Next-generation Wireless Communication Research Articles

Frequency-Selective Surface Based on Negative-Group-Delay Bismuth–Mica Medium

Negative group delay may be observed in dispersive media with anomalous dispersion in a certain frequency range. The fact that an outgoing wave packet precedes an incoming one does not violate the causality principle but is only a consequence of a waveform reshaping. This effect is observed in media such as photonic crystals, hyperbolic and epsilon-near-zero metamaterials, undersized waveguides, subwavelength apertures, side-by-side prisms, and resonant circuits at various frequencies. The current work is devoted to the design of a simple negative-group-delay medium with tunable properties in the THz frequency range. This medium consists of a bismuth-based frequency-selective surface on a dielectric substrate and may be tuned both statically and dynamically. While a geometry variation defines a main form of an effective permittivity dispersion and group delay/group velocity spectra, an external voltage allows one to adjust them with high precision. For the configuration proposed in this work, all frequency regions with noticeable change in group delay/group velocity lie within atmospheric transparency windows, which are to be used in 6G communications. This medium may be applied to THz photonics for a tunable phase-shift compensation, dispersion management in systems of THz signal modulation, and for encoding in next-generation wireless communication systems.

A Novel Collision Avoidance Strategy with D2D Communications for UAV Systems

In recent years, safety operation issues related to the autonomous flight of unmanned aerial vehicles (UAVs) have become popular research and development topics worldwide. Among all UAV applications, multiple UAV-related applications are emerging due to the integration of UAVs into 6G networks, which is an important topic for next-generation wireless communication systems. For multiple UAV applications, flight safety among UAVs is the most significant issue. Therefore, collision avoidance for UAVs has become an emerging topic in UAV-related research. In the past, although many UAV collision avoidance methods have been proposed, there is still a probability of other problems, such as no possible avoidance route and unmanaged UAVs that are without centralized control, which both result in an unpredictable risk of collisions. In this study, we investigate the current existing methods and propose novel collision avoidance methods based on the elastic collision principle. To verify the performance of the proposed methods, we also conduct simulations in this paper to demonstrate their effectiveness. From the simulation results, it can be seen that the proposed methods can effectively perform collision avoidance for multiple UAVs. Specifically, using the proposed methods, all UAVs can reach their destination points within reasonable time resources without any collision, validating the effectiveness of the proposed methods.

Multi Frequency Controllable In-Band Suppressions in a Broad Bandwidth Microstrip Filter Design for 5G Wi-Fi and Satellite Communication Systems Utilizing a Quad-Mode Stub-Loaded Resonator

The key elements used for receiving and processing signals in communication systems are the bandpass filters. Initially, a common operating mechanism was applied for the design of broadband filters, i.e., by cascading low-pass filters or high-pass filters using multiple line resonators with length quarter-half- or full-wavelength with central frequency, but using these approaches, the design topology becomes expensive and complex. The above mechanisms can be possibly overcome using a planar microstrip transmission line structure due to its simple design fabrication procedure and low cost. So, pointing out the above problems in bandpass filters such as low-cost, low insertion loss, and good out-of-band performance, this article presents a broadband filter with multifrequency suppression capability at 4.9 GHz, 8.3 GHz, and 11.5 GHz using a T-shaped shorted stub-loaded resonator with a central square ring coupled to the basic broadband filter. Initially, the C-shaped resonator is utilized for the formation of a stopband at 8.3 GHz for a satellite communication system, and then a shorted square ring resonator is added to the existing C-shaped structure for the realization of two more stopbands at 4.9 GHz and 11.5 GHz for 5G (WLAN 802.11j) communication, respectively. The overall circuit area covered with the proposed filter is 0.52 λg × 0.32 λg (λg is the wavelength of the feed lines at frequency 4.9 GHz). All the loaded stubs are folded in order to save the circuit area, which is an important requirement of next-generation wireless communication systems. The proposed filter has been analyzed using a well-known transmission line theory, even–odd-mode, and simulated with the 3D software HFSS. After the parametric analysis, some attractive features were obtained, i.e., compact structure, simple planar topology, low insertion losses of 0.4 dB over the entire band, good return loss greater than 10 dB, and independently controlled mutli stopbands, which make the proposed design unique and can be used in various wireless communication system applications. Finally, a Rogers RO-4350 substrate is selected for the fabrication of the prototype using an LPKF S63 ProtoLaser machine and then measured using a ZNB20 vector network analyzer for matching the simulated and measured results. After testing the prototype, a good agreement was found between the results.

Plasmonics for microwave photonics in the THz range

THz frequencies offer enormous amounts of bandwidth, which could solve the current speed bottleneck for next-generation wireless communications. Recent reports show sub-THz links offering capacities of hundreds of Gbit/s, finally approaching those of state-of-the-art optical transmission channels. Non-etheless, generation, transport, detection and processing of signals in the THz range is far from being a trivial task. Even though the recent evolution of integrated technology is starting to indicate that chip-scale THz technology could gradually close the so-called “THz gap,” much work still needs to be done to enable functional systems, in particular in terms of efficiency. Photonics can be of help, thanks to its extremely low loss and broad bandwidth. Yet, a particularly critical aspect hindering the deployment of THz technology is that state-of-the-art photonics devices generally do not offer sufficient electro-optical bandwidth to process THz signals. Plasmonics, by focusing electromagnetic surface waves at sub-wavelength scales, can play a key role in this quest, as it finally enables the realization of electro-optical devices such as modulators and detectors displaying sufficient compactness and speeds to reach the THz range. This paper overviews recent achievements on plasmonic-based modulators displaying characteristics of speed, efficiency and linearity that enable high-performance access to this much desired frequency range.

Highly reconfigurable silicon integrated microwave photonic filter towards next-generation wireless communication

Integrated microwave photonic filters (IMPFs) are capable of offering unparalleled performances in terms of superb spectral fineness, broadband, and more importantly, the reconfigurability, which encounter the trend of the next-generation wireless communication. However, to achieve high reconfigurability, previous works should adopt complicated system structures and modulation formats, which put great pressure on power consumption and controlment, and, therefore, impede the massive deployment of IMPF. Here, we propose a streamlined architecture for a wideband and highly reconfigurable IMPF on the silicon photonics platform. For various practical filter responses, to avoid complex auxiliary devices and bias drift problems, a phase-modulated flexible sideband cancellation method is employed based on the intensity-consistent single-stage-adjustable cascaded-microring (ICSSA-CM). The IMPF exhibits an operation band extending to millimeter-wave (≥30 GHz), and other extraordinary performances including high spectral resolution of 220 MHz and large rejection ratio of 60 dB are obtained. Moreover, Gb/s-level RF wireless communications are demonstrated for the first time towards real-world scenarios. The proposed IMPF provides broadband flexible spectrum control capabilities, showing great potential in the next-generation wireless communication.

Spectrum sensing-focused cognitive radio network for 5G revolution

The cognitive radio network (CRN), an instrumental part of the next-generation wireless communication systems, is mainly dependent on spectrum sensing to function properly. The radio spectrum can help in clean energy transition and load capacity factors by providing a more efficient and accurate spectrum utilization. By using it, the number of spectrums that is used for communication can be optimized, which can reduce the amount of energy consumed by the network. Additionally, 5G radio spectrum sensing can be used to identify and classify different types of signals, which can help reduce the amount of interference in the network and improve the efficiency of energy utilization. It can also allow for the digitization of clean energy infrastructure and facilitate better decision-making processes that take into account environmental impacts while optimizing energy use because of its efficient characteristics like non-linearity, detection, scalability, robustness, generalization, non-stationarity in wireless environments, dynamic entity, weighted sum of Gaussian functions centered at specific frequencies, and robustness against noise and interference. It can adapt to noise and interference by adjusting its parameters, and this allows accurate distinguishing between primary and secondary users in the wireless spectrum, which is why a radial basis function is a popular choice for spectrum sensing in 5G networks. Radial basis function networks (RBFNs) can work better in 5G spectrum sensing for better signal classification, dynamic adaptation, fast detection, faster decision-making, and improved noise and interference reduction. One of the most sought-after goals in the field of wireless research is the creation of spectrum-sensing technology that is dependable and intelligent because multilayer learning approaches are inappropriate for dealing with time-series data due to the higher misclassification rate and inherent computational complexity. To address this, the study proposed the radial basis function network that learns the temporal aspects from spectral data and makes use of additional environmental statistics such as frequency, efficiency, energy, spectrum allocation, distance, and duty-cycle time, which are considered environmental data that may be used to fine-tune sensor performance. The scheme is simulated with real-time parameters, and the results are quite promising in terms of evaluation parameters.

Performance of IRS-Aided FD Two-Way Communication Network With Imperfect SIC

Intelligent reflecting surface (IRS) is a promising technology to deploy reconfigurable and cost-effective next-generation wireless communication systems. In this work, we investigate the performance of an IRS-aided two-way communication network over Rayleigh fading channels, where downlink and uplink transmission between the base station and the user equipment is established in full-duplex mode. We take into account the impact of residual self-interference (RSI), which results from imperfect self-interference cancellation. We derive the analytical expressions of outage probability (OP), asymptotic OP, and obtain diversity order of the system. We also derive ergodic capacity in terms of the Meijer-G function. Further, we derive the analytical expressions of average symbol error rate (ASER) for general order rectangular quadrature amplitude modulation (QAM), cross QAM, and hexagonal QAM. We highlight the impact of reflecting elements, RSI, and other system parameters on the performance of the considered network and also compare the ASER of various QAM constellations. Finally, Monte-Carlo simulations validate the derived analytical expressions.

Energy-efficient non-orthogonal multiple access for wireless communication system

<p>Non-orthogonal multiple access (NOMA) has been recognized as a potential solution for enhancing the throughput of next-generation wireless communications. NOMA is a potential option for 5G networks due to its superiority in providing better spectrum efficiency (SE) compared to orthogonal multiple access (OMA). From the perspective of green communication, energy efficiency (EE) has become a new performance indicator. A systematic literature review is conducted to investigate the available energy efficient approach researchers have employed in NOMA. We identified 19 subcategories related to EE in NOMA out of 108 publications where 92 publications are from the IEEE website. To help the reader comprehend, a summary for each category is explained and elaborated in detail. From the literature review, it had been observed that NOMA can enhance the EE of wireless communication systems. At the end of this survey, future research particularly in machine learning algorithms such as reinforcement learning (RL) and deep reinforcement learning (DRL) for NOMA are also discussed.</p>

Lossy State Communication over Fading Multiple Access Channels.

Joint communications and sensing functionalities integrated into the same communication network have become increasingly relevant due to the large bandwidth requirements of next-generation wireless communication systems and the impending spectral shortage. While there exist system-level guidelines and waveform design specifications for such systems, an information-theoretic analysis of the absolute performance capabilities of joint sensing and communication systems that take into account practical limitations such as fading has not been addressed in the literature. Motivated by this, we undertake a network information-theoretic analysis of a typical joint communications and sensing system in this paper. Towards this end, we consider a state-dependent fading Gaussian multiple access channel (GMAC) setup with an additive state. The state process is assumed to be independent and identically distributed (i.i.d.) Gaussian, and non-causally available to all the transmitting nodes. The fading gains on the respective links are assumed to be stationary and ergodic and available only at the receiver. In this setting, with no knowledge of fading gains at the transmitters, we are interested in joint message communication and estimation of the state at the receiver to meet a target distortion in the mean-squared error sense. Our main contribution here is a complete characterization of the distortion-rate trade-off region between the communication rates and the state estimation distortion for a two-sender GMAC. Our results show that the optimal strategy is based on static power allocation and involves uncoded transmissions to amplify the state, along with the superposition of the digital message streams using appropriate Gaussian codebooks and dirty paper coding (DPC). This acts as a design directive for realistic systems using joint sensing and transmission in next-generation wireless standards and points to the relative benefits of uncoded communications and joint source-channel coding in such systems.

Polymer valley photonic crystals with honeycomb structures for terahertz waveguides

Terahertz (THz) band has promising applications in next-generation wireless communications and new sensing technologies. However, the on-chip transmission of THz waves will encounter strong scattering at sharp corner structures of waveguides. Recently, valley photonic crystals (VPC) offer new possibilities for high-fidelity transmission of THz wave along complex shape waveguides. The VPC-based waveguide overcomes defects and sharp corners, probably resulting in high-performance on-a-chip THz devices. The THz VPC with polymer materials can be easy and low-cost building with 3D printing technology. In this paper, the VPC waveguides operating around 300 GHz are constructed using honeycomb lattices on a thin polymer plate. The mirror symmetry is broken by proper air-circular apertures located in the honeycomb lattice with a nontrivial band structure. Then the influences on the band structure by the polymer refractive index ranging from 1.5∼2.0, the thickness of the sheet, and the asymmetry of aperture diameters in the lattice are discussed. The transmission of straight, zigzag, and “omega” waveguides made of the polymer VPCs is simulated. The results demonstrate their high transmission efficiency and robustness to scattering from sharp bending above −10 dB with an 8-GHz bandgap. The proposed polymer VPC structure paves way for THz applications such as efficient beam splitters, low-loss complex-shaped waveguides, and robust delay lines.

A Survey on Optimal Channel Estimation Methods for RIS-Aided Communication Systems

Next-generation wireless communications aim to utilize mmWave/subTHz bands. In this regime, signal propagation is vulnerable to interferences and path losses. To overcome this issue, a novel technology has been introduced, which is called reconfigurable intelligent surface (RIS). RISs control digitally the reflecting signals using many passive reflector arrays and implement a smart and modifiable radio environment for wireless communications. Nonetheless, channel estimation is the main problem of RIS-assisted systems because of their direct dependence on the system architecture design, the transmission channel configuration and methods used to compute channel state information (CSI) on a base station (BS) and RIS. In this paper, a concise survey on the up-to-date RIS-assisted wireless communications is provided and includes the massive multiple input-multiple output (mMIMO), multiple input-single output (MISO) and cell-free systems with an emphasis on effective algorithms computing CSI. In addition, we will present the effectiveness of the algorithms computing CSI for different communication systems and their techniques, and we will represent the most important ones.

Ergodic Achievable Rate Maximization of RIS-Assisted Millimeter-Wave MIMO-OFDM Communication Systems

Reconfigurable intelligent surface (RIS) has attracted extensive attention in recent years. However, most research focuses on the scenario of the narrowband and/or instantaneous channel state information (CSI), while wide bandwidth with the use of millimeter-wave (mmWave) (including sub-Terahertz) spectrum is a major trend in next-generation wireless communications, and statistical CSI is more practical to obtain in realistic systems. Thus, we {consider} the ergodic achievable rate of RIS-assisted mmWave multiple-input multiple-output orthogonal frequency division multiplexing communication systems. The widely used Saleh-Valenzuela channel model is adopted to characterize the mmWave channels and only the statistical CSI is available. We first derive the approximations of the ergodic achievable rate by means of the majorization theory and Jensen's inequality. Then, an alternating optimization based algorithm is proposed to maximize the ergodic achievable rate by jointly designing the transmit covariance matrix at the base station and the reflection coefficients at the RIS. Specifically, the design of the transmit covariance matrix is transformed into a power allocation problem and solved by spatial-frequency water-filling. The reflection coefficients are optimized by the Riemannian conjugate gradient algorithm. Simulation results corroborate the effectiveness of the proposed algorithms.

A Compact High-Isolation Four-Element MIMO Antenna with Asymptote-Shaped Structure

The demand for high-speed wireless communication systems has led to the development of ultrawide-band (UWB) antennas with a compact size and high performance. In this paper, we propose a novel four-port multiple-input multiple-output (MIMO) antenna with an asymptote-shaped structure that overcomes the limitations of existing designs for UWB applications. The antenna elements are placed orthogonally to each other for polarization diversity, and each element features a stepped rectangular patch with a tapered microstrip feedline. The unique structure of the antenna significantly reduces its dimensions to 42 × 42 mm2 (0.43λ×0.43λ@ 3.09GHz), making it highly desirable for use in small wireless devices. To further enhance the antenna's performance, we use two parasitic tapes on the ground plane at the back as decoupling structures between adjacent elements. The tapes are designed in a windmill shape and a rotating extended cross shape, respectively, to further improve the isolation. We fabricated and measured the proposed antenna design on a single-layer substrate (FR4) with a dielectric constant of 4.4 and a thickness of 1 mm. The measured results show that the impedance bandwidth of the antenna is 3.09-12 GHz, with an isolation of -16.4 dB, an envelope correlation coefficient (ECC) of 0.02, a diversity gain (DG) of 9.991 dB, an average total effective reflection coefficient (TARC) of -20 dB, an overall group delay value less than 1.4 ns, and a peak gain of 5.1 dBi. Although there may be some antennas that have better performance in one or two specific aspects, our proposed antenna has an excellent trade-off among all the antenna characteristics including bandwidth, size, and isolation. The proposed antenna also exhibits good quasi-omnidirectional radiation properties, making it well-suited for a range of emerging UWB-MIMO communication systems, particularly in small wireless devices. In summary, the compact size and ultrawide-band capabilities of the proposed MIMO antenna design, coupled with its improved performance compared to other recent UWB-MIMO designs, make it a promising candidate for 5G and next-generation wireless communication systems.

Multifunctional carbon nanotubes-based hybrid aerogels with high-efficiency electromagnetic wave absorption at elevated temperature

In the complex engineering applications of electromagnetic (EM) wave-absorbing materials, it is insufficient for these materials to exhibit only efficient EM wave attenuation ability. EM wave-absorbing materials featuring numerous multifunctional properties are increasingly attractive for next-generation wireless communication and smart devices. Herein, we constructed a lightweight and robust multifunctional hybrid aerogel consisting of carbon nanotubes/aramid nanofibers/polyimide with low shrinkage and high porosity. The hybrid aerogels exhibit excellent EM wave attenuation, with an effective absorption bandwidth covering the entire X-band from 25 °C to 400 °C. The conductive loss capacity of the hybrid aerogel is enhanced under thermal drive, which results in an enhanced ability to attenuate EM waves, as evidenced by the fact that the best-fit thickness drops from 5.3 to 3.6 mm with increasing temperature. In addition, the hybrid aerogels are capable to efficiently absorb sound waves, with an average absorption coefficient as high as 0.86 at 1–6.3 kHz, and they exhibit superior thermal insulation properties, with a thermal conductivity as low as 41 ± 2 mW/mK. They are thus suitable for applications in the anti-icing and infrared stealth fields. The prepared multifunctional aerogels have considerable potential for EM protection, noise reduction, and thermal insulation in harsh thermal environments.

Reconfigurable terahertz light harvesting with MoTe2 hybrid metasurface.

Near-perfect light harvesting of a metasurface-based absorber paves the way for achieving numerous potential applications in sensing, cloaking, and photovoltaics. Here, we present a reconfigurable perfect absorber based on a molybdenum ditelluride (MoTe2) hybrid metasurface at terahertz (THz) frequency. By investigating the optical response of metasurface-based absorbers, a reconfigurable switching of dual-frequency perfect absorption to a new single-frequency absorption takes place when light illuminates MoTe2. Moreover, the absorption mechanism of the hybrid metasurface is well demonstrated with the analytical coupled-dipole model and impedance analysis. The proposed reconfigurable THz meta-absorber provides a new, to the best of our knowledge, route for active radar stealth, frequency-selective detection, and next-generation wireless communication.

On Performance of Intelligent Reflecting Surface Aided Wireless Powered IoT Network With HIs

Intelligent reflecting surface (IRS) is envisioned as a key technology for the next-generation wireless communication systems that enhances coverage and performance by reconfiguring the wireless propagation environment. In this letter, the performance of an IRS-aided wireless-powered internet-of-things (IoT) network over Rayleigh fading channels is investigated that consists a power station, an IRS, an access point, and IoT devices. In particular, the impact of transceiver hardware impairments (HIs) is considered. An IoT node selection strategy is adopted that maximizes the harvested energy and improves the system performance. The closed-form expressions of outage probability (OP), ergodic capacity, and symbol error rate are derived by using the Gaussian Chebyshev Quadrature method. Further, the closed-form expressions of the asymptotic OP and asymptotic ergodic capacity are derived and the diversity order of the considered network is obtained. The impact of HIs, overall system ceiling effect, IoT devices, reflecting elements, and various system parameters on the considered network are highlighted. Finally, the Monte-Carlo simulations are performed to verify the derived closed-form expressions.

NOMA-enabled Cooperative V2V Communications with Fixed-Gain AF Relaying

By virtue of its improving bandwidth efficiency along with user fairness, non-orthogonal multiple access (NOMA) technique is considered a promising method for next-generation wireless communication systems. Since fading effect of wireless channels in vehicle-to-vehicle (V2V) communication systems are more severe than those in traditional systems, in this study, we employ the power-domain downlink NOMA technique in cooperative V2V communication systems to enhance data transmission capacity and network efficiency. In the proposed system, the base station communicates with two vehicular nodes, namely near and far users, through a relay vehicle employing the fixed-gain amplify-and-forward scheme. In real-life scenarios, the relay and the users move in high velocities; hence, the corresponding fading channels between these nodes are exposed as having double-Rayleigh fading characteristic in which the fading coefficient of a wireless channel is modeled as the product of two Rayleigh distributed random variables. To analyze the system performance, we first investigate the outage probability and derive its exact closed-form expressions for the near and far users. Then, we make the exact ergodic capacity analysis and obtain the closed-form solution for the near user. Furthermore, outage and ergodic performances of the NOMA-enabled system are compared to the simulation results of the traditional orthogonal multiple access approach. We also give analytic and numerical results to evaluate the performance of the proposed system and show the consistency of Monte-Carlo simulations with analytical derivations. It is observed that even with the small power allocation, both performances of the near user mostly outperform the far user.

Rational design of heterointerface between MoO2 and N-doped carbon with tunable electromagnetic interference shielding capacity

Exploring highly efficient electromagnetic interference (EMI) shielding filler is urgently desired for next-generation wireless communication and integrated electronics. In this regard, a series of heterogeneous MoO2/N-doped carbon (MoO2/NC) nanorods with tunable conductivity have been successfully synthesized by regulating the pyrolysis temperature within 600, 700 and 800 °C. Profiting from the rational design of heterointerface and low-dimensional structure, the MoO2/NC powder achieves stronger EMI shielding capacity with the incremental temperature. It is found that the MoO2/NC-800 nanorods exhibit the optimal average EMI shielding effectiveness (SE) of 57.2 dB at a thickness of ∼0.3 mm in the X band. Meanwhile, the corresponding shielding mechanisms of MoO2/NC nanorods are also elaborately explained. More interestingly, the increase of sintering temperature makes an obvious effect on absorption loss but has little influence on reflection loss, demonstrating that adjusting the pyrolysis temperature is an effective strategy to strengthen the electromagnetic energy dissipation.

Enhanced Performance of a Cascaded Receiver Consisting of a DNN-Based Waveform-to-Symbol Converter and Modified NN-Based DD-LMS in CAP Underwater VLC System

Underwater visible light communication (UVLC) based on LEDs has become a competitive candidate, which is able to provide high data rates, low latency and low cost for next-generation wireless communication technologies. However, it is still challenging to achieve high-speed communication because of bottleneck problems such as bandwidth limitation and linear and nonlinear distortions. Traditional Deep-learning Neural Network (DNN)-based waveform-to-symbol converter is verified to be an effective method to alleviate them, but impractical due to high complexity. To achieve a better tradeoff between communication performance and computation complexity, a cascaded receiver consisting of a DNN-based waveform-to-symbol converter and modified Neural Network (NN)-based decision-directed least mean square (DD-LMS) is then innovatively proposed. With fewer taps and nodes than the traditional converter, the front-stage converter could mitigate the majority of Inter-Symbol Interference (ISI) and signal nonlinear distortions. Then modified NN-based DD-LMS is cascaded to improve communication performance by reducing phase offset, making received constellation points more concentrated and closer to standard constellation points. Compared with the traditional converter, the cascaded receiver could achieve 89.6% of signal Vpp dynamic range with 12.4% of complexity in the 64APSK UVLC system. Moreover, the ratio of signal Vpp dynamic range and total trainable parameters is 1.24 × 10−1 mV, while that of the traditional converter is 1.95 × 10−2 mV. The cascaded receiver used in 64APSK UVLC systems is experimentally verified to achieve enhanced performance, thus as a promising scheme for future high-speed underwater VLC.

Multiport Single Element Mimo Antenna Systems: A Review

In response to the increasing demand for voice, data, and multimedia applications, the next generation of wireless communication systems is projected to provide faster data rates and better service quality to customers. Techniques such as Multiple-Input-Multiple-Output (MIMO) and diversity are being studied and implemented to meet the needs of next-generation wireless communication systems. Embedding multiple antennas into the same antenna system is seen as a promising solution, which can improve both the system's channel capacity and the communication link's quality. However, for small handheld and portable devices, embedding many antennas into a single device in a small area and at the same time providing good isolation becomes a challenge. Hence, designing a shared antenna system with multiple feed ports with equivalent or better performance characteristics as compared to the approach of multiple antennas with multiple feed ports is a promising advantage which can reduce the size and cost of manufacturing. This paper intends to provide an in-depth review of different MIMO antenna designs with common radiators covering various antenna design aspects such as isolation techniques, gain, efficiency, envelope correlation coefficient, and size, etc. There is also a discussion of the mathematical concepts of MIMO and different isolation techniques, as well as a comparative analysis of different shared radiator antenna designs. The literature review shows that only very few antennas' design with common radiator have been suggested in the available literature at present. Therefore, in this review paper, we have endeavored to study different antennas' designs with common radiator. A comparison is provided of their performance improvement techniques in a holistic way so that it can lead to further develop the common radiator multiport antenna systems and realize the promising advantages they offer.