Scalable channel allocation and access scheduling for wireless internet-of-things

Wireless communication channels are a scarce resource shared among multiple users in either scheduled or randomized fashions. We challenge a few design aspects of the widely used IEEE 802.11 MAC in wireless sensor networks (WSNs), such as the use of RTS, CTS, and ACK handshaking and the binary exponential backoff mechanisms, and argue that these key mechanisms incur high channel overhead and cannot effectively eliminate hidden terminal problems in multi-hop scenarios. Instead, we propose a set of efficient grid-based channel allocation and access scheduling algorithms using Latin squares, called as GAALS, for scalable WSNs with single-radio multi-channel communication capabilities. Using nodal location information and forming grids over the WSN deployment area, GAALS maps Latin squares to the grids, and dynamically assigns multiple channels to the WSN grids for channel access scheduling purposes. The fairness and scalability of GAALS are analyzed and evaluated in multiflow multihop WSNs with multi-channel capabilities. The results show that GAALS achieves much better performance than other multichannel protocols.