Jun Heo

Korea University, Sŏul, Seoul, South Korea

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Publications (80)48.45 Total impact

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    ABSTRACT: A generalization of unequal error protection (UEP) rateless codes and distributed rateless codes for distributed relay networks is proposed. We consider a two-hop relaying network where a single source transmits UEP rateless coded data to a destination via multiple relays. At the relays, the UEP rateless coded symbols are re-encoded by distributed rateless codes (DRC) to minimize the redundancy at the second hop. Previously introduced UEP rateless codes (URC) have supported a limited number of importance classes, mostly two classes, and targeted importance levels suited to a specific application. In this paper, however, we formulate an optimization problem to provide optimal URC in terms of the symbol error rate (SER) given any specific number and strengths of importance levels. Next, another optimization is proposed to obtain DRC with the minimum SER at a given overhead, which utilizes information of common symbols among the relays. The optimization methods are based on the AND-OR tree analysis and sequential quadratic programming. In addition, we evaluate the minimum achievable end-to-end symbol error rates over the wireless relay networks.
    No preview · Article · Dec 2015 · IEEE Transactions on Communications
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    ABSTRACT: Several studies on fountain codes have proposed degree distribution optimization schemes to maximize symbol recovery rate. However, if the number of transmitted coded symbols is limited or the channel erasure probability is high, it may be impossible that a user recovers all of the data symbols regardless of degree distribution employed by the source. In this study, we focus on a new system model where one source transmits fountain-coded symbols to multiple users who already possess some data symbols and coded symbols. Assuming that each user can transmit a feedback packet containing its own state information before the source transmits coded symbols, we propose two types of degree distribution design schemes that are suitable for the system model. Simulation results demonstrate the efficiency of our proposed schemes by comparing with conventional methods in terms of symbol recovery rate and full recovery rate.
    No preview · Article · Sep 2015 · IEEE Transactions on Communications
  • Sung-Il Kim · Il-Min Kim · Jun Heo
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    ABSTRACT: We investigate secure transmission for multiuser relay networks, where the undesired users who are not selected for data reception may overhear the source message as eavesdroppers. In this system, the secrecy performance may deteriorate as the number of users increases, since the number of eavesdroppers also increases. To address this issue, we consider a multiuser relay scheme with cooperative jamming (MUCJ). In this scheme, the desired user sends a jamming signal to the relay while the source sends its message to the relay, and then the relay amplifies and forwards the received signal to the desired user. Since the jamming can be subtracted only at the desired user, it acts as interference to prevent the eavesdroppers from intercepting the source message. We propose an optimal user selection scheme for the MUCJ, which is optimal in the sense of maximizing the secrecy rate. For the existing multiuser relay scheme (MURS) without cooperative jamming and the MUCJ, we derive the ergodic secrecy rates and analyze the asymptotic secrecy rate gains. We reveal that the ergodic secrecy rate can be increased as the number of users grows and much higher secrecy rate can be achieved by the MUCJ.
    No preview · Article · Jul 2015 · IEEE Transactions on Wireless Communications
  • Kyunghoon Kwon · Jun Heo
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    ABSTRACT: This paper presents a Rate-Compatible Block Turbo Code (RC-BTC) with increased transmission capacity. The proposed RC-BTC uses a new algorithm called information augmenting scheme, and can achieve a higher code rate than conventional one. A new Error Location Finding (ELF) Decoding Algorithm is introduced to solve the decoding problem of the information augmenting scheme. As a result, a novel error-correcting capability of the BTC-applied Chase-ELF Hybrid Decoder, combining the previous Chase–Pyndiah algorithm and the proposed ELF algorithm, is demonstrated via Monte-Carlo simulation. In addition, the proposed code maximally increases the transmission capacity with the Chase-ELF Hybrid decoder using an information augmenting scheme.
    No preview · Article · Aug 2014 · Wireless Personal Communications
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    ABSTRACT: Efficient design of device-to-device (D2D) communication calls for D2D users to propose adaptive power allocation strategy and to establish reliable communication links while protecting the QoS of cellular communications. In this paper, we consider the D2D communication as an underlay to relay-assisted cellular networks. To maximize the ergodic capacity, we derive an optimal transmission power under an average power constraint. With the derived optimal transmission power, a transmission period selection strategy for D2D communication is firstly introduced to improve reliability. We derive the outage probability in closed forms and evaluate the ergodic capacity to show performances of the proposed system. Numerical results show that the D2D system can achieve high capacity gains by flexibly allocating transmission power based on channel state information and significantly enhance reliability by selecting a transmission period, while satisfying various QoS conditions for cellular communication.
    No preview · Article · Jun 2014 · Wireless Personal Communications
  • Jaeyoung Lee · Hyundong Shin · Jun Heo
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    ABSTRACT: In this paper, we consider decouple-and-forward (DCF) relaying, where the relay encodes and amplifies decoupled data using orthogonal space-time block codes (OSTBCs), to achieve the maximum diversity gain of multiple-input multiple-output (MIMO) amplify-andforward (AF) relaying. Since the channel status of all antennas is generally unknown and time-varying for cooperation in multi-antenna multiple-relay systems, we investigate an opportunistic relaying scheme for DCF relaying to harness distributed antennas and minimize the cooperation overheads by not using the global channel state information (CSI). In addition, for realistic wireless channels which have spatial fading correlation due to closelyspaced antenna configurations and poor scattering environments, we analyze the exact and lower bound on the symbol error probability (SEP) of the opportunistic DCF relaying over spatially correlated MIMO Rayleigh fading channels. Numerical results show that, even in the presence of spatial fading correlation, the proposed opportunistic relaying scheme is efficient and achieves additional performance gain with low overhead. Copyright © 2014 The Institute of Electronics, Information and Communication Engineers.
    No preview · Article · Jun 2014 · IEICE Transactions on Communications
  • Kwangseok Noh · Saejoon Kim · Jun Heo
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    ABSTRACT: The third generation partnership project (3GPP) and digital video broadcasting-handheld standards recommend systematic Raptor codes as application-layer forward error correction for reliable transmission of multimedia data. In all previous studies on systematic Raptor codes, equal error protection for all data was considered. However, in many applications, multimedia data requires unequal error protection (UEP) that provides different levels of protection to different parts of multimedia data. In this paper, we propose a new design method for Raptor codes that provide both UEP and systematic properties over binary erasure channels. Numerical results show that the proposed UEP design is effective for reliable multi-level protection.
    No preview · Article · Apr 2014 · Wireless Personal Communications
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    ABSTRACT: In this paper, we introduce a unified framework to construct entanglement-assisted quantum error-correcting codes, including additive and nonadditive codes, based on the codeword stabilized framework on subsystems. The codeword stabilized (CWS) framework is a scheme to construct quantum error-correcting codes (QECCs) including both additive and nonadditive codes, and gives a method to construct a QECC from a classical error-correcting code in standard form. Entangled pairs of qubits (ebits) can be used to improve capacity of quantum error correction. In addition, it gives a method to overcome the dual-containing constraint. Operator quantum error correction (OQEC) gives a general framework to construct quantum error-correcting codes. We construct OQEC codes with ebits based on the CWS framework. This new scheme, entanglement-assisted operator codeword stabilized (EAOCWS) quantum codes, is the most general framework we know of to construct both additive and nonadditive codes from classical error-correcting codes. We describe the formalism of our scheme, demonstrate the construction with examples, and give several EAOCWS codes.
    Full-text · Article · Nov 2013
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    ABSTRACT: This paper provides a strategy for multihop transmission with decode-and-forward (DF) in a Poisson field of interferers. We analyze the optimal linear multihop system such as optimal resource allocation, optimal placement of the relay nodes, and optimal number of hops for multihop DF relaying which minimize their outage probability.
    No preview · Article · Nov 2013 · IEEE Communications Letters
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    ABSTRACT: To determine the capacity of distributed wireless networks (i.e., ad hoc networks), the random access transport capacity was proposed as the average maximum rate of successful end-to-end transmission in the distance. In this article, we consider the random access transport capacity for multihop relaying to find the end-to-end throughput of a wireless ad hoc network, where each node relays the signal using an amplify-and-forward (AF) strategy. In particular, we analyze the exact outage probability for multihop AF relaying in the presence of both co-channel interference and thermal noise, where interferers are spatially distributed following a Poisson distribution. In our numerical results, it is observed that the maximum random access transport capacity is achieved at a specific spatial density of transmitting nodes due to the throughput-reliability tradeoff as the number of transmitting nodes (=interferers) increases. We compute the optimal spatial density of transmitting nodes that maximize their random access transport capacity. As a result, we can obtain the actual random access transport capacity of multihop AF relaying and predict the maximum number of transmitting nodes per unit area to maximize their performance.
    Preview · Article · Apr 2013 · EURASIP Journal on Wireless Communications and Networking
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    ABSTRACT: In this paper, a decode-and-forward cooperative interference-limited multiple relay network is considered. An efficient relay selection strategy and its performance analysis are proposed, where only the relay nodes are affected by multiple interferences. In the proposed relay selection scheme, the selected relay is not always used, depending on the power of interferences and the channel state information of all links, while the direct path between source and destination is always used. For analytical tractability the distribution of interference-limited channel is approximated as an exponential distribution with high accuracy. Analysis of cooperative networks with interference-limited relays can be performed using the approximate exponential distribution by the same methods which have been used without interferences. We derive the bit error probability and outage probability of the proposed opportunistic max-min relay selection (OMRS) scheme in independent non-identically distributed Rayleigh fading channels. Numerical results present the superiority of OMRS over the conventional relay selection scheme which always uses the selected relay path. The exactness of the approximate analysis for interference-limited relays is also shown in numerical results.
    No preview · Article · Jan 2013 · Wireless Personal Communications
  • Sung-Il Kim · Jun Heo
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    ABSTRACT: In this paper, we investigate secure communication in two-hop cooperative relay network with physical layer network coding (PNC). By sending a jamming signal from the destination and exploiting the PNC at the relay, the relay decodes the exclusive-OR (XOR) performed message of the source message and the jamming. This process acts as the encryption of the source message at the relay with a random jamming sequence which can be subtracted only at the destination, so that it prevents the eavesdropper from intercepting the message. We derive the outage probability of the secure scheme with PNC and compare the performance with the cooperative scheme without jamming.
    No preview · Conference Paper · Jan 2013
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    ABSTRACT: In this paper, we propose a new power optimization and transmission period selection scheme for device-to-device (D2D) communication as an underlay to cellular networks. We show that the proposed scheme can achieve performance gain by flexibly allocating transmission power based on channel state information (CSI) and significantly increase reliability by selecting a transmission period.
    No preview · Conference Paper · Jan 2013
  • Sungsik Yoon · Jun Heo
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    ABSTRACT: In this paper, we introduce a new error correcting protocol in quantum key distribution. With this method, leakage information during the information reconciliation is reduced and a longer key can be obtained. In order to correct errors on the quantum key, we apply the turbo codes and transmit the parity information over the quantum channel. We compare loss rate of the proposed information reconciliation method with a conventional scheme in quantum key distribution.
    No preview · Conference Paper · Jan 2013
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    ABSTRACT: This paper presents an improved data hiding technique based on BCH (n,k,t ) coding. The proposed embedder hides data into a block of input data by modifying some coefficients in the block in order to null the syndrome. The proposed embedder can hide data with less computational time and less storage capacity compared to the existing methods. The complexity of the proposed method is linear while that of other methods are exponential for any block size n. Thus, it is easy to extend this method to a large n. The BCH syndrome coding for steganography is now viable ascribed to the reduced complexity and its simplicity of the proposed embedder.
    No preview · Article · Dec 2012 · IEEE Transactions on Information Theory
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    ABSTRACT: Codeword stabilized quantum codes provide a unified approach to constructing quantum error-correcting codes, including both additive and non-additive quantum codes. Standard codeword stabilized quantum codes encode quantum information into subspaces. The more general notion of encoding quantum information into a subsystem is known as an operator (or subsystem) quantum error correcting code. Most operator codes studied to date are based in the usual stabilizer formalism. We introduce operator quantum codes based on the codeword stabilized quantum code framework. Based on the necessary and sufficient conditions for operator quantum error correction, we derive a error correction condition for operator codeword stabilized quantum codes. Based on this condition, the word operators of a operator codeword stabilized quantum code are constructed from a set of classical binary errors induced by generators of the gauge group. We use this scheme to construct examples of both additive and non-additive codes that encode quantum information into a subsystem.
    Full-text · Article · Aug 2012 · Physical Review A
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    ABSTRACT: In this paper we design an irregular low-density parity-check (LDPC) code for multiple-input multiple-output (MIMO) systems, using a simple extrinsic information transfer (EXIT) chart method. The MIMO systems considered are the optimal maximum a posteriori probability (MAP) detector and the suboptimal minimum mean square error soft-interference cancellation (MMSE-SIC) detector. The MIMO detector and the LDPC decoder exchange soft information and form a turbo iterative receiver. The EXIT charts are used to obtain the edge degree distribution of the irregular LDPC code which is optimized for the MIMO detector. It is shown that the performance of the designed LDPC code is better than that of conventional LDPC code which was optimized for either the Additive White Gaussian Noise (AWGN) channel or the MIMO channel without an explicit consideration of the given detector structure. KeywordsLow-density parity-check (LDPC) codes–Multi-input multi-output (MIMO) detection–Iterative decoding–EXIT chart
    Full-text · Article · Feb 2012 · Wireless Personal Communications
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    ABSTRACT: We investigate a performance of cooperative relaying in the device-to-device (D2D) systems underlaying cellular networks while considering power constraints on the average received-interference at the evolved NodeB (eNB). Specifically, we consider the D2D communication assisted by relays using multihop decode-and-forward (DF) strategy in interference existing circumstances. In this paper, we obtain exact closed-form expression for the CDF and the PDF of the received Signal-to-Interference-plus-noise ratio (SINR) at the end user over Rayleigh flat fading channel. The end-to-end performance is investigated in terms of the maximum ergodic capacity, and the outage probability. Simulation results follow to show the performance of the system in the various propagation conditions.
    No preview · Conference Paper · Jan 2012
  • Sung-Il Kim · Jun Heo
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    ABSTRACT: This paper investigates the outage performance of an amplify-and-forward (AF) relay network with varying number of relays (RN-VR). In the previous works for the analysis of multi-relay networks, the number of available relays is always assumed to be fixed. Thus, the performance and diversity of the relay network is determined by the assumed number of available relays. However, under some practical cooperative system where many users in neighboring region share a restricted number of relays, the number of available relays may change due to the preoccupied relays by other users. Therefore, the performance and diversity of the relay networks cannot be represented as the previous analysis and, thus, a different investigation of this model is needed in this case. To investigate the suggested cooperative system, occupancy of each relay is modeled as a continuous time Markov on-off process to represent the varying number of relays and provide analytical insight. Based on this theoretical approach, we explore the outage performance of an AF relay network which is called RN-VR in a practical manner.
    No preview · Conference Paper · Jan 2012
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    ABSTRACT: To account for randomly distributed nodes in a wireless ad hoc network, the transmission capacity is defined as the number of successful transmissions taking place in the network per unit area under an outage constraint. In this paper, we analyze the transmission capacity for dual-hop relaying in a wireless ad hoc network in the presence of both cochannel interference and thermal noise, where interferers are spatially distributed following a Poisson distribution. Specifically, we first present the exact outage probability for amplify-and-forward and decode-and-forward protocols in a Poisson field of interferers without neglecting noise at all nodes. We then derive the transmission capacity of such networks, which determines the maximum allowable density of transmitting nodes for each relay strategy at a specified outage probability and data rate. Numerical results demonstrate that the dual-hop relaying is still beneficial in terms of the transmission capacity in wireless ad hoc Poisson networks.
    Preview · Article · Jan 2012 · EURASIP Journal on Wireless Communications and Networking

Publication Stats

378 Citations
48.45 Total Impact Points

Institutions

  • 2008-2015
    • Korea University
      • Department of Electrical Engineering
      Sŏul, Seoul, South Korea
    • LG Electronics
      Sŏul, Seoul, South Korea
  • 2004-2014
    • Konkuk University
      • Department of Electronics Engineering
      Sŏul, Seoul, South Korea
  • 2006
    • Dankook University
      Eidō, North Chungcheong, South Korea
  • 2000-2002
    • University of Southern California
      • Department of Electrical Engineering
      Los Angeles, California, United States