A decentralized cooperative Uplink/Downlink adaptation scheme for TDD Small Cell Networks

Dowhuszko, Alexis A.; Tirkkonen, Olav; Karjalainen, Juha; Henttonen, Tero; Pirskanen, Juho

doi:10.1109/pimrc.2013.6666413

Cited by 34 publications

(28 citation statements)

References 16 publications

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“…One may find works on dynamic TDD that mainly focus on optimizing the UL-DL configuration ( [2], [6], [7]) or the DL-to-UL switching point decision ( [8]- [10]) within an LTE frame. The optimization is done either per SC or per group of SCs and, in many cases, it is constrained to the 7 LTE frame patterns predefined in LTE TDD [5].…”

Section: Introductionmentioning

confidence: 99%

“…This way, DLto-UL and UL-to-DL intra-cluster interference is avoided but the flexibility of adapting to the per-SC traffic asymmetries is reduced. On the other hand, decentralized solutions are investigated in [6], [8]- [10]. In [8], the decision on the DL-to-UL switching point is performed at each SC in coordination with neighboring SCs thanks to the exchange of backhaul control plane messages (prices) that take into account the traffic asymmetry of the serving users and how such decision affects to users associated to neighboring SCs.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, decentralized solutions are investigated in [6], [8]- [10]. In [8], the decision on the DL-to-UL switching point is performed at each SC in coordination with neighboring SCs thanks to the exchange of backhaul control plane messages (prices) that take into account the traffic asymmetry of the serving users and how such decision affects to users associated to neighboring SCs. In [9], the problem is formulated as a non-cooperative game so as to minimize the overall UL and DL delay at each SC.…”

Section: Introductionmentioning

confidence: 99%

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Joint User Scheduling, Precoder Design, and Transmit Direction Selection in MIMO TDD Small Cell Networks

Lagén

Agustín

Vidal

2017

IEEE Trans. Wireless Commun.

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This is the author's version of an article that has been accepted for publication in IEEE Trans. on Wireless Commun.Changes were made to this version by the publisher prior to publication.Abstract-New short-length single-direction frame structures are proposed for 5G time division duplex (TDD) systems, where the transmit direction (i.e. either downlink (DL) or uplink (UL)) can be independently chosen at each cell in every frame. Accordingly, high flexibility is provided to match the per-cell DL/UL traffic asymmetries and full exploitation of dynamic TDD is allowed. As a downside, interference management becomes crucial. In this regard, this paper proposes a procedure for dynamic TDD in dense MIMO small cell networks, where the transmit direction selected per small cell (SC) is dynamically optimized together with the user scheduling and transmit precoding. We focus on the maximization of a general utility function that takes into account the DL/UL traffic asymmetries of each user and the interference conditions in the network. Although the problem is non-convex, it is decomposed thanks to the interferencecost concept and then efficiently solved in parallel. Simulation results show gains in DL and UL average rates for different traffic asymmetries and SC/user densities as compared to existing dynamic TDD schemes thanks to the proposed joint optimization. The gains become more significant when there is high interference and limited number of antennas.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Joint User Scheduling, Precoder Design, and Transmit Direction Selection in MIMO TDD Small Cell Networks

Lagén

Agustín

Vidal

2017

IEEE Trans. Wireless Commun.

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“…Most dynamic TDD analysis studies system interference conditions with different UL/DL configurations and assumes that the UL/DL configuration is changed instantaneously [3][4][5]. Moreover, interference is usually modeled by an ON/OFF model.…”

Section: Introductionmentioning

confidence: 99%

Dynamic TDD in LTE small cells

Kerttula

Marttinen

Ruttik

et al. 2016

J Wireless Com Network

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Dynamic time-division duplexing (TDD) enables adjustments of uplink (UL) and downlink (DL) resources flexibly according to the instantaneous traffic load. Long-Term Evolution (LTE) systems can be implemented in TDD mode (TD-LTE). However, the dynamic change of a TDD configuration has not been well supported and investigated. In large macro cells, the high transmit power of base stations (BSs) easily blocks the weaker user equipment's (UE) UL signal (called the UL-DL interference); and therefore, neighboring cells usually operate with the same TDD configuration. In small cells, such as femtocells, the BS and UE transmission powers are in the same order and the system can afford to have overlapping UL-DL subframes. In addition, when DL load is light, the BS transmits empty DL subframes with only a reference signal (RS). In this paper, we measured the interference caused by DL RS. This interference is not negligible; and therefore, it is beneficial to reduce the amount of DL subframes by switching lightly loaded BSs to UL-heavy subframe configuration. We illustrate with simulations that this can improve system efficiency. Changing the subframe configuration dynamically has a switching-related cost. Frequent switching between subframe configurations can actually decrease throughput. We describe conditions where configuration change is beneficial. We also propose an algorithm that decreases the switching overhead and improves the ability to adapt to varying loads.

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“…이러한 이종 네트워크에서, 만약 매크로 셀과 소형 셀이 서로 다른 트래픽 비율로 운용된다면 같은 트래 픽 비율로 운용되는 경우 대비 주파수 자원 재사용 효 율을 높임과 동시에 셀 수율 (Cell Throughput)을 추 가적으로 향상시킬 수 있다 [4][5][6] . 따라서 이종 네트워크 에서 매크로 셀과 소형 셀이 서로 다른 트래픽으로 운 용되는 시스템에 대한 연구가 활발히 진행되고 있다 [5][6][7][8] . [9,10] .…”

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Study on Power Allocation for Heterogeneous Networks Based on Asynchronous TDD

Min¹,

Kim²,

Park³

et al. 2014

The Journal of Korean Institute of Communications and Informati

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This paper analyzes the power allocation scheme to maximize the sum-rate for heterogeneous networks based on asynchronous time division duplex. We consider heterogeneous networks where a small cell exists in the macro cell coverage and the small cell and the macro cell share the same time-frequency resources. We formulate the optimization problem which maximizes the sum-rate of the heterogeneous network subject to the target signal-to-interference-plus-noise ratio. We analyze the feasible region in order for the optimal solution to exists and the optimal power allocation scheme for maximizing the sum-rate. Simulation results show that the proposed power allocation schemes outperform the maximum power transmission scheme.※ 본 연구는 서울특별시의 서울 벨 연구소 사업(서울시 산학연 협력사업(WR080951)) 및 2014년 교육인적자원부 BK21 플러스 사업 의 일환인 연세대학교 BEST 정보기술 사업단의 지원을 받아 수행되었음.

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A decentralized cooperative Uplink/Downlink adaptation scheme for TDD Small Cell Networks

Cited by 34 publications

References 16 publications

Joint User Scheduling, Precoder Design, and Transmit Direction Selection in MIMO TDD Small Cell Networks

Joint User Scheduling, Precoder Design, and Transmit Direction Selection in MIMO TDD Small Cell Networks

Dynamic TDD in LTE small cells

Study on Power Allocation for Heterogeneous Networks Based on Asynchronous TDD

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