MDSA: Multi-dimensional slotted ALOHA MAC protocol for low-collision high-throughput wireless communication systems

In wireless communication networks the collision rates increase due to the fact that multiple users may transmit simultaneously. Medium Access Control (MAC) protocols are employed to lower the collision rates through organizing the access to the communication channels. The simplicity of future wireless networks such as Wireless Sensor Networks (WSNs) implies the need for rather simple MAC protocols, which would, in-turn require collision resolution between the packets simultaneously transmitted by multiple users. Slotted-ALOHA is a simple MAC protocol which has a limited throughput (36%) that is still very low to support future wireless applications. The goal of this paper is to gain deep understanding of how to improve the throughput and reduce the collision rate of slotted-ALOHA MAC protocol. In particular, we propose a novel Multi-Dimensional Slotted ALOHA (MDSA) protocol that combines the advantages of TDMA, FDMA and CDMA. MDSA protocol utilizes three dimensional reservation bands, i.e., time dimension, frequency dimension and code dimension. In this paper, we show theoretically how the successful reservation rates increase and the collision rates decrease with MDSA under idle and noisy channel conditions, which qualify our proposed scheme to be a reliable MAC protocol for wireless communication systems.