Distance Measures for Effective Clustering of ARIMA Time-Series

Many environmental and socioeconomic time--series data can be adequately modeled using Auto-Regressive Integrated Moving Average (ARIMA) models. We call such time--series ARIMA time--series. We consider the problem of clustering ARIMA time--series. We propose the use of the Linear Predictive Coding (LPC) cepstrum of time--series for clustering ARIMA time--series, by using the Euclidean distance between the LPC cepstra of two time--series as their dissimilarity measure. We demonstrate that LPC cepstral coefficients have the desired features for accurate clustering and efficient indexing of ARIMA time--series. For example, few LPC cepstral coefficients are sufficient in order to discriminate between time--series that are modeled by different ARIMA models. In fact this approach requires fewer coefficients than traditional approaches, such as DFT and DWT. The proposed distance measure can be used for measuring the similarity between different ARIMA models as well

Fast and Effective Wireless Handoff Scheme using Forwarding Pointers and Hierarchical Foreign Agents

Mobile IP, an extension of the standard IP protocol is used to keep track of location information and make the data available to the mobile device anytime, anywhere. With increasing technological developments in digital wireless transmission and location tracking devices, cell sizes are becoming smaller and smaller, increasing the available bandwidth per cell. Thus, the handoff latency between two cells is becoming an important aspect to minimize in order to maintain uniform connectivity. In standard Mobile IP, when the mobile host is far away from its home agent, the registration time delay is high. Hence, many data packets could get lost during the handoff. We propose a mobility management scheme that combines hierarchical mobility management with the forwarding pointer scheme. In this scheme, when a mobile host moves within a sub-net or within a domain, the registration requests are handled locally and not transmitted to the home agent. When a mobile host moves from one domain to another, forwarding pointers between the two domains are used to keep track of the location of the mobile host. This reduces handoff latency and location management cost. We present simulation results to validate our claim. I

Interaction of JVM with x86, Sparc and MIPS

A Java class is a perfect example of architecture independent code. A Java program can be compiled on a MIPS R4400 based Indy workstation running Irix 6.5 and the generated class executed on an Intel Pentium III based Windows 95 system with no problems. This independence is possible, because any system claiming to support Java implements a Java Virtual Machine (JVM). This paper presents a detailed analysis of the interaction of a JVM with three popular processor architectures – the Intel x86, the Sun UltraSparc and the SGI MIPS. The analysis shows that each architecture performs better than the other two in some aspects, but no one architecture is the “best ” for Java programs.