| 1. |
- Aydin, Osman, et al.
(författare)
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EU FP7 INFSO-ICT-317669 METIS, D 4.1 Summary on preliminary trade-off investigations and first set of potential network-level solutions
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- METIS WP4 covers research activities in network-level aspects of the advancement of wireless network technologies towards the year 2020 and beyond. The aim is to develop novel network-level technology concepts to address the challenges foreseen in future scenarios with regard to interference, traffic and mobility management issues. Moreover, another task of this work package is to propose functional enablers which can support the above potential solutions.This document provides* a report of the ongoing progress in WP4 regarding the research topics agreed upon in IR 4.1,* a high level description of the proposed concepts and approaches adopted by different partners.More specifically, the document describes, first set of potential network-level solutions and presents some first research results in order to position them with regards to the state of the art approaches. It also gives an overview of research activities to be considered later in WP4.
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| 2. |
- Carvalho, E. de, et al.
(författare)
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EU FP7 INFSO-ICT-317669 METIS, D3.1 Positioning of multi-node/multi-antenna technologies
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This document describes the research activity in multi-node/multi-antenna technologies within METIS and positions it with respect to the state-of-the-art in the academic literature and in the standardization bodies. Based on the state-of-the-art and as well as on the METIS objectives,we set the research objectives and we group the different activities (or technology components) into research clusters with similar research objectives. The technologycomponents and the research objectives have been set to achieve an ambidextrous purpose. On one side we aim at providing the METIS system with those technological components that are a natural but non-trivial evolution of 4G. On the other side, we aim at seeking for disruptivetechnologies that could radically change 5G with respect to 4G. Moreover, we mapped the different technology components to METIS’ other activities and to the overall goals of theproject.
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| 3. |
- Lakshmana, Tilak Rajesh, 1980
(författare)
-
Efficient Backhauling in Cooperative MultiPoint Cellular Networks
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The efficient use of the spectrum in cellular systems has given rise to cell-edge user equipments (UEs) being prone to intercell interference. In this regard, coordinated multipoint (CoMP) transmission is a promising technique that aims to improve the UE data rates. In a centralized network architecture, the users need to feed back the channel state information (CSI) to its anchor base station (BS). The CSI is then forwarded to a central coordination node (CCN) for precoder design to jointly mitigate interference. However, feeding back the CSI consumes over-the-air uplink resources as well as backhaul resources. To alleviate this burden, the quantity of CSI being fed back is limited via relative thresholding. That is, the CSI feedback is limited to those BSs whose signal strength fall above a threshold relative to the strongest BS. Moreover, with limited CSI, efficient backhauling of the precoding weights is necessary, as the user data is routed based on the path taken by the precoding weights from the CCN to the corresponding BSs. The focus of this thesis is mainly on a physical (PHY) layer and a medium access control (MAC) layer approach for reducing the backhaul load in a CoMP system, with minimal penalty on the potential CoMP gains. Furthermore, broadcasting the CSI in a decentralized network architecture is considered in order to reduce backhaul latency.In the PHY layer approach, the precoder design is based on stochastic optimization such as particle swarm optimization (PSO). This method has no constraints on the scheduling of the UEs. The PSO based precoder design was also applied to field measurement data with CSI imperfections due to prediction errors and quantization errors. It was found to perform the best compared to other robust precoders de- veloped in the EU FP7 ARTIST4G consortium. With the MAC layer approach, a simple zero forcing precoder is assumed, which focuses on how to schedule the UEs in such a way that they achieve the backhaul load reduction. Lastly, the decentralized network architecture is explored, where the UEs broadcast the CSI. The BSs coordinate by sharing minimal scheduling information, thereby achieving data rates comparable to the centralized network architecture.In this thesis, the backhauling is defined to be efficient when the total number of CSI coefficients aggregated at the CCN is equal to the total number of precoding weights for a given time-frequency resource, in a centralized architecture with the PHY layer approach. In the MAC layer approach, the total number of precoding weights is less than or equal to the total number of CSI coefficients. In the decentralized network architecture, the CCN does not exist. The BSs can coordinate over a less stringent backhaul, thereby reducing the backhaul load and latency.
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| 4. |
- Lakshmana, Tilak Rajesh, 1980, et al.
(författare)
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Scheduling for Backhaul Load Reduction in CoMP
- 2013
-
Ingår i: IEEE Wireless Communications and Networking Conference, WCNC. - 1525-3511. - 9781467359399 ; , s. 227-232
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Konferensbidrag (refereegranskat)abstract
- Coordinated multi-point (CoMP) transmission has received a lot of attention, as a way to improve the system throughput in an interference limited cellular system. For joint processing in CoMP, the user equipments (UEs) need to feed back the channel state information (CSI), typically to their serving base stations (BSs). The BS forwards the CSI to a central coordination node (CCN) for precoding. These precoding weights need to be forwarded from the CCN to the corresponding BSs to serve the UEs. In this work, a feedback load reduction technique is employed via partial joint processing to alleviate the CSI feedback overhead. Similarly, to achieve backhaul load reduction due to the precoding weights, scheduling approaches are proposed. The state of the art block diagonalization solution is compared with our proposed constrained and unconstrained scheduling. Our main contribution is the method of choosing the best subset of the BSs and UEs at the CCN that yields the best sum rate under the constraint of efficient backhaul use. In particular, with constrained scheduling, the choice of a smaller subset proportionally reduces the backhaul load. Simulation results based on a frequency selective WINNER II channel model, show that our proposed constrained scheduling outperforms the block diagonalization approach in terms of the average sum rate per backhaul use.
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