Kideok Cho, Hakyung Jung, Munyoung Lee, Diko Ko, Ted "Taekyoung" Kwon, and Yanghee Choi, "How can an ISP merge with a CDN?," IEEE Communications Magazine, Vol. 49, No. 10, pp. 156-162, October. 2011.
As delivering contents has become the dominant usage of the Internet, efficient content distribution is one of the hottest research areas in the network community. In future networks, it is anticipated that network entities such as routers will be equipped with in-network storage due to the trend of ever decreasing storage cost. In this article, we propose a novel content delivery architecture called ISP-centric content delivery (iCODE) by which an ISP can provide content delivery services as well. iCODE can provide efficient content delivery services since an ISP can cache contents in routers with storage modules considering traffic engineering and the locality of the content requests. Compared to CDN and P2P systems, iCODE can offer reduced delivery latency by placing the contents closer to end hosts, and incentives to ISPs by reducing inter- ISP traffic and allowing traffic engineering. We also discuss the technical and business issues to realize the iCODE architecture.
@ARTICLE{6035830,
author={Cho, K. and Jung, H. and Lee, M. and Ko, D. and Kwon, T.??. and Choi, Y.},
journal={Communications Magazine, IEEE}, title={How can an ISP merge with a CDN?},
year={2011},
month={oct. },
volume={49},
number={10},
pages={156 -162},
keywords={},
doi={10.1109/MCOM.2011.6035830},
ISSN={0163-6804},}
- Hakyung Jung, Ted "Taekyoung" Kwon, Kideok Cho, and Yanghee Choi, "REACT: Rate Adaptation using Coherence Time in 802.11 WLANs," Elsevier Computer Communications, Vol. 34, No. 11, pp. 1316-1327, July 2011.
The channel coherence time in indoor WLANs normally exceeds multiple frame transmission times. In light of this, we propose a new rate adaptation scheme, termed as the Rate Adaptation using Coherence Time (REACT), that has the following key features. First, without exchanging RTS and CTS frames, the receiver in REACT informs the transmitter of the improved channel condition via altering the ACK transmission rate, so that the transmitter increases the data rate for subsequent data frames. This enables the transmitter to adapt to the time-varying channel conditions while inducing the marginal overhead. Second, the transmitter in REACT can identify the reasons of frame losses by exploiting the feedback from the receiver and the estimated coherence time. Frame losses are assumed to be caused only by collisions for the duration of the coherence time after receiving an ACK frame with the altered bit rate. The coherence time is also used to enhance the adaptive RTS probing, so that the REACT can prevent the transmitter from decreasing its bit rate when collisions occur. Extensive simulations reveal that REACT consistently performs better than the other rate adaptation schemes (ARF, CARA, RRAA, and RBAR) in all the testing scenarios.
@article{Jung2011,
title = "REACT: Rate Adaptation using Coherence Time in 802.11 WLANs",
journal = "Computer Communications",
volume = "34",
number = "11",
pages = "1316 - 1327",
year = "2011",
note = "",
issn = "0140-3664",
doi = "DOI: 10.1016/j.comcom.2011.01.011",
url = "http://www.sciencedirect.com/science/article/pii/S0140366411000594",
author = "Hakyung Jung and Ted "Taekyoung" Kwon and Kideok Cho and Yanghee Choi",
keywords = "Wireless LAN",
keywords = "Rate adaptation",
keywords = "Multi-rate",
keywords = "802.11",
keywords = "Coherence time"
}
- Kideok Cho, Hakyung Jung, Munyoung Lee, Diko Ko, Ted "Taekyoung" Kwon, and Yanghee Choi, "How can an ISP merge with a CDN?," in Proc. ITU Kaleidoscope - Beyond the Internet? - Innovations for future networks and services, the best paper award (2nd place), Pune, India, December 2010.
As delivering contents has become the dominant usage of Internet, the effcient content distribution is being one of the hottest research areas in network community. In future network, it is anticipated that network entities such as routers will be equipped with in-network storage due to the trend of ever-decreasing storage cost. In this paper, we propose a novel content delivery architecture called Internet Service Provider (ISP) centric Content Delivery (iCODE) by which an ISP can provide content delivery services as well. iCODE can provide efficient content delivery services since an ISP can cache the contents in routers with storage modules considering traffic engineering and the locality of the content requests. Compared with CDN and P2P systems, iCODE can offer reduced delivery latency by placing the contents closer to end hosts, and incentives to ISPs by reducing interISP traffic and allowing traffic engineering. We also discuss the technical and business issues to realize the iCODE architecture.
@INPROCEEDINGS{5682140,
author={Kideok Cho and Hakyung Jung and Munyoung Lee and Diko Ko and Kwon, T.T. and Yanghee Choi},
booktitle={Kaleidoscope: Beyond the Internet? - Innovations for Future Networks and Services, 2010 ITU-T}, title={How can an ISP merge with a CDN?},
year={2010},
month=dec.,
volume={},
number={},
pages={1 -7},
keywords={ISP traffic engineering;Internet service provider;content delivery network;iCODE architecture;Internet;telecommunication network management;},
doi={},
ISSN={},}
- Youngbin Im, Hakyung Jung, Ji Hoon Lee, Wonjun Yoon, Ted "Taekyoung" Kwon, Yanghee Choi, "Vertical Handovers in Multiple Heterogeneous Wireless Networks: A Measurement Study for the Future Internet," in Proc. International Conference on Future Internet Technologies (CFI) 2010, Seoul, Korea, June 2010.
As the access patterns of mobile users are diverse and their traffc demand is growing, multiple wireless access networks become dominant and their coexistence will be the norm in the future Internet infrastructure. To evaluate protocols and algorithms in these heterogeneous wireless networking environments, testbed-based experiments are of crucial importance since mathematical modeling and simulation can- not reflect the high complexity of systems and wireless link dynamics suffciently. Leveraging femtocell technologies, we propose and build a testbed in which WiFi access points and WiMAX base stations are integrated. We also imple- ment the vertical handover functionality through the SIP protocol, and carry out comprehensive measurements to analyze vertical handover delays. The testbed measurements of vertical handovers reveal that the DHCP mechanism, the authentication process in WiMAX, and the probing process in WiFi incur substantial delay.
@inproceedings{Im:2010:VHM:1853079.1853083,
author = {Im, Youngbin and Jung, Hakyung and Lee, Ji Hoon and Yoon, Wonjun and Kwon, Ted "Taekyoung" and Choi, Yanghee},
title = {Vertical handovers in multiple heterogeneous wireless networks: a measurement study for the future internet},
booktitle = {Proceedings of the 5th International Conference on Future Internet Technologies},
series = {CFI '10},
year = {2010},
isbn = {978-1-4503-0230-2},
location = {Seoul, Korea},
pages = {10--13},
numpages = {4},
url = {http://doi.acm.org/10.1145/1853079.1853083},
doi = {http://doi.acm.org/10.1145/1853079.1853083},
acmid = {1853083},
publisher = {ACM},
address = {New York, NY, USA},
keywords = {WiFi, WiMAX, femtocell, heterogeneous wireless network, vertical handover, wireless testbed}, }
- Hakyung Jung, Bruno Tuffin, "Pricing for Heterogeneous Services in OFDMA 802.16 Systems," in Proc. International Conference on Wireless On-demand Network Systems and Services (WONS) 2009, Snowbird, Utah, USA, Feburary 2009.
The IEEE 802.16 standard is expected to become a successful broadband wireless access solution, especially thanks to its ablility to provide high data rates, to differentiate services, and thanks to its interoperability, as promoted by the Worldwide Interoperability for Microwave Access (WiMAX) organization. We consider in this paper an Orthogonal Frequency Division Multiple Access (OFDMA)-based 802.16 operator, and investigate how to charge in order to control demand and maximize the revenue. Pricing has indeed been seen as a way to provide return on investment for providers, as well as to control demand and differentiate services for delivering a satisfactory quality of service (QoS) to heterogeneous applications. Our model specifically assumes two classes of applications with an infinite population of potential customers. The average number of customers per class is naturally regulated by prices but also the resulting QoS, this QoS depending itself on the customers in each class. We analyze the equilibrium situation of this game for fixed prices, and then numerically determine prices maximizing the operator's revenue.
@INPROCEEDINGS{4801833,
author={Hakyung Jung and Tuffin, B.},
booktitle={Wireless On-Demand Network Systems and Services, 2009. WONS 2009. Sixth International Conference on}, title={Pricing for heterogeneous services in OFDMA 802.16 systems},
year={2009},
month=feb.,
volume={},
number={},
pages={49 -52},
keywords={IEEE 802.16 standard;OFDMA;OFDMA 802.16;QoS;WiMAX;frequency division multiple access;heterogeneous services;pricing;quality of service;worldwide interoperability for microwave access;IEEE standards;frequency division multiple access;open systems;pricing;quality of service;radio access networks;telecommunication standards;},
doi={10.1109/WONS.2009.4801833},
ISSN={},}
- Hakyung Jung, Ji Hoon Lee, Chulhyun Park, Youngbin Im, Taekyoung Kwon and Yanghee Choi, "A Femtocell-based Testbed for Evaluating Future Cellular Networks," in Proc. International Conference on Future Internet Technologies (CFI) 2008, Seoul, Korea, June 2008.
This paper argues that the network community needs research testbeds for cellular wireless networks, and introduces a femtocell-based testbed, dubbed Cell-Lab, which is currently being developed for evaluating next-generation wireless network protocols. The Cell-Lab is being designed to support virtualization to enable multiple experiments simultaneously on top of femtocell base stations. In addition, open and remote access to the testbed, and integration with wired testbeds will be considered as basic features. To this end, our novel implementation strategy for achieving these goals and Cell-Lab's usage scenarios are described.
- Jaeyoung Choi, Chulhyun Park, Hakyung Jung, Taekyoung Kwon and Yanghee Choi, "Addressing in Future Internet: Problems, Issues, and Approaches," in Proc. International Conference on Future Internet Technologies (CFI) 2008, Seoul, Korea, June 2008.
The current Internet addressing has faced several challenges such as routing scalability, mobility and multi-homing support. To solve the current problems, it is required to redesign the basic principles of Internet addressing architecture. This paper investigates the major requirements of addressing, and pinpoints two viable principles for Future Internet: identifier / locator split and route-by-name. We also explore other research issues in designing an addressing architecture.
- Rui Zhang, Taerim Park, Myung J. Lee, Hakyung Jung, Jaehong Ryu, "Testbed Experimentation of a Meshed Tree Routing with Local Link State for Wireless PAN Mesh," in Proc. IEEE International Conference on Communications (ICC) 2008, Beijing, China, May 2008.
This paper focus on the testbed experimentation of a meshed tree routing algorithm with local link state for Wireless Personal Area networks (WPANs) based on current IEEE 802.15.4 MAC and PHY. The meshed tree uses a block addressing scheme based on tree structure and local link state information for mesh routing. Our approach exploits the information from the global tree structure for the direction of packet forwarding and local link state for choosing the next hop toward the destination. It has two prominent features: scalability and fault tolerance. Each node maintains a local link state of k-hop(usually 2-hop) information regardless of network size, which makes the approach scalable. Being a mesh, our approach shows good fault tolerance and load balancing. Testbed experiments show that the meshed tree displays superior performance when compared with AODV and a tree based algorithm. Comparisons were made with respect to packet deliver ratio, energy consumption and memory usage. The proposed algorithm is being considered as the routing algorithm for IEEE 802.15.5 WPAN Mesh standard.
@INPROCEEDINGS{4533612,
author={Rui Zhang and Tae Rim Park and Lee, M.J. and Hakyung Jung and Jaehong Ryu},
booktitle={Communications, 2008. ICC '08. IEEE International Conference on}, title={Testbed Experimentation of a Meshed Tree Routing with Local Link State for Wireless PAN Mesh},
year={2008},
month=may,
volume={},
number={},
pages={3060 -3065},
keywords={IEEE 802.15.4;MAC;PHY;WPAN;block addressing;fault tolerance;load balancing;local link state;mesh routing;meshed tree routing;packet forwarding;wireless personal area networks;access protocols;network theory (graphs);personal area networks;telecommunication network routing;trees (mathematics);wireless channels;},
doi={10.1109/ICC.2008.576},
ISSN={},}
- Hakyung Jung, Kideok Cho, Yongho Seok, Taekyoung Kwon and Yanghee Choi, "RARA: Rate Adaptation Using Rate-adaptive Acknowledgment for IEEE 802.11 WLANs," in Proc. IEEE Consumer Communications & Networking Conference (CCNC) 2008, Las Vegas, USA, January 2008.
The IEEE 802.11 standards support multiple bit rates at the physical layer so that stations can maximize the system performance by controlling the transmission rate responding to the conditions of underlying time-varying channels. This paper proposes a novel scheme, termed as Rate Adaptation using Rate-adaptive Acknowledgment (RARA). The key idea of RARA is to regulate the ACK transmission rate as a means to dictate the sender to adjust the data transmission rate. Compared with previous works, the proposed scheme can react quickly to the prevailing conditions by the receiver-based decision while inducing marginal overhead. Simulation results show that the RARA consistently outperforms other rate adaption schemes.
- Hakyung Jung, Yongho Seok, Taekyoung Kwon and Yanghee Choi, "A Scalable Rate Adaptation Mechanism for IEEE 802.11e Wireless LANs," in Proc. International Conference on Future Generation Communication and Networking (FGCN) 2007, Jeju Island, Korea, December 2007.
Although many rate adaptation schemes have been introduced to efficiently utilize the multiple transmission rates of the IEEE 802.11 standard, Automatic Rate Fallback (ARF) is the most widely implemented scheme on the market because of its simplicity. Our study reveals that the ARF malfunctions severely when it is used over IEEE 802.11e WLANs. The reason is that the intolerably shortened range of contention window for voice access category induces frequent collisions even when a small number of users contend. This paper demonstrates the inefficiency of the ARF using an analytic model and proposes a new rate adaptation scheme that maintains scalability. Simulation reveals that our scheme performs consistently well compared to the ARF scheme.
- Yongsub Nam, Taekyoung Kwon, Hojin Lee, Hakyung Jung, and Yanghee Choi, "Guaranteeing the network lifetime in wireless sensor networks: A MAC layer approach," in Elsevier Computer Communications (COMCOM), Vol. 30, No. 13, pp. 2532-2545, September 2007.
Energy is the most crucial but scarce resource in wireless sensor networks (WSNs). A wealth of MAC protocols are proposed only to prolong the network lifetime for energy-efficiency; whereas, others are tailored to reduce end-to-end latency in addition to extending the network lifetime. Since the requirements depend on the applications of the network, it would be difficult to design a single MAC that satisfies the wide range of applications. Specifically, some WSNs are required to survive for a certain lifetime because of too expensive deployment cost (e.g., harsh or hostile environments) to replace the energy-depleted sensor nodes. Furthermore, the portion of surviving sensor nodes can be a critical factor to satisfy the quality of surveillance (QoSv) requirements. In this paper, we propose a new adaptive MAC (A-MAC) protocol that not only guarantees the pre-configured network lifetime but also reduces the end-to-end latency. Basically, each sensor node adapts its duty cycle depending on the traffic load it suffers. By doing so, the energy consumption rate of each node approaches to the ideal energy consumption rate, which enables the node to survive for the pre-configured lifetime. Also, if a node suffers relatively less load, it can reduce the sleep delay by increasing its duty cycle. Analysis and simulation results exhibit that the proposed protocol shows less delay than S-MAC [W. Ye, J. Heidemann, D. Estrin, Medium access control with coordinated adaptive sleeping for wireless sensor networks, in: IEEE/ACM Transactions on Networking, vol. 12, No. 3, June 2004.] while meeting the network lifetime requirements.
@article{Nam:2007:GNL:1287850.1288068,
author = {Nam, Yongsub and Kwon, Taekyoung and Lee, Hojin and Jung, Hakyung and Choi, Yanghee},
title = {Guaranteeing the network lifetime in wireless sensor networks: A MAC layer approach},
journal = {Comput. Commun.},
volume = {30},
issue = {13},
month = {September},
year = {2007},
issn = {0140-3664},
pages = {2532--2545},
numpages = {14},
url = {http://portal.acm.org/citation.cfm?id=1287850.1288068},
doi = {10.1016/j.comcom.2007.05.031},
acmid = {1288068},
publisher = {Butterworth-Heinemann},
address = {Newton, MA, USA},
keywords = {Adaptation, Duty cycle, Medium access control (MAC), Network lifetime, Wireless sensor network},
}
- Yongsub Nam, Hojin Lee, Hakyung Jung, Taekyoung Kwon, and Yanghee Choi, "An Adaptive MAC (A-MAC) Protocol Guaranteeing Network Lifetime for Wireless Sensor Networks," in Proc. European Wireless (EW) 2006, Athens, Greece, April 2006.
Wireless sensor networks (WSNs) have a wide range of potential applications, a majority of which may be required to survive for a pre-configured lifetime since it is hard or costly to re-deploy sensor nodes to where a sensing hole has taken place. A sensing hole may occur when specific nodes suffer more traffic load than others and thus exhaust initially supplied energy. We propose an adaptive MAC (A-MAC) protocol for WSNs to tackle the sensing hole problem, which keeps the entire network operating for a required lifetime. The main concern in designing A-MAC is two-folded: guaranteeing the pre-configured network lifetime, and minimizing end-to-end latency. In order to achieve both goals, A-MAC introduces an adaptive duty cycle depending on ratio of the remaining energy to the initially supplied energy considering the pre-configured lifetime. The more energy a node has, the more frequently the node will wake up and hence fasten relaying data. As a consequence, each node is expected to run out of energy around the end of the pre-configured network lifetime. Also, nodes with more energy are utilized to minimize end-to-end delay. Simulation results exhibit significantly lower latency of A-MAC while guaranteeing the pre-configured network lifetime.
- Hakyung Jung, Nakjung Choi, Yongho Seok, Taekyoung Kwon, and Yanghee Choi, "Augmented Split-TCP over Wireless LANs," in Proc. IEEE International Conference on Communications (ICC) 2006, Istanbul, Turkey, June 2006.
This paper introduces a new split-TCP approach for improving TCP performance over IEEE 802.11-based wireless LANs. TCP over wireless LANs is not aggressive, which is a fundamental reason for poor performance. We propose augmented split-TCP (AS-TCP) to mitigate this problem. Our scheme extends the split-connection approach that divides a connection into two different connections at a split point such as an access point. Using AS-TCP, a mobile host emulates TCP ACK packets using MAC ACK frames, instead of receiving real TCP ACK packets. We compared AS-TCP with both normal TCP and I-TCP (indirect TCP) by simulation. Results show that AS-TCP achieves higher throughput, fairer resource allocation and, in power-saving mode, shorter delays.
- Sangheon Pack, Hakyung Jung, Taekyoung Kwon, and Yanghee Choi, "SNC: A Selective Neighbor Caching Scheme for Fast Handoff in IEEE 802.11 Wireless Networks,” ACM SIGMOBILE Mobile Computing and Communications Review (MC2R), Vol. 9, No. 4, pp. 39-49, October 2005.
Mobility support is one of the most challenging issues in IEEE 802.11 networks. In the proactive neighbor caching (PNC) scheme, when a mobile host is connected to an access point (AP), its context (e.g. security association or QoS information) is propagated in advance to all of the AP’s neighbors to reduce handoff processing time. In this paper, we propose a selective neighbor caching (SNC) scheme, which propagates a mobile host’s context only to the selected neighbor APs considering handoff patterns. Therefore, the SNC scheme can reduce the message overhead on the links among APs. We evaluate the performance of the SNC and PNC schemes in terms of the cache hit probability and the signaling cost. Especially, we investigate the effect of mobility and cache size through extensive simulations. The results reveal that the SNC scheme provides a comparable cache hit probability while significantly reducing the signaling overhead in IEEE 802.11 networks. Moreover, although the SNC propagates relatively a small number of contexts to neighbor APs, the SNC scheme outperforms the PNC scheme when the cache size is small and the mobility is low.
@article{Pack:2005:SSN:1096166.1096172,
author = {Pack, Sangheon and Jung, Hakyung and Kwon, Taekyoung and Choi, Yanghee},
title = {SNC: a selective neighbor caching scheme for fast handoff in IEEE 802.11 wireless networks},
journal = {SIGMOBILE Mob. Comput. Commun. Rev.},
volume = {9},
issue = {4},
month = {October},
year = {2005},
issn = {1559-1662},
pages = {39--49},
numpages = {11},
url = {http://doi.acm.org/10.1145/1096166.1096172},
doi = {http://doi.acm.org/10.1145/1096166.1096172},
acmid = {1096172},
publisher = {ACM},
address = {New York, NY, USA}, }
- Sangheon Pack, Hakyung Jung, Taekyoung Kwon, and Yanghee Choi, "A Selective Neighbor Caching Scheme for Fast Handoff in IEEE 802.11 Wireless Networks," in Proc. IEEE International Conference on Communications (ICC) 2005, Seoul, Korea, May 2005.
Mobility support in IEEE 802.11 networks is a challenging issue. Recently, a new scheme called proactive neighbor caching (PNC) was proposed and adopted as an IEEE standard. The PNC scheme introduces a neighbor graph, which dynamically captures the mobility topology of a wireless network for pre-positioning a mobile host (MH)’s context. However, the PNC scheme may result in significant signaling overhead because the MH’s context is propagated to all neighbor access points (APs). In this paper, we propose a selective neighbor caching (SNC) scheme, which propagates a MH’s context to only the selected neighbor APs considering handoff frequencies between APs. When the context transfer is needed, neighbor APs with equal handoff probabilities to or higher handoff probabilities than a predefined threshold value are selected. We also derive an optimal threshold value when the target cache hit probability is given. Simulation results reveal that the SNC scheme significantly reduces the signaling overhead while guaranteeing a comparable cache hit probability compared to the PNC scheme.
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Introduction