Gwangil Jeon

Integrating subscription-based and connection-oriented communications into the embedded CORBA for the CAN bus

The authors present the design of CAN-CORBA, an environment-specific CORBA for CAN-based distributed control systems. The ORB core of the CAN-CORBA has the following properties. (1) It supports subscription based group communication as well as the classical connection oriented point-to-point communication of CORBA; as a result, it better services the data multicasting requirement of typical control systems. (2) It significantly lowers the amount of message traffic required for each CORBA method invocation so that even the slow broadcast bus of the CAN can tolerate the overhead of CORBA method invocations. To seamlessly integrate two communication schemes into our extremely light-weight ORB, we design a transport layer protocol on the CAN that can support up to four different upper level protocols. We have implemented the CAN-CORBA on the mArx real time operating system developed at Seoul National University. Our experiments clearly demonstrate that it is feasible to use CORBA in developing distributed embedded control systems possessing severe resource limitations.

Energy aware routing with dynamic probability scaling

The goal of energy aware routing algorithms is to increase the lifetime and long-term connectivity of the wireless sensor networks. However, most of those algorithms do not use the newest states of nodes for retrieving routing information. In this paper, we propose an efficient energy-aware routing algorithm for wireless sensor networks. In our algorithm, the energy drain rate and residual energy of each sensor node are used for selecting candidate routes. Information is retrieved with energy awareness per almost every communication. Simulation results show that our approach outperforms the previous works with respect to long term connectivity by as much as 30%.

Femtocell power control by discrimination of indoor and outdoor users

Femtocells are usually deployed in an indoor environment to provide in-building coverage enhancements. However, femtocells get to provide services for not only indoor users but also outdoor users in vicinity. Without the knowledge from the femtocell of whether the serviced users are located indoor or outdoor, the outdoor users are likely to experience low Quality of Service (QoS) due to inefficient coverage management and power control from the femtocells. To resolve such problem, this paper provides a method of discriminating indoor and outdoor users in a simplified way. Also, based on such discrimination, a downlink power control scheme is provided. Through simulations, we show that the discrimination procedure achieves 97.48% of correct determination in environment with low shadowing effect, and 89.41% of correct determination with high shadowing effects. Also based on the proposed discrimination procedure, power control exploiting such information provides a 31.96% reduction of outage probability, and a 8dB performance gain for cell-edge HUEs, compared to a power control with random discrimination.

A dynamic multiagent-based local update strategy for mobile sinks in wireless sensor networks

Recently, several geographic routing strategies considering a mobile sink node have been proposed for wireless sensor networks. A mobile sink node should frequently update its location information in source nodes for successfully receiving data from the latter. However, frequent location updates from the mobile sink node may result in the consumption of too many network resources. In this paper, we propose an efficient multiagent-based location update strategy for a mobile sink node in wireless sensor networks. Agent nodes that are located on the path between the source node and the mobile sink node contain the location information of the mobile sink node. In addition, the agent nodes are changed dynamically to maintain the approximate shortest path between the source node and the mobile sink nodes. We analyze the performance of the proposed scheme by performing simulation using Qualnet 5.0.

The robot software communications architecture (RSCA): embedded middleware for networked service robots

In this paper, we present a robot middleware technology named robot software communications architecture (RSCA) for its use in networked home service robots. The RSCA provides a standard operating environment for the robot applications together with a framework that expedites the development of such applications. The operating environment is comprised of a real-time operating system, a communication middleware, and a deployment middleware. Particularly, the deployment middleware supports the reconfiguration of component-based robot applications including installation, creation, start, stop, tear-down, and un-installation. In designing RSCA, we have adopted a middleware called SCA from the software defined radio domain and extend it since the original SCA lacks the real-time guarantees and appropriate event services. We have fully implemented RSCA and performed measurements to quantify its run-time performance. Our implementation clearly shows the viability of RSCA

Energy aware routing based on adaptive clustering mechanism for wireless sensor networks

The main goal of research concerning energy aware routing algorithm for wireless sensor network is to increase the lifetime and long-term connectivity of the wireless sensor networks. However, most of energy aware routing algorithms do not take into account the clustering mechanism efficiently. In this paper, we present an efficient energy aware routing algorithm for the wireless sensor networks. In our algorithm, the data aggregation technique and adaptive clustering mechanism are considered for reducing and compacting the cumulative size of packets on the wireless sensor networks. Simulation results show that the energy usage of EAR-ACM is significantly reduced compared with the previous clustering based routing algorithm for the sensor networks.

Energy efficient program updating for sensor nodes with flash memory

Updating sensor node programs is an essential task for maintaining stability and modifying the characteristics of wireless sensor networks. The updating mechanism must consider energy and memory efficiency, because of resource constraints of sensor nodes. In this paper, we propose a novel program updating mechanism, which considers resource constraints of sensor nodes. The proposed mechanism was designed for sensor nodes with the NOR flash memory. This is generally used to store program image. It was designed to minimize the number of flash write/erase operations, which consume a great deal of energy, and to provide wear-leveling for the NOR flash memory. We set a function as the basic unit of program updating, and partition a function into fixed-sized blocks that can be separately relocated in memory. Experimental results show that the proposed mechanism outperforms other mechanisms in terms of energy, memory and wear-leveling for flash memory.

A partitioning method for efficient system-level diagnosis

We propose a partitioning method for an adaptive distributed system-level diagnosis in arbitrary network topologies. It utilizes a biconnected component as a partitioning unit. In an adaptive distributed system-level diagnosis, testing assignment algorithm is performed before each node performs actual diagnosis to reduce the number of tests in the system. Existing testing assignment algorithms adopt non-partitioning approach covering the whole system, so they incur unnecessary extra message traffic and time. In our method, the whole system is partitioned into small groups (biconnected components), and testing assignment is performed within each group. By exploiting the property of an articulation point of a biconnected component, initial testing assignment of our method performs better than non-partitioning approach by reducing the number of nodes involved in testing assignment. It also localizes the testing reassignment caused by system reconfiguration within the related biconnected components only. It is shown that our system-level diagnosis method is correct, and the number of messages required for testing assignment of our method is smaller than that of the previous non-partitioning methods. Comparisons with other partitioning approach are also presented.

SWICOM: An SDR-Based Wireless Communication Gateway for Vehicles

A wide range of emerging and promising wireless communication protocols are rapidly being introduced into vehicles. They are commonly used for in-car infotainment, telematics, and safety applications. However, adopting new wireless communications into vehicles requires them to be equipped with the corresponding hardware devices. This hardware dependency incurs extra costs to customers to deploy and maintain wireless services in vehicles. To alleviate this problem, this paper proposes a novel wireless communication gateway for vehicles that is called the software-defined radio (SDR)-based wireless communication gateway (SWICOM). It exploits the SDR technology that uses software running on a generic hardware platform to perform signal processing instead of dedicated hardware. The SWICOM can thus integrate multiple wireless hardware devices into a single generic wireless gateway device, which improves flexibility, adaptability, and connectivity of wireless communications. We built its prototype implementation and performed measurements to quantify its run-time performance. The worst-case execution time (WCET) analysis is also given using synchronous data flow (SDF) graphs. All entire results clearly show the viability of the SWICOM.

An SDR-Based Wireless Communication Gateway for Vehicle Networks

As telematics and infotainment services are becoming more and more prevalent on the roadway, modern vehicles need to be equipped to support various wireless communication standards. The conventional ways for implementing those standards are dependent on their dedicated hardware chips, and thus in order to add a new standard or change an obsolete standard, a new dedicated hardware chip should be installed. Software defined radio (SDR) technology enables software components running on a generic hardware platform to perform signal processing instead of hardware chips. Thus, it is possible to support multi-standard, multi-band and multi-mode solutions and easy to enhance and reconfigure wireless communication. In this paper, we propose an SDR-based wireless communication gateway for vehicle networks. It integrates multiple wireless devices into one single wireless gateway reducing maintenance costs of hardware chips and improving flexibility, adaptability and connectivity of wireless communication. In order to provide the proof of concept, we present its application to digital multimedia broadcasting service.