Patent application number | Description | Published |
20080260073 | Ecoding and decoding methods and apparatus for use in a wireless communication system - The claimed subject matter relates to encoding and decoding information in a wireless communication system using soft-demodulation and interleaving of concatenated code received in a strip channel. A set of symbols is received containing a plurality of information bits, dividing the received set of symbols into a plurality of subsets of symbols, each subset corresponding to the input of an inner code demodulation selecting a set of initial a priori values of the inner code demodulation for each subset of symbols, and demodulating each subset of symbols, using the initial a priori values of the subset of symbols and an inner code generator matrix, to generate a plurality of first soft information values as the output of the inner code demodulation. Each of the first soft information values is associated to one of the plurality of information bits using an outer code generator matrix, calculating a plurality of second soft information values as the output of the outer code demodulation, wherein each second soft information value corresponds to one of the information bits and is calculated using at least two of the first soft information values associated with the information bit, determining a new set of a priori values of the inner code demodulation for each subset of symbols, using the second soft information values and the outer code generator matrix, and replacing the initial a priori values with the new a priori values, and repeating the demodulating, associating, calculating and determining actions at least once. | 10-23-2008 |
20090059841 | Wireless communication methods and apparatus using beacon signals - Methods and apparatus supporting peer to peer communications are discussed. A base station, serving as an access node for wireless terminals also communicates information supporting peer to peer communications. A base station transmits a beacon signal conveying information about a peer to peer frequency band and also receives user data from a plurality of wireless terminals, using the base station as a current point of network attachment. In some embodiments, the beacon signal is transmitted into the same frequency band being used for access node based communications and identifies a different frequency band which is to be used as a peer to peer frequency band. Alternatively, or in addition, in support of peer to peer communications, a beacon signal transmission apparatus, a free standing device which doesn't transmit user data, transmits a sequence of beacon signal bursts, each beacon signal burst including at least one high power beacon symbol. | 03-05-2009 |
20090063925 | LCPC DECODING METHODS AND APPARATUS - A flexible and relatively hardware efficient LDPC decoder is described. The decoder can be implemented with a level of parallelism which is less than the full parallelism of the code structure used to control the decoding process. Each command of a relatively simple control code used to describe the code structure can be stored and executed multiple times to complete the decoding of a codeword. Different codeword lengths are supported using the same set of control code instructions but with the code being implemented a different number of times depending on the codeword length. The decoder can switch between decoding codewords of different lengths, without the need to change the stored code description information, by simply changing a code lifting factor that is indicative of codeword length and is used to control the decoding process. When decoding codewords shorter than the maximum supported codeword length some block storage locations may go unused. | 03-05-2009 |
20090063933 | LCPC DECODING METHODS AND APPARATUS - A flexible and relatively hardware efficient LDPC decoder is described. The decoder can be implemented with a level of parallelism which is less than the full parallelism of the code structure used to control the decoding process. Each command of a relatively simple control code used to describe the code structure can be stored and executed multiple times to complete the decoding of a codeword. Different codeword lengths are supported using the same set of control code instructions but with the code being implemented a different number of times depending on the codeword length. The decoder can switch between decoding codewords of different lengths, without the need to change the stored code description information, by simply changing a code lifting factor that is indicative of codeword length and is used to control the decoding process. When decoding codewords shorter than the maximum supported codeword length some block storage locations may go unused. | 03-05-2009 |
20090177869 | EFFICIENT CHECK NODE MESSAGE TRANSFORM APPROXIMATION FOR LDPC DECODER - In modern iterative coding systems such as LDPC decoder and turbo-convolutional decoder in which the invention may be used, the core computations can often be reduced to a sequence of additions and subtractions alternating between logarithm and linear domains A computationally efficient and robust approximation method for log and exp functions is described which involves using a simple bit mapping between fixed point fractional data format and floating point format. The method avoids costly lookup tables and complex computations and further reduces the core processing to a sequence of additions and subtractions using alternating fixed point and floating point processing units. The method is well suited for use in highly optimized hardware implementations which can take advantage of modern advances in standard floating point arithmetic circuit design as well as for software implementation on a wide class of processors equipped with FPU where the invention avoids the need for a typical multi-cycle series of log/exp instructions and especially on a SIMD FPU-equipped processors where log/exp functions are typically scalar. | 07-09-2009 |
20100153812 | METHODS AND APPARATUS FOR ENCODING LDPC CODES - Methods and apparatus for encoding codewords which are particularly well suited for use with low density parity check (LDPC) codes and long codewords are described. The described methods allow encoding graph structures which are largely comprised of multiple identical copies of a much smaller graph. Copies of the smaller graph are subject to a controlled permutation operation to create the larger graph structure. The same controlled permutations are directly implemented to support bit passing between the replicated copies of the small graph. Bits corresponding to individual copies of the graph are stored in a memory and accessed in sets, one from each copy of the graph, using a SIMD read or write instruction. The graph permutation operation may be implemented by simply reordering bits, e.g., using a cyclic permutation operation, in each set of bits read out of a bit memory so that the bits are passed to processing circuits corresponding to different copies of the small graph. | 06-17-2010 |
20100278034 | Efficient signal transmission methods and apparatus using a shared transmission resource - A device includes a zero symbol rate (ZSR) coding/modulation module and a second type coding/modulation module. Both modules generate modulation symbols to be conveyed using the same air link resources but with the non-zero ZSR symbols having a higher power level. The ZSR module generates a mixture of zero and non-zero modulation symbols. A ZSR modulation scheme communicates information using both the position of the non-zero modulation symbols and the phase and/or amplitude of the non-zero modulation symbols. Different ZSR schemes, implementing different ratios relating the number of zero symbols to the total number of symbols, can be associated with different low data rates while second module modulation schemes can be associated with different high data rates. Modulation symbols from two modules are in some embodiments, superimposed. In some embodiments, non-zero ZSR modulation symbols punch out second module modulation symbols which occupy the same air link resource. | 11-04-2010 |
20120269282 | ENCODING AND DECODING METHODS AND APPARATUS FOR USE IN A WIRELESS COMMUNICATION SYSTEM - The claimed subject matter relates to encoding and decoding information in a wireless communication system using soft-demodulation and interleaving of concatenated code received in a strip channel. A set of symbols is received containing a plurality of information bits, dividing the received set of symbols into a plurality of subsets of symbols, each subset corresponding to the input of an inner code demodulation selecting a set of initial a priori values of the inner code demodulation for each subset of symbols, and demodulating each subset of symbols, using the initial a priori values of the subset of symbols and an inner code generator matrix, to generate a plurality of first soft information values as the output of the inner code demodulation. | 10-25-2012 |