Uplink millimeter-wave multi-cell multi-user massive multi-input multi-output systems

In this paper author demonstrates the relationship between spectral efficiency and energy efficiency for 10 Gbps, 40 Gbps and 100 Gbps transmission systems with NRZ-OOK, NRZ-DPSK and DP-QPSK modulation formats respectively. The focus of this research is the wavelength division multiplexed (WDM) transmission systems with Forward Error Correction (FEC) technology with required Bit Error Rate (BER) level that does not exceed 10−3. For this purpose the signal BER level versus cross-channel interval response is evaluated. Obtained data was used for the regeneration length calculations with purpose to define the number of regeneration steps for 200km and 2600km transmission systems. In order to observe relationship between spectral and energy efficiency, power consumption was calculated using different crosschannel intervals −37.5 GHz, 50 GHz and 100 GHz, by means of what different spectral efficiencies were reached. The total power consumption of transmission system was calculated by defining the quantity and power consumption values for all WDM system elements that require electrical energy. In this paper author demonstrates how the amount of transmitted information influence the total system power consumption in each considered transmission system and by using obtained data and spectral efficiency data, the systems energy efficiencies were calculated.

The Internet of Things (IoT) and machine-to-machine (M2M) communication will play an important role in future communications, but there is currently no ultra-reliable low-latency wireless communication theory that guides its design. For highly mobile vehicle-to-vehicle (V2V) wireless communication scenarios, asynchronous transmission should also be accepted. Therefore, it is particularly urgent to study ultra-reliable low-latency wireless transmission technology that satisfies asynchronous transmission. Universal Filter Multi-Carrier (UFMC) is a new type of filtering wireless transmission mechanism that meets this character. Although some of its properties have been explored in recent years, there are few articles that systematically evaluate its performance. In this paper, firstly, the performance of the UFMC system is fully evaluated in terms of spectral efficiency (SE), bit error rate (BER), peak-to-average power ratio (PAPR), carrier frequency offset (CFO), as well as various multipath fading channels, effects of time delay (TD), etc. Meanwhile, a mathematical analysis model is established for the BER of UFMC system, and some exact closed-loop expressions of bit error probabilities for UFMC are derived. Moreover, the equivalent form of the transmitter in the frequency domain is derived. Finally, the Monte Carlo simulation results related to UFMC are presented. The results reveal that UFMC suffers from the same problems as other multi-carrier system, including higher PAPR, affected by CFO, but it has its own inherent advantages such as insensitivity to time delay or energy-efficient, and the main negative factor of UFMC is inter-carrier interference (ICI) not inter-symbol interference (ISI), which may play an important role in future M2M and V2V communication.

The purpose of this paper is to provide a detailed description and experimental and simulated performance results for some of the current Raytheon satcom high efficiency tactical waveforms, namely the dual-h quaternary continuous phase modulated (CPM) waveforms and the shaped phase shift keying (SPSK) waveforms. The emphasis is on the performance in terms of adjacent channel interference (ACI), bit error rate (BER), coding gain over conventional waveforms, and the ability of the radio to acquire these waveforms while being subjected to a Doppler frequency of /spl plusmn/1200 Hz. This paper first introduces the mathematical representation of the dual-h quaternary CPM waveform. Then the principle of the data demodulation including carrier and symbol timing acquisition and tracking using the MIL-STD-188-181B-specified preamble is illustrated. Finally, with the use of computer simulations, the spectral envelope and bandwidth efficiency of these efficient waveforms are compared to conventional counterparts.

Massive multiple-input multiple-output (massive MIMO) and the millimeter wave (mmWave) communication are known to be among the key technologies for the fifth generation (5G) mobile networks. The implementation of massive MIMO with the mmWave architecture requires the utilization of hybrid precoding technique with a low dimensional digital precoder and a high dimensional analog precoder. In this paper, we investigate the hybrid precoding design problem for the case of cooperative multicell multiuser massive MIMO system. This problem is formulated with the consideration of the user and base station (BS) association problem, and we propose an iterative algorithm to solve the formulated problem. The precoding problem is solved using the Eigen precoding algorithm whereas the Lagrangian based approach is proposed for the solution of the association problem. Simulation results show that our proposed solution can achieve higher energy efficiency and convergence rate.

In this paper, we assess the performance of a generalized frequency division multiplexing (GFDM) transceiver for underwater acoustic high data-rate transmission. We also present a comprehensive overview of the work done in the field of next generation multicarrier techniques beyond orthogonal frequency division multiplexing (OFDM) for underwater acoustic (UWA) channels. Since very little work has been done in determining the feasibility of acoustic GFDM, we evaluate the performance of proposed GFDM transceiver in terms of spectral efficiency, peak to average power ratio, error rates and complexity using simulations. We employ two types of receivers - matched filter and zero forcing and evaluate their performances for several system configurations. Results presented show that the zero forcing receiver outperforms the matched filter receiver at high SNR values for almost all the configurations; exceptions being the cases where 1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> and 4 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> Xia pulse shapes are employed with higher values of the roll off factor. We also compare the performance of the proposed GFDM transceiver with that of OFDM and show that GFDM outperforms OFDM by almost 4 dB for a symbol error rate of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> . It is concluded that while GFDM is computationally more demanding than OFDM, it is still an appealing technique for future UWA communications due to its higher spectral efficiency, flexibility, and better error performance.

On the performance of SIC-free spatial modulation aided uplink NOMA under imperfect CSI

Orthogonal frequency-division multiplexing (OFDM) can achieve remarkable performance in terms of spectral efficiency, but its power amplifier efficiency becomes poor because of its high peak-to-average power ratio (PAPR) nature of transmitted signals. Trellis shaping is an effective method to reduce peak and average power without signal distortion at the cost of transmitter complexity and its performance depends on the metric used for the trellis decoder. Several metrics, defined in either time or frequency domain, have been proposed in the literature. In many practical OFDM systems, however, slight nonlinearity is tolerable as long as the resulting distortion meets the system requirements such as bit error rate (BER) and spurious level of transmitted signals. In this paper, we make a thorough performance comparison of trellis-shaped uncoded OFDM systems with different metrics in terms of complexity, achievable PAPR, and resulting BER as well as power spectrum in a practical channel where the signal envelope is distorted by a power amplifier (PA). Our study shows that the metric designed in frequency domain is mostly favorable in such a scenario.

Light fidelity (Li-Fi) systems based on the orthogonal frequency division multiplexing (OFDM) scheme have gained more attention in the communications circles, as a means to provide high spectral efficiency and ensure stricter data rate requirements for visible light communication (VLC) systems. However, common OFDM schemes employ Hermitian symmetry to obtain a real-valued signal which is necessary in intensity modulation and direct detection (IM/DD) optical systems, at the expense of doubling the required bandwidth. In this paper, a novel transmission scheme for an OFDM-based Li-Fi system is proposed to tackle the issue in question. A new approach to complex signal mapping (CSM), based on the pairing function method, has been developed for Li-Fi systems. It does not require Hermitian symmetry and, hence, saves about 50% of the required bandwidth. Unlike existing OFDM-based VLC approaches, the proposed scheme employs CSM to ensure a real and positive signal without Hermitian symmetry in order to fully utilize the bandwidth available to Li-Fi networks. Simulation results show that the proposed scheme significantly outperforms other systems in terms of spectral efficiency. The CSM-OFDM based Li-Fi system also achieves a good peak-to-average power ratio (PAPR) reduction with acceptable bit-error-rate (BER) performance, compared to conventional approaches.

Recently, technological developments have enhanced, the use of Millimeter-wave (mm-Wave) Multiple Input Multiple Output (MIMO) system in various communication applications and wireless sensor networks as channel estimation efficiency can be immensely improved with the help of this technological developments in Millimeter-wave MIMO system and wireless sensor network as well. Moreover, they can improve quality of communication services to a great extent. However, cell interference in Millimeter-wave (mm-Wave) MIMO system can produce a massive impact on spectral efficiency. Therefore, a Routing Enabled Channel Estimation (RECE) technique is presented in this article to minimize interference between cells. The proposed Channel Estimation technique improves channel capacity as well as spectral efficiency. Moreover, Normalized Mean Square Error (NMSE) is minimized heavily using proposed RECE technique. Here, main aim of this article is to reduce cell interference and channel estimation inside a cell by using route selection, beam selection, and spatial frequency estimation. Here, different scenarios and parameters are considered to evaluate performance efficiency of proposed RECE technique in terms of spectral efficiency, NMSE and SNR and compared against varied traditional channel estimation techniques. Moreover, it is clearly evident from performance results that the proposed channel estimation technique performs better than the other two methods.

Adaptive orthogonal frequency division multiplexing (OFDM) has been shown to have significant improvement over basic OFDM in terms of spectral efficiency and bit error rate performance. However, the most important condition to achieve these benefits is the availability of accurate channel state information (CSI) at the transmitter. Imperfect CSI arises from noise at the receiver and due to a delay in providing the CSI from the receiver to the transmitter for the next data transmission. In this paper, we have studied the impact of imperfect CSI on the spectral efficiency of adaptive OFDM systems. We have proposed a robust loading algorithm to improve the performance of such systems. This algorithm applies the bit under loading phenomenon and makes efficient use of M-ary Phase Shift Keying (MPSK) modulation. Plots of spectral efficiency via simulations are provided.

Modulation techniques in 5G wireless communication systems play a crucial role in meeting demands for higher data rates, lower latency, and improved connectivity. This involves optimizing power spectral density (PSD), enhancing data transmission reliability, and reducing bit error rates (BER) and interference. The objective of this paper is to evaluate primary modulation schemes used in 5G—Orthogonal Frequency Division Multiplexing (OFDM), Filter-Orthogonal Frequency Division Multiplexing (F-OFDM), Filter Bank Multi-Carrier (FBMC), and Universal Filtered Multi-Carrier (UFMC)—based on performance metrics such as PSD, BER, and signal-to-noise ratio (SNR) using MATLAB. OFDM demonstrates low BER at high SNR but faces degradation at lower SNRs, necessitating a higher SNR for maintaining low BER. F-OFDM improves BER in noisy environments through reduced out-of-band emissions and improved spectral efficiency. FBMC shows lower BER than OFDM, especially in multipath fading scenarios, despite its higher complexity. UFMC provides balanced performance with moderate BER across varying SNRs, offering a trade-off between simplicity and efficiency, with stable BER and enhanced spectral efficiency, and reduced latency compared to OFDM. Each modulation scheme in 5G presents specific strengths and weaknesses. OFDM is robust and widely used, while F-OFDM, FBMC, and UFMC enhance spectral efficiency, BER, and SNR management. Selecting the appropriate technique depends on network requirements, with MATLAB simulations playing a crucial role in optimizing 5G network performance.

A plethora of new applications will be enabled by next generation wireless networks. These demand sophisticated medium access control and physical layer protocols in order to fulfill the requirements in terms of spectral efficiency, bit error rate (BER), energy efficiency, reliability, and security, among others. This paper develops an advanced space-time multiple-input, multiple-output (MIMO) solution that builds on the concept of space-time shift keying (STSK) for single-carrier frequency domain equalization (SC-FDE). STSK-aided SC-FDE, or SSF, ensures space-time and frequency diversity in dispersive channels, but can only support suboptimal linear receiver schemes. We therefore introduce a turbo equalizer for SSF in frequency-selective multipath channels. It enables inter-symbol-interference cancellation by means of iterative space-time processing. We coin it the iterative space-time block equalizer (SSF-ISTBE). We provide the mathematical formulation for the proposed SSF-ISTBE framework in non-linear channel conditions. We demonstrate that the SSF-ISTBE achieves a substantial 4 dB gain in terms of BER over the linear minimum mean square error equalizer while significantly reducing the computational complexity of the optimal maximum likelihood SSF. When considering practical transceivers, in particular non-linear power amplifiers, the gain of the SSF-ISTBE becomes more prominent over state-of-the-art approaches, demonstrating its robustness against non-linear distortion.

Universal Filtered Orthogonal Frequency Division Multiplexing (UF-OFDM) is one of the main candidate wave-form for the next generation of mobile communication due to its advantages in terms of spectral efficiency and the robustness against frequency offsets and Doppler spread. UF-OFDM suffers from the problem of having a high Peak to Average Power Ratio (PAPR) compared to conventional OFDM systems. Therefore, the development of efficient PAPR reduction methods is crucial. In this paper, we apply the Partial Transmit Sequence (PTS) method to reduce the PAPR in UF-OFDM systems as it does not suffer from spectral regrowth; also it does not impact the Bit Error Rate (BER). Due to the computational complexity of PTS, the Harmony Search Algorithm (HSA) is proposed where the proposed HSA will save about 84% of complexity compared with the conventional PTS. Moreover, a novel “adaptive HSA” technique is presented that gives the same performance as HSA with PTS while it saves about 48.3% in run time.

In the past decades, researchers/scientists have paid attention to the physical layer of underwater communications (UWCs) due to a variety of scientific, military, and civil tasks completed beneath water. This includes numerous activities critical for communication, such as survey and monitoring of oceans, rescue, and response to disasters under the sea. Till the end of the last decade, many review articles addressing the history and survey of UWC have been published which were mostly focused on underwater sensor networks (UWSN), routing protocols, and underwater optical communication (UWOC). This paper provides an overview of underwater acoustic (UWA) physical layer techniques including cyclic prefix orthogonal frequency division multiplexing (CP-OFDM), zero padding orthogonal frequency division multiplexing (ZP-OFDM), time-domain synchronization orthogonal frequency division multiplexing (TDS-OFDM), multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM), generalized frequency division multiplexing (GFDM), unfiltered orthogonal frequency division multiplexing (UF-OFDM), continuous phase modulation orthogonal frequency division multiplexing (CPM-OFDM), filter bank multicarrier (FBMC) modulation, MIMO, spatial modulation technologies (SMTs), and orthogonal frequency division multiplexing index modulation (OFDM-IM). Additionally, this paper provides a comprehensive review of UWA channel modeling problems and challenges, such as transmission loss, propagation delay, signal-to-noise ratio (SNR) and distance, multipath effect, ambient noise effect, delay spread, Doppler effect modeling, Doppler shift estimation. Further, modern technologies of the physical layer of UWC have been discussed. This study also discusses the different modulation technology in terms of spectral efficiency, computational complexity, date rate, bit error rate (BER), and energy efficiency along with their merits and demerits.

Adaptive M-QAM systems with maximal-ratio diversity (MRD) over composite arbitrarily correlated Nakagami-m fading and log-normal shadowing channels are analyzed. The slow adaptive modulation (SAM) technique is considered which adapts the constellation signaling to slow channel variations and achieves good performance in terms of spectral efficiency (SE) and bit error outage (BEO) despite its low feedback rate. Non-ideal channel estimation (CE) based on pilot symbols is assumed. Analytical expressions and tight bounds for the bit error probability are obtained which are used for deriving analytical expressions and tight bounds for the BEO and achieved SE (ASE). Performance evaluation results have shown that fading correlation and CE errors degrade the performance of SAM systems. The partition of resources for CE and information data requires a careful definition of the ASE and results have shown the tradeoff between CE quality and ASE.