Prof. Bang Chul Jung
Chungnam National University, Republic of Korea
'%3e%3cpath%20d='M22.1642%2019.0924C21.7317%2018.068%2021.1041%2017.1375%2020.3163%2016.3527C19.5309%2015.5656%2018.6006%2014.9381%2017.5766%2014.5048C17.5674%2014.5002%2017.5582%2014.4979%2017.5491%2014.4933C18.9774%2013.4616%2019.9059%2011.7811%2019.9059%209.88504C19.9059%206.74408%2017.3611%204.19922%2014.2201%204.19922C11.0792%204.19922%208.53429%206.74408%208.53429%209.88504C8.53429%2011.7811%209.46282%2013.4616%2010.8912%2014.4956C10.882%2014.5002%2010.8728%2014.5025%2010.8636%2014.5071C9.83652%2014.9404%208.91487%2015.5617%208.1239%2016.355C7.33685%2017.1404%206.70933%2018.0707%206.276%2019.0947C5.85031%2020.0972%205.62072%2021.172%205.59967%2022.2609C5.59905%2022.2853%205.60335%2022.3097%205.61229%2022.3325C5.62123%2022.3553%205.63465%2022.376%205.65174%2022.3935C5.66883%2022.4111%205.68926%2022.425%205.71182%2022.4345C5.73437%2022.444%205.7586%2022.4489%205.78308%2022.4489H7.15868C7.25956%2022.4489%207.3398%2022.3686%207.3421%2022.2701C7.38795%2020.5001%208.09868%2018.8425%209.35506%2017.5861C10.655%2016.2862%2012.3814%2015.5709%2014.2201%2015.5709C16.0588%2015.5709%2017.7852%2016.2862%2019.0852%2017.5861C20.3415%2018.8425%2021.0523%2020.5001%2021.0981%2022.2701C21.1004%2022.3709%2021.1807%2022.4489%2021.2815%2022.4489H22.6571C22.6816%2022.4489%2022.7058%2022.444%2022.7284%2022.4345C22.751%2022.425%2022.7714%2022.4111%2022.7885%2022.3935C22.8056%2022.376%2022.819%2022.3553%2022.8279%2022.3325C22.8369%2022.3097%2022.8412%2022.2853%2022.8406%2022.2609C22.8176%2021.165%2022.5907%2020.0989%2022.1642%2019.0924ZM14.2201%2013.8284C13.1678%2013.8284%2012.1773%2013.418%2011.4322%2012.6729C10.6871%2011.9278%2010.2767%2010.9374%2010.2767%209.88504C10.2767%208.83271%2010.6871%207.84227%2011.4322%207.09715C12.1773%206.35204%2013.1678%205.94165%2014.2201%205.94165C15.2724%205.94165%2016.2629%206.35204%2017.008%207.09715C17.7531%207.84227%2018.1635%208.83271%2018.1635%209.88504C18.1635%2010.9374%2017.7531%2011.9278%2017.008%2012.6729C16.2629%2013.418%2015.2724%2013.8284%2014.2201%2013.8284Z'%20fill='%238590A2'/%3e%3c/g%3e%3c/svg%3e)
Co-authors
Following
Followers
Research Focus & Metrics
Explore full metrics on Scilit
Academic Career Length
24Years (2003-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications20 February 2009 in IEEE Transactions on Wireless Communications
Journal Article
We investigate the effects of multi-user diversity in a spectrum sharing system where secondary users restrictively utilize a spectrum licensed to primary users only if interference perceived at primary users is regulated below a predetermined level. This interference regulation affects the characteristics of multiuser diversity gains previously known in non-spectrum sharing systems. Our numerical and analytical results show that the multiuser diversity gain in a spectrum sharing system increases differently according to conditions given by the transmit power of secondary users, P, and a predetermined interference temperature, Q - if P is sufficiently larger than Q, the multiuser diversity gain in terms of capacity scales like log2 (W (Ns)) similarly to a previously known scaling law in the non-spectrum sharing systems, where W(middot) and Ns denote a Lambert W function and the number of secondary transmitters, respectively. However, the scaling law of multiuser diversity gain becomes log2(Ns) as P becomes sufficiently larger such that P Gt QNs.
10 March 2017 in IEEE Transactions on Vehicular Technology
Journal Article
HJHu Jin
Hu Jin
WTWaqas Tariq Toor
Waqas Tariq Toor
Bang Chul JungJSJun-Bae Seo
Jun-Bae Seo
Commercial long-term evolution (LTE) systems adopt an access class barring (ACB) mechanism in the initial random access procedure with multiple preambles in order to accommodate bursty traffic arrivals of machine-type communications. In this paper, we propose two Bayesian ACB algorithms that estimate the number of active machine devices based only on the number of idle preambles in each slot. In the commercial LTE systems, eNodeB cannot instantaneously distinguish if a particular preamble is sent from a single device (i.e., success) or multiple devices (i.e., collision). However, the idle preambles can be instantaneously detected at the base station (BS) in each slot. Numerical results show that the proposed algorithms yield quite similar performance with the ideal ACB algorithm, assuming that the exact number of active devices is known to the eNodeB.
17 December 2010 in IEEE Communications Letters
Journal Article
Bang Chul JungWSWon-Yong Shin
Won-Yong Shin
We introduce an opportunistic interference alignment (OIA) for cellular networks, where a user scheduling strategy is utilized in time-division duplexing uplink communication environments with time-invariant channel coefficients and multi-antenna base stations (BSs). In the OIA scheme, each BS opportunistically selects users who generate the minimum interference to the other BSs. More specifically, each BS broadcasts its pre-designed interference directions, e.g., orthonormal random vectors, to all the users in other cells. Then, each user computes the amount of its generating interference, affecting the other BSs, and feedbacks it to its home cell BS. Note that the proposed OIA does not require global channel state information, time/frequency expansion, and a number of iterations, thereby resulting in easier implementation. Simulation results show that the proposed scheme provides significant improvement in terms of sum rates.
5 August 2019 in IEEE Transactions on Vehicular Technology
Journal Article
JYJeong Seon Yeom
Jeong Seon YeomHJHan Seung Jang
Han Seung JangKKKabseok Ko
Kabseok KoBang Chul JungWe mathematically derive an upper bound of bit- error rate (BER) of $uplink$ non-orthogonal multiple access sys- tems with quadrature phase shift keying (QPSK) modulation in fading channels. In particular, we exploit the $joint\, maximum-likelihood$ (ML) detector at a base station (BS) with multiple antennas since it results in the $optimal$ BER performance of a super-imposed QPSK modulated symbols from multiple mobile stations (MSs). In particular, we obtain a closed-form integral of Q-function with Erlang distributed random variable to derive the BER. We also obtain diversity order of the uplink NOMA systems. Through extensive computer simulations, we validate that our analytical results match well with the simulation results especially in high signal-to-noise ratio (SNR) regime.
3 April 2013 in IEEE Transactions on Wireless Communications
Journal Article
HYHyun Jong Yang
Hyun Jong Yang
WSWon-Yong Shin
Won-Yong Shin
Bang Chul JungAPArogyaswami Paulraj
Arogyaswami Paulraj
We consider the K-cell multiple-input multiple-output (MIMO) interfering multiple-access channel (IMAC) with time-invariant channel coefficients, where each cell consists of a base station (BS) with M antennas and N users having L antennas each. In this paper, we propose two opportunistic interference alignment (OIA) techniques utilizing multiple transmit antennas at each user: antenna selection-based OIA and singular value decomposition (SVD)-based OIA. Their performance is analyzed in terms of user scaling law required to achieve KS degrees-of-freedom (DoF), where S(≤ M) denotes the number of simultaneously transmitting users per cell. We assume that each selected user transmits a single data stream at each time-slot. It is shown that the antenna selection-based OIA does not fundamentally change the user scaling condition if L is fixed, compared with the single-input multiple-output (SIMO) IMAC case, which is given by SNR (K-1)S , where SNR denotes the signal-to-noise ratio. In addition, we show that the SVD-based OIA can greatly reduce the user scaling condition to SNR (K-1)S-L+1 through optimizing a weight vector at each user. Simulation results validate the derived scaling laws of the proposed OIA techniques. The sum-rate performance of the proposed OIA techniques is compared with the conventional techniques in MIMO IMAC channels and it is shown that the proposed OIA techniques outperform the conventional techniques.
18 May 2012 in IEEE Transactions on Communications
Journal Article
We introduce an opportunistic interference mitigation (OIM) protocol, where a user scheduling strategy is utilized in K-cell uplink networks with time-invariant channel coefficients and base stations (BSs) having M antennas. Each BS opportunistically selects a set of users who generate the minimum interference to the other BSs. Two OIM protocols are shown according to the number of simultaneously transmitting users per cell, S: opportunistic interference nulling (OIN) and opportunistic interference alignment (OIA). Then, their performance is analyzed in terms of degrees-of-freedom (DoFs). As our main result, it is shown that KM DoFs are achievable under the OIN protocol with M selected users per cell, if the total number of users in a cell, N, scales at least as SNR(K-1)M. Similarly, it turns out that the OIA scheme with S(<;M) selected users achieves KS DoFs, if N scales faster than SNR(K-1)S. These results indicate that there exists a trade-off between the achievable DoFs and the minimum required N. By deriving the corresponding upper bound on the DoFs, it is shown that the OIN scheme is DoF-optimal. Finally, numerical evaluation, a two-step scheduling method, and the extension to multi-carrier scenarios are shown.
About Me
Prof. Bang Chul Jung received a B.S. degree in Electronics Engineering from Ajou University, Suwon, Korea, in 2002 and an M.S. and Ph.D. degree in Electrical Computer Engineering from Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea, in 2004 and 2008, respectively. He was a senior researcher/research professor with KAIST Institute for Information Technology Convergence, Daejeon, Korea, from January 2009 to February 2010. From March 2010 to August 2015, he was a faculty of Gyeongsang National University, Tongyeong, Korea. He is currently a Professor at the Dept. of EE, Chungnam National University, Daejeon, Korea. Prof. Jung has served as an Associate Editor of IEEE Vehicular Technology Magazine since May 2020. He has also served as an Associate Editor of MDPI Energies/Electronics since 2020 and IEICE Transactions on Fundamentals of Electronics, Communications, and Computer Sciences since 2018.
Dr. Jung was the recipient of the 5th IEEE Communication Society Asia-Pacific Outstanding Young Researcher Award in 2011, the KICS Haedong Young Scholar Award in 2015, and the 29th KOFST Science and Technology Best Paper Award in 2019. His research interests include wireless communications, statistical signal processing, information theory, interference management, radar signal processing, spectrum sharing, multiple antennas, multiple access techniques, radio resource management, machine learning, and deep learning.