| 181. |
- Kolmonen, V. -M., et al.
(författare)
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Dual-link capacity analysis of measured time-variant indoor radio channels
- 2010
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 46:8, s. 72-592
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Tidskriftsartikel (refereegranskat)abstract
- There has been extensive research about single link multiple-input multiple-output (MIMO) channels, both simulated and measured, but only a few studies have targeted multilink analysis with measured channel data. Hence, in this presented report, the authors analyse the influence of spatial separation of user terminals and the human shadowing effect on the MIMO capacity and on the signal-to-interference ratio in indoor radio channels.
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| 182. |
- Kolmonen, Veli-Matti, et al.
(författare)
-
Measurement-based evaluation of interlink correlation for indoor multi-user MIMO Channels
- 2010
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 9, s. 311-314
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedThe properties of the single-link multiple-input-multiple- output (MIMO) propagation channels have been analyzed in many studies based on extensive propagation measurements. In this letter, we extend the measurement-based analysis to dual-link MIMO propagation channels. Here, we examine interlink correlation by evaluating the correlation of eigenvectors obtained from multiple MIMO links. We also investigated how the physical propagation phenomena produced the interlink correlation. Results indicate that interlink correlation may exist. Sometimes it is found to be very high also for far separated receive units, depending on similarity of dominant propagation mechanisms between multiple MIMO links and also on antenna array properties.
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| 183. |
- Kuang, Yubin, et al.
(författare)
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Single Antenna Anchor-Free UWB Positioning based on Multipath Propagation
- 2013
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Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- Radio based localization and tracking usually require multiple receivers/transmitters or a known floor plan. This paper presents a method for anchor free indoor positioning based on single antenna ultra wideband (UWB) measurements. By using time of arrival information from multipath propagation components stemming from scatterers with different, but unknown, positions we estimate the movement of the receiver as well as the angle of arrival of the considered multipath components. Experiments are shown for real indoor data measured in a lecture room with promising results. Simultaneous estimation of both receiver motion, transmitter and scatterer positions is performed using an factorization based approach followed by non-linear least squares optimization. A RANSAC approach to automatic matching of data has also been implemented and tested. The resulting reconstruction is compared to ground truth motion as given by the antenna positioner. The resulting accuracy is in the order of one cm.
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| 184. |
- Kåredal, Johan, et al.
(författare)
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A geometry-based stochastic MIMO model for vehicle-to-vehicle communications
- 2009
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Ingår i: IEEE Transactions on Wireless Communications. - 1536-1276. ; 8:7, s. 3646-3657
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Tidskriftsartikel (refereegranskat)abstract
- Vehicle-to-vehicle (VTV) wireless communications have many envisioned applications in traffic safety and congestion avoidance, but the development of suitable communications systems and standards requires accurate models for the VTV propagation channel. In this paper, we present a new wideband multiple-input-multiple-output (MIMO) model for VTV channels based on extensive MIMO channel measurements performed at 5.2 GHz in highway and rural environments in Lund, Sweden. The measured channel characteristics, in particular the non-stationarity of the channel statistics, motivate the use of a geometry-based stochastic channel model (GSCM) instead of the classical tapped-delay line model. We introduce generalizations of the generic GSCM approach and techniques for parameterizing it from measurements and find it suitable to distinguish between diffuse and discrete scattering contributions. The time-variant contribution from discrete scatterers is tracked over time and delay using a high resolution algorithm, and our observations motivate their power being modeled as a combination of a (deterministic) distance decay and a slowly varying stochastic process. The paper gives a full parameterization of the channel model and supplies an implementation recipe for simulations. The model is verified by comparison of MIMO antenna correlations derived from the channel model to those obtained directly from the measurements.
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| 185. |
- Kåredal, Johan, et al.
(författare)
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A measurement-based fading model for wireless personal area networks
- 2008
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Ingår i: IEEE Transactions on Wireless Communications. - 1536-1276. ; 7:11, s. 4575-4585
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Tidskriftsartikel (refereegranskat)abstract
- Personal area networks (PANs) are wireless communications systems with high data rates but small coverage area. PAN propagation channels differ from the well-explored propagation channels of wide-area networks due to several reasons: (i) the distances are typically very small, (ii) the antenna arrangements can be quite different, and (iii) the influence from human presence in the environment is different. The current paper presents results of a channel measurement campaign, where measurements are conducted over distances of 1-10 m using several multi-antenna devices, combined to create different PAN scenarios. For each measured Tx-Rx separation, channel realizations are obtained by small spatial movements of the antenna devices, and by rotating the persons holding the devices. From the results, we draw two main conclusions: (i) The small-scale amplitude statistics, analyzed as the variations over a small sampling area and frequency subchannels, cannot be described in a satisfactory way using only the Rayleigh or Ricean distributions, rather a mixed distribution, the generalized gamma distribution, is more suitable; (ii) it is advantageous to distinguish between two types of large-scale fading: body shadowing (due to the orientation of the person holding the device) and shadowing due to surrounding objects (lateral movement). We also define and parameterize a complete statistical model for all fading.
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| 186. |
- Kåredal, Johan, et al.
(författare)
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A measurement-based statistical model for industrial ultra-wideband channels
- 2007
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Ingår i: IEEE Transactions on Wireless Communications. - 1536-1276. ; 6:8, s. 3028-3037
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Tidskriftsartikel (refereegranskat)abstract
- The results of three ultra-wideband (UWB) measurement campaigns conducted in two different industrial environments are presented. A frequency range of 3.1 - 10.6 or 3.1 - 5.5 GHz was measured using a vector network analyzer and a virtual array technique enabling the investigation of smallscale statistics. The results show that the energy arrives in clusters, and that the abundance of metallic scatterers present in the factory hall causes dense multipath scattering. The latter produces a small-scale fading that is mostly Rayleigh distributed; the only exception being the delay bin containing the line-of-sight component. The power delay profile can be modeled by a generalized Saleh-Valenzuela model, where different clusters have different ray power decay constants. It is also noted that the number of multipath components required to capture a majority of the energy is quite large. More than a hundred components can be needed to capture 50% of the total available energy.
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| 187. |
- Kåredal, Johan, et al.
(författare)
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A MIMO channel model for wireless personal area networks
- 2010
-
Ingår i: IEEE Transactions on Wireless Communications. - 1536-1276. ; 9:1, s. 245-255
-
Tidskriftsartikel (refereegranskat)abstract
- Recent years have seen an increasing attention given to wireless Personal Area Networks (PANs), which are typically networks with small transmitter-receiver (TX-RX) separation. The desire for high data rates has led to an interest in deploying multiple-input multiple-output (MIMO) transmission for such systems, but up until this date there exists, to the authors’ best knowledge, no MIMO channel model that enables performance simulations of such systems. An important characteristic of PANs, and at the same time an important difference to regular wireless local area networks, is the interaction between the antenna array and the user. In conjunction with the irregular antenna arrangements that are typical for PAN devices, this has been shown to lead to flexible channel statistics. In this paper we present a MIMO model for PANs that incorporates these effects by prescribing different small-scale statistics and path gains to different antenna elements. The proposed model can thus be seen as a generalization of the classical MIMO model for LOS situations. The model is compared to several sets of measurement data and found to provide a very good description of the essential PAN channel characteristics. We also provide a detailed parameterization of the model for a particular PAN scenario.
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| 188. |
- Kåredal, Johan, et al.
(författare)
-
Characterization of a computer board-to-board ultra-wideband channel
- 2007
-
Ingår i: IEEE Communications Letters. - 1089-7798. ; 11:6, s. 468-470
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we present the results of an extensive ultra-wideband (UWB) measurement campaign performed inside the chassis of two desktop computers. The purpose of the campaign is to analyze the possibility of board-to-board communications, replacing cable connections. Measurements of the propagation channel are performed over a frequency range of 3.1 - 10.6 GHz using a vector network analyzer and antennas small enough to enable integration on a circuit board. The results show that the propagation environment is very uniform, with small variations in the path gain between different positions within a computer. We also performed interference measurements, showing that the interference is restricted to certain subbands.
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| 189. |
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| 190. |
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