| 1. |
- Andersson, Mattias, 1980-, et al.
(författare)
-
Equivocation of Eve using two edge type LDPC codes for the binary erasure wiretap channel
- 2010
-
Ingår i: 2010 Conference Record of the Forty Fourth Asilomar Conference on Signals, Systems and Computers (ASILOMAR). - 9781424497225 ; , s. 2045-2049
-
Konferensbidrag (refereegranskat)abstract
- We consider transmission over a binary erasure wiretap channel using the code construction method introduced by Rathi et al. based on two edge type Low-Density Parity-Check (LDPC) codes and the coset encoding scheme. By generalizing the method of computing conditional entropy for standard LDPC ensembles introduced by Méasson, Montanari, and Urbanke to two edge type LDPC ensembles, we show how the equivocation for the wiretapper can be computed. We find that relatively simple constructions give very good secrecy performance and are close to the secrecy capacity.
|
|
| 2. |
- Andersson, Mattias, 1980-, et al.
(författare)
-
Nonlinear distributed sensing for closed-loop control over Gaussian channels
- 2011
-
Ingår i: Communication Technologies Workshop (Swe-CTW), 2011 IEEE Swedish. - : IEEE conference proceedings. - 9781457718779 ; , s. 19-23
-
Konferensbidrag (refereegranskat)abstract
- A scenario of distributed sensing for networked control systems is considered and a new approach to distributed sensing and transmission is presented. The state process of a scalar first order linear time invariant dynamical system is sensed by a network of wireless sensors, which then instantaneously transmit their measurements to a remotely situated control unit over parallel Gaussian channels. The control unit aims to stabilize the system in mean square sense. The proposed non-linear delay-free sensing and transmission strategy is compared with the well-known amplify-and-forward strategy, using the LQG control cost as a figure of merit. It is demonstrated that the proposed nonlinear scheme outperforms the best linear scheme even when there are only two sensors in the network. The proposed sensing and transmission scheme can be implemented with a reasonable complexity and it is shown to be robust to the uncertainties in the knowledge of the sensors about the statistics of the measurement noise and the channel noise.
|
|
| 3. |
- Andersson, Mattias, et al.
(författare)
-
Polar codes for bidirectional broadcast channels with common and confidential messages
- 2012
-
Ingår i: International Symposium on Wireless Communication Systems (ISWCS), 2012. - : IEEE conference proceedings. - 9781467307604 ; , s. 1014-1018
-
Konferensbidrag (refereegranskat)abstract
- We consider the bidirectional broadcast channel with common and confidential messages. We show that polar codes achieve the capacity of binary input symmetrical bidirectional broadcast channels with confidential messages, if one node's channel is a degraded version of the other node's channel. We also find a new bound on the cardinality of the auxiliary random variable in this setup.
|
|
| 4. |
- Andersson, Mattias, 1980-, et al.
(författare)
-
Secret-key agreement over a non-coherent block-fading MIMO wiretap channel
- 2012
-
Ingår i: Information Theory Workshop (ITW), 2012 IEEE. - : IEEE. - 9781467302234 ; , s. 153-157
-
Konferensbidrag (refereegranskat)abstract
- We study secret-key agreement over a non-coherent block-fading multiple input multiple output (MIMO) wiretap channel. We give an achievable scheme based on training and source emulation and analyze the rate in the high SNR regime. Based on this analysis we find the optimal number of antennas to use for training. Our main result is that if the sum of the number of antennas at Alice and Bob is larger than the coherence time of the channel, the achievable rate does not depend on the number of antennas at Eve. In this case source emulation is not needed, and using only training is optimal. We also consider the case when there is no public channel available. In this case we show that secret-key agreement is still possible by using the wireless channel for discussion, giving the same number of secure degrees of freedom as in the case with a public channel.
|
|
| 5. |
- Andersson, Mattias, et al.
(författare)
-
Secure key agreement over reciprocal fading channels in the low SNR regime
- 2013
-
Ingår i: 2013 IEEE 14th Workshop on Signal Processing Advances in Wireless Communications, SPAWC. - : IEEE. - 9781467355773 ; , s. 674-678
-
Konferensbidrag (refereegranskat)abstract
- We study the low SNR scaling of the non-coherent secret-key agreement capacity over a reciprocal, block-fading channel. For the restricted class of strategies, where one of the nodes is constrained to transmit pilot-only symbols, we show that the secret-key capacity scales as SNR ·log T if T ≤ 1/SNR, where T denotes the coherence period, and as SNR·log(1/SNR) otherwise. Our upper bound is inspired by the genie-aided argument of Borade and Zheng (IT-Trans 2010). Our lower bound is based on bursty communication, channel training, and secret message transmission.
|
|
| 6. |
- Andersson, Tomas, et al.
(författare)
-
Design of n-channel multiple description vector quantizers
- 2005
-
Ingår i: 2005 39th Asilomar Conference on Signals, Systems and Computers. - NEW YORK : IEEE. ; , s. 13-17
-
Konferensbidrag (refereegranskat)abstract
- A new design approach for multiple description vector quantizers over more than two channels is presented. The design is inspired by the concept of channel optimized vector quantization. While most previous works have split the decoder into several independent entities, identifying the appropriate channel model makes it straightforward to implement the multiple description design problem using only one decoder. Our simulation results compare systems with 2, 4 and 8 channels. We demonstrate significant gains over previous designs, as well as over a benchmark scheme based on separate quantization and forward erasure-correcting error control.
|
|
| 7. |
|
|
| 8. |
- Andersson, Tomas, et al.
(författare)
-
Frequency estimation utilizing the Hadamard transform
- 2001
-
Ingår i: 2001 IEEE WORKSHOP ON STATISTICAL SIGNAL PROCESSING PROCEEDINGS. - NEW YORK : IEEE. - 0780370112 ; , s. 409-412
-
Konferensbidrag (refereegranskat)abstract
- Fast analog to digital conversion with only one bit per sample does not only make high sampling rates possible but also reduces the required hardware complexity. For short data buffers or block lengths, it has been shown that tone frequency estimators can be implemented by a simple table look-up. In this paper we present an analysis of such tables using the Hadamard transform. As an outcome of the analysis, we propose a class of nonlinear estimators of low complexity. Their performance is evaluated using numerical simulations. Comparisons are made with the proper Cramer-Rao bound and with the table look-up approach.
|
|
| 9. |
- Andersson, Tomas, et al.
(författare)
-
Multiple description image coding based on multi-stage vector quantization
- 2007
-
Ingår i: CONFERENCE RECORD OF THE FORTY-FIRST ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS & COMPUTERS. - NEW YORK : IEEE. ; , s. 243-246
-
Konferensbidrag (refereegranskat)abstract
- A new design approach for multiple description coding, based on multi-stage vector quantizers, is presented. The design is not limited to systems with two descriptions, but is also well suited for the n-descriptions case. Inspired by the concept of channel optimized vector quantization, the design can easily be tailored to suit different erasure channels, e.g. packet erasure channels with memory (burst-losses). The optimization procedure used in the design takes a sample-iterative approach. All stage codebooks; are updated simultaneously for each vector in the training database. The resulting algorithm has the behaviour of a simulated annealing algorithm, with several good properties, e.g. it usually provides codebooks with good index assignments. Image results are presented for systems with 2 and 4 channels. The image coder is based on a subband transform followed by 64-dimensional vector quantization, to illustrate the capacity of the design to handle large problem sizes.
|
|
| 10. |
- Bao, Lei, et al.
(författare)
-
A scheme for joint quantization, error protection and feedback control over noisy channels
- 2007
-
Ingår i: 2007 AMERICAN CONTROL CONFERENCE, VOLS 1-13. - : IEEE. - 9781424409884 ; , s. 2456-2461
-
Konferensbidrag (refereegranskat)abstract
- We study a closed-loop scalar control system with feedback transmitted over a discrete noisy channel. For this problem, we propose a joint design of the state measurement quantization, protection against channel errors, and control. The goal is to minimize a linear quadratic cost function over a finite horizon. In particular we focus on a special case where we verify that certainty equivalence holds, and for this case we design joint source-channel encoder and decoder/estimator pairs. The proposed algorithm leads to a practically feasible design of time-varying non-uniform quantization and control. Numerical results demonstrate the promising performance obtained by employing the proposed iterative optimization algorithm.
|
|
