Relevant: "Never underestimate the bandwidth of a station wagon full of tapes."

That quote has always bugged me. It's dimensionally wrong: a station wagon doesn't have bandwidth.

Bandwidth (in the sense intended here) is measured in bits/second: how do you measure that from a station wagon [full of mag tapes]?

Now a freeway full of station wagons ... that has bandwidth.

If it takes an hour to copy a terabyte of data to a tape, put it in a car, drive to a location and read the tape, you just transported 8796093022208 bits in 3600 seconds, or about 2443359173 bits/second.

edit: I always understood the quote as "the [potential] bandwidth"- the bandwidth that can be available using the station wagon as physical infrastructure.

Firstly, that number is a function of how far apart your particular origin and destination are, so it's not intrinsic to the station wagon.

And secondly, you just measured latency there, not bandwidth.

Unless I'm wrong, they've measured both: Latency is 1 hour (time it takes a packet to go from source to destination), bandwidth is that number they quoted.

Latency is 1 hour, but to get bandwidth you need to divide not by 1 hour but by the time between successive station wagon departures. For example if you only have one station wagon and driving back after copying the tapes takes a further 30 minutes, then the denominator is 5400 seconds and so the system bandwidth is 50% less than the number quoted.

Latency is greater than 1 hour, if it takes an hour to copy the data to the tapes. You've got to get them to the destination and copy them off after that.

>If it takes an hour to copy a terabyte of data to a tape, put it in a car, drive to a location and read the tape

That's 1 hr latency, unless I'm mistaken. Latency doesn't include disk operations on the client side, does it? Is latency time between a signal being sent and received, or between sent, received, and acknowledgement sent/received?

ie, is latency time(client->SYN->server->SYNACK->client->ACK->server), or time(client->SYN->server)?

Bah. My reading comprehension not so good.

>edit: And given trends in solid-state drives, local storage will be cheaper and more energy efficient than a wireless network for a long time.

At some point, though, you get diminishing returns. If all you're doing is playing mp3s at 192 kbit/s, existing wireless is fine and future wireless will be more than adequate. There's no need to add the expense of putting local storage on a mobile device if you can achieve the same end cheaper with cloud hosting.

Now, this is all academic, as we're talking about a radio, and I don't think they're likely to be around by then. Whether or not a device includes local storage will be an economic decision given its intended usage and market conditions of the time, which nobody can predict with great certainty.