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Logical
Combination of SDM Channels Achieves Gigabit Rates
For Far Less Cost and RF Bandwidth Compared to QAM
Comparative Costs to Achieve a 1Gbps Logical Channel
Summarizing on the comparative costs of SDM vs. QAM logical channels, it would be useful to observe what the comparative costs would be to achieve a 1Gbps logical channel. The following table summarizes combining 6SDM channels and 256QAM, and 1024QAM logical channels with based on the information presented in the previous section.
| Modulation / MHz | 1024QAM |
256QAM |
6SDM |
| Relative QAM cost to SDM cost |
4.2 |
3.2 |
1 |
| Relative
QAM RF Bandwidth to SDM RF Bandwidth |
1.6 |
1.9 |
1 |
| Gbps | 1.062 |
1.027 |
0.961 |
Sizing towards 1Gbps logical channels, based on the above table and figure:
- In 90MHz of spectrum, with SDM 18Mhz channels, 5 * 192.2 Mbps = 961Mbps at a cost of 5x, neglecting the cost of inverse multiplexing additions and economy of scale reductions.
- In 168MHz, with QAM 24MHz (256QAM/8+8+8 configuration), 7 * 153.0 Mbps = 1027Mbps at a cost of 16x, neglecting the cost of inverse multiplexing changes and economy of scale reductions
- In 144MHz, with QAM 1024MHz (1024QAM/6+6+6 configuration), 8*132.8 Mbps = 1062Mbps at a cost of 21x, neglecting the cost of inverse multiplexing changes and economy of scale reductions
As shown in the above list, SDM achieves near 1Gbps logical capacity using far less RF bandwidth than QAM and at a significantly lower cost than logical QAM channels.
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