Separate coverage from capacity

Nigcomsat 1R carries equipment in C, Ku, Ka and L frequency bands. The operator describes different beams rather than one identical service everywhere. A footprint identifies an area associated with a beam; it does not show that every building has a suitable terminal, a clear view, electrical power or an active connection. Frequency band and beam must match the equipment and service being considered.

Think of a coverage outline as the beginning of a planning question. A site can lie inside that outline but have an obstructed view or unsuitable equipment. A site outside one beam might fall within another, with different requirements. The receiving dish in this course illustrates ground hardware in Nigeria, but its shape alone cannot identify its satellite or subscribed service.

The operator’s leasing specifications describe Ku-band channels with 31.5 MHz of bandwidth. Megahertz measures a span of radio frequency; megabits per second measures a rate of data transfer. Converting between them requires assumptions about modulation, error correction, signal conditions and overhead. A wider channel can offer more opportunity to carry data, but its MHz value is not itself an internet speed.

For a deliberately simplified example, suppose a 10 MHz channel carries an average of 2 useful bits per second for every hertz after the losses and overhead included in our model. Multiply 10 million by 2 to obtain 20 million useful bits per second, or 20 Mb/s. If usable efficiency falls to 1 bit per second per hertz, the modeled rate becomes 10 Mb/s. These are teaching assumptions, not measured NigComSat performance.

Now imagine a 40 Mb/s usable pool shared equally by eight continuously active sites. With no other bottleneck in this model, each receives 5 Mb/s. Adding eight more equally active sites without adding capacity reduces that equal share to 2.5 Mb/s. The satellite footprint has not changed, yet the rate available to each site has. Real networks may allocate resources unequally or dynamically; the arithmetic describes only the stated sharing rule.

Before comparing two proposals, ask whether their numbers refer to channel width, total shared capacity, a maximum burst rate or a committed allocation. Also identify the direction of traffic. A download figure does not automatically describe the return path. Clear units and allocation rules are more informative than treating one large number as a complete description of service quality.

Share a fixed usable capacity