The Experts below are selected from a list of 26259 Experts worldwide ranked by ideXlab platform
Dong In Kim - One of the best experts on this subject based on the ideXlab platform.
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hybrid backscatter communication for wireless Powered heterogeneous networks
IEEE Transactions on Wireless Communications, 2017Co-Authors: Sung Hoon Kim, Dong In KimAbstract:In this paper, we propose hybrid backscatter communication for wireless-Powered communication networks (WPCNs) to increase transmission range and provide uniform rate distribution in the heterogeneous network (HetNet) environment. In such HetNet, where the TV tower or high-Power Base Station (macrocell) coexists with densely deployed small-Power access points (e.g., small-cells or WiFi), users can operate in either bistatic scatter or ambient backscatter, or a hybrid of them, given that the harvested energy from the dedicated or ambient RF signals may not be sufficient enough to support the existing harvest-then-transmit protocol for WPCN, which is extended to the wireless-Powered heterogeneous network (WPHetNet). Considering the hybrid and dual mode operation, we formulate a throughput maximization problem depending on the user location, namely Macro-zone or WiFi-zone. After performing the optimal time allocation for the above operation, we show that the proposed hybrid backscatter communication can increase the transmission range of WPHetNet, while achieving uniform rate distribution.
Timo Aittooja - One of the best experts on this subject based on the ideXlab platform.
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high efficiency envelope tracking supply voltage modulator for high Power Base Station amplifier applications
International Microwave Symposium, 2010Co-Authors: Timo AittoojaAbstract:Wideband supply voltage modulator with efficiency of 85.1% at 120 W average output Power with 7.5dB PAPR (Peak to average Power ratio) (WCDMA, LTE, MC-GSM signals), and 91.7% at 130W output Power with 0dB PAPR (GSM applications), was built. Supply voltage modulator consists of a linear amplifier and a switching stage in parallel. The linear amplifier is controlled by an envelope signal, and a novel method for controlling the switching stage is presented, resulting in high efficiency and low sensitivity to component variations. Over 20%-unit efficiency improvement in back-off was achieved with the new control method. The measured efficiency was above 80% over 14dB average Power range with 7.5dB PAPR test signal. Demonstrator circuit was built from discrete commercial components. An ET PA implemented with demonstrator modulator exhibited -60dBc ACP linearity with dual carrier 7.5dB PAPR WCDMA signal. For more wideband and compact ET PA implementation integrated circuit (IC) was fabricated and ET PA implemented with the IC modulator achieved -58dBc ACP linearity with quad carrier 7.5dB PAPR WCDMA signal. Wideband operation required special design for PA supply feed line design.
Y Matsuda - One of the best experts on this subject based on the ideXlab platform.
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stability analysis and layout design of an internally stabilized multi finger fet for high Power Base Station amplifiers
International Microwave Symposium, 2003Co-Authors: S Goto, T Kunii, K Fujii, Akira Inoue, Y Sasaki, Y Hosokawa, Ryo Hattori, T Ishikawa, Y MatsudaAbstract:A high-Power, discrete, and internally-matched FET, such as for use in Base Station amplifiers, consists of lots of gate fingers to realize a very large periphery. It is well-known that many active devices combined in parallel likely form many closed loops and cause odd mode oscillation. However, stability analysis among FET fingers is usually complex, because of the existence of lots of active nodes. In this paper, novel internally stabilized multi-finger FET layout methodology with a branched gate feed structure is proposed, to stabilize among gate fingers without increasing the occupied layout area of the FET. The feature of this layout is that the branched gate feed structure, which can be fabricated without any extra processing step, functions as a resistor to isolate each FET cell. Stability analysis and layout design were achieved by using the NDF (Normalized Determinant Function) evaluation technique, which can deal with lots of active nodes. In an experiment for a GaAs FET of 134 mm gate width with 168 gate fingers, this stability analysis precisely predicted an oscillation frequency of the FET having multiple closed loops. The new approach presented here on the gate feed structure effectively suppressed odd mode oscillation.
Sung Hoon Kim - One of the best experts on this subject based on the ideXlab platform.
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hybrid backscatter communication for wireless Powered heterogeneous networks
IEEE Transactions on Wireless Communications, 2017Co-Authors: Sung Hoon Kim, Dong In KimAbstract:In this paper, we propose hybrid backscatter communication for wireless-Powered communication networks (WPCNs) to increase transmission range and provide uniform rate distribution in the heterogeneous network (HetNet) environment. In such HetNet, where the TV tower or high-Power Base Station (macrocell) coexists with densely deployed small-Power access points (e.g., small-cells or WiFi), users can operate in either bistatic scatter or ambient backscatter, or a hybrid of them, given that the harvested energy from the dedicated or ambient RF signals may not be sufficient enough to support the existing harvest-then-transmit protocol for WPCN, which is extended to the wireless-Powered heterogeneous network (WPHetNet). Considering the hybrid and dual mode operation, we formulate a throughput maximization problem depending on the user location, namely Macro-zone or WiFi-zone. After performing the optimal time allocation for the above operation, we show that the proposed hybrid backscatter communication can increase the transmission range of WPHetNet, while achieving uniform rate distribution.
S Goto - One of the best experts on this subject based on the ideXlab platform.
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stability analysis and layout design of an internally stabilized multi finger fet for high Power Base Station amplifiers
International Microwave Symposium, 2003Co-Authors: S Goto, T Kunii, K Fujii, Akira Inoue, Y Sasaki, Y Hosokawa, Ryo Hattori, T Ishikawa, Y MatsudaAbstract:A high-Power, discrete, and internally-matched FET, such as for use in Base Station amplifiers, consists of lots of gate fingers to realize a very large periphery. It is well-known that many active devices combined in parallel likely form many closed loops and cause odd mode oscillation. However, stability analysis among FET fingers is usually complex, because of the existence of lots of active nodes. In this paper, novel internally stabilized multi-finger FET layout methodology with a branched gate feed structure is proposed, to stabilize among gate fingers without increasing the occupied layout area of the FET. The feature of this layout is that the branched gate feed structure, which can be fabricated without any extra processing step, functions as a resistor to isolate each FET cell. Stability analysis and layout design were achieved by using the NDF (Normalized Determinant Function) evaluation technique, which can deal with lots of active nodes. In an experiment for a GaAs FET of 134 mm gate width with 168 gate fingers, this stability analysis precisely predicted an oscillation frequency of the FET having multiple closed loops. The new approach presented here on the gate feed structure effectively suppressed odd mode oscillation.