Publikationen von Professorinnen und Professoren der HAW Hamburg
2017  
Tagungs/Konferenz/Katalogbeiträge:  

Model predictive ideal harmonic and reactive power compensation for fixed frequency in distribution grids
HSU Hamburg
NEIS Conference


2016  
Zeitschriftenbeiträge:  
Doppler Ultrasound Triggering for Cardiovascular MRI iat 3 Tesla in a Healthy Volunteer Study
MRMS20150104R2 Magnetic Resonance in Medical Sciences,
21
März
2016


Tagungs/Konferenz/Katalogbeiträge:  
Green Cellular Demand Control with Userintheloop Enabled by Smart Data Pricing using an Effective Quantum (eBit) Tariff
Vehicular Technology Conference
Montreal
18.09.2016
IEEE Vehicular Technology Conference (VTC2016Fall)
IEEE
englisch
Schlüsselwörter: Green demand control, smart data pricing, userin theloop, usagebased pricing Zusammenfassung: Mobile communications demand for data grows almost twofold every year and cellular capacity cannot catch up with this in every location and at every point in time. Not only will congestion situations appear more frequently and severely, but also every increase of data transmitted and every new infrastructure point rolled out in order to catch up with that demand is going to consume more total power. One approach towards greener communication is to reduce the actual demand. While technical solutions on Open Systems Interconnection (OSI) layers 1 trough 7 are already being exploited, layer 8, the user, is the original cause of the exploding demand. It is naive to assume that all data is equally important and valuable. Userintheloop (UIL) is a paradigm which can exactly hook in at this point, and it suggests to postpone, relocate, abandon or offload less urgent demand by immediate feedback and strong incentives like discounts and penalties in certain situations (in case of congestion). In particular, this means dynamic prices depending on time, location, and congestion (load) status, similar to smart grid for electricity utilities. Accounting and billing with dynamic prices, valueadded services, and smart data pricing can be a challenge, and such accounting and billing are utterly incompatible with the flatrate (allyoucanconsume) concept. However, cellular customers are involuntarily locked into contracts, but it is the current practice in the market, which is not in accordance with the free market spirit. Flatrate plans are practically dead, but those still luring with this name, while having caps on the maximum allowance, sell fixedvolume packages under a smoother name instead. Ultimately, we need to reestablish usagebasedpricing as a fairer and more favourable way of charging. In this paper we motivate the dynamic pricing of UIL and the upcoming new need for usagebased tariffs. We compare a few statusquo tariff plans with our novel effective quantum (eBit) tariff, which is a usagebased pricing that maps multiple usage dimensions into only one metric, eBits. The eBits will be charged for with one constant unit price dollars/eBit to give the monthly bill. All Quality of Service (QoS), application, and timedependent dynamic pricing factors are integrated into the effective quantum, so that a user can easily understand his current consumption and the bill upto that point in time. Price differentiation per QoS class is easy with constant scaling factors. %This enables smart data pricing to be easily understood by the consumers. This principle can be extended to any other chargeable metric such as kWh of electricity and m^3 of water. This ultimately enables going greener and training awareness of all consumers. 

Plakate:  
"ELFE^TM  ELearning mit FeedbackElementen in der Technischen Mechanik"
PosterBeitrag im Rahmen der 11. Ingenieurpädagogischen Regionaltagung 2016  Technische Bildung im Spannungsfeld zwischen beruflicher und akademischer Bildung  Die Vielfalt der Wege zu technischer Bildung  23.25. Juni 2016  Technische Universität Hamburg
Juni
2016
Deutsch
Schlüsselwörter: BlendedLearning, ELearning, Gamification, Simulation, FFELFE 

2015  
Zeitschriftenbeiträge:  
HetHetNets: Heterogeneous traffic distribution in heterogeneous wireless cellular networks
Journal on Selected Areas in Communications, Special Issue on Recent Advances in Heterogeneous Cellular Networks,
33(10):22522265
1
Oktober
2015
Zusammenfassung: ABSTRACT: A recent approach in modeling and analysis of the supply and demand in heterogeneous wireless cellular networks has been the use of two independent Poisson point processes (PPPs) for the locations of base stations (BSs) and user equipments (UEs). This popular approach has two major shortcomings. First, although the PPP model may be a fitting one for the BS locations, it is less adequate for the UE locations mainly due to the fact that the model is not adjustable (tunable) to represent the severity of the heterogeneity (nonuniformity) in the UE locations. Besides, the independence assumption between the two PPPs does not capture the oftenobserved correlation between the UE and BS locations. This paper presents a novel heterogeneous spatial traffic modeling which allows statistical adjustment. Simple and nonparameterized, yet sufficiently accurate, measures for capturing the traffic characteristics in space are introduced. Only two statistical parameters related to the UE distribution, namely, the coefficient of variation (the normalized secondmoment), of an appropriately defined interUE distance measure, and correlation coefficient (the normalized crossmoment) between UE and BS locations, are adjusted to control the degree of heterogeneity and the bias towards the BS locations, respectively. This model is used in heterogeneous wireless cellular networks (HetNets) to demonstrate the impact of heterogeneous and BScorrelated traffic on the network performance. This network is called HetHetNet since it has two types of heterogeneity: heterogeneity in the infrastructure (supply), and heterogeneity in the spatial traffic distribution (demand). 

Userintheloop for hethetnets with backhaul capacity constraints
IEEE Transactions on Wireless Communications,
1
Oktober
2015
english
Schlüsselwörter: wireless networks, stochastic geometry, user in the loop Zusammenfassung: ABSTRACT: A popular method to model heterogeneous networks is the use of two independent homogeneous Poisson point processes to locate UEs and BSs with unlimited backhaul capacity. Despite the analytical tractability, this approach is far from accurate. First, the distribution of UEs in real scenarios is neither homogeneous nor independent of BSs. Besides, the assumption of unlimited capacity for backhaul connections is optimistic, especially in the future 5G HetNets with small cells. In this article, we propose a novel modeling approach for heterogeneous networks with heterogeneous spatial traffic distribution (HetHetNets). Specifically, in the proposed model, a particular ratio of UEs are collocated with the BSs while the rest of UEs are independently and homogeneously distributed in the network. Moreover, the proposed model presumes backhaul connections with constrained capacity. We study the impact of this more realistic network modeling on the effectiveness of the spatial userintheloop (UIL) schemes in HetHetNets. Spatial UIL assumes that (some) UEs can be influenced by the operator to move in the network. Finally, we propose a new objective for the UIL mechanism that takes into account the impact of the BS loads and the backhaul capacities on the network performance. 

Joint realtime and nonrealtime flows, packet scheduling and resource block allocation in wireless OFDMA networks
IEEE Transactions on Vehicular Technology,
(99)
23
April
2015
ISSN: 00189545
Zusammenfassung: In this paper, we consider joint realtime (RT) and nonrealtime (NRT) flows packet scheduling and resource block (RB) allocation in orthogonal frequency division multiple access (OFDMA) wireless networks. Radio resource blocks (RB)s in OFDMA plane are to be distributed among RT and NRT flows. In the conventional approach, RT and NRT flows are served sequentially. This sequential approach is inefficient, because an RT flow may presumably have enough time until its delay deadline while its channel is in deep fade. In this situation, the transmission of NRT flows with higher level of efficiency can be performed. Intuitively speaking, the conventional sequential approach is too conservative that can be reengineered. We propose a novel joint RT and NRT flows disutilitybased packet scheduling and RB allocation, in a common pool of RBs. The proposed joint approach enlarges the effective capacity of the associated wireless system, when compared to the separated pool of RBs. The joint approach is particularly relevant for improving voiceoverLTE (VoLTE). We use mean bitrate, mean queue length, and instantaneous queuing delay information, in addition to channel information, to match the demand and supply. Furthermore, we develop a novel model for inputoutput bitrate behaviour of the mixture of RT and NRT flows. This model sheds light to identifying different load regions and understanding of the system in an intuitive manner. Our approach and methodology can be extended for broader qualityofservice requirements and for the utilities of the future applications. Simulation results show that the proposed framework is able to unify the serving mechanism of the the RT and NRT flows and is able to achieve higher admissible bitrate when handling mixed RT and NRT flows compared to various baselines. 

Optimized distributed intercell interference coordination scheme using projected subgradient and network flow optimization
IEEE Transactions on Communications,
63(1):107124
1
Januar
2015
DOI: arXiv:1410.8633
Zusammenfassung: ABSTRACT: In this paper, we tackle the problem of multicell resource scheduling, where the objective is to maximize the weighted sumrate through intercell interference coordination (ICIC). The blanking method is used to mitigate the intercell interference, where a resource is either used with a predetermined transmit power or not used at all, i.e., blanked. This problem is known to be strongly NPhard, which means that it is not only hard to solve in polynomial time, but it is also hard to find an approximation algorithm with guaranteed optimality gap. In this work, we identify special scenarios where a polynomialtime algorithm can be constructed to solve this problem with theoretical guarantees. In particular, we define a dominant interference environment, in which for each user the received power from each interferer is significantly greater than the aggregate received power from all other weaker interferers. We show that the strongly NPhard problem can be tightly relaxed to a linear programming problem in a dominant interference environment. Consequently, we propose a polynomialtime distributed algorithm that is based on the primaldecomposition, the projectedsubgradient, and the network flow optimization methods. In comparison with baseline schemes, simulation results show that the proposed scheme achieves higher gains in aggregate throughput, celledge throughput, and outage probability. 

Doppler Ultraschall im Vergleich zu Elektrokardiogramm und Pulsoximetrie bei 3T
Fortschr Röntgenstr 2015,
2015


Konferenz, Symposium, Vortragsreihe, Einzelausstellung, Modenschau, Künstl. Leitung (als Ausrichter):  
Load balancing in cellular networks with userintheloop: A spatial traffic shaping approach
IEEE International Conference on Communications (ICC)
London
8–12 June 2015
Proceedings of the IEEE International Conference on Communications (ICC)
