Showing papers on "Quadrature amplitude modulation published in 2011"
TL;DR: In this article, the performance of Nyquist-WDM Terabit superchannels implemented using polarization-multiplexed phase shift-keying based on 2 (PM-BPSK) and 4 (PM)-QPSK signal points was investigated through simulations.
Abstract: We investigated through simulations the performance of Nyquist-WDM Terabit superchannels implemented using polarization-multiplexed phase shift-keying based on 2 (PM-BPSK) and 4 (PM-QPSK) signal points or polarization-multiplexed quadrature amplitude modulation based on 8 (PM-8QAM) and 16 (PM-16QAM) signal points. Terabit superchannels are obtained through the aggregation of multiple subcarriers using the Nyquist-WDM technique, based on a tight spectral shaping of each subcarrier which allows very narrow spacing. We first studied the optimum transmitter/receiver filtering in a back-to-back configuration. Then we investigated the maximum reach for different spectral efficiencies, after nonlinear propagation over uncompensated links with lumped amplification. Performance for systems based on both standard single-mode fiber (SSMF) and large effective area non-zero dispersion-shifted fiber (NZDSF) has been analyzed. Assuming SSMF with 25-dB span loss, we found that PM-BPSK can reach 6480 km at a net capacity of 4 Tb/s across the C band. Conversely, PM-16QAM can deliver 27 Tb/s, but over 270 km only. Note that a lower span length, the use of Raman amplification and/or pure silica-core fibers (PSCFs) can significantly increase the maximum reach, but without changing the hierarchy among the performance of modulation formats. We also show that the maximum reachable distance is approximately 2/3 of the one achievable in linear propagation at the optimum launch power, regardless of the modulation format, spacing and fiber type. As additional results, we also verified that the optimum launch power per subcarrier linearly depends on the span loss, varies with the fiber type, but it is independent of the modulation format, and that the relationship between the maximum reachable distance and the span loss is almost linear.
545 citations
05 Jun 2011
TL;DR: Novel modulation techniques are proposed for coding and decoding information of the so-called messenger molecule concentration waves in nanonetworks that achieve high channel capacity values and exhibits more robustness against noise and requires less power.
Abstract: Communication via diffusion of molecules is an effective method for transporting information in nanonetworks. In this paper, novel modulation techniques called Concentration Shift Keying (CSK) and Molecule Shift Keying (MSK) are proposed for coding and decoding information of the so-called messenger molecule concentration waves in nanonetworks. The first technique, CSK, modulates the information via the variation in the concentration of the messenger molecules whereas MSK utilizes different types of messenger molecules to represent the information. Using simulation, the performance of these modulation techniques is evaluated in terms of susceptibility to noise and transmission power requirements. The new techniques achieve high channel capacity values, in particular, the MSK technique exhibits more robustness against noise and requires less power.
399 citations
01 Dec 2011
TL;DR: A modified technique is proposed which avoids bit error propagation whilst retaining the benefits of the concept and can lead to a decrease of the peak system power, which is highly beneficial in the context of optical wireless communication.
Abstract: A novel modulation technique coined SIM-OFDM was recently proposed. SIM-OFDM uses different frequency carrier states to convey information and leads to increased performance in comparison to conventional OFDM. Additionally, its innovative structure can lead to a decrease of the peak system power, which is highly beneficial in the context of optical wireless communication. One of the issues of the original SIM-OFDM scheme is a potential bit error propagation which could lead to significant burst errors. The current paper proposes a modified technique which avoids bit error propagation whilst retaining the benefits of the concept.
241 citations
18 Sep 2011
TL;DR: In this article, the effect of in-band crosstalk on several advanced optical modulation formats, including QPSK, 16-QAM, and 64 QAM, was quantified through simulations and experiments.
Abstract: We quantify, through simulations and experiments at 21.4 GBaud, the effect of in-band crosstalk on several advanced optical modulation formats, showing a 1-dB penalty at a bit-error ratio of 1×10−3 from a crosstalk of −18 dB, −24 dB, and −32 dB for QPSK, 16-QAM, and 64-QAM, respectively.
210 citations
TL;DR: 40-Gb/s W-band 16-QAM radio-over-fiber signal is optically synthesized using dual-polarization QPSK modulator and its wireless transmission within FEC limit is demonstrated with optical self-heterodyne detection and digital signal processing.
Abstract: The generation of a 40-Gb/s 16-QAM radio-over-fiber (RoF) signal and its demodulation of the wireless signal transmitted over free space of 30 mm in W-band (75-110 GHz) is demonstrated. The 16-QAM signal is generated by a coherent polarization synthesis method using a dual-polarization QPSK modulator. A combination of the simple RoF generation and the versatile digital receiver technique is suitable for the proposed coherent optical/wireless seamless network.
208 citations
TL;DR: The paper presents system considerations for wireless links in the 200-300-GHz range, discusses the design and performance of dedicated broadband transmit and receive MMICs, and presents link experiments.
Abstract: A wireless data link operating at a carrier frequency of 220 GHz is supporting a data rate of up to 25 Gbit/s in on-off-keyed PRBS as well as complex 256-QAM (quadrature amplitude modulation) transmission. The millimeter-wave transmit and receive frontends consist of active multi-functional millimeter-wave microwave integrated circuits (MMICs), realized in 50 nm mHEMT technology and packaged into split-block waveguide modules. The paper presents system considerations for wireless links in the 200-300-GHz range, discusses the design and performance of dedicated broadband transmit and receive MMICs, and presents link experiments. With an RF transmit power of -3.4-1.4 dBm in the IF frequency range from 0 to 20 GHz , a receiver conversion gain of better than -4.8 dB up to 270 GHz and an estimated noise figure of less than 7.5 dB at 220 GHz, a 231-1 PRBS with a data rate of up to 25 Gbit/s is transmitted over 50 cm and received with an eye diagram quality factor >;3 . At 10 Gbit/s, an uncorrected bit-error rate (BER) of 1.6·10-9 is measured over a distance of 2 m. A 256-QAM signal with approx. 14 Mbit/s is received with an uncorrected BER of 9.1·10-4.
207 citations
TL;DR: In this paper, a low-complexity intrachannel nonlinear compensator operating at the symbol rate is proposed based on the nonlinear perturbation predistortion for the dual-polarization quadrature phase-shift keying (DP-QPSK) systems.
Abstract: Intrachannel nonlinearity is considered a major distortion in high-capacity transmission systems particular for the case without inline optical chromatic dispersion compensation. In this paper, a low-complexity intrachannel nonlinear compensator operating at the symbol rate is proposed based on the nonlinear perturbation predistortion for the dual-polarization quadrature phase-shift keying (DP-QPSK) systems. Compared with the widely studied backpropagation algorithm, the proposed algorithm achieves comparable performance with significantly reduced complexity and halved sampling speed in digital signal processing and digital-to-analog converters. The proposed algorithm is demonstrated in a 43 Gb/s DP-QPSK transmission experiment over 1500 km. In addition to the experimental demonstration, numerical simulation verifies that the proposed algorithm is quite robust by tolerating significant uncertainties of link parameters and span-by-span inhomogeneity in the links.
205 citations
TL;DR: This paper proposes a novel Generalized Space-Time Shift Keying (G-STSK) architecture, which acts as a unified Multiple-Input Multiple-Output (MIMO) framework, based on the rationale that P out of Q dispersion matrices are selected and linearly combined in conjunction with the classic PSK/QAM modulation.
Abstract: In this paper, motivated by the recent concept of Spatial Modulation (SM), we propose a novel Generalized Space-Time Shift Keying (G-STSK) architecture, which acts as a unified Multiple-Input Multiple-Output (MIMO) framework. More specifically, our G-STSK scheme is based on the rationale that P out of Q dispersion matrices are selected and linearly combined in conjunction with the classic PSK/QAM modulation, where activating P out of Q dispersion matrices provides an implicit means of conveying information bits in addition to the classic modem. Due to its substantial flexibility, our G-STSK framework includes diverse MIMO arrangements, such as SM, Space-Shift Keying (SSK), Linear Dispersion Codes (LDCs), Space-Time Block Codes (STBCs) and Bell Lab's Layered Space-Time (BLAST) scheme. Hence it has the potential of subsuming all of them, when flexibly adapting a set of system parameters. Moreover, we also derive the Discrete-input Continuous-output Memoryless Channel (DCMC) capacity for our G-STSK scheme, which serves as the unified capacity limit, hence quantifying the capacity of the class of MIMO arrangements. Furthermore, EXtrinsic Information Transfer (EXIT) chart analysis is used for designing our G-STSK scheme and for characterizing its iterative decoding convergence.
160 citations
TL;DR: In this paper, the authors discuss the generation, wavelength-division-multiplexed (WDM) longhaul transmission, and coherent detection of 224-Gb/s PIMO 16-ary quadrature amplitude modulation (16-QAM) at a line rate of 28 Gbaud.
Abstract: We discuss the generation, wavelength-division-multiplexed (WDM) long-haul transmission, and coherent detection of 224-Gb/s polarization-division-multiplexed (PDM) 16-ary quadrature amplitude modulation (16-QAM) at a line rate of 28 Gbaud. We measure a required optical signal-to-noise ratio of 23.4 dB (0.1-nm reference bandwidth; 10-3 bit-error ratio), 3.4-dB off the theoretical limit. Using ultra-large-area fiber, we achieve 2000-km single-channel transmission. We also demonstrate 1200-km WDM transmission on a 50-GHz grid (4-b/s/Hz spectral efficiency), including three passes through a wavelength-selective switch.
149 citations
TL;DR: A special kind of APSK constellations with Gray mapping (Gray-APSK) is proposed, which provides considerable shaping gain compared with the QAM constellation with Gray maps ( Gray-QAM) in both independent and iterative demapping scenarios, as verified by average mutual information analysis and bit error rate simulations.
Abstract: Amplitude phase shift keying (APSK) constellation is superior to its quadrature amplitude modulation (QAM) counterpart from the mutual information point of view. However, due to the lack of Gray mapping, it introduces high independent demapping loss. In this letter, a special kind of APSK constellations with Gray mapping (Gray-APSK) is proposed, which provides considerable shaping gain compared with the QAM constellations with Gray mapping (Gray-QAM) in both independent and iterative demapping scenarios, as verified by average mutual information analysis and bit error rate simulations.
144 citations
TL;DR: In this paper, the authors report the successful transmission of 64 Tb/s capacity (640 ×107 Gb/S with 12.5 GHz channel spacing) over 320 km reach utilizing 8-THz of spectrum in the C+L -bands at a net spectral efficiency of 8 bit/s/Hz.
Abstract: We report the successful transmission of 64 Tb/s capacity (640 ×107 Gb/s with 12.5 GHz channel spacing) over 320 km reach utilizing 8-THz of spectrum in the C+L -bands at a net spectral efficiency of 8 bit/s/Hz. Such a result is accomplished by the use of raised-cosine pulse-shaped PDM-36QAM modulation, intradyne detection, both pre- and post-transmission digital equalization, and ultra-large-area fiber. We discuss in detail the digital modulation technology and signal processing algorithms used in the experiment, including a new two-stage, blind frequency-search-based frequency-offset estimation algorithm and a more computationally efficient carrier-phase recovery algorithm.
TL;DR: The results obtained confirm the effectiveness of the proposed technique with channels that exhibit significant frequency selectivity at the subchannel level and show a performance comparable with the optimum minimum mean-square-error equalizer, despite a significantly lower computational complexity.
Abstract: In this paper, the problem of channel equalization in filter bank multicarrier (FBMC) transmission based on the offset quadrature-amplitude modulation (OQAM) subcarrier modulation is addressed. Finite impulse response (FIR) per-subchannel equalizers are derived based on the frequency sampling (FS) approach, both for the single-input multiple-output (SIMO) receive diversity and the multiple-input multiple-output (MIMO) spatially multiplexed FBMC/OQAM systems. The FS design consists of computing the equalizer in the frequency domain at a number of frequency points within a subchannel bandwidth, and based on this, the coefficients of subcarrier-wise equalizers are derived. We evaluate the error rate performance and computational complexity of the proposed scheme for both antenna configurations and compare them with the SIMO/MIMO OFDM equalizers. The results obtained confirm the effectiveness of the proposed technique with channels that exhibit significant frequency selectivity at the subchannel level and show a performance comparable with the optimum minimum mean-square-error equalizer, despite a significantly lower computational complexity. The possibility of tolerating significant subchannel frequency selectivity gives more freedom in the multicarrier system parameterization. For example, it is possible to use significantly wider subcarrier spacing than what is feasible in OFDM, thus relieving various critical design constraints.
TL;DR: A 60 GHz quadrature PLL frequency synthesizer for the IEEE802.15.3c with wide tuning range and low phase noise is proposed, which is about 20 dB better than recently reported QPLLs and about 10 dB compared to differential PLLs operating at a similar frequency and at asimilar offset.
Abstract: This paper proposes a 60 GHz quadrature PLL frequency synthesizer for the IEEE802.15.3c with wide tuning range and low phase noise. The synthesizer is constructed using a 20 GHz PLL that is coupled with a Quadrature Injection Locked Oscillator (QILO) as a frequency tripler to generate the 60 GHz signal. The 20 GHz PLL generates a signal with a phase noise that is lower than -105 dBc/Hz using tail feedback to improve the phase noise while having a 17% tuning range. The proposed 60 GHz QILO uses a combination of parallel and tail injection to enhance the locking range by improving the QILO injection efficiency at the moment of injection and has a 12% tuning range. Both the 20 GHz PLL and the QILO were fabricated as separate chips using a 65 nm CMOS process and measurement results show a phase noise that is less than -95 dBc/Hz@1 MHz at 60 GHz while consuming 80 mW from a 1.2 V supply. To the author's knowledge this phase noise is about 20 dB better than recently reported QPLLs and about 10 dB compared to differential PLLs operating at a similar frequency and at a similar offset.
TL;DR: In this paper, the modulation formats for serial optical transmission of 100-Gbit/s and beyond are reviewed. And the main characteristics of modulation formats and application areas of transport technologies for future networks are discussed.
TL;DR: It is shown that the launch power maximizing capacity is independent of link length and modulation format, and the usable range of PM-QAM systems is discussed.
Abstract: Based on a recently introduced model of non-linear propagation, we propose analytical formulas for the capacity limit of polarization-multiplexed ultra-dense WDM uncompensated coherent optical systems at the Nyquist limit, assuming both lumped and ideally distributed amplification. According to these formulas, capacity fundamentally depends on the transmitted power spectral density and on the total optical WDM bandwidth, whereas it does not depend on symbol-rate. Also, capacity approximately decreases by 2 [bit/s/Hz] for every doubling of link length. We show examples of capacity calculations for specific ultra-long-haul links with different polarization-multiplexed (PM) constellations, i.e. ideal PM-Gaussian, PM-QPSK (quadrature-phase shift keying) and PM-QAM (quadrature amplitude modulation). We show that the launch power maximizing capacity is independent of link length and modulation format. We also discuss the usable range of PM-QAM systems and validate analysis with simulations.
TL;DR: A novel reduced-complexity near-optimal detection algorithm is proposed for enhancing the recent Coherently-detected Space-Time Shift Keying (CSTSK) scheme employing arbitrary constellations, and it is revealed that the proposed detector is capable of approaching the optimal Maximum Likelihood (ML) detector's performance, while avoiding the exhaustive ML search.
Abstract: A novel reduced-complexity near-optimal detection algorithm is proposed for enhancing the recent Coherently-detected Space-Time Shift Keying (CSTSK) scheme employing arbitrary constellations, such as {\cal L}-point Phase-Shift Keying (PSK) and Quadrature Amplitude Modulation (QAM). The proposed detector relies on a modified Matched Filter (MF) concept. More specifically, we exploit both the constellation diagram of the modulation scheme employed as well as the Inter-Element-Interference (IEI)-free STSK architecture. Furthermore, we generalize the Pulse Amplitude Modulation (PAM)- or PSK-aided Differentially-encoded STSK (DSTSK) concept and conceive its more bandwidth-efficient QAM-aided counterpart. Then, the proposed reduced-complexity CSTSK detector is applied to the QAM-aided DSTSK scheme, which enables us to carry out low-complexity non-coherent detection, while dispensing with channel estimation. It is revealed that the proposed detector is capable of approaching the optimal Maximum Likelihood (ML) detector's performance, while avoiding the exhaustive ML search. Interestingly, our simulation results also demonstrate that the reduced-complexity detector advocated may achieve the same performance as that of the optimal ML detector for the specific STSK scheme's parameters. Another novelty of this paper is that the star-QAM STSK scheme tends to outperform its square-QAM counterpart, especially for high number of dispersion matrices. Furthermore, we provided both the theoretical analysis and the simulations, in order to support this unexpected fact.
TL;DR: A new low-complexity SLM scheme is proposed, which generates alternative signal sequences by adding mapping signal sequences to an OFDM signal sequence, which considerably reduces the computational complexity without sacrificing BER and PAPR reduction performance.
Abstract: The selected mapping (SLM) scheme is one of the well-known peak-to-average power ratio (PAPR) reduction schemes for orthogonal frequency division multiplexing (OFDM) systems. A number of low-complexity SLM schemes have been proposed but most of them reduce the computational complexity at the cost of bit error rate (BER) or PAPR reduction performance degradation. In this paper, a new low-complexity SLM scheme is proposed, which generates alternative signal sequences by adding mapping signal sequences to an OFDM signal sequence. The proposed scheme considerably reduces the computational complexity without sacrificing BER and PAPR reduction performance only by requiring additional memory to save the additive mapping signal sequences, especially for the OFDM system with quadrature amplitude modulation (QAM). Similarly, a low-complexity SLM scheme is proposed for multi-input multi-output (MIMO) OFDM system with space-frequency block code (SFBC).
18 Sep 2011
TL;DR: In this article, a 40-Gb/s W-band 16-QAM radio-over-fiber signal is optically synthesized using dual-polarization QPSK modulator.
Abstract: 40-Gb/s W-band 16-QAM radio-over-fiber signal is optically synthesized using dual-polarization QPSK modulator. Its wireless transmission within FEC limit is demonstrated with optical self-heterodyne detection and digital signal processing.
TL;DR: It was shown that practical communication is only feasible when the line rate of the dimming modulation is at least twice the frequency assigned to the largest multitone subcarrier frequency, and under this constraint and when using a suitably modified demodulation scheme, dimming does not influence the data transmission.
Abstract: In the field of indoor wireless networks, visible-light communications is garnering increasing attention. One of the type of emitters used in this technology is white light-emitting diodes, which can synergistically provide both illumination and data transmission. Discrete multitone modulation is attractive for visible-light communications. One of the issues to be addressed in these synergetic use cases is how to incorporate light dimming while not corrupting the communication link. In this paper, the performance of a visible-light communication system combining pulse-width modulation for dimming and discrete multitone for data transmission was investigated. Performance indicators were addressed, i.e., the signal-to-interference ratio due to dimming and the achievable bit-error ratio in the absence of additional noise. By aid of simulations it was shown that practical communication is only feasible when the line rate of the dimming modulation is at least twice the frequency assigned to the largest multitone subcarrier frequency. The results demonstrate that under this constraint and when using a suitably modified demodulation scheme, dimming does not influence the data transmission.
TL;DR: This in-depth tutorial clarified myths and facts about non-bijective modulation, focusing on superposition modulation (SM).
Abstract: Traditionally, digital modulation schemes are bijective (i.e., the signal constellation points are disjunct), and the mapping is unique. Only recently it has been discovered that non-bijective modulation schemes may outperform bijective modulation schemes when employed in conjunction with suitable channel coding and iterative processing. In this in-depth tutorial, we clarify myths and facts about non-bijective modulation. Emphasis is on superposition modulation (SM). Without active signal shaping, SM outperforms bit-interleaved coded modulation with PSK or square QAM modulation at even lower receiver complexity.
TL;DR: The concept of coordinated multipoint SSK (CoMP-SSK) modulation is put forth as a way of exploiting network cooperation and the spatial-constellation diagram to achieve high data rates.
Abstract: In this paper, we study the performance of space-shift keying (SSK) modulation for multiple-input-multiple-output (MIMO) wireless systems in the presence of multiple-access interference. More specifically, a synchronous multiuser scenario is considered. The main technical contributions of this paper are given as follows: Two receiver structures based on the maximum-likelihood (ML) criterion of optimality are developed and analytically studied, i.e., single- and multiuser detectors. Accurate frameworks for computing the average bit error probability (ABEP) over independent identically distributed (i.i.d.) Rayleigh fading channels are proposed. Furthermore, simple and easy-to-use lower and upper bounds for performance analysis and system design are introduced. The frameworks account for the near-far effect, which significantly affects the achievable performance in multiple-access environments. In addition, we extend the analysis to generalized SSK (GSSK) modulation, which foresees multiple active antennas at the transmitter. With respect to SSK modulation, GSSK modulation achieves higher data rates at the cost of increased complexity at the transmitter. The performance of SSK and GSSK modulations is compared with that of conventional phase-shift keying (PSK) and quadrature amplitude modulation (QAM) schemes, and it is shown that SSK and GSSK modulations can outperform conventional schemes for various system setups and channel conditions. In particular, the performance gain of SSK and GSSK modulations increases for increasing values of the target bit rate and of the number of antennas at the receiver. Finally, we put forth the concept of coordinated multipoint (or network MIMO) SSK (CoMP-SSK) modulation as a way of exploiting network cooperation and the spatial-constellation diagram to achieve high data rates. Analytical derivations and theoretical findings are substantiated through extensive Monte Carlo simulations for many setups.
TL;DR: In this article, a SiGe envelope tracking (ET) cascode power amplifier with an integrated CMOS envelope modulator for mobile WiMAX and 3GPP long-term evolution (LTE) transmitters is presented.
Abstract: This paper presents a SiGe envelope-tracking (ET) cascode power amplifier (PA) with an integrated CMOS envelope modulator for mobile WiMAX and 3GPP long-term evolution (LTE) transmitters (TXs). The entire ET-based RF PA system delivers the linear output power of 22.3/24.3 dBm with the overall power-added efficiency of 33%/42% at 2.4 GHz for the WiMAX 64 quadrature amplitude modulation (64QAM) and the 3GPP LTE 16 quadrature amplitude modulation, respectively. Additionally, it exhibits a highly efficient broadband characteristic for multiband applications. Compared to the conventional fixed-supply cascode PA, our ET-based cascode PA meets the WiMAX/LTE spectral mask and error vector magnitude spec at close to its P1dB compression without the need of predistortion. The SiGe PA and the CMOS envelope modulator are both designed and fabricated in the TSMC 0.35-μm SiGe BiCMOS process on the same die. This study represents an essential integration step toward achieving a fully monolithic large-signal ET-based TX for wideband wireless applications.
TL;DR: It is demonstrated that even under strong nonlinear distortion the transmission reach only reduces by a factor of ~2.5 for a 2 unit increase in capacity when full band DBP is employed, in proportion to the required back-to-back OSNR.
Abstract: We report the performance of coherently-detected nine-channel WDM transmission over high dispersion fibers, using polarization multiplexed m-ary quadrature amplitude modulation (m = 4, 16, 64, 256) at 112 Gbit/s. Compensation of fiber nonlinearities via digital back-propagation enables up to 10 dB improvement in maximum transmittable power and similar to 8 dB Q(eff) improvement which translates to a nine-fold enhancement in transmission reach for PM-256QAM, where the largest improvements are associated with higher-order modulation formats. We further demonstrate that even under strong nonlinear distortion the transmission reach only reduces by a factor of similar to 2.5 for a 2 unit increase in capacity (log(2)m) when full band DBP is employed, in proportion to the required back-to-back OSNR.
TL;DR: An asymptotic bound is presented to quantify the average bit error rate (BER) performance of M-ary quadrature amplitude modulation (M-QAM) SM with optimal-based detection over independent and identically distributed Rayleigh flat fading channels with a novel SM detection scheme, termed multiple-stage (MS) detection.
Abstract: Spatial modulation (SM) is a recent multiple-input multiple-output transmission technique, which entirely avoids inter-channel interference as well as the need for transmit antenna synchronisation. The first objective of this study is to present an asymptotic bound to quantify the average bit error rate (BER) performance of M-ary quadrature amplitude modulation (M-QAM) SM with optimal-based detection over independent and identically distributed Rayleigh flat fading channels. The analytical frameworks are validated by Monte Carlo simulation results, which show that the derived lower bounds are increasingly tight for large signal-to-noise ratio values. The second objective is to introduce a novel SM detection scheme, termed multiple-stage (MS) detection. Performance and complexity comparisons with existing SM detectors show two main benefits of MS detection: near-optimal BER performance and up to a 35% reduction in receiver complexity as compared to the maximum likelihood-based SM detector.
TL;DR: In this paper, the authors describe ultra-high capacity transmission based on spectrally efficient multi-level modulation and wideband optical amplification techniques and demonstrate 69.1 Tb/s transmission over 240 km of low loss pure silica core fibers.
Abstract: This paper describes ultrahigh capacity transmission based on spectrally-efficient multi-level modulation and wideband optical amplification techniques. 21.4-Gbaud polarization-division multiplexed (PDM) 16-ary quadrature amplitude modulation (QAM) signals are generated by utilizing an optical synthesis technique, wavelength-multiplexed with 25-GHz spacing by optical pre-filtering, and received by an intradyne coherent receiver based on digital signal processing (DSP) with pilotless algorithms. These techniques realize a spectral efficiency (SE) of 6.4 b/s/Hz. Furthermore, a hybrid amplification technique that combines distributed Raman and dual-band erbium-doped amplifiers (EDFAs) realizes 10.8-THz signal bandwidth in C- and extended L-bands. By using these techniques, we successfully demonstrate 69.1 Tb/s transmission over 240 km of low loss pure silica core fibers.
TL;DR: Simulation results confirm the effectiveness of the proposed SC-FDMA in terms of EF, power ratio, instantaneous-to-average power ratio and cubic metric performances and Turbo receiver for improved bit error rate (BER) performance.
Abstract: Single-carrier frequency division multiple access (SC-FDMA) has appeared to be a promising technique for high data rate uplink communications. Aimed at SC-FDMA applications, a cyclic prefixed version of the offset quadrature amplitude modulation based OFDM (OQAM-OFDM) is first proposed in this paper. We show that cyclic prefixed OQAM-OFDM (CP-OQAM-OFDM) can be realized within the framework of the standard OFDM system, and perfect recovery condition in the ideal channel is derived. We then apply CP-OQAM-OFDM to SC-FDMA transmission in frequency selective fading channels. Signal model and joint widely linear minimum mean square error (WLMMSE) equalization using a prior information with low complexity are developed. Compared with the existing DFTS-OFDM based SC-FDMA, the proposed SC-FDMA can significantly reduce envelope fluctuation (EF) of the transmitted signal while maintaining the bandwidth efficiency. The inherent structure of CP-OQAM-OFDM enables low-complexity joint equalization in the frequency domain to combat both the multiple access interference and the intersymbol interference. The joint WLMMSE equalization using a prior information guarantees optimal MMSE performance and supports Turbo receiver for improved bit error rate (BER) perform BER) performance. Simulation results confirm the effectiveness of the proposed SC-FDMA in terms of EF (including peak-to-average power ratio, instantaneous-to-average power ratio and cubic metric) and BER performances.
TL;DR: This work proposes a novel cooperative STSK family, which is capable of achieving a flexible rate-diversity tradeoff, in the context of cooperative space-time transmissions, and introduces a beneficial dispersion vector design, which enables it to dispense with symbol-level Inter-Relay Synchronization (IRS).
Abstract: Motivated by the recent concept of Space-Time Shift Keying (STSK), we propose a novel cooperative STSK family, which is capable of achieving a flexible rate-diversity tradeoff, in the context of cooperative space-time transmissions. More specifically, we first propose a Coherent cooperative STSK (CSTSK) scheme, where each Relay Node (RN) activates Decode and-Forward (DF) transmissions, depending on the success or failure of Cyclic Redundancy Checking (CRC). We invoke a bit to-STSK mapping rule, where according to the input bits, one of the Q pre-assigned dispersion vectors is activated to implicitly convey log2 Q bits, which are transmitted in combination with the classic log2 L-bit modulated symbol. Additionally, we introduce a beneficial dispersion vector design, which enables us to dispense with symbol-level Inter-Relay Synchronization (IRS). Further more, the Destination Node (DN) is capable of jointly detecting the signals received from the source-destination and relay destination links, using a low-complexity single-stream-based Maximum Likelihood (ML) detector, which is an explicit benefit of our Inter-Element Interference (IEI)-free system model. More importantly, as a benefit of its design flexibility, our cooperative CSTSK arrangement enables us to adapt the number of the RNs, the transmission rate as well as the achievable diversity order. Moreover, we also propose a Differentially-encoded cooperative STSK (DSTSK) arrangement, which dispenses with CSI estimation at any of the nodes, while retaining the fundamental benefits of the cooperative CSTSK scheme.
01 Jun 2011
06 Mar 2011
TL;DR: In this paper, a serial 10.2-Tb/s transmission system using a 1.28-TBd RZ-16-QAM signal, polarization multiplexing and ultra-fast coherent demultiplexing is presented.
Abstract: We present a serial 10.2-Tb/s transmission-system using a 1.28-TBd RZ-16-QAM signal, polarization multiplexing and ultra-fast coherent demultiplexing. Considering FEC-overhead, we achieve a record error-free net data rate of 9.5-Tb/s and transmission over 29-km.
TL;DR: Simulation and experimental results for a 200 Gb/s DP-16-QAM system demonstrate similar linewidth tolerance to the best feed-forward CPE reported to date while the computational complexity is at least three times lower compared with other simplified feed- forward CPE techniques.
Abstract: A low-complexity feed-forward carrier phase estimation (CPE) technique is presented for dual-polarization (DP)-16-QAM transmission systems. By combining QPSK partitioning, maximum likelihood (ML) detection and phase offset estimation between signals in different polarizations, simulation and experimental results for a 200 Gb/s DP-16-QAM system demonstrate similar linewidth tolerance to the best feed-forward CPE reported to date while the computational complexity is at least three times lower compared with other simplified feed-forward CPE techniques.