| 161. |
- Hersyandika, Rizqi, et al.
(författare)
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Measurement-based blockage and intra-cluster interference analysis in mmWave multi-point connectivity networks
- 2022
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Ingår i: EmergingWireless 2022 - Proceedings of the 1st International Workshop on Emerging Topics in Wireless, Part of CoNEXT 2022. - New York, NY, USA : ACM. - 9781450399340 ; , s. 12-17
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Konferensbidrag (refereegranskat)abstract
- Millimeter-wave (mmWave) is one key enabler for high data rates in (beyond-)5G wireless communication networks. The use of directive beams and the shorter transmission range in mmWave communications make it easily obstructed or blocked by humans in dynamic real-world scenarios. Connectivity diversity, a solution to link disruption and blockage, could be achieved by deploying distributed multi-point infrastructure. To this end, a mmWave User Equipment (UE) requires a multi-reception capability. This paper investigates how different multi-point connectivity schemes, established by a set of non-cooperative and cooperative serving Base Stations (BSs), perform in the ideal Line-of-Sight (LoS) and the worst-case blocked scenarios. The results and analysis found that the impact of intra-cluster interference on spectral efficiency is much more significant than the blockage. Without any interference cancellation, regardless of LoS or blocked scenarios, adding extra serving BSs does not necessarily improve the spectral efficiency due to the dominant inter-stream interference within a cluster of services.
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| 162. |
- Hoeher, Peter, et al.
(författare)
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Channel estimation with superimposed pilot sequence
- 1999
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Ingår i: Proc. IEEE GLOBECOM '99, Rio de Janeiro, Brazil, December 1999. - 0780357965 ; 4, s. 2162-2166
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Konferensbidrag (refereegranskat)abstract
- For the purpose of various synchronization tasks (including carrier phase, time, frequency, and frame synchronization), one may add a known pilot sequence, typically a pseudo-noise sequence, to the unknown data sequence. This approach is known as a spread-spectrum pilot technique or as a superimposed pilot sequence technique. In this paper, we apply the superimposed pilot sequence technique for the purpose of channel estimation (CE). We propose and verify a truly coherent receiver based on the Viterbi algorithm, which is optimal in the sense of per-survivor processing. We also suggest a generic low-cost receiver structure based on reduced-state sequence estimation. Among the distinct advantages compared to conventional pilot-symbol-assisted CE are (i) a lack of bandwidth expansion and (ii) a significantly improved performance in fast fading environments. The proposed Viterbi receiver may also be used as an alternative receiver for pilot-symbol-assisted CE
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| 163. |
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| 164. |
- Hofer, Markus, et al.
(författare)
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Real-Time Geometry-Based Wireless Channel Emulation
- 2018
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Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545.
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Tidskriftsartikel (refereegranskat)abstract
- Connected autonomous vehicles and industry 4.0 productions scenarios require ultra-reliable low-latency communication links. The varying positions of transmitter, reflecting objects and receiver cause a non-stationary time- and frequency-selective fading process. In this paper, we present the necessary hardware architecture and signal processing algorithms for a real-time geometry-based channel emulator, that is needed for testing of wireless control systems. We partition the non-stationary fading process into a sequence of local stationarity regions and model the channel impulse response as sum of propagation paths with time-varying attenuation, delay and Doppler shift. We implement a subspace projection of the propagation path parameters, to compress the time-variant channel impulse response. This enables a low data-rate link from the host computer, which computes the geometry-based propagation paths, to the software defined radio (SDR) unit, that implements the convolution on a field programmable gate array (FPGA). With our new architecture, the complexity of the FPGA implementation becomes independent of the number of propagation paths. Our channel emulator can be parametrized by all known channel models. Without loss of generality we use a parameterization by a geometry-based stochastic channel model (GSCM), due to its non-stationary nature. We provide channel impulse response measurements of the channel emulator, using the RUSK Lund channel sounder for a vehicular scenario with 617 propagation paths. A comparison of the time-variant power delay proflie (PDP) and Doppler spectral density (DSD) of simulated and emulated channel impulse response showed a close match with an error smaller than -35 dB. The results demonstrate that our channel emulator is able to accurately emulate non-stationary fading channels with continuously changing path delays and Doppler shifts.
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| 165. |
- Hofer, Markus, et al.
(författare)
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Validation of a Real-Time Geometry-Based Stochastic Channel Model for Vehicular Scenarios
- 2018
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Ingår i: 2018 IEEE 87th Vehicular Technology Conference, VTC Spring 2018 - Proceedings. - 2577-2465. - 9781538663554 ; 2018-June, s. 1-5
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Konferensbidrag (refereegranskat)abstract
- The performance of wireless communication systems is fundamentally determined by wireless communication channel properties. Wireless vehicular communication channels exhibit multipath propagation and non-stationary channel statistics. Methods and tools for the repeatable test of wireless communication systems and signal processing algorithms in such environments are urgently needed to enable the development of reliable communication links with low-latency. In this paper we present the measurement and validation of a real time channel emulation method for non-stationary vehicular scenarios based on a geometry-based stochastic channel model.
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| 166. |
- Hult, Tommy, et al.
(författare)
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Analytical dual-link MIMO channel model using correlated correlation matrices
- 2010
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Ingår i: Proceedings of the Fourth European Conference on Antennas and Propagation. - 9781424464319 - 9788476534724
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Konferensbidrag (refereegranskat)abstract
- Analytical Multiple-Input Multiple-Output (MIMO) models are often attractive due to their low complexity when analyzing possibilities and limitations in the system. In this paper we outline a a possible dual link extension of an analytical MIMO channel model and investigate its suitability based on measurements of a dual link MIMO scenario. The extension is based on the correlation matrix distance (CMD) as a gauge to generate correlation matrices for the additional links of the multi-link scenario.
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| 167. |
- Ji, Yilin, et al.
(författare)
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Virtual Drive Testing Over-the-Air for Vehicular Communications
- 2020
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Ingår i: IEEE Transactions on Vehicular Technology. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-9545 .- 1939-9359. ; 69:2, s. 1203-1213
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Tidskriftsartikel (refereegranskat)abstract
- Multiple-input multiple-output (MIMO) over-the-air (OTA) testing is a standardized procedure to evaluate the performance of MIMO-capable devices such as mobile phones and laptops. With the growth of the vehicle-to-everything (V2X) service, the need for vehicular communication testing is expected to increase significantly. The so-called multi-probe anechoic chamber (MPAC) setup is standardized for MIMO OTA testing. Typically, a test zone of 0.85 wavelength in diameter can be achieved with an 8-probe MPAC setup, which can encompass device-under-test (DUT) of small form factors. However, a test zone of this size may not be large enough to encompass DUTs such as cars. In this article, the sufficient number of OTA probes for the MPAC setup for car testing is investigated with respect to the emulation accuracy. Our investigation shows that the effective antenna distance of the DUT is more critical than its physical dimensions to determine the required number of OTA probes. In addition, throughput measurements are performed under the standard SCME UMa and UMi channel models with the 8-probe MPAC setup and the wireless cable setup, i.e. another standardized testing setup. The results show reasonably good agreement between the two setups for MIMO OTA testing with cars under the standard channel models.
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| 168. |
- Jiang, Fan, 1987-, et al.
(författare)
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Low-complexity Channel Estimation and Localization with Random Beamspace Observations
- 2023
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Ingår i: ICC 2023 - IEEE International Conference on Communications. - Piscataway, NJ : IEEE. - 9781538674628 ; 2023-May, s. 5985-5990
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Konferensbidrag (refereegranskat)abstract
- We investigate the problem of low-complexity, high-dimensional channel estimation with beamspace observations, for the purpose of localization. Existing work on beamspace ESPRIT (estimation of signal parameters via rotational invariance technique) approaches requires either a shift-invariance structure of the transformation matrix, or a full-column rank condition. We extend these beamspace ESPRIT methods to a case when neither of these conditions is satisfied, by exploiting the full-row rank of the transformation matrix. We first develop a tensor decomposition-based approach, and further design a matrix-based ESPRIT method to achieve auto-pairing of the channel parameters, with reduced complexity. Numerical simulations show that the proposed methods work in the challenging scenario, and the matrix-based ESPRIT approach achieves better performance than the tensor ESPRIT method. © 2023 IEEE
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| 169. |
- Johansson, Anders J, et al.
(författare)
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MIMO channel measurements for personal area networks
- 2005
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Ingår i: [Host publication title missing]. - 1550-2252. - 0780388879 ; 61:1, s. 171-176
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Konferensbidrag (refereegranskat)abstract
- This paper analyzes MIMO propagation channels for personal area networks. Such channels show important differences to propagation channels in wide-area networks, due to the different environments in which the systems are operated, as well as due to different mobility models, ranges, and presence of humans in the environment, and the impact of the antenna arrangement. We present results from a recent measurement campaign for this type of channel. We first analyze the requirements for measurement setups, especially in terms of different positions and orientations of the antenna arrays, to obtain meaningful results. We then analyze the measured data and present results for path loss, power delay profiles, spatial correlation and temporal correlation.
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| 170. |
- Khan, Muhammad Gufran, et al.
(författare)
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Measurements and Analysis of UWB Channels in Industrial Environments
- 2005
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Konferensbidrag (refereegranskat)abstract
- Communication in industrial environments is an important scenario for ultra wideband (UWB) systems. The characteristics of this environment differ considerably from office environments, where most of the channel measurements reported in the literature are performed. In this paper, we present the results and analysis of UWB channel measurements in an industrial environment. We investigate both peer-to-peer non-line-of-sight (P-P NLOS) and base station NLOS (BS NLOS) scenarios. The measurements are performed in the frequency range 3.1 to 8 GHz, at distances 2-16 m, using a vector network analyzer in conjunction with virtual antenna arrays. From these measurements, we extract channel model parameters such as power delay profiles, pathloss exponents, rms delay spread and the percentage of energy captured by RAKE receivers with a finite number of fingers. In addition, Saleh- Valenzuela parameters such as ray and cluster power decay constants and distribution of cluster interarrival times are extracted.
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