Browsing by Author "SU, YT"

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ADAPTIVE BLIND EQUALIZATION USING 2ND-ORDER AND HIGHER-ORDER STATISTICS
(1995-01-01)
UENG, FB
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SU, YT
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電信工程研究所
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友訊交大聯合研發中心
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Institute of Communications Engineering
This paper presents two classes of adaptive blind algorithms based on second- and higher order statistics. The first class contains fast recursive algorithms whose cost functions involve second and third- or fourth-order cumulants. These algorithms are stochastic gradient-based but have structures similar to the fast transversal filters (FTF) algorithms. The second class is composed of two stages: the first stage uses a gradient adaptive lattice (GAL) while the second stage employs a higher order-cumulant (HOC) based least mean squares (LMS) filter. The computational loads for these algorithms are all linearly proportional to the number of taps used, Furthermore, the second class, as various numerical examples indicate, yields very fast convergence rates and low steady state mean square errors (MSE) and intersymbol interference (ISI), MSE convergence analyses for the proposed algorithms are also provided and compared with simulation results.
ADAPTIVE BLIND EQUALIZATION USING 2ND-ORDER AND HIGHER-ORDER STATISTICS (VOL 13, PG 132, 1995)
(1995-02-01)
UENG, FB
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SU, YT
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交大名義發表
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電信工程研究所
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National Chiao Tung University
ADAPTIVE IIR BLIND ALGORITHMS
(1995-06-08)
UENG, FB
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SU, YT
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交大名義發表
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電信工程研究所
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National Chiao Tung University
Infinite impulse response (IIR) filtering, when compared with finite impulse response (FIR) filtering, can result in a substantial computational saving and small mean-squared error (MSE). Two IIR blind algorithms based on the second and fourth order cumulants are presented. Simulation results indicate that the proposed IIR blind algorithms not only have faster convergence rates but also lower MSEs than their FIR counterparts.
CUTOFF RATES OF MULTICHANNEL MFSK AND DPSK SIGNALS IN MOBILE SATELLITE-COMMUNICATIONS
(1995-02-01)
SU, YT
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CHEN, JY
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電信工程研究所
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友訊交大聯合研發中心
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Institute of Communications Engineering
This paper studies the coded performance of multichannel MFSK and DPSK signalings in mobile satellite environments characterized by various kinds of multipath fading. Rician, Rician/lognormal, and a convex combination of Rician and Rician/lognormal or Rayleigh/lognormal distributions are used to model these communication channels. We investigate the minimum average signal-energy-to-noise ratio required to yield a cutoff rate that is greater than or equal to a given code rate. Also examined are system design issues such as the effect of quantization and metric conversion, the choice between binary codes and M-ary symbol codes, the optimization of the diversity order and the signal size, and the order of deinterleaving and diversity combining. Numerical examples are given to answer concerns raised by these issues.
DECODING METRICS FOR SLOW FREQUENCY-HOPPED DPSK SYSTEMS
(1992-10-01)
SU, YT
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電信工程研究所
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友訊交大聯合研發中心
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Institute of Communications Engineering
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D Link NCTU Joint Res Ctr
A variety of soft-decision decoding metrics for slow frequency-hopped, differential phase shift keyed spread-spectrum systems are studied. The computational cut-off rates in the presence of partial band noise jamming for these metrics are analysed. The usefulness of various degrees of side information, the effectiveness of limiting and quantisation when side information is not available, and the importance of a judicious choice of the quantisation step size are demonstrated. Monte-Carlo type simulations for the system encoded by Odenwalder's (7, 1/2) code are conducted, the resulting BERs reveal that close approximations can be attained by estimations calculated from a known closed-form formula.
DIVERSITY COMBINING CONSIDERATIONS FOR INCOHERENT FREQUENCY-HOPPING MULTIPLE-ACCESS SYSTEMS
(1995-02-01)
HUNG, CP
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SU, YT
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電控工程研究所
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電信工程研究所
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Institute of Electrical and Control Engineering
This paper studies the problem of diversity combining for frequency-hopped multiple access (FHMA) systems that operate in a mobile satellite environment characterized by frequency-nonselective Rician multipath fading. The modulation scheme considered is the incoherent M-ary frequency-shift keying (MFSK). The optimal diversity combining rule is derived under the assumptions that the number of active users (K) in the system is known, all users are chip (hop)-synchronous, and each user employs a random FH address, We suggest practical implementations that are close approximations of the optimal rule and examine the effects of various system parameters on the resulting receivers. The bit error probability performance is analyzed and numerical examples are provided, The effects of the diversity order (L), the signaling size (M) and unequal received powers are examined and related system design concerns such as system capacity and spectral efficiency are evaluated as well.
DOWNLINK POWER-CONTROL ALGORITHMS FOR CELLULAR RADIO SYSTEMS
(1995-02-01)
LEE, TH
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LIN, JC
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SU, YT
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電控工程研究所
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電信工程研究所
Power control is an effective technique to reduce cochannel interference and increase capacity for cellular radio systems, Optimum centralized power control can minimize the outage probability, but requires the information of all link gains in real time, which is very difficult to successfully implement for a large system; besides, the computational complexity of an optimum power control algorithm makes it impractical for real implementations. In this paper, we propose some centralized power control algorithms with reasonable computational complexity, One of the algorithms, called the SMIRA algorithm, has an outage probability that is very close to the minimum, We also study a class of distributed power control algorithms that can achieve a balanced carrier-to-interference ratio with probability one, Among the class of algorithms, we found that the one proposed in [6] gives the minimum outage probability.
ON A SATELLITE COVERAGE PROBLEM
(1995-07-01)
CHI, DT
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SU, YT
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電信工程研究所
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電子與資訊研究中心
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Institute of Communications Engineering
The earth coverage area for a satellite in an Earth synchronous orbit with a non-zero inclination angle is a function of the time of day. Locating the area where an Earth terminal can establish a link with a geosynchronous satellite at a certain period of the day is of great concern to system designers: A special case of much interest is when the time period of satellite coverage is 24 h. Two simple and rapid algorithms for locating 24 h satellite coverage areas are presented. One of the proposed algorithms can also be applied to determine other airborne antenna coverage problems.
PERFORMANCE OF FAST FH MFSK SIGNALS IN JAMMED BINARY CHANNELS
(1994-07-01)
SU, YT
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CHANG, RC
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電信工程研究所
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友訊交大聯合研發中心
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Institute of Communications Engineering
Soft-decision decoded performance of fast frequency-hopped (FH) M-ary FSK signals over partial band noise jammed binary channels is studied. The effects of metrics conversion, quantization, and the presence of regenerative nodes on the system's cutoff rate performance are investigated. It is found that the conversion from an M-ary metric to a binary one suffers only negligible degradations. For communication links without regenerative nodes, as expected, the infinite-bit soft-decision is the optimal metric, followed by finite-bit soft decision and then hard-decision. For those with regenerative nodes, however, the infinite-bit soft-decision is outperformed by the hard-decision, but the finite-bit soft-decision decoder still keeps its edge over the latter. The issue concerning the order of metric conversion and diversity combining is also analyzed. Numerical results indicate that the conclusion obtained by an earlier simulation report addressing a similar design alternative in fading channels is valid for jammed binary channels, as well. That is, the precombining metric conversion technique gives up only minor performance degradations when compared to the more sophisticated postcombining metric conversion technique.
POWER-CONTROL ALGORITHM FOR CELLULAR RADIO SYSTEMS
(1994-02-03)
LIN, JC
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LEE, TH
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SU, YT
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電控工程研究所
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電信工程研究所
In a recent paper, Zander presented an optimum transmitter power control scheme to minimise the outage probability for cellular systems and proposed the stepwise removal algorithm (SRA) for use in practical implementations. In the Letter, the authors present a new power control algorithm which considers the transmitter power together with fink gams. The algorithm provides better outage probability with only a negligible increase in computational complexity.
The effect of imperfect power control on outage probability in a cellular mobile system
(1995)
LIN, JC
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LIN, YC
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LEE, TH
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SU, YT
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電控工程研究所