Topological Interference Management With Reconfigurable Antennas

Yang, Heecheol,Naderializadeh, Navid,Avestimehr, A. Salman,Lee, Jungwoo Institute of Electrical and Electronics Engineers 2017 IEEE Transactions on Communications Vol. No.

<P>We study the symmetric degrees-of-freedom (DoF) of partially connected interference networks under linear coding strategies without channel state information at the transmitters beyond topology. We assume that the receivers are equipped with reconfigurable antennas that can switch among their preset modes. In such a network setting, we characterize the class of network topologies in which half linear symmetric DoF is achievable. Moreover, we derive two general upper bounds on the linear symmetric DoF for arbitrary network topologies. We also demonstrate the tightness of our bounds for the class of network topologies in which all the transmitters in the network have at most two co-interferers.</P>

Hierarchical Blind Interference Alignment Over Interference Networks With Finite Coherence Time

Heecheol Yang,Wonjae Shin,Jungwoo Lee IEEE 2016 IEEE transactions on signal processing Vol.64 No.5

<P>We investigate a blind interference alignment (BIA) scheme through staggered antenna switching over various interference networks (e.g., broadcast channel, interference channel, and cellular networks) with realistic channel assumptions. In existing BIA, the coherence time of channel is assumed to be long enough, but that may not always be true in realistic scenarios. Therefore, we propose a dynamic supersymbol design method which can construct a supersymbol with limited symbol extension that is determined by the coherence time of channel. It is demonstrated that the supersymbol block length can be reduced significantly by aligning interferences in a hierarchical manner, referred to as hierarchical BIA. The key idea of hierarchical BIA is to align interferences in groups and to use the same supersymbol structure between groups, producing aligned inter-group interferences without inner-group interference. Consequently, it is observed that with a given coherence time the proposed dynamic supersymbol design that exploits hierarchical BIA achieves higher degrees of freedom than the conventional method.</P>

Degrees of Freedom for MIMO Z-Interference Channels with Reconfigurable Antennas in the Absence of CSIT

Heecheol Yang(양희철),Jungwoo Lee(이정우) 한국통신학회 2017 韓國通信學會論文誌 Vol.42 No.2

Linear Degrees of Freedom for $K$ -user MISO Interference Channels With Blind Interference Alignment

Yang, Heecheol,Shin, Wonjae,Lee, Jungwoo IEEE 2017 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.16 No.3

<P>In this paper, we characterize the degrees of freedom (DoF) for K-user M x 1 multiple-input single-output interference channels with reconfigurable antennas, which have N-preset modes at the receivers, assuming linear coding strategies in the absence of channel state information at the transmitters, i.e., blind interference alignment. Our linear DoF converse builds on the lemma that if a set of transmit symbols is aligned at their common unintended receivers, those symbols must have independent signal subspace at their corresponding receivers. This lemma arises from the inherent feature that channel state's changing patterns of the links towards the same receiver are always identical, assuming that the coherence time of the channel is long enough. We derive an upper bound for the linear sum DoF, and propose an achievable scheme that exactly achieves the linear sum DoF upper bound when both of the n*/M = R-1 and MK/n* = R-2 are integers, where n* denotes the optimal number of preset modes out of N preset modes. For the other cases, where either R-1 or R-2 is not an integer, we only give some guidelines how the interfering signals are aligned at the receivers to achieve the upper bound. As an extension, we also show the linear sum DoF upper bound for downlink/uplink cellular networks.</P>

Simultaneous multiplexed detection of exosomal biomarkers for cancer diagnosis

Heecheol YANG,Seongcheol CHO,Won Jong RHEE 한국생물공학회 2019 한국생물공학회 학술대회 Vol.2019 No.10

Linear Degrees of Freedom of Full-Duplex Cellular Networks With Reconfigurable Antennas

Yang, Heecheol,Shin, Wonjae,Lee, Jungwoo IEEE 2017 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.16 No.11

<P>In this paper, we characterize the linear degrees of freedom (DoF) of a cellular network in which the base station (BS) operates in a full-duplex (FD) mode and the users operate in a half-duplex mode. We assume that the BS and the users are equipped with reconfigurable antennas which can be switched between their preset modes. We consider two practical scenarios for different assumptions on channel state information at the transmit sides (CSIT), referred to as no CSIT and partial CSIT models. To derive the inner-bounds for two scenarios, we propose a new achievable scheme which enables interference alignment between uplink and downlink interference signals at each user via preset mode switching of reconfigurable antennas. The key concept of our scheme is to align the interference signals of uplink transmission at the downlink users, through the identical preset mode pattern over the multiple of downlink transmission periods and silence periods of the BS. We also develop an outer-bound on the linear sum DoF of the cellular network for the no CSIT model, which matches up with the inner-bound. Moreover, we also provide a natural variant of the proposed scheme when considering residual self-interference at the FD BS, which can alleviate the shortcoming of the existing self-interference cancellation techniques.</P>

연시조 『매화사』의 세 구조 연구

양희철(Yang Heecheol) 한국언어문학회 2010 한국언어문학 Vol.74 No.-

This study lookd upon three structures in the linked Si-Jo Maehwasa written by Ahn Min-young in the aspect of deviant stylistics. The result of this study is as follow; 1. There are two symmetrical expression(1, 2) that are able to help us understanding the sequential and the symmetrical structure in the linked Si-Jo Maehwasa. 2. As the result to examine the symmetrical expressions(1, 2) and the other expressions, we understood the sequential and symmetrical structure in the background time of the linked Si-Jo Maehwasa. The sequential and symmetrical structure is [the former time than the former time before the dust(the first unit)―the former time before the dust(the second unit)―the early dust(the third unit)―the middle dust(the fourth unit)―the latter dust(the fifth unit)―the later time after the dust(the sixth unit)―the later time than the later time after the dust(the seventh unit)]. 3. There are three symmetrical expression(3, 4, 5) and a deviant expression(1) that are able to help us understanding the symmetrical structure in the 2nd-6th units of the linked Si-Jo Maehwasa. 4. As the result to examine the symmetrical expressions(1-5), the deviant expression(1), and the other expressions, we understood the symmetrical structure that is the combination of the climactic structure and the anti-climactic structure in the 2nd-6th units of the linked Si-Jo Maehwasa. 5. There are seven deviant expression(2-8) that are able to help us understanding the logical structure in the linked Si-Jo Maehwasa. 6. As the result to examine the symmetrical expressions(1-5), the deviant expressions(1-8), and the other expressions, we understood the logical structure that is the combination of the introduction(the 1st unit), the development(the 2nd-6th unit), the turn(the 7th unit), and the conclusion(the 8th unit) in the linked Si-Jo Maehwasa. 7. Because the writer used the symmetrical expressions, the climactic structure, the anti-climactic structure, the symmetrical structure, and the repetition of the material(the flower tree 매화) etc, many repetitions of the similar words are discovered in the linked Si-Jo Maehwasa. We think that the result of this study will be able to give a significant influence on the study of the subject/meaning and the aesthetics in the linked Si-Jo Maehwasa.

향찰과 이두 ‘將來’의 연구 - ‘將’과 ‘來’의 음훈을 살린 해독들의 변증

양희철(Yang Heecheol) 한국언어문학회 2008 한국언어문학 Vol.66 No.-

  This study, in four aspects, demonstrated the preceding decoding to two character(將來) using the meaning and the sound of two characters(將來) in Hyangchal and Idu. First is the aspect of the meaning and the sound of two characters(將來), second is grammatical aspect, third is the aspect of the context, fourth is the comparative aspect of poetic word to translated poetic word. The result of this study is as follow;<BR>  1. The conjunctive ending and the stem(-어/아/여 오-), in the decoding of the Hyangchal/Idu(-將來-), are grounded in the meanings of two characters[將(=而)來].<BR>  2. The linking of the morphemes, in the words involving the Hyangchal/Idu(-將來-), is grammatical, in that the conjunctive ending(-어/아/여) is located at the back of the stems(造-, 爲-, 修-, 煎-) and stem+prefinal-endings(數+於-), in that the long sound mark or the mark confirming the preceding vowel(-어) is located at the back of adverb(只:그저), in that the stem(오-) is located at the forepart of the latter stem(-出-) in a compound stem, prefinal-endings(-臥-, -賜-), and engings(-尸, -呑隱).<BR>  3. The conjunctive ending and the stem(-어/아/여 오-), in the decoding of the Hyangchal/Idu(-將來-), are coincident with the contexts of the poems and the article involving the Hyangchal/Idu(-將來-).<BR>  4. The conjunctive ending and the stem(-어/아/여 오-), in the decoding of the Hyangchal/Idu[-將(=而)來-) involved in the two characters[造將(=而)來- and 修將(=而)來-], are coincident with the conjunctive ending and the stem(-어/아/여 오-), in the decoding of the words[(= 而)來-) involved in two phrases[成(而)來- and 修(而)來] of the translated poems<BR>  Putting the above accounts together, it seems incorrect the decoding[-려(-) or (-)오려(-)], that is decoded or followed by many decoders by now, and it seems correct the decoding(-어/아/여 오-), that was decoded or followed by a few decoders in past, and now is given but scant attention.

한중일의 도서관리 법제 비교 연구

양희철(YANG Heecheol) 대한국제법학회 2013 國際法學會論叢 Vol.58 No.4

데이터 프라이버시를 보장하는 부호화 분산 컴퓨팅 기법

양희철(Heecheol Yang),홍상우(Sangwoo Hong),이정우(Jungwoo Lee) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6

본 논문은 분산 컴퓨팅을 수행하는 서버(server)로부터 정보 이론적 데이터 프라이버시를 보장하는 부호화 분산 컴퓨팅 기법을 제안한다. 분산 컴퓨팅에서 느리게 연산을 처리하는 낙오 서버(straggler)의 영향을 줄이기 위해 연산량이 적은 다수의 연산 업무를 각 서버에 할당하는 환경을 가정하였다. 마스터(master)가 행렬 곱 연산을 수행하는 분산 컴퓨팅 시스템에서 데이터 프라이버시를 서버로부터 보장하기 위해 행렬 간 대칭성이 보장된 쿼리(query)를 생성하여 서버에 전송한다. 이를 통해 낙오 서버의 영향을 감소하면서 동시에 데이터 프라이버시를 보장할 수 있음을 밝혔다.