Showing papers on "Phase-shift keying published in 2013"
TL;DR: This paper addresses the problem of amplify-and-forward (AF) relaying in a hybrid satellite-terrestrial link, where a masked destination node receives the relayed transmission from a terrestrial link and direct transmission from the satellite link.
Abstract: In this paper, the transmission of signals in a hybrid satellite-terrestrial link is considered. In particular, we address the problem of amplify-and-forward (AF) relaying in a hybrid satellite-terrestrial link, where a masked destination node receives the relayed transmission from a terrestrial link and direct transmission from the satellite link. The satellite-relay and satellite-destination links are assumed to follow the Shadowed-Rician fading; and the channel of the terrestrial link between the relay and destination is assumed to follow the Nakagami-m fading. The average symbol error rate of the considered AF cooperative scheme for M-ary phase shift keying constellation is derived for these generalized fading channels. Moreover, analytical diversity order of the hybrid system is also obtained.
192 citations
TL;DR: Simulation results show that after three iterations, the original OICF algorithm can achieve the desired PAPR while the simplified one exhibits almost the same performance.
Abstract: Iterative clipping and filtering (ICF) is a well-known technique to reduce the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals. Recently, Wang and Luo investigated the clipped signal and proposed a modified algorithm called optimized ICF (OICF). This is an optimal algorithm since it can achieve the required PAPR reduction with minimum in-band distortion and far fewer iterations. However, OICF needs to solve a convex optimization problem with O(N3) complexity, where N represents the number of subcarriers. In this paper, instead of analyzing the clipped signal, we study the clipping noise and propose a simplified OICF algorithm. In the new algorithm, solving the convex optimization problem is approximated by some simple algebraic operations and the computational complexity reduces to O(N). Simulation results show that after three iterations, the original OICF algorithm can achieve the desired PAPR while the simplified one exhibits almost the same performance: for a 128-subcarrier and quadrature phase shift keying (QPSK) modulated OFDM system, the PAPR-reduction performance difference between the two algorithms are 5×10-3dB at a 10-4 clipping probability and the bit-error-rate performance difference is 6×10-3 dB at a 10-7 error probability.
149 citations
TL;DR: To the authors' knowledge, this is the first demonstration of a 400G optical wireless integration system in mm-wave frequency bands and also a capacity record of wireless delivery.
Abstract: We experimentally demonstrate a record 400G optical wireless integration system simultaneously delivering 2 × 112 Gb/s two-channel polarization-division-multiplexing 16-ary quadrature amplitude modulation (PDM-16QAM) signal at 37.5 GHz wireless carrier and 2 × 108 Gb/s two-channel PDM quadrature phase shift keying (PDM-QPSK) signal at 100 GHz wireless carrier, adopting two millimeter-wave (mm-wave) frequency bands, two orthogonal antenna polarizations, multiple-input multiple-output (MIMO), photonic mm-wave generation and advanced digital signal processing (DSP). In the case of no fiber transmission, the bit error ratios (BERs) for both the 112 Gb/s PDM-16QAM signal after 1.5 m wireless delivery at 37.5 GHz and the 108 Gb/s PDM-QPSK signal after 0.7 m wireless delivery at 100 GHz are below the pre-forward-error-correction (pre-FEC) threshold of 3.8 × 10−3. To our knowledge, this is the first demonstration of a 400G optical wireless integration system in mm-wave frequency bands and also a capacity record of wireless delivery.
142 citations
TL;DR: In this article, the authors demonstrated a seamless integrated fiber-wireless system that delivers multichannel 120-Gb/s data through 80-km fiber and 2-m 2×2 multiple-input multiple-output (MIMO) wireless link at 92-GHz W-band adopting polarization division multiplexing quadrature phase shift keying (PDM-QPSK) modulation.
Abstract: We experimentally demonstrated a seamlessly integrated fiber-wireless system that delivers multichannel 120-Gb/s data through 80-km fiber and 2-m 2×2 multiple-input multiple-output (MIMO) wireless link at 92-GHz W-band adopting polarization division multiplexing quadrature phase shift keying (PDM-QPSK) modulation. The three-channel 3×40-Gb/s optical PDM-QPSK signals with 12.5-GHz channel spacing are simultaneously upconverted to 92-GHz wireless carrier by optical polarization-diversity heterodyne beating and then transmitted and received by two pairs of transmitter and receiver antennas, which form a full 2×2 MIMO wireless link. At the wireless receiver, a two-stage analog and digital downconversion is performed. Polarization and wireless 2×2 MIMO demultiplexing are realized by constant modulus algorithm based on digital signal processing. The bit-error ratio performance for the 120-Gb/s PDM-QPSK signal is measured after 80-km single-mode fiber-28 and 2-m wireless transmission.
107 citations
TL;DR: It is found that coherent OWC systems typically outperform subcarrier intensity modulation systems, with 24-30 dB improvements in sensitivity, mainly due to their elimination of thermal and background noise effects.
Abstract: A detailed analysis and comparison is carried out for optical wireless communications (OWCs) with coherent and subcarrier-intensity-modulation-based systems, which are the two major implementations for detection-threshold-free operation without irreducible error floors. Error rate performance is studied for communications with binary phase-shift keying, differential phase-shift keying, and noncoherent frequency-shift keying over weak-to-strong (gamma-gamma distributed) turbulence conditions. Series-form error rate expressions are also derived for diversity reception schemes, including maximum ratio combining, equal gain combining, and selection combining. Based on our analysis, it is found that coherent OWC systems typically outperform subcarrier intensity modulation systems, with 24-30 dB improvements in sensitivity, mainly due to their elimination of thermal and background noise effects. The performance improvements of coherent systems are confirmed through numerical studies. The findings can offer significant benefits for future OWC systems that are subject to transmitted power limitations.
102 citations
TL;DR: The implemented system exploits polarization (PM) and wavelength multiplexing, achieving the transmission of a total capacity of 1.6 Tbit/s over hybrid fiber free-space optics system with no optical-electronic-optical conversion at the interfaces with air.
Abstract: We present a high-data rate optical wireless system. The implemented system exploits polarization (PM) and wavelength multiplexing, achieving the transmission of a total capacity of 1.6 Tbit/s over hybrid fiber free-space optics (FSO) system with no optical-electronic-optical conversion at the interfaces with air. Quadrature phase shift keying modulation in each channel and coherent detection were used. The system allows enough power budget to support the record transmission of 16 channels, operating each at 100 Gbit/s over 40 km of fiber and 80 m of FSO between two buildings. Performance of the fully transparent connection is presented in terms of bit-error rate.
87 citations
TL;DR: A novel solution for hard-decision-aided SM/STSK detection, which retains its optimal performance, despite its reduced detection complexity, when either LPSK or LQAM is employed.
Abstract: In this paper, we propose a comprehensive reduced-complexity detector both for hard-decision-aided as well as for the soft-decision-assisted Spatial Modulation (SM)/Space-Time Shift Keying (STSK). More explicitly, the detection of the SM scheme, which activates a single one out of M antennas to transmit a single LPSK/QAM symbol, may be carried out by detecting the antenna activation index m and the LPSK/QAM symbol st separately, so that the detection complexity may be reduced from the order of O(M · L) to the lower bound of O(M + log2 L). However, the QAM aided STSK hard detection proposed in [1] results in a performance loss. Furthermore, the Max-Log-MAP algorithm proposed for soft STSK detection in [2] only takes into account the maximum a posteriori probabilities, which also imposed a performance degradation. Therefore, in this paper, we propose a novel solution for hard-decision-aided SM/STSK detection, which retains its optimal performance, despite its reduced detection complexity, when either LPSK or LQAM is employed. Furthermore, we propose the reduced-complexity Approx-Log-MAP algorithm conceived for the soft-decision-aided SM/STSK detector, in order to replace the suboptimal Max-Log-MAP algorithm.
74 citations
TL;DR: In this article, a blind adaptive equalizer is proposed to track and compensate the skew while also performing matched filtering, and performance is investigated in simulation for 56 GBd polarization division multiplexed 16-quadrature amplitude modulation (PDM-16QAM).
Abstract: In-phase and quadrature skew inside a coherent receiver, caused by misalignments, can severely limit performance. Future 400G systems employing higher order modulation formats and Nyquist filtering are especially sensitive to this. A blind adaptive equalizer is proposed to track and compensate the skew while also performing matched filtering. Performance is investigated in simulation for 56 GBd polarization division multiplexed 16-quadrature amplitude modulation (PDM-16QAM) and experimentally for 6 GBd PDM quadrature phase shift keying (PDM-QPSK) and PDM-16QAM, where compensation for delays up to half a symbol period are demonstrated without penalty. At 30% delay skew, the maximum skew recommended by Optical Internetwork Forum (OIF) for PDM-QPSK, a gain of 1.6 dB for PDM-QPSK, and a gain of more than 5 dB for PDM-16QAM is observed compared with using a conventional equalizer.
74 citations
TL;DR: It is demonstrated how an initial information pattern can be recovered (without direct backward propagation) through the calculation of nonlinear spectral data of the received optical signal.
Abstract: Through numerical modeling, we illustrate the possibility of a new approach to digital signal processing in coherent optical communications based on the application of the so-called inverse scattering transform. Considering without loss of generality a fiber link with normal dispersion and quadrature phase shift keying signal modulation, we demonstrate how an initial information pattern can be recovered (without direct backward propagation) through the calculation of nonlinear spectral data of the received optical signal.
72 citations
TL;DR: A high-efficiency, large output-power, mm-wave digital transmitter architecture is proposed for high data rate m-ary QAM transmission and its suitability as a large-swing NRZ modulator driver in fiberoptic links is demonstrated.
Abstract: A high-efficiency, large output-power, mm-wave digital transmitter architecture is proposed for high data rate m-ary QAM transmission. Because it operates entirely in digital mode, without any matching networks, it is scalable in frequency up to at least 50 GHz and portable to future generations of CMOS technologies. It consists of n broadband mm-wave IQ power-DAC pairs directly modulated in amplitude and phase by 4 x n independent digital data streams. The output signals combine in free space to form a programmable ASK, BPSK, QPSK, and m-ary QAM mm-wave transmitter. Several proof-of-concept circuits with one DAC cell, and with one and two IQ pairs of DAC cells were fabricated in 45-nm SOI CMOS. Using a series-stacked differential output stage with four cascoded n-MOSFETs driven in saturation by a CMOS-inverter chain, each power-DAC cell demonstrates a 24.3 dBm output power with 21.3% drain efficiency and 14.6% PAE, at 45 GHz directly into 50-Ω loads. The peak drain efficiency is 30% at 22.5 dBm output power and 19.4% PAE. Experiments show 5-Gb/s BPSK, and simultaneous 2-Gb/s BPSK and 2-Gb/s ASK modulation per DAC cell in the 44–48 GHz range. Eye diagrams at 28 Gb/s further demonstrate the broadband operation of the DAC cell and its suitability as a large-swing NRZ modulator driver in fiberoptic links.
71 citations
TL;DR: It is seen that, although the impact of turbulence is severe, a proper selection of APD average gain could significantly improve the system performance in both cases of turbulence channels.
Abstract: In this study, the authors theoretically study the performance of direct-detection free-space optical communication systems using binary phase-shift keying subcarrier-intensity modulation and avalanche photodiode (APD). The system bit-error rate and channel capacity are theoretically derived in cases of log-normal and gamma-gamma channel models for weak-to-moderate and moderate-to-strong atmospheric turbulence conditions, respectively. The authors quantitatively discuss the optimal values of the APD average gain, required transmitted optical power, and operating bit-rate considering various turbulence conditions, APD shot noise and thermal noise. It is seen that, although the impact of turbulence is severe, a proper selection of APD average gain could significantly improve the system performance in both cases of turbulence channels. The optimal value of APD average gain remains almost the same for different levels of turbulence; nevertheless it varies significantly in accordance to the change of receiver noise temperature.
TL;DR: In this paper, the authors investigated spatial diversity techniques for subcarrier phase-shift keying (PSK)-modulated optical communication links over the Gamma-Gamma channels, and showed that the diversity order of the studied system depends only on the effective number of small-scale cells of the scattering process in the atmosphere.
Abstract: We investigate spatial diversity techniques for subcarrier phase-shift keying (PSK)-modulated optical wireless communication links over the Gamma-Gamma channels. Both repetition code and the Alamouti-type orthogonal space-time block code (OSTBC) are considered. Highly accurate series error rate expressions are derived by using a moment generating function approach with a series expansion of the modified Bessel function. Truncation error analyses and asymptotic error rate analyses are also presented. Our asymptotic analyses show that the diversity order of the studied system depends only on the effective number of small-scale cells of the scattering process in the atmosphere. Our performance analyses confirm that the repetition code outperforms OSTBC for subcarrier PSK-based systems over the Gamma-Gamma channels. The asymptotic performance loss of the Alamouti-coded system with respect to the repetition-coded system is also quantified analytically.
TL;DR: The findings suggest that pointing error compensation is necessary as pointing errors can severely degrade the error rate and outage probability performance of an uncompensated system.
Abstract: An optical wireless communication system using subcarrier intensity modulation is analyzed for gamma-gamma turbulence channels with pointing errors We study the error rate performance of such a system employing M-ary phase-shift keying, differential phase-shift keying, and noncoherent frequency-shift keying Highly accurate error rate approximations are derived using a series expansion approach Furthermore, outage probability expressions are obtained for such a system Asymptotic error rate and outage probability analyses are also presented Our asymptotic analysis reveals some unique transmission characteristics of such a system Our findings suggest that pointing error compensation is necessary as pointing errors can severely degrade the error rate and outage probability performance of an uncompensated system
TL;DR: In this paper, a novel digital signal processing (DSP) scheme for quadrature duobinary (QDB) spectrum shaped polarization multiplexed Quadrature phase shift keying (PM-QPSK) based on multi-modulus blind equalizations (MMBE) is proposed and demonstrated with both simulation and experimental results.
Abstract: A novel digital signal processing (DSP) scheme for quadrature duobinary (QDB) spectrum shaped polarization multiplexed quadrature phase shift keying (PM-QPSK) based on multi-modulus blind equalizations (MMBE) is proposed and demonstrated with both simulation and experimental results. The key algorithms for this novel digital signal processing scheme include the cascaded multi-modulus algorithm (CMMA) for blind polarization de-multiplexing, multi-modulus QPSK partitioning frequency offset estimation (FOE) and two stage carrier phase recovery (CPR) with maximum likelihood phase estimation. The final signal is detected by maximum-likelihood sequence detection (MLSD) for data BER measurement. It shows that CMMA have better frequency response performance compared with CMA for noise compression. The performances of FOE and CPR are also investigated with different spectrum shaping bandwidth, group size and laser linewidth. Finally, the feasibility of the proposed digital signal processing scheme is demonstrated by the experiment of 112 Gb/s QDB spectrum shaped PM-QPSK signal with a 25 GHz bandwidth waveshaper for Nyquist WDM channels.
TL;DR: In this paper, a chromatic dispersion (CD) estimation technique was proposed by using the auto-correlation of signal power waveform for DSP-based coherent systems, which is applicable to single-carrier phase-shift keyed (PSK) and quadrature-amplitude modulation (QAM) systems.
Abstract: We propose a chromatic dispersion (CD) estimation technique by using the auto-correlation of signal power waveform for DSP based coherent systems. For single-carrier polarization-division-multiplexed (PDM) systems assuming Gaussian pulse shapes, we analytically show that the auto-correlation of signal power waveform contains a peak whose location is indicative of the accumulated CD and is insensitive to amplified spontaneous emission (ASE) noise, laser frequency offset, laser phase noise and first-order polarization-mode dispersion (PMD) and applicable to single-carrier phase-shift keyed (PSK) and quadrature-amplitude modulation (QAM) systems. As a linear scan of a preset range of CD is not needed, the number of symbols of the proposed technique is dramatically reduced. Simulation results show that to estimate the link CD for 112 Gb/s PDM-QPSK and 224 Gb/s PDM-16-QAM systems, 8192 symbols are sufficient for NRZ/RZ pulse shapes and 32768 symbols are sufficient for root-raised-cosine pulse shapes with the roll-off factor as low as 0.1 with estimation error below 175 ps/nm and 400 ps/nm, respectively.
TL;DR: The average bit error rate of the considered cooperative scheme for binary phase shift keying constellation over Rayleigh fading channels is derived and analytical diversity order of the beamforming and combining based DF MIMO relay system is obtained, for some special cases.
Abstract: In this paper, decode-and-forward (DF) based cooperation in a multiple antenna based wireless communication system is studied. In particular, we address the problem of beamforming and combining in a DF multiple-input multiple-output (MIMO) relay network with transmission path selection. A maximum eigenvalue based criterion is used for selection of best transmission path between source and destination nodes. We derive the average bit error rate of the considered cooperative scheme for binary phase shift keying constellation over Rayleigh fading channels. In addition, analytical diversity order of the beamforming and combining based DF MIMO relay system is obtained, for some special cases.
TL;DR: Numerical results show that for a system using QPSK under the frequent heavy shadowed fading condition, the diversity gain can be obtained at the SEP of 10-1 with respect to the direct transmission, when only one relay is used.
Abstract: In this paper, we study the Symbol Error Probability (SEP) performance of a hybrid/integrated satellite-terrestrial cooperative network. In particular, we focus on the case of mobile relays that forward the satellite signal to a masked mobile destination node. The Selective Decode-and-Forward (SDF) transmission scheme is implemented and only the relay nodes which can successfully decode the satellite message are selected to retransmit the signal. The destination node exploits the spatial diversity advantages by implementing a typical Maximum Ratio Combining (MRC) technique. The closed-form expressions for the exact average SEP of the arbitrary M-ary phase shift keying and M-ary quadrature amplitude modulation signaling with MRC diversity reception over independent but not necessarily identically distributed fading channels are derived using a Moment Generating Function (MGF) approach. These closed-form expressions are represented in terms of a finite sum of Lauricella hypergeometric functions. The analytical expressions show excellent agreement with the simulation results. Numerical results show that for a system using QPSK under the frequent heavy shadowed fading condition, the diversity gain of approximately 7 dB can be obtained at the SEP of 10-1 with respect to the direct transmission, when only one relay is used. It increases to around 12 dB in the case of 3 relays.
TL;DR: In this article, the first field transmission of 8 × 216.8-Gb/s Nyquist wavelength-division-multiplexing (N-WDM) signals over 1750-km G.652 fiber consisting of 950-km real and 800-km lab fibers with erbium-doped fiber amplifier (EDFA)-only amplification was realized.
Abstract: We have realized the first field transmission of 8 × 216.8-Gb/s Nyquist wavelength-division-multiplexing (N-WDM) signals over 1750-km G.652 fiber consisting of 950-km real and 800-km lab fibers with erbium-doped fiber amplifier (EDFA)-only amplification. The average loss per span is 21.6 dB. Each channel is modulated with 54.2-Gbaud (216.8-Gb/s) polarization-division-multiplexing carrier-suppressed return-to-zero quadrature-phase-shift-keying (PDM-CSRZ-QPSK) data on a 50-GHz grid giving a record spectral efficiency (SE) of 4 b/s/Hz. Digital post filtering and 1-bit maximum likelihood sequence estimation (MLSE) are introduced into the offline digital signal processing (DSP) at the receiver to suppress noise, linear crosstalk and filtering effects. We have also investigated the co-transmission of 200 G PDM-CSRZ-QPSK and 200 G PDM 16-ary quadrature-amplitude-modulation (PDM-16 QAM) signals on a 50-GHz grid, and found that PDM-CSRZ-QPSK signals have better bit-error-rate (BER) performance for both back-to-back and 700-km transmission cases. Meanwhile, PDM-16 QAM signals are subject to larger crosstalk from the neighboring Nyquist QPSK channels.
TL;DR: In this article, the design of amplitude phase-shift keying (APSK) constellations for a coherent fiber-optical communication system where nonlinear phase noise (NLPN) is the main system impairment is studied.
Abstract: We study the design of amplitude phase-shift keying (APSK) constellations for a coherent fiber-optical communication system where nonlinear phase noise (NLPN) is the main system impairment. APSK constellations can be regarded as a union of phase-shift keying (PSK) signal sets with different amplitude levels. A practical two-stage (TS) detection scheme is analyzed, which performs close to optimal detection for high enough input power. We optimize APSK constellations with 4, 8, and 16 points in terms of symbol error probability (SEP) under TS detection for several combinations of input power and fiber length. For 16 points, performance gains of 3.2 dB can be achieved at a SEP of 10-2 compared to 16-QAM by choosing an optimized APSK constellation. We also demonstrate that in the presence of severe nonlinear distortions, it may become beneficial to sacrifice a constellation point or an entire constellation ring to reduce the average SEP. Finally, we discuss the problem of selecting a good binary labeling for the found constellations.
TL;DR: In this paper, a widely-integrated widely-tunable optical homodyne receiver with 40 Gbaud/s data rate was reported by using photonic and electronic integration, and the receiver was realized within a size of 10 × 10 mm2.
Abstract: In this paper, a highly-integrated widely-tunable optical homodyne receiver is reported with 40 Gbaud/s data rate. By using photonic and electronic integration, the receiver is realized within a size of 10 × 10 mm2, and the system is very robust and resistive to environmental changes. An integrated photonic coherent receiver circuit is demonstrated with 35 GHz photodetector bandwidth, and the integrated local oscillator (LO) laser covers a 40 nm range. The electronic IC (EIC) has a working frequency up to 50 GHz. The feedback loop is carefully analyzed and designed, and the experimental results show > 1.1 GHz loop bandwidth, which matches the design. The hold-in range is measured to be > 15 GHz. The phase noise of the transmitting laser has been cloned to the LO laser quite well, and both the linewidth measurement and phase noise measurement show no observable cross talk between binary phase shift keying (BPSK) data and the optical phase-locked loop (OPLL). Error free ( bit error rate <; 10-12) is achieved up to 35 Gbit/s. The system consumes 3 Watts of power.
TL;DR: A highly filtering-tolerant multi-modulus equalization (MMEQ) process for very aggressively spectrum-shaped 9-ary quadrature-amplitude-modulation (9-QAM)-like polarization division multiplexing quadratures phase shift keying (PDM-QPSK) signal to achieve 400-Gb/s wavelength-division-multiplexing (WDM) channels on the 100-GHz grid for ultra-long-haul reach and
Abstract: We experimentally demonstrate a highly filtering-tolerant multi-modulus equalization (MMEQ) process for very aggressively spectrum-shaped 9-ary quadrature-amplitude-modulation (9-QAM)-like polarization division multiplexing quadrature phase shift keying (PDM-QPSK) signal to achieve 400-Gb/s wavelength-division-multiplexing (WDM) channels on the 100-GHz grid for ultra-long-haul reach and high tolerance of the filter narrowing effect caused by reconfigurable optical add-drop multiplexers (ROADMs). We successfully transmitted 8 channels 480-Gb/s super-Nyquist (channel occupancy much less than signal baud rate) WDM signals at 100-GHz grid over 25 × 200 km conventional single-mode fiber-28 (SMF-28) with post Raman amplification and 25 ROADMs at a net spectral efficiency (SE) of 4b/s/Hz, after excluding the 20% soft-decision forward-error-correction (FEC) overhead. The system performance is significantly enhanced by the MMEQ based on 9-QAM-like constellations compared to the conventional 4 point QPSK constellation. A record transmission distance over conventional SMF-28 with a large number of ROADMs is firstly reported on the 400-Gb/s channels at 100-GHz grid.
TL;DR: In this paper, the performance of a free space optical (FSO) communication system is analyzed by considering heavy atmospheric losses such as scattering, absorption, channel fading and misalignment fading.
TL;DR: In this article, an integrated silicon Mach-Zehnder modulator (MZM) was used for advanced modulation formats despite the nonlinear dependence of refractive index change with applied voltage in the free-carrier depletion modulator.
Abstract: Silicon photonics which is compatible with mature complementary metal oxide semiconductor (CMOS) fabrication process has been extensively demonstrated for monolithic integration of photonic and electrical circuits. We show that an integrated silicon Mach-Zehnder modulator (MZM) may be used for advanced modulation formats despite the nonlinear dependence of refractive index change with applied voltage in the free-carrier depletion modulator. We experimentally demonstrated the use of a silicon MZM for direct detection optical orthogonal frequency division multiplexing (DDO-OFDM) modulation with advanced data formats of quadrature phase-shift keying (QPSK), 8 phase-shift keying (8PSK) and 16-quadrature amplitude modulation (16-QAM). The measured bit error rate performance of the back-to-back and 50 km single mode fiber transmission of each format is well below the forward error correction limit.
Patent•
08 Nov 2013
TL;DR: In this paper, the phase of a modulation constellation is determined by examining the energy of the I and Q components after Fast Fourier Transform (FFT) in a signal field.
Abstract: Methods and systems for communicating in a wireless network may distinguish different types of packet structures by modifying the phase of a modulation constellation, such as a binary phase shift keying (BPSK) constellation, in a signal field. Receiving devices may identify the type of packet structure associated with a transmission or whether the signal field is present by the phase of the modulation constellation used for mapping for the signal field. In one embodiment, the phase of the modulation constellation may be determined by examining the energy of the I and Q components after Fast Fourier Transform. Various specific embodiments and variations are also disclosed.
TL;DR: A joint relay selection and power allocation (RS-PA) scheme is proposed to improve the symbol error probability (SEP) of the TWR network using BPSK modulation under the total power constraint.
Abstract: We consider a two-way relay (TWR) network with multiple relays, where the relays adopt physical layer network coding based on decode-and-forward. A joint relay selection and power allocation (RS-PA) scheme is proposed to improve the symbol error probability (SEP) of the TWR network using BPSK modulation under the total power constraint. For the proposed scheme and the benchmark scheme performing RS without PA, the average SEP of the TWR network is derived analytically and confirmed with simulation results. It is shown that the proposed scheme provides an asymptotic SNR gain of about 1.76 dB over the benchmark scheme at the same diversity order.
TL;DR: This work proposes a blind modulation classification algorithm when the channel coefficient, the noise power and the energy of the transmitted signal are unknown at the receiver and evaluates the unknown parameters using the iterative expectation maximization algorithm.
Abstract: We propose a blind modulation classification algorithm when the channel coefficient, the noise power and the energy of the transmitted signal are unknown at the receiver. First, under each candidate modulation scheme, we evaluate the unknown parameters using the iterative expectation maximization algorithm. Modulation classification is then accomplished by minimizing the distance between the log-likelihood of the received data and the expected log-likelihood under each candidate modulation scheme. Results are presented from simulations in terms of detection probability vs. SNR for the class of BPSK, QPSK, 16QAM and 64QAM modulation schemes. The results show a significant improvement over QHLRT and are very close to the upper bound ALRT-UB [1].
TL;DR: It is analytically shown that the proposed ML and PL decoders achieve maximum possible diversity in the multi-antenna cooperative system with a single relay.
Abstract: We derive a maximum-likelihood (ML) decoder for decode-and-forward (DF) based multiple-input-multiple-output (MIMO) cooperative systems having an equal number of antennas at the source and relay nodes, and utilizing an arbitrary complex-valued M-ary constellation. The DF-based MIMO cooperative system considered in this paper utilizes orthogonal space-time block codes (OSTBCs) for the transmission of data of the source to the destination. To reduce the decoding complexity, a suboptimal piecewise linear (PL) decoder is also derived, which performs close to the ML decoder. The proposed ML and PL decoders are applicable to arbitrary complex-valued M -ary constellations and require the destination node to possess knowledge of the channel statistics of the source-relay (S-R) links, whereas the existing decoder of multi-antenna-based DF cooperative systems needs to know the exact channel coefficients of the S-R link at the destination. The proposed decoders outperform an amplify-and-forward (AF)-protocol-based multi-antenna cooperative system. We obtain an expression of the average probability of error of the proposed PL decoder using an M-phase-shift keying (M-PSK) constellation and a single MIMO relay. The approximate symbol error rate (SER) of the proposed PL decoder is derived with multiple MIMO relays, M-PSK constellation, and asymptotically high signal-to-noise ratio (SNR) of the S-R links. It is analytically shown that the proposed ML and PL decoders achieve maximum possible diversity in the multi-antenna cooperative system with a single relay.
TL;DR: It is shown that the complex plane can be partitioned into two regions: a region in which any network coding map which satisfies the exclusive law gives the same best performance and a regions in which the choice of the network coding maps affects the performance.
Abstract: The design of modulation schemes for the physical layer network-coded two-way relaying scenario is considered with a protocol which employs two phases: multiple access (MA) phase and broadcast (BC) phase. It was observed by Koike-Akino et al. that adaptively changing the network coding map used at the relay according to the channel conditions greatly reduces the impact of MA interference which occurs at the relay during the MA phase and all these network coding maps should satisfy a requirement called the exclusive law. We show that every network coding map that satisfies the exclusive law is representable by a Latin Square and conversely, that this relationship can be used to get the network coding maps satisfying the exclusive law. The channel fade states for which the minimum distance of the effective constellation at the relay become zero are referred to as the singular fade states. For M- PSK modulation ( M any power of 2), it is shown that there are (M2/4- M/2+1 )M singular fade states. Also, it is shown that the constraints which the network coding maps should satisfy so that the harmful effects of the singular fade states are removed, can be viewed equivalently as partially filled Latin Squares (PFLS). The problem of finding all the required maps is reduced to finding a small set of maps for M- PSK constellations ( M any power of 2), obtained by the completion of PFLS. Even though the completability of M ×M PFLS using M symbols is an open problem, specific cases where such a completion is always possible are identified and explicit construction procedures are provided. Having obtained the network coding maps, the set of all possible channel realizations (the complex plane) is quantized into a finite number of regions, with a specific network coding map chosen in a particular region. It is shown that the complex plane can be partitioned into two regions: a region in which any network coding map which satisfies the exclusive law gives the same best performance and a region in which the choice of the network coding map affects the performance. The quantization thus obtained analytically, leads to the same as the one obtained using computer search for 4-PSK signal set by Koike-Akino et al. when specialized for Simulation results show that the proposed scheme performs better than the conventional exclusive-OR (XOR) network coding and in some cases outperforms the scheme proposed by Koike-Akino et al.
TL;DR: In this article, the authors considered a multiuser system where an arbitrary number of users communicate with a distributed receive array over independent Rayleigh fading paths and provided approximate distributions for the output SNR of a ZF receiver and the output signal to interference plus noise ratio (SINR) of an MMSE receiver.
Abstract: Consider a multiuser system where an arbitrary number of users communicate with a distributed receive array over independent Rayleigh fading paths. The receive array performs minimum mean squared error (MMSE) or zero forcing (ZF) combining and perfect channel state information is assumed at the receiver. This scenario is well-known and exact analysis is possible when the receive antennas are located in a single array. However, when the antennas are distributed, the individual links all have different average signal to noise ratio (SNRs) and this is a much more challenging problem. In this paper, we provide approximate distributions for the output SNR of a ZF receiver and the output signal to interference plus noise ratio (SINR) of an MMSE receiver. In addition, simple high SNR approximations are provided for the symbol error rate (SER) of both receivers assuming M-PSK or M-QAM modulations. These high SNR results provide array gain and diversity gain information as well as a remarkably simple functional link between performance and the link powers.
Patent•
18 Dec 2013
TL;DR: In this paper, a method for recognizing digital modulating signals in non-Gaussian noise was proposed, which solves the problem that signals in Alpha stable distribution noise do not have second or higher order statistics.
Abstract: The invention discloses a method for effectively recognizing digital modulating signals in non-Gaussian noise Non-linear transformation is performed on a received signal s(t); the generalized first-order cyclic cumulant and the generalized second-order cyclic cumulant of the received signal s(t) are calculated, and a 2FSK signal is recognized by calculating the characteristic parameters of the received signal s(t) and utilizing a minimum mean square error classifier; the generalized second-order cyclic cumulant of the received signal s(t) is calculated, and by calculating the characteristic parameters of the received signal s(t) and utilizing the minimum mean square error classifier, the number of spectral peaks of a generalized cyclic cumulant magnitude spectrum is detected so that a BPSK signal and an MSK signal can be recognized; the generalized fourth-order cyclic cumulant of the received signal s(t) is calculated, and a QPSK signal, an 8PSK signal and other signals are recognized through the calculated characteristic parameters and the minimum mean square error classifier The method for effectively recognizing digital modulating signals in non-Gaussian noise solves the problem that signals in Alpha stable distribution noise do not have second or higher order statistics, effectively recognizes the digital modulating signals and can be used for recognizing the modulation mode of the digital modulating signals in the Alpha stable distribution noise