Chavalit Srisathapornphat

Sensor information networking architecture and applications

This article introduces a sensor information networking architecture, called SINA, that facilitates querying, monitoring, and tasking of sensor networks. SINA serves the role of middleware that abstracts a network of sensor nodes as a collection of massively distributed objects. SINAs execution environment provides a set of configuration and communication primitives that enable scalable and energy-efficient organization of and interactions among sensor objects. On top the execution environment is a programmable substrate that provides mechanisms to create associations and coordinate activities among sensor nodes. Users then access information within a sensor network using declarative queries, or perform tasks using programming script.

Topology control for ad hoc networks with directional antennas

Topology control for ad hoc networks aims to increase effective network capacity and conserve energy. Most proposed algorithms assume the use of isotropic antennas and thus only adjust the transmission power of each node. We propose a distributed topology control mechanism for ad hoc networks with directional antennas that adjusts antenna pattern (direction) in addition to transmission power. Simulation studies have been conducted to demonstrate the effectiveness of the approach, as well as to investigate its benefits and impacts on application layer performance.

CLTC: a cluster-based topology control for ad hoc networks

The topology of an ad hoc network has a significant impact on its performance in that a dense topology may induce high interference and low capacity, while a sparse topology is vulnerable to link failure and network partitioning. Topology control aims to maintain a topology that optimizes network performance while minimizing energy consumption. Existing topology control algorithms utilize either a purely centralized or a purely distributed approach. A centralized approach, although able to achieve strong connectivity (k-connectivity for k /spl ges/ 2), suffers from scalability problems. In contrast, a distributed approach, although scalable, lacks strong connectivity guarantees. We propose a hybrid topology control framework, cluster-based topology control (CLTC) that achieves both scalability and strong connectivity. By varying the algorithms utilized in each of the three phases of the framework, a variety of optimization objectives and topological properties can be achieved. In this paper, we present the CLTC framework; describe topology control algorithms based on CLTC and prove that k-connectivity is achieved using those algorithms; analyze the message complexity of an implementation of CLTC, namely, CLTC-A, and present simulation studies that evaluate the effectiveness of CLTC-A for a range of networks.

A busy-tone based directional MAC protocol for ad hoc networks

In mobile wireless ad hoc networking environments, such as the future combat system (FCS), the shared wireless communication medium is an inherently limited resource and is collision prone. In this paper, we propose to adapt the dual busy tone multiple access (DBTMA) protocol for use with directional antennas, which further increases effective channel capacity. In contrast to other directional antenna based MAC protocols, our protocol, termed DBTMA/DA, is capable of reserving channel capacity in finer grain without relying on extra locationing support. A simulation study is performed to demonstrate the better network performance of DBTMA/DA over DBTMA and the IEEE 802.11a MAC protocols.

Sensor Information Networking Architecture

The advent of technology has facilitated the development of networked systems of extremely small, low-power devices that combine programmable general-purpose computing with multiple sensing and wireless communication capability. This networked system of programmable sensor nodes, which together form a sensor network, poses unique challenges on how information collected by, and stored within, the sensor network could be queried and accessed, and how concurrent sensing tasks could be executed internally and programmed by external users. In this paper, we describe SINA (Sensor Information Networking Architecture), which facilitates the querying, monitoring and tasking of sensor networks. We model a sensor network as a collection of massively distributed objects, and SINA plays the role of middleware that facilitates the adaptive organization of sensor information. The SINA kernel provides a set of configuration and communication primitives that enable the scalable, robust and energy-efficient organization of, and interactions among, sensor objects. On top of the SINA kernel is a programmable substrate that follows the spreadsheet paradigm and provides mechanisms to create associations among sensor nodes. Users then access information within a sensor network using declarative queries and perform tasks using programmable scripts. Issues concerning interworking between stationary sensor networks and mobile nodes are also addressed.

Diagnosis of sensor networks

As sensor nodes are embedded into physical environments and becoming integral parts of our daily lives, sensor networks will become the important nerve systems that monitor and actuate our physical environments. We define the process of monitoring the status of a sensor network and figuring out the problematic sensor nodes sensor network diagnosis. However, the high sensor node-to-manager ratio makes it extremely difficult to pay special attention to any individual node. In addition, the response implosion problem, which occurs when a high volume of incoming replies triggered by diagnosis queries cause the central diagnosing node to become a bottleneck, is one major obstacle to be overcome. We describe approaches to addressing the response implosion problem in sensor network diagnosis. We also present simulation experiments on the performance of these approaches, and discuss presentation schemes for diagnostic results.

An adaptive management architecture for ad hoc networks

Ad hoc networks, where mobile nodes communicate via multihop wireless links, facilitate network connectivity without the aid of any preexisting networking infrastructure. The intrinsic attributes of ad hoc networks, such as dynamic network topology, limited battery power, constrained wireless bandwidth and quality, and large number of heterogeneous nodes, make network management significantly more challenging than stationary and wired networks. In particular, the conventional client/server-based manager/agent management paradigm falls short of addressing these issues. We describe the Guerrilla management architecture to facilitate adaptive and autonomous management of ad hoc networks. The management capability of Guerrilla is scalable to accommodate the sheer number and heterogeneity of nodes, autonomous and survivable to adapt to network dynamics, and economical to minimize management overhead.

Coordinated power conservation for ad hoc networks

Existing ad hoc routing protocols assume all nodes within the network to participate in the routing process. By conditionally selecting a subset of nodes is an appropriate approach to limiting the number of nodes participating in routing such that nodes not selected may be turned off to conserve power and extend network lifetime. However, not all non-routing-related nodes will be able to be turned off (suspended) at the same time. Sufficient bandwidth and forwarding capacity are still necessary in case of changing network topology and environment. We describe the coordinated power conservation (CPC) algorithm to facilitate power conservation for ad hoc networks. The algorithm constructs a backbone infrastructure to have CPC servers running on backbone nodes to coordinate suspending schedules among their local non-backbone nodes running CPC clients. Simulation results demonstrate that CPC-enabled ad hoc networks exhibit performance closely equivalent to ad hoc networks without CPC, while consuming less power.

The Guerrilla management architecture for ad hoc networks

Ad hoc networks, where mobile nodes communicate via multihop wireless links, facilitate network connectivity without the aid of any pre-existing networking infrastructure. The intrinsic attributes of ad hoc networks, such as dynamic network topology, limited battery supply, constrained wireless bandwidth and quality, and large number of heterogeneous nodes, make network management significantly more challenging than stationary and wireline networks. In particular, the conventional client/server-based manager-agent management paradigm falls short of addressing these issues. We describe the Guerrilla management architecture to facilitate adaptive and autonomous management of ad hoc networks and demonstrate its capability via simulation. Apart from its functionalities, the management capability itself is scalable to accommodate the sheer number and heterogeneity of nodes, autonomous and survivable to adapt to network dynamics, and economical to minimize management overhead.

Energy consumption behavior and performance of directional virtual carrier sensing schemes

Energy drainage from a node is mainly caused by the power consumption of the nodes communication device. A MAC protocol is the main mechanism to provide efficient access to the shared wireless channel. Directional antennas provide several benefits over several omnidirectional ones including the reduced energy consumption in frame transmissions. In this paper, we study and compare different generic directional virtual carrier sensing schemes (i.e., directional-RTS/CTS) in terms of their energy efficiency and performance. Both analytical and simulation results show that the schemes using directional-RTS and/or directional-CTS are more energy efficient than other schemes.