12 Data Rate Calculations
192
2. The tables in Section 12.3 contain data rates for links of zero range. Use the curves
in Section 12.4 to look up the Throughput Factor that must be applied to adjust the
data rates for the actual range of the link.
3. Multiply the data rates by the Throughput Factor to give the throughput capacity of
the link.
NOTE
There is a small difference between the rates for IP and TDM because there is
fragmentation in TDM (for low priority traffic) which causes the throughput to be
reduced buy approximately 1% compared to the IP mode.
12.2.2 Example
Suppose that the link characteristics are:
•
Link Symmetry = 1:1
•
Link Mode Optimization = TDM
•
Modulation Mode = 64QAM 0.83 Dual
•
Channel Bandwidth = 10 MHz
•
Link Range = 55 km
Applying the calculation procedure:
1. Use
Table 21 to look up the data throughput capacity rates (Mbit/s):
Tx = 12.29
Rx = 12.29
Both = 24.59
(assuming that Line Of Sight mode is disabled)
2. Use
Figure 121 to look up the Throughput Factor for 1:1, TDM and Link Range 55
km. The factor is 0.7.
3. Multiply the rates from Step 2 by the Throughput Factor from Step 3 to give the
throughput capacity of the link (Mbit/s):
Tx = 8.60
Rx = 8.60
Both = 17.21
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