1,381 results
Search Results
2. Optimal beamforming in MISO cognitive channels with degraded message sets
- Author
-
Jing Lv, Adrian Kliks, Ragnar Thobaben, Eduard A. Jorswieck, and Ricardo Blasco-Serrano
- Subjects
Beamforming ,Mathematical optimization ,business.industry ,Computer science ,Transmitter ,Cognition ,Computer simulation ,Telekommunikation ,Cognitive radio ,Telecommunications ,Wireless telecommunication systems ,Dirty paper coding ,business ,Communication channel - Abstract
In this paper we consider the coexistence of a single-input single-output (SISO) primary link with a multiple-input single-output (MISO) secondary user pair that has non-causal knowledge of the primary message. We study an achievable rate region that exploits this knowledge by combining selfless relaying to maintain the rate supported by the primary link with dirty paper coding to pre-cancel the interference at the secondary receiver. We find the optimal choice of power allocation between these operating modes at the secondary transmitter as well as the optimal beamforming vectors. Moreover, we address the robustness of the solution to uncertainties in the channel knowledge. Finally, we show by numerical evaluation the gains obtained due to the additional knowledge of the primary message. QC 20120905
- Published
- 2012
3. Modulation for interference avoidance on the AWGN channel
- Author
-
Du, Jinfeng
- Subjects
interference avoidance ,dirty paper coding ,Costa precoding ,Data_CODINGANDINFORMATIONTHEORY ,Tomlinson-Harashima precoding ,Electrical Engineering, Electronic Engineering, Information Engineering ,Elektroteknik och elektronik ,Computer Science::Information Theory - Abstract
Theoretic results have shown that the capacity of a channel does not decrease if the receiver observes the transmitted signal in the presence of interference, provided that the transmitter knows this interference non-causally. That is, if the transmitter has non-causal access to the interference, by using proper precoding this interference could be “avoided” (as if it were not present) under the same transmit power constraint. It indicates that lossless (in the sense of capacity) precoding is theoretically possible at any signal-to-noise-ratio (SNR). This is of special interest in digital watermarking, transmission for ISI channels as well as for MIMO broadcast channels. Recent research has elegantly demonstrated the (near) achievability of this “existence-type” result, while the complexity is notable. An interesting question is what one can do when very little extra complexity is permitted. This thesis treats such special cases of this problem in order to shed some light on this question. In the AWGN channel with additive interference, an optimum modulator is designed under the constraint of a binary signaling alphabet with binary interference.Tomlinson-Harashima precoding (THP), which is originally proposed for ISI channels, is improved by picking up optimized parameters and then taken as a benchmark. Simulation results show that the Optimum Modulator always outperforms the THP with optimized parameters. The difference in performance, in terms of mutual information between channel input and output as well as coded bit error rate with Turbo codes, is significant in many scenarios.
- Published
- 2006
4. An investigation on mutual information for the linear predictive system and the extrapolation of speech signals
- Abstract
Mutual information (MI) is an important information theoretic concept which has many applications in telecommunications, in blind source separation, and in machine learning. More recently, it has been also employed for the instrumental assessment of speech intelligibility where traditionally correlation based measures are used. In this paper, we address the difference between MI and correlation from the viewpoint of discovering dependencies between variables in the context of speech signals. We perform our investigation by considering the linear predictive approximation and the extrapolation of speech signals as examples. We compare a parametric MI estimation approach based on a Gaussian mixture model (GMM) with the k-nearest neighbor (KNN) approach which is a well-known non-parametric method available to estimate the MI. We show that the GMM-based MI estimator leads to more consistent results. © 2020 Sprachkommunikation - 10. ITG-Fachtagung. All rights reserved., QC 20201202
- Published
- 2020
5. Delay and Stability Analysis of Caching in Heterogeneous Cellular Networks
- Abstract
In this paper, we propose a general delay and stability performance analysis in Heterogeneous Cellular Caching Networks (HCCNs), based on queuing theory. We introduce new performance metrics in HCCNs and propose an optimization problem which minimizes the average experienced delay for users by ensuring the stability of the network. In addition, from the design perspective, we address the problem of finding the minimum cache size for the small cell base stations (SBSs) for having a tolerable average delay and also a stable network. Finally, the analytic expressions derived in this paper are validated through real trace-driven experiments on traffic of YouTube video requests., QC 20161209
- Published
- 2016
- Full Text
- View/download PDF
6. Wiretap Codes for Secure Multi-Party Computation
- Abstract
In this paper, we propose a new secret sharing scheme for secure multi-party computation. We present a general framework that allows us to construct efficient secret sharing schemes from channel coding techniques for the wiretap channel. The resulting schemes can be employed to securely calculate linear functions of data that are distributed in a network without leaking any information on the data except the desired result. For the examples considered in this paper, our schemes minimize the communication overhead while keeping the data perfectly secure. Compared to conventional schemes, for which the communication overhead grows quadratically in the number of clients in the considered scenarios, the communication overhead for our approach grows only linearly with the number of clients. This property is maintained even if our secret sharing scheme is set up to introduce redundancy in order to compensate for losses of secret shares. While we only consider the case of passive eavesdroppers and implementations based on nested Reed-Solomon codes in this paper, the proposed framework can also be applied in other cases (e.g., when clients tamper with the data) by taking into account the effects of attacks in the design of the underlying wiretap code., QC 20150521
- Published
- 2014
- Full Text
- View/download PDF
7. Wiretap Codes for Secure Multi-Party Computation
- Abstract
In this paper, we propose a new secret sharing scheme for secure multi-party computation. We present a general framework that allows us to construct efficient secret sharing schemes from channel coding techniques for the wiretap channel. The resulting schemes can be employed to securely calculate linear functions of data that are distributed in a network without leaking any information on the data except the desired result. For the examples considered in this paper, our schemes minimize the communication overhead while keeping the data perfectly secure. Compared to conventional schemes, for which the communication overhead grows quadratically in the number of clients in the considered scenarios, the communication overhead for our approach grows only linearly with the number of clients. This property is maintained even if our secret sharing scheme is set up to introduce redundancy in order to compensate for losses of secret shares. While we only consider the case of passive eavesdroppers and implementations based on nested Reed-Solomon codes in this paper, the proposed framework can also be applied in other cases (e.g., when clients tamper with the data) by taking into account the effects of attacks in the design of the underlying wiretap code., QC 20150521
- Published
- 2014
- Full Text
- View/download PDF
8. Statistical methods for inter-view depth enhancement
- Abstract
This paper briefly presents and evaluates recent advances in statistical methods for improving inter-view inconsistency in multiview depth imagery. View synthesis is vital in free-viewpoint television in order to allow viewers to move freely in a dynamic scene. Here, depth image-based rendering plays a pivotal role by synthesizing an arbitrary number of novel views by using a subset of captured views and corresponding depth maps only. Usually, each depth map is estimated individually at different viewpoints by stereo matching and, hence, shows lack of inter-view consistency. This lack of consistency affects the quality of view synthesis negatively. This paper discusses two different approaches to enhance the inter-view depth consistency. The first one uses generative models based on multiview color and depth classification to assign a probabilistic weight to each depth pixel. The weighted depth pixels are utilized to enhance depth maps. The second one performs inter-view consistency testing in depth difference space to enhance the depth maps at multiple viewpoints. We comparatively evaluate these two methods and discuss their pros and cons for future work., QC 20150109
- Published
- 2014
- Full Text
- View/download PDF
9. Wiretap Codes for Secure Multi-Party Computation
- Abstract
In this paper, we propose a new secret sharing scheme for secure multi-party computation. We present a general framework that allows us to construct efficient secret sharing schemes from channel coding techniques for the wiretap channel. The resulting schemes can be employed to securely calculate linear functions of data that are distributed in a network without leaking any information on the data except the desired result. For the examples considered in this paper, our schemes minimize the communication overhead while keeping the data perfectly secure. Compared to conventional schemes, for which the communication overhead grows quadratically in the number of clients in the considered scenarios, the communication overhead for our approach grows only linearly with the number of clients. This property is maintained even if our secret sharing scheme is set up to introduce redundancy in order to compensate for losses of secret shares. While we only consider the case of passive eavesdroppers and implementations based on nested Reed-Solomon codes in this paper, the proposed framework can also be applied in other cases (e.g., when clients tamper with the data) by taking into account the effects of attacks in the design of the underlying wiretap code., QC 20150521
- Published
- 2014
- Full Text
- View/download PDF
10. Wiretap Codes for Secure Multi-Party Computation
- Abstract
In this paper, we propose a new secret sharing scheme for secure multi-party computation. We present a general framework that allows us to construct efficient secret sharing schemes from channel coding techniques for the wiretap channel. The resulting schemes can be employed to securely calculate linear functions of data that are distributed in a network without leaking any information on the data except the desired result. For the examples considered in this paper, our schemes minimize the communication overhead while keeping the data perfectly secure. Compared to conventional schemes, for which the communication overhead grows quadratically in the number of clients in the considered scenarios, the communication overhead for our approach grows only linearly with the number of clients. This property is maintained even if our secret sharing scheme is set up to introduce redundancy in order to compensate for losses of secret shares. While we only consider the case of passive eavesdroppers and implementations based on nested Reed-Solomon codes in this paper, the proposed framework can also be applied in other cases (e.g., when clients tamper with the data) by taking into account the effects of attacks in the design of the underlying wiretap code., QC 20150521
- Published
- 2014
- Full Text
- View/download PDF
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.