ScholarBank@NUShttps://scholarbank.nus.edu.sgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Wed, 19 Jun 2019 13:39:06 GMT2019-06-19T13:39:06Z502481- Cooperative space-time block coding with amplify-and-forward strategy: Exact bit error probability and adaptive forwarding schemeshttps://scholarbank.nus.edu.sg/handle/10635/55446Title: Cooperative space-time block coding with amplify-and-forward strategy: Exact bit error probability and adaptive forwarding schemes
Authors: He, J.; Kam, P.Y.
Abstract: Cooperative space-time block coding (STBC) is a distributed way to exploit spatial diversity. Because of its simplicity, the amplify-and-forward (AF) strategy is often used at relays. However, the exact performance of this strategy is not available in the existing works. Therefore, in the first part of this paper, we analyze the performance of cooperative STBC with the AF strategy. Exact bit error probabilities (BEP) are derived in closed form for three existing protocols. Since the AF strategy simply forwards the signals at the relays, the noise at the relay is also forwarded to the destination, and it degrades the received signals from both the relay and the source, due to the receiver structure of STBC. In the second part of this paper, we examine the effect of the forwarded noise and propose a condition under which the relay should stop forwarding the signals. Based on this condition, adaptive forwarding schemes for cooperative STBC are proposed. The performances of these schemes are studied and the exact BEP's are also obtained in closed form. Finally, the energy efficiencies of these adaptive schemes are discussed. © 2008 Elsevier B.V. All rights reserved.
Mon, 01 Sep 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/554462008-09-01T00:00:00Z
- Improved sequence estimator for MPSK with carrier phase noisehttps://scholarbank.nus.edu.sg/handle/10635/80580Title: Improved sequence estimator for MPSK with carrier phase noise
Authors: Kam, P.Y.; Cheong, F.H.K.
Abstract: An improved version of the sequence estimator for MPSK previously developed is presented. It is shown to have better bit error probability performance in the presence of carrier phase noise. This improvement comes from incorporating more channel memory into the trellis on which the estimator operates.
Thu, 04 Jul 1996 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/805801996-07-04T00:00:00Z
- Optimal detection of digital data over the nonselective Rayleigh fading channel with diversity receptionhttps://scholarbank.nus.edu.sg/handle/10635/80906Title: Optimal detection of digital data over the nonselective Rayleigh fading channel with diversity reception
Authors: Kam, Pooi Yuen
Abstract: Based on the criterion of minimum symbol error probability, an analysis is made of symbol-by-symbol detection of a sequence of digital data transmitted using linear suppressed-carrier modulation over L independent diversity channels with AWGN (additive white Gaussian noise) and slow nonselective Rayleigh fading. The optimal receiver is derived, but is found to be difficult to implement in practice because of its exponential growth in complexity as a function of sequence length. Suboptimal decision-feedback approximations are then suggested which are linear and readily implementable and can be integrated as generalized differentially coherent receivers. The exact bit error probabilities of these suboptimal receivers are obtained. Tight upper bounds on these error probabilities are also obtained which show simply how they behave as a function of signal-to-noise ratio and order of diversity. A main conclusion of this work is that optimal data detection on a fading channel should be performed using MMSE (minimum mean squared error) estimates of the quadrature amplitudes of the channel fading processes as a coherent reference. Conventional receivers employing carrier loops to provide the coherent reference are not optimal and lead to more complicated receiver structures.
Fri, 01 Feb 1991 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/809061991-02-01T00:00:00Z
- Optimum symbol-by-symbol detection of uncoded digital data over the Gaussian channel with unknown carrier phasehttps://scholarbank.nus.edu.sg/handle/10635/80920Title: Optimum symbol-by-symbol detection of uncoded digital data over the Gaussian channel with unknown carrier phase
Authors: Kam, Pooi Yuen; Ng, Seng Siew; Ng, Tok Soon
Abstract: A theory of optimum receiver design for symbol-by-symbol detection of an uncoded digital data sequence received over the Gaussian channel with unknown carrier phase is presented. Linear suppressed-carrier modulation is assumed. The work here aims at laying a conceptual foundation for optimum symbol-by-symbol detection, and rectifies existing approaches to the problem. The optimum receiver structure is obtained explicitly for an arbitrary carrier phase model, but its computational requirements are too heavy in general for any practical implementation. In one important special case, namely, the case in which the carrier phase can be treated as a constant over some K+1 symbol intervals, the optimum receiver can be approximated by a readily implementable decision-feedback structure at high SNR. Simulated error performance results are presented for this latter receiver for PSK modulations with various carrier phase models. Since a decision-feedback receiver can encounter a `runaway,' a variation of this receiver is developed which uses feedforward of tentative decisions concerning future symbols. This modified receiver does not have any `runaway' problem, and has been shown to yield good error performance via simulations.
Mon, 01 Aug 1994 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/809201994-08-01T00:00:00Z
- A new geometric view of the first-order marcum Q-function and some simple tight erfc-boundshttps://scholarbank.nus.edu.sg/handle/10635/83382Title: A new geometric view of the first-order marcum Q-function and some simple tight erfc-bounds
Authors: Kam, P.Y.; Li, R.
Abstract: A geometric interpretation of the first-order Marcum Q-function, Q(a,b), is introduced as the probability that a complex, Gaussian random variable with real, nonzero mean a, takes on values outside of a circular region Cb of radius b centered at the origin. This interpretation engenders a fruitful approach for deriving new representations and tight, upper/lower erfc-bounds on Q(a,b). The new representations involve finite-range integrals that facilitate analytical and numerical computations, and are simpler than similar ones in the literature. The new, simple erfc-bounds are easily obtained by using simple geometrical shapes that tightly enclose, or are tightly enclosed by the circle Cb. They involve only a few terms of erfc and exponential functions, and are close to, or even tighter than the existing bounds that involve the modified Bessel function. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/833822006-01-01T00:00:00Z
- Bit error probability for orthogonal space-time block codes with differential detectionhttps://scholarbank.nus.edu.sg/handle/10635/83518Title: Bit error probability for orthogonal space-time block codes with differential detection
Authors: Soh, T.P.; Kam, P.Y.; Ng, C.S.
Abstract: Explicit closed-form expressions of the bit error probabilities are obtained for space-time block codes based on generalized orthogonal designs with differential encoding and differential detection utilizing 2b-ary phase shift keying mapping. The frequency non-selective, block-wise constant Rayleigh fading channel is considered here. The results are applicable to any arbitrary Doppler spectrum and any number of transmit and receive antennas, where the number of transmit antennas is dictated by the available coding schemes. © 2005 IEEE.
Sat, 01 Jan 2005 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/835182005-01-01T00:00:00Z
- Bit error probability for orthogonal space time block codes with differential detectionhttps://scholarbank.nus.edu.sg/handle/10635/83517Title: Bit error probability for orthogonal space time block codes with differential detection
Authors: Soh, T.P.; Kam, P.Y.; Ng, C.S.
Abstract: The bit error probability (BEP) of space time block codes (STBC) based on Alamouti's scheme with differential encoding and decoding and ultilising 2 b-ary phase shift keying (2 b-PSK) modulation is studied and close form analytical results are obtained. The channel model is that of a frequency non-selective and slow Rayleigh fading channel. While all existing analyses assume no fading fluctuations, these are considered in our analysis here. For the case in which the fading process remains constant within any code block interval but which fluctuates from one code block interval to the next, exact closed-form expressions for the BEP of binary and quadrupture PSK are derived. An approximate result is obtained for 8PSK. For the case in which the fading process fluctuates from one symbol interval to the next, but which remain constant within the symbol interval, upper and lower bounds are obtained for the BEP and a simple and yet accurate approximation to the BEP is developed. The analysis is applicable to any number of receive antennas.
Thu, 01 Jan 2004 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/835172004-01-01T00:00:00Z
- Generalized quadratic receivers for orthogonal signals over the Gaussian channel with unknown phase/fadinghttps://scholarbank.nus.edu.sg/handle/10635/80498Title: Generalized quadratic receivers for orthogonal signals over the Gaussian channel with unknown phase/fading
Authors: Yuen Kam, Pooi; Sinha, Pranesh; Some, Yew K.
Abstract: The orthogonal signal structure has been shown to be the superposition of an antipodal signal set and an unmodulated (pilot tone) component which can be used for channel measurement. Starting from this point of view, the quadratic receiver for orthogonal signals over the Gaussian channel with unknown phase/fading has been shown to be equivalent to a detector-estimator receiver. The estimator makes an optimum estimate of the unknown complex channel gain based on the channel measurement provided by the unmodulated component of the received signal. This channel estimate then forms a (partially) coherent reference for the detector in detecting the data carried by the antipodal signaling component of the received signal. This paper exploits this detector-estimator structure of the quadratic receiver, and generalizes it to a receiver in which the estimator makes an estimate of the channel gain in each signaling interval based on the totality of signals received over all the signaling intervals or a subset of these intervals. The generalized quadratic receiver is just as simple to implement as the conventional quadratic receiver, and theoretical and simulation results show that it can achieve substantial performance gains over the conventional receiver. A theory is presented to show that the generalized quadratic receiver is an implementable approximation to the optimum symbol-by-symbol receiver for uncoded orthogonal signals over the Gaussian channel with unknown phase/fading. The theory shows that the structure provides a unified and systematic approach to the design of coherent symbol-by-symbol receivers, and shows that the conventional carrier-loop-type receivers are ad hoc.
Thu, 01 Jun 1995 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/804981995-06-01T00:00:00Z
- FSK detection using frequency estimatorhttps://scholarbank.nus.edu.sg/handle/10635/80464Title: FSK detection using frequency estimator
Authors: Kam, Pooi Yuen
Abstract: A receiver for FSK in noise is proposed based on the use of an unbiased minimum-variance frequency estimator. It allows a complete digital implementation, and is robust in that knowledge of the frequency deviation and carrier phase is not required. The BER of the receiver is obtained using computer simulations.
Sun, 01 Jan 1995 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/804641995-01-01T00:00:00Z
- Further results on the bit error probabilities of MDPSK over the nonselective Rayleigh fading channel with diversity receptionhttps://scholarbank.nus.edu.sg/handle/10635/80469Title: Further results on the bit error probabilities of MDPSK over the nonselective Rayleigh fading channel with diversity reception
Authors: Kam, Pooi Yuen; Soh, Thian Ping; Ng, Chun Sum
Abstract: This paper presents a fundamental approach for deriving the bit error probability of BDPSK and QDPSK over the nonselective Rayleigh fading channel for a receiver with an arbitrary IF filter, and for a fading process with an arbitrary Doppler spectrum with arbitrary Doppler bandwidth. The results generalize those published earlier which were restricted to matched filter reception and to a fading process with a small Doppler bandwidth compared to the symbol rate. This allows the error probability to be studied in the presence of varying degrees of ISI due to bandlimitation of the received signal by the IF filter, and in the presence of fading fluctuations of various rates. The analytical approach here is simple, and yet powerful in that it can handle the case of diversity reception. This is a great advantage over the alternative approach of using the distribution of the differential phase of the received signal over a symbol interval. The bit error probability results apply to both conventional BDPSK and QDPSK, as well as π/2-2DPSK and π/4-4DPSK, and allow the irreducible bit error probability as well as the SNR at which this irreducible value sets in to be studied as a function of Doppler bandwidth and IF filter bandwidth. The computed results presented here are applicable to the design of digital cellular mobile communication systems.
Wed, 01 Nov 1995 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/804691995-11-01T00:00:00Z
- A low-complexity carrier phase and frequency offset estimator with adaptive filter length for coherent receivershttps://scholarbank.nus.edu.sg/handle/10635/83364Title: A low-complexity carrier phase and frequency offset estimator with adaptive filter length for coherent receivers
Authors: Meiyappan, A.; Kam, P.-Y.; Kim, H.
Abstract: We present a low-complexity joint carrier phase and frequency offset estimator, with adaptive sample averaging length according to the modulation format, signal-to-noise ratio, and laser linewidth. No preset parameters are required. It also achieves complete frequency estimation range.
Tue, 01 Jan 2013 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/833642013-01-01T00:00:00Z
- On the performance of space-time block coded systems with channel estimationhttps://scholarbank.nus.edu.sg/handle/10635/71244Title: On the performance of space-time block coded systems with channel estimation
Authors: Shan, C.; Kam, P.Y.; Nallanathan, A.
Abstract: Most previous analytical works on the performance of space-time block coded systems are based on perfect channel estimation at the receiver, which is impossible in practice. In this paper, we present a maximum-likelihood (ML) receiver jointly with channel estimation for a space-time orthogonal block coded system. Based on this receiver structure, we derive exact, closed-form expressions as well as tight upper bounds for the bit error rate (BER) with MPSK modulation over the slow, nonselective, Rayleigh fading channel. Our BER expressions show directly the dependence of the BER on the mean square error of the channel estimator. Simulation results using a Wiener filter as the channel estimator for Jakes' Rayleigh fading model are obtained to demonstrate the accuracy of the analysis. © 2004 IEEE.
Thu, 01 Jan 2004 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/712442004-01-01T00:00:00Z
- On the performance of orthogonal space-time block codes over independent, nonidentical Rayleigh/Ricean fading channelshttps://scholarbank.nus.edu.sg/handle/10635/71243Title: On the performance of orthogonal space-time block codes over independent, nonidentical Rayleigh/Ricean fading channels
Authors: He, J.; Kam, P.Y.
Abstract: We consider the bit error performance or orthogonal space-time block codes (STBC) over independent, non-identically distributed, Rayleigh/Ricean, block fading channels with perfect channel state information. With symbol-by-symbol detection, we derive the expressions for the exact bit error probability (BEP) in both Rayleigh and Ricean fading channels. The results are applicable to any number of transmit and receive antennas for which orthogonal STBC's are defined. A simple but insightful upper bound on the BEP is also obtained. From the expressions of the BEP, we find that in Rayleigh channels, the nonidentical distributions degrade the performance. However, for Ricean case, the nonidentical distributions can have different effects on the performance. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/712432006-01-01T00:00:00Z
- Non-coherent detection for amplify-and-forward relay systems in a Rayleigh fading environmenthttps://scholarbank.nus.edu.sg/handle/10635/71143Title: Non-coherent detection for amplify-and-forward relay systems in a Rayleigh fading environment
Authors: Zhu, Y.; Kam, P.-Y.; Xin, Y.
Abstract: We consider about a multiple relay system operating under amplify-and-forward (AF) protocol and non-coherent modulation and demodulation. When the relays are under long-term power constraints, a near-maximum likelihood (ML) receiver and a diversity combining receiver are proposed. Both the nearML receiver and the diversity combining receiver are expressed in simple closed forms and only rely on the second order statistics of the fading coefficients. Moreover, both of the proposed detectors outperform a non-cooperative system which only has a direct link with non-coherent ML detection in a Rayleigh fading environment. However, when the relay output is under a shortterm power constraint, the ML detector derived here for the non-coherent AF relay performs the same as the non-cooperative system. © 2007 IEEE.
Mon, 01 Jan 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/711432007-01-01T00:00:00Z
- Frequency offset estimation via planar extended Kalman filterhttps://scholarbank.nus.edu.sg/handle/10635/62217Title: Frequency offset estimation via planar extended Kalman filter
Authors: Kam, P.Y.; Teong, L.C.; See, C.C.
Abstract: A planar extended Kalman filter for estimating frequency offset is presented. It extracts the frequency offset from the estimates of its sine and cosine components. Simulations show that this filter acquires more quickly than and tracks better in the steady state than a filter that estimates the frequency offset directly.
Thu, 05 Aug 1993 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/622171993-08-05T00:00:00Z
- Pre-distortion versus post-equalization for IQ mismatch compensation in CO-OFDMhttps://scholarbank.nus.edu.sg/handle/10635/71496Title: Pre-distortion versus post-equalization for IQ mismatch compensation in CO-OFDM
Authors: Cao, S.; Kam, P.-Y.; Yu, C.
Abstract: We compare pre-distortion and post-equalization schemes for compensating IQ mismatch in coherent Optical OFDM systems. It is shown that pre-distortion scheme has much larger tolerance to both phase and amplitude mismatch compared to post-equalization. © 2012 IEEE.
Sun, 01 Jan 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/714962012-01-01T00:00:00Z
- 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
- Receiver sensitivity improvement using decision-aided maximum likelihood phase estimation in coherent optical DQPSK system with nonlinear phase noisehttps://scholarbank.nus.edu.sg/handle/10635/71574Title: Receiver sensitivity improvement using decision-aided maximum likelihood phase estimation in coherent optical DQPSK system with nonlinear phase noise
Authors: Zhang, S.; Kam, P.Y.; Chen, J.; Yu, C.
Abstract: We propose a decision-aided maximum likelihood phase estimation receiver for a nonlinear-phase-noise-dominant coherent optical DQPSK system, which requires only linear computation and improves the receiver sensitivity by 3 dB compared to differential detection. © 2008 Optical Society of America.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/715742008-01-01T00:00:00Z
- Mitigation of nonlinearity based on optimized percentage of dispersion pre-compensation in coherent optical PDM-OFDM systemshttps://scholarbank.nus.edu.sg/handle/10635/70955Title: Mitigation of nonlinearity based on optimized percentage of dispersion pre-compensation in coherent optical PDM-OFDM systems
Authors: Cao, S.; Yu, C.; Kam, P.-Y.
Abstract: The one-step nonlinearity compensation method, i.e., nonlinear phase rotation (NPR), is shown to be affected by the amount of pre-compensated dispersion for coherent optical OFDM system with a dispersion unmanaged link. It is observed that NPR plus optimal percentage, around 50%, of dispersion pre-compensation is performing better than 1-step digital back-propagation (BP), with the same computational complexity. The optimized scheme results in a 2-dBm improvement in optimal launch power as well as 1.75-dB improvement in optimal signal quality compared to 1-step BP after 800-km transmission at the bit rate of 20 Gb/s. © 2012 IEEE.
Sun, 01 Jan 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/709552012-01-01T00:00:00Z
- 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
- Modulation, coding and signal processing for wireless communicationshttps://scholarbank.nus.edu.sg/handle/10635/68580Title: Modulation, coding and signal processing for wireless communications
Authors: Biglieri, E.; Mclane, P.J.; Kam, P.Y.
Fri, 01 Apr 2005 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/685802005-04-01T00:00:00Z
- Sequence estimation over the slow nonselective Rayleigh fading channel with diversity reception and its application to Viterbi decodinghttps://scholarbank.nus.edu.sg/handle/10635/62755Title: Sequence estimation over the slow nonselective Rayleigh fading channel with diversity reception and its application to Viterbi decoding
Authors: Kam, Pooi Yuen; Ching, Hang Moh
Abstract: The authors consider minimum error probability detection of a data sequence transmitted using linear-suppressed carrier modulations, specifically phase-shift keying (PSK), over the Gaussian channel with slow nonselective Rayleigh fading. Complete channel interleaving/deinterleaving and diversity reception are assumed. The problem is considered with application to Viterbi decoding in particular. It is first shown that the two presently available receivers, namely, the conventional maximum likelihood (ML) receiver and the simultaneous estimation receiver, do not perform adequately for this problem. A two-stage receiver is proposed in which the unknown channel fading gains are estimated in the first stage prior to data sequence estimation in the second stage. This receiver is shown to perform adequately, and leads to an efficient receiver/decoder for Viterbi decoding of convolutionally trellis-coded sequences. The issue of optimum estimation of channel fading gains is clarified. The bit error probability of the receiver/decoder is analyzed, and numerical performance results are presented.
Wed, 01 Apr 1992 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/627551992-04-01T00:00:00Z
- 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
- Decision-aided carrier phase estimation for coherent optical communication systemshttps://scholarbank.nus.edu.sg/handle/10635/83601Title: Decision-aided carrier phase estimation for coherent optical communication systems
Authors: Yu, C.; Kam, P.-Y.; Zhang, S.; Chen, J.
Abstract: We review the performance of decision-aided maximum likelihood (DA ML) phase estimation and its adaptive counterpart in different modulation formats. © 2012 OSA.
Sun, 01 Jan 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/836012012-01-01T00:00:00Z
- Cutoff rate of MIMO systems in rayleigh fading channels with PSK signalinghttps://scholarbank.nus.edu.sg/handle/10635/83599Title: Cutoff rate of MIMO systems in rayleigh fading channels with PSK signaling
Authors: Ho, P.; Yar, K.-P.; Kam, P.Y.
Abstract: We derive in this paper the cutoff rate R0 of multiple-input-multiple-output (MIMO) space-time (ST) coding systems operating in Rayleigh fast fading channels with imperfect channel state information at the receiver (CSIR). In contrast to conventional cutoff rate analyzes where R 0 is treated as a continuous variable, we highlight in the paper that when the codeword length N is finite, there is a need to "quantize" R0, as not all code rates are possible. Using the tight upper and lower bounds on the pair-wise error probability (PEP) in [15], we are able to derive in turn tight lower and upper bounds on the cutoff rate of MIMO ST coding systems. Our lower bound on R0 is substantially tighter than that provided by the Chernoff bound for small and medium codeword length N. Asymptotically at large N, our lower bound coincides with the Chernoff bound. It is further shown in the paper that for some MIMO configurations, our upper bound on R0 is simply that of our lower bound shifted by one unit of signal-to-noise-ratio (SNR). As a consequence, both bounds are tight at large SNR. ©2008 IEEE.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/835992008-01-01T00:00:00Z
- 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
- Maximum likelihood carrier phase recovery for coherently orthogonal CPFSK signalshttps://scholarbank.nus.edu.sg/handle/10635/80701Title: Maximum likelihood carrier phase recovery for coherently orthogonal CPFSK signals
Authors: Kam, Pooi Yuen
Abstract: ML estimation of carrier phase for coherently orthogonal continuous-phase frequency-shift-keying (COCPFSK) signals is considered. Although the estimator is in general nonimplementable, its high and low signal-to-noise-ratio approximations both lead to linear readily implementable receiver structures. The high SNR approximation yields a DA receiver, whereas the low SNR approximation yields an NDA receiver. The performance of both receivers in term of bit error probability is analyzed. The existence of an unmodulated component in the sufficient statistical representation of a COCPFSK signal is pointed out, and it is shown how this component enters directly into maximum-like carrier recovery. This leads to interpretation of the NDA receiver as a generalization of the conventional matched-filter envelope-detector receiver. The insights gained here are useful to the problem of ML carrier recovery for Viterbi decoding of continuous phase modulation signals.
Sun, 01 Apr 1990 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/807011990-04-01T00:00:00Z
- MAXIMUM LIKELIHOOD CARRIER PHASE RECOVERY FOR LINEAR SUPPRESSED-CARRIER DIGITAL DATA MODULATIONS.https://scholarbank.nus.edu.sg/handle/10635/80702Title: MAXIMUM LIKELIHOOD CARRIER PHASE RECOVERY FOR LINEAR SUPPRESSED-CARRIER DIGITAL DATA MODULATIONS.
Authors: Kam, Pooi Yuen
Abstract: The problem of maximum-likelihood ML estimation of the phase of a general data-modulated carrier is considered. The shortcomings of current iterative approaches to the problem are pointed out, and the correct conceptual approach is proposed. The true ML estimator is then obtained and found to be nonimplementable. However, by specializing to limits of high and low SNR, the general ML estimator is shown to reduce to implementable DA (decision-aided) and NDA (non-decision-aided) ML estimators, respectively. The DA receiver's performance in terms of phase tracking and symbol error probability can be analyzed, and even the effects of past decision errors on current system performance can be assessed. For circular signal constellations, the DA receiver has a simple and totally linear structure which is easy to implement. The NDA ML estimator is shown to be equivalent to the common carrier loops.
Sun, 01 Jun 1986 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/807021986-06-01T00:00:00Z
- MAXIMUM LIKELIHOOD DIGITAL DATA SEQUENCE ESTIMATION OVER THE GAUSSIAN CHANNEL WITH UNKNOWN CARRIER PHASE.https://scholarbank.nus.edu.sg/handle/10635/80703Title: MAXIMUM LIKELIHOOD DIGITAL DATA SEQUENCE ESTIMATION OVER THE GAUSSIAN CHANNEL WITH UNKNOWN CARRIER PHASE.
Authors: Kam, Pooi Yuen
Abstract: The problem of simultaneous maximum likelihood (ML) estimation of data and carrier phase from a linear suppressed-carrier modulated signal received in the presence of additive white Gaussian noise is considered. The ML detector of the data sequence is derived, and its error probability performance is analyzed. The result shows that the performance loss due to the unknown carrier phase can be reduced by increasing the sequence length. A suboptimum decision-aided subsequence-by-subsequence detector whose complexity does not increase exponentially with sequence length is proposed, and its performance is analyzed.
Wed, 01 Jul 1987 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/807031987-07-01T00:00:00Z
- Generic exponential bounds on the generalized Marcum Q-function via the geometric approachhttps://scholarbank.nus.edu.sg/handle/10635/83759Title: Generic exponential bounds on the generalized Marcum Q-function via the geometric approach
Authors: Li, R.; Kam, P.Y.
Abstract: The generalized Marcum Q-function, Qm(a, b), can be 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 double-struck B signO,b 2m], of 2m dimensions, with radius b, and centered at the origin O. Based on this geometric view, we propose some new generic exponential bounds on Qm(a, b) for the case where m is an integer. These generic exponential bounds are obtained by computing the probability of Z2m lying outside of some bounding geometrical shapes whose surfaces tightly enclose, or are tightly enclosed by the surface of double-struck B sign O,b 2m]. The bounding geometrical shapes used in the derivation consist of an arbitrarily large number of parts. As their closeness of fit with double-struck B sign O,b 2m improves, the generic exponential bounds obtained approach the exact value of Qm(a, b). These generic exponential bounds only involve the exponential function, and thus, are easy to handle in analytical computations. Our numerical results show that when evaluated with a few terms, these generic exponential bounds are much tighter than the existing exponential bounds in the literature for a wide range of arguments. For the case of a > b, our generic upper exponential bound is the first upper exponential bound on Qm(a, b). © 2007 IEEE.
Mon, 01 Jan 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/837592007-01-01T00:00:00Z
- Generic exponential bounds and erfc-bounds on the marcum Q-function via the geometric approachhttps://scholarbank.nus.edu.sg/handle/10635/83758Title: Generic exponential bounds and erfc-bounds on the marcum Q-function via the geometric approach
Authors: Kam, P.Y.; Li, R.
Abstract: The first-order Marcum Q-function, Q(a, b), can be interpreted geometrically as the probability that a complex, Gaussian random variable Z̃ with real mean a, takes on values outside of a circular region C O,b of radius b centered at the origin O. Bounds can thus be easily obtained by computing the probability of Z̃ lying outside of some geometrical shapes whose boundaries tightly enclose, or are tightly enclosed by the boundary of CO,b. In this paper, the bounding shapes are chosen to be a set of sectors or angular sectors of annuli to generate generic exponential bounds, and to be a set of rectangles to generate generic erfcbounds. These generic exponential bounds and erfc-bounds involve an arbitrarily large number of exponential functions and erfc functions, respectively, and are shown to approach the exact value of Q(a, b) as the number of terms involved increases. © 2006 IEEE.
Sun, 01 Jan 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/837582006-01-01T00:00:00Z
- On the performance of decision-aided maximum likelihood and its adaptive phase estimation with nonlinear phase noisehttps://scholarbank.nus.edu.sg/handle/10635/84039Title: On the performance of decision-aided maximum likelihood and its adaptive phase estimation with nonlinear phase noise
Authors: Xu, Z.; Zhang, S.; Kam, P.-Y.; Yu, C.
Abstract: The performance of the adaptive decision-aided maximum likelihood algorithm is investigated in nonlinear-phase-noise-dominant coherent optical MPSK systems. The power penalty at bit-error rate of 10-4 and Q-factor at optimal launched power are both significantly improved. © 2011 National Sun Yat-Sen Univ.
Sat, 01 Jan 2011 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/840392011-01-01T00:00:00Z
- Performance investigation of the joint SPM compensation in a long-haul coherent dual-polarization QPSK systemhttps://scholarbank.nus.edu.sg/handle/10635/84078Title: Performance investigation of the joint SPM compensation in a long-haul coherent dual-polarization QPSK system
Authors: Zhang, S.; Xu, L.; Kam, P.Y.; Yu, C.; Wang, T.
Abstract: The dynamic input power range resulting in BER
Fri, 01 Jan 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/840782010-01-01T00:00:00Z
- Tight bounds on the bit-error probabilities of 2DPSK and 4DPSK in nonselective rician fadinghttps://scholarbank.nus.edu.sg/handle/10635/81290Title: Tight bounds on the bit-error probabilities of 2DPSK and 4DPSK in nonselective rician fading
Authors: Kam, P.Y.; Zhong, C.
Abstract: The bit-error probabilities (BEP's) of matchedfiltered differentially detected two differential phase-shift keying (2DPSK) and 4DPSK over the nonselective Rician-fading channel are studied using the upper bound in. [4J. The bound coincides with the exact error probability result in the binary case and provides very accurate estimates of the BEP in the quadriphase case, especially for high signal-to-noise ratio (SNR) and small K -factor. The bound provides a simple analytical handle for studying the behavior of the error probability as a function of the Doppler spectrum, the Doppler bandwidth, and the K factor. A new result is obtained for the irreducible error-rate floor. The results are useful to the design of digital mobile radio communication systems. © 1998 IEEE.
Thu, 01 Jan 1998 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/812901998-01-01T00:00:00Z
- Tight bounds on Rician-type error probabilities and some applicationshttps://scholarbank.nus.edu.sg/handle/10635/81289Title: Tight bounds on Rician-type error probabilities and some applications
Authors: Kam, Pooi Yuen
Abstract: Consider the classic problem of evaluating the probability that one Rician random variable exceeds another, possibly correlated, Rician random variable. This probability is given by Stein [1] in terms of the Marcum's Q-function, which requires numerical integration on the computer for its evaluation. To facilitate application in many digital communication problems, we derive here tight upper and lower bounds on this probability. The bounds are motivated by a classic result in communication theory, namely, the error probability performance of binary orthogonal signaling over the Gaussian channel with unknown carrier phase. Various applications of the bounds are reported, including the evaluation of the bit error probabilities of MDPSK and MPSK with differential detection and generalized differential detection, respectively. The bounds prove to be tight in all cases. Further applications will be reported in the future.
Thu, 01 Dec 1994 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/812891994-12-01T00:00:00Z
- Analysis of Mth power carrier recovery structure for MPSKhttps://scholarbank.nus.edu.sg/handle/10635/72486Title: Analysis of Mth power carrier recovery structure for MPSK
Authors: Kam, Pooi Yuen; Cheong, Tek Mun
Abstract: In this paper, an approximate, linearized analysis for the phase error probability density function (pdf) for the Mth power carrier recovery structure under the additive white Gaussian noise (AWGN) channel with constant unknown carrier phase and random-walk carrier phase channel models will be presented. From the analysis, the optimum receiver parameters for a given channel condition can then be obtained analytically. With the analysis for the phase error pdf, the bit error rate (BER) can be determined analytically.
Wed, 01 Jan 1997 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/724861997-01-01T00:00:00Z
- DECISION-AIDED MAXIMUM LIKELIHOOD CARRIER RECOVERY FOR QPSK AND ITS BIT ERROR PROBABILITY PERFORMANCE.https://scholarbank.nus.edu.sg/handle/10635/72553Title: DECISION-AIDED MAXIMUM LIKELIHOOD CARRIER RECOVERY FOR QPSK AND ITS BIT ERROR PROBABILITY PERFORMANCE.
Authors: Kam, Pooi Yuen; Tjhung, Tjeng Thiang
Abstract: A QPSK signal treated as two BPSK signals in quadrature and received with an unknown phase shift in the presence of additive white Gaussian noise is considered. The decision-aided maximum-likelihood estimator of the carrier phase is derived. The error rate performance of data detection in the in-phase and quadrature-phase (I and Q) channels is obtained using this estimate and results on the distribution of the angle between two vectors perturbed by Gaussian noise. These error rate results enable us to quantify the effects of crosstalk interference on the performance of I and Q BPSK data channels to be quantified.
Wed, 01 Jan 1986 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/725531986-01-01T00:00:00Z
- ERROR PROBABILITY FOR OPTICAL FIBRE SYSTEMS IN THE PRESENCE OF MODAL NOISE.https://scholarbank.nus.edu.sg/handle/10635/72613Title: ERROR PROBABILITY FOR OPTICAL FIBRE SYSTEMS IN THE PRESENCE OF MODAL NOISE.
Authors: Chan, Peter; Tjhung, T.T.; Kam, P.Y.
Abstract: A Rayleigh probability distribution is used to model the received optical power fluctuation in a digital fiber-optic system affected by modal noise. New recursive formulas for the moments of the receiver output current are obtained that can be used in the Gaussian quadrative rule approximation of the error probability integral. Error rates have been calculated for a varying degree of modal noise disturbance. Results show that at least an additional 7. 5 dB of received optical power is needed when modal noise is present for an error rate of 10** minus **1**0.
Wed, 01 Jan 1986 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/726131986-01-01T00:00:00Z
- Sequence estimation over the slow nonselective Rayleigh fading channel with diversity reception and its application to Viterbi decodinghttps://scholarbank.nus.edu.sg/handle/10635/81152Title: Sequence estimation over the slow nonselective Rayleigh fading channel with diversity reception and its application to Viterbi decoding
Authors: Kam, Pooi Yuen; Ching, Hang Moh
Abstract: The authors consider minimum error probability detection of a data sequence transmitted using linear-suppressed carrier modulations, specifically phase-shift keying (PSK), over the Gaussian channel with slow nonselective Rayleigh fading. Complete channel interleaving/deinterleaving and diversity reception are assumed. The problem is considered with application to Viterbi decoding in particular. It is first shown that the two presently available receivers, namely, the conventional maximum likelihood (ML) receiver and the simultaneous estimation receiver, do not perform adequately for this problem. A two-stage receiver is proposed in which the unknown channel fading gains are estimated in the first stage prior to data sequence estimation in the second stage. This receiver is shown to perform adequately, and leads to an efficient receiver/decoder for Viterbi decoding of convolutionally trellis-coded sequences. The issue of optimum estimation of channel fading gains is clarified. The bit error probability of the receiver/decoder is analyzed, and numerical performance results are presented.
Wed, 01 Apr 1992 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/811521992-04-01T00:00:00Z
- MINIMUM ERROR PROBABILITY RECEIVER FOR THE GAUSSIAN CHANNEL WITH A RANDOM COMPLEX GAIN.https://scholarbank.nus.edu.sg/handle/10635/72744Title: MINIMUM ERROR PROBABILITY RECEIVER FOR THE GAUSSIAN CHANNEL WITH A RANDOM COMPLEX GAIN.
Authors: Kam, Pooi Yuen
Abstract: The author considers data transmission using linear suppressed-carrier modulations over the Gaussian channel with a random complex gain. The channel model applies in practice to the random phase channel and the nonselective Rayleigh fading channel. The author derives the minimum-error-probability receiver, and shows that the receiver is in general nonimplementable. The receiver has a detector estimator structure, and it is the computational burden of the estimator which renders the receiver nonimplementable. A suboptimal decision-feedback implementation is suggested, and the results are specialized to the random-phase channel and the Rayleigh fading channel.
Thu, 01 Jan 1987 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/727441987-01-01T00:00:00Z
- Some new results and interpretations concerning binary orthogonal signaling over the Gaussian channel with unknown phase/fadinghttps://scholarbank.nus.edu.sg/handle/10635/72933Title: Some new results and interpretations concerning binary orthogonal signaling over the Gaussian channel with unknown phase/fading
Authors: Kam, Pooi Yuen
Abstract: Summary form only given, as follows. The well-known problem of binary orthogonal signaling over the Gaussian noise channel with unknown phase/fading is considered. By viewing the problem in a rotated coordinate system, the orthogonal signal structure can be considered as the combination of an antipodal signal set and an unmodulated component (pilot tone) for channel measurement. This allows the author to show that as far as data detection is concerned the optimum matched-filter envelope detector is identical to a novel detector-estimator receiver in which the detector performs partially coherent detection using an absolute coherent reference generated by the estimator from the channel measurement provided by the pilot-tone component of the orthogonal signal structure. This detector-estimator interpretation of the optimum receiver shows that it is wrong to refer to the latter as a noncoherent receiver. It also leads to the development of new approaches for analyzing the error probability performance of the receiver. In particular, for the Rician channel, an exponential Chernoff upper bound is obtained, and an expression is also obtained for the case of slight fading.
Mon, 01 Jan 1990 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/729331990-01-01T00:00:00Z
- Adaptive symbol-by-symbol reception of PSK on channels with unknown phasehttps://scholarbank.nus.edu.sg/handle/10635/72469Title: Adaptive symbol-by-symbol reception of PSK on channels with unknown phase
Authors: Kam, Pooi Yuen; Chua, Keng Hong; Yu, Xiaofeng
Abstract: We propose an adaptive symbol-by-symbol receiver for phase shift-keying (PSK) over the Gaussian channel with unknown carrier phase. The statistical properties of the carrier phase are assumed unknown to the receiver, other than the fact that it is slowly varying so that a piecewise-constant approximation can be made. The coherent reference for detection is obtained using a first-order filter whose gain is adapted on-line, based on the received signal samples. The performance of the receiver is analyzed both via analysis and simulations.
Wed, 01 Jan 1997 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/724691997-01-01T00:00:00Z
- CARRIER PHASE RECOVERY FOR BPSK USING MAXIMUM LIKELIHOOD ESTIMATION THEORY.https://scholarbank.nus.edu.sg/handle/10635/72513Title: CARRIER PHASE RECOVERY FOR BPSK USING MAXIMUM LIKELIHOOD ESTIMATION THEORY.
Authors: Kam, Pooi Yuen
Abstract: The maximum-likelihood (ML) estimation of carrier phase for BPSK in AWGN is considered. The solution is a decision-aided (DA) ML estimator for high SNR and a (non-decision-aided) NDA ML estimator for low SNR. The DA ML estimator leads to a simple, totally linear receiver structure which involves no VCO. The phase tracking and error probability performance of this receiver is analyzed. Even the effects of past decision errors on current system performance can be assessed. The NDA ML estimator is shown to be equivalent to the common carrier loops.
Tue, 01 Jan 1985 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/725131985-01-01T00:00:00Z
- Open-loop tanlock carrier recovery structure for BPSK and its performancehttps://scholarbank.nus.edu.sg/handle/10635/81640Title: Open-loop tanlock carrier recovery structure for BPSK and its performance
Authors: Kam, Pooi Yuen
Abstract: The tanlock carrier recovery structure has been shown to be the low SNR approximation to the optimum ML carrier phase estimator for a carrier with linear data modulations such as MPSK. It has long been known to have better performance than a Costas' loop or a squarer/PLL for BPSK, because its tangent-function phase detector characteristic has an extended linear range compared to the sine-function phase detector characteristic of the latter loops. Its implementation in conventional closed-loop form, however, requires the use of a divider which suffers from the problem of output overflow when the input divisor signal becomes very small. We suggest here an open-loop implementation which does not require the use of a divider and a VCO. The operational and performance advantages of this open-loop implementation over the conventional closed-loop implementation are pointed out. Some sample BER results for a coherent receiver employing this open-loop tanlock carrier recovery system are obtained via computer simulations. The results show that the receiver achieves significant performance gains over differential detection.
Sun, 01 Jan 1995 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/816401995-01-01T00:00:00Z
- MINIMUM ERROR PROBABILITY RECEIVER FOR THE GAUSSIAN CHANNEL WITH A RANDOM COMPLEX GAIN.https://scholarbank.nus.edu.sg/handle/10635/81539Title: MINIMUM ERROR PROBABILITY RECEIVER FOR THE GAUSSIAN CHANNEL WITH A RANDOM COMPLEX GAIN.
Authors: Kam, Pooi Yuen
Abstract: The author considers data transmission using linear suppressed-carrier modulations over the Gaussian channel with a random complex gain. The channel model applies in practice to the random phase channel and the nonselective Rayleigh fading channel. The author derives the minimum-error-probability receiver, and shows that the receiver is in general nonimplementable. The receiver has a detector estimator structure, and it is the computational burden of the estimator which renders the receiver nonimplementable. A suboptimal decision-feedback implementation is suggested, and the results are specialized to the random-phase channel and the Rayleigh fading channel.
Thu, 01 Jan 1987 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/815391987-01-01T00:00:00Z
- Viterbi-type algorithm for efficient estimation of M-PSK sequences over the Gaussian channel with unknown carrier phasehttps://scholarbank.nus.edu.sg/handle/10635/81351Title: Viterbi-type algorithm for efficient estimation of M-PSK sequences over the Gaussian channel with unknown carrier phase
Authors: Kam, Pooi Yuen; Sinha, Pranesh
Abstract: A Viterbi-type algorithm for the efficient estimation of a convolutionally/trellis coded, or uncoded M-PSK sequence over the Gaussian channel with unknown carrier phase is presented. It performs coherent detection of M-PSK sequences with no explicit recovery of coherent references. The metric computations involve only linear operations. Theoretical and simulated performance results are presented for various carrier phase processes.
Fri, 01 Sep 1995 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/813511995-09-01T00:00:00Z
- Viterbi detection with simultaneous suboptimal maximum likelihood carrier phase estimationhttps://scholarbank.nus.edu.sg/handle/10635/81350Title: Viterbi detection with simultaneous suboptimal maximum likelihood carrier phase estimation
Authors: Kam, Pooi Y.; Ho, Hsi C.
Abstract: The authors consider maximum-likelihood (ML) detection of convolutionally coded data over the AWGN channel with unknown carrier phase. A receiver is developed for simultaneous ML data decoding and suboptimal ML carrier-phase estimation. The receiver is readily implementable and, for a circular signal constellation, it is totally linear. Computer simulations using two different models of the time-varying carrier phase indicate that the receiver provides good bit error probability performance.
Thu, 01 Dec 1988 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/813501988-12-01T00:00:00Z
- VITERBI DECODER INCORPORATING SUBOPTIMAL MAXIMUM LIKELIHOOD CARRIER PHASE ESTIMATION.https://scholarbank.nus.edu.sg/handle/10635/81806Title: VITERBI DECODER INCORPORATING SUBOPTIMAL MAXIMUM LIKELIHOOD CARRIER PHASE ESTIMATION.
Authors: Kam, Pooi Yuen; Ho, Hsi Chong
Abstract: The authors consider the detection of convolutionally coded data received over the additive white Gaussian noise channel with unknown carrier phase. An algorithm is developed for simultaneous maximum-likelihood (ML) data decoding and suboptimal ML carrier-phase estimation. The algorithm does not increase the number of states in the Viterbi decoder, and it readily implementable. For a circular signal constellation, the algorithm leads to a totally linear receiver. The performance of the algorithm is obtained using computer simulations with a time-varying phase given by two different models. The error-rate results indicate that the algorithm provides good performance.
Thu, 01 Jan 1987 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/818061987-01-01T00:00:00Z
- Some new results and interpretations concerning binary orthogonal signaling over the Gaussian channel with unknown phase/fadinghttps://scholarbank.nus.edu.sg/handle/10635/81762Title: Some new results and interpretations concerning binary orthogonal signaling over the Gaussian channel with unknown phase/fading
Authors: Kam, Pooi Yuen
Abstract: Summary form only given, as follows. The well-known problem of binary orthogonal signaling over the Gaussian noise channel with unknown phase/fading is considered. By viewing the problem in a rotated coordinate system, the orthogonal signal structure can be considered as the combination of an antipodal signal set and an unmodulated component (pilot tone) for channel measurement. This allows the author to show that as far as data detection is concerned the optimum matched-filter envelope detector is identical to a novel detector-estimator receiver in which the detector performs partially coherent detection using an absolute coherent reference generated by the estimator from the channel measurement provided by the pilot-tone component of the orthogonal signal structure. This detector-estimator interpretation of the optimum receiver shows that it is wrong to refer to the latter as a noncoherent receiver. It also leads to the development of new approaches for analyzing the error probability performance of the receiver. In particular, for the Rician channel, an exponential Chernoff upper bound is obtained, and an expression is also obtained for the case of slight fading.
Mon, 01 Jan 1990 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/817621990-01-01T00:00:00Z
- Tight bounds on the bit error probabilities of MDPSK over the nonselective Rician fading channelhttps://scholarbank.nus.edu.sg/handle/10635/81785Title: Tight bounds on the bit error probabilities of MDPSK over the nonselective Rician fading channel
Authors: Kam, Pooi Yuen; Zhong, Cheng
Abstract: The bit error probabilities of BDPSK and QDPSK over the Gaussian channel with nonselective Rician fading are studied using the bounds obtained recently in [2]. These bounds are shown to coincide with the exact error probability results in the former binary case, and to provide very accurate estimates of the bit error probability in the latter quadriphase case, especially in the limit of high SNR and in the limit of small K- factor. The bounds provide a simple analytical handle by which one can study the behavior of the error probability as a function of various quantities such as the Doppler spectrum, the Doppler bandwidth and the K-factor. New results are obtained, in particular, for the irreducible error rate floor and the SNR at which this error floor sets in. The results are useful to the design of the new generations of digital mobile radio communication systems.
Sun, 01 Jan 1995 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/817851995-01-01T00:00:00Z