| 21. |
- Seifi, Nima, 1981, et al.
(författare)
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Coordinated Single-Cell vs Multi-Cell Transmission with Limited-Capacity Backhaul
- 2010
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Ingår i: IEEE Asilomar Conf. on Signals, Systems, and Computers, Pacific Grove, CA, Nov. 2010. - 1058-6393. - 9781424497218 ; , s. 1217-1221
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Konferensbidrag (refereegranskat)abstract
- Base station coordination is an efficient techniqueto transcend the limits on spectral efficiency imposed by intercellinterference. In this paper, we compare the performance ofdifferent coordination strategies with different amount of channelstate information (CSI) and data sharing among the coordinatingbase stations. We focus on the effect of limited backhaul capacityin a two-cell network. Contrary to the common belief, we showthat coordination strategies with no data and only limited CSIsharing is preferred to those with full data and CSI sharing whenthe backhaul capacity is relatively low and the edge SNR is high.
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| 22. |
- Seifi, Nima, 1981, et al.
(författare)
-
Coordinated user scheduling in the multi-cell MIMO downlink
- 2011
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. - 9781457705373 ; , s. 2840 - 2843
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Konferensbidrag (refereegranskat)abstract
- We propose a novel, coordinated user scheduling (CUS) algorithm for inter-cell interference (ICI) mitigation in the downlink of a multi-cell multi-user MIMO system. In the proposed algorithm, ICI mitigation is performed through the exchange of necessary channel state information (CSI) among the base stations, and the revision of the scheduling decisions and beamformer designs at each base station. Furthermore, ICI mitigation is performed only for the cell-edge users so that the amount of inter-base station signaling overhead is minimized. Our simulation results demonstrate that the proposed coordination scheduling algorithm significantly improves the cell-edge users' throughput compared to conventional systems with only a negligible amount of CSI sharing among the base stations and a relatively small throughput loss for the cell-interior users.
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| 23. |
- Seifi, Nima, 1981, et al.
(författare)
-
Multimode Transmission in Network MIMO Downlink with Incomplete CSI
- 2011
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Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180. ; 2011, s. Art. no. 743916-
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Tidskriftsartikel (refereegranskat)abstract
- We consider a cooperative multi-cell MIMO (a.k.a network MIMO) downlink system with multiantennabase stations (BSs), which are connected to a central unit and communicate with multi-antennausers. In such a network, obtaining perfect channel state information (CSI) of all users at the central unitto exploit opportunistic scheduling requires a substantial amount of feedback and backhaul signaling.In this paper, we propose a scheduling algorithm based only on the knowledge of the average receivedSNR at each user from all the cooperating BSs, denoted as incomplete CSI. Multi-mode transmission isapplied that is able to adaptively adjust the number of data streams transmitted to each user. Utilizingthe results of random matrix theory, an analytical framework is proposed to approximate the ergodicrate of each user with different number of data streams. Using these approximate ergodic rates, a jointuser and mode selection algorithm is proposed, where only the scheduled users need to feed backinstantaneous CSI. Simulation results demonstrate that the developed analytical framework providesa good approximation for a practical number of antennas. While substantially reducing the feedbackoverhead, it is shown that the proposed scheduling algorithm performs closely to the opportunisticscheduling algorithm that requires instantaneous CSI feedback from all users.
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| 24. |
- Ström, Marie, 1984, et al.
(författare)
-
Low PAPR waveform synthesis with application to wideband MIMO radar
- 2011
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Ingår i: Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP), 2011 4th IEEE International Workshop on. - 9781457721052 ; , s. 5-8
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Konferensbidrag (refereegranskat)abstract
- This paper considers the problem of waveform synthesis given a desired power spectrum. The properties of the designed waveforms are such that the overall system performance is increased. The metric used to evaluate the optimality of the synthesized time domain signals is the peak-to-average power ratio (PAPR). We discuss how to synthesize waveforms using the technique of partial transmit sequence (PTS). The key point is that the gradient can explicitly be derived from the objective function. Furthermore, the result is extended by allowing the power spectrum to deviate from its original shape, yielding a further reduction in the PAPR. The method is applied to derived power spectra for wideband multiple-input-multiple-output (MIMO) radar. It is shown that the proposed technique can achieve optimal or near optimal performance with PAPR below 0.5 dB.
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| 25. |
- Ström, Marie, 1984, et al.
(författare)
-
Transmit and receive filter optimization for wideband MIMO radar
- 2011
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Ingår i: Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP), 2011 4th IEEE International Workshop on. - 9781457721052 ; , s. 9-12
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we discuss the possibility to suppress interference for wideband multiple-input-multiple-output (MIMO) radar, using only the temporal properties of the signals. The idea is to use tunable filters each connected to a wideband waveform generator, and to derive the optimal power spectral density (PSD) of the resulting signals in a known environment. The metric used to evaluate the enhancement in the system performance is the signal-to-noise and interference ratio (SNIR), from which the optimal transmit and receive filter properties are derived. We discuss two optimization approaches: one alternating and one joint algorithm. Each method is separated into two cases: for a total power constraint and for an individual power constraint on the transmit filters, respectively. Numerical validation illustrates the possibility to suppress the interference in the temporal domain, without actually forming a spatial null in the direction of the interference.
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