Coexistence of FDD flexible duplexing networks

Lembo, Sergio; Tirkkonen, Olav; Goldhamer, Mariana; Kliks, Adrian

doi:10.1109/eucnc.2017.7980723

Cited by 5 publications

(4 citation statements)

References 7 publications

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“…Here, we assume that UL and DL occur at the same time but over different SCs [15]- [17], i.e., the flexible frequency division duplex (FDD) mode [19], [20]. To avoid inter-link interference, each SC can be assigned to either UL or DL of a user.…”

Section: A System Modelmentioning

confidence: 99%

“…In particular, the authors in [18] investigated the dynamic time division duplex (TDD) resource allocation in both homogeneous and heterogeneous networks. Considering the effect of adjacent channel emissions, [19] studied the coexistence of flexible FDD where the UL band can be utilized for DL. In [20], the authors studied flexible FDD with power control and network-based interference cancellation to support dynamic asymmetric DL/UL traffic.…”

Section: Introductionmentioning

confidence: 99%

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Joint Uplink and Downlink Transmissions in User-Centric OFDMA Cloud-RAN

Lin

Liu

2019

IEEE Trans. Veh. Technol.

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This paper studies joint uplink (UL) and downlink (DL) resource allocation in user-centric orthogonal frequency division multiple access (OFDMA) cloud radio access network (CRAN), where the users select the distributed remote radio heads (RRHs) to cooperatively serve their UL and DL transmissions over different subcarriers (SCs). The goal of this paper is to maximize the system throughput through jointly optimizing UL/DL scheduling, SC assignment, RRH grouping/clustering and power allocation under the maximum power and fronthaul capacity constraints. The problem is formulated as a mixed integer programming problem which is non-convex and NP-hard. We propose an efficient algorithm based on the Lagrange duality method to obtain an asymptotically optimal solution for this problem. A heuristic algorithm is further proposed to reduce the complexity. Simulation results illustrate that the proposed heuristic algorithm also has a close-to-optimal performance, and the proposed algorithms can considerably improve the system throughput compared to other benchmark schemes.Index Terms-Cloud radio access network (CRAN), resource allocation, orthogonal frequency division multiple access (OFDMA).

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Section: A System Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Joint Uplink and Downlink Transmissions in User-Centric OFDMA Cloud-RAN

Lin

Liu

2019

IEEE Trans. Veh. Technol.

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“…Regarding power efficiency, most of the works are still focused on orthogonal TDD access techniques [14][15][16][17]. However, a power optimization method with flexible UL/DL sets is provided in [18], and afterwards, authors in [19] analyze the coexistence of UL and DL cells in terms of downlink transmit power. A remarkable study is performed in [20], where a variation of flexible duplexing called α-duplex is introduced.…”

Section: Introductionmentioning

confidence: 99%

Power Minimization in Multi-tier Networks with Flexible Duplexing

Fanjul

Santamarı́a

2019

ICASSP 2019 - 2019 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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In this paper we present an algorithm to minimize transmit power in multiple-input multiple-output (MIMO) heterogeneous networks (HetNets) with flexible duplexing, a promising strategy that allows the coexistence of uplink and downlink cells within the same time and frequency resource block. First, the proposed algorithm minimizes transmit power for a given uplink/downlink (UL/DL) combination, and afterwards, the optimal solution out of the explored UL/DL combinations is selected. To reduce the computational cost of exploring all the UL/DL settings, we propose a hierarchical switching (HS) approach that considers a reduced subset of transmit directions. By means of Monte Carlo simulations, we show that the proposed technique provides significant power savings with respect to a conventional time-division duplex (TDD) scheme.

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“…A more general analysis is performed in [5] building on the so-called α-duplex model. Additionally, the coexistence of FDD flexible duplexing systems is studied in [6] in terms of downlink transmit power, and frame structures for interference mitigation in flexible duplexing transmissions can be found in [7], [8], [9].…”

Section: Introductionmentioning

confidence: 99%

Flexible Duplexing for Maximum Downlink Rate in Multi-Tier MIMO Networks

Fanjul

Santamarı́a

2018

2018 26th Telecommunications Forum (TELFOR)

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In this paper, we propose an algorithm to maximize downlink rate performance in the context of multiple-input multiple-output (MIMO) Heterogeneous Networks (HetNets). Specifically, we evaluate the benefits of flexible duplexing, a promising strategy that consists in combining uplink and downlink cells within the same channel use. In order to handle intercell interference, we rely on the interference alignment (IA) technique, taking into account the impact of the channel estimation errors on the inter-cell interference leakage. Determining the best uplink/downlink configuration is a combinatorial problem, and therefore we consider several approaches to reduce the computational demands of the problem. First, we use a statistical characterization for the average rates achieved by IA in order to avoid the calculation of alignment solutions for all possible settings in the network. Additionally, we propose two hierarchical switching (HS) strategies so that only a subset among the total number of combinations is explored. As a performance baseline, we include in the comparison the conventional time division duplex (TDD) approach and the well-known minimum mean square error (MMSE) decoder. The obtained results show that downlink rates achieved by implementing flexible duplexing and applying inter-cell IA significantly outperform conventional TDD transmissions. Finally, the proposed hierarchical schemes are shown to obtain almost the same rates as exhaustive search with much lower computational cost.

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Coexistence of FDD flexible duplexing networks

Cited by 5 publications

References 7 publications

Joint Uplink and Downlink Transmissions in User-Centric OFDMA Cloud-RAN

Joint Uplink and Downlink Transmissions in User-Centric OFDMA Cloud-RAN

Power Minimization in Multi-tier Networks with Flexible Duplexing

Flexible Duplexing for Maximum Downlink Rate in Multi-Tier MIMO Networks

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