Showing papers on "Phase-shift keying published in 2007"
TL;DR: Results of a 42.8Gbit/s nonlinear transmission experiment, using polarization multiplexed QPSK data at 10.7GBaud, with 4 bits per symbol is presented, which allows the digital coherent receiver to be compensated digitally after transmission over 6400km of standard single mode fiber.
Abstract: Digital signal processing (DSP) combined with a phase and polarization diverse coherent receiver is a promising technology for future optical networks. Not only can the DSP be used to remove the need for dynamic polarization control, but also it may be utilized to compensate for nonlinear and linear transmission impairments. In this paper we present results of a 42.8Gbit/s nonlinear transmission experiment, using polarization multiplexed QPSK data at 10.7GBaud, with 4 bits per symbol. The digital coherent receiver allows 107,424 ps/nm of chromatic dispersion to be compensated digitally after transmission over 6400km of standard single mode fiber.
377 citations
TL;DR: Tight approximations for both the post-processing SNR distribution and bit error rate for MIMO ZF receivers with M-QAM and M-PSK modulated signals are derived in closed-form by modeling the estimation error as independent complex Gaussian random variables.
Abstract: By employing spatial multiplexing, multiple-input multiple-output (MIMO) wireless antenna systems provide increases in capacity without the need for additional spectrum or power. Zero-forcing (ZF) detection is a simple and effective technique for retrieving multiple transmitted data streams at the receiver. However the detection requires knowledge of the channel state information (CSI) and in practice accurate CSI may not be available. In this letter, we investigate the effect of channel estimation error on the performance of MIMO ZF receivers in uncorrelated Rayleigh flat fading channels. By modeling the estimation error as independent complex Gaussian random variables, tight approximations for both the post-processing SNR distribution and bit error rate (BER) for MIMO ZF receivers with M-QAM and M-PSK modulated signals are derived in closed-form. Numerical results demonstrate the tightness of our analysis
351 citations
TL;DR: The analysis shows that the optimum power allocation at different nodes follows a certain ordering, and that the power-allocation scheme at high SNR does not depend on the channel quality of the direct link between the source and the destination.
Abstract: In this paper, a class of cooperative communication protocols with arbitrary N-relay nodes is proposed for wireless networks, in which each relay coherently combines the signals received from m (1lesmlesN-1) previous relays in addition to the signal from the source. Exact symbol-error-rate (SER) expressions for an arbitrary N-node network employing M'ary phase-shift-keying (MPSK) modulation or quadrature-amplitude modulation (QAM) are provided for the proposed class of protocols. Further, approximate expressions for the SER are derived and shown to be tight at high enough signal-to-noise ratio (SNR). Our analysis reveals an interesting result: The class of cooperative protocols shares the same asymptotic performance at high enough SNR and does not depend on m, the number of previous nodes involving in coherent detection, hence, the asymptotic performance of a simple cooperative scenario in which each relay combines the signals from the source and the previous relay is exactly the same as that for a much more complicated scenario in which each relay combines the signals from the source and all the previous relays. The theoretical results also confirm that full diversity equal to the number of cooperating nodes is indeed achievable by the proposed protocols. Finally, we formulate a power-allocation problem in order to minimize the SER of the system. The analysis shows that the optimum power allocation at different nodes follows a certain ordering, and that the power-allocation scheme at high SNR does not depend on the channel quality of the direct link between the source and the destination. Closed-form solutions for the optimal power-allocation problem are provided for some network topologies. Simulation results confirm our theoretical analysis
344 citations
TL;DR: In this article, an optical intradyne receiver experiment with frequency estimation is reported. But this experiment was performed prior to block phase estimation or other phase recovery techniques, for a much higher frequency difference between transmit laser and local oscillator laser.
Abstract: We report on an optical intradyne receiver experiment with frequency estimation. Frequency estimation allows, if performed prior to block phase estimation or other phase recovery techniques, for a much higher frequency difference between transmit laser and local oscillator laser. We demonstrate the feasibility of our approach in a 20-Gb/s quadrature phase-shift keying experiment
289 citations
22 Apr 2007
TL;DR: It is shown that for COFDM (coded OFDM) with QPSK (quadrature phase shift keying) modulation and a single LED, a BER of 2 times 10-5 is achieved for a distance of 90 cm between transmitter and receiver.
Abstract: White LEDs are set to penetrate many areas of everyday life. An interesting property of these devices (in addition to their lightening capabilities) is that they can be utilised for data transmission. In the past, primarily OOK (on-off keying) has been used for digital data modulation of such devices. OOK imposes limitations on the achievable data rates. Therefore, in this paper OFDM is considered in combination with higher order modulation schemes. A hardware demonstrator with an entire link chain (transmitter and receiver) is developed and measured BER (bit error ratio) results are reported. The system uses pilot sub-carriers to correct frequency synchronisation errors, training sequences for channel estimation and time synchronisation routines. Forward error correction (FEC) coding is used. It is shown that for COFDM (coded OFDM) with QPSK (quadrature phase shift keying) modulation and a single LED, a BER of 2 times 10-5 is achieved for a distance of 90 cm between transmitter and receiver.
243 citations
TL;DR: A novel, simple and tight approximation for the Gaussian Q-function and its integer powers is presented, and an accuracy improvement is achieved over the whole range of positive arguments.
Abstract: We present a novel, simple and tight approximation for the Gaussian Q-function and its integer powers. Compared to other known closed-form approximations, an accuracy improvement is achieved over the whole range of positive arguments. The results can be efficiently applied in the evaluation of the symbol error probability (SEP) of digital modulations in the presence of additive white Gaussian noise (AWGN) and the average SEP (ASEP) over fading channels. As an example we evaluate in closed-form the ASEP of differentially encoded QPSK in Nakagami-m fading.
242 citations
24 Jun 2007
TL;DR: This paper considers the extreme case of only 1-bit ADC for each receive signal component, and shows that QPSK is, up to the second order, the best among all distributions with independent components in the low signal-to-noise ratio regime.
Abstract: We study the performance of multi-input multi-output (MIMO) channels with coarsely quantized outputs in the low signal-to-noise ratio (SNR) regime, where the channel is perfectly known at the receiver. This analysis is of interest in the context of ultra-wideband (UWB) communications from two aspects. First the available power is spread over such a large frequency band, that the power spectral density is extremely low and thus the SNR is low. Second the analog-to-digital converters (ADCs) for such high bandwidth signals should be low-resolution, in order to reduce their cost and power consumption. In this paper we consider the extreme case of only 1-bit ADC for each receive signal component. We compute the mutual information up to second order in the SNR and study the impact of quantization. We show that, up to first order in SNR, the mutual information of the 1-bit quantized system degrades only by a factor of 2/pi compared to the system with infinite resolution independent of the actual MIMO channel realization. With channel state information (CSI) only at receiver, we show that QPSK is, up to the second order, the best among all distributions with independent components. We also elaborate on the ergodic capacity under this scheme in a Rayleigh flat-fading environment.
218 citations
TL;DR: An upper bound on BER is derived for optical communication systems employing convolutional codes and subcarrier BPSK modulation and interleaving is employed to overcome memory effect in atmospheric turbulence channels.
Abstract: This paper studies optical communications using subcarrier phase-shift keying (PSK) intensity modulation through atmospheric turbulence channels. The bit error rate (BER) is derived for optical communication systems employing with 00K or subcarrier PSK intensity modulation. It is shown that a ${\rm BER}=10^{-6}$ and a scintillion level $\sigma=0.1$ , an optical communication system employing subcarrier BPSK is 3 dB better than a comparable system using fixed threshold 00K. When $\sigma=0.2$ , an optical communication system employing subcarrier BPSK achieves a ${\rm BER}=10^{-6}$ at SNR 13.7 dB, while the BER of a comparable system employing 00K can never be less than ${\hbox{10}}^{-4}$ . Convolutional codes are discussed for optical communication through atmospheric turbulence channels. Interleaving is employed to overcome memory effect in atmospheric turbulence channels. An upper bound on BER is derived for optical communication systems employing convolution codes and subcarrier BPSK modulation.
213 citations
Patent•
06 Nov 2007TL;DR: In this article, the peak to average (PAR) back off value is used to determine the transmission power and rate for SIMO and MIMO transmissions, and the power allocation algorithm for different UL-MIMO schemes is described.
Abstract: A method for a wireless communication includes receiving or storing a peak to average (PAR) back off value; and applying the PAR back off value to determine the transmission power and rate for SIMO and MIMO transmissions. In one aspect, the PAR back off value is at least partially based on modulation type. In another aspect, the PAR back off value is more for higher order QAM than for QPSK. The power allocation algorithm for different UL MIMO schemes is described as follows. For MIMO without antenna permutation (e.g. per antenna rate control), different PAR back off values are considered for different data streams. For MIMO with antenna permutation or other unitary transformation such as virtual antenna mapping or precoding, the PAR back off are determined based on combined channel. The transmission data rate depends on power and also the receiver algorithms such as a MMSE receiver or MMSE-SIC receiver.
200 citations
TL;DR: This method can recognize classical single- carrier modulations, as well as orthogonal frequency-division multiplexing modulations such as discrete mul- titone that is used for asymmetricdigital subscriber line and very high speed digital subscriber line standards and for power-line carrier transmissions.
Abstract: This paper presents a method for the automatic classification of digital modulations without a priori knowledge of the signal parameters. This method can recognize classical single- carrier modulations such as M-ary phase-shift keying, M-ary frequency-shift keying, M-ary amplitude-shift keying, and M-ary quadrature amplitude modulation, as well as orthogonal frequency-division multiplexing modulations such as discrete mul- titone that is used for asymmetric digital subscriber line and very high speed digital subscriber line standards and for power-line carrier transmissions. After identification of the modulation type, the method automatically estimates some parameters characterizing the modulation. To evaluate the method performance, several simulations have been carried out in different operating conditions that should be particularly critical by varying the values of signal- to-noise ratio and the main parameters of each identifiable modulation. To assess the advantages, comparison with other classification methods has been given. To validate the assumption that is made, experimental tests have been performed.
124 citations
TL;DR: In this article, the maximum-likelihood (ML) decision boundaries and symbol error rate (SER) for phase-shift keying and differential phase-keying systems with coherent and differentially coherent detection are presented.
Abstract: In optical fiber transmission systems using inline amplifiers, the interaction of a signal and amplifier noise through the Kerr effect leads to nonlinear phase noise that can impair the detection of phase-modulated signals. We present analytical expressions for the maximum-likelihood (ML) decision boundaries and symbol-error rate (SER) for phase-shift keying and differential phase-shift keying systems with coherent and differentially coherent detection, respectively. The ML decision boundaries are in the form thetas(r) = c2r2 + c1r + c0, where thetas and r are the phase and the amplitude of the received signal, respectively. Using the expressions for the SER, we show that the impact of phase error from carrier synchronization is small, particularly for transoceanic links. For modulation formats such as 16-quadrature amplitude modulation, we propose various transmitter and receiver phase rotation strategies such that the ML detection is well approximated by using straight-line decision boundaries. The problem of signal constellation design for optimal SER performance is also studied for a system with four signal points.
27 Nov 2007
TL;DR: An all-digital UWB transmitter architecture that exploits the low duty cycle of impulse-radio UWB to achieve ultra-low power consumption and supports the IEEE 802.15.4a standard is proposed.
Abstract: We propose an all-digital UWB transmitter architecture that exploits the low duty cycle of impulse-radio UWB to achieve ultra-low power consumption. The design supports the IEEE 802.15.4a standard and is demonstrated for its mandatory mode. A digitally controlled oscillator produces the RF carrier between 3 and 10 GHz. It is embedded in a phase-aligned frequency-locked loop that starts up in 2 ns and thus exploits the signal duty cycle that can be as low as 3%. A fully dynamic modulator shapes the BPSK symbols in discrete steps at the 499.2 MHz chip rate as required by the standard. The transmitter can operate in any 499.2 MHz band of the standard between 3.1 and 10 GHz, and the generated signal fulfills the emission spectral mask. The jitter accumulation over a burst is below 6 psRMS, which is within specifications. The transmitter was realized in a 1 V 90 nm digital CMOS technology, and its power consumption drawn from a 1 V supply is from 0.65 mW at 3.1 GHz to 1.4 mW at 10 GHz for a 1 Mb/s data rate.
TL;DR: Low-density parity-check (LDPC) coded optical orthogonal frequency division multiplexing (OFDM) is shown to significantly outperform LDPC coded on-off keying (OOK) over the atmospheric turbulence channel in terms of both coding gain and spectral efficiency.
Abstract: Low-density parity-check (LDPC) coded optical orthogonal frequency division multiplexing (OFDM) is shown to significantly outperform LDPC coded on-off keying (OOK) over the atmospheric turbulence channel in terms of both coding gain and spectral efficiency. In the regime of strong turbulence at a bit-error rate of 10-5, the coding gain improvement of the LDPC coded single-side band unclipped-OFDM system with 64 sub-carriers is larger than the coding gain of the LDPC coded OOK system by 20.2dB for quadrature-phase-shift keying (QPSK) and by 23.4dB for binary-phase-shift keying (BPSK).
TL;DR: In this article, a symmetric pump phase-sensitive amplification (SP-PSA) was used for phase regeneration of a phase-noise degraded nonreturn-to-zero differential phase-shift keying signal, significantly improving signal quality.
Abstract: Symmetric-pump phase-sensitive amplification (SP-PSA) is investigated experimentally. Symmetric pump waves are derived using carrier-suppressed return-to-zero modulation. The SP-PSA is used for phase regeneration of a phase-noise degraded nonreturn-to-zero differential phase-shift keying signal, significantly improving signal quality
TL;DR: The feasibility of the modulation format conversion from NRZ-OOK to RZ-8-levels PSK by numerical simulation is demonstrated and the error-free operation of NRz-OOK/RZ- binary PSK conversion is experimentally demonstrated.
Abstract: We propose an all-optical modulation format conversion scheme from non-return-to-zero on-off-keying (NRZ-OOK) to return-to-zero (RZ) multiple-level phase-shift-keying (PSK) based on nonlinearity in optical fiber. The proposed conversion scheme is numerically investigated and experimentally demonstrated. We experimentally demonstrate error-free operation of NRZ-OOK/RZ- binary PSK conversion at 10.7 Gb/s. The operation of the NRZ-OOK/RZ-quadrature PSK conversion is shown by eye opening after balanced receiving at a symbol rate of 10.7 Gsymbol/s. In addition, we demonstrate the feasibility of the modulation format conversion from NRZ-OOK to RZ-8-levels PSK by numerical simulation.
Proceedings Article•
25 Mar 2007TL;DR: In this article, the measured WDM performance and PMD tolerance of a coherent 40Gbit/s DP-QPSK transceiver at 50GHz minimum channel spacing in a 40-channel, 40-span test bed comprised of 3200 km of uncompensated G.652 fiber are reported.
Abstract: We report the measured WDM performance and PMD tolerance of a coherent 40Gbit/s DP-QPSK transceiver at 50-GHz minimum channel spacing in a 40-channel, 40-span test bed comprised of 3200 km of uncompensated G.652 fiber.
TL;DR: Passive time reversal communications is described which enables multiple users to send information simultaneously to the time reversal array over a common bandwidth channel.
Abstract: A recent paper (Song , IEEE Journal of Oceanic Engineering, vol. 31, no. 2, pp. 170-178, 2006) demonstrated multiple-input-multiple-output (MIMO) communications in shallow water using active time reversal where the time reversal array (i.e., base station) sent different messages to multiple users simultaneously over a common bandwidth channel. Passive time reversal essentially is equivalent to active time reversal with the communications link being in the opposite direction. This paper describes passive time reversal communications which enables multiple users to send information simultaneously to the time reversal array. Experimental results at 3.5 kHz with a 1-kHz bandwidth demonstrate that as many as six users can transmit information over a 4-km range in a 120-m-deep water using quaternary phase-shift keying (QPSK) modulation, achieving an aggregate data rate of 6 kb/s. Moreover, the same data rate has been achieved at 20-km range by three users using 16 quadrature amplitude modulation (16-QAM).
TL;DR: Close-form expressions for the bit error rate (BER) performance of space-frequency block coded OFDM (SFBC-OFDM) systems are derived and evaluated for frequency-selective fading channels, and the effects of channel estimation errors on the BER performance are studied.
Abstract: Closed-form expressions for the bit error rate (BER) performance of space-frequency block coded OFDM (SFBC-OFDM) systems are derived and evaluated for frequency-selective fading channels. In the performance analysis, both M-ary phase shift keying (MPSK) and M-ary quadrature amplitude modulation (MQAM) are considered, and the effects of channel estimation errors on the BER performance are studied. Numerical results and comparisons are provided for several forms of SFBC-OFDM. It is shown that the results obtained from the closed-form formulae are very close to the ones using the exact expressions and to simulation results of the SFBC-OFDM model. The BER deterioration that results from channel estimation errors in the SFBC-OFDM systems is also illustrated. Using the provided results, the amount of degradation can be quantified.
01 Jul 2007
TL;DR: In this paper, the error performance of the FSO using a subcarrier intensity modulation (SIM) based on a binary phase shift keying scheme in clear but turbulent atmosphere is presented.
Abstract: Free-space optical communications (FSO) propagated over a clear atmosphere suffers from irradiance fluctuation caused by small but random atmospheric temperature fluctuations. This results in decreased signal- to-noise ratio and consequently impaired error performance. In this paper, the error performance of the FSO using a subcarrier intensity modulation (SIM) based on a binary phase shift keying scheme in clear but turbulent atmosphere is presented. To evaluate the system error performance in turbulence regimes from weak to strong, the probability density function of the received irradiance after traversing the atmosphere is modelled using the gamma-gamma distribution and the effect of turbulence induced irradiance fluctuation is mitigated using spatial diversity.
TL;DR: In this letter, a BER study is presented for decode-and-forward (DF) relaying in independent but not identically distributed Rayleigh fading channels and it is shown that the analytic results are perfectly matched with the simulated ones.
Abstract: In this letter, a BER study is presented for decode-and-forward (DF) relaying in independent but not identically distributed Rayleigh fading channels. For an arbitrary number of relays, exact and closed-form expressions of the BER are provided for M-ary PAM, QAM and PSK, respectively. It is also shown that the analytic results are perfectly matched with the simulated ones
TL;DR: It turns out that the binary reflected Gray code (BRGC) is optimal for PSK and PAM systems whenever the target BEP is at most a few percent, which covers most systems of practical interest.
Abstract: The problem of finding the optimal labeling (bit-to-symbol mapping) of multilevel coherent phase shift keying (PSK), pulse amplitude modulation (PAM), and quadrature amplitude modulation (QAM) constellations with respect to minimizing the bit-error probability (BEP) over a Gaussian channel is addressed. We show that using the binary reflected Gray code (BRGC) to label the signal constellation results in the lowest possible BEP for high enough signal energy-to-noise ratios and analyze what is "high enough" in this sense. It turns out that the BRGC is optimal for PSK and PAM systems whenever the target BEP is at most a few percent, which covers most systems of practical interest. New and simple closed-form expressions are presented for the BEP of PSK, PAM, and QAM using the BRGC
TL;DR: It is experimentally demonstrated that in both decoded channels of the converted RZ-QPSK signal bit error rate (BER) curves show almost the same receiver sensitivity at a symbol-rate of 10.7 Gsymbol/s.
Abstract: A novel all-optical modulation format conversion from non-return-to-zero on-off-keying (NRZ-OOK) to return-to-zero quadrature-phase-shift-keying (RZ-QPSK) is proposed and experimentally demonstrated. The proposed format conversion scheme is based on parallel Mach-Zehnder interferometric (MZI) OOK/binary-PSK (BPSK) converters, consisting of integrated semiconductor optical amplifiers (SOAs). We experimentally demonstrate that in both decoded channels of the converted RZ-QPSK signal bit error rate (BER) curves show almost the same receiver sensitivity at a symbol-rate of 10.7 Gsymbol/s. In addition, a reasonable dispersion tolerance of the converted signal up to +295 ps/nm is observed. The numerical simulation based upon carrier rate equation verifies the experimental results.
01 Jan 2007
TL;DR: In this article, a 1.6-b/s/Hz long-haul transmission with a polarization-multiplexed return-to-zero differential quadrature phase-shift keying was proposed.
Abstract: We discuss high spectral efficient long-haul transmission using multilevel modulation formats. In particular, we investigate long-haul transmission with a 1.6-b/s/Hz spectral efficiency using polarization-multiplexed return-to-zero differential quadrature phase-shift keying. In an experimental demonstration, we show 40 times 85.6-Gb/s transmission with a 50-GHz channel spacing over 1700 km (18 times 94.5 km) of standard-single-mode fiber
TL;DR: A new non-data-aided estimate is proposed, which makes use of the sixth-order moment of the received data, and which can be tuned for a particular constellation in order to extend the usable range of SNR values.
Abstract: Signal-to-noise ratio (SNR) estimation is an important task in many digital communication systems. With nonconstant modulus constellations, the performance of the classical second- and fourth-order moments estimate is known to degrade with increasing SNR. A new non-data-aided estimate is proposed, which makes use of the sixth-order moment of the received data, and which can be tuned for a particular constellation in order to extend the usable range of SNR values. The advantage of the new method is especially significant for constellations with two different amplitude levels, e.g. 16-amplitude-and-phase-shift keying (16-APSK)
TL;DR: A transmission protocol that follows a two-stage model: transmission from source to relays in the first stage, followed by a simple relaying technique from relays to destination, for which the decoding complexity is independent of code size is shown.
Abstract: Distributed space-time coding is a mean of achieving diversity through cooperative communication in a wireless relay network. In this paper, we consider a transmission protocol that follows a two-stage model: transmission from source to relays in the first stage, followed by a simple relaying technique from relays to destination. The relays transmit a vector which is a transformation of the received vector by a relay-specific unitary transformation. We assume that the relays do not have any channel information, while the destination has only a partial-channel knowledge, by which we mean that destination knows only the relay-to-destination channel. For such a setup, we derive a Chernoff bound on the pairwise error probability and propose code design criteria. A second contribution is the differential encoding and decoding scheme for this setup, which is different from the existing ones. Furthermore, differential codes from cyclic division algebra are proposed that achieve full diversity. For our setup with two relays, a Generalized PSK code is shown to achieve full diversity, for which the decoding complexity is independent of code size
TL;DR: The DBOC concept might be useful to other satellite-based applications, when the available bandwidth is large enough, and the authors illustrate via several examples how to choose optimally the parameters of this new modulation family, according to different optimization criteria.
Abstract: An important aspect in designing the modulation scheme for various satellite systems, such as the modernized GPS and Galileo, is to obtain good spectral properties and suitable spectral shaping. For example, in the future satellite navigation systems, some of the main goals are: low interference with the existing GPS signals, good root-mean-square (RMS) bandwidth, good time resolution (in order to allow the separation between channel paths and to decrease the synchronization errors) etc. Starting from the recently proposed cosine- and sine-BOC modulation families for GPS and Galileo systems, we introduce a new, generalized family, denoted here by double-BOC (DBOC) modulation. We derive and analyze the properties of the power spectral densities (PSD) and autocorrelation functions (ACF) of the DBOC modulation with various orders, we show its relationship with BPSK, sine- and cosine-BOC modulations, and we illustrate via several examples how to choose optimally the parameters of this new modulation family, according to different optimization criteria. The examples are targeting at applications such as the design of suitable modulations for Galileo open service (OS) and public regulated service (PRS) signals, but the authors believe that the DBOC concept might be useful to other satellite-based applications, when the available bandwidth is large enough. Copyright © 2006 John Wiley & Sons, Ltd.
TL;DR: The mean square error of tracking of the LS MIMO channel estimator algorithm is derived as a closed-form function of the Doppler shift, forgetting factor, channel rank, and the length of training sequences, and it is concluded that in low Eb/No values, the number of transmitter antennas has negligible effect on the optimal value of the forgetting factor.
Abstract: In this paper, the tracking performance analysis of the least squares (LS) multiple-input multiple-output (MIMO) channel estimation and tracking algorithm is presented. MIMO channel estimation is a novel application of the LS algorithm that presents near-optimum performance by Karami and Shiva in 2003 and 2006. In this paper, the mean square error (MSE) of tracking of the LS MIMO channel estimator algorithm is derived as a closed-form function of the Doppler shift, forgetting factor, channel rank, and the length of training sequences. In the analysis, all training symbols are considered as randomly generated equal-power vectors on the unit circle, or in other words, phase-shift keying (PSK) signaling. By evaluating this function, some insights into the tracking behavior of the LS MIMO channel estimator are achieved. Then, the calculated tracking error is compared with the tracking error derived from Monte Carlo simulation for quaternary-PSK-based training signals to verify the validation of the presented analysis. Finally, the optimum forgetting factor is derived to minimize the error function, and it is shown that the optimum forgetting factor is highly dependent on the training length, Doppler shift, and Eb/No. Also, it is concluded that in low Eb/No values, the number of transmitter antennas has negligible effect on the optimal value of the forgetting factor.
24 Jun 2007
TL;DR: The proposed ESPAR antenna is capable of mapping phase-shift-keying (PSK) modulated symbols to be transmitted onto orthogonal basis functions on the wavevector domain of the multi-element antenna (MEA), instead of the traditional approach of sending different symbol streams in different locations on the antenna domain.
Abstract: In this paper the use of electronically steerable passive array radiator (ESPAR) antennas is introduced for achieving increased spectral efficiency characteristics in multiple-input, multiple-output (MIMO) systems using a single active element, and compact antennas. The proposed ESPAR antenna is capable of mapping phase-shift-keying (PSK) modulated symbols to be transmitted onto orthogonal basis functions on the wavevector domain of the multi-element antenna (MEA), instead of the traditional approach of sending different symbol streams in different locations on the antenna domain. In this way, different symbols are transmitted simultaneously towards different angles of departure at the transmitter side. We show that the proposed system, called beamspace-MIMO (BS-MIMO) can achieve performance characteristics comparable to traditional MIMO systems while using a single radio-frequency (RF) front-end and ESPAR antenna arrays of total length equal to lambda/8, for popular PSK modulation schemes such as binary-PSK (BPSK), quaternary-PSK (QPSK), as well as for their offset-PSK and differential-PSK variations.
TL;DR: In this article, a 6-Gbaud binary phase-shift keying WDM transmission with a 6GHz channel spacing was shown to achieve a Q-factor penalty of 2.8 dB compared to a single-channel transmission.
Abstract: Optical wavelength-division multiplexing (WDM) with channel spacing equal to the symbol rate is demonstrated. Coherent detection with subsequent digital signal processing is used for demultiplexing and demodulation. Experimental results for a 6-Gbaud binary phase-shift keying WDM transmission with a 6-GHz channel spacing achieve a Q-factor penalty of 2.8 dB compared to a single-channel transmission.
TL;DR: A coherent digital polarization diversity receiver for real-time polarization-multiplexed synchronous quadrature phase-shift keying transmission with distributed feedback lasers at a data rate of 2.8 Gb/s was presented in this article.
Abstract: This letter presents a coherent digital polarization diversity receiver for real-time polarization-multiplexed synchronous quadrature phase-shift keying transmission with distributed feedback lasers at a data rate of 2.8 Gb/s. The tolerance against fast polarization changes and polarization-dependent loss is evaluated for different filter widths in the carrier recovery circuit. The minimum achieved bit-error rate is 3.4 times 10-7.