Jun Heo

Korea University, Sŏul, Seoul, South Korea

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Publications (57)27.49 Total impact

  • 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.
    Wireless Personal Communications 08/2014; 77(3). · 0.43 Impact Factor
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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.
    Wireless Personal Communications 06/2014; · 0.43 Impact Factor
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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.
    Wireless Personal Communications 01/2014; 75(4). · 0.43 Impact Factor
  • IEICE Transactions on Communications 01/2014; E97.B(6):1148-1156. · 0.31 Impact Factor
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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.
    11/2013;
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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.
    IEEE Communications Letters 01/2013; 17(11):2029-2032. · 1.16 Impact Factor
  • 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.
    ICT Convergence (ICTC), 2013 International Conference on; 01/2013
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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.
    ICT Convergence (ICTC), 2013 International Conference on; 01/2013
  • Sung-Il Kim, Saejoon Kim, Joon Tae Kim, Jun Heo
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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.
    Wireless Personal Communications 01/2013; 68(2). · 0.43 Impact Factor
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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.
    Physical Review A 08/2012; 86(4). · 3.04 Impact Factor
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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
    Wireless Personal Communications 02/2012; 62(4):923-936. · 0.43 Impact Factor
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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.
    Information Theory and its Applications (ISITA), 2012 International Symposium on; 01/2012
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    ABSTRACT: To account for randomly distributed nodes in a wireless ad hoc network, the random access transport capacity is defined as the average maximum rate of successful end-to-end transmission over some distance. In this paper, we consider a random access transport capacity for a dual-hop relaying to find the end-to-end throughput of wireless ad hoc network, where each node relays using Amplify-and-Forward (AF) strategy. In particular, we also present the exact outage probability for dualhop AF relaying in the presence of both co-channel interference and thermal noise, where interferers are spatially distributed following a Poisson distribution. Intriguingly, even though transmitting nodes increase, numerical results demonstrate that the overall throughput of dual-hop AF relaying decreases due to interference. Moreover, it is noted that the dual-hop AF relaying is still beneficial in terms of the random access transport capacity in wireless ad hoc networks.
    01/2012;
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    ABSTRACT: In this paper, we consider an improved transmission scheme for HDTV broadcasting services in Europe. We investigate the Forward Error Correction (FEC) algorithm in DVB-T2 standard systems and propose a new algorithm to improve the performance of the FEC scheme. The FEC of DVB-T2 transmission system is serially concatenated binary BCH code and binary Low-Density Parity Check Code (LDPC code). As we replace binary BCH code by Block Turbo Code (BTC) which is good for soft decision iterative decoding, we examine the performance enhancement by lowering the error floor. Thus we suggest BTC and LDPC concatenation for 3D HDTV transmission system and present the improved performance by Monte Carlo simulation.
    01/2012;
  • 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.
    Personal Indoor and Mobile Radio Communications (PIMRC), 2012 IEEE 23rd International Symposium on; 01/2012
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    ABSTRACT: In this letter, the exact form of the outage probability for opportunistic amplify-and-forward (AF) partial relay selection scheme in interference-limited environment is derived. It is assumed that multiple interferers affect only on the relays due to the multicell environment of wireless networks. Analysis in this paper can be an efficient technique for investigating the effect of interference in cooperative AF relaying on the outage probability. We confirm that our analytical results match the simulation results perfectly on all the ranges of signal-to-noise ratio (SNR).
    IEEE Communications Letters 12/2011; 15:1281-1283. · 1.16 Impact Factor
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    ABSTRACT: Entangled qubit can increase the capacity of quantum error correcting codes based on stabilizer codes. In addition, by using entanglement quantum stabilizer codes can be construct from classical linear codes that do not satisfy the dual-containing constraint. We show that it is possible to construct both additive and non-additive quantum codes using the codeword stabilized quantum code framework. Nonadditive codes may offer improved performance over the more common sta- bilizer codes. Like other entanglement-assisted codes, the encoding procedure acts only the qubits on Alice's side, and only these qubits are assumed to pass through the channel. However, errors the codeword stabilized quantum code framework gives rise to effective Z errors on Bob side. We use this scheme to construct new entanglement-assisted non-additive quantum codes, in particular, ((5,16,2;1)) and ((7,4,5;4)) codes.
    Physical Review A 09/2011; · 3.04 Impact Factor
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    ABSTRACT: This paper presents cooperative spectrum sensing techniques for cognitive radio (CR) systems. The spectrum sensing detects the presence of a primary user (service) on an associated spectrum. The accuracy of spectrum sensing depends on both sensing time and number of sensing nodes (i.e. secondary users) participating in the sensing process. We derive optimal number of secondary users for cooperative spectrum sensing to minimize spectrum detection error probability and optimal spectrum sensing time to maximize data transmission throughput. A system model which consists of a primary TV spectrum and multiple Wi-Fi secondary users is considered. The proposed CR scheme can solve recent spectrum shortage problem in Wi-Fi networks due to traffic explosion by smart phones. We propose K-out-of-N-rule which is the most efficient cooperative sensing rule by analytical and numerical results.
    IEEE Transactions on Consumer Electronics 01/2011; 57(1):62-67. · 1.09 Impact Factor
  • Sung-il Kim, Jun Heo
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    ABSTRACT: The outage probability of dual-hop amplify-and- forward (AF) relaying scheme with partial relay selection is derived when the multiple interferences affect on the relay nodes. In contrast to the previous works, we focus on analyzing the effect of multiple interferences which make the transmission channel degraded. Following the partial relay selection policy, the best source to relay path is selected based on the comparisons of signal-to-interference and noise ratio (SINR) among all source to relay paths. An exact expression of outage probability is presented and simulation results are also presented for the validity of the analytical result. This result shows the effect of multiple interferences on cooperative AF relaying system in multicell environment.
    Proceedings of the 73rd IEEE Vehicular Technology Conference, VTC Spring 2011, 15-18 May 2011, Budapest, Hungary; 01/2011
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    ABSTRACT: This paper presents generalization and application for the conventional SISO decoding algorithm of Block Turbo Codes. R. M. Pyndiah suggested an iterative SISO decoding algorithm for Product Codes, two-dimensionally combined linear block codes, on AWGN channel. It wascalled Block Turbo Codes. Based on decision of Chase algorithm which is SIHO decoding method, SISO decoder for BTC computes soft decision information and transfers the information to next decoder for iterative decoding. Block Turbo Codes show Shannon limit approaching performance with a little iteration at high code rate on AWGN channel. In this paper we generalize the conventional decoding algorithm of Block Turbo Codes, under BPSK modulation and AWGN channel transmission assumption, to the LLR value based algorithm and suggest an application example such as concatenated structure of LDPC codes and Block Turbo Codes.
    Journal of Broadcast Engineering. 01/2011; 16(6).