Agustinus Borgy Waluyo

A Novel Structure and Access Mechanism for Mobile Data Broadcast in Digital Ecosystems

Digital ecosystems offer cost-effective digital services that attract and benefit the species within them (i.e., humans, organizations, and computers). As a cornerstone technology for digital information delivery, data broadcast provides a strong backbone for the digital ecosystem infrastructure. Its scalability feature is highly significant for various digital ecosystem applications, including mobile broadcast services. This paper proposes a novel structure and access for mobile data broadcast. The proposed scheme addresses the tradeoff for minimizing query-access and tuning times by specifying a new message structure. Correspondingly, a new access and processing mode for mobile clients is required. We study the effectiveness of the proposed approach in minimizing query-access time while maintaining low tuning time. The results of our experiments are used to make comparisons with existing approaches. The results affirm the effectiveness of our proposed scheme.

Trustworthy-based efficient data broadcast model for P2P interaction in resource-constrained wireless environments

In a decentralised system like P2P where each individual peers are considerably autonomous, the notion of mutual trust between peers is critical. In addition, when the environment is subject to inherent resource constraints, any efficiency efforts are essentially needed. In light of these two issues, we propose a novel trustworthy-based efficient broadcast scheme in a resource-constrained P2P environment. The trustworthiness is associated with the peer@?s reputation. A peer holds a personalised view of reputation towards other peers in four categories namely SpEed, Correctness, qUality, and Risk-freE (SeCuRE). The value of each category constitutes a fraction of the reliability of individual peer. Another factor that contributes to the reliability of a peer is the peer@?s credibility concerning trustworthiness in providing recommendation about other peers. Our trust management scheme is applied in conjunction with our trust model in order to detect malicious and collaborative-based malicious peers. Knowledge of trustworthiness among peers is used in our proposed broadcast model named trustworthy-based estafet multi-point relays (TEMPR). This model is designed to minimise the communication overhead between peers while considering the trustworthiness of the peers such that only trustworthy peer may relay messages to other peers. With our approach, each peer is able to disseminate messages in the most efficient and reliable manner.

Optimal Broadcast Channel for Data Dissemination in Mobile Database Environment

The increase number of mobile users in wireless environment affects query access time substantially. To minimise the query access time, one possible way is to employ data broadcasting strategy. In this paper, we propose cost models for both query access time over broadcast channel and on-demand channel. We examine the cost models to find optimum number of broadcast items in a channel while utilising query access time over on-demand channel as a threshold point. The optimum number indicates a point to split the broadcast cycle and allocate the data items in the new channel or else the on-demand channel outperforms the broadcast channel. The cost model involves several factors that dynamically change the optimum number of broadcast items like request arrival rate, service rate, size of data item, size of request, and bandwidth. Simulation model is developed to verify the performance of the cost model. This paper focuses on request that returns a single data item.

A taxonomy of broadcast indexing schemes for multi channel data dissemination in mobile databases

Data broadcasting strategy is known as a scalable way to disseminate information to mobile users. However, with a very large set of broadcast items, the query access time of mobile clients raise accordingly, due to high waiting time for mobile clients to find their data of interest. One possible solution is to split the database information into several broadcast channels. In this paper, we introduce taxonomy of index dissemination for multibroadcast channel based on B* tree structure. We consider three indexing schemes namely: (i) nonreplicated indexing scheme (NRI), (ii) partially-replicated indexing scheme (PRI), and (iii) fully-replicated indexing scheme (FRI). Simulation model is developed to find out the access time performance of each scheme.

A pure peer-to-peer approach for kNN query processing in mobile ad hoc networks

Together with advanced positioning and mobile technologies, P2P query processing has attracted a growing interest number of location-aware applications such as answering kNN queries in mobile ad hoc networks. It not only overcomes drawbacks of centralized systems, for example single point of failure and bottleneck issues, but more importantly harnesses power of peers’ collaboration. In this research, we propose a pure mobile P2P query processing scheme which primarily focuses on the search and validation algorithm for kNN queries. The proposed scheme is designed for pure mobile P2P environments with the absence of the base station support. Compared with centralized and hybrid systems, our system can reduce energy consumption more than six times by making use of data sharing from peers in a reasonable mean latency of processing time for networks with high density of moving objects as can be seen in the simulation results.

Mobile Peer-to-Peer data dissemination in wireless ad-hoc networks

This paper introduces token-passing based multi-point relays (TOSS) data dissemination scheme in mobile Peer-to-Peer (P2P) environments. TOSS is designed to support reliability and efficiency of the peers to disseminate messages to other peers in mobile P2P networks. The TOSS model incorporates location-based scheduling technique as a means to determine the most optimal scheduling for the peers to receive messages whilst taking into account the location and mobility of the peers. The novelties of this paper are summarized as follows; (i) it presents an efficient scheduling approach to disseminate messages; (ii) it formulates location-based scheduling schemes for constructing the order of the delivery; (iii) it experimentally evaluates the performance of the proposed approach and compares them against the most closely relevant prior arts (e.g. pure flooding and Trustworthiness -based Broadcast (TBB) scheme) in respect to the transmission cost, computational cost and message deliverable performance. The experiments yield a promising result for TOSS based on the metrics of studies.

Global indexing scheme for location-dependent queries in multi channels mobile broadcast environment

Broadcast indexing is necessary to be applied in a wireless broadcast environment as such the scheme helps mobile clients to find the desired data instances efficiently. This is particularly important considering the inherent limitations in mobile environment. In this paper, we present a global indexing scheme for location dependent queries. The proposed scheme is designed to serve queries in which the query result is relevant to clients location. Global indexing scheme aims to minimise index access time while having all the advantages of index broadcasting. We develop a simulation model to find out the access time performance of global indexing scheme as compared to non-global indexing scheme. Additionally, we analyse the efficiency of valid scope used in the global index scheme as compared with an existing valid scope. It is found that global index performs substantially better than the existing indexing concept.

Real-time tracking of flexion angle by using wearable accelerometer sensors

This paper presents a new algorithm for real time tracking the flexion angle from wearable accelerometer sensor data using wireless body sensor network (BSN). The proposed algorithm uses dynamic filter for tracking the flexion angles of which the human body dynamics is described by its system model. In this work, the Extended Kalman Filtering is used to demonstrate the superiority of this approach. Results from a thigh tracking experiment show that the flexion angle estimated closely followed that of the video data.

Middleware for Wireless Medical Body Area Network

Advances in wireless sensor technology have opened up a new paradigm in the healthcare industry. Ubiquitous and embedded medical monitoring is no longer a myth and this helps improve the daily lives of the sick, elderly, infirm, and chronically ill people. Given the variety of medical body sensors and its applications, it is definitely of interest to implement a middleware system that shield off these differences from the application layer. The aim of this paper is to propose such middleware for wireless medical body area network. The proposed middleware has the ability to support: (i) multiple sensors and applications, (ii) plug and play feature, and (iii) resource management. The middleware has been implemented and the prototype system has been built. The effective uses of the proposed middleware will be shown with the healthcare monitoring system running on top of the middleware.

Global Index for Multi Channel Data Dissemination in Mobile Databases

Data broadcasting strategy is known as a scalable way to disseminate information to mobile users. However, with a very large number of broadcast items, the access time of mobile clients increase accordingly, due to high waiting time for mobile clients to find their data of interest. One possible solution is to split the database information into several broadcast channels. In this paper, we introduce global indexing technique for multi broadcast channels. A simulation model is developed to find out the performance of the technique.