Energy efficient channel coding based on position awareness and radio link budget estimation

A wireless packet data communications system that uses adaptive channel coding on the radio link is studied. A channel coding adaptation mechanism based on recommendation from the receiver is proposed. A traffic model that exhibits self-similarity is considered for packet data applications. The radio channel is modeled as a Rayleigh fading channel. The performance of TCP over such an adaptive radio link is obtained through analysis and simulation. The result indicates significant improvement in throughput and delay performance for TCP over adaptive packet radio link. To gain insight to dimensioning of wireless packet networks. TCP throughput and delay are studied with respect to the number of users and file size. System utilization is analyzed and theoretical bounds are derived and compared with simulation results.

Fountain coding is a valuable tool for multicast transmissions in half-duplex packet radio networks if it is supported by an adaptive transmission protocol that compensates for fluctuations in the propagation losses on the radio links. Our goal is to devise low-complexity packet-by-packet adaptive modulation and channel coding protocols that provide high throughput for a broad range of multicast channels and operate with limited feedback and no knowledge of the fade levels or even the probability distribution for the fading on the radio links. The only control information for the protocols is derived from simple receiver statistics that are obtained by the demodulators and channel decoders in the receiving radios. Performance results are presented for practical fountain coding with low-complexity adaptive modulation and channel coding. Results on ideal fountain coding with adaptive transmission based on hypothetical perfect channel-state information are employed as performance benchmarks.

The development of in‐vivo communications and networking systems has the potential for improving the healthcare delivery while also enabling the creation of new services and applications. In‐vivo communications provide wireless networked cyber‐physical systems of the embedded devices that enable accurate, quick, and cost‐effective responses under a variety of circumstances. Also, it is focused upon modeling and characterizing in‐vivo wireless channel, as well as contrasting it to other well‐known channels. In this paper, channel coding is also mentioned because it improves data rates and performance gain. This work also discusses present problems and potential research topics for in‐vivo communications. This article aims to show the researchers how the orthogonal frequency multiple access (OFDMA) technique improved the performance of in‐vivo channel and how it is outperformed compared to the other techniques (TDM, TDMA, CDMA and OFDM) also how the OFDMA outperformed equalizers and channel coding in terms of bit error rate with giving a significant improvement of data transmitting and avoiding inter symbol interference. However, when it comes to the in‐vivo communications, the modeling of in‐vivo wireless channel is vital. Understanding the features of the in‐vivo channel is critical for achieving optimal processing and designing successful procedures that allow WBANs to be arranged inside the human body.

In this work, we are interested in implementing, developing, and evaluating a time reversal strategy for a multiple-input single-output orthogonal frequency division multiplexing system. This strategy enjoys a good trade-off between the computational complexity and performance in terms of bit error rate where it offers a good coding gain by forming a beam in the direction of the destination at a price of channel state information available at the transmitter. In time reversal technique, a higher coding and diversity gain can be achieved by increasing the number of transmitting antennas, which focuses the formed beam to the direction of the destination antenna. By achieving this, the received signal-to-noise ratio can be maximized which makes time reversal a good candidate for multiple-input single-output systems while keeping a low complexity. The performance of the proposed system is evaluated in terms of bit error rate where our simulations show that the proposed strategy enjoys the full diversity gain, which is equal to the number of transmitting antennas. Moreover, a robust channel estimation technique is proposed to improve the overall system in terms of bit error rate.

Orthogonal frequency division multiplexing (OFDM) is a type of digital modulation technique which is used in wireless communication systems. It is an efficient multicarrier modulation technique, in which large bandwidth is divided into parallel narrow bands each of which is modulated by different subcarriers. All the subcarriers are orthogonal to each other and hence it reduces the interference among various subcarriers. But OFDM suffers from high peak to average power ratio(PAPR), high complexity in design. The performance parameter of OFDM can be measured in terms of Bit error rate (BER). Lower the BER value, higher is the efficiency of OFDM system. Various methods are used to enhance the BER performance. Channel coding is the one way of enhancing the BER. This paper discusses the performance of OFDM using linear & cyclic block coding for different digital modulation techniques. Bit error rate (BER) is used to measure the performance of OFDM systems.

Channel coding is a fundamental procedure in wireless telecommunication systems and has a strong impact on the data transmission quality. This effect becomes more important when the transmission must be characterised by low latency and low bit error rate, as in the case of vehicle-to-everything (V2X) services. Thus, V2X services must use powerful and efficient coding schemes. In this paper, we thoroughly examine the performance of the most important channel coding schemes in V2X services. More specifically, the impact of use of 4th-Generation Long-Term Evolution (4G-LTE) turbo codes, 5th-Generation New Radio (5G-NR) polar codes and low-density parity-check codes (LDPC) in V2X communication systems is researched. For this purpose, we employ stochastic propagation models that simulate the cases of line of sight (LOS), non-line of sight (NLOS) and line of sight with vehicle blockage (NLOSv) communication. Different communication scenarios are investigated in urban and highway environments using the 3rd-Generation Partnership Project (3GPP) parameters for the stochastic models. Based on these propagation models, we investigate the performance of the communication channels in terms of bit error rate (BER) and frame error rate (FER) performance for different levels of signal to noise ratio (SNR) for all the aforementioned coding schemes and three small V2X-compatible data frames. Our analysis shows that turbo-based coding schemes have superior BER and FER performance than 5G coding schemes for the vast majority of the considered simulation scenarios. This fact, combined with the low-complexity requirements of turbo schemes for small data frames, makes them more suitable for small-frame 5G V2X services.

Transmission efficiency, defined as the ratio of successfully transmitted information bits to overall bits transmitted, can be used for evaluating the transmission performance of wireless links. As a function of received signal to noise ratio (SNR), transmission efficiency is determined by physical layer technologies, such as channel coding, interleaving, modulation and other error-recovery techniques of wireless links. In this paper we first analyze the form of transmission efficiency function in wireless links, then based on that we propose an adaptive coding scheme that maximizes the transmission efficiency according to wireless channel conditions (received SNR). Simulation results show that with the proposed adaptive coding, transmission efficiency of wireless links can be significantly enhanced.

It has been previously shown that communications in tunnel environments can be improved by using multiple-input-multiple-output (MIMO) techniques, despite the small angular spread of the rays. However, narrowband transmission was always assumed to fulfill the flat channel hypothesis. The objective of this letter is to generalize these previous works to the case of a wideband communication, i.e., when the transmission bandwidth is much larger than the coherence bandwidth of the channel. Performances of MIMO combined with orthogonal frequency division multiplexing (MIMO-OFDM) are studied in terms of bit error rate and considering either space-time coding or spatial multiplexing. Transfer matrices of the channel measured in a straight arched tunnel are introduced in the software used for simulating the communication link.

Wavelet-OFDM based on the discrete wavelet transform, has received a considerable attention in the scientific community, because of certain promising characteristics. In this paper, we compare the performance of Wavelet-OFDM based on Meyer wavelet, and OFDM in terms of peak-to-average power ratio (PAPR), bit error rate (BER) for different channels and different equalizers, complexity of implementation, and power spectral density. The simulation results show that, without decreasing the bandwidth efficiency, the proposed scheme based on Meyer Wavelet-OFDM, outperforms OFDM in terms of PAPR by up to 4.5 dB, and in terms of BER by up to 6.5 dB of signal to noise ratio when using the minimum mean-square error equalizer without channel coding, at the cost of a computational complexity increase.

The ever-growing numbers of medical digital images and the need to share them among specialists and hospitals for better and more accurate diagnosis require that patients' privacy be protected. During the transmission of medical images between hospitals or specialists through the network, the main priority is to protect a patient's documents against any act of tampering by unauthorised individuals. Because of this, there is a need for medical image authentication scheme to enable proper diagnosis on patient. In addition, medical images are also susceptible to salt and pepper impulse noise through the transmission in communication channels. This noise may also be intentionally used by the invaders to corrupt the embedded watermarks inside the medical images. A common drawback of existing watermarking methods is their weakness against salt and pepper noise. The research carried out in this work addresses the issue of designing a new watermarking method that can withstand high density of salt and pepper noise for brain MRI images. For this purpose, combination of a spatial domain watermarking method, channel coding and noise filtering schemes are used. The region of non-interest (RONI) of MRI images from five different databases are used as embedding area and electronic patient record (EPR) is considered as embedded data. The quality of watermarked image is evaluated using Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity Index (SSIM), and the accuracy of the extracted watermark is assessed in terms of Bit Error Rate (BER).

Recently, a cooperative communication technique called coded cooperation is presented. The cooperation in this method is performed by way of channel coding as a substitute for a direct relay or repetition. In a multi-user environment, more than one single antenna mobiles cooperate in virtual MIMO system to accomplish transmit diversity while supporting the same information rate and transmission power. Concatenated Reed Solomon and convolutional codes, RSCC, are effective channel codes to reduce the noise. So they have been employed by some wireless communication standards such as IEEE 802.16e WiMAX. In this paper, we compare the performance of RSCC, concatenated codes, coded cooperation to RS, codes without concatenation, coded cooperation in terms of bit error rate with various SNR and Doppler shift values utilizing higher order modulation techniques. We adopt the structure of physical layer specifications of IEEE 802.16e WiMAX. The results illustrate the performance of RSCC coded cooperation as compared to RS coded cooperation is significantly supreme at medium and high SNR ranges and at low and medium Doppler shift ranges. The results show RSCC coded cooperation is robust for a high transmission rate operation as well.

The performance of orthogonal frequency division multiplexing- (OFDM-) based free-space optics (FSO) depends on various parameters such as number of subcarriers, base band modulation, nature of laser beam, turbulence modelling, and much more. Various diversity techniques have been studied by researchers for the improvement of signal strength due to fading caused by atmospheric turbulence. In this paper, a novel channel coding scheme formed by serially concatenation of irregular low-density parity check (LDPC) and trellis code modulation (TCM) codes linked by interleaver is proposed. The proposed unified coding scheme is simulated and analyzed using the lognormal scintillation model, which is suitable for weak turbulent conditions. The obtained results are the comparative study of various channel coding schemes in terms of bit error rate (BER) vs. signal-to-noise ratio (SNR). Simulation results confirm that newly designed hybrid code outperforms the independently coded and uncoded systems under weak turbulence conditions by reducing the number of errors in the transmitted information that occurs due to fading. It is found that the presented hybrid coded OFDM-FSO system with 16-level quadrature amplitude modulation (QAM) provides significant improvement with less decoding complexity and reasonable delay.

This paper presents some results on MMSE turbo equalization applied to real sea water trials in the Atlantic ocean. High order modulations (8-PSK, 16-QAM and 32-QAM) have been tested. The channel data rate on the underwater acoustic channel is up to 20 kbps. The receiver includes timing recovery, equalization, interleaving and channel coding. The results which are evaluated in term of bit error rate (BER) and mean square error (MSE) show that turbo equalization improves the performance of the receiver and allows reliable high order transmissions when the signal to noise ratio is sufficient.

Spectrum sensing (SS) is the key enabling technology for wideband cognitive radio networks, where two coexisting systems share the same frequency band. The critical task of SS is required to detect spectrum opportunities and to determine if the spectrum allocation meets the quality of service (QoS) requirements of different users. In case of missed detection, collision happens between secondary and primary users. This causes erasures along the secondary user bit stream and a fraction of data is lost. Since the sensing time determines network responsiveness and performance, it is desired to maintain this parameter reduced as possible. But this can be at the expense of increasing collision probability. Thus, the secondary receiver can employ coding to counter the effect of erasures, according to desired sensing time. In this paper, we design new decoding scheme based on BCH codes to compensate for the decrease in sensing time. Simulations were carried out and the results show that our technique exhibits better performance in terms of bit error rate (BER) for high achievable rates, while keeping the sensing time at lower level.

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