DVB-RCS Next Generation을 위한 Third-dimension Turbo Code 분석

위성 통신은 넓은 지역에 통신 서비스를 제공하는 광역 네트워크이다. 하지만, 위성 통신은 대역폭이 제한되고 매우 긴 전파 지연 시간과 높은 BER(Bit Error Rate)로 인해 위성 통신을 고려하지 않은 TCP의 성능이 저하 된다. 본 논문에서는 위성 통신에서의 TCP 성능을 향상시키기 위해 DVB-RCS(Digital Video Broadcasting-Return Channel via Satellite) 네트워크 환경을 고려한 cross-layer 기반 PEP(Performance Enhancing Proxy) 기술을 제안한다. 제안하는 프로토콜은 TCP와 링크 계층 간 위성 자원 할당 정보를 정보 교환을 통해 최적의 TCP CWND(Congestion Window)를 설정한다. 제안한 프로토콜의 성능 평가를 위해 리눅스 기반의 PEP 테스트 베드를 구현하였다. 성능 평가 결과 다양한 BER에서 제안한 프로토콜은 위성 자원 할당 정보를 이용하여 최적의 TCP CWND 크기를 설정하기 때문에 단일 및 다중 세션 환경에서 기존 TCP 보다 제안한 프로토콜이 더 좋은 성능을 보여준다는 것을 확인할 수 있었다. Satellite communication is a wide area network (WAN) which provides communication service worldwide. However, the performance of TCP can be seriously degraded in the satellite networks due to limited bandwidth, long round-trip time (RTT) and high bit error rate (BER) over satellite links. In order to improve the performance of TCP, this paper proposes cross-layer Performance Enhancing Proxy (PEP) in digital video broadcasting-return channel via satellite (DVB-RCS) networks. The proposed protocol sets TCP Congestion Window (CWND) size by using satellite resource allocation information exchanged between TCP and the link-layer. we implement PEP testbed based on Linux to evaluate the performance of the proposed protocol. The simulation results show that the proposed protocol performs better than standard TCP both in single and multiple sessions in variant BER, because the proposed protocol sets TCP CWND size by using satellite resource allocation.

Non binary turbo codes are gaining a lot of attention since the recent adoption of duo binary circular turbo codes by the Digital Video Broadcasting (DVB) community. In this paper, a Joint Source Channel Decoding (JSCD) scheme is proposed for circular non-binary turbo codes. With a view to exploit a-priori probabilities from source statistics, a symbol level trellis is incorporated into the circular trellis of the non-binary turbo decoder. Reversible Variable Length Codes (RVLC) are used as the input source in all simulations. Results show that with JSCD, circular duo binary turbo codes provide an average gain of 0.4 dB at Bit Error Rate (BER) of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> as compared to conventional decoding of circular duo binary turbo codes. With circular triple binary turbo codes, JSCD provides a striking average gain of 3.5 dB at a BER of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> compared to conventional decoding of circular triple binary turbo codes.

In this paper an approach for joint source-channel coding in a spatio-temporal wavelet-based scalable coding environment is presented. The scalable quality layers are protected using a double binary turbo code for robust scalable transmission over wireless channels. In the proposed schema the double binary turbo code is used for bitstream adaptation with unequal error protection. An efficient method to estimate the minimum distance of the double binary turbo codes is also proposed. Experimental results show promising performance of the proposed model as compared to equal error protection at low signal to noise ratio.

Turbo codes (TC) is a powerful branch of error-control coding that has exhibited performances close to the Shannon limit, whilst offering a reasonable level of computational complexity. Repeat-punctured turbo codes (RPTCs) exploit the fact that the use of larger interleavers correspond to better bit-error rate (BER) performances for the conventional turbo code, and makes use of repetition and puncturing to improve the performance of the conventional turbo code for moderate to high signal-to-noise ratios (SNRs). Motivated by turbo codes and repeat-punctured turbo codes, we study the use of a new scheme, dual-repeat-punctured turbo codes (DRPTC) in the additive white Gaussian noise (AWGN) channel. DRPTCs primarily make use of repetition and puncturing and the structure of the conventional turbo code to yield a more superior performance. The decoding in principle follows the technique of turbo decoding but needs some changes to yield the performance improvement. Simulation results for the AWGN channel is presented together with the analytical union bounds derived from transfer-function bounding techniques, and the codeword distance-spectrum for the proposed scheme is presented and evaluated.

This paper introduces an advanced E-education provision via space systems for Africa or any other regions in remote dispersed communities, such as rural, mining, agriculture, surveying, construction, tourism, military and etc. Based on the specific needs and requirements E-education implies significant broadband applications, interconnectivity, and timely and quality-assured content delivery of service. The E-education solutions of distance learning and training for remote and rural areas, which are beyond range of terrestrial and short distance wireless cellular facilities, cannot provide broadband access without space-enabled communication solutions, such as satellite constellations and Stratospheric Platform Systems (SPS) or High Altitude Platforms (HAP). This paper also discusses the integration challenges that are presented by combining space solutions for implementation E-education and learning in rural and mobile environments. Configuration of in-house development of all segments, installation of the scale-down Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) Hub (Gateway), Ground Network and Very Small Aperture Terminal (VSAT), known as Fixed Interactive Terminals (FIT), for E-education, distance learning and staff training initiative in Africa are described.

For space-time bit-interleaved coded modulation (ST-BICM) systems with iterative decoding, the overall perfor- mance is affected by the chosen mapping. In bit error rate (BER) curves, one mapping reaches an error floor at a low signal- to-noise ratio (SNR), while other mappings result in a lower error floor at a higher SNR. The constellation mappings are divided into groups where each group exhibits a distinctive BER curve. We show that the convergence abscissa of the system depends on the average total bit errors and the harmonic mean of the minimum squared Euclidean distance. In this paper, we characterize all mapping groups for ST-BICM with 8PSK and present the optimal selection for each mapping group over independent fading channels. I. INTRODUCTION Space-time coding techniques significantly improve trans- mission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation with iterative decoding (BICM-ID) gives good diversity gains and Euclidean distance property with higher order modulation schemes using well known binary convolutional codes (1). Tonello (2) combined these two schemes as space-time BICM (ST-BICM) with Gray mapping. In this paper, we will first show that the asymptotic BER performance of ST-BICM system is equivalent to the single antenna BICM-ID case even when the throughput of ST-BICM is higher. This indicates that the total data rate of ST-BICM can be increased linearly with the number of transmit antennas while maintaining the same error probability as BICM-ID. This demonstrates the superior performance of ST-BICM. Motivated by the fact that the ST-BICM performance can be characterized by BICM-ID with the same code and mapping, we optimize the ST-BICM mappings based on the BICM-ID parameters. While the error floor (EF) bound (1) offers a good match for an error floor region, a heuristic analysis is still needed to study BER curve behaviors of BICM-ID for the water fall region. Thus, we derive design considerations based on both

The fifth-generation (5G) wireless communication system promises to revolutionize global connectivity by offering ultra-high-speed data transfer, massive device connectivity, and low latency. However, achieving these objectives demands efficient spectrum allocation and error-correcting mechanisms. The scarcity of radio spectrum and interference management are key challenges, necessitating optimized solutions for spectrum allocation. Additionally, reliable communication over noisy channels requires robust error-correcting codes. Optimized turbo codes, known for their iterative decoding capabilities, have emerged as a viable solution to enhance error resilience and throughput in 5G networks. This research proposes an integrated approach to optimize spectrum allocation and turbo code performance. The spectrum allocation employs a dynamic multi-objective optimization model based on machine learning algorithms, prioritizing fairness, quality of service (QoS), and interference minimization. Simultaneously, an improved turbo coding algorithm utilizing adaptive puncturing and interleaving strategies enhances data integrity. Simulations conducted in a heterogeneous 5G environment demonstrate significant performance improvements. The optimized turbo codes achieve a Bit Error Rate (BER) of 10-5 at a Signal-to-Noise Ratio (SNR) of 2.5 dB, outperforming conventional turbo codes by 40%. The proposed spectrum allocation strategy enhances spectral efficiency by 25%, ensuring equitable resource distribution and improved QoS. This integrated framework highlights the potential for scalable and efficient 5G systems, addressing the dual challenges of spectrum scarcity and error correction.

A new rate 1/2 turbo code with short memory 2 is developed in this paper. The proposed turbo code consists of two 4-state parallel concatenated non-punctured systematic rate-2/3 convolutional codes. Using a modified maximum a posteriori (MAP) decoding algorithm working on dual codes, its bit error rate (BER) performance is comparable to that of the classic 16-state turbo code at short block lengths, such as k=1024, while its decoding complexity is less than 1/8 that of the classic 16-state turbo codes; for information block length k=504, its BER performance is better than that of the (1008, 3, 6) LDPC codes with comparable decoding complexity. The dual code decoding algorithm is intrinsically partial parallel and a considerably higher throughput of the turbo decoder can be obtained compared with classic turbo codes consisting of punctured codes. The simulation results show that the proposed turbo code can be a competitive technique for short block length applications.

In order to pursue rapid development of the new generation of wireless communication systems and elevate their security and efficiency, this paper proposes a novel scheme for automatic dual determination of modulation types and signal to noise ratios (SNR) for next generations of wireless communication systems, fifth-generation (5G) and beyond. The proposed scheme adopts unique signatures depicted in two-dimensional asynchronously sampled in-phase-quadrature amplitudes' histograms (2D-ASIQHs)-based images and applies the support vector machines (SVMs) tool. Along with the estimation of the instantaneous SNR values over 0-35 dB range, the determination of nine modulation types that belong to different modulation categories i.e., phase-shift keying (Binary-PSK, Quadrature-PSK, and 8-PSK), amplitude-shift keying (2-ASK and 4-ASK) and quadrature-amplitude modulation (4-QAM, 16-QAM, 32-QAM, and 64-QAM) could be achieved by this scheme. The application of this scheme has been simulated using a channel model that is impaired by additive white Gaussian noise (AWGN) and Rayleigh fading, covering a broad range of SNRs of 0-35 dB. The performance of this dual-determination scheme shows high modulation recognition accuracy and low mean SNR estimation error. Therefore, it can be a better alternative for designers of next generation wireless communication systems.

The Transmit antenna selection (TAS) technique is essential to increase the efficiency of spatial modulation (SM) systems. This TAS is an effective technique for reducing the Multiple Input Multiple Output (MIMO) systems, which can increase the computational difficulty and Bit error rate (BER) by various TAS algorithms. But these selection methods cannot provide code gain, so it is essential to join the external code in TAS to obtain code gain advantages in BER. In some existing work, the improved BER has been perceived by joining Forward Error Correction Code (FEC) and Space Time Block Code (STBC) for MIMO systems provided greater code gain. A multiple TAS-OSTBC technique with new integration of Bose–Chaudhuri–Hocquenghem (BCH)-Turbo code (TC) is proposed in this paper. The TAS-OSTBC system connects with the external BCH code in sequence of internal Turbo code. This combination can provide increasing code gain and the effective advantages of the TAS-OSTBC system. To perform the system analysis Rayleigh channel is utilized. In the case with multiple TAS-OSTBC systems, better performance can provide by this new combination of the BCH-Turbo compared to the conventional Turbo code for the Rayleigh fading.

We define super codes as the serial concatenation of punctured convolutional codes. Puncturing pattern and interleaver design techniques are presented so as to maximise the free distance of the code and thus the performance at very low bit error rates (BER). The performance of super codes is compared to turbo codes. For BERs around 10/sup -5/, turbo codes perform 0.1, 0.4 and 0.6 dB better than super codes for rates 3/4, 1/2 and 1/3, respectively. However, due to the use of serial concatenation, super codes have an interleaver gain of N/sup -2/, compared to only N/sup -1/ for turbo codes and interleaver size N. Thus, super codes are expected to perform significantly better at BERs around 10/sup -10/.

A novel method to combine encryption and channel coding in such a way as to get increased security without any additional complexity is presented in this paper. A secure communication system usually consists of an encryption block followed by the channel coder. The encryption block here is a Shrinking generator which is a Linear Feedback Shift Register (LFSR) based stream cipher system. The channel coding technique used is Turbo codes or Low Density Parity Check Codes (LDPC) that performs very well and provides results near Shannon's Limit. Controlled randomness using Pseudo Random Bit Sequence (PRBS) generator is incorporated during encoding of these codes to provide additional level of security in the system without any additional complexity. To achieve optimum decoding, soft decision decoding algorithms are used rather than hard decisions. Bit Error Rate (BER) performance of the proposed channel coders with keyed randomness is well analyzed for intended and un-intended users. Security of the system is analyzed by mounting Improved Linear Consistency Attack and the results show that a significant increase in security is achieved in a stream cipher based secure communication system without any additional increase in complexity by introducing security in channel coding.

We present an algorithm that allows two users to establish a symmetric cryptographic key by incorporating the most important features of the wireless channel in vehicle-to-vehicle (V2V) communication. Non-reciprocity compensation is combined with turbo codes (TCs) for error reconciliation purposes. For fair comparisons, the indexing technique is applied in conjunction with the non-reciprocity compensation technique. A series of simulations are run to calculate key performance indicators (KPIs). High entropy values are obtained throughout all rounds of simulation during the key extraction process. Furthermore, simulation results indicate a significant improvement in bit mismatch rate (BMR) and key generation rate (KGR) when TCs are used. Increasing the number of iterations in the TC can significantly improve the Bit Error Rate (BER), thus generating more symmetric keys. The key generation rate was reported high ranging from 17 to 19 for the 256-bit symmetric keys per minute with TCs, while it is ranging from 2 to 5 when compared with a sample indexing technique published in the public domain. Finally, simulations proved also improvements for different key lengths as part of the error reconciliation process when TCs are used with an almost regular permutation (ARP) instead of a random permutation.

Turbo codes are at present standardised for digital video broadcasting (DVB-RCS) where interleavers are defined with four parameters. A new parameter-selecting strategy is introduced to improve DVB-RCS turbo codes. The performance of DVB-RCS standard codes is compared with that of turbo codes having the newly selected parameters. Computer simulations show the improvement of turbo codes with the new interleaver parameters.

Orthogonal Frequency Division Multiplexing (OFDM) has been considered as a strong candidate for next generation wireless communication systems. Compared to traditional OFDM, Single Carrier OFDM (SC-OFDM) has demonstrated excellent bit error rate (BER) performance, as well as low peak to average power ratio (PAPR). Similar to other multi-carrier transmission technologies, SC-OFDM suffers significant performance degradation resulting from intercarrier interference (ICI) in high mobility environments. Existing techniques for OFDM can be directly adopted in SC-OFDM to improve performance, however, this improved performance comes at costs such as decreased throughput. In this paper, we analyze the effect of ICI on an SC-OFDM system and propose a novel modulation scheme. The proposed Magnitude-Keyed Modulation (MKM) modulation provides SC-OFDM system immunity to ICI and with an easy implementation it significantly outperforms OFDM, SC-OFDM and MC-CDMA systems with Phase Shift Keying (PSK) modulation and Quadrature Amplitude Modulation (QAM) in severe ICI environment. Analysis also illustrates the proposed SC-OFDM system with MKM modulation maintains low PAPR compared to traditional OFDM and SC-OFDM systems with PSK and QAM modulations. Simulation results for different modulation schemes in various ICI environments confirm the effectiveness of the proposed system.