Fall 2003 Issue

Is All Data Acceptable Data?

By Neil Sablatzsky, K8IT

If I sent a data packet from my computer to yours via a legally identified transmission according to the Amateur Radio FCC Part 97 rules and regulations, would the data packet be legal? This column will explore this question and many related issues. First let’s start by reading a letter.

Correspondence

The following was sent to me by Ken Patterson, N5EQT:
While on the way home from Ham-Com 2003, my sons (Aaron, KC5TEF, age 19; Joshua, KC5TEG, age 18; and Michael, KC5TEH, age 20) and I discussed Gerry Creager, N5JXS’s HSMM presentation and came up with an interesting idea. During the presentation, Gerry mentioned that interactive games could be one use of HSMM. My sons and I think this application could give HSMM and amateur radio in general a real boost in interest and activity. Let me explain.

Players of multiplayer and First Person Shooter (FPS) games such as CounterStrike <http://www.counter-strike.net> and EverQuest <http://everquest.station.sony.com> desire the lowest transmission latency (pings) possible. Currently, cable-modem and DSL users have a 25- to 30-millisecond ping. If the same multiplayer games were played via HSMM, the pings would drop to about 6 milliseconds. This reduction in latency is very significant. It could easily make the difference in a player’s ability to win.

A ping is a command that initiates an Internet Control Message Protocol (ICMP) Echo Request and Echo Reply message. These messages must travel to their destination and return to their sender, where the time required for the round-trip is measured by the originating sender. Think of an Internet ping much like the sonar pings used for decades by submarine crews to measure objects within their path.

Low pings are good. High pings are bad.

When a person is playing over the Internet using a client/server-based system, data flows from the server to the individual client (user). Anything the client does has to register with the server before it can happen in-game. For instance, if player A and player B in a First Person Shooter game were to fire at each other at the same time, the player with the lowest ping would hit the target first simply because that player’s data registered with the server first. As you can tell, this is an obvious advantage in a game. The difference between winning and losing a game can come down to which player fired—or whose data actually reached the server—first.

Multiplayer games such as CounterStrike utilize User Datagram Protocol (UDP) transmissions. This protocol is a connectionless IP datagram service that guarantees neither delivery nor correct sequencing of delivered packets. The use of UDP by games such as CounterStrike is verified every time the user joins a CounterStrike server to play a game. UDP transmissions are most commonly used by streaming multi-media services, such as Microsoft’s NetMeeting.
 

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