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Topology Aggregation for Hierarchical Wireless Tactical Networks
( Wooguil Pak ),( Young-june Choi ) 한국인터넷정보학회 2011 KSII Transactions on Internet and Information Syst Vol.5 No.2
Wireless tactical network (WTN) is the most important present-day technology enabling modern network centric warfare. It inherits many features from WMNs, since the WTN is based on existing wireless mesh networks (WMNs). However, it also has distinctive characteristics, such as hierarchical structures and tight QoS (Quality-of-Service) requirements. Little research has been conducted on hierarchical protocols to support various QoS in WMN. We require new protocols specifically optimized for WTNs. Control packets are generally required to find paths and reserve resources for QoS requirements, so data throughput is not degraded due to overhead. The fundamental solution is to adopt topology aggregation, in which a low tier node aggregates and simplifies the topology information and delivers it to a high tier node. The overhead from control packet exchange can be reduced greatly due to decreased information size. Although topology aggregation is effective for low overhead, it also causes the inaccuracy of topology information; thus, incurring low QoS support capability. Therefore, we need a new topology aggregation algorithm to achieve high accuracy. In this paper, we propose a new aggregation algorithm based on star topology. Noting the hierarchical characteristics in military and hierarchical networks, star topology aggregation can be used effectively. Our algorithm uses a limited number of bypasses to increase the exactness of the star topology aggregation. It adjusts topology parameters whenever it adds a bypass. Consequently, the result is highly accurate and has low computational complexity.
FRFC: Fast Table Building Algorithm for Recursive Flow Classification
Wooguil Pak,Saewoong Bahk IEEE 2010 IEEE communications letters Vol.14 No.12
<P>Policy lookup is a very essential function in packet forwarding and network security. As it is becoming a main cause of bottleneck in many network systems, this letter introduces a new policy lookup algorithm called FRFC (Fast table building for Recursive Flow Classification). Although it is based on RFC which shows the best policy lookup speed but the worst policy table update speed, it achieves high performance in table update as well as policy lookup. FRFC divides the whole rule set into smaller sub-rule sets and by doing so, it speeds up the table building time by 50 times compared to RFC when the considered rule set size is 10,000. With the rule set size increasing, the performance gap becomes larger.</P>
Extending QR-Code to Estimated Directional Information to Provide Personalized services
Wooguil Pak,Youngrok Cha,Sunki Yeo 한국정보통신학회 2015 2016 INTERNATIONAL CONFERENCE Vol.7 No.1
Quick Response (QR) code is only used to obtain information encoded into the code. Therefore, we cannot provide personalized service with it. In this paper, we propose a new approach to enable personalized services for the customers with extended QR-codes. Proposed QR-code can provide not only embedded text but also directional information between QR-code reader. Based on additional information, the code can provide rich information and services for users.
Traffic Flow Estimation based Channel Assignment for Wireless Mesh Networks
( Wooguil Pak ),( Saewoong Bahk ) 한국인터넷정보학회 2011 KSII Transactions on Internet and Information Syst Vol.5 No.1
Wireless mesh networks (WMNs) provide high-speed backbone networks without any wired cable. Many researchers have tried to increase network throughput by using multi-channel and multi-radio interfaces. A multi-radio multi-channel WMN requires channel assignment algorithm to decide the number of channels needed for each link. Since the channel assignment affects routing and interference directly, it is a critical component for enhancing network performance. However, the optimal channel assignment is known as a NP complete problem. For high performance, most of previous works assign channels in a centralized manner but they are limited in being applied for dynamic network environments. In this paper, we propose a simple flow estimation algorithm and a hybrid channel assignment algorithm. Our flow estimation algorithm obtains aggregated flow rate information between routers by packet sampling, thereby achieving high scalability. Our hybrid channel assignment algorithm initially assigns channels in a centralized manner first, and runs in a distributed manner to adjust channel assignment when notable traffic changes are detected. This approach provides high scalability and high performance compared with existing algorithms, and they are confirmed through extensive performance evaluations.