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Cho Y.,Broadcasting and Telecommunications Convergence Research Laboratory | Radha H.,Michigan State University | Seo J.,Broadcasting and Telecommunications Convergence Research Laboratory | Kang J.,Broadcasting and Telecommunications Convergence Research Laboratory | Hong J.,Creative and Challenging Research Division
ETRI Journal | Year: 2010

The overall channel capacity of a multihop wireless path drops progressively over each hop due to the cascading effect of noise and interference. Hence, without optimal rate adaptation, the video quality is expected to degrade significantly at any client located at a far-edge of an ad-hoc network. To overcome this limitation, decoding and forwarding (DF), which fully decodes codewords at each intermediate node, can be employed to provide the best video quality. However, complexity and memory usage for DF are significantly high. Consequently, we propose syndrome-based partial decoding (SPD). In the SPD framework an intermediate node partially decodes a codeword and relays the packet along with its syndromes if the packet is corrupted. We demonstrate the efficacy of the proposed scheme by simulations using actual 802.11b wireless traces. The trace-driven simulations show that the proposed SPD framework, which reduces the overall processing requirements of intermediate nodes, provides reasonably high goodput when compared to simple forwarding and less complexity and memory requirements when compared to DF. Copyright © 2010 ETRI. Source


Yoon J.,Sungkyunkwan University | Lee S.,Sungkyunkwan University | Shin J.,Sungkyunkwan University | Won S.H.,Creative and Challenging Research Division
Proceedings - 7th International Conference on Digital Content, Multimedia Technology and Its Applications, IDCTA 2011 | Year: 2011

Recently, relay-based cooperative system has drawn much attention. There are several technical components to be considered in this relay system such as multiple antenna schemes, network coding, etc. In this paper, we do a performance analysis using a combination of multiple-input multiple-output (MIMO) techniques and network coding in a wireless relay-based cooperative system having multiple nodes to send data toward one destination via one relay node which performs network coding. For the performance analysis, we derive overall error probability and channel capacity for multi-user uplink relay-based cooperative communication. The results show that the changes among MIMO modes (i.e., spatial multiplexing or diversity mode) at the transmission between source-to-relay or relay-to-destination is useful to maximize system capacity. Also this analysis can decide an optimal switching point of SNR for different MIMO modes in terms of average signal-to-noise ratio (SNR) in order to achieve best performance. Thus, a practical guidance of combined scheme using network coding and MIMO can be derived. © 2011 AICIT. Source


Park J.,Sungkyunkwan University | Lee S.,Sungkyunkwan University | Kim T.,Sungkyunkwan University | Shin J.,Sungkyunkwan University | Won S.H.,Creative and Challenging Research Division
Proceedings - 7th International Conference on Digital Content, Multimedia Technology and Its Applications, IDCTA 2011 | Year: 2011

This paper proposes a low-complexity bit-allocation scheme for video transmission of the scalable extension of H.264/AVC (SVC). The proposed method consists of SVC source-layer encoding and layered forward error correction (FEC) using LDPC channel codes. The experimental results show that the proposed scheme provides similar video quality when comparing with full-search method, but it has much lower computational complexity. Thus, the proposed method is more suitable for the real-time video streaming service. © 2011 AICIT. Source


Han Y.-T.,Convergence Components and Material Research Laboratory | Han Y.-T.,Korea Advanced Institute of Science and Technology | Shin J.-U.,Convergence Components and Material Research Laboratory | Park S.-H.,Convergence Components and Material Research Laboratory | And 5 more authors.
ETRI Journal | Year: 2011

This letter presents a polymer 1×2 thermo-optic totalinternal- reflection digital optical switch (TIR-DOS) with an index contrast of 1.5%-Δ operating at low power consumption. The structure of our 1×2 TIR-DOS was created by adding a reflection port to that of a conventional multimode filtering variable optical attenuator. To improve the total-internalreflection efficiency, a heater offset was applied to the crossing region of multimode waveguides of the TIR-DOS. The fabricated 1×2 TIR-DOS shows a low electrical power consumption of 18 mW for an on-off ratio of 35 dB. © 2011 ETRI. Source


Nguyen T.D.,Chonnam National University | Kim J.H.,Chonnam National University | Kim S.H.,Chonnam National University | Yang H.J.,Chonnam National University | And 3 more authors.
ETRI Journal | Year: 2012

A novel interaction method for mobile phones using their built-in cameras is presented. By estimating the path connecting the center points of frames captured by the camera phone, objects of interest can be easily extracted and recognized. To estimate the movement of the mobile phone, corners and corresponding Speeded-Up Robust Features descriptors are used to calculate the spatial transformation parameters between the previous and current frames. These parameters are then used to recalculate the locations of the center points in the previous frame into the current frame. The experiment results obtained from real image sequences show that the proposed system is efficient, flexible, and able to provide accurate and stable results. © 2012 ETRI. Source

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