| 1. |
- Bizjajeva, Svetlana, et al.
(författare)
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Mobile positioning in MIMO system using particle filtering
- 2007
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Ingår i: 2007 IEEE 66TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5. - 1090-3038. - 9781424402632 ; , s. 792-798
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Konferensbidrag (refereegranskat)abstract
- his paper represents the results of a simulation study on positioning of a mobile unit in MIMO settings. We used two different approaches for modeling the mobile movement, combined with a simple geometrical model for the MIMO channel. Three different particle filters were implemented for the position estimation. The results show that all three filters are able to achieve estimation accuracy required by Federal Communication Commission. The dimensionality of the particle filter state space is independent of the number of antenna elements, and it is possible to increase the number of antennas and use more sophisticated channel models without changing the filtering algorithms.
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| 2. |
- Almers, Peter, et al.
(författare)
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The effect of receiver antenna array horizontal orientation on MIMO channel capacity
- 2003
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Ingår i: [Host publication title missing]. - 1090-3038. - 0780377575 ; 1, s. 34-38
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Konferensbidrag (refereegranskat)abstract
- In multiple-input multiple-output (MIMO) systems the horizontal orientation of a linear array has, in some situations a large influence on the available channel capacity. In this paper, we investigate the effect of horizontal array orientation on channel capacity, eigenvalue distribution and antenna complex correlation coefficient in such systems. We present channel measurements in an office corridor environment for a 6/spl times/6 MIMO system and compare the capacity results to those of a physical and non-physical model based on the measurements. The results show that under LOS conditions the channel capacity can vary significantly depending on the receiver array orientation in the horizontal plane.
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| 3. |
- Choi, Y S, et al.
(författare)
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Fast antenna selection algorithms for MIMO systems
- 2003
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Ingår i: IEEE 58th Vehicular Technology Conference, 2003. VTC 2003-Fall.. - 1090-3038. - 0780379543 ; 3, s. 1733-1737
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Konferensbidrag (refereegranskat)abstract
- We consider the capacity of multiple-input-multiple-output (MIMO) systems with reduced complexity. One link end uses all available antennas, while the other chooses the "best" L out of N antennas. The selection of the optimum antenna subset requires an exhaustive search of all possible combinations, involving (/sub L//sup N/) computations of determinants of size L /spl times/ L, which can become prohibitively complex. In this paper, we suggest a class of fast antenna selection algorithm that are based on the correlation or mutual information between the signals at the different antenna elements. It requires less than N/sup 2/ vector multiplications and thus leads to dramatic savings on the computation time. Its performance is very close to the optimum selection procedure: the capacity penalty is less than l bit/s/Hz for the analyzed examples. The algorithm thus offers the possibility of almost-optimum selection even in fast-changing environments.
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| 4. |
- Foroughi, Farzad, et al.
(författare)
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Low complexity channel estimation for LTE in fast fading environments for implementation on multi-standard platforms
- 2010
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Ingår i: IEEE 72ND VEHICULAR TECHNOLOGY CONFERENCE FALL 2010. - 1090-3038.
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Konferensbidrag (refereegranskat)abstract
- In this paper a number of low-complexity channel estimator structures tailored to the needs of LTE terminals have been investigated. The focus has been on the algorithms exhibiting reduced complexity while providing an acceptable level of performance. To design these estimators other factors such as interoperability with another OFDM-based standard, DVB-H, in a multi-standard environment have been taken into account. The key underlying parameter has been exploiting the pilot pattern in LTE providing the possibility of minimal filtering in time domain while exhibiting an acceptable level of performance in fast fading environments.
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| 5. |
- Hult, Tommy, et al.
(författare)
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MIMO applications for interference mitigation in multiple high altitude platform WCDMA systems
- 2009
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Ingår i: 2009 IEEE 70Th Vehicular Technology Conference Fall, Vols 1-4. - Anchorage : IEEE. - 1090-3038. ; , s. 1172-1176
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Konferensbidrag (refereegranskat)abstract
- In this paper we investigate the possibility of multiple HAP coverage of a common cell area. In particular we study the uplink system performance since it is considered as a worst case scenario. In order to obtain further enhancement (interference mitigation) we also apply space-time diversity techniques, such as Single-Input Multiple-Output (SIMO) receive diversity or Multiple-Input Multiple-Output (MIMO) diversity, to improve the spectrum reuse in the multiple HAP scenario. We will show the level of improvement using SIMO and MIMO algorithms, the practical limits on the number of HAPs and SIMO/MIMO system dimension in response to traffic demands and the type of service used.
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| 6. |
- Johanson, Mathias, et al.
(författare)
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Improving vehicle diagnostics through wireless data collection and statistical analysis
- 2007
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Ingår i: 66th IEEE Vehicular Technology Conference. - Piscataway, NJ : IEEE Communications Society. - 9781424402632 ; , s. 2184-2188
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Konferensbidrag (refereegranskat)abstract
- Collection and analysis of diagnostic data from electronic control units is of paramount importance in the automotive industry, both from a life cycle support perspective, and as a tool in the product development. For pre-series test vehicles, access to diagnostic data is crucial in order to be able to track problems as early as possible in the development process, preventing serious faults to pass undetected into production vehicles. However, systematic collection of diagnostic data from test vehicles is complicated by the fact that pre-series vehicles are frequently unavailable for diagnostic read-outs, while away on test expeditions in rural areas, or being operated by taxi companies, or being otherwise inaccessible. In response, we propose a system for wireless read-out of diagnostic data, based on an embedded system installed in the test vehicles and a server component at the automotive company. Moreover, we present a number of computer-based tools for statistical analysis of diagnostic trouble codes, to aid engineers in processing the potentially very large amount of diagnostic dataata generated by the automated collection system. We strongly believe that wireless diagnostic collection systems, in combination with statistical analysis tools, will be a key component in meeting future demands on reduced development time, while the complexity of automotive electronics continue to grow. Initial results from our pilot trials with the tools described in this paper support this claim.
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| 7. |
- Kapetanovic, Dzevdan, et al.
(författare)
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Linear Precoders for Parallell Gaussian Channels with Low Decoding Complexity
- 2011
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Ingår i: IEEE 74th Vehicular Technology Conference (VTC). - 1090-3038. ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Consider the transmission of complex-valued symbols over N parallell channels in additive white Gaussian noise. It is well known that linear precoding of the complex-valued data improves system performance (e. g. symbol error rate, information rate, MMSE, etc.) at a cost of increased decoding complexity at the receiver. This work constructs precoders that are constrained to have a decoding complexity which equals that of no precoding, while still improving the system performance significantly compared with the no precoding case. This is achieved by designing the precoder so that it precodes the complex data streams separately, by utilizing the latest result from optimal real-valued precoding, and transmitting the real and complex parts of one symbol over different antennas.
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| 8. |
- Koudouridis, Georgios P., et al.
(författare)
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On the performance of multi-radio ARQ and packet scheduling in Ambient Networks
- 2007
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Ingår i: 2007 IEEE 66TH VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5. - 9781424402632 ; , s. 1456-1460
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Konferensbidrag (refereegranskat)abstract
- In alignment to an "always best experience" scenario, we assess gains on user traffic in the context of a multi-radio access environment where heterogeneous radio technologies are integrated at link layer and users are jointly scheduled across multiple radio accesses (RAs). Such integration allows for an implementation of multi-radio transmission diversity (MRTD) which switches transmission of a user's data over the available RAs. The RA selection is based on measurements of radio link quality as reported by the radio interface. The application of an ARQ scheme utilising multiple RAs (MR-ARQ) in conjunction with MRTD provides added gains on user delay and neutralizes parts of degradations in spectral efficiency caused by reporting delays. Such multi-radio ARQ mechanism exploits the diversity across independent RAs, and results in gains in throughput over those achieved by RA-specific ARQ. MRTD when combined with MR-ARQ shows gains of up to 35% in spectral efficiency compared to the case where the radio accesses operate independently.
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| 9. |
- Lerchbaumer, Peter, et al.
(författare)
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Test environment design for wireless vehicle communications
- 2007
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Ingår i: The 66th IEEE Vehicular Technology Conference, 2007. VTC-2007 Fall. - Piscataway, NJ : IEEE Press. - 9781424402632 ; , s. 2214-2218
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Konferensbidrag (refereegranskat)abstract
- The integration of new wireless technologies with vehicle computing systems has opened the doors for new fields of applications such as intelligent transportation systems. Vehicular ad hoc networks emerge as the technical basis in solutions aiming to improve road safety and efficiency as well as driving comfort. This paper discusses different factors that influence the performance of wireless vehicle communication systems and proposes a general design for the construction of a test environment for these systems. A comprehensive list of different parameters that affect the system performance is compiled. Next, these parameters are analyzed and quantified to serve as guidelines when establishing and designing components of a suitable test environment. This test environment should provide a platform that enables researchers and engineers to identify possible bottlenecks in the network functionality as well as allowing test, assessment and verification of as many of the relevant parameters involved in the ad hoc communication as possible.
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| 10. |
- Lungaro, Pietro
(författare)
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Distributed and Centralized Mobility-Aware Caching Schemes for Collaborative Service Provision in User-Deployed Networks
- 2007
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Ingår i: 66th IEEE Vehicular Technology Conference. - 9781424402632 ; , s. 309-314
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Konferensbidrag (refereegranskat)abstract
- Opening up to public access, a collection of user-deployed APs has the potential to reduce service costs and improve user service perception, especially for delay tolerant services. However, since the individual APs composing such a network are typically owned and operated by different users, the achievable performances are likely to be limited by the lack of coordination. By adopting an Inter AP communication Protocol (IAPP) that allows APs to collaborate in exchanging messages about the information requested by potentially incoming users, the APs are capable to start caching information, even before the users reach their communication ranges. In a multi-user scenario, in which the backbone capacity limits the performances of the APs, a set of distributed backbone resource management schemes, differing in their degrees of collaboration between APs and their mobility-awareness, are proposed and evaluated in respect to both a centralized caching server solution and a non cooperative scheme. The results show that, at the cost of increased memory requirements, collaborative caching brings significant improvements to both backbone capacity utilization and average user rates, as compared to the non cooperating scheme. At the same time, we show that for a centralized server solution to outperform our collaborative caching scheme, the central server needs to have a backbone capacity comparable to sum of the capacities of the individual APs deployed in the service area.
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