HEE WOOK KIM - Academia.edu (original) (raw)

Papers by HEE WOOK KIM

We are living in the world in which resources are limited compared to the traffic demands, which ... more We are living in the world in which resources are limited compared to the traffic demands, which are increasing rapidly. In this environment, it is essential for the resource management techniques to maximize the effectiveness of the resource utilization. In particular, since the satellite resource such as on-board power, bandwidth even beam itself are expensive and limited due to its inherent characteristics, an effort to enhance the efficiency on their utilization is crucial. In this paper, we consider beam resource management in the N multi-beam satellite system. The simulation result demonstrates that the proposed scheme selecting only K(≤N) active beams assigning the beam power can achieve the increase of a total throughput compared to the non-selective beam allocation. Keywords-beam selection; resource management; multibeam satellite; wireless communication

ETRI Journal, 2014

An integrated multi-beam satellite and multi-cell terrestrial system is an attractive means for h... more An integrated multi-beam satellite and multi-cell terrestrial system is an attractive means for highly efficient communication due to the fact that the two components (satellite and terrestrial) make the most of each other's resources. In this paper, a terrestrial component reuses a satellite's resources under the control of the satellite's network management system. This allows the resource allocation for the satellite and terrestrial components to be coordinated to optimize spectral efficiency and increase overall system capacity. In such a system, the satellite resources reused in the terrestrial component may bring about severe interference, which is one of the main factors affecting system capacity. Under this consideration, the objective of this paper is to achieve an optimized resource allocation in both components in such a way as to minimize any resulting inter-component interference. The objective of the proposed scheme is to mitigate this intercomponent interference by optimizing the total transmission power-the result of which can lead to an increase in capacity. The simulation results in this paper illustrate that the proposed scheme affords a more energyefficient system to be implemented, compared to a conventional power management scheme, by allocating the bandwidth uniformly regardless of the amount of interference or traffic demand.

The Journal of Korean Institute of Communications and Information Sciences, 2015

In this paper, we propose an efficient resource allocation scheme for the integrated satellite/te... more In this paper, we propose an efficient resource allocation scheme for the integrated satellite/terrestrial networks. The proposed scheme is a frequency sharing technique to mitigate the inter-component interferences which can be generated between a satellite beam and terrestrial cells that are operated in the same frequency. The proposed dynamic resource allocation scheme can mitigate the total inter-component interference by optimizing the total transmission power and it can expect a result of which can lead to an increase in capacity. In such a system, the interference situation can be affected by the distributed traffic demands or up/down link communications environments. In this point of view, we evaluate the performance of the total consumed power, the amount of inter-component interference with respect to different traffic distributions and interference environments between the satellite beam and terrestrial systems.

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2013

In this paper, a candidate satellite radio interface, satellite orthogonal frequency division mul... more In this paper, a candidate satellite radio interface, satellite orthogonal frequency division multiplexing (SAT-OFDM), for the satellite component of IMT-Advanced is presented. The SAT-OFDM is based on long term evolution (LTE) terrestrial radio interface for maximum commonality with IMT-Advanced terrestrial radio interface. This paper deals with the configuration and performance of the 3GPP LTE based satellite radio interface. And then, as an enhancement of the satellite-specific radio interface, it addresses the possible adaptation of 3GPP LTE to the satellite in order to maximize the performance over satellite link.

ETRI Journal, 2012

A multi-spot-beam satellite is an attractive technique for future satellite communications since ... more A multi-spot-beam satellite is an attractive technique for future satellite communications since it can support high data rates by projecting high power density to each spot beam and can reuse a frequency in different cells to increase the total system capacity. In this letter, we propose a resource management technique adjusting the bandwidth of each beam to minimize the difference between the traffic demand and allocated capacity. This represents a reasonable solution for dynamic bandwidth allocation, considering a trade-off between the maximum total capacity and fairness among the spot beams with different traffic demands.

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2011

Multibeam satellite networks can extend the service coverage as deploying its spot beam. It is im... more Multibeam satellite networks can extend the service coverage as deploying its spot beam. It is important to allocate the appropriate resources to downlink multibeams to prevent the unnecessary waste of resources in the satellite system. This paper presents an optimum beam allocation scheme for multi-spot beam satellite system, as beam bandwidth to be allocated is controlled dynamically. We apply the Lagrange theory to obtain the optimization formula for bandwidth allocation of each spot beam in order to meet the total bandwidth constraint. Eventually we can find out the optimum beam profile respect to bandwidth.

2012 IEEE Vehicular Technology Conference (VTC Fall), 2012

ABSTRACT Multi-beam satellite networks can extend the service coverage as deploying the spot beam... more ABSTRACT Multi-beam satellite networks can extend the service coverage as deploying the spot beams. It is important to allocate the appropriate resources to multi-beam downlinks to prevent the unnecessary waste of resources due to the inherent limitations of them, such as power, bandwidth, and even the use of a spot beam. In this paper, we propose a resource management technique adjusting the bandwidth of each beam, in which the difference between the traffic demand and allocated capacity is minimized. This represents a reasonable solution for flexible bandwidth allocation considering a trade-off between the maximum total capacity and fairness among the spot beams with different traffic demand. In addition, in order to improve the total system capacity, we present the flexible beam management algorithm. Meanwhile, the proposed flexible bandwidth allocation scheme does not yield a closed-form solution for the beam profile in terms of bandwidth. Therefore, we present the method to find optimal beam bandwidth via heuristic search.

2016 International Conference on Information and Communication Technology Convergence (ICTC), 2016

Necessity for interoperable control and non-payload communication technology and system deploymen... more Necessity for interoperable control and non-payload communication technology and system deployment is increased for safe unmanned aircraft system (UAS) operation as well as extension of UAS applications. For this, C-band frequency was globally allocated only for CNPC in world radio conference 2012 (WRC-12). The technology development and standardization activities for high reliable UAS CNPC operating in the C-band frequency has already been kicked off in US and efficient radio communication technologies are being considered with respect to the size, weight, power and cost (SWaP-C) of UAS. In this paper, we analyze the terrestrial radio waveform standardized in radio technical commission for aeronautics (RTCA) and make some proposals for its performance enhancement.

2014 International Conference on Information and Communication Technology Convergence (ICTC), 2014

Proximity-1 protocol developed by CCSDS is considered for a bi-directional proximate space links ... more Proximity-1 protocol developed by CCSDS is considered for a bi-directional proximate space links for the efficient support of deep space mission. The protocol can be considered for proximate space links for the space internet mission which expects to be included in Korean lunar project. However, considering the scenario of the space internet mission and the requirement of its communication payload, the proximity-1 protocol needs to be updated under the scenario of the space internet mission with high data rate and simplified under the requirement of its communication payload in terms of size, weight and power. In this paper, we will address design concept of the transmission layer of the proximate space links for Korean lunar project. Then we will propose candidate transmission layer features of the proximate space based on proximity-1 and other CCSDS standards.

2011 IEEE 73rd Vehicular Technology Conference (VTC Spring), 2011

ABSTRACT As a next generation mobile satellite network, an in- tegrated satellite and complementa... more ABSTRACT As a next generation mobile satellite network, an in- tegrated satellite and complementary ground component (CGC) network is recently considered in order to provide seamless, transparent and ubiquitous wireless coverage over the world. In this network, it is essential to reuse efficiently frequencies between satellite and CGC components under tolerable interference level. In this paper, we propose how the CGC can reuse satellite frequencies in an OFDMA based multi-beam mobile satellite system with frequency reuse factor 1. In our scheme, the CGC is operated via beam division multiple access (BDMA) for interference mitigation between satellite and CGC signals. Index Terms—BDMA, MSS, CGC, frequency reuse.

International Journal of Satellite Communications and Networking, 2010

ABSTRACT In this paper, we propose an efficient cooperative diversity scheme for mobile satellite... more ABSTRACT In this paper, we propose an efficient cooperative diversity scheme for mobile satellite multimedia broadcasting systems. The proposed scheme is a transmit diversity technique to adapt different channel environments, and thus we do not need any channel quality information from the return link. In the proposed scheme, we utilize space-time block coding (STBC) and rate compatible turbo codes in order to realize the transmit diversity for the mobile satellite system with several repeaters. The satellite and several repeaters operate in unison to send the encoded signals, so that the receiver may realize diversity gain. The simulation results demonstrate that the proposed scheme can provide highly improved performance.

2006 IEEE International Symposium on Consumer Electronics

ABSTRACT We present joint frame synchronization and frequency offset estimation using a new pream... more ABSTRACT We present joint frame synchronization and frequency offset estimation using a new preamble with pseudo-noise sequences in time domain for orthogonal frequency division multiplexing (OFDM) based wireless communication over Rician fading channel. By the proposed scheme, the accuracy of the timing offset estimator is definitely improved and an estimation range of the frequency offset normalized by the carrier spacing is extremely extended to one half of the total signal bandwidth with only one pilot symbol which has lower PAPR than those in conventional schemes. The performance of the proposed method is shown by simulation

International Journal of Satellite Communications and Networking, 2015

ABSTRACT This paper presents the satellite orthogonal frequency division multiplexing (SAT-OFDM) ... more ABSTRACT This paper presents the satellite orthogonal frequency division multiplexing (SAT-OFDM) technology as a satellite radio interface for international mobile telecommunications (IMT)-Advanced. The SAT-OFDM radio interface is designed to provide various advanced IMT services in satellite environments. For cost-effective deployment of a satellite IMT-Advanced system, the radio interface must have a high degree of commonality with third-generation partnership project long-term evolution (3GPP LTE) technology for IMT-Advanced, but it also has a number of different features. Those features are needed to adapt the 3GPP LTE technology for satellite-specific environments such as long round-trip delay, large cell size, and slow-fading satellite channel. In this paper, we summarize the key features of the SAT-OFDM technology and propose satellite specific features included in the SAT-OFDM technology as an adaption way of LTE over satellite. Then we show the performance evaluation results of the SAT-OFDM technology to see the feasibility of LTE over satellite. Copyright © 2015 John Wiley & Sons, Ltd.