Power has become a critical aspect in the design of modern wireless systems, especially in passive device nodes such as Radio Frequency Identification (RFID) tags, sensor nodes etc. Passive RFID tags in particular use simple logic that is used to respond with a unique code or data to identify objects when queried by an interrogator, whereas wireless passive sensor devices use microcontrollers for sensor data processing. There is a need for a Minimal Instruction Set Architecture (MISA) for such passive nodes with regard to low power. In this context, passive node capabilities need to be explored, possibly to suit target applications, in order to enable more than just identification and perhaps less than those of a conventional microcontroller Instruction Set Architecture (ISA).
This dissertation research demonstrates a low-power wireless distributed processor architecture concept. The data and program instructions are stored on a powered interrogator providing wireless supervisory control for the remote passive node that has a basic processing core called the remote execution unit (REU). The interrogator and the passive node (REU) combination can be viewed as a complete processor or as multiple processing units forming the basis for a wireless distributed Single Instruction Multiple Data (SIMD) processor.
This research introduces and investigates the REU architecture using an 8051-MISA with the goal of reducing power consumption of the system. A novel low power data-driven symbol decoder-CRC along with the 8051-MISA based execution core design form the frontend and core part of the REU architecture. Clocked and asynchronous digital logic implementations of the REU core design are presented and correspondingly the power, area and speed comparisons are also provided.
Lack of strong support by commercial CAD tools is a major hurdle for synthesis of asynchronous designs. This research also presents a high-level design flow used to implement the asynchronous logic for the REU using traditional clocked CAD flows. This research work demonstrates immense potential to realize low power wireless passive sensor nodes for biomedical, automation, environmental, etc., applications especially while providing the basis for a programmable passive remote unit for distributed processing
