Pilot-channel-assisted binary phase-shift keying (PCA-BPSK) in direct-sequence code-division multiple-access (DS-CDMA) systems is investigated, The loss due to imperfect channel estimation is calculated, and the pilot...
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Pilot-channel-assisted binary phase-shift keying (PCA-BPSK) in direct-sequence code-division multiple-access (DS-CDMA) systems is investigated, The loss due to imperfect channel estimation is calculated, and the pilot-to-data channel power ratio is optimized analytically. The results show the effects of the various parameters and provide a suitable tool for system design.
作者：
Hole, KJLaboratory of Chromatography
DEPg.Fac.Quimica Universidad Nacional Autonoma de Mexico Circuito interior Cd Universitaria/CP 04510 Mexico D.F.Mexico
Many classes of rate (n - 1)/n convolutional codes are shown to be asymptotically catastrophic.
Many classes of rate (n - 1)/n convolutional codes are shown to be asymptotically catastrophic.
In this letter, we construct new encoder-independent upper bounds on the free distance for the rate (n-1)/n convolutional encoders that are formed by using rate 1/2 encoders and combined with 2(n)-level constant-envel...
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In this letter, we construct new encoder-independent upper bounds on the free distance for the rate (n-1)/n convolutional encoders that are formed by using rate 1/2 encoders and combined with 2(n)-level constant-envelope full-response CPFSK signals of single-h, by generalizing the bounding technique employed for the existing bounds. The new bounds coincide with the existing bounds for hless than or equal to0.25, but are generally better for h>0.25. We also present actual encoder combinations achieving the constructed new bounds with short constraint lengths.
We first present the traditional decoding approach that employs the common pilot-channel-based maximal ratio combining and the Viterbi or iterative decoding cannot achieve the optimal error-rate performance for downli...
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We first present the traditional decoding approach that employs the common pilot-channel-based maximal ratio combining and the Viterbi or iterative decoding cannot achieve the optimal error-rate performance for downlink direct-sequence code-division multiple-access (CDMA) signals when a fast power control technique is applied together with a convolutional or turbo coding. Then, as an efficient method to realize a nearly optimal decoding, we propose a branch metric power readjustment (BMPR) technique, where the downlink power control command generated by the mobile station is used not only to adjust the base station power in the transmitter side, but also to readjust the decoder input branch metric power in the receiver side. Numerical results show that the BMPR technique applied to the IMT-2000 wideband-CDMA system can improve the transmit power utilization by up to 0.4 dB for the block-error rate of 10(-2).
It is shown empirically that the number of good periodically time-varying convolutional codes increases exponentially with the period for any set of parameters. Hence, they can be used to enhance the security of crypt...
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It is shown empirically that the number of good periodically time-varying convolutional codes increases exponentially with the period for any set of parameters. Hence, they can be used to enhance the security of cryptosystems without sacrificing error correction capability. It is shown that some periodically time-varying convolutional codes improve the free distance compared with fixed codes.
Choosing a convolutional encoder over a ring with feedback may not lead to a suitable component code for parallel or serial concatenation. A simple criterion is derived that allows to check whether a rational encoding...
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Choosing a convolutional encoder over a ring with feedback may not lead to a suitable component code for parallel or serial concatenation. A simple criterion is derived that allows to check whether a rational encoding matrix generating some convolutional code over the integer ring Z(pm) (p prime) has exclusively infinite impulse responses.
A scheme is proposed to decode a tail-biting convolutional code based on its Tanner graph, which is traditionally done using a forward-backward MAP algorithm. Therefore, decoding may be performed using a standard sum-...
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A scheme is proposed to decode a tail-biting convolutional code based on its Tanner graph, which is traditionally done using a forward-backward MAP algorithm. Therefore, decoding may be performed using a standard sum-product algorithm. With respect to decoding based on trellis, all variables in a Tanner graph are binary, which may lead to complexity reduction. A min-sum algorithm is used to decrease the analogue circuit complexity. Simulation shows there is no significant degradation compared with more complex traditional methods.
convolutional codes have appeared in the literature endowed with sufficient additional algebraic structure to be considered as (left) ideals of a (code-ambient) automorphism-twisted polynomial ring with coefficients i...
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convolutional codes have appeared in the literature endowed with sufficient additional algebraic structure to be considered as (left) ideals of a (code-ambient) automorphism-twisted polynomial ring with coefficients in a (word-ambient) semisimple finite group ring. In this paper we extend the present scope of the theory by considering a code-ambient twisted polynomial ring having, in addition to an automorphism sigma, the action of a sigma-derivation delta. In addition, we develop the basic theory without any specific restrictions for the semisimple finite word-ambient ring. This second element therefore extends even the original notions of both cyclic and group convolutional codes considered thus far in the literature. Among other results, in this paper we develop a matrix-based approach to the study of our extended notion of group convolutional codes (and therefore of cyclic convolutional codes as well), inspired by the use of circulant matrices by Gluesing-Luerssen and Schmale, and then use it to extend to this level the results on the existence of dual codes that were originally established by those authors for cyclic codes (in the narrower sense without a sigma-derivation). Various examples illustrate the potential value of extending the search for good convolutional codes in this direction. (c) 2012 Elsevier B.V. All rights reserved.
We propose an efficient block least-mean-square (BLMS) adaptive algorithm, in conjunction with error control coding, for direct-sequence code division multiple access (DS-CDMA) systems. The proposed adaptive receiver ...
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We propose an efficient block least-mean-square (BLMS) adaptive algorithm, in conjunction with error control coding, for direct-sequence code division multiple access (DS-CDMA) systems. The proposed adaptive receiver incorporates decision feedback detection and channel encoding in order to improve the performance of the standard LMS algorithm in convolutionally coded systems. The BLMS algorithm involves two modes of operation: (i) The training mode where an uncoded training sequence is used for initial filter tap-weights adaptation, and (ii) the decision-directed where the filter weights are adapted, using the BLMS algorithm, after decoding/encoding operation. It is shown that the proposed adaptive receiver structure is able to compensate for the signal-to-noise ratio (SNR) loss incurred due to the switching from uncoded training mode to coded decision-directed mode. Our results show that by using the proposed adaptive receiver (with decision feedback block adaptation) one can achieve a much better performance than both the coded LMS with no decision feedback employed. The convergence behavior of the proposed BLMS receiver is simulated and compared to the standard LMS with and without channel coding. We also examine the steady-state bit-error rate (BER) performance of the proposed adaptive BLMS and standard LMS, both with convolutional coding, where we show that the former is more superior than the latter especially at large SNRs (SNR >= 9 dB).
Whilst the laboratory works at faculties providing education on the field of electronics and communication support the technical knowledge of students, they also develop their implementation abilities. The fact that t...
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Whilst the laboratory works at faculties providing education on the field of electronics and communication support the technical knowledge of students, they also develop their implementation abilities. The fact that there is less equipment requiring advanced technologies in laboratories, enforces the students to group works and thus limits working time and their contribution to the experiments. Contemporary computer technology provides the possibility for establishing alternative laboratories, environments in which the students can perform implementations without the restrictions of location and time. In this work, real time remote accessible experiment sets are prepared regarding coding techniques with error control. It is provided that the students can connect to the web based laboratory system via any computer on the LAN and make experiments. In this laboratory, the student will perform real time implementations without the restriction of location and time and strengthen their theoretical knowledge.
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