SpectrumWars is a programming game where players compete for bandwidth on a limited piece of a radio spectrum. Its aim is to show the problems in spectrum sharing in an entertaining way. It captures the competition between various groups of users. Such competition is increasingly a factor in wireless communications as users demand more data in an even increasing variety of situations.
SpectrumWars extends the concept developed by P. Sutton and L. Doyle in The gamification of Dynamic Spectrum Access & cognitive radio by changing the role of the human competitors. In the initial concept, competitors are directly controlling transceivers via joystics. In this SpectrumWars implementation, they instead develop an algorithm that controls the transceivers in their place.
The competitive aspect of SpectrumWars was inspired in part by the DARPA Spectrum Challenge. However the goal here is to make the game as accessible and as fun as possible. The trade-off between realism for simplicity is heavily skewed towards the latter. For example, the interface between the player’s code and the transceiver is greatly simplified, limiting the number of transceiver settings to just three: radio channel, bit rate and transmission power. This kind of a simplified toy-like interface was inspired by existing programming games, like the venerable RobotWar and its clones.
One aspect of real-life radio communications was not sacrified though: SpectrumWars games run on real hardware and use real radiofrequency spectrum. While a simulator is available to ease the development and debugging of player code, the SpectrumWars challenge runs on hardware provided by partners of the CREW project and takes place on real wireless testbeds.
Overview of the game¶
Competitors develop their algorithms using the Python scripting language. In a single game, two or more algorithms (players) compete with each other to transfer some useful data from a source to a destination as quickly and as reliably as possible. A good player for example will avoid interference from other players and the environment.
Players are aided in this task with the help of a spectrum sensor. In the game, the spectrum sensor is a centralized, simplified spectrum analyzer that is always available to the players. An algorithm can query it to get an up-to-date picture of the occupancy of the spectrum in the form of a power spectral density function.
The nature of the data being transferred is not directly known to players - it could conceivably be a machine-to-machine link sending sensor data, or it could be someone on a coffee break browsing their favorite social networking website. The player code only controls the connection and in fact does not need to concern itself with the payload part of the packets it is sending over the air.
Each player is given control of two transceivers (radio front-ends). For the purpose of the game, payload only needs to go from one transceiver (called source) to the other one (called destination). The players make use of a simple interface that provides basic control over the radio.
The separation between the source and the destination poses another challenge the players must overcome. There is no reliable back channel to use for synchronization between the two ends of the radio link. A rendezvous strategy is therefore required for all but the most simple algorithms.
Players are ranked by different statistics, like average packet loss and throughput. Different challenges are possible within the basic SpectrumWars framework. Some challenges might give more weight to the power efficiency of the players, while others might favor resilience against interference. Some might encourage players to intentionally interfere with competitors. Again some others might introduce an interfering spectrum user to the testbed where the game is played, but that is external to the game itself.