A novel mix-based location privacy mechanism in Mobile IPv6

Mobile IP (MIP), a link-layer-independent protocol, is suitable for Internet Protocol (IP) based mobility across homogeneous media as well as heterogeneous networks. Mobile IPv6 (MIPv6) not only possesses the major characteristics of Mobile IPv4 (MIPv4), but also has more advantages such as the expansion of address space and elimination of the “triangle routing”, which make MIPv6 the most suitable candidate for future heterogeneous environment. Location privacy is very important for mobile node (MN) in mobile communications because exposure of the relationship between MN's real physical location and its identity will lead to serious violation of the MN's privacy. And the attackers can easily launch the traffic analysis attack according to such revealed relationship. However, the location privacy of MN to avoid attackers tracing in MIP is not paid more attention up to the present. As the most widely used anonymous communication technology, mix-network can be used to provide the location privacy in MIP. In this paper, we employ the practical mix-network to provide location privacy on signaling control information in MIPv6. By utilizing the practical mix-network, a novel MIPv6 network model is proposed. Based on the network model, a new location privacy extension to MN's home binding and correspondent registration in MIPv6 is proposed and it can be integrated into MIPv6 easily. As a result, our location privacy proposal possesses the benefits succeeded from the adopted practical mix-network, e.g. reducing the trust requirements among the mix servers and increasing the robustness compared with other mix-based MIP location privacy schemes. In addition, the computation load in MN does not increase significantly during the binding procedures according to the analysis, thus it is more suitable for the asymmetric wireless environment.     

An efficient exact adjoint of the parallel MIT General Circulation Model, generated via automatic differentiation

We describe computational aspects of automatic differentiation applied to global ocean circulation modeling and state estimation. The task of minimizing a cost function measuring the ocean simulation versus observation misfit is achieved through efficient calculation of the cost gradient w.r.t. a set of controls via the adjoint technique. The adjoint code of the parallel MIT general circulation model is generated using TAMC or its successor TAF. To achieve a tractable problem in both CPU and memory requirements, in the light of control flow reversal, the adjoint code relies heavily on the balancing of storing versus recomputation via the checkpointing method. Further savings are achieved by exploiting self-adjointness of part of the computation. To retain scalability of domain decomposition-based parallelism, hand-written adjoint routines are provided. These complement routines of the parallel support package to perform corresponding operations in reverse mode. The unique feature of the TAF tool which enables the dumping of the adjoint state and restart the adjoint integration is exploited to overcome batch execution limitations on HPC machines for large-scale ocean and climate simulations. Strategies to test the correctness of the adjoint-generated gradient are presented. The size of a typical adjoint application is illustrated for the case of the global ocean state estimation problem undertaken by the SIO-JPL-MIT Consortium “Estimating the Circulation and Climate of the Ocean” (ECCO). Results are given by way of example.     

Sojourn time distribution in the M/M/1 queue with discriminatory processor-sharing

In this paper, we consider a queue with multiple K job classes, Poisson arrivals, exponentially distributed required service times in which a single processor serves according to the DPS discipline. More precisely, if there are n_i class i jobs in the system, i=1,…,K, each class j job receives a fraction _j/∑_i=1^K_in_i of the processor capacity. For this queue, we obtain a system of equations for joint transforms of the sojourn time and the number of jobs. Using this system of equations we find the moments of the sojourn time as a solution of linear simultaneous equations, which solves an open problem.     

SLA-based QoS pricing in DiffServ networks

The availability of high-speed transmission media and networking equipment in contemporary networks, as well as the evolution of quality-demanding applications has focused research interest on the provision of advanced qualitative services in addition to the traditional best-effort model of the Internet. A number of alternatives for service differentiation and QoS provisioning have been proposed and standardized, but in the case of backbone, transport networks the DiffServ architecture has prevailed, due to its scalability and deployment feasibility. The provisioning of services according to the DiffServ framework has in turn raised the requirements for interdependent, controlled resource allocation and service pricing, with particular needs for pricing mechanisms that preserve the potential and flexibility of DiffServ. At the same time, such mechanisms should reflect resource usage, allocate resources efficiently, reimburse costs or maximize service provision profits and lead customers to requesting services that will maximize their revenue. In this work, after reviewing related research, the principles that a pricing scheme for DiffServ-based services should follow are presented, stressing the differences form traditional Internet pricing. Based on these principles, an analytical approach to pricing a particular class of DiffServ-based services and a methodology for applying this approach in a real network are proposed and evaluated.     

Conceptual construction on incomplete survey data

The raw survey data for data mining are often incomplete. The issues of missing data in knowledge discovery are often ignored in data mining. This article presents the conceptual foundations of data mining with incomplete survey data, and proposes query processing for knowledge discovery and a set of query functions for the conceptual construction in survey data mining. Through a case, this paper demonstrates that conceptual construction on incomplete data can be accomplished by using artificial intelligence tools such as self-organizing maps.     

Analysis of link-level hybrid FEC/ARQ-SR for wireless links and long-lived TCP traffic

Since the TCP protocol uses the loss of packets as an indication of network congestion, its performance degrades over wireless links, which are characterized by a high bit error rate. Different solutions have been proposed to improve the performance of TCP over wireless links, the most promising one being the use of a hybrid model at the link level combining Forward Error Correction (FEC), Automatic Repeat Request with Selective Repeat (ARQ-SR), and an in-order delivery of packets to IP. The drawback of FEC is that it consumes some extra bandwidth to transmit the redundant information. ARQ-SR consumes extra bandwidth only when packets are lost, its drawback is that it increases the round-trip time (RTT), which may deteriorate the performance of TCP. Another drawback of ARQ-SR is that a complete packet can be retransmitted to correct a small piece of errored data. We study in this paper the performance of TCP over a wireless link implementing hybrid FEC/ARQ-SQ. The study is done by simulating and modeling long-lived TCP transfers over wireless links showing Bernoulli errors. We are motivated by how to tune link-level error recovery, e.g. amount of FEC, persistency of ARQ, so as to maximize the performance of TCP. We provide results for different physical characteristics of the wireless link (delay, error rate) and for different traffic loads (number of TCP connections).     

Image-based memory for robot navigation using properties of omnidirectional images

This paper proposes a new technique for vision-based robot navigation. The basic framework is to localise the robot by comparing images taken at its current location with reference images stored in its memory. In this work, the only sensor mounted on the robot is an omnidirectional camera. The Fourier components of the omnidirectional image provide a signature for the views acquired by the robot and can be used to simplify the solution to the robot navigation problem. The proposed system can calculate the robot position with variable accuracy (‘hierarchical localisation’) saving computational time when the robot does not need a precise localisation (e.g. when it is travelling through a clear space). In addition, the system is able to self-organise its visual memory of the environment. The self-organisation of visual memory is essential to realise a fully autonomous robot that is able to navigate in an unexplored environment. Experimental evidence of the robustness of this system is given in unmodified office environments.     

Link scheduling state information based offset management for fairness improvement in WDM optical burst switching networks

In wavelength division multiplexed (WDM)-based optical burst switching (OBS) networks, bursts that traverse longer paths are more likely to be dropped compared to bursts that traverse shorter paths resulting in a fairness problem. Fairness here refers to having, for all ingress–egress node pairs in a network, a burst to have equal likelihood to get through independent of the hop length involved. In this paper, we develop a link scheduling state based fairness improvement method which can be used in a classless as well as a multi-class environment. The basic idea is to collect link scheduling state information and use it to determine the offset times for routes with different hop lengths. By using the online link state information, this method periodically computes and adapts the offset times needed, thus inherently accounting for the traffic loading patterns and network topological connectivity. It also ensures that the delay experienced by a burst is low and shorter-hop bursts are not over-penalized while improving the performance of longer-hop bursts. The effectiveness of the proposed method is evaluated through simulation experiments.     

A configurable cryptography subsystem in a middleware framework for embedded systems

Computer and network security is becoming increasingly important as both large systems and, increasingly small, embedded systems are networked. Middleware frameworks aid the system developer who must interconnect individual systems into larger interconnected, distributed systems. However, there exist very few middleware frameworks that have been designed for use with embedded systems, which constitute the vast majority of CPUs produced each year, and none offer the range of security mechanisms required by the wide range of embedded system applications. This paper describes MicroQoSCORBA, a highly configurable middleware framework for embedded systems, and its security subsystem. It first presents an analysis of security requirements for embedded applications and what can and should be done in middleware. It then presents the design of MicroQoSCORBA’s security subsystem and the wide range of mechanisms it supports. Experimental results for these mechanisms are presented for two different embedded systems and one desktop computer that collectively represent a wide range of computational capabilities.