MT92220 Zarlink Semiconductor, MT92220 Datasheet - Page 85

• Manufacturer Part Number: MT92220
• Description: 1023 Channel Voice Over IP/AAL2 Processor
• Manufacturer: Zarlink Semiconductor

Data Sheet
One of the most important characteristics of the generation of AAL2 packets is that it uses the bus timestamp to
synchronize and generate the sequence number within the UUI. This has many advantages, notably deterministic
behavior of the sequence numbers and the synchronization of different channels' sequence numbers together,
allowing completely synchronized transport of several voice channels across many AAL2 connections. The UUI
sequence number is extracted by dividing the current timestamp by the Sequence Number Interval, then
performing a modulo by the total sequence number sequence size. For example, if the Sequence Number Interval
is 40 frames and 4 sequence number bits are used, the operation is (timestamp / 40) % (2^4). These operation
must also take into account the fact that the timestamp can wrap: the Timestamp Remainder and Timestamp Wrap
Inc fields take care of that. Timestamp Wrap Inc must be programmed to: 2
(2
The format of the TX AAL2 connection structure is the following:
Num Seq Bits
).
+1A
+1C
+1E
+10
+14
+16
+18
+20
+24
+26
+12
+22
+A
+C
+E
+0
+2
+4
+6
+8
b15
b14
b13
Figure 47 - TX AAL2 Connection Structure
b12
TX AAL2 VC Structure Base Address [20:5]
b11
Transmitted Packet Count [15:0]
Transmitted Octet Count [31:16]
Transmitted Octet Count [15:0]
b10
Zarlink Semiconductor Inc.
b9
b8
b7
b6
b5
AAL2 CID [7:0]
b4
32
b3
% ((Sequence Number Interval *
b2
b1
b0
MT92220
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