## Synchronization to GPS Time

In the science side of my blog, I have frequently introduced concepts from special relativity that speak to limitations in synchronizing clocks that are separated by appreciable distances. In practice, the speed of light is about 1 foot per nanosecond. This seems rather odd then, in the context of metropolitan area paging networks that cover regions as large as San Diego to northern greater Los Angeles on a side and with distances between sites of tens to hundreds of miles. In what way can such systems be said to “simulcast” if simulcasting means “broadcasting...

Read More## Big fat paging bits

Back to our sponsor, paging, for a moment. In my very first post here, I took a comparative look at some distinctions between modern paging and digital cellular systems. I want to return to that idea, but with a slightly different point of view. This time, I want to consider the composition of the information-carrying components of these systems on a photon-by-photon basis. First, let’s go back to the basic aspects of a bit. A base station (BS) transmitter radiates electromagnetic power in sending a communications symbol for a certain amount of time. In the case of a paging system, say...

Read More## Noise: white, pink, brown, black, and buffers

This post is a continuation of the previous one on network congestion. A white noise is one in which each sample is uncorrelated with any other. A white Gaussian noise is one in which the samples are distributed according to a normal curve with a stable mean and variance. The power spectrum of a white noise process is uniformly flat at all frequencies. One way to think about this property is to say that there is equal power in equal frequency bands. Another “brand” of noise is pink noise. The power spectrum of a pink noise falls off as 1/f and so this form of noise is often...

Read More## Einstein, Hurst, and network congestion policy

We begin our story with good old Albert Einstein and his considerations of Brownian motion. In 1905, Einstein delivered four papers for publication that, in turn, addressed the photoelectric effect, Brownian motion, special relativity, and energy-mass equivalence. He could have been swept from the earth in 1906 and he’d still have been rightly famous for his work of 1905. Over 100 years later, folks are still struggling with the meaning of his work in that year. You can read what Albert had to say about Brownian motion for yourselves. Let’s turn to the bit on Brownian motion for...

Read More## The statistics of offered load

Almost everyone with a high school education is familiar with the Gaussian or Normal distribution. One reason for this is that the student’s scores from exams or complete terms are “graded on a curve”; that curve being a Normal probability law. The two important parameters of the Normal curve are its mean and standard deviation. The mean is a measure of its “central tendency”; that is, the single and preferred location around which the most probable values are bunched up. The standard deviation measures the spread of the distribution. A discrete variation of the Normal curve is...

Read More## COAM Equipment

COAM is an acronym for “customer owned and maintained”. It is used in the context of who owns the mobile device that the customer is using. This may seem a rather odd question, especially in the context of current cellular business models; but the notion of COAM in the paging sector was pioneered by my previous employer, PageMart. Of course, if your business has to buy or subsidize all of the mobile equipment in your subscriber pool, then that constitutes a significant capital investment in your operations. Naturally, the return on this investment is the cash flow that the...

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