Motorola BSR 2000, Configuration And Management Manual

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Release 1.0 Configuring the CMTS
526360-001-00 Rev. B MGBI 6-21
DOCSIS 2.0 Only Channel Types
The DOCSIS 2.0 only channel types, A-TDMA and S-CDMA, greatly enhance
upstream channel capacity, as shown in
Table 6-2 :
Other Channel Types
To accommodate DOCSIS 1.0 and 1.1 cable modems in a DOCSIS 2.0 environment,
DOCSIS 2.0 also supports, in addition to A-TDMA and S-CDMA, two other logical
channel types:
■
TDMA (Time Division Multiple Access)
■
MTDMA (Mixed TDMA and A-TDMA)
Logical Channel Operation
For more than one logical channel to co-exist on the same physical CMTS port and
use the single frequency configured for that port, each logical channel type is
assigned a unique set of non-overlapping timeslots in which to communicate.
For example, the bandwidth scheduler that resides in the CMTS module allocates
S-CDMA bursts to S-CDMA timeslots, while allocating DOCSIS 1.
x
or A-TDMA
bursts to TDMA timeslots.
Table 6-2 Features of DOCSIS 2.0 Logical Channel Types
DOCSIS 2.0 Channel Type Features
A-TDMA A-TDMA features include:
• Increased pre-equalization and equalization from 8 to 24 taps
• Increased Forward Error Correction capabilities from 10 to 16
bytes.
• Increased channel width from 3.2 to 6.4 MHz
• Expanded upstream channel bandwidth capacity from 10Mb to
30Mb
• Increased modulation orders (QPSK, 8,16,32,64 QAM)
• Byte interleaving
S-CDMA S-CDMA supports all the features of A-TDMA with the addition of:
• CDMA spreading
• Trellis Coded Modulation (TCM)
• 128 QAM with TCM
• 128 codes