Correct transmission errors of the radio channel

The main techniques used to correct transmission errors in radio channels:

Forward Error Correction (FEC):

Adds redundant data (parity bits) to the transmitted message that allows the receiver to detect and correct errors without requesting retransmission
Common FEC codes include:
- Convolutional codes: Continuous encoding of bit streams, good for random errors
- Reed-Solomon codes: Block-based coding excellent for burst errors
- Turbo codes and LDPC: Modern, powerful codes approaching Shannon limit
- Hamming codes: Simple codes that can correct single-bit errors

Automatic Repeat Request (ARQ/ACK):

Receiver checks message integrity using error detection codes (like CRC)
If errors are detected, receiver requests retransmission via negative acknowledgment (NACK)
On successful receipt, sends positive acknowledgment (ACK)
Three main ARQ types:
- Stop-and-wait: Simplest form, waits for ACK before sending next packet
- Go-back-N: Sends multiple packets, retransmits all from error point
- Selective repeat: Only retransmits specific corrupted packets

Interleaving:

Rearranges data bits/symbols before transmission
Spreads burst errors across multiple code words, making them easier to correct
Common types:
- Block interleaving: Writes data in rows, transmits in columns
- Convolutional interleaving: Continuous process using shift registers
- Helical interleaving: Variation optimized for specific applications

These techniques are often used in combination:

The choice of specific techniques depends on:

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