This paper presents a high-performance and low-power hardware architecture for real-time sound rendering on mobile devices. Traditional sound rendering algorithms require high-performance CPUs or GPUs for processing because of its high computational complexities to realize ultra-realistic 3D audio. Thus, it has been hard to achieve real-time rates on low-power mobile devices. To overcome this limitation, we propose a hardware architecture that adopts hardware-friendly sound-propagation-path calculation algorithms. We verified the function and performance of our architecture through its implementation on an FPGA board. According to ASIC evaluation with the 8-nm process technology, it achieves high performance with 120 FPS, low power consumption with 50 mW, and a small silicon area with 0.31 mm2, allowing real-time sound rendering on mobile devices.

Power management of sensor nodes is essential to maximize the lifetime of wireless sensor networks. Energy consumption of individual sensor node differs greatly depending on its type. Existing operating systems for sensor networks typically leave the power management of sensors to applications. Unless specific features of the sensors and batteries are considered in the application design, energy consumption may increase or the application may malfunction. In this paper, we define factors to be considered for sensor-specific power management, and then propose an automated sensor-specific power management system. The system is implemented on the multi-threaded RETOS operating system for sensor networks. The experiment results with various applications show that the proposed system reduced the energy consumption by up to 29% without modification of the application code.

This paper presents the design principles, implementation, and evaluation of the RETOS operating system which is specifically developed for micro sensor nodes. RETOS has four distinct objectives, which are to provide (1) a multithreaded programming interface, (2) system resiliency, (3) kernel extensibility with dynamic reconfiguration, and (4) WSN-oriented network abstraction. RETOS is a multithreaded operating system, hence it provides the commonly used thread model of programming interface to developers. We have used various implementation techniques to optimize the performance and resource usage of multithreading. RETOS also provides software solutions to separate kernel from user applications, and supports their robust execution on MMU-less hardware. The RETOS kernel can be dynamically reconfigured, via loadable kernel framework, so a application-optimized and resource-efficient kernel is constructed. Finally, the networking architecture in RETOS is designed with a layering concept to provide WSN-specific network abstraction. RETOS currently supports Atmel ATmega128, TI MSP430, and Chipcon CC2430 family of microcontrollers. Several real-world WSN applications are developed for RETOS and the overall evaluation of the systems is described in the paper.

This demonstration shows the programming development suite of the RETOS operating system for sensor networks, which provides a robust and multithreaded programming interface to application programmers. We first demonstrate how to build the RETOS kernel on the TI MSP430, Atmel ATmega 128 and Chipcon CC2430 family of microcontrollers. The application or a kernel module is then compiled and disseminated, via wireless channel, to the target motes. The GUI-based RMon network management tool for RETOS is also demonstrated to monitor the networked sensors, and even to control the system's parameters or applications running on them via a remote shell. The system is demonstrated to run on a mixed set of MSP430, ATmega128 and CC2430-based motes. Overall, our demonstration will convince attendees of the programming convenience of developing sensor network applications using RETOS, which is, indeed, a mature and practical system that can be used to develop real-world applications.

Wireless sensor network technology has found diverse applications in numerous fields. As the networking technology is refined in many ways, the need for system modulation with effective performance becomes essential. A multitude of architectures, which includes system abstraction and layering, has been proposed to solve the need at the operating system level. However, previous efforts do not qualify for networking architecture required by sensor networking, since they are aimed at hardware abstraction or protocol-based layering. In this paper, we classify developers into kernel, network and application developers and propose a network architecture that enables those developers to program independently. Network stack is separated into three different layers; MLL, NSL, DNL. This three-layered architecture provides an effective programming environment to sensor network developers by minimizing modification of other layers and maximizing reusability of the networking module. To validate the proposed mechanism, we implemented and assessed the performance with a few network algorithms and applications, based on the RETOS, which supports a dynamic loadable kernel module