• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2621-2627
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• 2014

Directional transmission is one of key technology to solve the utmost problem that current mobile communication system faces, which is explosively increasing data traffic, since directional transmission can maximize the throughput of mobile communication systems. In this work, we consider power allocation scheme for mobile communication system which utilizing directional transmission. Especially, we consider the case in which multiple users in the same sector of base station, are served at the same time by utilizing directional transmission. For this scenarios, we consider equal power allocation scheme, Water-filling based scheme and inverse SNR scheme. Moreover, we propose beam power allocation scheme whose objective is to maximize overall system throughput by taking into account interference between different directional transmissions. Moreover, we have examined the spectral efficiency and Jain's fairness index of various power allocation schemes for directional transmission by using system level simulator that has been developed in our previous work. Through simulations, it has been verified that the proposed power allocation scheme can improve the spectral efficiency of the system by 28%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7A
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• pp.568-577
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• 2005

In this paper, we propose the transmission scheme for the space-time block coded spatial multiplexing systems that have adaptive rate and power allocation per each transmit antenna through the use of feedback information related to channel state. Simulation results show that the adaptive power and rate transmission scheme gain more than 4.5 dB over conventional equal-power and rate transmission scheme.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.65-70
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• 2013

In this paper, we propose a multi-hop cooperative transmission protocol to obtain energy savings in static wireless networks. Each terminal in the network is equipped with a single antenna and each receiver uses equal gain combining technique (EGC) to combine received signals. We also propose a power allocation strategy which optimizes the total transmit power at each stage. Monte-Carlo simulations are presented to evaluate and compare performance of the proposed protocol with the multi-hop direct transmission (MDT) and the cooperative routing protocol proposed by Khadani [8], in terms of the average total transmit power and the average number of required stages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12C
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• pp.1020-1028
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• 2010

Relay has attracted great attention due to its inherent capability to extend the service coverage and combat shadowing in next generation mobile communication systems. So far, most relay technologies have been developed under the half-duplex (HD) constraint that prevents relays from transmitting and receiving at the same time. Although half-duplex relay (HDR) is easy to implement, it requires partitioning of resource for transmission and reception, reducing the whole system capacity. In this paper, we propose a multinser precoding and power control scheme with sum rate matching for a full-duplex (FD) multiple-input multiple-output (MIMO) relay. Full-duplex relay (FDR) can overcome the drawback of HDR by transmitting and receiving on the same frequency at the same time, while it is crucial to reduce the effect of self-interference that is caused by its own transmitter to its own receiver. The proposed precoding scheme cancels the self-interference of the FDR as well as to support multiuser MIMO. Moreover, we suggest a power allocation scheme for FD MIMO relay with the constraint that the sum rate of the relay's received data streams is equal to that of the relay's transmit data streams.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.1006-1013
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• 2009

This paper proposes a data stream allocation technique for fair capacity performance in multiuser multiple-input multiple-output (MIMO) systems using block diagonalization (BD) algorithm. Conventional studies have been focused on maximum sum capacity. Thus, there is a very large difference of capacity among users, since user capacity unfairly distributed according to each user channel environment. In additional, poor channel user has very small capacity, since base station allocates the power by using water-filling technique. Also, almost studies limited itself to obtain the additional gain by using the same number of data streams for all users. In this paper, we propose the technique for maximizing sum capacity under the fair performance constraint by allocating data stream according to user channel environment. Also, proposed algorithm has more gain of sum capacity and transmit power than conventional equal allocation via computer simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.85-94
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• 2006

Simple-relay aided resource allocation (SRARA) schemes are incorporated with throughput guarantee scheduling (TGS) in IEEE 802.16 type TDD-OFDMA downlink to enhance service coverage, where the amount of resources at each relay is limited due to either its available power which is much smaller than base station (BS) power or the required overhead The performance of SRARA schemes is evaluated with both proportional fair (PF) and TGS schedulers at 64 kbps and 128 kbps user throughput requirements. For SRARA with RSs of relatively lower power, a scheme putting total power into only one subchannel shows larger coverage than when both subchnnels are used in a manner of equal power allocation, while the RS with evenly power-allocated two subchannels could provide larger coverage gain for a relatively higher power. In a lower target (64kbps), more improvement comes from relay scheme rather than scheduler design. For a relatively higher level (128 kbps), it comes from scheduler design rather than relay.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.2
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• pp.92-101
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• 2012

In this paper, we propose a distributed transmit power control algorithm for optimal end-to-end throughput in wireless multihop networks. Considering a solidarity property of link rates consisting of a multihop link and the fact that the multihop end-to-end throughput is determined by the minimum link rate, the proposed scheme controls the transmit power to make all link rates be equal and so maximizes the end-to-end throughput of multihop link. In addition, in the proposed scheme the transmit node calculates its transmit power autonomously in a distributed manner just through the information sharing with its neighbor nodes and so decreases the information sharing overhead. Simulation results show that the proposed scheme achieves significant improvements in terms of end-to-end throughput and power consumption compared with the conventional maximum equal power allocation scheme.

• Korean Journal of Agricultural Science
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• v.22 no.2
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• pp.209-222
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• 1995

To mitigate the development gap between urban and rural area, the government has implemented project planning as the Rural Integrated Development in each Gun level since 1986. On account of shortage of the development fund, the government had changed the Gun level development into Myeon level development so called the Rural Central Settlement Zone Development. The government had started nine pilot projects throughout Korea from 1990. This study is aimed at identifing problems that found in the course of implementation of the projects and recommending the new direction of the successful implementation of the projects in the future. The problems and directions found in the cource of project implementation were as follows: 1. Project implementation by investment priority considering economic and financial rate of return should be made. 2. Objective project planning should be made. 3. Equal allocation of the limited investment fund by group interest and egoism should be prohibited. 4. Enforcement of special man power should be taken into account. 5. Unification of the diversified existing terms and conditions of loans for house construction and improvement. 6. Road development oriented budget allocation should be improved. 7. Sufficient development fund should be procured considering the present rate of sufficiency of the project cost as 36%. 8. Sufficient supply of the credit loans for improvement of living environment of the farmers should be realized. 9. Rational implementation planning in connection with farm household income source development should be made.

• Current Optics and Photonics
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• v.8 no.4
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• pp.421-426
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• 2024

The use of stimulated emission depletion (STED) microscopy has significantly improved resolution beyond the limits imposed by diffraction; Furthermore, STED microscopy adopts a 4Pi-geometry to achieve an isotropic improvement in resolution. In isoSTED microscopy, a polarizing beam splitter and retarders are used in a 4Pi cavity to split beams of identical power, generating constructive and destructive interference for lateral and axial resolution improvements, respectively. The precise alignment of the retarders is crucial for optimizing the performance of isoSTED microscopy, because this orientation affects the quality of the depletion focus, necessitating zero intensity at the center. Incomplete destructive interference can lead to unwanted fluorescence inhibition, resulting in degraded resolution and contrast. However, measuring the intensity and polarization state in each optical path of the 4Pi cavity is complex and requires additional devices such as a power meter. Here, we propose a simple and accurate alignment method for the 4Pi cavity in isoSTED microscopy. Our approach demonstrates the equal allocation of power between upper and lower beam paths and achieves complete destructive interference using a polarizing beam displacer and a single CCD camera positioned outside the 4Pi cavity.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.69-81
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• 2021

While the fifth generation (5G) and beyond 5G (B5G) mobile communication networks are being rolled over the globe, several world-wide companies have already started to prepare the sixth generation (6G). Such 6G mobile networks targets ultra-reliable low-latency communication (URLLC). In this paper, we challenge to reduce the inherent latency of existing non-orthogonal multiple access (NOMA) in 5G networks of massive connectivity. First, we propose the novel unipodal binary pulse amplitude modulation (2PAM) NOMA, especially without SIC, which greatly reduce the latency in existing NOMA. Then, the achievable data rates for the unipodal 2PAM NOMA are derived. It is shown that for unequal gain channels, the sum rate of the unipodal 2PAM NOMA is comparable to that of the standard 2PAM NOMA, whereas for equal gain channels, the sum rate of the unipodal 2PAM NOMA is superior to that of the standard 2PAM NOMA. In result, the unipodal 2PAM could be a promising modulation scheme for NOMA systems toward 6G.