Joo Ghee Lim

Learn More
In an ad hoc sensor network clock synchronization is a serious issue as nodes in the sensor network have different clock drifts. One of the common solutions for the time synchronization among these nodes is the active transmission of time stamp messages. However this method consumes some resources and channel bandwidth, and is not suitable for resource(More)
— Localization schemes using hop-counts to reference nodes of known positions have been proposed to localize nodes in a sensor network. However, these schemes usually work well only when the networks have uniform and dense node distribution. In view of this, a novel Density-aware Hop-count Localization (DHL) algorithm is described here to improve the(More)
We address the problem of minimizing the worst-case broadcast delay in " multi-radio multi-channel multi-rate wireless mesh networks " (MR 2-MC WMN) in a distributed and localized fashion. Efficient broadcasting in such networks is especially challenging due to the desirability of exploiting the " wireless broadcast advantage " (WBA), the(More)
We address the problem of minimizing the worst-case broadcast delay in multi-rate wireless mesh networks (WMN) in a distributed and localized fashion. Efficient broadcasting in such networks is especially challenging due to the multi-rate transmission capability and the interference between wireless transmissions of WMN nodes. We propose connecting(More)
As more wireless networks are being deployed in a given geographic area, the problem of interference and coexistence of these independently operated networks is becoming an increasing problem. This paper looks at the coexistence of independent multihop Wireless Mesh Networks (WMNs). We argue that cooperation is difficult in such scenarios. We define a(More)
Amidst the numerous active research efforts in wireless sensor networks which aim to push beyond the limits, we aim to significantly enhance the effectiveness of wireless sensors by integrating controlled mobility to realize a networked system of mobile sensors that functions collectively as an integrated unit. The All-teRrain Advanced NeTwork of Ubiquitous(More)
— A Wireless Mesh Network (WMN) that utilizes multiple interfaces and multiple channels has been shown to improve network performance by reducing the interference and increasing the available bandwidth. However, the contention delay experienced by a frame along every hop of the WMN can still limit the performance. In addition, cross-layer delay occurs when(More)
– Simple algorithms have been developed in the area of node localization in a wireless sensor network. For these simple algorithms to work, several assumptions were made. However, the accuracy of such assumptions affects the effectiveness and performance of such algorithms. For example, the irregular propagation pattern of transmission range is often(More)