Mathematical structures can be found in the core of most products and systems in information and communications technology (ICT). The mathematical structures not only make the system work but they also have a direct impact on the efficiency of the system. One may strive to get the most benefit out of the available power and energy, or alternatively minimize power and energy in systems that meet given design criteria. Consequently, this is about research and disciplines that were green decades before the term green was introduced in this setting. The current project is specifically about mathematical structures for communications in large networks, such as mobile phone systems and the internet, and utilizes a variety of techniques and tools from algebra, algorithmics, coding theory, combinatorics, and design theory.