Wireless optical communication in illumination systems

\u3cp\u3eElectric lighting is pervasive and with LED lighting the ability arises to modulate light. This paper will address some challenges in using illumination products for Optical Wireless Communication (OWC). Electronic LED drivers are going through extreme cost down and have to adhere to efficiency and other requirements that are not easily compatible with OWC. This paper also validates the use of traditional water pouring for OWC channels in which the transmit power consumed for modulation is a nonlinear function of the emitted energy per communication bit.\u3c/p\u3

The “ticket” concept for copy control based on embedded signalling

\u3cp\u3eThis application-oriented paper discusses the use of electronic watermarks (also called embedded signaling) for copy control. Playback Control and Copy-Once are described. The ticket concept' is presented to provide these functionalities. Although the ticket shows similarities with a digital signature, there are essential differences. For instance, the ticket allows typical modifications of the content, which are common practice in transmission, storage and presentation of video. The concept is part of a proposal currently under investigation for standardization of DVD/CPTWG copy control. This paper also compares the ticket concept with other solutions, such as embedding a secondary mark at the recorder and using a signature scheme.\u3c/p\u3

Virtual-antenna receiver

The invention is directed to the reception of high rate radio signals (for example DVB-T signals) while the receiver is moving at a high speed (for example in or with a car). Two or more antennas (12, 16) are closely spaced and arranged behind each other in the direction of motion (v) for receiving the radio signals. A signal is obtained which represents a virtual antenna (26) that is at least temporarily stationary with respect to the environment, despite the movement of the receiver. The receiving signal of the virtual antenna (26) suffers at least less distortions than a signal received by one of the first and second antennas (12, 16). In accordance with the invention the signal which represents the virtual antenna (26) is obtained under the control of a feedback signal (SYNC) of the receiver

The “ticket” concept for copy control based on embedded signalling

\u3cp\u3eThis application-oriented paper discusses the use of electronic watermarks (also called embedded signaling) for copy control. Playback Control and Copy-Once are described. The ticket concept' is presented to provide these functionalities. Although the ticket shows similarities with a digital signature, there are essential differences. For instance, the ticket allows typical modifications of the content, which are common practice in transmission, storage and presentation of video. The concept is part of a proposal currently under investigation for standardization of DVD/CPTWG copy control. This paper also compares the ticket concept with other solutions, such as embedding a secondary mark at the recorder and using a signature scheme.\u3c/p\u3

Slotted ALOHA land-mobile radio networks with site diversity

\u3cp\u3eAn analytical method for investigating slotted ALOHA land-mobile networks is presented. The probability of successful reception and throughput is assessed for a single base station, taking account of contending transmissions and receiver noise. Receiver capture is assumed to occur if the received signal power exceeds the joint interference power by a certain margin, called the receiver threshold. Rayleigh fading and UHF groundwave propagation are considered. Results are extended for a cellular network considering the interference from packet transmissions in other (co-channel) cells. It is seen that in packet-switched cellular nets, frequency re-use distances may be substantially smaller than in circuit-switched (CW) telephony networks, where each cell has to be safeguarded continuously from co-channel interference. Moreover, a technique to assess the throughput of ALOHA networks with multiple, geographically-separated base stations is presented and numerical results are given for uniform Poisson-distributed packet transmissions in the service area.\u3c/p\u3

Detecting a watermark embedded in an information signal

A watermark embedded in an information signal is detected by correlating said information signal with a plurality of watermarks Wj(n). The respective amounts of correlation C(i,j) are then evaluated to determine the watermark embedded in the signal xi(n). The invention provides a significant improvement of the detection by predictive filtering (25) the information signal and/or predictive filtering (26) the applied watermark prior to the process of correlating the signals

Diversity receiver having cross coupled channel parameter estimation

A diversity receiver has multiple antenna receiving branches. Each branch has means for estimating at least a receiving channel parameter, and the channel parameter estimating means in one branch are coupled to the channel parameter estimating means in an other branch. This way at least a part of the channel parameter estimate in the one branch is used as an aid for estimating at least a receiving channel parameter in the other branch. This saves processing time and processing power in the diversity receiver, and even results in a higher accuracy when selecting the best antenna and receiving branch

Performance analysis of synchronous MC-CDMA in mobile Rayleigh channel with both delay and Doppler spreads

\u3cp\u3eRapid time variations of the mobile communication channel have a dramatic effect on the performance of multicarrier modulation. This paper models the Doppler spread and computes its effect on the bit error rate (BER) for multicarrier code division multiple access (MC-CDMA) transmission and compares it to orthogonal frequency division multiplexing (OFDM). Also, we evaluate the transmission capacity per subcarrier to quantify the potential for MC-CDMA and (coded-) OFDM. We focus on linear receivers, in particular those using the minimum mean-square error (MMSE) criterion. Our channel and system models allow the computation of analytical performance results. Simulations verify some commonly used, yet critical assumptions.\u3c/p\u3

System for secure storage

A system (100) comprising read means (112) for reading content data and control logic data from a storage medium (101), the control logic data being uniquely linked to the storage medium (101), processing means (113-117), for processing the content data and feeding the processed content data to an output, and control means (120) for executing the control logic data and for controlling the processing means (113-117) in accordance with the control logic data being executed. The link is preferably realized by variations in a physical parameter of the storage medium (101) that exhibit a modulation pattern representing a necessary parameter for obtaining access to the control logic data. Alternatively, the link is realized by an integrated circuit (201) on the storage medium (101) which contains the necessary parameter. The necessary parameter may comprise a decryption key or authentication data