Mira Yun

Channel-Assignment and Scheduling in Wireless Mesh Networks Considering Switching Overhead

This paper considers the channel-assignment and scheduling in wireless mesh networks that employ multiple radios and multiple channels. In contrast to the various algorithms available in the literature, we explicitly model the delay overhead that is incurred during channel switching, and use that delay in the design of algorithms. We prove that the well known Greedy Maximal Scheduling (GMS) algorithm does not have any provable efficiency ratio when the switching overhead is considered. We present a centralized algorithm (CGSSO), and a dynamic algorithm (DMSSO), both of which consider switching overhead. Simulation results show that the proposed algorithms significantly outperform other algorithms in packet throughput and average packet delay metrics. Results also show that the improvements in performance become more pronounced as the switching delay increases.

Scheduling Algorithms For Policy Driven QoS Support in HSDPA Networks

Increasing demand for high data-rate multimedia services has led to the emergence of high-speed data transfer features such as high-speed downlink packet access (HSDPA) for WCDMA networks. The role of the MAC-hs scheduler is vital in HSDPA in improving overall system performance. Using opportunistic scheduling to exploit multi-user diversity for efficient transmission of best effort services or considering user fairness constraints has been the main focus of most scheduling algorithms. However the need for strict QoS support for services such as streaming, gaming, and VoIP is growing. Service operators can enforce their own policies in meeting these QoS requirements. In this paper we introduce two QoS-aware policy driven scheduling algorithms. We developed an HSDPA system in OPNET, and implemented our scheduling algorithms along with other well-known algorithms. OPNET simulations show that unlike other schedulers, our strict and loose policy scheduling (SPS and LPS) algorithms comply with the policy constraints if allowed by radio conditions and cell capacity.

Battle event detection using sensor networks and distributed query processing

We consider the problem of identifying battlefield events using sensors deployed in the area. The goal is to alert centralized headquarters about the occurrence of significant events so that it can respond appropriately to the events. We propose a mechanism using which the sensors can exchange information using signatures of events instead of data to save on transmission costs. Further, we propose an algorithm that dynamically generates phases of information exchange based on the cost and selectivity of each filter.We present simulation results that compare the proposed algorithm to other alternatives. Our results show that the proposed algorithm detects events while minimizing the transmission and processing costs at sensors.

RL-Based Queue Management for QoS Support in Multi-channel Multi-radio Mesh Networks

In this paper, we consider the important aspect of Quality of Service (QoS) in Wireless Mesh Networks, focusing on packet delays and packet drops. We observe that the options of solely focusing on throughput, and of only depending on the QoS type characterization by the application level protocol is not sufficient. We propose the use of multiple queues to hold the packets based on their QoS requirement (not necessarily corresponding to the QoS application types). We suggest the technique of reinforcement learning (RL) for the important step of assigning packet to one of the queues, and present an implementation using the TD(0) algorithm. We present various simulation results comparing our algorithm to other known algorithms and frameworks. Our results indicate that our RL-based algorithm is significantly better than previously known results in packet drop ratio.

Automated Ride Share Selection Using Vehicular Area Networks

This paper considers the possible application of ride share services in Vehicular Area Networks. We propose a system architecture and protocol for this specific application using the Vehicle to Vehicle (V2V) and Vehicle to Road (V2R) communications. We present how the system would integrate with the current VANET infrastructure and the On-Board Unit, and present algorithms for selection of ride share options. We also present simulation scenarios and theoretical analysis of the likelihood of finding an acceptable ride share option using the proposed system, and analyze the expected network overhead caused by the system. Index Terms—vehicular networks, intelligent vehicles, ride share, carpool

Analysis of Uplink Traffic Characteristics and Impact on Performance in Mobile Data Networks

User-generated content (UGC) also known as user- created content (UCC) refers to various kinds of media contents that are produced by end users. A recent trend in the use of the Internet exhibits that data traffic from UGC is rapidly growing with the potential to create a huge amount of uplink traffic for wireless operators. As the reality of UGCs scope and power is becoming crystalized, modeling and analysis of uplink traffic has just begun to receive growing attention in the wireless community. Consequently, we have also analyzed live uplink traffic traces obtained by monitoring 3G networks of a mobile data service provider (SK Telecom in Korea). Our statistical analysis shows the self-similarity in this traffic trace. In order to evaluate the impact of this characteristics on mobile data networks, we use the WiMAX module available in OPNET software. Our trace-driven simulation results indicate burstiness in the aggregated traffic received at a base station (BS) as well as in the traffic generated at each subscriber station (SS). The impact of the data burst at SSs is shown to be negligible when the overall traffic load is relatively small but become significant when a large volume of delay-sensitive traffic is generated in many SSs even if the overall network load is less than the network capacity.

Design for Run-Time Monitor on Cloud Computing

Cloud computing is a new information technology trend that moves computing and data away from desktops and portable PCs into large data centers. The basic principle of cloud computing is to deliver applications as services over the Internet as well as infrastructure. A cloud is the type of a parallel and distributed system consisting of a collection of inter-connected and virtualized computers that are dynamically provisioned and presented as one or more unified computing resources. The large-scale distributed applications on a cloud require adaptive service-based software, which has the capability of monitoring the system status change, analyzing the monitored information, and adapting its service configuration while considering tradeoffs among multiple QoS features simultaneously. In this paper, we design Run-Time Monitor (RTM) which is a system software to monitor the application behavior at run-time, analyze the collected information, and optimize resources on cloud computing. RTM monitors application software through library instrumentation as well as underlying hardware through performance counter optimizing its computing configuration based on the analyzed data.

Fault/attack tolerant recovery mechanism under SRLG constraint in the next generation optical VPN

A “Virtual Private Network (VPN) over Internet” has the benefits of being cost-effective and flexible. However, given the increasing demands for high bandwidth Internet and for reliable services in a “VPN over Internet,” an IP/GMPLS over DWDM backbone network is regarded as a very favorable approach for the future “Optical VPN (OVPN)” due to the benefits of transparency and high data rate. Nevertheless, OVPN still has survivability issues such that a temporary fault can lose a large amount of data in seconds, moreover unauthorized physical attack can also be made on purpose to eavesdrop the network through physical components. Therefore fault/attack tolerant recovery mechanism that considers physical components is needed because optical network has vulnerabilities involved in the intrinsic characteristics, and these characteristics possibly menace reliable services in OVPN. Thus in this paper, with considering fault/attack in the next generation OVPN, we propose a recovery mechanism under shared risk link group (SRLG) constraint for network survivability by means of the classification of optical components and shared risk levels.

Uplink Resource Management Design in Multi-access Wireless Networks

In this paper, we develop a new uplink resource management scheme in heterogeneous networking environments that support multiple radio access technologies (RATs). A common radio resource management (CRRM) model is utilized to handle uplink traffic in multi-access radio networks. To evaluate the effect and performance of CRRM, a simulation study is conducted on scenarios where different scheduling algorithms are applied with and without vertical handoffs through the aid of CRRM.

Smart guide: mid-scale NFC navigation system

Existing navigation systems that utilize GPS are unreliable on any smaller scales ventures such as on or within a campus and generally are unstable within buildings or other structures. We found a need to have a more reliable way to access directions when GPS systems were inaccurate or inaccessible. Since NFC readers are not uncommon in mobile phones nowadays, we propose a new portable system, Smart Guide, to utilize this underused technology in a new way. In this paper, we present Smart Guide that is an Android application using NFC to aid a user in mid-scale navigation.