RF Spectrum Transitions

Existing Sytems

The North American cable plan allows for 5-42MHz for upstream communications and from 52MHz and above for downstream communications. The upgrade to a Hybrid Fiber-Coaxial cable plants provided an initial downstream passband expansion to 750MHz, and later systems and deployments improved to 860MHz.

~20Mbps upstream, ~500Mbps downstream in this example

From 52MHz to 500MHz the spectrum is dedicated exclusively to analog NTSC TV channels. Approximately 78 to 80 channels are occupied in this space.

Above 550MHz, 6MHz channelization conventions are still followed, however the modulation is now digital, rather than analog. For QAM based digital communications, each 6MHz deployed only uses ~5MHz for modulation. The remaning 1MHz is needed for guardbands to avoid adjacent channel interference. This means that for every 6MHz, 1MHz is wasted.

Upstream services today may be composed of Impulse Pay Per View (IPPV), DOCSIS data, or voice data. The amount of actual data capacity and RF spectrum consumed by these services varies on a plant to plant basis. This example approximates 20Mbps allocated.

SDM Enabled Downstream Channels

SDM in the downstream is initially intended to use the unallocated portion of the 550MHz to 860MHz spectrum. Actual digital allocations will vary. This example illustrates 100MHz dedicated to QAM and the rest to Broadband Physics.

~20Mbps upstream, ~1.5Gbps downstream in this example

In this example, SDM is deployed above the QAM digital and provides additional 1Gbps of add digital capacity. This new capacity can be used for VOD, Subscription VOD, HDTV, extension of existing digital TV offerings as well as for new custom bandwidth services. Broadband Physics operates in the existing downstream without disturbing the other services.

SDM Enabled Upstream

SDM in the upstream stream is uniquely able to turn unused RF spectrum into usable data capacity. This example illustrates and additionaly 40Mbps being made available by turning on sub-bands only where there is available RF spectrum.

~60Mbps upstream, ~1.5Gbps downstream in this example

In this example, SDM turns unused but usable Hz into digital data capacity without disturbing existing upstream services.

SDM Choice for Analog Spectrum Replacement

Eventually, analog program channels will be retired in favor of digital channels. Broadband Physics provides the cable operator with the best replacement modulation.

~70Mbps upstream, ~6Gbps downstream in this example

In the ideal world, SDM would replace all analog channels. Reality will deprecate analog channels over time and will likely leave some around for a long time.

Note the upstream in this example. The IPPV spectrum has been converted to SDM. Once deployed, the cable operator can enable new spectrum coverage under management control, without installing new headend equipment, and without any truck rolls.

SDM Choice for Future QAM Replacement

Ideally, as presented in this example, SDM is the ideal choice as the only digital modulation to use int he cable plant. SDM does harness every Hz of spectrum with data capacity.

~150-200Mbps upstream, ~8.1Gbps downstream (860MHz system) in this example

Harnessing every Hz of an 860MHz HFC system would provide present ~8.2Gbps to the side of the home over existing HFC system.

Note these important points:

• The application of SDM enabled technology is applied in a step-wise incremental fashion
• Existing services are not disturbed
• The RF plant is not changed
• The technology scales to deliver the best capacity permitted by the HFC system