AAL 1 operation

User info (e.g. PCM speech)

47 bytes (or less)

SAR-PDU

ATM cell

H

Payload

1

3

3

1

•  CSI bit (can be used for transmitting timing information) •  Sequence number (modulo 8) •  CRC field (CRC check for first seven bits) •  Parity bit (parity check for SAR-PDU header only)