On the Optimal Interrogator Design for the EPC-Global Class-1 Gen. II RFID System

The major problems faced by the interrogator of now existing radio frequency identification (RFID) systems are: 1.) the error rate of the signal detection are limited due to both of the low receive backscatter signal power and the mismatched symbol period estimates; and 2.) The system efficiency on tag identification is affected by the collision among the backscatter signals, especially in the case of large amount of tags. Therefore, aimed at the above two problems, in this research project, we propose the optimal baseband signal processing scheme for the interrogator so as to enhance the integrity of detected signals, reduce the collision rate of the backscatter signals and thus boost up the system performance. This research project is a two-year project. The EPC-Global Gen. II standard will be used as the running example for the illustration of our developed algorithm. In that standard, the communication protocol between interrogator and tags is classified into 1.) physical layer (PL), and 2.) tag identification layer (TIL). In the first year progress of this proposal, to mitigate the error rate of the backscattered signal detection, we are planning to use the structure of the data-encoded signals to develop a series of robust signal sequence estimation algorithms so that the joint signal sequence estimation and data frame synchronization can be fullfilled simultaneously. In the second year progress of this proposal, by using the antenna array at the interrogator, in conjunction with the collision avoidance scheme disclosed in the EPC-Global Gen. II standard, we are going to design the transmit /receive beamformers to build up a space-time-division-based grouping scheme for the collision avoidance of the advanced RFID systems. This scheme will classify the tag distribution zone into different space-time sectors of various spatial coverages, and then tags located in each space-time sector will be scheduled to be identified via the use of transmit/receive beamformers at the interrogator. It is expected that the collision rate of the proposed space-time-based grouping- scheme can be efficiently decreased as compared to conventional approaches.

Project ID:PB9907-4006
External Project ID:NSC99-2221-E182-023-MY2