摘要:
A powerful new class of methods for encoding digital data for reliable transmission over unreliable communication channels is described. With this method, the message bits are divided into multiple submessages and the bits in each layer are encoded using a standard error correction code to provide a plurality of subcodewords. A first linear transformation is applied to each of the subcodewords. The so-transformed subcodewords from the different submessages are then combined to form a first redundancy block to be transmitted. Additional redundancy blocks are generated by repeating this process on the same message but with jointly related nonidentical sets of linear transformations. The result is a set of codewords for each message which are then used to generate a transmitted waveform in one of several different ways, depending upon the application. For example, the codewords can be used in sequence (temporally) to form a rateless code for transmission over channels of unknown quality, in which case a receiver accumulates as many of the codewords as are necessary to successfully decode. As another example, the codewords can be spatially distributed if the channel has multiple-inputs, as would be the case in a multi-antenna system. As still another example, the codewords can be distributed over subchannels in a frequency-division multiplexing system.
摘要:
A block-iterative equalizer is adapted for use in contemporary digital communication system receivers. In a preferred embodiment, data received over a communication channel is processed by a linear feed-forward filter and the resulting filtered signal is provided to a slicer which makes a first set of tentative symbol decisions. During later iterations, the same received data is processed by the linear feed-forward filter, the feed-forward filter parameters being modified at each iteration based on the received data and the tentative decisions are themselves filtered by a second, “feed-back” filter and used to improve the tentative decisions.
摘要:
A powerful new class of methods for encoding digital data for reliable transmission over unreliable communication channels is described. With this method, the message bits are divided into multiple submessages and the bits in each layer are encoded using a standard error correction code to provide a plurality of subcodewords. A first linear transformation is applied to each of the subcodewords. The so-transformed subcodewords from the different submessages are then combined to form a first redundancy block to be transmitted. Additional redundancy blocks are generated by repeating this process on the same message but with jointly related nonidentical sets of linear transformations. The result is a set of codewords for each message which are then used to generate a transmitted waveform in one of several different ways, depending upon the application. For example, the codewords can be used in sequence (temporally) to form a rateless code for transmission over channels of unknown quality, in which case a receiver accumulates as many of the codewords as are necessary to successfully decode. As another example, the codewords can be spatially distributed if the channel has multiple-inputs, as would be the case in a multi-antenna system. As still another example, the codewords can be distributed over subchannels in a frequency-division multiplexing system.
摘要:
Method and apparatus for preparing a message stream of symbols for wireless transmission by pre-coding it through convolution with a characteristic "signature" of predetermined symbols identifying a particular user of the message system. The time duration of the signature should exceed the inter-symbol interval of the message stream in order to reduce the likelihood of error caused by fading in the transmission channel.
摘要:
A system, method, and product are provided to (1) embed a watermark signal into a host signal, thereby generating a composite signal, (2) optionally enable the composite signal to be transmitted over a communication channel, and (3) optionally extract the watermark signal from the transmitted composite signal. In one embodiment, the invention is a method for watermarking a host signal with a watermark signal. The watermark signal is made up of watermark-signal components, each having one of two or more watermark-signal values. The host signal is made up of host-signal components, each having one of two or more host-signal values. The method includes: (1) generating two or more embedding generators, each corresponding to a single watermark-signal value of a co-processed group of one or more watermark-signal components; (2) having each embedding generator generate two or more embedding values, the total of which is referred to as an original embedding-value set such that at least one embedding value generated by one embedding generator is different than any embedding value generated by another embedding generator; and (3) setting a host-signal value of one or more selected host-signal components to an embedding value of a particular embedding generator, thereby forming a composite-signal value, such that the particular embedding generator corresponds to the watermark-signal value of the co-processed group of watermark-signal components, and such that the embedding value of the particular embedding generator is selected based on its proximity to the host-signal value.
摘要:
Transmitting and receiving method and apparatus especially suited to multi-user communication systems such as cellular systems, in which multi-path transmission encounters time-variable fading characteristics in the channel. Pre-coding message stream of symbols by convolution with predetermined signature sequences for respective users enables separation of respective user messages and combats effects of variable fading.
摘要:
Described are techniques for performing lossy encoding. Source data and quality data are received by an encoder. The encoder maps the source data into a compressed representation having a level of distortion in accordance with the quality information. The compressed representation may be decoded without using the quality information.
摘要:
A compression and transmission method and system for use to communicate information from a first device to a second device in a network of devices. First, the first device receives information to be communicated to the second device. Second, the first device compresses the information to be communicated by employing prior information of the first device and prior information of the second device. The compressed information is then transmitted to the second device.
摘要:
A system, method, and product are provided to (1) embed a watermark signal into a host signal, thereby generating a composite signal, (2) optionally enable the composite signal to be transmitted over a communication channel, and (3) optionally extract the watermark signal from the transmitted composite signal. In one embodiment, the invention is a method for watermarking a host signal with a watermark signal. The watermark signal is made up of watermark-signal components, each having one of two or more watermark-signal values. The host signal is made up of host-signal components, each having one of two or more host-signal values. The method includes: (1) generating two or more embedding generators, each corresponding to a single watermark-signal value of a co-processed group of one or more watermark-signal components; (2) having each embedding generator generate two or more embedding values, the total of which is referred to as an original embedding-value set such that at least one embedding value generated by one embedding generator is different than any embedding value generated by another embedding generator; and (3) setting a host-signal value of one or more selected host-signal components to an embedding value of a particular embedding generator, thereby forming a composite-signal value, such that the particular embedding generator corresponds to the watermark-signal value of the co-processed group of watermark-signal components, and such that the embedding value of the particular embedding generator is selected based on its proximity to the host-signal value.
摘要:
Communication over lossy packet networks such as the Internet is hampered by limited bandwidth and packet loss. The present invention provides a path diversity transmission system for improving the quality of communication over a lossy packet network. The path diversity transmission system explicitly sends different subsets of packets over different paths, thereby enabling the end-to-end application to effectively see an average path behavior. Generally, seeing this average path behavior provides better performance than seeing the behavior of any individual random path. For example, the probability that all of the multiple paths are simultaneously congested is much less than the probability that a single path is congested. The resulting path diversity can provide a number of benefits, including enabling real-time multimedia communication and simplifying system design (e.g., error correction system design). Two exemplary architectures for achieving path diversity are described herein. The first architecture is based on source routing, and the second architecture is based on a relay infrastructure. The second architecture routes traffic through semi-intelligent nodes at strategic locations in the Internet, thereby providing a service of improved reliability while leveraging the infrastructure of the Internet.