| 11. |
- Gerbracht, Sabrina, et al.
(författare)
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Non-regenerative two-hop wiretap channels using interference neutralization
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, we analyze the achievable secrecy rates in the two-hop wiretap channel with four nodes, where the transmitter and the receiver have multiple antennas while the relay and the eavesdropper have only a single antenna each. The relay is operating in amplify-and-forward mode and all the channels between the nodes are known perfectly by the transmitter. We discuss different transmission and protection schemes like artificial noise (AN). Furthermore, we introduce interference neutralization (IN) as a new protection scheme. We compare the different schemes regarding the high-SNR slope and the high-SNR power offset and illustrate the performance by simulation results. It is shown analytically as well as by numerical simulations that the high SNR performance of the proposed IN scheme is better than the one of AN.
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| 12. |
- Grotz, Joel, et al.
(författare)
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Applicability Of Interference Processing To DTH Reception
- 2006
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Ingår i: Ninth International Workshop on Signal Processing for Space Communications, September 2006.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Today fixed satellite broadcast reception has to compete efficiently with other means of broadcast content delivery to end-users. The ease of reception is essential to maintain a high penetration rate under more competitive conditions. The introduction of DVB-S2 increases efficiency and allows for a higher throughput or a reduction of the reception equipment requirements. This means that a robust broadcast reception is conceivable with a reduced direct-to-home (DTH) antenna size. The current interference situation at common geostationary broadcast positions dictates the spatial discrimination requirements of common direct-to-home (DTH) reception antennas. A more robust coding rate or a relaxation of the frequency coordination constraints would obviously relax the requirements on the reception front-end but only at the expense of a reduced aggregate efficiency. The use of known interference processing schemes for DTH reception has been investigated under dual reception path scenarios, see [1]. The present work extends the concept by introducing linear pre-processing (LPP) to combine coherent reception paths. These mechanisms will only be practical if the transmitted broadcast signals are compliant with established standards (ie. DVB-S [5] or DVB-S2 [4]). The maximization of the efficiency is a main objective under given reception environments. We show how multi-user detection techniques can increase efficiency and allow reduced antenna size under realistic conditions.
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| 13. |
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| 14. |
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| 15. |
- Jaldén, Joakim, 1976-, et al.
(författare)
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Detection Based on Relaxation in MIMO Systems
- 2008. - 1
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Ingår i: Handbook on Advancements in Smart Antenna Technologies for Wireless Networks. - : Premier Reference Source. - 9781599049885 - 1599049880 ; , s. 308-327
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter takes a closer look at a class of MIMO detention methods, collectively referred to as relaxation detectors. These detectors provide computationally advantageous alternatives to the optimal maximum likelihood detector. Previous analysis of relaxation detectors have mainly focused on the implementation aspects, while resorting to Monte Carlo simulations when it comes to investigating their performance in terms of error probability. The objective of this chapter is to illustrate how the performance of any detector in this class can be readily quantified thought its diversity gain when applied to an i.i.d. Rayleigh fading channel, and to show that the diversity gain is often surprisingly simple to derive based on the geometrical properties of the detector.
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| 16. |
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| 17. |
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| 18. |
- Jöngren, George, et al.
(författare)
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Combining Transmit Antenna Weights with Orthogonal Space-Time Block Coding
- 1999
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Ingår i: Proceedings Nordiskt radioseminarium 1999.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Multiple transmit and receive antennas can be used in wireless systems to acheive high data rate communications. Recently, space-time codes have been developed that utilize some of the capacity available. These codes are developed under the assumption that the transmitter has no knowledge about the channel. However, we consider the case when the transmitter has partial, but not perfect, knowledge about the channel and how toadjust the antenna weights at the transmitter. A criterion is derived that optimally determines the transmit antenna weights when well known block orthogonal space-time codes are used. Simulation results using two transmit antennas are included to demonstrate the performance.
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| 19. |
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| 20. |
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