| 1. |
- Karipidis, Eleftherios, 1978-, et al.
(författare)
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Transmit Beamforming for Inter-Operator Spectrum Sharing
- 2011
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Ingår i: Proceedings of the Future Network and Mobile Summit Conference.
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Konferensbidrag (refereegranskat)abstract
- We study the nonorthogonal spectrum sharing scenario, in which coexisting transmitters of different operators concurrently utilize the same frequency band. The transmitters (and possibly the receivers) are equipped with multiple antennas. In EU FP7 project SAPHYRE, we propose various transmit beamforming techniques to manage the interference in the physical layer. We show that operating points that are more efficient than orthogonal spectrum sharing can be reached, when the operators cooperatively design their beamforming vectors to minimize the interference.
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| 2. |
- Li, J., et al.
(författare)
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Binary field network coding design for multiple-source multiple-relay networks
- 2011
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Ingår i: IEEE Int Conf Commun. - : IEEE. - 9781612842332
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Konferensbidrag (refereegranskat)abstract
- We study the design of network codes for M-source, N-relay wireless networks over slow fading channels. Specifically, vector-wise binary field network coding (BFNC) schemes are proposed. In the construction of our BFNC schemes, we utilize a diversity achieving criterion which can be expressed in terms of the linear independence of quasi-cyclic matrices. Our codes can be implemented with low-complexity encoders at the relays as only binary operations are used. Meanwhile at the destination, for small code lengths, ML decoder can be applied. For large code lengths, we propose a modified BP decoder with low decoding complexity. From analysis and simulations, we show that our proposed BFNC schemes can achieve full diversity for the ML decoder, as well as full diversity for the modified BP decoder we propose for large block lengths. Our simulations also show that our proposed BFNC schemes achieve a higher coding gain relative to previous network coding schemes.
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| 3. |
- Li, J., et al.
(författare)
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One-bit soft forwarding for network coded uplink channels with multiple sources
- 2014
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Ingår i: 2014 IEEE International Conference on Communications, ICC 2014. - : IEEE Computer Society. - 9781479920037 ; , s. 5790-5795
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a threshold-based one-bit soft forwarding (TOB-SF) protocol for a multi-source relaying uplink system with network coding. In the TOB-SF protocol, the relay calculates the log-likelihood ratio (LLR) value of each network coded symbol, compares this LLR value with a pre-optimized threshold, and determines whether to transmit or keep silent. We first derive the bit error rate (BER) expression at the destination, based on which, we optimize the threshold to minimize the BER. Then we theoretically prove that the system can achieve the full diversity gain by using this threshold. Further, we optimize the power allocation at the relay to achieve a higher coding gain. Simulation results show that the proposed TOB-SF protocol outperforms other conventional relaying protocols in terms of error performance.
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| 4. |
- Li, Nan, et al.
(författare)
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Cooperation-based Network Coding in Cognitive Radio Networks
- 2014
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Ingår i: 2014 IEEE 80th Vehicular Technology Conference (VTC Fall). - : IEEE. - 9781479944491 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- We consider a scenario consisting of a primary and asecondary system, each represented by a pair of a transmitter anda receiver. The secondary transmitter assists in the retransmission of the primary message, which prevents the primary performance from being degraded by allowing the secondary system to access the transmission resources. Two network coding schemes applied in retransmission phase are investigated, the stationary network coding (SNC) scheme and the adaptive network coding(ANC) scheme. For each scheme we derive analytical results on packet throughput and infer that the ANC scheme outperforms the SNC scheme. We then provide a numerical performance comparison and a numerical optimization of the secondary packet throughput. Our main result shows cooperation can provide a significant performance improvement through effective network coding.
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| 5. |
- Lu, Lu, et al.
(författare)
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Efficient network coding for wireless broadcasting
- 2010
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Ingår i: IEEE Wireless Communications and Networking Conference, WCNC. - 9781424463961
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Konferensbidrag (refereegranskat)abstract
- It has been shown in the literature that network coding can improve the transmission efficiency of wireless broadcasting as compared to traditional ARQ schemes. In this paper, we propose an improved network coding scheme that can asymptotically achieve the theoretical lower bound on transmission overhead for a sufficiently large number of information blocks. The proposed scheme makes use of an index allocation algorithm that distributes information blocks that have been erased during transmission into a minimum number of encoding sets , where each set represents the erased blocks to be jointly network encoded and retransmitted. Numerical results show that the proposed scheme enables higher transmission efficiencies than traditional ARQ, and previously proposed networks coding schemes for wireless broadcasting.
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| 6. |
- Lu, Lu, et al.
(författare)
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Efficient wireless broadcasting based on systematic binary deterministic rateless codes
- 2010
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Ingår i: IEEE International Conference on Communications.
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Konferensbidrag (refereegranskat)abstract
- We investigate the design and use of systematic binary deterministic rateless (BDR) codes for information transmission over block-erasure broadcast channels. BDR codes are designed to obtain a level of maximal distance separable (MDS) properties, making these codes ideal for the considered broadcast scenario. For a certain number of encoded redundancy blocks, we derive an expression for the probability that the MDS properties are maintained. Moreover, if limited feedback is available, we extend the BDR coding protocol to further improve the system performance. Numerical results show that for a finite number of source blocks and as the number of users grows the proposed systematic BDR codes performs significantly better than LT codes. The proposed schemes with feedback have better performance than traditional ARQ schemes.
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| 7. |
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| 8. |
- Zhao, B., et al.
(författare)
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A NHPP-based reliability model of wireless sensor networks
- 2014
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Ingår i: Applied Mechanics and Materials. - 9783038351764 ; , s. 877-882
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Konferensbidrag (refereegranskat)abstract
- As the Wireless Sensor Networks(WSNs) are widely applied to various fields recent years, the quality of WSN has been increasingly concerned. Since reliability is the most important factor of quality, how to evaluate reliability of WSN through failure counting is our main subject. In this paper, we try to utilize NHPP theorem in the failure process of WSN and propose a reliability model based on NHPP. And also, the model validation is conducted by simulation.
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| 9. |
- Zhao, B., et al.
(författare)
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An additive NHPP-Based reliability model of wireless sensor networks
- 2014
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Ingår i: Applied Mechanics and Materials. - 9783038351948 ; , s. 3206-3212
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Konferensbidrag (refereegranskat)abstract
- As the Wireless Sensor Networks(WSNs) are widely implemented in various fields recent years, the quality of WSNs has been increasingly concerned. WSNs can usually be divided into sub-nets, which assumed to work or fail independently. Through the failure data of those sub-nets, the additive NHPP model for reliability evaluation is composed, and then the maximum likelihood estimation is applied to estimate the unknown parameters in the model. Finally, the simulation shows that the additive NHPP model is better than general NHPP model under certain circumstances.
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