Showing papers on "Frequency-division multiplexing published in 2014"
TL;DR: In this paper, a low-complexity model for signal quality prediction in a nonlinear fiber-optic network is developed, which takes into account the signal degradation caused by a combination of chromatic dispersion, nonlinear signal distortion, and amplifier noise.
Abstract: A low-complexity model for signal quality prediction in a nonlinear fiber-optic network is developed. The model, which builds on the Gaussian noise model, takes into account the signal degradation caused by a combination of chromatic dispersion, nonlinear signal distortion, and amplifier noise. The center frequencies, bandwidths, and transmit powers can be chosen independently for each channel, which makes the model suitable for analysis and optimization of resource allocation and routing in large-scale optical networks applying flexible-grid wavelength-division multiplexing.
134 citations
TL;DR: In this paper, a low loss, chip-level frequency multiplexing scheme for readout of scaled-up spin qubit devices is presented. But the authors focus on the few-electron regime.
Abstract: We demonstrate a low loss, chip-level frequency multiplexing scheme for readout of scaled-up spin qubit devices. By integrating separate bias tees and resonator circuits on-chip for each readout channel, we realise dispersive gate-sensing in combination with charge detection based on two radio frequency quantum point contacts. We apply this approach to perform multiplexed readout of a double quantum dot in the few-electron regime and further demonstrate operation of a 10-channel multiplexing device. Limitations for scaling spin qubit readout to large numbers of multiplexed channels are discussed.
108 citations
TL;DR: It is experimentally shown that for bandwidth saving up to 25%, O-SEFDM can achieve the same performance as O-OFDM, and this is the first experimental verification of 25% optical faster than the Nyquist rate.
Abstract: We propose and demonstrate a new optical spectrally efficient frequency division multiplexing (O-SEFDM) system, where non-orthogonal and overlapping sub-carriers are employed to provide higher spectral efficiency relative to optical-orthogonal frequency division multiplexing (O-OFDM). The O-SEFDM technique can increase spectral efficiency in both the electrical and optical domains. It is experimentally shown that for bandwidth saving up to 25%, we can achieve the same performance as O-OFDM. This is the first experimental verification of 25% optical faster than the Nyquist rate. Furthermore, for approximately the same spectral efficiency, 4QAM O-SEFDM outperforms standard 8QAM by 1.6 dB. It is experimentally shown that a lower-order modulation format can achieve a better performance by replacing a higher one.
103 citations
18 Dec 2014
TL;DR: Modelling results show the suitability of the detector for use in large size non-orthogonal multicarrier systems and system modelling results show that this coded system with 1024 sub-carriers can save up to 45% of bandwidth compared to an otherwise equivalent OFDM.
Abstract: Spectrally efficient frequency division multiplexing (SEFDM) improves spectral efficiency relative to the well known orthogonal frequency division multiplexing (OFDM) Optimal detection of SEFDM, to recover signals corrupted by inter carrier interference (ICI), has major drawbacks in the exponential growth of detection complexity with the enlargement of system size and modulation level This poses several challenges to SEFDM practical implementations In this work, we present and compare practicable detection algorithms for both uncoded and coded SEFDM systems In the case of the uncoded system, we discuss a multi-band architecture termed block-spectrally efficient frequency division multiplexing (B-SEFDM) which subdivides the signal spectrum into several blocks, allowing each block to be detected separately The other system discussed in the paper utilizes convolutional coding with an appropriate receiver comprising a fast Fourier transform (FFT) based demodulation and detection working alongside a standard Bahl-Cocke-Jelinek-Raviv (BCJR) decoder Mathematical modelling results show the suitability of the detector for use in large size non-orthogonal multicarrier systems In the presence of multipath frequency selective channel, system modelling results show that this coded system with 1024 sub-carriers can save up to 45% of bandwidth compared to an otherwise equivalent OFDM
52 citations
TL;DR: The proposed converter is capable of handling multiple wavelengths in wavelength division multiplexing (WDM) networks, enabling the conversions between WDM-PDM and W DM-MDM, which is promising to further increase the throughput at the network interface.
Abstract: A compact silicon-on-insulator device used for conversions between polarization division multiplexing (PDM) and mode division multiplexing (MDM) signals is proposed and experimentally demonstrated by utilizing a structure combining the improved two-dimensional grating coupler and two-mode multiplexer. The detailed design of the proposed device is presented and the results show the extinction ratio of 16 and 20 dB for X- and Y-pol input, respectively. The processing of 40 Gb/s signal is achieved within the C-band with good performance. The proposed converter is capable of handling multiple wavelengths in wavelength division multiplexing (WDM) networks, enabling the conversions between WDM-PDM and WDM-MDM, which is promising to further increase the throughput at the network interface.
48 citations
TL;DR: This paper addresses the problem of space-time block code identification for multiple-antenna (MA) orthogonal frequency-division multiplexing (OFDM) systems operating over frequency-selective channels for the first time in literature and develops a binary hypothesis test for decision making.
Abstract: This paper addresses the problem of space-time block code (STBC) identification for multiple-antenna (MA) orthogonal frequency-division multiplexing (OFDM) systems operating over frequency-selective channels for the first time in literature. Previous investigations published on the topic of STBC identification were restricted to single-carrier systems operating over frequency-flat channels. OFDM systems make this topic more challenging to handle since the identifiers work in frequency-selective channels with little or no knowledge of the beginning of the OFDM blocks, OFDM parameters, and frequency-selective channel coefficients. We show that, by taking advantage of the space-time redundancy, STBC identification can be performed by exploiting the cross-correlation of the signals received from different antennas as a discriminating feature. Using this feature, we develop a binary hypothesis test for decision making. The proposed method does not require information about the channel coefficients, modulation format, noise power, or timing of the OFDM and STBC blocks. Moreover, it does not need accurate knowledge of either clock-timing information or OFDM parameters, including the number of sub-carriers and cyclic prefix length. Extensive simulation experiments have verified the effectiveness of the proposed method.
47 citations
TL;DR: In the presence of multipath fading channel, system modelling results show that the new system with 1024 sub-carriers can save up to 40% of bandwidth compared to the OFDM system, and proves that by using the FFT detector, complexity is reduced.
Abstract: Spectrally efficient frequency division multiplexing (SEFDM) improves spectral efficiency, relative to the well known orthogonal frequency division multiplexing (OFDM). A fast Fourier transform (FFT) detector working with a standard Bahl-Cocke-Jelinek-Raviv (BCJR) decoder based on the Turbo principle is proposed to improve iteratively the system performance. In the presence of multipath fading channel, system modelling results show that the new system with 1024 sub-carriers can save up to 40% of bandwidth compared to the OFDM system. In addition, this work proves that by using the FFT detector, complexity is reduced.
47 citations
25 Jun 2014
TL;DR: The analysis reveals that, for delivering fixed and mobile TV services in the same RF channel, the LDM-based system provides much better efficient usage of the spectrum as compared to the single-layer Time-Division-Multiplexing (TDM) or Frequency-Divison-MultipleXing (FDM)-based systems.
Abstract: Cloud transmission (Cloud-Txn) with Layer-Division-Multiplexing (LDM) was proposed as a candidate Physical Layer (PHY) technology for next generation digital TV broadcasting system This paper presents a fundamental analysis on the channel capacity allocation among the different layers of a LDM-based transmission system The analysis reveals that, for delivering fixed and mobile TV services in the same RF channel, by controlling the power allocation among the layers, the LDM-based system provides much better efficient usage of the spectrum as compared to the single-layer Time-Division-Multiplexing (TDM) or Frequency-Division-Multiplexing (FDM)-based systems The spectrum efficiency of LDM allows the simultaneous delivery of a high-data-rate UHDTV service and a mobile HDTV service within a single 6 MHz channel
41 citations
TL;DR: It is demonstrated that the optical Fourier transform and cyclic prefix in an all-optical OFDM transmitter can be simultaneously implemented using a liquid crystal on silicon wavelength selective switch (WSS), which uses phase-modulated optical pulses at the inputs of the WSS.
Abstract: We demonstrate that the optical Fourier transform and cyclic prefix in an all-optical OFDM transmitter can be simultaneously implemented using a liquid crystal on silicon wavelength selective switch (WSS). The design uses phase-modulated optical pulses at the inputs of the WSS; this has the advantage that the optical modulators are only sampled by the optical pulses once per data-symbol, so that the transition times between the data symbols are irrelevant to the performance of the system, allowing slow optical modulators to be used. Furthermore, each input of the WSS can be assigned to any combination of output subcarrier frequencies, including frequencies unrelated to the modal frequencies of the comb source. This is especially useful for testing in-service ultra-high bandwidth systems by applying additional wavelengths. As an example, we generate a 10.08 Tb/s signal and transmit along 857.4 km of fiber using 252 10-Gbaud subcarriers with a 10% cyclic prefix. We use an optically-banded digital subcarrier demultiplexer to simultaneously detect three subcarriers using a single coherent receiver.
39 citations
TL;DR: The optimality of the two-step over the direct approach in systematic UW-OFDM is proved analytically, a heuristic algorithm is presented that allows a fast numerical optimization of the redundant subcarrier positions, and it is shown that the original intuitive approach of spreading the redundancy subcarriers in systematically encoded UW- OFDM by minimizing the mean redundant energy is practically also optimum w.r.t. transceiver based cost functions.
Abstract: Unique word-orthogonal frequency division multiplexing (UW-OFDM) is a novel signaling concept where the guard interval is implemented as a deterministic sequence, the so-called unique word. The UW is generated by introducing a certain level of redundancy in the frequency domain. Different data estimation strategies and the favourable bit error ratio (BER) performance of UW-OFDM, as well as comparisons to competing concepts have already extensively been discussed in previous papers. This work focuses on the different possibilities on how to generate UW-OFDM signals. The optimality of the two-step over the direct approach in systematic UW-OFDM is proved analytically, we present a heuristic algorithm that allows a fast numerical optimization of the redundant subcarrier positions, and we show that our original intuitive approach of spreading the redundant subcarriers in systematically encoded UW-OFDM by minimizing the mean redundant energy is practically also optimum w.r.t. transceiver based cost functions. Finally, we derive closed form approximations of the statistical symbol distributions on individual subcarriers as well as the redundant energy distribution and compare them with numerically found results.
39 citations
TL;DR: Numerical results show that the clustered-OFDM schemes based on HS-OF DM provide the same bit-error-rate performance and can trade off channel capacity for CC, which can give rise to low-priced transceivers for PLC technologies.
Abstract: This study presents a comprehensive analysis to highlight advantages and disadvantages, in terms of channel capacity and computational complexity (CC), of a so-called clustered-orthogonal frequency division multiplexing (OFDM) scheme for power line communication (PLC) technologies for access networks. By taking into account filtering, decimation and upsampling techniques, the implementations of two transmitter schemes, named 𝒫(·)-I and 𝒫(·)-II, and three receivers ones, named 𝒬(·)-I, 𝒬(·)-II and 𝒬(·)-III, that can be easily derived from the hermitian symmetric OFDM (HS-OFDM) scheme are discussed. Numerical results show that the clustered-OFDM schemes based on HS-OFDM provide the same bit-error-rate performance as that of HS-OFDM, double sideband-OFDM and single sideband-OFDM. Also, clustered-OFDM based on the combination of 𝒬(·)-II and 𝒬(·)-III offers the lowest CC for both baseband and passband data communications. Further, it is demonstrated that the clustered-OFDM schemes can trade off channel capacity for CC, which can give rise to low-priced transceivers for PLC technologies. Finally, a comparative analysis of clustered-OFDM and orthogonal frequency division multiple access (OFDMA) points out the scenarios in which clustered-OFDM can be competitive if the complexity of the OFDM transceiver is a primary consideration.
09 Mar 2014
TL;DR: This work experimentally generates subcarrier multiplexed signals using high-speed DACs and demonstrates the improved nonlinearity tolerance over single carrier signals in long-haul coherent optical transmission systems.
Abstract: We experimentally generate subcarrier multiplexed signals using high-speed DACs and demonstrate the improved nonlinearity tolerance over single carrier signals in long-haul coherent optical transmission systems.
TL;DR: It is theoretically and experimentally shown that simple channel estimation can be realized in offset-QAM OFDM with the achieved performance close to the theoretical limit and this technology very promising for optical communication systems.
Abstract: Offset quadrature amplitude modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) exhibits enhanced net data rates compared to conventional OFDM, and reduced complexity compared to Nyquist FDM (N-FDM). However, channel estimation in discrete-Fourier-transform (DFT) based offset-QAM OFDM is different from that in conventional OFDM and requires particular study. In this paper, we derive a closed-form expression for the demultiplexed signal in DFT-based offset-QAM systems and show that although the residual crosstalk is orthogonal to the decoded signal, its existence degrades the channel estimation performance when the conventional least-square method is applied. We propose and investigate four channel estimation algorithms for offset-QAM OFDM that vary in terms of performance, complexity, and tolerance to system parameters. It is theoretically and experimentally shown that simple channel estimation can be realized in offset-QAM OFDM with the achieved performance close to the theoretical limit. This, together with the existing advantages over conventional OFDM and N-FDM, makes this technology very promising for optical communication systems.
TL;DR: It is shown that offset-QAM OFDM exhibits negligible penalty for all investigated spectra, in contrast to rectangular- function based Nyquist FDM (N-FDM) and sinc-function based conventional OFDM (C-OFDM), and by avoiding the GI, 112-Gb/s polarization multiplexed offset-4QAM OfDM can achieve 23% increase in net data rate over C-OF DM under the same transmission reach.
Abstract: We experimentally demonstrate and numerically investigate a discrete-Fourier-transform (DFT) based offset quadrature-amplitude-modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) system. We investigate the scheme using a set of square-root-raised-cosine functions and a set of super-Gaussian functions as signal spectra. It is shown that offset-QAM OFDM exhibits negligible penalty for all investigated spectra, in contrast to rectangular-function based Nyquist FDM (N-FDM) and sinc-function based conventional OFDM (C-OFDM). The required guard interval (GI) length for dispersion compensation in offset-QAM OFDM is analyzed and shown to scale with twice the subcarrier spacing rather than the full OFDM bandwidth. Experimental results show that 38-Gb/s offset-16QAM OFDM supports 600-km fiber transmission with negligible penalty in the absence of GI while a GI length of eight is required in C-OFDM. Further numerical simulations show that by avoiding the GI, 112-Gb/s polarization multiplexed offset-4QAM OFDM can achieve 23% increase in net data rate over C-OFDM under the same transmission reach. We also discuss the design of the pulse-shaping filter in the DFT-based implementation and show that when compared to N-FDM, the required memory length of the filter for pulse shaping can be reduced from 60 to 2 in offset-QAM OFDM regardless of the fiber length.
TL;DR: The results show that MRRs support both single-carrier and multi- carrier optical soliton pulses, which can be used in an OFDM based on whether fast Fourier transform or discrete wavelet transform transmission/receiver system.
Abstract: Microring resonators (MRRs) can be used to generate optical millimetre-wave solitons with a broadband frequency of 40-60 GHz. Non-linear light behaviours within MRRs, such as chaotic signals, can be used to generate logic codes (digital codes). The soliton signals can be multiplexed and modulated with the logic codes using an orthogonal frequency division multiplexing (OFDM) technique to transmit the data via a network system. OFDM uses overlapping subcarriers without causing inter-carrier interference. It provides both a high data rate and symbol duration using frequency division multiplexing over multiple subcarriers within one channel. The results show that MRRs support both single-carrier and multi-carrier optical soliton pulses, which can be used in an OFDM based on whether fast Fourier transform or discrete wavelet transform transmission/receiver system. Localised ultra-short soliton pulses within frequencies of 50 and 52 GHz can be seen at the throughput port of the panda system with respect to full-width at half-maximum (FWHM) and free spectrum range of 5 MHz and 2 GHz, respectively. The soliton pulses with FWHMs of 10 MHz could be generated at the drop port. Therefore, transmission of data information can be performed via a communication network using soliton pulse carriers and an OFDM technique.
TL;DR: An iterative receiver to enhance the performance of hybrid asymmetrically clipped optical orthogonal frequency division multiplexing (HACO-OFDM) in optical wireless communication systems and pairwise clipping is utilized to further reduce the effect of noise and estimation error, resulting in improved performance.
Abstract: This paper proposes an iterative receiver to enhance the performance of hybrid asymmetrically clipped optical orthogonal frequency division multiplexing (HACO-OFDM) in optical wireless communication systems. In HACO-OFDM scheme, asymmetrically clipped optical OFDM (ACO-OFDM) and pulse-amplitude-modulated discrete multitone (PAM-DMT) signals are transmitted simultaneously, which is more spectrally efficient compared with ACO-OFDM and PAM-DMT. However, the existing HACO-OFDM receiver directly recovers the signals in the frequency domain, which could not eliminate the interference thoroughly between ACO-OFDM and PAM-DMT signals and limits its performance. In our proposed receiver, the ACO-OFDM and PAM-DMT signals are detected in the frequency domain and regenerated in the time domain. After that, they are subtracted from the received signals iteratively. Thus, ACO-OFDM and PAM-DMT signals can be distinguished. By taking advantage of the signal symmetry properties of ACO-OFDM and PAM-DMT in the time domain, pairwise clipping is utilized to further reduce the effect of noise and estimation error, resulting in improved performance. In addition, unequal power allocation is proposed to guarantee that ACO-OFDM and PAM-DMT signals have similar performance in HACO-OFDM systems. Simulation results show that the proposed method provides significant signal-to-noise ratio gain over the conventional receiver for both equal and unequal power allocations at the cost of slightly increased complexity.
01 Dec 2014
TL;DR: An analytical model is proposed to evaluate UNB performance in terms of packet loss ratio and normalized throughput in both terrestrial and satellite context and several axes of improvement based on advanced signal processing techniques are proposed to enhance the capacity of a system using UNB signals.
Abstract: Ultra Narrow Band (UNB) transmission technique makes a powerful comeback in the frame of Machine-To-Machine (M2M) communications thanks to advances in signal processing. After explaining why, among others, it is one of the best candidate for Low Power Wide Area (LPWA) communications, we present its specificities and associated constraints. In particular UNB is inseparable from random access so we introduce Time/Frequency Aloha, a random access scheme adapted for UNB. Then, we propose an analytical model to evaluate its performance in terms of packet loss ratio and normalized throughput in both terrestrial and satellite context. Several axes of improvement based on advanced signal processing techniques are proposed to enhance the capacity of a system using UNB signals.
23 Oct 2014
TL;DR: GFDM, a candidate waveform for the 5G PHY layer, is shown to be able to use the LTE master clock and the same time-frequency structure as employed in today's generation of cellular systems.
Abstract: The soft transition between generations of mobile communication systems is a desirable feature for telecommunication operators and device manufacturers. Looking to the past, clock compatibility between WCDMA and LTE allowed manufacturers to build inexpensive multi-standard devices. In this paper it is shown that GFDM, a candidate waveform for the 5G PHY layer, is able to use the LTE master clock and the same time-frequency structure as employed in today's generation of cellular systems. Two approaches for coexistence of 4G/5G waveforms are presented in the paper. The first GFDM setting is aligned with the LTE grid; in the other one GFDM acts as a secondary system to the primary LTE. The second approach introduces a new way of positioning subcarriers that further enhances the flexibility of GFDM. In addition, the paper also considers low latency aspects for autonomous and human controlled device communication in future application scenarios.
TL;DR: This letter proposes an efficient nonlinear digital cancellation technique to suppress the transmitter OOB emissions in the receiver path, enabling sufficient TX-RX isolation in frequency division duplexing (FDD) transceivers without any extra analog/RF filtering or PA linearization.
Abstract: As the duplexing distances in emerging wireless systems are getting more and more narrow, achieving sufficient isolation between transmit and receive chains using radio frequency (RF) filtering alone becomes increasingly complex Particularly challenging problem in this context is the spectral regrowth of nonlinear power amplifiers (PAs) in the transmit chain, and other transmitter out-of-band (OOB) emissions, which can heavily desensitize the receiver chain In this letter, we first carry out detailed modeling of transmitter OOB emissions due to practical wideband PAs with memory effects Stemming from this modeling, and using the known digital transmit data inside the transceiver as reference, we then propose an efficient nonlinear digital cancellation technique to suppress the transmitter OOB emissions in the receiver path The proposed technique is verified and analyzed using extensive computer simulations, rendering excellent suppression properties, hence enabling sufficient TX-RX isolation in frequency division duplexing (FDD) transceivers without any extra analog/RF filtering or PA linearization
TL;DR: In this article, the application of optical polarization-multiplexed radio-over-fiber wireless backhauling of fully standard 3GPP carrier-aggregated multiple-input multiple-output (MIMO) signals is demonstrated experimentally.
Abstract: This paper proposes and demonstrates experimentally the application of optical polarization-multiplexed radio-over-fiber wireless backhauling of fully standard 3GPP carrier-aggregated multiple-input multiple-output (MIMO) signals. The experimental work demonstrates successful long-reach optical transmission of 3GPP carrier-aggregated LTE-Advanced (LTE-A) signals using 2×2 MIMO spatial diversity. The suitability of MIMO provision using radio-over-fiber optical links is demonstrated over different E-UTRA frequency division duplex frequency bands. The performance of electrical carrier aggregation is evaluated in different configurations comprising one, three and five LTE-A component carriers of 10 and 20 MHz bandwidth each. The experimental results demonstrate successful 2×2 MIMO radio-over-fiber polarization-multiplexed transmission of five LTE-A carriers over 25 km, three LTE-A carriers over 75 km and an LTE-A carrier over 100 km of standard single mode fiber to provide pervasive MIMO wireless service to a large number of users.
06 Mar 2014
TL;DR: In this paper, a wavelet-based OFDM is proposed at the place of Discrete Fourier Transform (DFT) based OFDM in 4th Generation Long Term Evolution (LTE).
Abstract: Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input and Multiple Output (MIMO) are two main techniques employed in 4th Generation Long Term Evolution (LTE). In OFDM multiple carriers are used and it provides higher level of spectral efficiency as compared to Frequency Division Multiplexing (FDM). In OFDM because of loss of orthogonality between the subcarriers there is intercarrier interference (ICI) and intersymbol interference (ISI) and to overcome this problem use of cyclic prefixing (CP) is required, which uses 20% of available bandwidth. Wavelet based OFDM provides good orthogonality and with its use Bit Error Rate (BER) is improved. Wavelet based system does not require cyclic prefix, so spectrum efficiency is increased. It is proposed to use wavelet based OFDM at the place of Discrete Fourier Transform (DFT) based OFDM in LTE. We have compared the BER performance of wavelets and DFT based OFDM.
Journal Article•
TL;DR: Free space optical communication paves the way for a high bandwidth requiring applications with license free operation, high transmission security, full duplex transmission and protocol transparency will give a broader view to free space optical Communication.
Abstract: In the recent past, free-space optical communication (FSO) proved to be an important replacement to radio frequency communication. In optical fiber cable communication, there is a disadvantage that optical fiber gets damaged in a long distance installation. Radio frequency communication also deals with limitations of bandwidth and data rate. In this paper, a brief description about free space optical (FSO) communication and its connectivity with central cellular network is explained. This paper also provides the information about the role of free space optics in the central cellular network. It contains an RF network, which has connections within the Radio Access Network (RAN) and the Central Network (CN) for connecting the mobile user subscriber to the Public Switched Telephone Networks (PSTN) and Internet. Moreover, free space optical communication paves the way for a high bandwidth requiring applications with license free operation, high transmission security, full duplex transmission and protocol transparency will give a broader view to free space optical communication.
TL;DR: In this article, the authors demonstrate the seamless integration of full duplex system frequency division duplex (FDD) long-term evolution (LTE) technology with radio over fiber (RoF) for eNodeB (eNB) coverage extension.
Abstract: In this paper, we experimentally demonstrate the seamless integration of full duplex system frequency division duplex (FDD) long-term evolution (LTE) technology with radio over fiber (RoF) for eNodeB (eNB) coverage extension. LTE is composed of quadrature phase-shift keying (QPSK), 16-quadrature amplitude modulation (16-QAM) and 64-QAM, modulated onto orthogonal frequency division multiplexing (OFDM) and single-carrier-frequency division multiplexing for downlink (DL) and uplink (UL) transmissions, respectively. The RoF system is composed of dedicated directly modulated lasers for DL and UL with dense wavelength division multiplexing (DWDM) for instantaneous connections and for Rayleigh backscattering and nonlinear interference mitigation. DL and UL signals have varying carrier frequencies and are categorized as broad frequency spacing (BFS), intermediate frequency spacing (IFS), and narrow frequency spacing (NFS). The adjacent channel leakage ratio (ACLR) for DL and UL with 64-QAM are similar for all frequency spacings while cross talk is observed for NFS. For the best case scenario for DL and UL transmissions we achieve error vector magnitude (EVM) values of ~2.30%, ~2.33%, and ~2.39% for QPSK, 16-QAM, and 64-QAM, respectively, while for the worst case scenario with a NFS EVM is increased by 0.40% for all schemes.
02 Jun 2014
TL;DR: A novel high sampling rate multi-pulse phase-sensitive OTDR (Φ-OTDR) employing frequency division multiplexing (FDM) is proposed to increase the sampling rate of the long distance sensor system and is experimentally verified.
Abstract: A novel high sampling rate multi-pulse phase-sensitive OTDR (Φ-OTDR) employing frequency division multiplexing (FDM) is proposed to increase the sampling rate of the long distance sensor system. Compared with the conventional Φ- OTDR, the new system owns much higher detection bandwidth as more probe pulses are allowed simultaneously traveling in the sensing fiber. The feasibility of the technique is experimentally verified. By multiplexing four different frequencies, we realize a experimental system with 20kHz vibration detection bandwidth over 10km sensing range.
Proceedings Article•
14 May 2014TL;DR: In this article, a waveform design approach based on bi-orthogonal frequency division multiplexing (FDMM) was proposed to handle the highly asynchronous access of different devices and to allow transmission of control signaling and payload in one shot.
Abstract: One of the main drivers for new waveforms in future 5G wireless communication systems is to handle efficiently the variety of traffic types and requirements In this paper, we introduce a new random access within the standard acquisition procedures to support sporadic traffic as an enabler of the Internet of Things (IoT) The major challenge hereby is to cope with the highly asynchronous access of different devices and to allow transmission of control signaling and payload "in one shot" We address this challenge by using a waveform design approach based on bi-orthogonal frequency division multiplexing We show that this approach allows data transmission in frequencies that otherwise have to remain unused More precisely, we utilize frequencies previously used as guard bands, located towards the standard synchronous communication pipes as well as in between the typically small amount of resources used by each IoT device We demonstrate the superiority of this waveform approach over the conventional random access using numerical experiments
23 Jul 2014
TL;DR: A Block Efficient Detector (BED) is presented in this work and computer simulations show that the performance is improved by at most 4.5 dB while the complexity is decreased by one order of magnitude.
Abstract: Spectrally Efficient Frequency Division Multiplexing (SEFDM) is a non-orthogonal multicarrier communication technique that can pack more sub-carriers than Orthogonal Frequency Division Multiplexing (OFDM) in a given bandwidth In this work, we propose a multi-band architecture named Block-Spectrally Efficient Frequency Division Multiplexing (B-SEFDM) for a large non-orthogonal system Furthermore, a Block Efficient Detector (BED) is presented in this work and computer simulations show that the performance is improved by at most 45 dB while the complexity is decreased by one order of magnitude Finally, a butterfly structure, which is reconfigurable according to required complexity/throughput, is proposed here for the detection
TL;DR: In this article, the authors presented the new trends of the performance evaluation of submarine fiber cable system with different ultra-high multiplexing and propagation techniques over a wide range of the affecting parameters.
Abstract: This paper has presented the new trends of the performance evaluation of submarine fiber cable system with different ultra-high multiplexing and propagation techniques over a wide range of the affecting parameters. We have taken into account the ultimate optical transmission of 10,000 channels huge submarine cables under different depth conditions. Two amplification techniques are considered (the engagement of Raman and Erbium-doped fiber amplifiers). The double impact of both temperature and pressure is investigated through the defined depth penalty. Three transmission time division multiplexing techniques are studied, namely soliton, nonlinear and maximum time division multiplexing. Also, two multiplexing methods are considered in the design of ultra-wide wavelength division multiplexing (UW-WDM) (10,000 optical channels) and ultra-wide space division multiplexing UW-SDM (400 fiber links). Based on experimental data, both the deep ocean water temperature and pressure are tailored as functions of the water depth. The product of the transmitted bit rate and the repeater spacing is processed over wide ranges of the affecting parameters, where both the repeater spacing and the transmitted soliton bit rate are in positive correlations with the total number of links.
TL;DR: In this paper, the authors proposed a next-generation long-reach access optical network (35 dB loss budget + 2 dB margin) delivering up to 40G/40G per passive 1:256 optical distribution network.
Abstract: We introduce a next-generation long-reach access optical network (35 dB loss budget +2 dB margin) delivering up to 40G/40G per passive 1:256 optical distribution network, supporting symmetrical 1 Gb/s rates per home user or up to 40 Gb/s for business users (e.g., enterprises, antenna sites). The proposed system is based on a novel spectrally efficient orthogonal frequency division multiplexing/wavelength division multiplexing OFDM/WDM architecture symmetrically using 16-QAM OFDM polarization diversity in both the downstream and upstream in order to serve low-cost energy-efficient symmetric 1 Gb/s optical network units (ONUs), which are self-coherent, laserless, colorless, and tunable-filter-free. Each ONU comprises a standard semiconductor optical amplifier (SOA), a silicon-based photonic integrated circuit (PIC), and mixed-signal electronic integrated circuits (ICs) performing the signal processing at a relatively slow rate as compared with the overall passive optical network (PON) throughput: digital to analog converters (DACs) and analog to digital converters (ADCs) at 417 MS/s for the home user ONUs.
TL;DR: Simulation results prove that the CMLP aided MUD performs better than the MMSE and MSER techniques in terms of enhanced bit error rate performance with low computational complexity.
Abstract: The space division multiple access–orthogonal frequency division multiplexing (SDMA–OFDM) wireless system has become very popular owing high spectral efficiency and high load capability. The optimal maximum likelihood multiuser detection (MUD) technique suffers from high computational complexity. On the other hand the linear minimum mean square error (MMSE) MUD techniques yields poor performance and also fails to detect users in overload scenario, where the number of users are more than that of number of receiving antennas. By contrast, the differential evolution algorithm (DEA) aided minimum symbol error rate (MSER) MUD can sustain in overload scenario as it can directly minimizes probability of error rather than mean square error. However, all these classical techniques are still complex as these do channel estimation and multiuser detection sequentially. In this paper, complex multi layer perceptron (CMLP) neural network model is suggested for MUD in SDMA–OFDM system as it do both channel approximation and MUD simultaneously. Simulation results prove that the CMLP aided MUD performs better than the MMSE and MSER techniques in terms of enhanced bit error rate performance with low computational complexity.
27 Aug 2014
TL;DR: Three new algorithms for generation and reception of SEFDM-signals based on FFT/IFFT are proposed and it is shown that the proposed schemes outperform the proposed earlier by 1,2-6 times.
Abstract: A study of Spectrally Efficient Frequency Division Multiplexing (SEFDM) signals generation is done. Three new algorithms for generation and reception of SEFDM-signals based on FFT/IFFT are proposed. Their complexity and conditions of applicability are analyzed. It is shown that the proposed schemes outperform the proposed earlier by 1,2-6 times. The BER performance of the developed methods for AWGN channel is analyzed, it is shown that the number of the guard subcarriers significantly affects the BER performance of SEFDM (up to 4 dB energy loss when doubling the guard part of the signal).