Most inter-agent communication models assume reliable point-to-point messages passing with negligeable communication costs. In particular, KQML assumes point-to-point message passing, possibly with the aid of facilitator agents [3]. Nonetheless, KQML performatives could be used for the content portions of our proposed communication scheme. KQML does not address the problems raised by having a single, low-bandwidth communication channel.
With only a single team present, a situation similar to the one considered here is examined in [7]. In that case, like in ours, messages sent are only heard by agents within a circular region of the sender. Communication is used for cooperation and for knowledge sharing. Like in the examples presented in the soccer domain, agents attempt to update each other on their own internal states when communicating. However, the exploration task considered there is much simpler than soccer, particularly in that there are no opponents using the same communication channel and in that the nature of the task allows for simpler, less urgent communication.
Even when communication time is insignificant compared to action execution, such as in a helicopter fighting domain, it can be risky for agents to absolutely rely on communication. As pointed out in [10], if the teammate with whom an agent is communicating gets shot down, the agent could be incapacitated if it requires a response from the teammate. This work also considers the cost of communication in terms of risking opponent eavesdropping and the benefits of communication in terms of shifting roles among team members. However, the problems raised by a single communication channel and the possibility of active interference are not considered, nor are the challenges raised when communication conflicts with real-time action.
A possible application of the method described here is to robots using audio communication. This type of communication is inherently single-channel and low-bandwidth. An example of such a system is the Robot Entertainment Systems which uses a tonal language [4]. Agents can communicate by emitting and recognizing a range of audible pitches. In such a system, the number of bits per message would have to be lowered, but the general techniques presented above still apply.