High-throughput time group access SS-CSMA/CA for wireless ad hoc networks with layered-tree topology

Multi-hop packet transmission error due to packet collision is a serious issue for realizing large-scale wireless ad hoc networks. In order to solve the issues, a multicode-reception spread-spectrum (MCR-SS) -CSMA/CA was proposed as a multiple access scheme for layered-tree networks. This paper proposes a new SS-CSMA scheme that combines a time group access (TGA) technique with the above multiple access scheme to gain higher interference reduction between nodes. The proposed scheme divides the layered-tree network into upper subnets group and lower subnets group, thus reducing collision probability among subnets. Network throughput and data delivery ratio for the proposed scheme are analyzed by simulations based on the IEEE 802.15.4/ZigBee specification. Simulation results show that the proposed scheme can improve network throughput remarkably.