Agere Systems Inc.

Agere Systems Guardian Corp.

Lucent Technologies Inc.

Mosaid Technologies Corporation

Jerry Nicholas Laneman

Carl-Erik Wilhelm Sundberg

Deepen Sinha

James Walter Tracey

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. If the interference is not detected, the receiver utilizes the designated portion of the sideband in the decoding process by using a hard-decision decoding (HDD) technique. Advantageously, this multi-mode approach of the present invention provides significantly reduced complexity relative to conventional maximum likelihood decoding, and also provides a block error flag for use in error concealment in an audio decoder. In addition, the invention provides improved performance relative to conventional systems in terms of reducing the probability that a block error flag will be generated, while also providing a manageable probability of undetected errors.

Multi-mode decoding for digital audio broadcasting and other applications

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. The invention is particularly well-suited for use in the processing of encoded digital audio information received in a hybrid in-band on-channel (HIBOC) digital audio broadcasting (DAB) system, but is also applicable to other types of information and other types of communication systems.

Error screening based on code and control information consistency in a communication system

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. The invention is particularly well-suited for use in the transmission of digital audio information in a hybrid in-band on-channel (HIBOC) digital audio broadcasting (DAB) system, but is also applicable to other types of communication systems.

Channel code configurations for digital audio broadcasting systems and other types of communication systems

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. For example, the receiver may generate the alternative decoding by eliminating from consideration in the receiver decoding process a designated portion of at least one of the digital sidebands. The error indicator may be indicative of the presence or absence of a first adjacent interference signal of a particular level within a frequency band associated with one of the sidebands, and may be based on, e.g., a signal-to-noise ratio measurement generated from a pilot tone associated with a given sideband, and/or an error flag generated using the CRC outer code. Portions of the given sideband may be eliminated from consideration via successive erasures of sideband components, i.e., subbands, thereby resulting in an increase in the effective code rate of the inner code.

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Cambridge, MA, United States of America

Jerry Nicholas Laneman