Unequal error protection on turbo-encoder outputbits

Mohammadi, A.H.S.; Khandani, Amir K.

doi:10.1049/el:19970178

Cited by 11 publications

(5 citation statements)

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“…In typical turbo codes, the squared Euclidean distances between all-zero-codeword and the codeword with weight j is r j E b . Implementing UPA scheme in turbo code system can be viewed as changing the SNR of the transmitted bits while keeping the average SNR constant [9,10]. In order to implement UPA scheme, we need to modify the Euclidean distance [9,10].…”

Section: Performance Bound For the Proposed Asymmetrical Turbo Code Umentioning

confidence: 99%

“…Implementing UPA scheme in turbo code system can be viewed as changing the SNR of the transmitted bits while keeping the average SNR constant [9,10]. In order to implement UPA scheme, we need to modify the Euclidean distance [9,10]. In each frame, we have systematic bits, w, parity bits d 1 and d 2 with power fractions α, β and χ, respectively.…”

Section: Performance Bound For the Proposed Asymmetrical Turbo Code Umentioning

confidence: 99%

“…This way of typical power allocation does not guarantee an optimal power allocation, which produces less optimum performance. Therefore, in order to overcome this B. Balamuralithara (B) Faculty of Engineering, Multimedia University, Cyberjaya, Selangor 63100, Malaysia e-mail: bmt.balakrishnan@mmu.edu.my ∈ problem, a UPA scheme was introduced by Mohammadi and Khandani in [3,9,10]. This method is used to improve the code performance by allocating different power levels to systematic bits (d) and both parity bits (C1 and C2) refer to Fig.…”

Section: Introductionmentioning

confidence: 99%

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A New Unequal Power Allocation Scheme for Asymmetric Turbo Code System

Balakrishnan

2008

Wireless Pers Commun

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In this paper, a modified unequal power allocation scheme for the different bits of asymmetric turbo encoder has been investigated to enhance the performance. The simulation results and performance bound for the asymmetric turbo code with modified Unequal Power Allocation (UPA) scheme are obtained and compared with the system with typical UPA and without UPA. From the performance results, it is observed that the proposed asymmetric turbo code with modified UPA performs better than the system without UPA and with typical UPA and it provides a coding gain of 0.4-0.52 dB.

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Section: Performance Bound For the Proposed Asymmetrical Turbo Code Umentioning

confidence: 99%

Section: Performance Bound For the Proposed Asymmetrical Turbo Code Umentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A New Unequal Power Allocation Scheme for Asymmetric Turbo Code System

Balakrishnan

2008

Wireless Pers Commun

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“…This result is due to the fact that the PEP between symbols in different clusters is much smaller than that between symbols in the same cluster, so that the second term in the right-hand side of (C-4) is negligible when is small. The unequal pairwise error characteristic of the ST scheme may be useful in some applications where information and redundant bits have different significance, such as with a turbo code [21]. In these cases, we may encode bits into a PPM symbol by using more significant bits to select a cluster and less significant bits to select a position in the cluster.…”

Section: B Selective Transmission Schemementioning

confidence: 99%

Hybrid pulse position modulation/ultrashort light pulse code-division multiple-access systems-part II: time-space processor and modified schemes

Kim

Marom

Milstein

et al. 2003

IEEE Trans. Commun.

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In Part I of this two-part paper, we proposed and investigated a hybrid pulse position modulation/ultrashort light pulse code-division multiple-access (PPM/ULP-CDMA) system for ultrafast optical communication networks. In the proposed scheme, the large bandwidth of an ULP is efficiently utilized by virtue of the very high time resolution of a time-space processor. In this paper, more detailed analysis and discussion on the receiver scheme using the time-space processor is presented; nonideal performance of the time-space processor, including the reference pulse realization problem, as well as amplifier and detector noise, are taken into account. Discussions on physically achievable ranges of the system parameters that determine the performance of the proposed PPM/ULP-CDMA system are also made based upon current, state of the art technology. As remedies to overcome the physical limitations on the system parameters, two modified modulation/demodulation schemes are proposed and investigated to enhance the performance of the hybrid PPM/ULP-CDMA system. Index Terms-Optical code-division multiple access (CDMA), pulse position modulation (PPM), time-space processor, ultrashort light pulse (ULP). I. INTRODUCTION I N [1], we proposed and investigated a hybrid pulse position modulation/ultrashort light pulse code-division multiple-access (PPM/ULP-CDMA) system to provide ultrafast communication in multiple-access optical networks. In the proposed hybrid PPM/ULP-CDMA system, a pulse position modulation (PPM) format with very short pulse separation was used to utilize the given large bandwidth of an ultrashort

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“…In order to eliminate the noise correlation between the systematic and first parity check bits, we used an extra interleaver for the systematic bits before mapping them to the orthogonal signals. For this system, we changed the labeling method such that the protection over the systematic bits is less than the the protection for parity check bits [9].…”

Section: A Combined Turbo-code and 8-psk Modulationmentioning

confidence: 99%

Combined turbo-code and modulation for CDMA wireless communications

Mohammadi

Zhuang²

VTC '98. 48th IEEE Vehicular Technology Conference. Pathway to Global Wireless Revolution (Cat. No.98CH36151)

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This paper investigates a system of combined turbo-code and M-ary orthogonal signaling for CDMA wireless communications. The performance of the system is studied over AWGN channel with coherent and noncoherent detection for short frame lengths, with emphasis on the effect of noise correlation between the coded bits. It is shown that eliminating this correlation is important in improving the transmission performance of the system. When a 6CHadamard signaling is employed, the performance of the system is improved by approximately 0.8 dB at a signal-to-noise ratio (SNR) per information bit of 4 dB, and the improvement increases as the SNR increases. It is also shown that for the bit error rate (BER) of interest in voice communication systems, 8-Hadamard mapping performs almost as well as 64-Hadamard mapping, with less complexity and delay.

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Unequal error protection on turbo-encoder outputbits

Cited by 11 publications

References 1 publication

A New Unequal Power Allocation Scheme for Asymmetric Turbo Code System

A New Unequal Power Allocation Scheme for Asymmetric Turbo Code System

Hybrid pulse position modulation/ultrashort light pulse code-division multiple-access systems-part II: time-space processor and modified schemes

Combined turbo-code and modulation for CDMA wireless communications

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