Single-carrier Frequency-division Multiplexing Research Articles

Novel D2D resource partitioning and allocation schemes for SC‐FDMA‐based public safety systems

AbstractDevice‐to‐device (D2D) communication is essential for the provision of the broadcasting service for public safety (PS) terminals in out‐of‐network coverage. A sensing‐based resource‐allocation scheme is desirable, rather than a random approach, for next‐generation, PS systems, so that higher data rates and a massive connectivity can be supported. The half‐duplex and resource collisions are the main design constraints, especially for the single carrier frequency division multiplexing (SC‐FDMA)‐based D2D broadcast system. A novel resource‐allocation scheme is proposed in this paper, whereby the resource partitions are managed adaptively based on sensing results. The system‐level evaluation and analysis results show that the proposed scheme significantly improves upon the overall network performance of the conventional scheme, especially with respect to the resource‐collision rate and the throughput. Copyright © 2016 John Wiley & Sons, Ltd.

Exploring the physical layer frontiers of cellular uplink: The Vienna LTE-A Uplink Simulator.

Communication systems in practice are subject to many technical/technological constraints and restrictions. Multiple input, multiple output (MIMO) processing in current wireless communications, as an example, mostly employs codebook-based pre-coding to save computational complexity at the transmitters and receivers. In such cases, closed form expressions for capacity or bit-error probability are often unattainable; effects of realistic signal processing algorithms on the performance of practical communication systems rather have to be studied in simulation environments. The Vienna LTE-A Uplink Simulator is a 3GPP LTE-A standard compliant MATLAB-based link level simulator that is publicly available under an academic use license, facilitating reproducible evaluations of signal processing algorithms and transceiver designs in wireless communications. This paper reviews research results that have been obtained by means of the Vienna LTE-A Uplink Simulator, highlights the effects of single-carrier frequency-division multiplexing (as the distinguishing feature to LTE-A downlink), extends known link adaptation concepts to uplink transmission, shows the implications of the uplink pilot pattern for gathering channel state information at the receiver and completes with possible future research directions.

Coherent Optical Interleaved SC-FDM Uplink Scheme for Long-Reach Passive Optical Network

In this paper, we propose a coherent optical interleaved single-carrier frequency-division multiplexing (CO-I-SC-FDM) uplink scheme for the long-reach passive optical network (LR-PON). I-SC-FDM is a modified form of orthogonal frequency-division multiplexing (OFDM) with low computational complexity and low peak-to-average power ratio (PAPR). By designing a simple encoding structure, the computational complexity of the transmitter can be reduced from O(Nlog 2 (N)) to O(N). At the probability of 10 -3 , the PAPR of the I-SC-FDM is about 10.7 dB lower than that of conventional OFDM for quadrature phase-shift keying (QPSK) modulation. We experimentally demonstrate a 10-Gb/s CO-I-SC-FDM uplink scheme over 100-km standard single-mode fiber with 1:128-way passive splitter for LR-PON. In the conventional CO-OFDM uplink scheme, the splitting ratio is only 1:64. The proposed scheme shows great potential for application in access and metro networks.

다이버시티 기법을 이용한 서해에서의 음선 모델기반 수중음향통신 시스템

본 논문은 서해의 수중음향 통신 네트워크의 물리계층에 적합한 수중음향통신 시스템을 제안한다. 서해정점의 해양 관측정보와 Bellhop 음선 추적프로그램을 이용하여 서해정점의 수중 채널 모델을 구하고 이 수중 채널 모델을 이용하여 통신 변수들을 산출하고 다이버시티 기법이 응용된 CDMA(Code Division Multiple Access)와 SC-FDM(Single Carrier-Frequency Division Multiplexing) 전송방식을 이용한 음향 통신시스템을 설계한다. 설계된 통신시스템의 성능을 검증하기 위해 여러 통신환경에 대한 비트 오류율과 데이터 전송률을 연산하고 이로부터 서해안에서 긴 지연시간을 가지는 수중 채널과 낮은 Eb/No에서 사용가능한 수중 음향통신 기법을 제안한다. This paper proposes an adequate UWA (Underwater Acoustic) communication system of underwater communication network in the Yellow Sea. UWA channel is obtained from Bellhop ray tracing method with Yellow Sea environments. Based on this channel, communication parameters for CDMA (Code Division Multiple Access) and SC-FDM (Single Carrier-Frequency Division Multiplexing) using diversity techniques are calculated. In order to prove the proposed methods, BER (Bit Error Rate) and data rate are obtained using computer simulations and the adequate communication system for long rms delay spread and low Eb/No environments is proposed from the simulation.

Performance Improvement of IFDMA and LFDMA using NCT Technique

Orthogonal Frequency Division Multiplexing (OFDM) is a well-known modulation technique for transmission of large amount of digital data with high data rate in both wired and wireless communication systems. High peak-to-average power ratio (PAPR) is the main problem of OFDM system which can be improved by using single carrier frequency division multiple access (SC-FDMA) technique. A new scheme using LFDMA and IFDMA technique is proposed for further reducing the peak-to-average power ratio (PAPR). It transforms the SC-FDMA signal by properly choosing the transform parameters for achieving a favorable tradeoff between PAPR reduction and bit error rate (BER) performances. The simulation results show better performance of the proposed scheme than the existing technique. In this paper, we have improved the PAPR performance of single carrier frequency division multiplexing (SC-FDMA) using LFDMA and IFDMA with and without pulse shaping.

상향링크 SIMO 시스템에서 공간 및 주파수 다이버시티 컴바이닝 순서에 따른 SC-FDMA 성능 분석

We investigate BER performance according to the order of spatial and frequency diversity combining in uplink SC-FDMA of SIMO systems. It is found that frequency diversity combining (FDC) after spatial diversity combining (SDC) is better than the reverse order combing in all SNR (Signal to Noise Ratio) range. Also, it is shown that FDC after SDC requires less computational complexity than the reverse order combining. ※ 본 연구는 2014년도 정부(교육부)의 재원으로 한국연구재단의 기초연구사업 지원을 받아 수행된 것임 (2012R1A1A4A01015628) ※ 본 논문은 교육부 및 한국연구재단의 BK21 플러스 사업 (ICT기반 스마트기기 창의인재양성 사업팀)으로 지원된 연구임 (관리번호 21466) First Author : Yeungnam University Dept. of Information Communications Engineering, jinh37@ynu.ac.kr, 학생회원 ° Corresponding Author : Yeungnam University Dept. of Information Communications Engineering, gonew@ynu.ac.kr, 종신회원 논문번호:KICS2014-11-460, Received November 17, 2014; Revised January 28, 2015; Accepted March 9, 2015 I. 서 론 다중 수신안테나 시스템에 접목된 SC-FDMA (Single Carrier Frequency Division Multiplexing Access)는 수신안테나에 의한 공간 다이버시티 이득 과 DFT, IDFT 연산에 의한 주파수 다이버시티 이득 을 가진다 . MIMO (Multiple Input Multiple Output) 환경에서주파수 다이버시티를 활용하여 성능 을 분석한 연구가 있었으며 , 특히, 신호의 성능을 향 상시키기 위해 두 개 이상의 다이버시티 이득을 활용 한 연구들이 진행되어 왔다 . 참고문헌 [5]에서는 단계별 시스템의 공간 다이버 시티 컴바이닝 (Spatial Diversity Combining: SDC) 연산과 주파수 다이버시티 컴바이닝 (Frequency Diversity Combining: FDC) 연산에 각각 MRC 논문 / 상향링크 SIMO 시스템에서 공간 및 주파수 다이버시티 컴바이닝 순서에 따른 SC-FDMA 성능 분석 433 그림 1. 공간 다이버시티 컴바이닝과 주파수 다이버시티 컴바이닝이 존재할 때, 수신기 구조 Fig. 1. Receiver structure using spatial diversity combining and frequency diversity combining 그림 2. FDC 후 SDC를 수행한 수신기 구조 Fig. 2. Receiver structure performing SDC after FDC (Maximal Ratio Combining)와 MMSE (Minimum Mean Square Error)를 적용했을 때 최대의 성능을 가 지는 것을 확인했으며, 수신안테나 개수가 대략 6개 이상이면, 모든 SNR 영역에서 FDC 연산을 ZF (Zero Forcing)으로 했을 때의 성능이 MMSE로 했을 때의 성능을 대체할 수 있음을 분석하였다. 하지만, 다중 다이버시티 컴바이닝이 존재하는 환경에서 SDC와 FDC의 순서에 따른 시스템의 BER 성능을 분석하고 있지 않다. 즉, SDC 선행 후 FDC 수행 시스템 에 적 용한 다이버시티 컴바이닝 순서가 BER 성능을 향상 시키기 위한 가장 최적의 방법인지 확신할 수 없다. 그렇기 때문에 참고문헌 [5]와 동일한 환경에서 시스 템의 다이버시티 컴바이닝 순서에 따른 성능도 함께 분석하여 어떤 다이버시티 컴바이닝 순서를 가지는 시스템이 가장 최고의 성능을 가지는지 확인해볼 필 요가 있다. 본 논문에서는 상향링크 SIMO (Single Input Multiple Output) 시스템에서 공간 다이버시티 이득과 주파수 다이버시티 이득이 동시에 존재할 때, 다이버 시티 컴바이닝 순서가 SDC 선행 후 FDC 수행 시스 템 의 다이버시티 컴바이닝 순서와 반대인 시스템의 신호 처리 과정을 수식화하고, 계산량을 최소로 하면 서 성능을 최대로 하는 다이버시티 컴바이닝 순서는 SDC 선행 후 FDC 수행 시스템의 다이버시티 컴바 이닝 순서임을 결과로 도출한다. 본 논문의 구성은 다음과 같다. II절에서는 SDC 선행 후 FDC 수행 시스템 에서 다이버시티 컴바이 닝 순서를 바꾼 시스템의 신호 모형화를 반영한다. III 절에서는 시스템 모형화 결과와 BER 실험결과를 통 해 다이버시티 컴바이닝 순서에 따른 BER 성능을 분 석하고, SDC 선행 후 FDC 수행 시스템 의 다이버시 티 컴바이닝 순서가 BER 성능을 최대화하는 다이버 시티 컴바이닝 순서임을 확인한다. II. FDC를 선행하고 SDC를 수행하는 단계별 시스템 모형화 참고문헌 [5]에서는 단계별 시스템의 다이버시티 컴바이닝을 그림 1과 같이 SDC, FDC 순으로 가정하 고 시스템 모형화를 수행하였다. 본 논문에서는 단계 별 시스템의 다이버시티 컴바이닝 순서에 따른 성능 비교를 하기 위해서 먼저, 다이버시티 컴바이닝 순서 를 그림 1의 다이버시티 컴바이닝 순서와 반대인 그 림 2와 같이 설정하고 시스템을 모형화한다. 본 논문 에서 그림 1과 같이 SDC 선행 후 FDC 수행 시스템 을 S/F 시스템으로 표기하고, 그림 2와 같은 FDC 선 The Journal of Korean Institute of Communications and Information Sciences '15-03 Vol.40 No.03 434   

Optimization of 16-APSK by Maximizing Mutual Information Criteria in SC-FDMA Communication Systems

Single Carrier Frequency Division Multiplexing (SC-FDMA) scheme has been considered to be promising technology for the uplink of the 4G mobile communication systems. The main disadvantage of SC-FDMA is the high envelope fluctuation of signal resulting in a presence of nonlinear distortion in transmitted signal due to the transmitter high power amplifier (HPA). In order to improve the SC-FDMA performance, the 16-ary Amplitude Phase Shift Keying (16-APSK) is proposed as a base-band modulation scheme for SC-FDMA instead of conventional M-QAM. The different types of 16-APSK modulations will be investigated and positions of constellation points will be optimized according to maximizing Mutual Information (MI) criteria. For given value of SNR will be found optimal 16-APSK modulation and it will be proposed adaptive approach of 16-APSK modulation. The performance properties of adaptive approach of 16-APSK and 16-QAM based SC-FDMA transmission scheme will be illustrated using numerical results. The obtained results will show that optimized 16-APSK modulation in SC-FDMA transmitted system provide better performance than 16-QAM SC-FDMA system if the nonlinear model of HPA has to be assumed.

Experimental Demonstration of 1.2-Tb/s Optical PDM SCFDM Superchannel Multicasting by HNLF

Threefold 1.2-Tb/s optical polarization-division-multiplexing (PDM) single-carrier frequency-division-multiplexing (SCFDM) and orthogonal-frequency-division-multiplexing (OFDM) superchannel multicasting, utilizing multiple-pump four-wave mixing (FWM) by highly nonlinear fiber (HNLF), is proposed and experimentally demonstrated in this paper. The optical signal noise ratio (OSNR) penalties of the newly generated SCFDM and OFDM superchannels, at the bit error rate (BER) of 10-3, are 2.6 dB and 3.1 dB, respectively. Optimal pump power and signal power are also investigated for the two superchannels. The two superchannels have similar optimal pump power, whereas the SCFDM superchannel has higher optimal signal power due to the lower peak-to-average power ratio (PAPR).

Nonlinear performance of multi-granularity orthogonal transmission systems with frequency division multiplexing

Orthogonal transmission with frequency division multiplexing technique is investigated for next generation optical communication systems. Coherent optical orthogonal frequency division multiplexing (OFDM) and single-carrier frequency division multiplexing (SCFDM) schemes are compared in combination with polarization-division multiplexing quadrature phase shift keying (QPSK) or 16-QAM (quadrature amplitude modulation) formats. Multi-granularity transmission with flexible bandwidth can be realized through ultra-dense wavelength division multiplexing (UDWDM) based on the orthogonal technique. The system performance is numerically studied with special emphasis on transmission degradations due to fiber Kerr nonlinearity. The maximum reach and fiber capacity for different spectral efficiencies are investigated for systems with nonlinear propagation over uncompensated standard single-mode fiber (SSMF) links with lumped amplification.

Nonlinear Tolerant Spectrally-Efficient Transmission Using PDM 64-QAM Single Carrier FDM With Digital Pilot-Tone

We propose nonlinear tolerant single carrier frequency-division-multiplexing (SC-FDM) signal enhanced by digital pilot-tone for future high speed Ethernet transport like 400 G Ethernet. First, we discuss system configuration and the wavelength-division-multiplexed (WDM) transmission of SC-FDM signals employing polarization-division-multiplexed (PDM) 64-ary quadrature amplitude modulation (64-QAM). Next, we describe the long-haul transmission characteristics of 50 GHz-spaced 538 Gb/s × 7 ch WDM signals. We compare digital back-propagation (DBP) and digital pilot-tone for nonlinearity compensation and experimentally show that digital pilot-tone can effectively compensate the phase noise induced by inter-channel nonlinear effects with less computational complexity than DBP. Then we discuss a high-capacity transmission experiment employing 548 Gb/s PDM-64QAM SC-FDM; 102.3 Tb/s (224 × 548 Gb/s) C- and extended L-band WDM transmission is demonstrated over 240 km (3 × 80 km) of pure-silica-core fiber (PSCF) with all-Raman amplification. Thanks to the high nonlinear tolerance enhanced by pilot-tone, we can employ the 80 km repeater spacing used in conventional terrestrial systems. Assuming 20% forward error correction (FEC) overhead, a spectral efficiency of 9.1 b/s/Hz is achieved.

Experimental Demonstration of ROADM Functionality on an Optical SCFDM Superchannel

In this letter, we experimentally demonstrate reconfigurable optical add-drop multiplexer (ROADM) functionality on an orthogonal band multiplexed (OBM) single-carrier frequency-division-multiplexing (SCFDM) superchannel. As far as we know, this is the first time that ROADM functionality for individual band with frequency spacing of 10 GHz is realized.

Optical MIMO transmission for SCFDM-PON based on polarization interleaving

Orthogonal frequency division multiplexing-passive optical network (OFDM-PON) and single-carrier frequency division multiplexing (SCFDM)-PON are promising solutions for future high-speed PON-based access. A polarization division multiplexing scheme with direct detection is proposed for OFDM-PON to effectively reduce bandwidth requirements for components. However, the scheme strictly requires spectrum overlapping of two orthogonal sidebands and the 4×4 multi-input-multi-output (MIMO) algorithm to eliminate complex cross-polarization interference. In this letter, we propose a polarization interleaving (PI) approach that significantly reduces bandwidth requirements for optical and electrical components while achieving a high-flexibility and low-complexity MIMO algorithm. Downstream single sideband PI-SCFDM transmission is experimentally demonstrated.

On the Feasibility of Precoded Single User MIMO for LTE-A Uplink

The 3rd Generation Partnership Project (3GPP) is currently specifying the system requirements for Long Term Evolution - Advanced (LTE-A), having as a target peak data rates of 1 Gbit/s in local areas and 100 Mbit/s in wide areas. To meet these ambitious requirements for the uplink, multiple-input-multiple-output (MIMO) antenna techniques are expected to be deployed. In this paper, several channel-aware MIMO precoding techniques are presented. Specifically, precoded single user spatial multiplexing for both Orthogonal Frequency Division Multiplexing (OFDM) and Single Carrier Frequency Division Multiplexing (SCFDM) is studied, and its feasibility in a LTE-A uplink system is discussed. Particular emphasis is given to the limited feedback precoding, where a codebook generation method based on the Lloyd algorithm is proposed. Results show that, when full channel knowledge is available at both the transmitter and the receiver, precoding leads to a spectral efficiency gain up to 4 dB over open loop transmission; furthermore, OFDM slightly outperforms SC-FDM because of its higher robustness to the noise. Limited feedback precoding has been shown to be effective and consistently robust to the subcarrier grouping in a urban micro scenario. However, the performance is severely degraded in the blind precoding case, where transmitter and receiver compute the precoding matrix independently, due to the high sensitivity to the delay. Finally, the precoding operation over the SCFDM signal is shown to increase its Peak to Average Power Ratio (PAPR), thus reducing its advantage with respect to OFDM.