| 1. |
- Alonso, Arrate, et al.
(författare)
-
Capacity evaluation of measured vehicle-to- vehicle radio channels at 5.2 GHz
- 2010
-
Konferensbidrag (refereegranskat)abstract
- Reliability in Ricean multiple-input-multipleoutput (MIMO) channels is crucial for safety-related vehicle-tovehicle (V2V) applications. In Ricean channels, there is a signalto- noise ratio-dependent critical data rate below which signaling with zero outage is possible. The link will be more reliable the higher this critical data rate is. We present results of spectral efficiency and outage probability from channel sounder measurements of V2V MIMO radio channels in the 5.2 GHz band. Our results show that MIMO channels with higher spatial correlation lead to lower ergodic capacity and a reduced critical data rate. However, for fixed output power the temporal evolution of the ergodic capacity and critical data rate shows that the channel with the strongest line of sight (LoS) component also has the highest capacity.
|
|
| 2. |
- Alonso, Arrate, et al.
(författare)
-
Temporal evolution of channel capacity in vehicular MIMO channels in the 5 GHz band
- 2010
-
Ingår i: EMTS 2010: 2010 URSI International Symposium on Electromagnetic Theory. - 9781424451548 - 9781424451531 ; , s. 938-941
-
Konferensbidrag (refereegranskat)abstract
- Reliability in Ricean multiple-input-multiple-output (MIMO) channels is crucial for safety related vehicle-tovehicle (V2V) applications. Due to the time variability of vehicular communication channel, it is very significant to study the temporal evolution of channel characterization criteria. We present evaluation results of the temporal evolution of the spectral efficiency from channel sounder measurements of vehicle-to-vehicle MIMO radio channels in the 5.2 GHz band. Our results show that MIMO channels with higher spatial correlation lead to lower ergodic capacity and a reduced signalto- noise ratio-dependent critical data rate. The temporal evolution of the ergodic capacity and critical data rate shows that the channel with the strongest line of sight (LoS) component also has the highest capacity. We also present a detailed analysis of the environmental factors affecting the capacity pattern throughout the measurement run. Dynamic scatterers introduce capacity bursts instantaneously; the trend stays congruent with the theory.
|
|
| 3. |
- Bernadó, Laura, et al.
(författare)
-
In-tunnel vehicular radio channel characterization
- 2011
-
Ingår i: [Host publication title missing]. - 1550-2252. - 9781424483327
-
Konferensbidrag (refereegranskat)abstract
- Abstract in UndeterminedInside a tunnel, electromagnetic wave propagation differs strongly from the well understood "open-air" situation. The characterization of the tunnel environment is crucial for deploying vehicular communication systems. In this paper we evaluate vehicle-to-vehicle (V2V) radio channel measurements inside a tunnel. We estimate the time-varying root mean square (rms) delay and Doppler spreads, as well as the excess delay and the maximum Doppler dispersion. The fading process in V2V communications is inherently non-stationary. Hence, we characterize the stationarity time, for which we can consider the fading process to be wide sense stationary. We show that the spreads, excess delay, and maximum Doppler dispersion are larger on average when both vehicles are inside the tunnel compared to the "open-air" situation. The temporal evolution of the stationarity time is highly influenced by the strength of time-varying multipath components and the distance between vehicles. Furthermore, we show the good fit of the rms delay and Doppler spreads to a lognormal distribution, as well as for the stationarity time. From our analysis we can conclude that the IEEE 802.11p standard will be robust towards inter-symbol and inter-carrier interference inside a tunnel.
|
|
| 4. |
- Bernadó, Laura, et al.
(författare)
-
Multi-dimensional K-factor analysis for V2V radio channels in open sub-urban street crossings
- 2010
-
Ingår i: [Host publication title missing]. - 9781424480173 ; , s. 58-63
-
Konferensbidrag (refereegranskat)abstract
- In this paper we analyze the small-scale fading statistics for vehicle-to-vehicle (V2V) communications in a typical open sub-urban street crossing. The two cars approach the crossing from two different streets and the channel conditions vary from non line-of sight (NLOS) to line-of-sight (LOS). The small-scale fading of the first delay bin is Ricean distributed with a time-varying K-factor. The later delay bins are mostly Rayleigh distributed. The antenna arrays used for recording the multiple-input multiple-output channels are linear and consist of 4 elements with directional radiation patterns. We investigate the K-factor variation of the first delay bin in time, frequency, and space dimensions, where the measurement has a duration of 20 s, a bandwidth of 240 MHz, and 16 individual single-input single- output channels. We observe that the large/small K-factor values are not necessarily correlated with the received power. We show that the K-factor can not be assumed to be constant in any of the considered domains, not even in the frequency domain, as it has been always done for relative bandwidths up to 10%. The narrow- band K-factor for each frequency bin corroborates the need to consider its frequency variation. The antenna radiation patterns, and the illuminated objects by them at different time instances are the cause of these variations. We conclude that a multi- dimensional varying K-factor models the large-scale statistical behaviour more accurately than a constant K-factor.
|
|
| 5. |
- Bernadó, Laura, et al.
(författare)
-
Non-WSSUS Vehicular Channel Characterization at 5.2 GHz - Spectral Divergence and Time-Variant Coherence Parameters
- 2008
-
Konferensbidrag (refereegranskat)abstract
- The scattering environment in vehicle-to-vehicle communication channels at 5.2 GHz changes rapidly. Hence the wide-sense stationary (WSS) uncorrelated scattering (US) assumption for the fading process is valid for short time intervals only. We characterize the spectral divergence of the local scattering function (LSF) sequence in order to assess the non-WSSUS characteristics in different scenarios. We find that the vehicle-to-vehicle channels violate the wide-sense stationarity much stronger than the US assumption. Additionally, we use the LSF to quantify the time dependence of the channel coherence time and bandwidth. Both parameters vary strongly over time depending on the chosen scenario. Furthermore the effect of the antenna radiation pattern on the fading process is quantified, which can cause the strength of a multipath component to change by more than 40 dB in drive-by experiments.
|
|
| 6. |
- Bernado, Laura, et al.
(författare)
-
Vehicular Channels
- 2012
-
Ingår i: LTE-Advanced and Next Generation Wireless Networks: Channel Modelling and Propagation. - : Wiley. - 9781119976707 ; , s. 153-186
-
Bokkapitel (refereegranskat)
|
|
| 7. |
- Czink, Nicolai, et al.
(författare)
-
General discussion
- 2012
-
Ingår i: Faraday Discussions. - 1359-6640. ; 158, s. 239-266
-
Tidskriftsartikel (refereegranskat)
|
|
| 8. |
- Czink, Nicolai, et al.
(författare)
-
Tracking time-variant cluster parameters in MIMO channel measurements: algorithm and results
- 2007
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a joint clustering-and-tracking framework to identify time-variant cluster parametersfor geometry-based stochastic MIMO channel models.The method uses a Kalman filter for tracking and predicting cluster positions, a novel consistentinitial guess procedure that accounts for predicted cluster centroids, and the well-known KPower-Means algorithm for cluster identification.We tested the framework by applying it to three entirely different sets of MIMO channel measurementdata obtained by different channel sounders: indoor measurements conducted at 2.55GHz, outdoor rural measurements at 300 MHz, and outdoor sub-urban measurements at 2.0 GHz.The time-variant cluster parameters of interest are: (i) cluster movement, (ii) change of clusterspreads, (iii) cluster lifetimes, and birth and death rates of cluster.We find that clusters show significant movement in parameter space depending on the environment.The spreads of individual clusters change rather randomly over their lifetime, with astandard deviation up to 150% of their mean spread. The cluster lifetime is approximately exponentiallydistributed, however additionally one has to account for long-living clusters coming fromthe line-of-sight path or from major reflectors.
|
|
| 9. |
- Gan, Mingming, et al.
(författare)
-
Modeling time-variant fast fading statistics of mobile peer-to-peer radio channels
- 2011
-
Ingår i: [Host publication title missing]. - 1550-2252. - 9781424483327
-
Konferensbidrag (refereegranskat)abstract
- Abstract in UndeterminedThe radio channels between nodes of an indoor peer-to-peer network show specific fast fading characteristics. Depending on the mobility and on the scattering properties of the environment, different kinds of fading distributions can occur: Ricean fading between static nodes, but also Rayleigh or even double-Rayleigh fading between mobile nodes. We investigate fast fading in indoor peer-to-peer networks based on radio channel measurements. It turns out that the fading statistics change over time. While the predominant fading mechanism is a combination of Rayleigh and double-Rayleigh fading, Ricean fading also occasionally occurs. On top of that, indoors, the statistics of the fast fading change over time even for small-motions of the nodes, since the propagation environment is inhomogeneous. We comprehensively model these effects using a hidden Markov model, parameterized from our measurements. The model is validated, revealing a convincing fit between the model and the measurements.
|
|
| 10. |
- Kåredal, Johan, et al.
(författare)
-
A geometry-based stochastic MIMO model for vehicle-to-vehicle communications
- 2009
-
Ingår i: IEEE Transactions on Wireless Communications. - 1536-1276. ; 8:7, s. 3646-3657
-
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.
|
|
