ScholarBank@NUShttps://scholarbank.nus.edu.sgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Mon, 22 Jul 2019 00:33:30 GMT2019-07-22T00:33:30Z50321- MDPSK diversity receiver over Rayleigh fading channels with differential detection and nonidentical branch statisticshttps://scholarbank.nus.edu.sg/handle/10635/70895Title: MDPSK diversity receiver over Rayleigh fading channels with differential detection and nonidentical branch statistics
Authors: Fu, H.; Kam, P.Y.
Abstract: Independent, frequency nonselective, fast, Rayleigh diversity fading channels with nonidentical branch statistics are assumed. The optimum combining receiver structure for differential phase shift keying (DPSK) with differential detection is derived based on the maximum a posteriori probability criterion. Both explicit, closed-form bit error probability (BEP) expressions for 2-, 4- and 8-DPSK and simple Chernoff upper bounds to these BEP's are obtained for arbitrary order of diversity. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/708952006-01-01T00:00:00Z
- ML estimation of the frequency and phase in noisehttps://scholarbank.nus.edu.sg/handle/10635/70959Title: ML estimation of the frequency and phase in noise
Authors: Fu, H.; Kam, P.Y.
Abstract: The problem of estimating the frequency and carrier phase of a single sinusoid observed in additive, white, Gaussian noise is addressed. Much of the work in the literature considers maximum likelihood (ML) estimation. However, the ML estimator given by the location of the peak of a periodogram in the frequency domain [1] has a very high computational complexity. This paper derives an explicit structure of the ML estimator for data processing in the time domain, assuming only reasonably high signal-to-noise ratio. The result of this approximate ML estimator shows that both the phase and the magnitude of the noisy signal samples are utilized in the estimator, and the phase data alone as assumed in [2] and [3] is not a sufficient statistic. The sample-by-sample iterative processing nature of the estimator enables us to propose a novel, recursive phase-unwrapping algorithm that allows the estimator to be implemented efficiently. To facilitate the performance analysis, an improved, linearized observation model for the instantaneous signal phase that is more accurate than that of [2] and [3] is proposed. This improved model explains physically why the phase data are weighted by the magnitude information in the ML estimator. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/709592006-01-01T00:00:00Z
- Performance of optimum and suboptimum combining diversity reception for binary DPSK over independent, nonidentical Rayleigh fading channelshttps://scholarbank.nus.edu.sg/handle/10635/71415Title: Performance of optimum and suboptimum combining diversity reception for binary DPSK over independent, nonidentical Rayleigh fading channels
Authors: Fu, H.; Kam, P.Y.
Abstract: This paper is concerned with the error performance analysis of binary differential phase shift keying with differential detection over the nonselective, Rayleigh fading channel with combining diversity reception. Space antenna diversity reception is assumed. The diversity branches are independent, but have nonidentically distributed statistics. The fading process in each branch is assumed to have an arbitrary Doppler spectrum with arbitrary Doppler bandwidth. Both optimum diversity reception and sub-optimum diversity reception are considered. Results available previously apply only to the case of first and second-order diversity. Our results are more general in that the order of diversity is arbitrary. Moreover, the bit error probability (BEP) result is obtained in an exact, closed-form expression which shows the behavior of the BEP as an explict function of the one-bit-interval fading correlation coefficient at the matched filter output, the mean signal-to-noise ratio per bit per branch and the order of diversity. A simple, more easily computable Chernoff bound to the BEP of the optimum diversity detector is also derived. © 2005 IEEE.
Sat, 01 Jan 2005 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/714152005-01-01T00:00:00Z
- Performance analysis of spectrum sensing for phase-modulated signal under MAP criterionhttps://scholarbank.nus.edu.sg/handle/10635/71391Title: Performance analysis of spectrum sensing for phase-modulated signal under MAP criterion
Authors: Fu, H.; Kam, P.-Y.
Abstract: This paper is concerned with detector design and performance analysis for spectrum sensing of phase-modulated signal in cognitive radio systems. Under the maximum a posteriori probability criterion, the optimal detector which outperforms the popular energy detector is derived, and its detection and false-alarm probabilities that describe the receiver operating characteristic (ROC) are analyzed. These probabilities are obtained as explicit, closed-form expressions, which show analytically ROC behavior as a function of various system parameters such as the signal-to-noise ratio and the number of data samples. The theoretical analysis and results are validated by computer simulations. © 2013 IEEE.
Tue, 01 Jan 2013 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/713912013-01-01T00:00:00Z
- Performance analysis of M-QAM in Rayleigh fading with channel estimationhttps://scholarbank.nus.edu.sg/handle/10635/71389Title: Performance analysis of M-QAM in Rayleigh fading with channel estimation
Authors: Fu, H.; Kam, P.Y.
Abstract: A new approach for analyzing the bit error probability (BEP) of square, multilevel, quadrature amplitude modulation (QAM) over a nonselective Rayleigh fading with imperfect channel estimation employing pilot-symbol-assisted- modulation is presented. The analytical approach here is much simpler and more powerful than that in the existing lietrature. The average BEP is obtained by calculating the BEP for each individual bit. The results derived are given in simple, closed-form expressions which show the behavior of the BEP as an explicit function of various system parameters, without requiring any numerical integration. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/713892006-01-01T00:00:00Z
- Linear estimation of the frequency and phase of a noisy sinusoidhttps://scholarbank.nus.edu.sg/handle/10635/70803Title: Linear estimation of the frequency and phase of a noisy sinusoid
Authors: Fu, H.; Kam, P.Y.
Abstract: We extend the study in [1] of estimating the frequency and carrier phase of a noisy sinusoid. We show that when the improved observation model is used, the linear regression estimator developed in [3] is suboptimal. Two generalized least-squares estimators, namely, the weighted least-squares estimator and the linear minimum variance estimator, are then formulated. To avoid phase unwrapping, we propose two new frequency estimators by using the differenced phase. The first is based on the ML estimator derived in [I]. The second is based on the approach in [4] but incorporates our improved observation model. © 2008 IEEE.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/708032008-01-01T00:00:00Z
- Sample-autocorrelation-function-based frequency estimation of a single sinusoid in AWGNhttps://scholarbank.nus.edu.sg/handle/10635/71701Title: Sample-autocorrelation-function-based frequency estimation of a single sinusoid in AWGN
Authors: Fu, H.; Kam, P.-Y.
Abstract: The problem of estimating the frequency of a single sinusoid observed in additive, white, Gaussian noise is addressed. An explicit, sample- autocorrelation-function-based, approximate maximum likelihood (ML) frequency estimator which does not require numerical search is derived. The structure of this estimator reveals that both the magnitude and the angle of the autocorrelation function should be utilized in estimation processing. Simulation results show that the estimator derived attains the Cramer-Rao lower bound at high signal-to-noise ratio, and has better performance than the planar filtered estimator developed in [22, 23] and the time-domain, approximate ML, received-signal-based estimator in [20, 21]. A new phase unwrapping algorithm is presented to faciliate an efficient, recursive implementation of the estimator. To have a better understanding on the sample-autocorrelation-function-based estimator, a geometric interpretation on the autocorrelation function is introduced. This interpretation allows us to propose a further simplified frequency estimator that resorts to the autocorrelation function angle increments to avoid phase unwrapping. By using the autocorrelation function expression, an alternative form to the frequency estimator of [20, 21] is derived. © 2012 IEEE.
Sun, 01 Jan 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/717012012-01-01T00:00:00Z
- Receiver design for linearly modulated signals with unknown carrier frequency and phase offsethttps://scholarbank.nus.edu.sg/handle/10635/71573Title: Receiver design for linearly modulated signals with unknown carrier frequency and phase offset
Authors: Fu, H.; Kam, P.Y.; Chui, C.C.
Abstract: This paper is concerned with receiver design for digital communications with linearly modulated signals over the additive, white Gaussian noise channel with unknown carrier frequency and phase offset The modulation techniques examined are phase shift keying with and without differential encoding and M-ary quadrature amplitude modulation. Two types of receiver structures are proposed, namely, the symbol-by-symbol receiver with pilot-symbol assisted-modulation and the simultaneous data detection and carrier frequency/phase offset estimation receiver. Both receivers incorporate the use of the maximum likelihood frequency/phase estimator of a single sinusoid in noise that we recently derived in [1] and [2] to estimate and compensate for the effects of the unknown carrier frequency and phase offset The error performance of the proposed receivers are examined via computer simulations. © 2008 IEEE.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/715732008-01-01T00:00:00Z
- Exponential-type bounds on the first-order Marcum Q-functionhttps://scholarbank.nus.edu.sg/handle/10635/83716Title: Exponential-type bounds on the first-order Marcum Q-function
Authors: Fu, H.; Kam, P.-Y.
Abstract: This paper presents new bounds on the Marcum Q-function Q 1(a,b). First, new, simple, arbitrarily tight, exponential lower bounds on the zeroth-order modifided Bessel function of the first kind I 0(x) and the Gaussian Q-function Q(x) are derived. Due to their elegant features, these new bounds are fundamental in their own rights. Then, when they are applied to the Marcum Q-function that is expressed as a function of I 0(x) and Q(x), various new exponential-type lower and upper bounds are developed. © 2011 IEEE.
Sat, 01 Jan 2011 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/837162011-01-01T00:00:00Z
- Lower bound on averages of the product of L Gaussian Q-functions over Nakagami-m Fadinghttps://scholarbank.nus.edu.sg/handle/10635/83911Title: Lower bound on averages of the product of L Gaussian Q-functions over Nakagami-m Fading
Authors: Fu, H.; Wu, M.-W.; Kam, P.-Y.
Abstract: This paper is concerned with performance analysis (in terms of bounds and approximations to the average symbol error probability (ASEP)) of a product and power of Gaussian Q - functions over Nakagami-m fading. The results are valid for arbitrary product/power order. This is done by first deriving a family of new, simple lower bounds on the Gaussian Q-function, which is obtained as a sum of products of an exponential function and cx where c is a constant. These lower bounds can be made arbitrarily tight as the number of summation terms increases, and thus, can be used to approximate the Gaussian Q-function accurately. Their applications to the evaluation of the ASEP are then presented. Some advantages of the results derived here over those given in the literature are briefly discussed. © 2013 IEEE.
Tue, 01 Jan 2013 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/839112013-01-01T00:00:00Z
- Simple error probability derivation for binary DPSK over fast Rician channels with diversityhttps://scholarbank.nus.edu.sg/handle/10635/57403Title: Simple error probability derivation for binary DPSK over fast Rician channels with diversity
Authors: Fu, H.; Kam, P.Y.
Abstract: Bit error probability (BEP) performance of binary differential phase shift keying (DPSK) with differential detection over the nonselective, fast Rician fading channels with combining diversity reception is analysed. The analytical approach that exists in previously published literature for computing the BEP relied on a special case of the derivation given by Proakis that was concerned with the probability that a general quadratic form in complex Gaussian random variables is less than zero. However, evaluating the various coefficients required in the derivation leads to a computationally intensive solution. A simple derivation is presented which leads to a new, alternative BEP expression.
Thu, 02 Feb 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/574032006-02-02T00:00:00Z
- Downlink scheduling with AMC and FCS in WCDMA networkshttps://scholarbank.nus.edu.sg/handle/10635/70014Title: Downlink scheduling with AMC and FCS in WCDMA networks
Authors: Fu, H.; Kim, D.I.
Abstract: This paper is concerned with the throughput and fairness analysis in a downlink WCDMA network with adaptive modulation and coding (AMC) and fast cell selection (FCS). The downlink scheduling schemes investigated include (i) the Round Robin scheme, (ii) the maximum carrier-to-interference ratio (C/I) scheme, and (iii) the proportional fair scheme. The channel model is assumed to include path loss, lognormal shadowing and fast Rayleigh fading. By using a form analogous to Shannon's channel capacity equation, a logrithmic relation between the instantaneous data rate and the C/I with AMC is first established. Using generalized Bernoulli trial, FCS is then examined in detail. Finally, the throughput and fairness expressions for the abovementioned downlink scheduling schemes with FCS are derived. © 2007 IEEE.
Mon, 01 Jan 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/700142007-01-01T00:00:00Z
- Effect of doppler shift on performance of binary DPSK over fast rician fading channels with diversity receptionhttps://scholarbank.nus.edu.sg/handle/10635/70070Title: Effect of doppler shift on performance of binary DPSK over fast rician fading channels with diversity reception
Authors: Fu, H.; Kam, P.Y.
Abstract: This paper is concerned with the effect of the Doppler shift on the bit error probability (BEP) performance of binary differential phase shift keying with differential detection over the nonselective, Rician fading channel with combining diversity reception. Space antenna diversity reception is assumed. The fading process is assumed to have an arbitrary Doppler spectrum with arbitrary Doppler bandwidth. Both optimal receiver where the Doppler shift has been perfectly compensated for and the suboptimum receiver where no estimation or compensation is made for the Doppler shift are studied. The BEP results derived are given by the exact, closed-form expressions which can show the BEP behavior as an explicit function of various system parameters. For the special case when the Doppler shift is equal to zero, the result provides a new, alternative BEP expression to those that exist in the literature.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/700702008-01-01T00:00:00Z
- Explicit, closed-form performance analysis in fading via new bound on Gaussian Q-functionhttps://scholarbank.nus.edu.sg/handle/10635/70258Title: Explicit, closed-form performance analysis in fading via new bound on Gaussian Q-function
Authors: Fu, H.; Wu, M.-W.; Kam, P.-Y.
Abstract: This paper aims at providing explicit, closed-form solutions to the error probability performance analysis of digital communications over fading channels. This is achieved by first deriving a family of new upper bounds on the Gaussian Q-function Q(x), which is given by a sum of products of the exponential function and c/x where c is a constant. The bounds obtained can be made arbitrarily tight as the number of summation terms increases, and thus, can be used to approximate Q(x) accurately. Their applications to the performance analysis over fading are then presented to highlight the significance of the bounds derived. Both short-term fading and combined short-term and long-term fading are considered. It is shown that the new bounds can lead to better performance than the popular exponential-type upper bounds. © 2013 IEEE.
Tue, 01 Jan 2013 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/702582013-01-01T00:00:00Z
- Exact phase noise model and its application to linear minimum variance estimation of frequency and phase of a noisy sinusoidhttps://scholarbank.nus.edu.sg/handle/10635/70235Title: Exact phase noise model and its application to linear minimum variance estimation of frequency and phase of a noisy sinusoid
Authors: Fu, H.; Kam, P.Y.
Abstract: The exact statistical models for the measurement phase noise in estimating the frequency and phase of a single sinusoid over the additive white Gaussian noise channel are derived. The a posteriori probability density function (PDF) and the a priori PDF of the phase noise derived are given by explicit, closed-form expressions that are valid for arbitrary signal-to-noise ratios. It is shown that as far as estimating the single sinusoid angle parameters is concerned, the phase ofthe received signal samples alone is a sufficient statistic, provided that the phase noise is modeled by the a posteriori PDF, which has a Tikhonov distribution. Furthermore, we illustrate that the results derived can yield various phase noise models as special cases, and the underlying physical insights and interconnections that exist among these models are revealed. The application of these models to the design of linear minimum variance estimator is presented, and their estimation performances are compared through computer simulations © 2008 IEEE.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/702352008-01-01T00:00:00Z
- Improved weighted phase averager for frequency estimation of single sinusoid in noisehttps://scholarbank.nus.edu.sg/handle/10635/56283Title: Improved weighted phase averager for frequency estimation of single sinusoid in noise
Authors: Fu, H.; Kam, P.Y.
Abstract: Proposed is an improved weighted-phase-averager frequency estimator which is obtained following the approach of Kay (see Reference [1]), but incorporates the present authors' new phase noise observation model developed (see Reference [2]). Their mean square estimation error performances are compared using computer simulations, the results of which show that the estimator based on the new model performs moderately better, especially at low signal-to-noise ratios. Moreover, since the phase noise in the new model has a time-varying variance, it can intelligently indentify those observed instantaneous signal phase samples with larger errors. By dropping these samples, it is shown by simulation that the improved weighted phase averager can lead to further performance improvement for low SNR. © The Institution of Engineering and Technology 2008.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/562832008-01-01T00:00:00Z
- MAP/ML estimation of the frequency and phase of a single sinusoid in noisehttps://scholarbank.nus.edu.sg/handle/10635/56582Title: MAP/ML estimation of the frequency and phase of a single sinusoid in noise
Authors: Fu, H.; Kam, P.Y.
Abstract: The problem of estimating the frequency and carrier phase of a single sinusoid observed in additive, white, Gaussian noise is addressed. Much of the work in the literature considers maximum likelihood (ML) estimation. However, the ML estimator given by the location of the peak of a periodogram in the frequency domain shown in D.C. Rife and R. R. Boorstyn, "Single-tone parameter estimation from discrete-time observations," IEEE Transactions on Information Theory, vol. IT-20, pp. 591-598, Sep. 1974, has a very high computational complexity. This paper derives the explicit structure of the ML estimator for data processing in the time domain, assuming only reasonably high signal-to-noise ratio (SNR). The result of this approximate ML estimator shows that both the phase and the magnitude of the noisy signal samples are utilized in the estimator, and the phase data alone as assumed in S. A. Tretter, "Estimating the frequency of a noisy sinusoid by linear regression," IEEE Transactions on Information Theory, vol. IT-31, pp. 832-835, Nov. 1985 and S. Kay, "A fast and accurate single frequency estimator," IEEE Transactions on Acoustics, Speech, and Signal Processing, vol. 39, pp. 1203-1205, May 1991, is not a sufficient statistic. The sample-by-sample iterative processing nature of the estimator enables us to propose a novel, recursive phase-unwrapping algorithm that allows the estimator to be implemented efficiently. To facilitate the performance analysis, a new, linearized observation model for the instantaneous signal phase that is more accurate than that of S. A. Tretter, "Estimating the frequency of a noisy sinusoid by linear regression," IEEE Transactions on Information Theory, vol. IT-31, pp. 832-835, Nov. 1985 and of S. Kay, "A fast and accurate single frequency estimator," vol. 39, pp. 1203-1205, May 1991, is proposed. This new model explains physically why the phase data are weighted by the magnitude information in the ML estimator. Moreover, by incorporating a priori knowledge via the a priori probability density function of the unknown frequency and the carrier phase, the explicit structure of the approximate maximum a posteriori probability (MAP) estimator is derived, and the Bayesian CramerRao lower bound (BCRLB) on the mean-square error (mse) is obtained. Our analysis shows that the mse performance of the MAP estimator can approach the BCRLB very closely. © 2007 IEEE.
Thu, 01 Mar 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/565822007-03-01T00:00:00Z
- Analysis of throughput and fairness of WCDMA networks with downlink schedulinghttps://scholarbank.nus.edu.sg/handle/10635/69409Title: Analysis of throughput and fairness of WCDMA networks with downlink scheduling
Authors: Fu, H.; Kim, D.I.
Abstract: In this paper we develop a theoretical framework which enables us to analyze the throughput and fairness performance of various downlink scheduling schemes in WCDMA networks. For theoretical analysis, the following scheduling schemes are considered: (1) the Round Robin scheme, (ii) the maximum carrier-to-interference ratio (C/I) scheme and (iii) the proportional fair scheme. By deriving a close approximation to the probability density function of C/I, new, exact throughput and fairness expressions are formulated for the above scheduling schemes, by which a rigorous quantitative comparison among them can be performed. The results verify that throughput and fairness performance of each scheduling scheme depends largely on mobile users' location in the active cell. In general, the Round Robin scheme has the worst throughput performance among them, while the proportional fair scheme provides a better trade-off between throughput and fairness. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/694092006-01-01T00:00:00Z
- Phase-based, time-domain estimation of the frequency and phase of a single sinusoid in AWGN-the role and applications of the additive observation phase noise modelhttps://scholarbank.nus.edu.sg/handle/10635/57049Title: Phase-based, time-domain estimation of the frequency and phase of a single sinusoid in AWGN-the role and applications of the additive observation phase noise model
Authors: Fu, H.; Kam, P.-Y.
Abstract: This paper presents the theoretical foundation for time-domain, phase-based estimation of the frequency and phase of a single sinusoid in additive white Gaussian noise (AWGN), analogous to the theoretical foundation provided by Rife and Boorstyn for frequency-domain, Fourier-transform-based estimation. It is shown from the maximum a posteriori probability (MAP) and the maximum likelihood (ML) estimation principles that with the additive observation phase noise (AOPN), due to the AWGN, being described by its a posteriori distribution conditioned on the received signal magnitude, the received signal phase is a sufficient statistic for estimating the single-sinusoid angle parameters. Using a geometric approach, the exact statistical model for the AOPN is derived, where the a posteriori probability density function (pdf) and the corresponding a priori pdf are given by explicit, closed-form expressions that are valid for arbitrary signal-to-noise ratios (SNRs). The a posteriori pdf is Tikhonov, and is of particular interest as it establishes the AOPN model for phase-based frequency/phase MAP/ML estimation in the time domain. It is further illustrated that the results derived can yield various AOPN models as special cases, and the underlying physical insights and interconnections that exist among these models are revealed. It is shown that the model derived by Tretter is an ultimate specialization in the high SNR limit of the AOPN models developed here. For high SNR, the a posteriori Tikhonov pdf can be accurately approximated by a Gaussian distribution, which leads to the best linearized AOPN model. The applications of these AOPN models to the design of linear estimators, including the linear minimum mean square error (LMMSE) estimator, the linear minimum variance estimator, and the LMMSE implementation of the weighted phase averager are presented, and their estimation performances are compared through computer simulations, with the Cramer-Rao lower bound (CRLB) and the Bayesian CRLB as the benchmark. To facilitate estimator design, the a priori statistical models of the frequency and phase are proposed from the information-theoretic perspective, and an improved phase unwrapping algorithm over that given by Fu and Kam is presented. It is shown that by incorporating all the information available in the AOPN, the estimation accuracy can be much improved. © 1963-2012 IEEE.
Tue, 01 Jan 2013 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/570492013-01-01T00:00:00Z
- Improved, approximate, time-domain ML estimators of chirp signal parameters and their performance analysishttps://scholarbank.nus.edu.sg/handle/10635/56285Title: Improved, approximate, time-domain ML estimators of chirp signal parameters and their performance analysis
Authors: Li, Y.; Fu, H.; Kam, P.Y.
Abstract: We derive an improved, approximate, maximum likelihood (ML) estimator for the parameters of a single-component chirp signal in the time domain, which has much lower computational complexity than that of the traditional estimators in the frequency domain. We term it the zero-order amplitude weighted phase-based estimator (AWPE). It is a weighted linear combination of the phases of the received signal samples, where the weights are determined by the amplitudes of the received signals. It achieves better performance than the only existing time-domain estimator in the literature that only exploits the phase information. A phase unwrapping (PU) algorithm is needed to recover the phase information correctly from the received signal samples. Several PU algorithms are compared and analyzed. A new, robust PU algorithm based on the first-order phase differences of the consecutive received signal samples is proposed. This new unwrapping algorithm has smaller PU failure probability than that based directly on the phases of the received signal samples. The need for PU can even be removed by using the second-order phase differences of the consecutive received signal samples. Two additional structures for the ML-based AWPE using the phase differences are derived starting from using the zero-order AWPE obtained. The first is based on the first-order phase differences and the second on the second-order phase differences. When the PU algorithm works perfectly, i.e., no phase unwrapping failure occurs, the estimators based on phase differences do not perform as well as the original one based on absolute phase information due to the increased noise variance. This is also applicable when the chirp parameters take on very small values. However, when no knowledge of the ranges of the chirp parameters is available, and the possible PU failures are taken into account, the estimators based on the phase differences could perform better. Performance analysis of the estimators is given based on an improved phase noise model. It is easy to verify that the estimates obtained are unbiased. The Cramér-Rao lower bound (CRLB) on the mean-square error (MSE) is derived. The MSE performance of the estimators approaches the CRLB at high signal-to-noise ratios. The variance performance of the estimators based on phase differences is analyzed, whose validity is demonstrated by simulation results. © 2009 IEEE.
Thu, 01 Jan 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/562852009-01-01T00:00:00Z
- Exact phase noise model for single-tone frequency estimation in noisehttps://scholarbank.nus.edu.sg/handle/10635/55942Title: Exact phase noise model for single-tone frequency estimation in noise
Authors: Fu, H.; Kam, P.Y.
Abstract: The a posteriori and the a priori statistical models for the measurement phase noise (MPN) in estimating the frequency and phase of a single tone over the additive white Gaussian noise channel are derived. Both models are described by exact, explicit, closed-form probability density functions (pdf's) that are valid for arbitrary signal-to-noise ratio. It is shown that as far as estimating the single-tone angle parameters is concerned, the received signal phase is a sufficient statistic, provided that the MPN is modelled by the a posteriori pdf. It is illustrated that the results derived can yield various MPN models as special cases, and the underlying physical insights and interconnections that exist among these models are revealed. The application of these models to the design of a linear minimum variance estimator is presented. © 2008 The Institution of Engineering and Technology.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/559422008-01-01T00:00:00Z
- A simple bit error probability analysis for square QAM in rayleigh fading with channel estimationhttps://scholarbank.nus.edu.sg/handle/10635/54804Title: A simple bit error probability analysis for square QAM in rayleigh fading with channel estimation
Authors: Fu, H.; Kam, P.Y.
Abstract: A new approach is presented for analyzing the bit error probability (BEP) of square, multilevel, quadrature amplitude modulation over a nonselective Rayleigh fading channel, with imperfect channel estimation employing pilot-symbolassisted- modulation. It is much simpler and more powerful than those in the literature, and the average BEP is obtained by calculating the BEP for each individual bit. The results are given in simple, exact, closed-form expressions that do not require any numerical integration. These expressions show explicitly the behavior of the BEP as a function of various system parameters. Three channel estimation schemes are investigated. It is shown that existing channel estimation schemes using sinc interpolation and Gaussian interpolation can be improved. © 2009 IEEE.
Thu, 01 Jan 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/548042009-01-01T00:00:00Z
- Technique for analysing error probability of π/2-wedge-shaped decision regionhttps://scholarbank.nus.edu.sg/handle/10635/57598Title: Technique for analysing error probability of π/2-wedge-shaped decision region
Authors: Fu, H.; Li, K.H.; Kam, P.Y.
Abstract: A new approach for analysing the error probability of a signal constellation that involves a π/2-radian, wedge-shaped decision in additive white Gaussian noise is presented. The result is obtained in exact closed-form in terms of the Q-function. Applied to 8-QAM, this approach gives an exact closed-form expression for the symbol error probability. © IEE 2005.
Thu, 03 Mar 2005 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/575982005-03-03T00:00:00Z
- Estimating the frequency and phase of a noisy sinusoid by Kalman filterhttps://scholarbank.nus.edu.sg/handle/10635/51158Title: Estimating the frequency and phase of a noisy sinusoid by Kalman filter
Authors: Kam, P.Y.; Fu, H.
Abstract: A linear, two-dimensional state-space model involving the instantaneous signal frequency and carrier phase is formulated. This enables Kalman filtering to be used for estimating the frequency and phase. Two Kalman filters are presented here, one based on the old observation model of Tretter [3], and the other based on our newly proposed model in [1]. The Kalman filter for the old observation model requires knowledge of the signal amplitude and the noise variance, while for the new observation model, only knowledge of the noise variance is required. Their mean square estimation error performances are compared using simulations, and it is shown that the filter based on the new observation model performs better, especially at low signal-to-noise ratio. Kalman filtering also allows the incorporation of prior knowledge of the interval of distribution of the frequency to improve the estimation performance. ©2007 IEEE.
Mon, 01 Jan 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/511582007-01-01T00:00:00Z
- Kalman estimation of single-tone parameters and performance comparison with MAP estimatorhttps://scholarbank.nus.edu.sg/handle/10635/56441Title: Kalman estimation of single-tone parameters and performance comparison with MAP estimator
Authors: Fu, H.; Kam, P.Y.
Abstract: By incorporating a priori knowledge via the a priori probability density function of the frequency and phase, the Kalman estimator for linear, minimum mean-square error estimation of these single-tone parameters in additive, white, Gaussian noise is presented. First, a linear, two-dimensional state-space model for the frequency and phase of a sinusoid is formulated. Then, two Kalman filters are proposed, one based on Tretter's phase noise model [S. A. Tretter, ldquoEstimating the Frequency of a Noisy Sinusoid by Linear Regression,rdquo IEEE Transactions on Information Theory, vol. IT-31, no. 6, pp. 832-835, Nov. 1985], and the other based on our newly proposed model in [H. Fu and P. Y. Kam, ldquoMAP/ML Estimation of the Frequency and Phase of a Single Sinusoid in Noise,rdquo IEEE Transactions on Signal Processing, vol. 55, no. 3, Mar. 2007]. Finally, their mean-square error performances are compared with each other and with that of the maximum a posteriori probability (MAP) estimator, using computer simulations. The results show that the MAP estimator performs best and the Kalman filter based on the improved phase noise model has better performance than that based on Tretter's model, especially at low signal-to-noise ratio. © 2008 IEEE.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/564412008-01-01T00:00:00Z
- Analysis of throughput and fairness with downlink scheduling in WCDMA networkshttps://scholarbank.nus.edu.sg/handle/10635/55099Title: Analysis of throughput and fairness with downlink scheduling in WCDMA networks
Authors: Fu, H.; Kim, D.I.
Abstract: This paper is concerned with the throughput and fairness analysis in a downlink WCDMA network. The channel model is assumed to include path loss, lognormal shadowing and fast Rayleigh fading. The scheduling schemes investigated are (i) the Round Robin scheme, (ii) the maximum carrier-to-interference ratio (C/I) scheme, (iii) the proportional fair scheme, (iv) the maximum instantaneous signal scheme, and (v) the fading-based signal power scheme. By using an approximation of the probability density function of C/I, throughput and fairness expressions are derived, and a performance comparison among the five scheduling schemes is given. The results indicate that throughput and fairness performance of each scheduling scheme depends on mobile users' location. In general, the Round Robin scheme has the worst throughput performance as compared to the other four schemes. The proportional fair scheme and the fading-based signal power scheme can provide relatively better tradeoffs between the throughput and the fairness. The findings presented here are not only of fundamental theoretical value, but are also of practical interest to the designers of third-generation mobile communication systems based on WCDMA technology. © 2006 IEEE.
Tue, 01 Aug 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/550992006-08-01T00:00:00Z
- Weighted phase averager for frequency estimation of a noisy single sinusoid: Application of the observation phase noise modelhttps://scholarbank.nus.edu.sg/handle/10635/72190Title: Weighted phase averager for frequency estimation of a noisy single sinusoid: Application of the observation phase noise model
Authors: Fu, H.; Kam, P.Y.
Abstract: The exact statistical models for the observation phase noise (OPN) and their approximations in time-domain, phase-based estimation of the frequency and phase of a noisy single sinusoid are summarized, and the underlying physical interconnections are highlighted. The application of the various OPN models to the design of the weighted phase averager (WPA) estimator is developed. Simulation results show that using the time-varying OPN variance information which can intelligently indentify those phase samples with large errors, the performance of the WPA estimators can be improved, especially for low SNR. ©2009 IEEE.
Thu, 01 Jan 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/721902009-01-01T00:00:00Z
- Performance comparison of selection combining schemes for binary DPSK on nonselective Rayleigh-fading channels with interferencehttps://scholarbank.nus.edu.sg/handle/10635/57024Title: Performance comparison of selection combining schemes for binary DPSK on nonselective Rayleigh-fading channels with interference
Authors: Fu, H.; Kam, P.Y.
Abstract: This paper is concerned with the error performance analysis of binary differential phase shift keying (DPSK) with differential detection over the nonselective Rayleigh-fading channel with selection diversity reception and with an additive, correlated, Gaussian interference process in each diversity channel. The fading process is assumed to have an arbitrary Doppler spectrum with arbitrary Doppler bandwidth. The selection schemes investigated are: 1) the selection combining (SC) scheme based on signal-to-noise power ratio (SNR); 2) the SC scheme based on signal-plus-noise (S + N) ; and 3) the SC scheme based on maximum output (MO). New, exact, closed-form bit-error probability (BEP) expressions are derived, and a performance comparison among the three SC schemes and combining diversity reception is given. The results obtained reduce to previously known results when the correlated interference process is absent, and when the fading process does not fluctuate over the duration of several symbol intervals. The results indicate that the performance of each scheme depends on the tradeoff between the number of diversity branches, the SNR, the interference level, and the correlation of the interference process. However, the SC-(S + N) scheme generally performs worse than the SC-SNR scheme, the SC-MO scheme and combining diversity reception scheme. The findings presented here are not only of fundamental theoretical value, but are also of practical interest to the designers of future mobile communication systems. © 2005 IEEE.
Sat, 01 Jan 2005 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/570242005-01-01T00:00:00Z
- Performance of optimum and suboptimum combining diversity reception for binary and quadrature DPSK over independent, nonidentical rayleigh fading channelshttps://scholarbank.nus.edu.sg/handle/10635/57036Title: Performance of optimum and suboptimum combining diversity reception for binary and quadrature DPSK over independent, nonidentical rayleigh fading channels
Authors: Fu, H.; Kam, P.Y.
Abstract: This paper is concerned with the error-performance analysis of binary and quadrature differential phase-shift keying with differential detection over the nonselective, Rayleigh fading channel with combining diversity reception. The diversity channels are independent, but have nonidentical statistics. The fading process in each channel is assumed to have an arbitrary Doppler spectrum with arbitrary Doppler bandwidth. Both optimum diversity reception and suboptimum diversity reception are considered. Results available previously apply only to the case of second-order diversity, and require numerical integration for their actual evaluation. Our results are more general, in that the order of diversity is arbitrary. Moreover, the bit-error probability (BEP) result is obtained in an exact, closed-form expression which shows the behavior of the BEP as an explict function of the one-symbol-interval fading correlation coefficient at the matched-filter output, the mean received signal-to-noise ratio per symbol per channel, and the order of diversity. © 2007 IEEE.
Tue, 01 May 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/570362007-05-01T00:00:00Z
- New representations and bounds for the generalized marcum Q-function via a geometric approach, and an applicationhttps://scholarbank.nus.edu.sg/handle/10635/82754Title: New representations and bounds for the generalized marcum Q-function via a geometric approach, and an application
Authors: Li, R.; Kam, P.Y.; Fu, H.
Abstract: The generalized Marcum Q-function of order m, Qm(a, b), is interpreted geometrically as the probability of a 2m-dimensional, real, Gaussian random vector z2m, whose mean vector has a Frobenius norm of a, lying outside of a hyperball B2m o,b of 2m dimensions, with radius b, and centered at the origin O. Based on this new geometric view, some new representations and closed-form bounds are derived for Qm(a, b). For the case that m is an odd multiple of 0.5, a new closed-form representation is derived, which involves only simple exponential and erfc functions. For the case that m is an integer, a pair of new, finite-integral representations for Q m(a, b) is derived. Some generic exponential bounds and erfc bounds are also derived by computing the probability of z2m lying outside of various bounding geometrical shapes whose surfaces tightly enclose, or are tightly enclosed by the surface of B2m o,b. These bounding shapes consist of an arbitrarily large number of parts. As their closeness of fit with B2m o,b improves, our generic bounds approach the exact value of Qm(a, b). The function Qm(a, b) is proved to be an increasing function of its order when 2m is a positive integer. Thus, Qm+0.5(a, b) and Qm-0.5(a, b) can be used as tight upper and lower bounds, respectively, on Qm(a, b). Their average is a good approximation to Qm(a, b). An application of our new representations and bounds is also given. © 2010 IEEE.
Fri, 01 Jan 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/827542010-01-01T00:00:00Z
- Differential diversity reception of MDPSK over independent Rayleigh channels with nonidentical branch statistics and asymmetric fading spectrumhttps://scholarbank.nus.edu.sg/handle/10635/51148Title: Differential diversity reception of MDPSK over independent Rayleigh channels with nonidentical branch statistics and asymmetric fading spectrum
Authors: Fu, H.; Kam, P.Y.
Abstract: This paper is concerned with optimum diversity receiver structure and its performance analysis of differential phase shift keying (DPSK) with differential detection over nonselective, independent, nonidentically distributed, Rayleigh fading channels. The fading process in each branch is assumed to have an arbitrary Doppler spectrum with arbitrary Doppler bandwidth, but to have distinct, asymmetric fading power spectral density characteristic. Using 8-DPSK as an example, the average bit error probability (BEP) of the optimum diversity receiver is obtained by calculating the BEP for each of the three individual bits. The BEP results derived are given in exact, explicit, closed-form expressions which show clearly the behavior of the performance as a function of various system parameters. ©2007 IEEE.
Mon, 01 Jan 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/511482007-01-01T00:00:00Z
- Scheduling performance in downlink WCDMA networks with AMC and fast cell selectionhttps://scholarbank.nus.edu.sg/handle/10635/71714Title: Scheduling performance in downlink WCDMA networks with AMC and fast cell selection
Authors: Fu, H.; Kim, D.I.
Abstract: This paper is concerned with the analysis of scheduling performance in downlink WCI)MA networks that employ adaptive modulation and coding (AMC) and fast cell selection (FCS). The scheduling schemes investigated include (i) the Round Robin (RR) scheme, (ii) the maximum carrier-to-interference ratio (C/I) scheme, (iii) the simplified proportional fair (PF) scheme, and (iv) the conventional PF scheme. The channel model includes large-scale signal attenuation and small-scale fading. By using a form analogous to Shannon's channel capacity formula, a logarithmic relationship between the instantaneous data rate and the C/I with AMC is first established. Using the so-called Poisson scheme in which the probabilities of the occurrence of the events in Bernoulli trials depend on the trial index, FCS implementation is then examined in detail. Finally, a complete set of analytical expressions on the average system throughput, the peak data rate and the fairness for the abovementioned scheduling schemes are derived. © 2008 IEEE.
Tue, 01 Jul 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/717142008-07-01T00:00:00Z