| 1. |
- Oechtering, Tobias J., et al.
(författare)
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A new cooperative transmission scheme using the space-time delay code
- 2004
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Ingår i: 2004 ITG. - : VDE Verlag GmbH. ; , s. 41-48
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Konferensbidrag (refereegranskat)abstract
- We propose a new resource efficient transmission scheme to achieve cooperative diversity of a distributed smart antenna system consisting of an information source, destination, and two alternating supportive relay stations. Each station is equipped with one antenna element. Furthermore we assume perfect synchronization and channel knowledge at the receivers. The proposed linear encoding functions with interference cancellation at one relay station result in an equivalent space-time delay coded system, but with additionally colored noise from the relay stations. Based on the maximum likelihood sequence estimator we derive criteria to evaluate the performance compared to the direct SISO transmission. Finally the numerical simulation results of an suboptimal sequence estimator show significant performance gains if the power gain from the hopping is gainful exploited. If not, the additional noise from the relay stations will degrade the performance at reasonable transmit powers.
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| 2. |
- Oechtering, Tobias J., et al.
(författare)
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On the capacity of a distributed multiantenna system using cooperative transmitters
- 2003
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Ingår i: 57TH IEEE VEHICULAR TECHNOLOGY CONFERENCE, VTC 2003-SPRING, VOLS 1-4, PROCEEDINGS. - 0780377575 ; , s. 75-79
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Konferensbidrag (refereegranskat)abstract
- Future radio systems will make use of cooperative concepts between independent transmitters and receivers to increase the coverage area and the data rate, and/or to decrease the power consumption of the wireless communication network. Therefore, a station wishing to transmit cooperates with reachable stations in its vicinity to achieve a performance gain from the resulting distributed multiple antenna link. The resulting communication situation is related to the common multiple access channel. We consider the simple cooperative concept of amplify and forward, where the cooperating stations retransmit the amplified, received signal. In order to gain knowledge about the properties of the cooperative transmitter system, it is sensible to analyze its capacity. Furthermore, the amplification factors which maximize the system capacity with respect to the total transmission power of all transmit stations will lead to important system design information.
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| 3. |
- Oechtering, Tobias J., et al.
(författare)
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Optimality range of transmission over different terminals in cooperative multiantenna systems
- 2003
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Ingår i: 2003 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH, AND SIGNAL PROCESSING, VOL IV, PROCEEDINGS. - 0780376633 ; , s. 365-368
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Konferensbidrag (refereegranskat)abstract
- In our work we study a cooperative system using multiplexing. The key idea of a cooperative system is, that spatially separated stations assist each other to build up a distributed smart antenna and thereby to improve the efficiency of their transmissions. Here, the multiple antenna link will be exploited by multiplexing. In order to evaluate the multiple antenna link, we introduce a system model considering one cooperative station. From this, we present the capacity and some properties of system which differ form ordinary MIMO systems. Furthermore we derive the optimal amplification factors, which specify the optimal power allocation. Finally we compare the ergodic capacity between simple and cooperative transmission.
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| 4. |
- Sezgin, A, et al.
(författare)
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A new resource efficient transmission scheme for Cooperative Systems
- 2004
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Ingår i: 2004 IEEE 5TH WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS. ; , s. 298-302
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Konferensbidrag (refereegranskat)abstract
- Multiple transmit antennas will play an essential part in order to support a high link quality in wireless communications systems. In this work, we employ multiple antennas at the mobile station to perform cooperative space-time coding with other spatially distributed relay stations in a wireless network in order to achieve spatial diversity. Furthermore, through cooperation of the mobile station with relay stations it is possible to cope with distortions due to impairments like, e.g., path-loss and shadowing. Therefore, we propose a regular block Markov superposition encoding strategy based on space-time block codes (STBC) for a cooperative system with one mobile transmitting station and two relay stations, either mobile themselves or fixed. These relay stations cooperate by detecting and retransmitting the information received from the transmitter to the destination. Applying our proposed strategy achieves the same diversity gain of a multiple-input-multiple-output (MIMO) single user system with the same number of transmit and receive antennas. Simulation results show significant improvements in comparison to the system without cooperation.
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| 5. |
- Sezgin, A., et al.
(författare)
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Antenna selection with capacity-approaching space-time block codes
- 2004
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Ingår i: CONFERENCE RECORD OF THE THIRTY-EIGHTH ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS & COMPUTERS, VOLS 1 AND 2. - 0780386221 ; , s. 1291-1294
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Konferensbidrag (refereegranskat)abstract
- Recently, a quasi-orthogonal space-time block code (QSTBC) capable of approaching the maximum outage mutual information of a MIMO system for the case of four transmit and one receive antennas was proposed. Based on the generalization of these QSTBC to 2(n) transmit antennas and arbitrary number of receive antennas, we analyze the impact of antenna selection (AS) by choosing one out of n(R) receive antennas based on different selection criteria on both the outage probability and the bit error rate. Furthermore, we derive a lower bound for the fraction of outage probability achieved with QSTBC combined with AS. Simulation results show, that even the ZF-detector with AS outperforms the ML-detector without AS by using only one extra antenna, thereby dramatically reducing the computational complexity of the receiver.
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| 6. |
- Sezgin, A., et al.
(författare)
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On the outage probability of quasi-orthogonal space-time codes
- 2004
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Ingår i: 2004 IEEE INFORMATION THEORY WORKSHOP, PROCEEDINGS. ; , s. 381-386
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Konferensbidrag (refereegranskat)abstract
- Recently, a quasi-orthogonal space-time block code (QSTBC) capable of achieving a significant fraction of the outage mutual information of a multiple-input-multiple output (MIMO) wireless communication system for the case of four transmit and one receive antennas was proposed. We generalize these results to 2(n) transmit and an arbitrary number of receive antennas. Furthermore, we derive an analytical lower bound for the fraction of outage probability achieved with QSTBC and show that this bound is tight for low signal-to-noise-ratios (SNR) values and also for increasing number of receive antennas. We present also an upper bound, which is tight for high SNR values and derive analytical expressions for the case of four transmit antennas. Furthermore, by utilizing the special structure of the QSTBC we propose a new transmit strategy, which decouples the signals transmitted from different antennas in order to detect the symbols separately with a linear ML-detector rather than joint detection, an up to now only known advantage of orthogonal space-time codes (OSTBC).
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| 7. |
- Walke, C M, et al.
(författare)
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Analytical expression for uplink C/I-distribution in interference-limited cellular radio systems
- 2002
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 38:14, s. 743-744
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Tidskriftsartikel (refereegranskat)abstract
- The cumulative distribution function (CDF) of the uplink carrier-to-interference ratio (C/I) of an interference-limited cellular radio network is presented. Based on this and on the assumptions of Gaussian inter-cell interference and flat Rayleigh fading channels, the CDF of the bit error ratio for a QPSK-modulated space/time/code division multiple access system deploying a zero-forcing block linear equaliser with receive antenna diversity is derived.
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