Existing Delivery System Problems
The increasing worldwide demand for rapid, low-latency and high-volume communication of information to homes and businesses has made economical information distribution and delivery increasingly important. As demand has escalated, particularly fueled by the widespread adoption of the Internet, the need for economical high-speed access by end-users located at millions of locations has ballooned as well.
As requirements have changed, existing systems and networks which were initially pressed into service for this purpose have proven to be inadequate. To date, although a number of approaches have been tried and used, no single clear solution to this problem has emerged. This problem has been termed "The Last Mile Problem".
As expressed by Shannon's equation for channel information capacity, the omnipresence of noise in information systems sets a minimum signal-to-noise ratio (shortened as S/N) requirement in a channel, even when adequate spectral bandwidth is available. Since the integral of the rate of information transfer with respect to time is information quantity, this requirement leads to a corresponding minimum energy per bit. The problem of sending any given amount of information across a channel can therefore be viewed in terms of sending sufficient Information-Carrying Energy (ICE). For this reason the concept of an ICE "pipe" or "conduit" is relevant and useful for examining existing systems.
The distribution of information to a great number of widely separated end-users can be compared to the distribution of many other resources. Some familiar analogies are:
- blood distribution to a large number of cells over a system of veins, arteries and capillaries
- water distribution by a drip irrigation system to individual plants, including rivers, aqueducts, water mains etc.
- Nourishment to a plants leaves through roots, trunk and branches
All of these have in common conduits which carry a relatively small amount of a resource a short distance to a very large number of physically separated endpoints. Also common are conduits supporting more voluminous flow which combine and carry the many individual portions over much greater distances. The shorter, lower-volume conduits which individually serve only one or a small fraction of the endpoints, may have far greater combined length than the larger capacity ones. These common attributes are shown to the right.
Read more about this topic: Last Mile
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