| 1. |
- Makki, Behrooz, 1980, et al.
(författare)
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Coordinated Multi-point Joint Transmission with Partial Channel Information Feedback
- 2013
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Ingår i: European Wireless Conference. - 9783800734986
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Konferensbidrag (refereegranskat)abstract
- This paper studies the data transmission efficiency of a coordinated multi-point (CoMP) network in the presence of partial channel state information (CSI). The system throughput is obtained in the case where the base stations are provided with a quantized channel phase information. Assuming slow-fading channels, discussions about the optimal quantization boundaries and adaptive power allocation are presented. Moreover, we demonstrate the equivalency of the quantized CSI scheme with a hybrid automatic repeat request protocol, in terms of throughput. Considerable performance improvement is observed with even a single bit feedback per user.
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| 2. |
- Parruca, Donald, et al.
(författare)
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On Semi-Static Interference Coordination under Proportional Fair Scheduling in LTE Systems
- 2013
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Ingår i: Proceedings of the 2013 19th European Wireless Conference (EW). - : VDE Verlag GmbH. - 9783800734986
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Konferensbidrag (refereegranskat)abstract
- In this paper we consider the design of semi-static inter-cell interference coordination schemes for LTE networks. In this approach, base stations coordinate the power settings per resource block over long time spans such as seconds. In order to optimize the power settings, one needs to employ models which predict the rate of terminals over the next coordination period under the usage of a given power setting. However, these models are typically quite simple and neglect the impact from fading as well as from dynamic resource allocation performed at the base stations on a millisecond basis. Ignoring such properties of OFDMA networks leads therefore to suboptimal transmit power settings. In this paper, we study the impact from a precise rate prediction model that accurately accounts for fading and dynamic resource allocation. On the down-side, this more precise model leads to a much more involved optimization problem to be solved once per coordination period. We propose two different heuristic methods to deal with this problem. Especially the usage of genetic algorithm results to be promising to counteract the complexity increase. We then study the overall system performance and find precise rate prediction models to be essential for semi-static interference coordination as they provide significant performance improvements in comparison to approaches with simpler models.
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| 3. |
- Weyres, Marco, et al.
(författare)
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Effective Service Capacity Analysis of Interference-Limited Multi-Carrier Wireless Systems
- 2013
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Ingår i: Proceedings of the 2013 19th European Wireless Conference (EW). - : VDE Verlag GmbH. - 9783800734986 ; , s. 1-7
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Konferensbidrag (refereegranskat)abstract
- A good utilization of a wireless network while still ensuring QoS-constraints for all users is a hard challenge for service providers. Especially for admission control or handover decisions it is important to have a good approximation of the possible rate a user can achieve with respect to QoS parameters like delay or outage probabilities. Since fourth generation cellular networks utilize a frequency reuse of one, especially terminals at the cell edge suffer from inter-cell interference. In order to provide them with rates that guarantee specific QoS parameters without reserving too much resources, a good prediction of their possible rates is needed. Unfortunately, the prediction of the rates in an interference-limited cell is a complex and hard problem. Hence, it is a common way to simplify calculations by treating interference as additional noise in the used system models. In this paper we derive closed-form solutions for the delay distribution of interference-limited cells with respect to an OFDMA and a round robin scheduling approach. These distributions can be used to predict the possible rates of users given their average received transmitter gains, interferer gains and their QoS-constraints in a very accurate way. We validate our derivations and show that a simplification by treating interference as noise leads to an underestimation of rates which lowers the cell throughput. Furthermore, we show that due to the resulting equations, there is no way to derive the rates for interference limited cells in a linear way from easier solutions given by noise-limited cells.
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