In the near future, more than two thirds of the world’s population is expected to be living in cities and hence, with the aim of being proactive and finding innovative and sustainable solutions, governments have made smart cities one of their priority areas of research.Smart cities are sustainable, inclusive and prosperous greener cities that foster enabling smart Information and Communication Technologies (smart ICT) such as Internet-of-Things (IoT), cloud computing and big data to better facilitate services such as mobility, governance, utility and energy management.As these services depend heavily on data collected by sensors, Unmanned Aerial Vehicles (UAVs) have quickly become one of the promising IoT devices for smart cities thanks to their mobility, agility and sensory payload adaptability. UAVs found use in a wide array of applications expanding beyond military to more commercial ones, ranging from traffic monitoring, mapping, construction and industrial sites surveillance to parcel delivery, but also more demanding applications that require UAVs to operate in heterogeneous swarms in a shared low altitude airspace over populated areas. However, as the number of UAVs continues to grow and as sensing, actuation, communication and control become increasingly sophisticated with the complexity of their applications, UAV development in smart cities is faced with a set of fundamental challenges in their safe operation and management. stressing the need for establishing globally harmonised regulations and internationally-agreed-upon technical standards to keep-up with and govern the rapid technological advancements, as well as ensure a fair economy by encouraging market competition and lowering barriers to entry for newcomers.One of the main obstructing barriers hindering the realisation of such complex applications in smart cities is the lack of a UAV-specific localisation and tracking system which is resilient, scalable and efficient, allowing the interoperability and integration of UAV swarms in a limited and congested airspace.In this work, we focus on studying the fundamental technical requirements, specifications and functions of such a UAV localisation and tracking system and explore its relationship to and importance in 1) optimising path planning, flight scheduling and utilising shared airspace, 2) collision avoidance and conflict resolution in highly populated residential areas and 3) addressing privacy and data protection concerns that could arise from UAV monitoring and surveillance applications. Furthermore, for each of the three aspects listed above, we analyse the current standardisation efforts such as those put forth by EASA, EUCARE WG 73 and ISO TC/SC16 on UAV systems, ISO JTC1/SC41 on IoT and related technologies and ISO JTC1/SC27, EU Directive 95/46 EC and GDPR on security, privacy and data protection, in order to identify and prioritise future research questions in relation to UAV localisation, with the aim of making a contribution towards narrowing the gap between research and existing technical standards by encouraging multi-mode standardisation.