Andreas Weber

Swiss Federal Institute of Sport Magglingen SFISM

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Multisite field trial for LTE and advanced concepts

IEEE Communications Magazine (2009)

Ralf Irmer Harry May Andreas Weber Volker Braun Michael Schmidt

The 3GPP LTE standard is stable now in its first release (Release 8), and the question is how good its performance is in real-world scenarios. LTE is also a good base for further innovations, but it must be proven that they offer performance advantages for the price of their complexity. This article evaluates the performance of LTE Release 8 as a baseline and advanced concepts currently in discussion such as cooperative MIMO based on system-level simulations, and measurements in the laboratory and a multisite field testbed within the EASY-C project.

Testbed

LTE Advanced

Field trial

Baseline (sea)

10.1109/mcom.2009.4785385

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Citations (88)

Multiuser transmit precoding based on outdated interference alignment

Danish Aziz Andreas Weber

Downlink closed loop transmission schemes for multi user MIMO systems are usually sensitive to delays in the feedback of channel state information (CSI). We present a novel and simple transmit precoding scheme which exploits the delayed interference state information (INTSI) and the concept of interference alignment (IA). We design the precoding such that the inter-cell interference subspace from the previous transmission is aligned at the desired receiver with the intra-cell interference subspace of the current transmission. Although the alignment is not perfect for the current transmission, we show that with the help of proper receiver design, one can minimize the leakage interference caused by outdated information and still achieve good performance. We evaluate our scheme with the help of extensive system level simulations and provide a comparison with state of the art MU-MIMO transmit precoding schemes in terms of mean user rates. The simulation results show that our proposed scheme provides considerable gains over the other transmission schemes.

Zero-forcing precoding

Channel state information

Interference Alignment

10.1109/icumt.2012.6459655

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An industrial perspective of relaying for cellular systems

Federico Boccardi Volker Braun Oliver Stanze Matthew Baker Antonia M. Tulino

In recent years, the problem of designing efficient relaying schemes has attracted much effort within the research community. However, from a practical deployment point of view, many aspects remain unclear. In this paper we endeavour to provide an industrial perspective on this problem. First, we describe the main characteristics and deployment-related aspects of relays. Second, we give an overview of the status of relaying in LTE-Advanced and present some simulation results to assess the performance of relays in various scenarios of relevance to LTE-Advanced. Finally, we discuss short-term extensions and present some long-term research issues, that, if solved, would make a significant impact on the design of future cellular networks.

Relevance

10.1109/acssc.2010.5757744

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Citations (3)

Modeling of X-pol antennas for LTE system simulation

Andreas Weber Antoni Bestard

LTE and LTE Advanced system performance evaluation is mainly done by simulations based on standardized assumptions and methodology. Multiple Input Multiple Output (MIMO) antenna systems require a spatial channel model. Important antenna types are cross-polarized antenna structures which are simulated based on a cross-polarization extension of the spatial channel model. In this paper we show some shortcomings of the widely used X-Pol channel model and we present a solution based on coordinate transformation.

10.1109/iswcs.2011.6125342

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Citations (3)

Climate Change and Long-Run Discount Rates: Evidence from Real Estate

Review of Financial Studies (2021)

Stefano Giglio Matteo Maggiori K. H. Rao Johannes Stroebel Andreas Weber

Abstract We show that housing markets provide information about the appropriate discount rates for valuing investments in climate change abatement. Real estate is exposed to both consumption and climate risk and its term structure of discount rates is downward sloping, reaching 2.6% for payoffs beyond 100 years. We use a tractable asset pricing model that incorporates features of climate change to show that the term structure of discount rates for climate-hedging investments is thus upward sloping but bounded above by the risk-free rate. At horizons at which risk-free rates are unavailable, the estimated housing discount rates provide an upper bound.

Stochastic discount factor

Consumption

10.1093/rfs/hhab032

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Citations (240)

Multichannel circuit switching-performance evaluation of switching networks

IEEE Journal on Selected Areas in Communications (1991)

Andreas Weber W. Fischer M. Huber

An approximate analytical method is presented for the estimation of the loss probability for single and multichannel calls in TST (time-space-time) switching networks. Two extended methods are described. The assumptions for the basic method are that: all occupation patterns of the two internal highways between a certain start and destination highway for a given number of occupied channels have the same probability, and that the state probabilities of the start and destination highway are given by a multidimensional Erlang distribution. Based on this method, the second approximation considers calls that are switched from start to destination highway. In a third method, the dependency of the states of all input and output highways is taken into account. The basic approximation has shown the best agreement with the simulation results. The other methods take into account additional properties of TST switching networks for single and multichannel connections. In order to keep the state space in a reasonable size, additional assumptions had to be used which impair the results significantly compared to the basic approximation method.< >

Erlang (programming language)

10.1109/49.68451

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Citations (5)

Power Optimization for Low Interference and Throughput Enhancement for 5G and 6G systems

Silvio Mandelli Alessandro Lieto Paolo Baracca Andreas Weber Thorsten Wild

While the first 5G releases have been defined, it is expected that future Beyond 5G (B5G) and 6G networks will further reduce inter-site distances between access points. Accordingly, ensuring co-existence and controlling interference in such scenarios is pivotal for the success of future wireless systems. In this work all the unused wireless time-frequency resources in non-congested cells are leveraged to propose a novel Link Adaptation (LA) scheme, whose paradigm is to maximize resource utilization and reduce transmit power as much as possible. Note that this contrasts currently considered mechanisms that simply maximize spectral efficiency, demanding power optimization with long-term updates from other procedures. The proposed scheme does not require inter-cell coordination and is transparent to other MAC procedures, making its practical implementation trivial. We analytically establish that the mechanism achieves at least the same capacity in all cells and reduces transmit power when compared to state of the art LA mechanisms. In addition, extensive 3GPP-compliant system level simulations are conducted to assess the performance of the proposal, showing substantial gains in terms of achievable cell throughput in congested cells and overall transmit power reduction.

Transmitter power output

Spectral Efficiency

Power Optimization

10.1109/wcncw49093.2021.9419981

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Citations (8)

Parameter Selection for HSDPA Iub Flow Control

Marc Necker Andreas Weber

The recently emerging high speed downlink packet access (HSDPA) enhances conventional WCDMA systems according to the UMTS standard with data rates of up to 14 MBit/s in the downlink direction. This is achieved by using adaptive modulation and coding as well as a fast hybrid automatic repeat request (HARQ) mechanism. This functionality is implemented close to the air interface in the node B. In addition to the data buffer in the RNC, this requires a second data buffer in the node B. Consequently, a flow control mechanism is needed which controls the amount of data to be transmitted from the RNC's buffer to the node B's buffer. The spatial separation of RNC and node B imposes significant signaling constraints and control dead time limitations to the flow control mechanism. Additionally, due to the time-varying nature of the radio channel, the data rate towards a particular user may be highly variable. In this paper, we study the impact of the flow control on system performance. In particular, we consider the parameter choice for a previously presented algorithm and highlight some inherent tradeoffs

UMTS frequency bands

Flow Control

Link adaptation

10.1109/iswcs.2005.1547693

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Citations (21)

Power Optimization and Throughput Enhancement in 6G Networks by Delay-Aware Resource Leverage

Silvio Mandelli Alessandro Lieto Andreas Weber Thorsten Wild

While refining the specifics of the 5G wireless standards, the research community is already shifting its attention towards new 6G paradigms, like the "network of networks" topology. In that context, the sub-networks will be pivotal to support the advances of industrial internet of things or Industry 4.0, e.g. connecting an entire group of sensors and actuators of a robot. The unprecedented access points density in 6G sub-networks requires the design of schemes that can properly manage the interference. Targeting these high density scenarios, we describe the Power Optimization for Low Interference and Throughput Enhancement (POLITE) paradigm for link adaptation and power allocation which leverages all available radio resources to stabilize and reduce the interference. The baseline link adaptation schemes are compared with POLITE in their performance in a 3GPP-calibrated system level simulator for industrial scenarios. As services in industrial environments require high reliability under constrained delays, we propose delay-aware formulations in the POLITE design. In this work the emphasis is on the algorithmic implementation and performance assessment for generic delay requirements, leaving the investigation of extreme delay requirements for future work. Simulation results prove the benefits of POLITE in terms of increased throughput and delay satisfaction, with an overall reduced transmit power compared to the current baseline link adaptation schemes.

Leverage (statistics)

Power Optimization

10.1109/eucnc/6gsummit51104.2021.9482470

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Citations (4)

Performance Prediction of CoMP in Large Cellular Systems

Cambridge University Press eBooks (2011)

Thorsten Wild Andreas Weber

While Chapter 13 has shown that various CoMP concepts discussed in this book do indeed work in practice and yield gains that match fairly well to theoretical predictions, any field trial result is of course always limited to a particular, not necessarily representative, scenario, and, more importantly, to a very limited number of terminals. Before an operator invests into the technology and infrastructure required for certain CoMP schemes, however, he will want to assess their performance in large-scale systems with a large number of mobile terminals and potentially complex traffic models.

Operator (biology)

10.1017/cbo9780511783029.014

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Citations (0)