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A CRC has properties that make it well suited for detecting burst errors. CRCs are particularly easy to implement in hardware and are therefore commonly used in computer networks and storage devices such as hard disk drives. The parity bit can be seen as a special-case 1-bit CRC.
as a result, even if the CRC is encrypted with a stream cipher that uses XOR as its combining operation (or mode of block cipher which effectively turns it into a stream cipher, such as OFB or CFB), both the message and the associated CRC can be manipulated without knowledge of the encryption key; this was one of the well-known design flaws of ...
One of the most commonly encountered CRC polynomials is known as CRC-32, used by (among others) Ethernet, FDDI, ZIP and other archive formats, and PNG image format. Its polynomial can be written msbit-first as 0x04C11DB7, or lsbit-first as 0xEDB88320.
These inversions are extremely common but not universally performed, even in the case of the CRC-32 or CRC-16-CCITT polynomials. They are almost always included when sending variable-length messages, but often omitted when communicating fixed-length messages, as the problem of added zero bits is less likely to arise.
Interleaving alleviates this problem by shuffling source symbols across several code words, thereby creating a more uniform distribution of errors. [21] Therefore, interleaving is widely used for burst error-correction. The analysis of modern iterated codes, like turbo codes and LDPC codes, typically assumes an independent distribution of ...
It is also used in Evolution-Data Optimized and LTE wireless networks. Type I Hybrid ARQ is used in ITU-T G.hn , a high-speed Local area network standard that can operate at data rates up to 1 Gbit/s over existing home wiring ( power lines , phone lines and coaxial cables ).
In computer networking, an Ethernet frame is a data link layer protocol data unit and uses the underlying Ethernet physical layer transport mechanisms. In other words, a data unit on an Ethernet link transports an Ethernet frame as its payload.
To convolutionally encode data, start with k memory registers, each holding one input bit.Unless otherwise specified, all memory registers start with a value of 0. The encoder has n modulo-2 adders (a modulo 2 adder can be implemented with a single Boolean XOR gate, where the logic is: 0+0 = 0, 0+1 = 1, 1+0 = 1, 1+1 = 0), and n generator polynomials — one for each adder (see figure below).