Data Rate Enhancement Research Articles

Hybrid FSK–FDM Scheme for Data Rate Enhancement in Dual-Function Radar and Communication

In this paper, we present a hybrid frequency shift keying and frequency division multiplexing (i.e., FSK–FDM) approach for information embedding in dual-function radar and communication (DFRC) design to achieve an improved communication data rate. Since most of the existing works focus on merely two-bit transmission in each pulse repetition interval (PRI) using different amplitude modulation (AM)- and phased modulation (PM)-based techniques, this paper proposes a new technique that doubles the data rate by using a hybrid FSK–FDM technique. Note that the AM-based techniques are used when the communication receiver resides in the side lobe region of the radar. In contrast, the PM-based techniques perform better if the communication receiver is in the main lobe region. However, the proposed design facilitates the delivery of information bits to the communication receivers with an improved bit rate (BR) and bit error rate (BER) regardless of their locations in the radar’s main lobe or side lobe regions. That is, the proposed scheme enables information encoding according to the transmitted waveforms and frequencies using FSK modulation. Next, the modulated symbols are added together to achieve a double data rate using the FDM technique. Finally, each transmitted composite symbol contains multiple FSK-modulated symbols, resulting in an increased data rate for the communication receiver. Numerous simulation results are presented to validate the effectiveness of the proposed technique.

Performance assessment of OppNet routing protocols with real world mobility traces

A new paradigm has been introduced by researchers in the field of data accessing at several mobile positions through implementation of WAN instead of cellular telephony. Based on range/coverage and network topology WAN taxonomy has been categorized as fixed network, mobile access network and ad – hoc network/wireless mesh networks respectively. Several interesting challenges has been posed by researchers in wireless networks such as routing, bandwidth, congestion, security, quality of service (QoS) and data rate enhancement. Of late, researchers around the world have started working in the domain of SHiP (Sparse, Hybrid, Intermittent and Partitioned) Network, which are plagued by several characteristics features such as: sporadic connections, intermittent routing, store – carry – forward type of message forwarding mechanism, dynamic network topology, transitive closure of message transmission, fluctuating network link, bottleneck probability, trust, and security in social networks. In this paper an outline of Oppnet (Opportunistic Network), part of SHiP Network has been presented with as in-depth coverage of routing problems and research challenges in it. Additionally, taxonomy of Oppnet routing protocols is illustrated with the features on basis of which categorization has been done. An exhaustive investigation through implementation of well-known routing schemes like: Epidemic, Spray and Wait, PROPHET and Direct delivery against mobility models such as: Random Walk, Random Waypoint, Shortest path-based movement and Cluster Movement has been accomplished in open-source software: ONE simulator with real world mobility dataset and traces of city of New Delhi, capital of India. Results achieved have been good and exceed our expectations.

Transmit power control and data rate enhancement in cognitive radio network using computational intelligence

Underutilized radio frequencies are the chief apprehension in advance radio communication. The radio recourses are sparse and costly and their efficient allocation has become a challenge. Cognitive radio networks are the ray of hope. Cognitive radio networks use dynamic spectrum access technique to opportunistically retrieve and share the licensed spectrum. The licensed users are called primary users and the users that opportunistically access the licensed spectrum all called secondary users. The proposed system is a feedback system that work on demand and supply concept, in which secondary receivers senses the vacant spectrum and shares the information with the secondary transmitters. The secondary transmitters adjust their transmission parameters of transmit power and data rate in such a way that date rate is maximized. Two methods of spectrum access using frequency division multiple access (FDMA) and Time division multiple access (TDMA) are discussed. Interference temperature limit and maximum achievable capacity are the constraints that regulate the entire technique. The aim of the technique is to control the transmitter power according to the data requirements of each secondary user and optimizing the resources like bandwidth, transmit power using machine learning and feed forward back propagation deep neural networks making full use of the network capacity without hampering the operation of primary network.

A Comprehensive Study of Past, Present, and Future of Spectrum Sharing and Information Embedding Techniques in Joint Wireless Communication and Radar Systems

Wireless spectrum is a limited resource, and the rapid increase in demand for wireless communication-based services is increasing day by day. Hence, maintaining a good quality of service, high data rate, and reliability is the need of the day. Thus, we need to apportion the available spectrum in an efficient manner. Dual-Function Radar and Communication (DFRC) is an emerging field and bears vital importance for both civil and military applications for the last few years. Since hybridization of wireless communication and radar designs provoke diverse challenges, e.g., interference mitigation, secure mobile communication, improved bit error rate (BER), and data rate enhancement without compromising the radar performance, this paper reviews the state-of-the-art developments in the spectrum shared between mobile communication and radars in terms of coexistence, collaboration, cognition, and cooperation. Compared to the existing surveys, we explore an open research issue on radar and mobile communication operating with mutual benefits based on collaboration in terms of spectrum sharing. Additionally, this paper provides important perspectives for future research of DFRC technology.

Performance evaluation of a multicarrier MIMO system based on DFT-precoding and subcarrier mapping

The ever-increasing end user demands are instigating the development of innovative methods targeting not only data rate enhancement but additionally better service quality in each subsequent wireless communication standard. This quest to achieve higher data rates has compelled the next generation communication technologies to use multicarrier systems e.g. orthogonal frequency division multiplexing (OFDM), while also relying on the multiple-input multiple-output (MIMO) technology. This paper is focused on implementing a MIMO-OFDM system and on using various techniques to optimize it in terms of the bit-error rate performance. The test case considered is a system implementation constituting the enabling technologies for 4G and beyond communication systems. The bit-error rate optimizations considered are based on preceding the OFDM modulation step by Discrete Fourier Transform (DFT) while also considering various subcarrier mapping schemes. MATLAB-based simulation of a 2 ? 2 MIMO-OFDM system exhibits a maximum of 2 to 5 orders of magnitude reduction in bit-error rate due to DFT-precoding and subcarrier mapping respectively at high signal-to-noise ratio values in various environments. A 2-3dBs reduction in peak-to-average power ratio due to DFT-precoding in different environments is also exhibited in the various simulations.

Dual-Band Power Amplifier Design at 28/38 GHz for 5G New Radio Applications

This paper presents the design of a dual-band power amplifier (PA) featuring similar performance at 28 GHz and 38 GHz. In the new radio (NR) of the fifth generation (5G) communication system, the inter-band carrier aggregation technique is commonly adopted for data rate enhancement. In such configuration, operation at both bands of the 5G frequency range 2 (FR2) spectrum is often necessary. The stacked-FET topology was adopted for mitigation of the gain roll-off with frequency to achieve similar performance at both frequency bands. Implemented in the commercial 0.15-μm gallium arsenide (GaAs) pseudomorphic high electron mobility transistor (pHEMT) technology, the PA delivered a small signal gain of 18.5/18 dB, an output power at saturation (P_sat) of 28.5/28.2 dBm, and a peak power-added efficiency (PAE) of 39%/36% at 28/38 GHz, respectively. The measurement results have demonstrated great potential of the proposed PA for 5G NR applications.

Data rate enhancement of free space optical communication using pulse positioned differential phase shift keying.

In this paper, a pulse positioned-differential phase shift keying technique is proposed to enhance the data rate in free space optical communication. Using the schematics of polarization rotation differential phase shift keying, multi-rate functionality can be achieved without using delay-line interferometers. Furthermore, the proposed novel modulation format-differential phase shift keying combined with pulse-position modulation-enables a high data rate owing to the use of an average power limited amplifier. By using the average power limited amplifier, the signal power is increased as the pulse position order increases, which enhances the bit-error-rate performance. The increased signal power can be converted to an enhanced data rate. We demonstrated that the data rate above 625 Mbps can be increased in every step, as the pulse position order increases in the pulse positioned-differential phase shift keying. The performance enhancement of the proposed technique is theoretically and experimentally demonstrated.

Data Rate Enhancement of FSK Transmission Scheme for IEEE 802.15.4-Based Field Area Network

Due to the merits of simple implementation and low-power consumption, frequency shift keying (FSK) is widely used in wireless communication systems for the Internet of things (IoT) such as Wi-SUN field area network (Wi-SUN FAN). To expand IoT capacity or diversify IoT application scenarios, higher data rates are highly expected. In this paper, we propose a novel design of data rate enhancement for IEEE 802.15.4-based 2-FSK transmission scheme which meets the radio requirements defined by ARIB STD-T108 regulation in Japan. Fundamental evaluations and field experiments with developed integrated circuits (ICs) are conducted to evaluate the transmission performance of FSK with enhanced data rate parameters. Results show that with the ICs, the data rate of 600 kbps is achieved with a required input power increase of 7.0 dB compared with the conventional data rate of 100 kbps, and can achieve the packet error rate (PER) smaller than 10% for 250 m on line-of-sight (LoS) routes in urban environments. Moreover, the frequency interference level of the proposed FSK scheme is measured to evaluate the performance in practical radio conditions. Results provide reference for the channel management to operate FSK-based communication systems.

Theoretical and experimental optimization of DMT-based visible light communication under lighting constraints

High spectral efficiency is a key element that drives research for future wireless communication systems in order to meet the increasing demand for ubiquitous connectivity despite a limited radio frequency spectrum. Visible light communications (VLC) that allow exploiting the existing infrastructure for both lighting and communications could be an effective and economic solution. Thanks to the revolution in the field of solid-state lighting and the accelerated development of light-emitting diodes (LED), VLC becomes one of the most promising new technologies for the next generation of wireless communication systems. However, the limited bandwidth of the LEDs remains a major challenge that is limiting VLC from achieving very high data rates. In this paper, we propose to adapt the discrete multi-tone (DMT) modulation scheme of indoor VLC communications for data rate enhancement. With the help of bit and power-loading algorithms, a transmission bandwidth much larger than the 3-dB bandwidth of the LED could be exploited. We firstly present the typical lighting requirements for indoor applications and investigate the maximal bit-rate of DMT-based VLC. Then, with a regular luminance level for normal office work, an overall optimization of DMT configuration scheme in terms of modulated bandwidth, subcarrier number, cyclic prefix length, and clipping level is proposed. Theoretical analysis and verifications by experiments are simultaneously carried out. Based on the proposed configuration, we demonstrate a 100-Mbps VLC wireless transmission employing low-cost components under realistic lighting constraints.

A Theory for Optimizing Insecure Internetwork Connections

While internetwork connections among private and public networks are inevitable and essential for enhancing the data rate and range of communication among networks, they introduce new vulnerabilities and risks of security breach to the interconnected networks. In this article, a novel information-theoretic model is proposed to analyze the tradeoff between network security and data-rate enhancement considering homogeneous and heterogeneous internetwork connections between two networks. Various patterns of internetwork connections among gateway nodes are studied. The implications of internetwork connections on data manipulation due to security breach by attackers are investigated by modeling the internetwork connections as a noisy communication channel. Specifically, the fundamental limit of the maximum achievable capacity afforded by internetwork connections is characterized, while considering the impact of security vulnerabilities that the internetwork connections introduce. For a nominal data-rate below the fundamental limit, the effect of security breach can be diminished to an arbitrarily low level by channel coding. Notably, any nominal data-rate above the fundamental limit is not achievable; hence, a packet-loss distortion is introduced to keep the data-rate below the fundamental limit. Moreover, the fundamental limit is used to find the optimal number of internetwork connections between two networks under prescribed data-rate and packet-loss distortion constraints.

Natural Brain-Inspired Intelligence for Non-Gaussian and Nonlinear Environments with Finite Memory

The cyber processing layer of smart systems based on a cognitive dynamic system (CDS) can be a good solution for better decision making and situation understanding in non-Gaussian and nonlinear environments (NGNLE). The NGNLE situation understanding means deciding between certain known situations in NGNLE to understand the current state condition. Here, we report on a cognitive decision-making (CDM) system inspired by the human brain decision-making. The simple low-complexity algorithmic design of the proposed CDM system can make it suitable for real-time applications. A case study of the implementation of the CDS on a long-haul fiber-optic orthogonal frequency division multiplexing (OFDM) link was performed. An improvement in Q-factor of ~7 dB and an enhancement in data rate efficiency ~43% were achieved using the proposed algorithms. Furthermore, an extra 20% data rate enhancement was obtained by guaranteeing to keep the CDM error automatically under the system threshold. The proposed system can be extended as a general software-based platform for brain-inspired decision making in smart systems in the presence of nonlinearity and non-Gaussian characteristics. Therefore, it can easily upgrade the conventional systems to a smart one for autonomic CDM applications.

Data Rate Enhancement in Optical Camera Communications Using an Artificial Neural Network Equaliser

In optical camera communication (OCC) systems leverage on the use of commercial off-the-shelf image sensors to perceive the spatial and temporal variation of light intensity to enable data transmission. However, the transmission data rate is mainly limited by the exposure time and the frame rate of the camera. In addition, the camera's sampling will introduce intersymbol interference (ISI), which will degrade the system performance. In this paper, an artificial neural network (ANN)-based equaliser with the adaptive algorithm is employed for the first time in the field of OCC to mitigate ISI and therefore increase the data rate. Unlike other communication systems, training of the ANN network in OCC is done only once in a lifetime for a range of different exposure time and the network can be stored with a look-up table. The proposed system is theoretically investigated and experimentally evaluated. The results record the highest bit rate for OCC using a single LED source and the Manchester line code (MLC) non-return to zero (NRZ) encoded signal. It also demonstrates 2 to 9 times improved bandwidth depending on the exposure times where the system's bit error rate is below the forward error correction limit.

The Narrowband Internet of Things (NB-IoT) Resources Management Performance State of Art, Challenges, and Opportunities

The Narrowband Internet of Things (NB-IoT) has been introduced in the 3rd Generation Partnership Project (3GPP) Rel-13 with the aim to provide low-cost, low-power, wide-area cellular connectivity for the Internet of Things. With the exponentially increasing number of connected wireless devices in the order of 100 billion, it has become crucial that researchers develop efficient resource management techniques to meet the 5 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> Generation (5G) quality of service (QoS) requirements. Recently, several research challenges including the low modulation data rates, energy-expensive channel coding techniques, and the fast-growing number of connected devices have been identified as some of the main issues encountered in the design and deployment of NB-IoT systems. In addition, several techniques have emerged in the literature to resolve some of these challenges of NB-IoT systems. However, the research activities towards the enhancement of the NB-IoT resource management are yet to continue in the next half-decade before, high data rates, energy-efficient, and scalable NB-IoT specifications can be released for the standardisation and commercialisation. Considering the limited number of existing surveys of such technical enhancement approaches in a broader perspective (i.e. energy efficiency, data rate performance and scalability) and also the non-existence, to the best of our knowledge, of a comparative survey, this paper seeks to elaborate, describe and compare the performances of such resources management approaches. Of the multiple NB-IoT resources, the focus of this paper is on the data rate, energy efficiency, and scalability enhancement schemes that have been proposed for the last three years. The contribution of the paper lies in the analysis, synthesis, comparison and summarised alignments of some of the major existing schemes towards identifying challenges faced by the NB-IoT development. Finally, this work seeks to identify research challenges, open questions, and opportunities that could arise from the existing techniques analysed.

Waveform and Space Precoding for Next Generation Downlink Narrowband IoT

Narrowband Internet of Things (NB-IoT) was introduced by 3GPP in low power wide area network to support low power and wide coverage applications. Since it follows long term evolution standard, its signal quality is guaranteed and its deployment is straightforward via reusing existing infrastructures. Current NB-IoT supports low data rate services via using low order modulation formats for the purpose of power saving. However, with the increase of data rate driven applications, next generation NB-IoT would require data rate enhancement techniques without consuming extra battery power. In this paper, a downlink framework, using a nonorthogonal signal waveform for next generation enhanced NB-IoT (eNB-IoT), is proposed and experimentally tested in both single-antenna and multiantenna systems. In the single-antenna scenario, waveform precoding is used to pre-equalize the self-created inter carrier interference distorted signal waveform. For the multiantenna multiuser scenario, both waveform and antenna space precoding have to be used. Measured results show that in both single-antenna and multiantenna systems, the proposed signal waveform in eNB-IoT can increase data rate by ~11% compared with NB-IoT occupying the same spectral resource in similar receiver computational complexity.

Brain-Inspired Cognitive Decision Making for Nonlinear and Non-Gaussian Environments

The autonomic-computing layer of the smart systems based on a cognitive dynamic system (CDS) is proposed as a solution for better decision making and situation understanding in non-Gaussian and nonlinear environments (NGNLE). Here, we report on a cognitive decision-making (CDM) system inspired by the human brain decision-making process. Furthermore, it is designed based on CDS for CDM and internal commands. The simple low complexity algorithmic design of the proposed system can make it suitable for real-time applications. A case study of the implementation of the CDS was done on a long-haul fiber-optic orthogonal frequency division multiplexing (OFDM) link. An improvement in Q-factor of 3.5 dB as well as 23.3% data rate efficiency enhancement are achieved using the proposed algorithms with an extra 20% data rate enhancement by guaranteeing to keep CDM error automatically under the system threshold. The proposed system can be extended as a general software-based platform for brain-inspired decision making in smart systems in the presence of nonlinearity and non-Gaussian characteristics. Therefore, it can easily upgrade the conventional systems to a smart one for autonomic CDM applications.

A Survey on 5G Millimeter Wave Communications for UAV-Assisted Wireless Networks

In recent years, unmanned aerial vehicles (UAVs) have received considerable attention from regulators, industry and research community, due to rapid growth in a broad range of applications. Particularly, UAVs are being used to provide a promising solution to reliable and cost-effective wireless communications from the sky. The deployment of UAVs has been regarded as an alternative complement of existing cellular systems, to achieve higher transmission efficiency with enhanced coverage and capacity. However, heavily utilized microwave spectrum bands below 6 GHz utilized by legacy wireless systems are insufficient to attain remarkable data rate enhancement for numerous emerging applications. To resolve the spectrum crunch crisis and satisfy the requirements of 5G and beyond mobile communications, one potential solution is to use the abundance of unoccupied bandwidth available at millimeter wave (mmWave) frequencies. Inspired by the technique potentials, mmWave communications have also paved the way into the widespread use of UAVs to assist wireless networks for future 5G and beyond wireless applications. In this paper, we provide a comprehensive survey on current achievements in the integration of 5G mmWave communications into UAV-assisted wireless networks. More precisely, a taxonomy to classify the existing research issues is presented, by considering seven cutting-edge solutions. Subsequently, we provide a brief overview of 5G mmWave communications for UAV-assisted wireless networks from two aspects, i.e., key technical advantages and challenges as well as potential applications. Based on the proposed taxonomy, we further discuss in detail the state-of-the-art issues, solutions, and open challenges for this newly emerging area. Lastly, we complete this survey by pointing out open issues and shedding new light on future directions for further research on this area.

Dual-function radar-communications using QAM-based sidelobe modulation

Spectrum sharing using a joint platform for radar and communication systems has attracted significant attention in recent years. In this paper, we propose a novel dual-function radar-communications (DFRC) strategy to embed quadrature amplitude modulation (QAM) based communication information in the radar waveforms by exploiting sidelobe control and waveform diversity. The proposed information embedding technique can support multiple communication receivers located in the sidelobe region. In addition to the information broadcasting, the developed approach enables multi-user access by allowing simultaneous transmission of distinct information streams to the communication receivers located in different directions. We prove that the proposed technique ensures a significant data rate enhancement compared to the existing techniques. Moreover, the developed DFRC strategy generalizes the mathematical framework of the existing sidelobe control-based information embedding techniques.

Enhancement of Data Rate and Packet Size in Image Sensor Communications by Employing Constant Power 4-PAM

Image sensor communications (ISC) is a scheme to make the LED lamp replace access points or beacons in indoor environments. Its application has been limited, however, due to its low data rate and small packet size. To resolve these problems, we propose a new ISC scheme using 4-PAM modulation and a parallel packet structure. The constant power 4-PAM signal was designed to have constant optical power in each symbol to eliminate the flickering effect. The experiments show that a data rate more than 2.6 times higher than the existing on - off keying schemes was achieved. In addition, it is demonstrated that the packet length can reach more than several frames while it is limited to less than a frame using the existing schemes. The limiting factors of N-PAM levels and packet size are analyzed in this paper to further improvement. All these results are demonstrated through simulations and experiments.

Transmitter Design and Hardware Considerations for Different Space Modulation Techniques

Space modulation techniques (SMTs), in which some or all of the data bits modulate a block of spatial constellation symbol, are promising candidates for future 5G wireless systems. They promise data rate enhancements while maintaining low energy consumption, hardware cost, and computational complexity. As such, they attracted significant research interest in the past few years. One of the major assets of SMTs is the assumption that they can operate with a single RF chain at the transmitter even though multiple antennas might be activated at one time instant. Thus far, this claim is anticipated in several research articles but the transmitter designs of the different SMTs with a single RF chain are not addressed yet in the literature. SMTs include different system configurations, such as spatial modulation, space shift keying, quadrature spatial modulation, and quadrature space shift keying. The required hardware components to implement a transmitter for each of these systems with the minimum number of RF-chains are discussed in this paper. In addition, hardware limitations and the impact of different hardware blocks on the overall system performance are discussed. Besides, a comparison among different schemes along with conventional spatial multiplexing algorithm in terms of power consumption, hardware cost, probability of error, and receiver computational complexity is presented. It is shown that some of these techniques can operate without any RF-chain while a single-RF chain is sufficient for other systems. Moreover, these schemes can be traded off in terms of energy savings, complexity, performance, and cost.

A Novel and Efficient Vector Quantization Based CPRI Compression Algorithm

The future wireless network, such as the Centralized Radio Access Network (C-RAN), will need to deliver data rate about 100–1000 times the current fourth-generation (4G) technology. For the C-RAN-based network architecture, there is a pressing need for tremendous enhancement of the effective data rate of the common public radio interface (CPRI). Compression of CPRI data is one of the potential enhancements. In this paper, we introduce a vector quantization based compression algorithm for CPRI links, utilizing the Lloyd algorithm. Methods to vectorize the I/Q samples and enhanced initialization of the Lloyd algorithm for codebook training are investigated for improved performance. Multistage vector quantization and unequally protected multigroup quantization are considered to reduce codebook search complexity and codebook size. Simulation results show that our solution can achieve compression of four times for uplink and 4.5 times for downlink, within $2\%$ error vector magnitude (EVM) distortion. Remarkably, vector quantization codebook proves to be quite robust against data modulation mismatch, fading, signal-to-noise ratio (SNR), and Doppler spread.