Semantic Coding: Partial Transmission

Shannon wrote in 1948: rdquoThe semantic aspects of communication are irrelevant to the engineering problemrdquo. He demonstrated indeed that the information generated by a source depends only on its statistics and not on the meaning of the source output. The authors derived the fundamental limits for semantic compaction, transmission and compression systems recently. These systems have the property that the codewords are semantic however, i.e. close to the source sequences. In the present article we determine the minimum distortion for semantic partial transmission systems. In these systems only a quantized version of each source source symbol is transmitted to the receiver. It should be noted that our achievability proof is based on weak instead of strong typicality. This is unusual for Gelfand-Pinsker [1980] related setups as e.g. semantic coding and embedding

Semantic Coding: Partial Transmission

Shannon wrote in 1948: rdquoThe semantic aspects of communication are irrelevant to the engineering problemrdquo. He demonstrated indeed that the information generated by a source depends only on its statistics and not on the meaning of the source output. The authors derived the fundamental limits for semantic compaction, transmission and compression systems recently. These systems have the property that the codewords are semantic however, i.e. close to the source sequences. In the present article we determine the minimum distortion for semantic partial transmission systems. In these systems only a quantized version of each source source symbol is transmitted to the receiver. It should be noted that our achievability proof is based on weak instead of strong typicality. This is unusual for Gelfand-Pinsker [1980] related setups as e.g. semantic coding and embedding

Secret key watermarking with changing keys

We consider a digital watermarking application where multiple parties can embed additional information using their watermark embedder. These parties are not supposed to influence each other and each watermark detector needs to be able to decode the information embedded by any of the embedder systems. One approach would be to use a single secret key and to assign part of the payload to identify the particular embedder. However, it is generally accepted that for security reasons, each embedder should better have its own secret key. A major drawback of this last approach is related to the detector implementation complexity, which increases linearly with the number of embedders. It is shown that this drawback can be overcome by changing the key in the watermarking system dependant on features of the incoming signal

Videodensitometric methods for cardiac output measurements

Cardiac output is often measured by indicator dilution techniques, usually based on dye or cold saline injections. Developments of more stable ultrasound contrast agents (UCA) are leading to new noninvasive indicator dilution methods. However, several problems concerning the interpretation of dilution curves as detected by ultrasound transducers have arisen. This paper presents a method for blood flow measurements based on UCA dilution. Dilution curves are determined by real-time densitometric analysis of the video output of an ultrasound scanner and are automatically fitted by the Local Density Random Walk model. A new fitting algorithm based on multiple linear regression is developed. Calibration, that is, the relation between videodensity and UCA concentration, is modelled by in vitro experimentation. The flow measurement system is validated by in vitro perfusion of SonoVue contrast agent. The results show an accurate dilution curve fit and flow estimation with determination coefficient larger than 0.95 and 0.99, respectively

On Counteracting Byzantine Attacks in Network Coded Peer-to-Peer Networks

Random linear network coding can be used in peer-to-peer networks to increase the efficiency of content distribution and distributed storage. However, these systems are particularly susceptible to Byzantine attacks. We quantify the impact of Byzantine attacks on the coded system by evaluating the probability that a receiver node fails to correctly recover a file. We show that even for a small probability of attack, the system fails with overwhelming probability. We then propose a novel signature scheme that allows packet-level Byzantine detection. This scheme allows one-hop containment of the contamination, and saves bandwidth by allowing nodes to detect and drop the contaminated packets. We compare the net cost of our signature scheme with various other Byzantine schemes, and show that when the probability of Byzantine attacks is high, our scheme is the most bandwidth efficient.Comment: 26 pages, 9 figures, Submitted to IEEE Journal on Selected Areas in Communications (JSAC) "Mission Critical Networking

Recordable Storage Medium With Protected Data Area

The invention relates to a method of storing data on a rewritable data storage medium, to a corresponding storage medium, to a corresponding recording apparatus and to a corresponding playback apparatus. Copy-protective measures require that on rewritable storage media some data must be stored which shall not be modifiable or erasable by consumer end products. A practical problem is the storage of large quantities of such data in a fixed data area. Typically the capacity is limited to a few bits. Meanwhile the amount of copy protection data that needs to be stored may well exceed the storage capacity available in the read-only fixed data area. The invention therefore proposes to write the copy protection data as system data in the recordable data area (4), e.g. as part of the formatting of the medium (1). A cryptographic summary is computed and also stored in the recordable data area (32) or in the fixed data area (2) such that a cryptographic relationship between the fixed data area (2) and the system data area (3) is provided. A playback or replay apparatus will only accept a storage medium with a valid combination of copy protection data and fixed data

Recordable Storage Medium With Protected Data Area

The invention relates to a method of storing data on a rewritable data storage medium, to a corresponding storage medium, to a corresponding recording apparatus and to a corresponding playback apparatus. Copy-protective measures require that on rewritable storage media some data must be stored which shall not be modifiable or erasable by consumer end products. A practical problem is the storage of large quantities of such data in a fixed data area. Typically the capacity is limited to a few bits. Meanwhile the amount of copy protection data that needs to be stored may well exceed the storage capacity available in the read-only fixed data area. The invention therefore proposes to write the copy protection data as system data in the recordable data area (4), e.g. as part of the formatting of the medium (1). A cryptographic summary is computed and also stored in the recordable data area (32) or in the fixed data area (2) such that a cryptographic relationship between the fixed data area (2) and the system data area (3) is provided. A playback or replay apparatus will only accept a storage medium with a valid combination of copy protection data and fixed data