Low data rate communication systems have spanned across many technologies including land mobile radio, cellular, satellite, point-to-point wireless and even wired POTS systems. The high cost of implementing these solutions has limited high volume, wide area deployment for low data rate solutions. The high cost is due to “last mile” implementation including controller unit, dedicated links and service fees.
The prior art communications systems for sensors that detect and track events are large and expensive so they cannot be widely distributed in a cost effective manner. Further, event detection is heavily dependent on the characteristics of the sensors attached to the radios. Further, most existing sensors are limited in detection range and can only be deployed in a limited number. Limiting the number of nodes make sensor event detection difficult, and the high cost of radio nodes makes wide deployment financially prohibitive. Recent sensor research has resulted in reducing sensor size and cost so that a global sensor network for pre- and post-event supervision and reporting is now feasible. However, these sensors need a reliable wireless network to process and distribute sensor data to central operation centers for supervision and control.
Thus, there is a need to develop cost effective sensor nodes with a reliable wireless data network for collaborative detection, location, assessment, and tracking of events. A low cost, wireless network sensor node with long battery life that is capable of being deployed in many different environments can achieve such a solution. A complete wireless sensor network includes access points, or gateways, into existing data infrastructure for reachback communications to command and control centers.
There are several issues with current wireless sensor networks which need to be addressed: scalability to provide a global network and selection of radio RF frequency and waveform. Automatic link communications of each node is critical for cost effective deployment for a global network. There is no global spectrum allocated by international regulations or standard waveform identified, so a single RF waveform solution is not feasible.