Abstract: Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages. These performance advantages allow a noise margin target to be achieved using simpler component codes and a much shorter interleaver than was needed when using prior art codes such as Turbo codes. Decoders are also provided. Both encoding and decoding complexity can be lowered, and interleavers can be made much shorter, thereby shortening the block lengths needed in receiver elements such as equalizers and other decision-directed loops.

Abstract: Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages.

Abstract: Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages. These performance advantages allow a noise margin target to be achieved using simpler component codes and a much shorter interleaver than was needed when using prior art codes such as Turbo codes. Decoders are also provided. Both encoding and decoding complexity can be lowered, and interleavers can be made much shorter, thereby shortening the block lengths needed in receiver elements such as equalizers and other decision-directed loops.

Abstract: Serially-concatenated codes are formed in accordance with the present invention using a constrained interleaver. The constrained interleaver cause the minimum distance of the serial concatenated code to increase above the minimum distance of the inner code alone by adding a constraint that forces some or all of the distance of the outer code onto the serially-concatenated code. This allows the serially-concatenated code to be jointly optimized in terms of both minimum distance and error coefficient to provide significant performance advantages.

Abstract: Two decoding algorithms are introduced for the decoding of multi-level coded modulation and other types of coded modulation involving component codes and interleaving operations. An improved hard iterative decoding (IHID) algorithm is presented that improves upon a hard iteration decoding technique by adding a stopping criterion. Also, a list Viterbi hard iteration decoding (LV-IHID) algorithm is presented that employs list decoding in conjunction with the IHID algorithm. Both of these decoding algorithms improve upon conventional multi-stage decoding by reducing the effective error multiplicity that is observed at the lowest coding level. It is demonstrated that the LV-IHID algorithm performs close to soft iterative decoding. The computational and delay complexity of the proposed decoding algorithms compare favorably with soft iterative decoding strategies. Also, a novel labeling strategy for MLC design is presented.

Abstract: A quadrature-multiplexed continuous phase modulation (QM-CPM) signal is made up of the real parts of two underlying CPM signals whose information content can be recovered from just their real parts. The real parts of two such signals are I/Q multiplexed and transmitted onto a single channel to approximately double the bits/Hz of the underlying CPM signals, while maintaining the same or similar minimum distance. A class of QM-CPFSK (QM-continuous phase frequency shift keyed) signals are presented that use binary signaling but more phase states, and M2-ary QM-CPFSK signals are derived from constant envelope M-ary CPFSK signals. M2-ary multi-amplitude CPFSK signaling schemes are constructed that maintain the same distance as known multi-amplitude CPFSK schemes, but more than double the bandwidth efficiency in bits/Hz. In addition to these CPFSK based embodiments, embodiments are provided that more generally use CPM, non-continuous phase modulated signals, and even trellis-based PAM based signals.

Abstract: The present invention centers upon uplink communication protocols for use primarily with orthogonal frequency division multiple access (OFDMA) communication systems. Aspects of the invention relate to narrow band frequency division multiplexed (NBFDM) modulation protocols primarily for uplink usage in asymmetric OFDMA communication systems. In particular, NBFDM uplinks that use quadrature multiplexed continuous phase modulation are detailed and noncoherent detection schemes are developed to process the uplink channel signals without the need to transmit uplink phase reference signals. Other aspects of the invention relate to burst mode uplink communications in OFDMA systems such as those involving opportunistic beamforming.

Abstract: A class of bandwidth reduction techniques are used develop a broad class of modulation types collectively called SSB-FM. These signals can be used to construct communication systems that provide bandwidth-normalized performance gains of 10 dB or more when compared to popular prior art modulation methods. An aspect of the invention involves mapping trellis paths in a complex signal space onto corresponding real-valued trellis signals with desirable spectral properties. The invention can be used map continuous phase modulated (CPM) signals onto simpler amplitude-modulated trellis signals having double the channel capacity of prior art CPM signals. Multi-amplitude signaling and frequency division multiplexing may also be incorporated to further accommodate more information per symbol.