User's Manual

W-CMTS
Upconverter freq-A
Upconverter freq-B
2-way splitter
Trans/Ant 1
Trans/Ant 3
2-way splitter
Trans/Ant 2
Trans/Ant 4
Downstream 2
10 Mbps
Downstream 1
10 Mbps
Figure 4-4: Four-sector ABAB system with dual downstream data stream, total 20 Mbps.
4.3 Frequency Planning – Upstream
This Section discusses several issues related to planning the use of the frequency band for
Upstream communications.
4.3.1 Upstream Logical Channels
It is important to recall that any given downstream logical channel may have a large number of
upstream logical channels associated with it, and that any given upstream is always associated
with one and only one downstream. Thus, for example, the system in Figure 4-3 has only one
logical downstream (split to all sectors) and four logical upstreams (one from each sector)
connected to 4 upstream input ports on the W-CMTS. The association of one or more upstream
logical channel with a downstream logical channel is made in the W-CMTS configuration.
Upstream logical channels from one or more Hub Transceivers may not
be combined into a
single upstream input to the W-CMTS.
4.3.2 Upstream Frequencies
Figure 4-5, below, illustrates the 4 upstream signals from 4 Hub Transceivers arranged in a
standard omnidirectional receive configuration. Note that this upstream configuration applies to
all of the downstream configurations illustrated in the Figures above.
June 2003 Page 4-6