Smart City is a very interesting and broad field of research. In particular, one could suggest some services based on the principle of Swarm Intelligence (SI). SI can also be considered as Collective Intelligence (CI).
A swarm consists of numerous individuals. All individuals of a swarm try to help themselves in an intelligent way. Here is the following principle:
„Each for all and all for each“
and all individuals pursue the same common goal.
For example, all cars driving in a city can form a swarm with the goal to help each other intelligently in the search for free parking. So an intelligent city park system can be realized.
The SI principle could be used to develop the following services for Smart Cities:
There has been a surge of interest in "Representation Learning on Networks", which is a very young and exciting field of research. Doing some good work in this domain may bring you a lot of citations.