Abstract: A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with multi-carrier Orthogonal Frequency Division Multiplexing (OFDM) modulation. Space-Time coding techniques improve transmission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. OFDM modulation allows for wideband transmission over frequency selective radio channels. A receiver demodulates the OFDM signal and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values.

Abstract: A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with modulating several streams of the BICM encoded data for transmission over two or more antennas. Space-time coding techniques improve transmission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. A receiver demodulates the received signals and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values. By applying well-known turbo-decoding principles to iteratively demap and decode, the overall receiver performance is significantly improved.

Abstract: In a digital audio broadcast system, to utilize transmission bandwidth efficiently, representations of a stereo audio signal for transmission are generated in accordance with an inventive multidescriptive coding technique. The representations, as generated, are then transmitted through multiple communication channels, respectively. The transmitted representations are received by a receiver where one or more of the representations are selected for recovery of the stereo audio signal. Because of the design of the multidescriptive coding used, the more representations are selected to recover the stereo audio signal, the higher the quality of the recovered signal.

Abstract: The invention provides methods and apparatus for processing information, e.g., audio, video or image information, for transmission in a communication system. In an illustrative embodiment, a joint multiple program coder determines the value of a single-bit or multiple-bit criticality measure, e.g., criticality flag, in a designated interval, e.g., the duration of an audio frame, for each of the programs in a set of multiple programs to be transmitted in the system. The joint multiple program coder allocates a pool of available bits to the programs based at least in part on the determined values of the criticality measures, such that a program with a higher-valued criticality measure in the designated time interval is allocated a greater percentage of the available bits for that interval than another one of the programs with a lower-valued criticality measure. The joint multiple program coder repeats the determination and allocation operations for each of a number of time intervals, e.g.

Abstract: Techniques are disclosed for processing received information in a communication system, such that performance is significantly improved in the presence of certain types of interference, e.g., partial-band interference. In an illustrative embodiment, first and second digital sidebands are transmitted on either side of an AM or FM host carrier signal in a hybrid in-band on-channel (HIBOC) digital audio broadcasting (DAB) system. The compressed digital audio information in the sidebands is encoded using an error correcting code such as a Reed-Solomon (RS) code. A receiver attempts to detect interference within a designated portion of a given one of the sidebands. If the interference is detected, the receiver eliminates the portion of the frequency band from consideration in the decoding process by using a fixed-erasure decoding (FED) technique to decode the error correcting code.

Abstract: 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.

Abstract: A method for providing packet loss recovery in a data packet-based network used for real-time multimedia communications. In accordance with a first illustrative embodiment of the present invention, the information payload associated with a given data packet k is identically copied and appended to data packet k+w (i.e., the information payload is repeated with a delay of w transmitted packets). More generally, the present invention provides a method of coding a sequence of data packets representing a contiguous stream of information, with each data packet comprising, a set of payload information representative of a segment of the stream of information corresponding thereto.

Abstract: Source-coded information from a multi-mode source encoder is channel coded for transmission in a communication system. A multi-mode channel encoder associates a different channel coding error protection profile with each of the modes of the multi-mode source encoder. The channel encoder determines a mode used by the multi-mode source encoder to source code a given frame or other designated portion of the information, and channel codes the source-coded portion of the information utilizing an error protection profile identified at least in part based on the determined mode. A multi-mode channel decoder is operative to hypothesize that a particular one of the modes of the multi-mode source encoder was used to source code the designated portion of the information.

Abstract: Digital information is processed for transmission in a communication system using a hidden puncturing technique. The digital information is encoded using a channel code having at least one puncturing pattern associated therewith. The puncturing pattern is preferably a rate compatible puncturing pattern. In accordance with the invention, there is no puncturing of the channel code applied at a transmitter side of the system. Instead, the resulting channel coded bits are assigned to different sections of a digital sideband or other portion of a frequency spectrum of the system, based at least in part on the puncturing pattern. The coded channel bits are then transmitted through the system in the assigned sections, and can be decoded at different code rates in a receiver of the system depending on which of the sections are used in the decoding process.

Abstract: A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with modulating several streams of the BICM encoded data for transmission over two or more antennas. Space-time coding techniques improve transmission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. A receiver demodulates the received signals and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values. By applying well-known turbo-decoding principles to iteratively demap and decode, the overall receiver performance is significantly improved.

Abstract: A system employs space-time coding characterized at the transmitter by bit-interleaved coded modulation (BICM) combined with multi-carrier Orthogonal Frequency Division Multiplexing (OFDM) modulation. Space-Time coding techniques improve transmission efficiency in radio channels by using multiple transmit and/or receive antennas and coordination of the signaling over these antennas. Bit-interleaved coded modulation provides good diversity gain with higher-order modulation schemes that employ binary convolutional codes. OFDM modulation allows for wideband transmission over frequency selective radio channels. A receiver demodulates the OFDM signal and applies multi-input, multi-output (MIMO) demapping to estimate the BICM encoded bitstream. After deinterleaving of the BICM encoded bitstream, maximum a posteriori (MAP) decoding is applied to the resulting bit stream to generate soft output values.

Abstract: Improved error screening techniques are used in processing digital audio or other types of information received in a digital communication system. Control information associated with a given packet of the received information is identified and compared with a decoding requirement of the packet, in order to control the generation of an error indicator for the packet. More particularly, the error indicator may be generated in response to an inconsistency between the control information and the decoding requirement. For example, the control information may include an indication of packet length that can be compared to a number of bits required to decode the corresponding packet, with any inconsistency between the packet length indication and the number of required bits leading to the generation of an error flag for the packet.

Abstract: Improved channel code configurations for use in transmission of digital audio or other types of information in a digital communication system. The channel code may include an outer channel code, e.g., a cyclic redundancy code (CRC), and an inner channel code, e.g., a complementary punctured pair convolutional (CPPC) code. In accordance with the invention, multiple code words of the outer code are associated with a given packet of the digital information, in accordance with a particular outer code configuration, so as to provide partial error flagging for different portions of the given packet. An information encoder, e.g., a PAC encoder, interacts with an outer code encoder to determine a bit allocation for transmission of packets at a particular bit rate, based at least in part on the outer code configuration.

Abstract: Source-coded information from a multi-mode source encoder is channel coded for transmission in a communication system. A multi-mode channel encoder associates a different channel coding error protection profile with each of the modes of the multi-mode source encoder. The channel encoder determines a mode used by the multi-mode source encoder to source code a given frame or other designated portion of the information, and channel codes the source-coded portion of the information utilizing an error protection profile identified at least in part based on the determined mode. A multi-mode channel decoder is operative to hypothesize that a particular one of the modes of the multi-mode source encoder was used to source code the designated portion of the information.

Abstract: In a communications system implementing an in-band on channel AM (IBOC-AM) (also known as “hybrid IBOC-AM”) scheme, digitally modulated signals are transmitted in a 30 kHz digital band centered at an analog host AM carrier frequency fc. 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 fc. 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 “second adjacent channel interference.” 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.

Abstract: In a communications system implementing, e.g., an in-band on channel AM (IBOC-AM) (also known as “hybrid IBOC-AM”) scheme, multiple bit streams are used to represent an audio signal to be transmitted over one or more frequency bands including, e.g., parts of an AM frequency band for radio broadcast. These bit streams contain various and/or equivalent amounts of audio information. In an illustrative embodiment, at least one of the bit streams is a core bit stream containing core audio information. The remaining bit streams are enhancement bit streams containing enhancement audio information. The core bit stream is necessary for recovering the audio signal with minimal acceptable quality. Such quality is enhanced when the core bit stream, together with one or more of the enhancement bit streams, is used to recover the audio signal. In accordance with the invention, the AM frequency band is divided into subbands.

Abstract: Techniques for processing received information in a communication system, such that performance is significantly improved in the presence of certain types of interference. In an illustrative embodiment, first and second digital sidebands are transmitted on either side of an FM or AM host carrier signal in a hybrid in-band on-channel (HIBOC) digital audio broadcasting (DAB) system. The compressed digital audio information in the sidebands is encoded using an outer code, e.g., a cyclic redundancy code (CRC), and an inner code, e.g., a complementary punctured pair convolutional (CPPC) code. A receiver generates an error indicator based at least in part on a first decoding of the received information. The error indicator characterizes interference associated with at least one of the digital sidebands. The receiver then generates at least one alternative decoding of the received information if the error indicator has a designated characteristic.

Abstract: Methods and apparatus for decoding multiple program information, e.g., audio, video or image information, in a communication system are disclosed. In an illustrative embodiment, a multiple program decoder includes a deinterleaver for deinterleaving information corresponding to a set of frames, using a specified deinterleaving length. A given one of the frames includes information from each of at least a subset of the programs, and the frames are encoded using an outer code, e.g., a CRC code, RS code, BCH code or other type of linear block code, and an inner code, e.g., a convolutional code, turbo code or trellis coded modulation. The multiple program decoder includes an inner code decoder for decoding the inner code over one or more of the programs, and an outer code decoder for decoding the outer code for a selected one of the programs.

Abstract: In a communications system implementing an in-band on channel AM (IBOC-AM) (also known as “hybrid IBOC-AM”) scheme, digitally modulated signals are transmitted in a 30 kHz digital band centered at an analog host AM carrier frequency fc. 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 fc. 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 “second adjacent channel interference.” 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.

Abstract: Methods and apparatus for processing information, e.g., audio, video or image information, for transmission in a communication system are disclosed. In an illustrative embodiment, a multiple program coder encodes a bitstream for each of the programs, in accordance with a specified bit allocation. An outer code encoder receives the encoded bitstreams from the multiple program coder, and jointly applies an outer code, e.g., a CRC code, RS code, BCH code or other type of linear block code, to subblocks of a subset of the resulting encoded bitstreams. The outer code is applied such that subblocks of each of the encoded bitstreams in the subset of the encoded bitstrcams are associated with a single outer code block. The number of subblocks associated with a given outer code block may be an integer or non-integer number of code blocks.