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Over-the-air Testing of a 32 x 32 Daisy Chain MIMO Antenna
... (A) Development of higher order MIMO arrays, such as 8 × 8 [12], 16 × 16 [13], and 32 × 32 [14,15] MIMO antenna systems, suitable for implementation in an automobile. One of the possible solutions to fulfilling this requirement is the use of a circular array in which a number of patch antennas are arranged in a cylindrical manner [7,8]. ...
... Micromachines 2020, 11, 871 3 of 25 (A) Development of higher order MIMO arrays, such as 8 × 8 [12], 16 × 16 [13], and 32 × 32 [14,15] MIMO antenna systems, suitable for implementation in an automobile. (B) Development of radiation pattern steering capability to achieve a large signal-to-noise power ratio (SNR) that can direct the peak radiation toward the communication target. ...
... This unique feature allows the SNR of the 32 subarray beams to be large, and simultaneously, the correlation to be small, which keeps the channel capacity in a high-bit rate condition, even with considerable dynamic motion of the car. Figure 5 shows a schematic diagram of a beam forming network for full-azimuth steering, which comprises switches, phase shifters, and power dividers [15]. Using this network, the four combinations of subarrays, as shown in Figure 4, can be chosen according to the angle of the incident wave to deliver signals to Elements #1-8 for achieving an in-phase state between a pair of elements. ...
This paper presents a multiple-input, multiple-output (MIMO) antenna system with the ability to perform full-azimuth beam steering, and with the aim of realizing greater than 20 Gbps vehicular communications. The MIMO antenna described in this paper comprises 64 elements arranged in a daisy chain array structure, where 32 subarrays are formed by pairing elements in each subarray; the antenna yields 32 independent subchannels for MIMO transmission, and covers all communication targets regardless of their position relative to the array. Analytical results reveal that the proposed antenna system can provide a channel capacity of more than 200 bits/s/Hz at a signal-to-noise power ratio (SNR) of 30 dB over the whole azimuth, which is equivalent to 20 Gbps for a bandwidth of 100 MHz. This remarkably high channel capacity is shown to be due to two significant factors; the improved directivity created by the optimum in-phase excitation and the low correlation between the subarrays due to the orthogonal alignment of the array with respect to the incident waves. Over-the-air (OTA) experiments confirm the increase in channel capacity; the proposed antenna can maintain a constant transmission rate over all azimuth angles.
Device-to-device (D2D) is increasingly becoming a prominent technology within the 5G story, portrayed as a means of offloading traffic from the core network. The ever increasing demand for vehicular traffic consumption is providing the impetus for a new architectural design that can harness the benefits of D2D for vehicular users, taking a step toward offloading vehicular traffic from the core network. We propose the notion of extending D2D for vehicular scenarios with the potential to coordinate vehicular traffic using the LTE band. Furthermore, we then extend this approach by investigating cognitive radio in synergy with a geo-location database, to exploit white spaces as a means of further offloading vehicular users. Our simulation results have shown that our approach can outperform the legacy IEEE 802.11p in terms of delay.
Previous studies have shown that single-user systems employing
n-element antenna arrays at both the transmitter and the receiver can
achieve a capacity proportional to n, assuming independent Rayleigh
fading between antenna pairs. We explore the capacity of
dual-antenna-array systems under correlated fading via theoretical
analysis and ray-tracing simulations. We derive and compare expressions
for the asymptotic growth rate of capacity with n antennas for both
independent and correlated fading cases; the latter is derived under
some assumptions about the scaling of the fading correlation structure.
In both cases, the theoretic capacity growth is linear in n but the
growth rate is 10-20% smaller in the presence of correlated fading. We
analyze our assumption of separable transmit/receive correlations via
simulations based on a ray-tracing propagation model. Results show that
empirical capacities converge to the limit capacity predicted from our
asymptotic theory even at moderate n = 16. We present results for both
the cases when the transmitter does and does not know the channel
realization
As we edge closer to the broad implementation of intelligent transportation systems, the need to extend the perceptual bounds of sensor-equipped vehicles beyond the individual vehicle is more pressing than ever. Research and standardization efforts toward V2X, or vehicle to everything, technology is intended to enable the communication of individual vehicles with both one another and supporting road infrastructure. The topic has drawn interest from a large number of stakeholders, from governmental authorities to automotive manufacturers and mobile network operators. With interest sourced from many disparate parties and a wealth of research on a large number of topics, trying to grasp the bigger picture of V2X development can be a daunting task. In this tutorial survey, to the best of our knowledge, we collate research across a number of topics in V2X, from historical developments to standardization activities and a high-level view of research in a number of important fields. In so doing we hope to provide a useful reference for the state of V2X research and development for newcomers and veterans alike.
This paper presents a spatial fading emulator for evaluating handset MIMO antennas in a cluster environment. The proposed emulator is based on Clarke's model and has the ability to control RF signals directly in spatial domain to generate an accurate radio propagation channel model, which includes both uniform and non-uniform angular power spectra (APS) in the horizontal plane. Characteristics of a propagation channel such as fading correlations, eigenvalues and MIMO channel capacities of handset antennas located in the vicinity of the emulator's ring can be evaluated. The measured results show that the fading emulator with 31 antenna probes is sufficient to evaluate fading correlation and MIMO channel capacity of handset antenna in the case of a narrow APS with the standard deviation of more than 20 degrees.
This contribution studies the channel capacity of higher order MIMO configurations. The results are based on wide band channel measurements at 2.53 GHz for a representative urban macro cell in Ilmenau, Germany. for single and dual polarized antenna elements configurations from 2×2 up to 16×16 sub channels. Furthermore the analysis is performed for two different base stations heights. Only the 2×2 dual polarized MIMO setup matches the corresponding Rayleigh results. Between the same but increasing numbers of MIMO antennas, an almost constant gap between single and dual polarized setups was found. It was also found out that the results depend on the base station height, the differences in MIMO capacity results increase while the number of antennas is increasing.
The purpose of this study is to evaluate a handset MIMO antenna under practical use conditions, involving multipath radio wave propagation and the influence of the body of the user. To this end, a Monte Carlo computer simulation has been carried out to investigate the distribution of eigenvalues and channel capacity
This paper describes an evolution and standardization trends of the wireless channel modeling activities towards IMT-Advanced. After a background survey on various channel modeling approaches is introduced, two well-known multiple-input-multiple-output (MIMO) channel models for cellular systems, namely, the 3GPP/3GPP2 Spatial Channel Model (SCM) and the IMT-Advanced MIMO Channel Model (IMT-Adv MCM) are compared, and their main similarities are pointed out. The performance of MIMO systems is greatly influenced by the spatial-temporal correlation properties of the underlying MIMO channels. Here, we investigate the spatial-temporal correlation characteristics of the 3GPP/3GPP2 SCM and the IMT-Adv MCM in term of their spatial multiplexing and spatial diversity gains. The main goals of this paper are to summarize the current state of the art, as well as to point out the gaps in the wireless channel modeling works, and thus hopefully to stimulate research in these areas.
We derive a simple generalized formula for spatial correlation and show that it provides a good approximation for spatial correlation for three very different angular energy distributions: a Gaussian angle distribution, a Laplacian angle distribution, and a uniform angular distribution. We also derive an equation for spatial correlation when the angular energy distribution is bimodal. These generalized equations are parameterized by dσ/λ where d is the distance between antennas, λ is the carrier wavelength and σ is the standard deviation of the angular energy distribution. This allows for a single curve to be used for any value of d/λ and σ. It is found that the standard deviation of the angular energy distribution or angle spread is the dominant factor for determining correlation as opposed to the specific angular energy distribution.
Cognitive vehicular communication for 5G
- S Mumtaz
- K Huq
- M Ashraf
- J Rodriguez
- V Monterio
- C Politisand