Jaewon Kang - Academia.edu (original) (raw)

Papers by Jaewon Kang

Sensor networks are being increasingly deployed for surveillance and monitoring applications. The... more Sensor networks are being increasingly deployed for surveillance and monitoring applications. These networks might suffer from severe congestion as soon as the target events are detected. Congestion control during this period is important not only to improve the overall throughput but also to lengthen the network lifetime by saving the scarce energy wasted due to congestion. While the traditional traffic control schemes that throttle the incoming traffic can effectively alleviate congestion, it does not increase the end-to-end throughput called accuracy level observed by the deployed application. In addition, throttling important data packets during this period can essentially nullify the purpose of sensor networks. In this thesis, I first attempt to formally define the resource control framework that adjusts the resource provisioning at the hotspot nodes. For accurate and timely congestion detection, I propose a new congestion detection mechanism that quantifies the congestion leve...

MILCOM 2013 - 2013 IEEE Military Communications Conference, 2013

The advances of Commercial cellular networks and smart devices over the last decade have changed ... more The advances of Commercial cellular networks and smart devices over the last decade have changed the way end users are communicating and connecting to each other. The soldiers in the battlefield are no exception and they would also like to have the similar experience as civilians have. Cellular networks are also providing significantly higher bandwidth at a much lower cost relative to tactical networks. However, these networks are not yet ready to be used as-is in military environment. Issues such as, frequency flexibility, operations in hostile environment, security, range extension, multicast, Push-to-Talk (PTT), and seamless session mobility that need to be addressed. Several efforts have started to look into the feasibility and deployability issues of commercial networks and devices so that they can be used as an extension to tactical networks. In recent years our focus have been addressing such issues and working closely with the US Army to fulfill the tactical requirements while hardening the technology. In this paper, we present a secure network architecture to the tactical edge that can leverage commercial cellular and ad hoc Wi-Fi networks as range extension and Android platform based smart devices fulfilling the tactical networking and security requirements. We describe our software design, implementation and recent demonstration at a Technology Readiness Levels (TRLs) - 4 and 5 in US Army Aberdeen Proving Ground, Maryland, and Fort Dix, NJ, USA.

Defense Transformation and Net-Centric Systems 2012, 2012

ABSTRACT To efficiently use alternate paths during periods of congestion, we have devised priorit... more ABSTRACT To efficiently use alternate paths during periods of congestion, we have devised prioritized Dynamic Routing Control Agent (pDRCA) that (1) selects best links to meet the bandwidth and delay requirements of traffic, (2) provides load-balancing and traffic prioritization when multiple topologies are available, and (3) handles changes in link quality and traffic demand, and link outages. pDRCA provides multiplatform load balancing to maximize SATCOM (both P2P and multi-point) and airborne links utilization. It influences link selection by configuring the cost metrics on a router's interface, which does not require any changes to the routing protocol itself. It supports service differentiation of multiple traffic priorities by providing more network resources to the highest priority flows. pDRCA does so by solving an optimization problem to find optimal links weights that increase throughput and decrease E2E delay; avoid congested, low quality, and long delay links; and exploit path diversity in the network. These optimal link weights are sent to the local agents to be configured on individual routers per traffic priority. The pDRCA optimization algorithm has been proven effective in improving application performance. We created a variety of different test scenarios by varying traffic profile and link behavior (stable links, varying capacity, and link outages). In the scenarios where high priority traffic experienced significant loss without pDRCA, the average loss was reduced from 49.5% to 13% and in some cases dropped to 0%. Currently, pDRCA is integrated with an open-source software router and priority queues on Linux as a component of Open Tactical Router (OTR), which is being developed by ONR DTCN program.

The speed gap between the processor and disks is becoming a serious problem in computer systems t... more The speed gap between the processor and disks is becoming a serious problem in computer systems today. To rectify this problem, various caching techniques have been traditionally used. For example, the UNIX operating system has a built-in cache called the buffer cache to keep recently used disk blocks in main memory. Another example is the so-called disk cache in I/O processors and intelligent disk controllers. These two types of cache form a two-level disk cache hierarchy where the buffer cache is the primary cache and the disk cache the secondary cache. In such a two-level cache hierarchy, unless special care is taken, it is likely that the disk blocks kept in one cache are also kept in the other cache resulting in reduced total caching capacity. In this paper, we describe the design and implementation of a unified cache management algorithm called the push-pull algorithm that tries to avoid such double caching. In the proposed algorithm, a new disk block is stored in only one cac...

2006 3rd Annual International Conference on Mobile and Ubiquitous Systems - Workshops, 2006

MILCOM 2015 - 2015 IEEE Military Communications Conference, 2015

Proceedings. 2004 12th IEEE International Conference on Networks (ICON 2004) (IEEE Cat. No.04EX955), 2000

GLOBECOM '03. IEEE Global Telecommunications Conference (IEEE Cat. No.03CH37489), 2000

Abstract As cellular packet data services become widely deployed by the rollout of the networks s... more Abstract As cellular packet data services become widely deployed by the rollout of the networks such as general packet radio service (GPRS) and 3G cellular networks, packet-switched voice service such as voice over IP (VoIP) can soon be expected to be offered as ...

Computer Communications, May 1, 2006

... Then the voice traffic from the mobile station continues to be forwarded to the PSTN phone th... more ... Then the voice traffic from the mobile station continues to be forwarded to the PSTN phone through the ... at the mobile station from the media gateway when restoring the VoIP call, the RTP packets generated at the media gateway can be buffered at the base station instead of ...

Wireless Networks, Apr 30, 2009

2004 IEEE 59th Vehicular Technology Conference. VTC 2004-Spring (IEEE Cat. No.04CH37514), 2004

Abstract In this paper, unlike the current end-to-end congestion control mechanism such as TCP th... more Abstract In this paper, unlike the current end-to-end congestion control mechanism such as TCP that only reduces its traffic in the presence of congestion, we propose a new wireless congestion control framework, in which a mobile station's MAC-layer tries to increase its ...

2009 IEEE International Conference on Communications, 2009

11th IEEE Symposium on Computers and Communications (ISCC'06), 2006

IEEE Wireless Communications and Networking Conference, 2005, 2005

Abstract Congestion in ad hoc networks not only degrades throughput, but also wastes scarce energ... more Abstract Congestion in ad hoc networks not only degrades throughput, but also wastes scarce energy due to a large number of retransmissions and packet drops. For efficient congestion control, an accurate and timely estimation of resource demands by measuring ...

Lecture Notes in Computer Science, 2004