Atm Aggregation - Ericsson MINI-LINK TN R4 ETSI Technical Description

3.8

ATM Aggregation

3.8.1 Overview
The growing demand for higher transmission capacity in access networks can
be handled by increasing the physical capacity, introducing traffic aggregation
or combining the two approaches.
ATM traffic aggregation in MINI-LINK is achieved by fitting an ATM Aggregation
Unit (AAU) in the subrack. This is typically done at hub sites where HSPA traffic
is aggregated, thus reducing the number of required E1 links in the northbound
direction. The AAU performs ATM VP/VC cross-connection providing statistical
gains.
Figure 36 on page 43 shows an example of how Virtual Paths (VP) and Virtual
Channels (VC), carried over E1s, can be cross-connected reducing the number
of required E1s.
Figure 36
Often the transmission network is used for both GSM and WCDMA traffic. The
GSM traffic is handled as ordinary TDM traffic routed in the backplane and
transported transparently through the NE while WCDMA traffic is routed to the
AAU for packet aggregation before it is routed to its destination port. WCDMA
traffic comprises both R99 standard (voice and data channel up to 384 kbit/s)
and HSDPA traffic. The largest aggregation gain is however obtained for the
HSDPA traffic, when the low priority traffic can be transported using best effort
service categories.
Figure 37 on page 44 shows how the different traffic types are routed in the
backplane.
12/221 02-CSH 109 32/1-V1 Uen A 2008-03-14
VC/UBR+
11.3 Mbit/s
VP/CBR 8xE1
VC/CBR
4.7 Mbit/s
VC/UBR+
11.7 Mbit/s
VP/CBR 8xE1
VC/CBR
4.3 Mbit/s
VP/VC cross-connection
MINI-LINK TN
with AAU
11xE1
Basic Node
VC/UBR+
Shared
13 Mbit/s
VC/UBR+
VP/CBR
VC/CBR
4.7 Mbit/s
VC/CBR
4.3 Mbit/s
8924
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