| 1. |
- Blad, Anton, et al.
(författare)
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Spectrum Sensing of OFDM Signals in the Presence of CFO : New Algorithms and Empirical Evaluation Using USRP
- 2012
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Ingår i: Proceedings of the 13th IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC). - : IEEE. - 9781467309691 - 9781467309707 - 9781467309714 ; , s. 159-163
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Konferensbidrag (refereegranskat)abstract
- In this work, we consider spectrum sensing of OFDM signals. We deal withthe inevitable problem of a carrier frequency offset, and propose modificationsto some state-of-the-art detectors to cope with that. Moreover, the (modified)detectors are implemented using GNU radio and USRP, and evaluated over aphysical radio channel. Measurements show that all of the evaluated detectorsperform quite well, and the preferred choice of detector depends on thedetection requirements and the radio environment.
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| 2. |
- Katselis, Dimitrios, et al.
(författare)
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A Chernoff convexification for chance constrained MIMO training sequence design
- 2012
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Ingår i: Signal Processing Advances in Wireless Communications (SPAWC), 2012 IEEE 13th International Workshop on. - : IEEE. - 9781467309714 ; , s. 40-44
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Konferensbidrag (refereegranskat)abstract
- In this paper, multiple input multiple output (MIMO) channel estimation formulated as a chance constrained problem is investigated. The chance constraint is based on the presumption that the estimated channel can be used in an application to achieve a given performance level with a prescribed probability. The aforementioned performance level is dictated by the particular application of interest. The resulting optimization problem is known to be nonconvex in most cases. To this end, convexification is attempted by employing a Chernoff inequality. As an application, we focus on the estimation of MIMO wireless channels based on a general L-optimality type of performance measure.
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| 3. |
- Li, Jingya, 1986, et al.
(författare)
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Resource allocation for OFDMA systems with multi-cell joint transmission
- 2012
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Ingår i: 2012 IEEE 13th International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2012. Cesme, 17-20 June 2012. - 9781467309714 ; , s. 179-183
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Konferensbidrag (refereegranskat)abstract
- This paper considers the downlink resource allocation of a coordinated multi-cell cluster in OFDMA systems with universal frequency reuse. Multi-cell joint transmission is considered via zero-forcing precoding. Furthermore, joint optimization of the user selection and power allocation across multiple subchannels and multiple cells is studied. The objective is to maximize the weighted sum rate under per-base-station power constraints. Based on general duality theory, two iterative resource allocation algorithms are proposed and compared with the optimal solution, which requires an exhaustive search of all possible combinations of users over all subchannels. Simulation results show that the two proposed algorithms achieve a performance very close to the optimal, with much lower computational complexity. In addition, we show that joint user set selection across multiple subchannels significantly improves the system performance in terms of the weighted sum rate.
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| 4. |
- Lindblom, Johannes, 1983-, et al.
(författare)
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Does non-orthogonal spectrum sharing in the same cell improve the sum-rate of wireless operators?
- 2012
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Ingår i: Proceedings of the 13th IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC). - 9781467309707 - 9781467309691 - 9781467309714 ; , s. 6-10
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Konferensbidrag (refereegranskat)abstract
- We study non-orthogonal spectrum sharing to determine under what circumstances operators can gain by such sharing. To model the spectrum sharing, we use the multiple-input single-output (MISO) interference channel (IC) assuming that the operators transmit in the same band. For the baseline scenario of no sharing, we use the MISO broadcast channel (BC) assuming that the operators transmit in disjunct bands. For both the IC and BC, we give achievable (lower) and upper bounds on the maximum sum-rate. While these bounds are well-known we also propose a new fast algorithm for finding a lower bound on the sum-rate of the BC using linear beamforming.We use the bounds to numerically evaluate the potential gain of non-orthogonal spectrum sharing. In this study we assume that the operators efficiently utilize all their spatial degrees of freedom. We will see that the gains from spectrum sharing under these circumstances are limited.
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| 5. |
- Makki, Behrooz, 1980, et al.
(författare)
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Interference-free spectrum sharing using a sequential decoder at the primary user
- 2012
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Ingår i: 2012 IEEE 13th International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2012. Cesme, 17 June - 20 June 2012. - 9781467309714 ; , s. 154-158
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Konferensbidrag (refereegranskat)abstract
- Recently, substantial attention has been paid to improve the spectral efficiency of communication setups using different spectrum sharing techniques. This paper studies the ergodic achievable rate of spectrum sharing channels in the case where the primary licensed user is equipped with a sequential decoder, while there is no connection between the transmitters. Assuming Rayleigh block-fading channels, the unlicensed user ergodic achievable rate is obtained under an extremely hard constraint where no interference is tolerated by the licensed user receiver. Simulation results show that using sequential decoders there is considerable potential for data transmission of the unlicensed user with no performance degradation of the licensed user. Moreover, in contrast to previously proposed schemes, the network sum rate increases by implementation of sequential decoders.
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