NAND flash memory has been widely used as a non-volatile storage for storing data. However, it requires a large amount of SRAM for executing program codes stored in it since it only supports page-based reads, not byte-level random reads. This paper proposes a new paging mechanism called RT-PLRU (real-time constrained combination of pinning and LRU) that allows program codes stored in NAND flash memory to be executed satisfying real-time requirements with minimal usage of SRAM. Moreover, the RT-PLRU is optimally configured in a developer-transparent way without giving any burden to the program developer. The developed technique is specifically applied to a media player program targeting a PMP (portable medial player). To the best of our knowledge, this is the first effort to use NAND flash memory as a code storage for storing and executing real-time programs with minimal usage of SRAM.

As the elderly population increases, elderly care using inexpensive technological means is becoming critical. This paper presents our prototype system that provides real-time indoor tracking of elderly residents and their belongings, which is essential to assisting and securing their independent living. For high-fidelity real-time tracking, we propose novel scheduling algorithms. Our scheduling algorithms are designed by harmonizing both sensing and communication signals and leveraging location awareness and mobility consciousness in order to improve tracking accuracy while reducing the energy consumption. We performed extensive experiments through both simulation and actual implementation. Our experimental result says that our scheduling algorithms can provide real-time tracking of residents within a 20 cm error bound in the typical range of human mobility.