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Publikationen von Professorinnen und Professoren der HAW Hamburg

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Meisam Mirahsan, Rainer Schoenen und Halim Yanikomeroglu
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):2252-2265
1 Oktober 2015

Marker: IuE

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 (non-uniformity) in the UE locations. Besides, the independence assumption between the two PPPs does not capture the often-observed correlation between the UE and BS locations. This paper presents a novel heterogeneous spatial traffic modeling which allows statistical adjustment. Simple and non-parameterized, 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 second-moment), of an appropriately defined inter-UE distance measure, and correlation coefficient (the normalized cross-moment) 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 BS-correlated 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).

Meisam Mirahsan, Rainer Schoenen, Halim Yanikomeroglu, Gamini Senarath und Ngoc Dung-Dao
User-in-the-loop for hethetnets with backhaul capacity constraints
IEEE Transactions on Wireless Communications,
1 Oktober 2015

Schlüsselwörter: wireless networks, stochastic geometry, user in the loop

Marker: IuE

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 user-in-the-loop (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.

Alireza Sharifian, Rainer Schoenen und Halim Yanikomeroglu
Joint realtime and non-realtime flows, packet scheduling and resource block allocation in wireless OFDMA networks
IEEE Transactions on Vehicular Technology, (99)
23 April 2015
ISSN: 0018-9545

Marker: EuI

Zusammenfassung: In this paper, we consider joint realtime (RT) and non-realtime (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 disutility-based 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 voice-over-LTE (VoLTE). We use mean bit-rate, 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 input-output bit-rate 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 quality-ofservice 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 bit-rate when handling mixed RT and NRT flows compared to various baselines.

Akram Bin Sediq, Rainer Schoenen, Halim Yanikomeroglu und Gamini Senarath
Optimized distributed inter-cell interference coordination scheme using projected subgradient and network flow optimization
IEEE Transactions on Communications, 63(1):107-124
1 Januar 2015

Marker: EuI

Zusammenfassung: ABSTRACT: In this paper, we tackle the problem of multi-cell resource scheduling, where the objective is to maximize the weighted sum-rate through inter-cell interference coordination (ICIC). The blanking method is used to mitigate the inter-cell 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 NP-hard, 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 polynomial-time 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 NP-hard problem can be tightly relaxed to a linear programming problem in a dominant interference environment. Consequently, we propose a polynomial-time distributed algorithm that is based on the primal-decomposition, the projected-subgradient, and the network flow optimization methods. In comparison with baseline schemes, simulation results show that the proposed scheme achieves higher gains in aggregate throughput, cell-edge throughput, and outage probability.

F. Kording, J. Yamamura, F. Ueberle, C. Remus, G. Adam und B. Schönnagel
Doppler Ultraschall im Vergleich zu Elektrokardiogramm und Pulsoximetrie bei 3T
Fortschr Röntgenstr 2015,

Marker: LS

Konferenz, Symposium, Vortragsreihe, Einzelausstellung, Modenschau, Künstl. Leitung (als Ausrichter):

Ziyang Wang, Rainer Schoenen, Halim Yanikomeroglu und Marc St.Hilaire
Load balancing in cellular networks with user-in-the-loop: A spatial traffic shaping approach
IEEE International Conference on Communications (ICC)
8–12 June 2015
Proceedings of the IEEE International Conference on Communications (ICC)

Marker: EuI

Meisam Mirahsan, Rainer Schoenen, Sebastian Szyszkowicz und Halim Yanikomeroglu
Spatial heterogeneity of users in wireless cellular networks based on open urban maps
IEEE International Conference on Communications (ICC)
Proceedings of the IEEE International Conference on Communications (ICC)

Marker: EuI

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Letzte Änderung: 23.01.15

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