Optimal Drive-by Sensing in Urban Road Networks with Large-scale Ridesourcing Vehicles

The sensing and monitoring of the urban road network contribute to the efficient operation of the urban transportation system and the functionality of urban systems. However, traditional sensing methods, such as inductive loop sensors, roadside cameras, and crowdsourcing data from massive urban travelers (e.g., Google Maps), are often hindered by high costs, limited coverage, and low reliability. This study explores the potential of drive-by sensing, an innovative approach that employs large-scale ridesourcing vehicles (RVs) for urban road network monitoring. We first evaluate RV sensing performance by coverage and reliability through historical road segment visits. Next, we propose an optimal trip-based RV rerouting model to maximize the sensing coverage and reliability while preserving the same level of service for the RVs' mobility service. Furthermore, a scalable column generation-based heuristic is designed to guide the cruising trajectory of RVs, assuming trip independence. The effectiveness of the proposed model is validated through experiments and sensitivity analyses using real-world RV trajectory data of over 20,000 vehicles in New York City. The optimized rerouting strategy has yielded significantly improved results, elevating explicit sensing coverage of the road network by 15.0\% to 17.3\% (varies by time of day) and achieving an impressive enhancement in sensing reliability by at least 24.6\% compared to historical records. Expanding the path-searching space further improved sensing coverage of up to 4.5\% and reliability of over 4.2\%. Moreover, considering incentives for RV drivers, the enhanced sensing performance comes at a remarkably low cost of \$0.10 per RV driver, highlighting its cost-effectiveness

Multi-layer survivability in IP-over-WDM networks

Ph.DDOCTOR OF PHILOSOPH

A two-step approach to restorable dynamic QoS routing

Aiming at minimizing the combined bandwidth cost of a pair of disjoint active and backup paths, a popular approach to designing Restorable Dynamic QoS Routing schemes is based on Integer Linear Programming (ILP) formulation. Owing to the very different natures of active and backup paths, we found this approach problematic. In this paper, we propose a simple alternative approach, called two-step routing. In the first step, active path is found using the widest-shortest path (WSP) routing. In the second step, the corresponding backup path is determined using one of the three variants of shortest-widest path (SWP) routing, Basic-SWP, Approximate-SWP and Composite-SWP. Combining both steps, three novel restorable routing algorithms, SBW, SAW and SCW, are obtained. Comparing with the existing best-known algorithms, we show that our two-step routing approach yields noticeably lower call blocking probability, shorter active path length, and adjustable backup path length (depending on the SWP variant adopted). Besides, our two-step routing approach gives a much shorter running time than the ILP approach, which makes it more attractive for dynamic routing.published_or_final_versio

Hardware Trojan Detection and Mitigation in NoC using Key authentication and Obfuscation Techniques

Today's Multiprocessor System-on-Chip (MPSoC) contains many cores and integrated circuits. Due to the current requirements of communication, we make use of Network-on-Chip (NoC) to obtain high throughput and low latency. NoC is a communication architecture used in the processor cores to transfer  data from source to destination through several nodes. Since NoC deals with on-chip interconnection for data transmission, it will be a good prey for data leakage and other security attacks. One such way of attacking is done by a third-party vendor introducing Hardware Trojans (HTs) into routers of NoC architecture. This can cause packets to traverse in wrong paths, leak/extract information and cause Denial-of-Service (DoS) degrading the system performance. In this paper, a novel HT detection and mitigation approach using obfuscation and key-based authentication technique is proposed. The proposed technique prevents any illegal transitions between routers thereby protecting data from malicious activities, such as packet misrouting and information leakage. The proposed technique is evaluated on a 4x4 NoC architecture under synthetic traffic pattern and benchmarks, the hardware model is synthesized in Cadence Tool with 90nm technology. The introduced Hardware Trojan affects 8% of packets passing through infected router. Experimental results demonstrate that the proposed technique prevents those 10-15% of packets infected from the HT effect. Our proposed work has negligible power and area overhead of 8.6% and  2% respectively

Fault Tolerant Rerouting in Broadband Multiclass Networks

Modern broadband integrated service digital networks (B-ISDN) must handle multiclass traffic with diverse quality of service (QOS) requirements. The main purpose of our research is to design call rerouting mechanisms which provide rapid restoration of network services in case of link failures. We suggest two approaches: Virtual circuit (VC) and virtual path (VP) reroutings. The first approach is more reactive while the latter is more proactive. The applicability conditions for the first approach include the availability of a layered network structure similar to VC/VP architecture which is widely accepted in asynchronous transfer mode (ATM) networks. Another applicability condition is the extent of network failure: VP level restoration is designed for single link failures - the most common in the telecommunication networks. On the other hand, in case of less predictable multiple link failures, VC-level rerouting is appropriate. These two rerouting approaches vary in the amount of time required to carry them out. Though both schemes are designed to work in real time, VP-level rerouting tends to be faster and can be performed in an on-line mode using pre-computed paths. VC- level rerouting requires real-time computation of routes which may result in a noticeable impact on some services. On the other hand, VP-level rerouting requires a substantial amount of off- line computation to design the VP layout and the backup routes.In this dissertation we propose a new model and associated algorithms to solve a VC-rerouting problem in real time. This model takes advantage of the distributed network data and computational resources by decomposing the problem at an early stage and then performing the computations in a decentralized mode.In order to solve the fault tolerant VP layout problem, we formulate a bi-criteria optimization model reflecting the tradeoff between throughput and certain QOS requirements. The model involves a piece-wise linear approximation to the capacity allocation rule for variable bit rate connections statistically multiplexed over a VP.Both models are formulated as integer programs. The solution method developed employ relaxation and aggregation of variables, feasible solution heuristics and valid inequalities. The results of the computational experiments presented indicate that the methods developed are efficient and produce accurate solutions

MPLS & QoS in Virtual Environments

The rise of high performance computing has seen a shift of services from locally managed Data Centers, to centralized globally redundant Data Centers (Cloud Computing). The scale of operation and churn required for cloud computing has in turn led to the rise of faster and programmable network pathing, via SDN & NFV. Cloud compute resources are accessible to individual researchers, as well as larger organizations. Cloud computing relies heavily on virtualization and abstraction of resources. The interconnect between these resources is more complex than ever, due to the need to seamlessly move from virtual to physical to hybrid networks and resources. MPLS as a technology is robust and has been used as transport for decades with a good track record. QoS has been available within most protocols to ensure service levels are maintained. The integration of MPLS, QoS and virtual environments is a space of increasing interest. It would allow for the seamless movement of traffic from end to end without the need for specialized hardware or vendor lock-in. In this thesis, the performance gains of IP/MPLS networks utilizing QoS on commercially available virtual environments has been investigated and studied. Latency was captured via round trip time metrics and tabulated for voice, video and data, with QoS and congestion as the primary differentiators. The study discusses the approach taken, the common thinking, and finally analyzes the results of a simulation, in order to show that MPLS & QoS benefits are viable in virtualized environments