MIMO Beamforming

2009 ◽  
pp. 240-263
Author(s):  
Qinghua Li ◽  
Xintian Eddie Lin ◽  
Jianzhong ("Charlie") Zhang
Keyword(s):  
Multiple Input Multiple Output ◽  
Industrial Applications ◽  
Antenna System ◽  
Limiting Factor ◽  
Transmit Beamforming ◽  
Underlying Principle ◽  
Input Multiple Output ◽  
Time Division ◽  
Channel Reciprocity ◽  
Mimo Beamforming

Transmit beamforming improves the performance of multiple-input multiple-output antenna system (MIMO) by exploiting channel state information (CSI) at the transmitter. Numerous MIMO beamforming schemes are proposed in open literature and standard bodies such as 3GPP, IEEE 802.11n and 802.16d/e. This chapter describes the underlying principle, evolving techniques, and corresponding industrial applications of MIMO beamforming. The main limiting factor is the cumbersome overhead to acquire CSI at the transmitter. The solutions are categorized into FDD (Frequency Division Duplex) and TDD (Time Division Duplex) approaches. For all FDD channels and radio calibration absent TDD channels, channel reciprocity is not available and explicit feedback is required. Codebook-based feedback techniques with various quantization complexities and feedback overheads are depicted in this chapter. Furthermore, we discuss transmit/receive (Tx/Rx) radio chain calibration and channel sounding techniques for TDD channels, and show how to achieve channel reciprocity by overcoming the Tx/Rx asymmetry of the RF components

scholarly journals A Graphene-Assembled Film Based MIMO Antenna Array with High Isolation for 5G Wireless Communication

2021 ◽  
Vol 11 (5) ◽  
pp. 2382
Author(s):  
Rongguo Song ◽  
Xiaoxiao Chen ◽  
Shaoqiu Jiang ◽  
Zelong Hu ◽  
Tianye Liu ◽  
...  
Keyword(s):  
Antenna Array ◽  
Antenna Arrays ◽  
Multiple Input Multiple Output ◽  
Frequency Selective Surface ◽  
Antenna System ◽  
Antenna Element ◽  
Mimo Antenna ◽  
High Isolation ◽  
Input Multiple Output ◽  
Alternative Material

With the development of 5G, Internet of Things, and smart home technologies, miniaturized and compact multi-antenna systems and multiple-input multiple-output (MIMO) antenna arrays have attracted increasing attention. Reducing the coupling between antenna elements is essential to improving the performance of such MIMO antenna system. In this work, we proposed a graphene-assembled, as an alternative material rather than metal, film-based MIMO antenna array with high isolation for 5G application. The isolation of the antenna element is improved by a graphene assembly film (GAF) frequency selective surface and isolation strip. It is shown that the GAF antenna element operated at 3.5 GHz has the realized gain of 2.87 dBi. The addition of the decoupling structure improves the isolation of the MIMO antenna array to more than 10 dB and corrects the antenna radiation pattern and operating frequency. The isolation between antenna elements with an interval of 0.4λ is above 25 dB. All experimental results show that the GAF antenna and decoupling structure are efficient devices for 5G mobile communication.

scholarly journals Mutual Coupling Reduction of DRA for MIMO Applications

2019 ◽  
Vol 8 (1) ◽  
pp. 75-81
Author(s):  
N. Al Shalaby ◽  
S. G. El-Sherbiny
Keyword(s):  
Mutual Coupling ◽  
Dielectric Material ◽  
Ground Plane ◽  
Multiple Input Multiple Output ◽  
Antenna System ◽  
Parasitic Element ◽  
Mimo Antenna ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Element Method

In this paper, A multiple input Multiple Output (MIMO) antenna using two Square Dielectric Resonators (SDRs) is introduced. The mutual coupling between the two SDRAs is reduced using two different methods; the first method is based on splitting a spiral slot in the ground plane, then filling the slot with dielectric material, "E.=2.2". The second method is based on inserting a copper parasitic element, having the same shape of the splitted Spiral, between the two SDRAs.  The effect of replacing the copper parasitic element with Carbon nanotubes (CNTs) parasitic element "SOC12 doped long-MWCNT BP" is also studied. The antenna system is designed to operate at 6 GHz. The analysis and simulations are carried out using finite element method (FEM). The defected ground plane method gives a maximum isolation of l8dB at element spacing of 30mm (0.6λo), whereas the parasitic element method gives a maximum isolation of 42.5dB at the same element spacing.

scholarly journals Nature Inspired MIMO Antenna System for Future mmWave Technologies

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1083
Author(s):  
Saifur Rahman ◽  
Xin-cheng Ren ◽  
Ahsan Altaf ◽  
Muhammad Irfan ◽  
Mujeeb Abdullah ◽  
...  
Keyword(s):  
Communication Systems ◽  
High Efficiency ◽  
Multiple Input Multiple Output ◽  
Antenna System ◽  
Potential Candidate ◽  
Mimo Antenna ◽  
Communication Devices ◽  
Input Multiple Output ◽  
Measured Efficiency ◽  
5G Communication

In this work, a new Multiple Input Multiple Output (MIMO) antenna system with a novel shape inspired by nature is proposed for Fifth-Generation (5G) communication systems. The antenna is designed on a Rogers 5880. The dielectric constant of the substrate is 2.2, and the loss tangent is assumed to be 0.0009. The gain of the system for the desired bandwidth is nearly 8 dB. The simulated and the measured efficiency of the proposed system is 95% and 80%, respectively. To demonstrate the capability of the system as a potential candidate for future 5G communication devices, MIMO key performance parameters such as the Envelope Correlation Coefficient (ECC) and Diversity Gain (DG) are computed. It is found that the proposed system has low ECC, constant DG, and high efficiency for the desired bandwidth.

scholarly journals Modified U-Shaped Resonator as Decoupling Structure in MIMO Antenna

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1321
Author(s):  
Amjad Iqbal ◽  
Ahsan Altaf ◽  
Mujeeb Abdullah ◽  
Mohammad Alibakhshikenari ◽  
Ernesto Limiti ◽  
...  
Keyword(s):  
Multiple Input Multiple Output ◽  
Equivalent Circuit Model ◽  
Separation Distance ◽  
Antenna System ◽  
Parametric Modelling ◽  
Mimo Antenna ◽  
Antenna Performance ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Simple Assembly

This paper presents an isolation enhancement of two closely packed multiple-input multiple-output (MIMO) antenna system using a modified U-shaped resonator. The modified U-shaped resonator is placed between two closely packed radiating elements resonating at 5.4 GHz with an edge to edge separation distance of 5.82 mm (λ∘/10). Through careful adjustment of parametric modelling, the isolation level of −23 dB among the densely packed elements is achieved. The coupling behaviour of the MIMO elements is analysed by accurately designing the equivalent circuit model in each step. The antenna performance is realized in the presence and absence of decoupling structure, and the results shows negligible effects on the antenna performance apart from mutual coupling. The simple assembly of the proposed modified U-shaped isolating structure makes it useful for several linked applications. The proposed decoupling structure is compact in nature, suppress the undesirable coupling generated by surface wave and nearby fields, and is easy to fabricate.

scholarly journals Emulating Realistic Bidirectional Spatial Channels for MIMO OTA Testing

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Wei Fan ◽  
Pekka Kyösti ◽  
Jesper Ø. Nielsen ◽  
Lassi Hentilä ◽  
Gert F. Pedersen
Keyword(s):  
Communication Systems ◽  
Experimental Validation ◽  
Multiple Input Multiple Output ◽  
Line Of Sight ◽  
Channel Models ◽  
Bidirectional Communication ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Time Division ◽  
Space Line

This paper discusses over the air (OTA) testing for multiple input multiple output (MIMO) capable terminals with emphasis on modeling bidirectional spatial channel models in multiprobe anechoic chamber (MPAC) setups. In the literature, work on this topic has been mainly focused on how to emulate downlink channel models, whereas uplink channel is often modeled as free space line-of-sight channel without fading. Modeling realistic bidirectional (i.e., both uplink and downlink) propagation environments is essential to evaluate any bidirectional communication systems. There have been works stressing the importance of emulating full bidirectional channel and proposing possible directions to implement uplink channels in the literature. Nevertheless, there is no currently published work reporting an experimental validation of such concepts. In this paper, a general framework to emulate bidirectional channels for time division duplexing (TDD) and frequency division duplexing (FDD) communication systems is proposed. The proposed technique works for MPAC setups with arbitrary uplink and downlink probe configurations, that is, possibly different probe configurations (e.g., number of probes or their configurations) in the uplink and downlink. The simulation results are further supported by measurements in a practical MPAC setup. The proposed algorithm is shown to be a valid method to emulate bidirectional spatial channel models.

scholarly journals A Novel 2.4-GHz Low-Profile Smart MIMO Antenna with Reconfigurable Frequency-Selective Reflectors

2020 ◽  
Vol 9 (2) ◽  
pp. 42-51
Author(s):  
C.-H. Tsai ◽  
J.-S. Sun ◽  
S.-J. Chung ◽  
J.-H. Tarng
Keyword(s):  
Multiple Input Multiple Output ◽  
Antenna System ◽  
Switching Network ◽  
Ieee 802.11A ◽  
Mimo Antenna ◽  
Low Profile ◽  
Specific Direction ◽  
Input Multiple Output ◽  
Frequency Selective ◽  
Beam Switching

In this paper, a new low-profile smart multiple-input multiple-output (MIMO) antenna system is presented for WiFi IEEE 802.11a/b/g/n/ac/ax applications. The proposed compact 2.4-GHz antenna system employs two beam-switching antenna cells for MIMO operation. Each antenna cell is composed of four reconfigurable frequency-selective reflectors (RFSRs) and a one-to-four switching feeding network. The RFSRs are constructed using a one-wavelength metal loop resonator, which functions as a radiating antenna or a wave reflector to reflect beams along a specific direction, as controlled by the switching network. The feeding switching network utilizes PIN diodes to adjust the phase and impedance required for changing the operational status of each RFSR. The overall dimensions of the antenna system, including the metallic ground, are 120 mm ´ 120 mm ´ 9.5 mm. Moreover, the measured operational bandwidth of the 2.4-GHz antenna is approximately 100 MHz, and the radiation efficiency of each directed beam is 40%–70%.

scholarly journals Wideband MIMO antenna for SCADA Wireless Communication Backhaul Application

2021 ◽  
Vol 12 (3) ◽  
pp. 4538-4547
Author(s):  
Nur Zafirah Bt Muhammad Zubir Et.al
Keyword(s):  
Wireless Communication ◽  
Ground Plane ◽  
Multiple Input Multiple Output ◽  
Radiation Characteristic ◽  
Antenna System ◽  
Mobile Telecommunication ◽  
Telecommunication System ◽  
Antenna Structure ◽  
Mimo Antenna ◽  
Input Multiple Output

A wideband multiple-input-multiple-output (MIMO) antenna system with common elements suitable for SCADA wireless communication backhaul application which is operating frequency of 0.85-2.6GHz that can cover global system for mobile communication (GSM) 900MHz and 1.8GHz, The Universal Mobile Telecommunication System (UMTS) 2GHz, Wi-Fi (2.4GHz) and Long Term Evolution (LTE) 2.6GHz is proposed. The proposed MIMO antenna system consists of four microstrip feedline with common radiating element and a frame shaped ground plane. A single port antenna also was designed and presented in this paper to show the process to design wideband MIMO antenna structure. The radiator of the MIMO antenna system is designed as the shape of modified rectangle with straight line at each corner to enhance the bandwidth frequency. To improve the isolation between ports, the ground plane is modified by inserting four L-slots in each corner to reduce mutual coupling. For an antenna efficiency of more than 60%, the simulated reflection coefficients are below -10dB for all ports at expected frequency. Simulated isolation is achieved greater than -10dB by using a modified ground plane. Also, a low envelope correlation coefficient (ECC) less than 0.1 and polarization diversity gain of about 10dB with the orthogonal mode of linear polarization and omnidirectional pattern during the analysis of the radiation characteristic are achieved. Therefore, the proposed design can be used for SCADA wireless communication backhaul application.

scholarly journals Design of a compact hexagonal structured dual band MIMO antenna using orthogonal polarization for WLAN and satellite applications

2019 ◽  
Vol 9 (5) ◽  
pp. 4217
Author(s):  
Aziz Dkiouak ◽  
Mohssine El Ouahabi ◽  
Alia Zakriti ◽  
Mohsine Khalladi ◽  
Aicha Mchbal
Keyword(s):  
Multiple Input Multiple Output ◽  
Antenna System ◽  
Dual Band ◽  
Orthogonal Polarization ◽  
Mimo Antenna ◽  
X Band ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Satellite Applications ◽  
Strip Lines

In this paper, a compact dual band multiple-input multiple-output (MIMO) antenna system for WLAN and X-band satellite applications (2.4/9.8 GHz respectively) is proposed. On the top face of the substrate, two antenna elements with a size of 20 × 24 mm2 are placed side by side and fed with matched orthogonal micro-strip lines. The two antenna elements have orthogonal polarization which can reduce the mutual coupling between its ports. The designed antenna system is fabricated and measured to validate the simulation results. The impedance bandwidths are about 370 MHz (2.19 to 2.56 GHz) and 630 MHz (9.44 to 10.07 GHz), while the obtained isolation is greater than 14 dB at the operating bands. Furthermore, the envelope correlation is less than 0.052 and 0.008 at 2.4 and 9.8 GHz, respectively. Hence the diversity gain is higher than 9.98 in the frequency bands of interest.

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