Solomon with simple UART parity
   D. Checksum with ECC memory
   Answer: A. CRC detects burst errors and is used in Ethernet, HDLC and USB; Hamming is for ECC memory and Reed-Solomon for CD/DVD. (Key point: Technique and application)

## Related in Data Communication

- [Forward error correction using Hamming code](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Afec-hamming) — Data Communication, chapter 8
- [CRC error detection with example](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Acrc-explain) — Data Communication, chapter 8, asked 5×
- [List digital-to-digital line coding techniques](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aline-coding-techniques-list) — Data Communication, chapter 5
- [Checksum error detection](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Achecksum-12-15-15-10-5-2) — Data Communication, chapter 8
- [Linear block coding with example](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Alinear-block-code-explain) — Data Communication, chapter 8, asked 3×
- [Source coding vs channel coding](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Asource-vs-channel-coding) — Data Communication, chapter 8

## Related in other subjects

- [Error detection vs correction; rate ½ convolutional encoder](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aerror-detect-correct-conv-half-rate) — Communication Systems, chapter 8
- [Short note: Error detection and correction capability](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Ashort-note-error-detect-correct-capability) — Communication Systems, chapter 8
- [Error correction vs detection, bit stuffing](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Aerror-correct-detect-bitstuff) — Computer Networks and Security, chapter 3
- [Error detection in serial data transmission](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aserial-error-detection) — Instrumentation II, chapter 3, asked 2×