Lucent Technologies Inc.

Massachusetts Institute of Technology

Agere Systems Guardian Corp.

Alcatel Lucent

Brian Chen

Carl-Erik Wilhelm Sundberg

Gregory W Wornell

The invention provides optimal complementary punctured convolutional codes for coding information bits in a communication system. In an illustrative embodiment, an optimal pair of complementary punctured codes is selected from a set of potential code pairs. The set of potential code pairs includes all non-catastrophic complementary punctured code pairs which combine to produce to a specified full-bandwidth code, and thus includes both equivalent and non-equivalent complementary codes. The optimal code pair may be selected, for example, as the pair of equivalent or non-equivalent codes which has the best free Hamming distance and minimum information error weight of all the pairs in the set. In addition, the invention provides both rate-compatible and rate-incompatible codes suitable for use in providing unequal error protection (UEP) for different classes of information bits. The invention further provides optimal bit assignment techniques for use in digital audio broadcasting or other applications in which digital information is transmitted on subcarriers in both an upper and a lower sideband of an analog carrier.

Optimal complementary punctured convolutional codes

In a communications system implementing an in-band on channel AM (IBOC-AM) (also known as &ldquo;hybrid IBOC-AM&rdquo;) scheme, digitally modulated signals are transmitted in a 30 kHz digital band centered at an analog host AM carrier frequency f . The host AM carrier is assigned to the geographic area served by the communications system for AM radio broadcast. It is likely that a similar IBOC-AM scheme is implemented in an adjacent area which is assigned a second analog host AM carrier having a frequency which is either 20 kHz higher or lower than f . In that case, the transmission of the digitally modulated signals are interfered by a similar transmission in the adjacent area. The interference is known as &ldquo;second adjacent channel interference.&rdquo; To reduce such interference, selected power profiles in accordance with the invention are used to allocate the relative transmission power to the digitally modulated signals in the digital band.

Technique for communicating digitally modulated signals over an amplitude-modulation frequency band

A system, method, and product provide distortion compensation when watermarking a host signal with a watemark signal. The watermark signal includes watermark-signal components having watermark-signal values, and the host signal includes host-signal components having host-signal values. A system includes an ensemble designator that designates a plurality of embedding generators, each corresponding to a single watermark-signal value of a co-processed group of one or more watermark-signal components. Also included is an embedding value generator that generates embedding values by each embedding generator. The system also has a point coder that sets at least one host-signal value of one or more selected host-signal components to a first embedding value to form a composite-signal value. A distortion compensator modifies at least one composite signal value. The distortion compensator includes a difference signal generator that generates a difference signal component having a first difference-signal value that is the difference between a host-signal value and its corresponding composite-signal value. The distortion compensator also includes a difference signal processor that scales the difference-signal value by a scaling factor, A distortion compensation combiner then generates a distortion-compensated composite signal based on the scaled difference-signal value and the composite-signal value. The distortion compensator may modify the composite signal value based on the number of possible watermark signal values to be embedded, a watermark-induced distortion level, an expected channel-induced distortion level, and a reliability of extracting the watermark signal.

System, method, and product for distortion-compensated information embedding using an ensemble of non-intersecting embedding generators

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.

System, method, and product for information embedding using an ensemble of non-intersecting embedding generators

Optimal complement punctured convolutional codes for use in digital audio broadcasting and other applications

The likelihood of significant errors in a decoded sequence is determined based on at least one criterion that is both extrinsic and intrinsic to the decoded sequence. In particular, this determination is preferably made by comparing a signal corresponding to the decoded sequence with a so-called error mitigation signal.

Screening for errors in data transmission systems

A system, method, and product are provided to (1) pre-process one or more primary signals to generate a transformed host-signal and/or a transformed watermark-signal; (2) embed one or more watermarked signals and/or transformed watermark signals into a host signal and/or the transformed 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. An embedding value may be the closest of all embedding values generated by an embedding generator to a host-signal value that is to be quantized. Embedding values may be based on a trellis-coded pre-determined relationship between embedding values, or on predetermined relationships based on lattice quantization. The method may also include a fourth step of extracting the first watermark-signal value from a composite-signal value to form a reconstructed watermark-signal value. The present invention may also implement adaptive embedding and, in some implementations, super-rate quantization. For example, the invention may be a system that includes an ensemble designator that designates a plurality of adaptive embedding generators, each corresponding to a single watermark-signal value of a co-processed group of one or more watermark-signal components. Also included in this implementation is an adaptive embedding value generator that generates, by each adaptive embedding generator, a plurality of adaptive embedding values.

System method, and product for information embedding using an ensemble of non-intersecting embedding generators

In a system for simulcasting digitally modulated and analog FM signals over the same FM frequency band, the effect of the analog FM signal on the digitally modulated signal in the simulcast is calculated and canceled from the latter signal before its transmission. As a result, the digital transmission is free from interference from the analog FM signal. Moreover, the digital transmission is achieved by adaptively inserting a time varying number of carriers modulated by digital data into the FM band. The carriers are selected frame by frame to control their interference with the analog FM signal. In accordance with the invention, the carriers are selected in a predetermined order, and in a preferred embodiment grouped contiguously with one another in the FM band. As a result, the rate of control information required to identify the inserted carriers to a receiver is advantageously low.

Band insertion and precancellation technique for simultaneous communications of analog frequency-modulated and digitally modulated signals

For a transmission system in which (a) a received sequence of symbols is processed by an inner decoder followed by an outer decoder and (b) the inner decoder is capable of providing to the outer decoder more than one output sequence corresponding to the received sequence, the decoded sequence released by the outer decoder is screened for errors undetected by the outer decoder, if a predetermined criterion is satisfied.

Screening for undetected errors in data transmission systems

List Viterbi decoding of a block of data that has been encoded with a tailbiting convolutional code is provided for in a manner that takes advantage of decoder knowledge that starting and terminating states are identical but data-dependent and thus unknown to the receiver.

List Viterbi algorithms for tailbiting convolutional codes

List Viterbi algorithms are provided for decoding blocks or frames of convolutional coded information transmitted and received in a continuous mode, i.e., without blockwise termination with a tail. Viterbi decoding is utilized to estimate, for each respective one of a sequence of blocks of symbols, a terminating (and optionally a starting) state which is(are) used in subsequent application of a List Viterbi algorithm. The path memory should be sufficient to enable both the starting state and the terminating state used by the subsequent List Viterbi decoding to be estimated with reasonable accuracy and at the same time to keep track of the best paths between those states.

Growing community of inventors

Somerville, MA, United States of America

Brian Chen