Data Specifications - Cisco uBR900 Series Configuring

Feature Overview
Note
high upstream data throughput is not demanded since the volume of data transmitted upstream is
typically small.

Data Specifications

Table 1
Description
Frequency Range
Modulation
Data Rate
Bandwidth
FEC
One Channel
Signal-to-Noise Ratio
(SNR)
6 Cisco IOS Release 12.0(7)T
Interactive games are the exception. Although low latency is required in gaming applications,
Cisco uBR900 Series Cable Access Router Data Specifications
Downstream Values
88 to 860 MHz
64 QAM
256 QAM
30 Mbps/64 QAM
(27 Mbit/sec after FEC overhead)
42.8 Mbps/256 QAM
(36 Mbit/sec after FEC overhead)
6 MHz
RS (122, 128) Trellis
Receive level of digital signal
-15 to +15 dBmV
Most field measurements are of nearby
Note
or adjacent analog signal which is normally
+6 to +10 dB (system specific) above the
digital signal level
64 QAM:
>23.5 dB @ BER<10^8
256 QAM*:
>30 dB @ BER <10^-8
(For input level between +15 and -8 dBmV,
SNR must be greater than 30 dB. For input
level between -8 and -15 dBmV, SNR must be
greater than 33 dB.)
These performance numbers are in
Note
laboratory-controlled conditions against
statistically pure noise sources (AWGN). Since
such conditions do not exist in practise, a 6 dB
or more SNR margin is required for reliable
operation. Check with your local system
guidelines.
Upstream Values
5 to 42 MHz
QPSK
16 QAM
QPSK—320 Kbit/sec to 5 Mbit/sec
16 QAM—640 Kbit/sec to 10 Mbit/sec
200K, 400K, 800K, 1.6M,
3.2 MHz
Reed Solomon
QPSK— +8 to +58 dBmV
16 QAM— +8 to +55 dBmV
QPSK:
>15 dB @ BER<10^-8
(QPSK will work at 98% successful
ping rate for SNR>13 dB. A SNR of
15 dB will be needed to get almost
optimal packets per minute transition.)
16 QAM:
>22 dB @ BER <10^-8
(For 16 QAM, a SNR>22 dB makes the
grade for 98% ping efficiency. To get
good packet rate, you need
SNR>25 dB)
These measurements were made
Note
for 0 and -10 dBmV input to the CMTS,
1280 ksym/sec and 64 bytes packet size
with a Cisco uBR904 cable access router
and laboratory-controlled conditions.