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Cooperative Hybrid-ARQ Protocols: Unified Frameworks for Protocol Analysis
Ilmu Byun,김광순 한국전자통신연구원 2011 ETRI Journal Vol.33 No.5
Cooperative hybrid-automatic repeat request (HARQ) protocols, which can exploit the spatial and temporal diversities, have been widely studied. The efficiency of cooperative HARQ protocols is higher than that of cooperative protocols because retransmissions are only performed when necessary. We classify cooperative HARQ protocols as three decode-and-forward-based HARQ (DF-HARQ) protocols and two amplified-and-forward-based HARQ (AF-HARQ) protocols. To compare these protocols and obtain the optimum parameters, two unified frameworks are developed for protocol analysis. Using the frameworks, we can evaluate and compare the maximum throughput and outage probabilities according to the SNR, the relay location, and the delay constraint. From the analysis we can see that the maximum achievable throughput of the DF-HARQ protocols can be much greater than that of the AF-HARQ protocols due to the incremental redundancy transmission at the relay.
Delay and Energy Constrained Random Access Transport Capacity
Ilmu Byun,Byung Hoon Ko,Ki Jun Jeon,Kwang Soon Kim IEEE 2014 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.13 No.8
<P>In this paper, we consider a delay and energy constrained wireless ad hoc network with node density of λ<SUB>n</SUB>, where a packet should be delivered to the destination within D(λ<SUB>n</SUB>) seconds using at most E(λ<SUB>n</SUB>) energy in joules while satisfying the target outage probability. The performance metric for analyzing the network is the delay and energy constrained random access transport capacity (DE-RATC), i.e., $C<SUB>ϵ</SUB>(D(λ<SUB>n</SUB>), E(λ<SUB>n</SUB>), which quantifies the maximum end-to-end distance weighted rate per unit area of a delay and energy constrained network using a random access protocol. It is shown that a slotted ALOHA protocol is order-optimal under any delay and energy constraints if equipped with additional features such as power control, multi-hop control, interference control, and rate control, and the delay and energy constraints can be divided into three regions according to the relation between the physical quantities due to the constraints and those due to the node density and network size. The three regions are the non-constrained (NC) region, where the DE-RATC is given by Θ(√λ<SUB>n</SUB>/logλ<SUB>n</SUB>); the delay-constrained (DC) region, where the DE-RATC depends only on the delay constraint as Θ(D(λ<SUB>n</SUB>); and the non-achievable (NA) region where a packet delivery under the given constraints is impossible. Also, it is shown that an arbitrary tradeoff between the rate of each source node and the number of source nodes can be achieved while keeping the optimal capacity scaling as long as λ<SUB>s</SUB>=Ω√λ<SUB>n</SUB>/logλ<SUB>n</SUB>, Dλ<SUB>n</SUB>))).</P>
Delay-Constrained Random Access Transport Capacity
Ilmu Byun,Andrews, Jeffrey G.,Kwang Soon Kim IEEE 2013 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.12 No.4
<P>In this paper, we consider delay-constrained wireless multi-hop ad hoc networks where a packet should be delivered to the destination within the maximum allowed delay while satisfying the target outage probability. The proposed performance metric for analyzing networks is the delay-constrained random access transport capacity (D-RATC), which quantifies the maximum end-to-end (e2e) link achievable rate per unit area of a delay-constrained network using a random access protocol. The scaling of the D-RATC is obtained for various slotted ALOHA (SA) protocols and it is shown that the SA protocol is order-optimal for delay-constrained random networks when interference control is used with an additional feature such as rate control or admission control. If interference control is not used, the SA protocol suffers from the negatively infinite scaling exponent except the case of using rate control where a finite but suboptimal scaling exponent may be achieved. Also, it is shown that multi-hop control does not affect the scaling exponent but just improves the D-RATC pre-constant.</P>
네트워크 부호화를 사용한 양방향 협력 ARQ 프로토콜의 성능 분석
변일무(Ilmu Byun),이형열(Hyung Yeol Lee),김광순(Kwang Soon Kim) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.10A
양방향 중계 채널 (two-way relay channel)은 2개의 단말이 중계기 (relay)의 도움을 받아 양방향의 정보를 주고 받는 협력 통신 (cooperative communication) 채널이다. 기존의 협력 통신에서는 중계기가 시간 또는 주파수 자원을 나누어 양방향으로 신호를 송신하지만, 네트워크 부호화 (network coding)를 사용한 양방향 중계 채널에서는 중계기가 동일 자원을 사용하여 두 단말로 신호를 동시에 송신하므로 기존 기법보다 높은 통신용량을 얻을 수 있다. 본 논문에서는 ARQ환경에서 네트워크 부호화를 사용한 협력통신 프로토콜을 보이고, 이를 스테이트 다이어그램 (state diagram) 을 이용하여 성능을 분석하였다. Two-way relay channel is a bidirectional cooperative communication channel that two terminals communicate each other with the help of a relay. In the previous cooperative communication schemes, a relay uses two divided resources for bidirectional transmission. When a network coding is used at a relay, the relay can transmit bidirec-tional data to two terminals simultaneously using one resource only. Thus the throughput of this scheme is greater than that of the previous scheme. In this paper, we showa two-way cooperative ARQ protocol using network coding and the throughput of this protocol is analyzed using a state diagram.
다중 사용자 MIMO-OFDMA 시스템에서 부분 궤환 정보를 이용한 비례적 공정 스케줄링의 성능 분석
강민규(Mingyu Kang),변일무(Ilmu Byun),박진배(Jin Bae Park),김광순(Kwang Soon Kim) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.6A
본 논문에서는 다중 사용자 다중 안테나-직교 주파수 분할 다중 접속 방식 (MIMO-OFDMA) 시스템에서 부분 궤환 정보를 이용한 정규화된 신호 대 잡음비 기반 비례적 공정 스케줄링 (normalized SNR based proportional fair scheduling, NSNR-PFS)을 수행할 경우의 시스템 성능에 대하여 분석하였다. 선택적 부분 채널 품질 정보 궤환 기법 (selective partial channel quality information feedback scheme, SPCQI)이 사용되었을 경우의 하향 링크 채널 용량의 정확한 식을 유도하고, 그것의 점근적 특성을 분석하였다. 이론적 성능 분석과 모의 실험을 통하여 사용자의 수와 상관없이 한정된 평균 궤환량만을 이용하여 최적의 하향 링크 채널 용량 증가율을 얻을 수 있음을 보였다. In this paper, we analyze the performance of normalized SNR based proportional fair scheduling with partial feedback information for multiuser MIMO-OFDMA systems. The closed form expression on the downlink capacity of the selective partial CQI feedback scheme is derived and its asymptotic behavior is investigated. From the performance analysis and numerical results, it is found that the optimal growth rate of downlink capacity can be achieved with bounded average feedback overhead irrespective of the number of users.