IEEE Future Directions
Related Articles
Communications technologies – part 2
In explicit communications there are a number of parties involved and they establish a sort of handshake providing feedback on the reception and possibly further information to steer the evolution of behaviour of the parties involved. Although explicit communications is not characterising autonomous systems it is, and will be, often used to increase the overall awareness and influence, in more precise ways, the behaviour of each autonomous system.
A crucial aspect related to explicit communications in autonomous systems is the demand for inherent flexibility of the communications structure, both at physical and logical level. In other words: with autonomous systems one cannot define “a priori” the communications rules (because one does not know –in general- whom one will be communicating with) but should rather provide a communications framework to support interactions among undefined parties. Within this communications framework there are some fixed, standardised, rules allowing the communicating partners to enter into a meaningful communication.
It is a bit like communications among human beings. Although we seldom notice, a lot of communications takes place in an implicit form. You walk on a sidewalk, you see a person coming your way and you slightly move to the right (in most of Europe, probably to the left in UK!) and the other person does the same. All of this takes place naturally and without any explicit acknowledge. If you talk to a person you are relying on a common syntax/semantics and it works pretty well. Sometimes though, you are facing a person of a different nationality and you may start your conversation by saying “Do you speak English?”. A positive answer would shift your communications framework to a specific set of rules and communications will go on within that set from then on. If it turns out that you are not sharing a common set of rules (the other party only speak Tagalog and that is out of your communications possibilities) you may still try to set up a more limited communications using gestures, drawing images on a piece of paper and so on. It is not as good as sharing the rules provided by a spoken language but still it works.
However, if you happen to meet a person that is deaf your voice will not work. The physical layer is not compatible. You need to turn to a different physical layer, like gesture, although you may not know the “language of signs” and so you will be using a subset of communications expressions like the one you would be using with a Tagalog speaking person.
The situation for explicit communications among autonomous systems is pretty similar, from a conceptual view point. First there is the need of sharing a common physical layer, in case of wireless communications this means to use the same frequency.
Wireless systems use a variety of frequencies because they provide a variety of characteristics that can serve in different situations. Higher frequencies can potentially carry broader bandwidth but over shorter distances, vv lower frequencies have better propagation characteristics but in general support less bandwidth (and are more crowded). There are a variety of standards for radio communications and significant work remains to be done to leverage on them all in a situation where autonomous systems may need to interact with a variety of players with no a priori defined protocols.
WLAN communications (like IEEE 802.11) can present challenges indoor if the autonomous system has to roam in a large compound since propagation is limited by walls, particularly if these are hard pressed concrete. In this case pervasive infrastructures (with beacons and repeaters) may be required. In cases where there is a multitude of autonomous systems the communication fabric can be created autonomously. In the future this solution (given the increase in number in autonomous systems and more generally smart connected devices) seems to be the most promising.
In case of autonomous vehicles industry is at work to agree on standards both at the physical level (frequencies) and transport layers (2-4). The increased capabilities of communications chips will support multiple frequencies communications so that an autonomous system will be able to communicate using a broad range of frequencies and agreeing with the other party(ies) which one to use at a particular time.
Industry 4.0 is another area where communications standards for autonomous systems are being developed.
