Global ETD Search

71	Information Leakage Neutralization for the Multi-Antenna Non-Regenerative Relay-Assisted Multi-Carrier Interference Channel Ho, Zuleita, Jorswieck, Eduard, Engelmann, Sabrina January 2013 (has links) In heterogeneous dense networks where spectrum is shared, users' privacy remains one of the major challenges. On a multi-antenna relay-assisted multi-carrier interference channel, each user shares the spectral and spatial resources with all other users. When the receivers are not only interested in their own signals but also in eavesdropping other users' signals, the cross talk on the spectral and spatial channels becomes information leakage. In this paper, we propose a novel secrecy rate enhancing relay strategy that utilizes both spectral and spatial resources, termed as information leakage neutralization. To this end, the relay matrix is chosen such that the effective channel from the transmitter to the colluding eavesdropper is equal to the negative of the effective channel over the relay to the colluding eavesdropper and thus the information leakage to zero. Interestingly, the optimal relay matrix in general is not block-diagonal which encourages users' encoding over the frequency channels. We proposed two information leakage neutralization strategies, namely efficient information leakage neutralization (EFFIN) and local-optimized information leakage neutralization (LOPTIN). EFFIN provides a simple and efficient design of relay processing matrix and precoding matrices at the transmitters in the scenario of limited power and computational resources. LOPTIN, despite its higher complexity, provides a better sum secrecy rate performance by optimizing the relay processing matrix and the precoding matrices jointly. The proposed methods are shown to improve the sum secrecy rates over several state-of-the-art baseline methods. info:eu-repo/classification/ddc/620 ddc:620 info:eu-repo/classification/ddc/621.3 ddc:621.3
72	Precoder Design Based on Mutual Information for Non-orthogonal Amplify and Forward Wireless Relay Networks Syed, Tamseel Mahmood 09 June 2014 (has links) No description available. Computer Engineering Design Electrical Engineering Engineering Literature Systems Design Systems Science Theoretical Mathematics Cooperative Communication wireless network reliability data-rate NAF space-time code non-orthogonal amplify and forward information theory mutual information PEP precoder SNR closed form symbol grouping receiver complexity Tamseel Syed
73	Performance evaluation and protocol design of fixed-rate and rateless coded relaying networks Nikjah, Reza 06 1900 (has links) The importance of cooperative relaying communication in substituting for, or complementing, multiantenna systems is described, and a brief literature review is presented. Amplify-and-forward (AF) and decode-and-forward (DF) relaying are investigated and compared for a dual-hop relay channel. The optimal strategy, source and relay optimal power allocation, and maximum cooperative gain are determined for the relay channel. It is shown that while DF relaying is preferable to AF relaying for strong source-relay links, AF relaying leads to more gain for strong source-destination or relay-destination links. Superimposed and selection AF relaying are investigated for multirelay, dual-hop relaying. Selection AF relaying is shown to be globally strictly outage suboptimal. A necessary condition for the selection AF outage optimality, and an upper bound on the probability of this optimality are obtained. A near-optimal power allocation scheme is derived for superimposed AF relaying. The maximum instantaneous rates, outage probabilities, and average capacities of multirelay, dual-hop relaying schemes are obtained for superimposed, selection, and orthogonal DF relaying, each with parallel channel cooperation (PCC) or repetition-based cooperation (RC). It is observed that the PCC over RC gain can be as much as 4 dB for the outage probabilities and 8.5 dB for the average capacities. Increasing the number of relays deteriorates the capacity performance of orthogonal relaying, but improves the performances of the other schemes. The application of rateless codes to DF relaying networks is studied by investigating three single-relay protocols, one of which is new, and three novel, low complexity multirelay protocols for dual-hop networks. The maximum rate and minimum energy per bit and per symbol are derived for the single-relay protocols under a peak power and an average power constraint. The long-term average rate and energy per bit, and relay-to-source usage ratio (RSUR), a new performance measure, are evaluated for the single-relay and multirelay protocols. The new single-relay protocol is the most energy efficient single-relay scheme in most cases. All the multirelay protocols exhibit near-optimal rate performances, but are vastly different in the RSUR. Several future research directions for fixed-rate and rateless coded cooperative systems, and frameworks for comparing these systems, are suggested. / Communications acknowledgment signals amplify-and-forward relaying average capacity average power constraint bit error rate cooperative gain cooperative communication decode-and-forward relaying degree of freedom direct transmission distributed space-time coding dual-hop relaying energy efficiency energy per bit energy per symbol feedback communication fixed-rate coded relaying fixed-rate codes fixed-rate coding large SNR approximation maximal ratio combining maximum achievable rates maximum likelihood multiple access channels mutual information nonconcave fractional programming numerical optimization optimal power allocation orthogonal relaying outage optimality outage probability parallel channel coding peak power constraint power allocation schemes power fairness protocol design rateless coded relaying rateless codes rate efficiency rateless coding Rayleigh fading relay-to-source usage ratio relaying networks repetition coding selection relaying single-hop communication superimposed relaying symbol error rate
74	Performance evaluation and protocol design of fixed-rate and rateless coded relaying networks Nikjah, Reza Unknown Date No description available. acknowledgment signals amplify-and-forward relaying average capacity average power constraint bit error rate cooperative gain cooperative communication decode-and-forward relaying degree of freedom direct transmission distributed space-time coding dual-hop relaying energy efficiency energy per bit energy per symbol feedback communication fixed-rate coded relaying fixed-rate codes fixed-rate coding large SNR approximation maximal ratio combining maximum achievable rates maximum likelihood multiple access channels mutual information nonconcave fractional programming numerical optimization optimal power allocation orthogonal relaying outage optimality outage probability parallel channel coding peak power constraint power allocation schemes power fairness protocol design rateless coded relaying rateless codes rate efficiency rateless coding Rayleigh fading relay-to-source usage ratio relaying networks repetition coding selection relaying single-hop communication superimposed relaying symbol error rate

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