Extended-range Wireless Sensor Networks with enhanced IEEE 802.15.4 CSMA/CA

An extended-range Wireless Sensor Network (WSN) technology is presented in this paper. The proposed technology is based on a cross-layer optimization of the IEEE 802.15.4 standard. In the physical layer, the use of directive and adaptive phased arrays is proposed for the WSN gateways. Consequently, a neighbor-cooperative CSMA/CA algorithm is proposed to alleviate the hidden-terminal problem that is aggravated with the use of directive antennas on the one side of the communication links (asymmetric links). With the proposed technology, a 3-fold increase of the single-hop range is achieved and transmission efficiency of the MAC is improved with minimal impact on the overall throughput, protocol complexity, overhead efficiency, and scalability.