Simultaneous Intra-Group Communication: Understanding the Problem Space

In an IoT-based large decentralized smart-system, many devices need to collaborate with each other to achieve the desired goals in a time and energy-efficient manner. Simultaneous communication is one of the key tools to solve the scalability issues in the underlying communication protocols used in these systems. Frequency Division Multiple Access (FDMA) has been one of the elegant strategies to support simultaneous communication. However, massive sharing of the licence free ISM bands among many technologies and many devices results in fast depletion of the availability of the orthogonal frequencies/channels for use in the IoT-systems. To address this resource scarcity, there have been efforts which demonstrate that truly orthogonal channels may not be always necessary to achieve fruitful simultaneous communication. Recent studies have shown that the use of concurrent-transmission can appropriately exploit special radio-features to achieve in-parallel communication even without changing channels. This article summarizes the full spectrum of these works and brings forth an aerial view of the overall problem space. An approximate division of the problem space is also derived and the existing solution approaches are positioned in their respective zones.