PXB4221EV34NP Infineon Technologies, PXB4221EV34NP Datasheet - Page 275

• Manufacturer Part Number: PXB4221EV34NP
• Manufacturer: Infineon Technologies

Specifications of PXB4221EV34NP

• Data Rate: 2.048Mbps
• Number Of Channels: 1
• Operating Supply Voltage (typ): 3.3V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Not Compliant

Robust Sequence Count Algorithm
This algorithm is completely described in annex D of the ETSI B-ISDN AAL type 1
Specification [17] and ITU-T I.363.1 [31] and is shown in Figure
The algorithm is described by a state machine of 5 states. A change in states within the
state machine is indicated by an arrow, on which there are two distinct values
represented. The first value refers to the event that originates the state change, and the
second value refers to the action to be taken as a result of that event.
A decision in this algorithm is taken after evaluation of 2 consecutive SN. This means
that when a cell is received it must be temporarily stored, waiting for the next cell before
it is finally passed to the reassembly buffer. In the state machine, an action to be taken
(accept or discard) always refers to the stored cell.
The sequence counting of modulo 8 permits that the algorithm detects a maximum of to
6 consecutive lost cells and 1 misinserted cell, assuming that misinsertion of one cell is
at least as probable as the loss of 7 consecutive cells.
Lost cells are compensated by inserting an appropriate number of dummy cells into the
transmitted data of the channel. This is required to maintain bit count integrity. The
number of octets inserted per dummy cell is equal to the number of user information
octets in the SAR-PDU payload of each cell.
When one misinserted cell is detected, the algorithm is able to delete the misinserted
cell, because of the delay of one cell in taking a decision.
Data Sheet
275
PXB 4219E, PXB 4220E, PXB 4221E
Figure
75.
IWE8, V3.4
Appendix
2003-01-20