Fine-grained Frequencies for Simultaneous Intra-Group One-to-All Dissemination

Simultaneous intra-group communication is one of the possible ways to handle the scaling issues in large decentralized systems. FDMA is an elegant strategy to carry out intra-group activities in parallel. However, due to increasing congestion in the licence free ISM bands, especially in the urban area, its hard to get enough number of good standard channels for multi-group setting in decentralized systems like IoT/WSN. In this work, we leverage concurrent transmission for efficient simultaneous intra-group one-to-all dissemination. Concurrent transmissions based strategies schedule the packet-transmissions in a special way so that the overlapping packets, instead of colliding with each other, result in constructive-interference or capture-effect. We propose a simple strategy to exploit this feature under concurrent transmission to achieve fruitful simultaneous intra-group communication in overlapping channels. Through extensive evaluation in testbeds for WSN/IoT under 2.4 GHz ISM band we show that, the proposed strategy can efficiently support simultaneous intra-group one-to-all dissemination even with allocation of channels having Center Frequency Distance (CFD) 1 MHz in most of the common group divisions. Experiments with a wide variety of group divisions also reveal that under concurrent transmission a CFD of 3 MHz and above can tolerate strong inter-group interference when the groups are quite mixed with each other which can be quite common specially when the nodes are mobile.