cx28365 Mindspeed Technologies, cx28365 Datasheet - Page 92

• Manufacturer Part Number: cx28365
• Description: X12, X6, X4 T3/e3 Framer And Atm Cell Transmission Convergence Sublayer Processor
• Manufacturer: Mindspeed Technologies

Functional Description
2.2.7
2.2.7.1
2-54
Cell Scrambler
Table 2-10. Cell Screening—Matching
Table 2-11. Cell Screening—Accept/Reject Cell
The ATM standard requires cell scrambling to ensure that only valid headers are found
in the cell delineation process. Scrambling randomizes any repeated patterns or other
data strings that could be mistaken for valid headers. The Cell Processor supports Self
Synchronizing Scrambler (SSS) as defined by ITU-T I.432:
SSS Scrambling
SSS scrambling uses the polynomial X
header bytes untouched. It can be enabled in EnTxCellScr, bit 5, of the CGEN register
(0x08).
Descrambling uses the same polynomial to recover the 48-byte cell payload. It can be
enabled in EnRxCellScr, bit 4, of the CVAL register (0x0C). SSS scrambling runs at
up to 45 Mbps.
Receive Cell Mask Bit
Preliminary Information/Mindspeed Proprietary and Confidential
0
0
0
0
1
Match
Match
Cell
Mindspeed Technologies™
Fail
Fail
Receive Cell Header Bit
Reject Header
0
0
1
1
x
43
+ 1 to scramble the payload, leaving the five
0
1
0
1
Incoming Bit
0
1
0
1
x
Accept Cell
Accept Cell
Reject Cell
Reject Cell
CX28365/6/4 Data Sheet
Result
Result
Match
Match
Match
Fail
Fail
500028C