Abstract: Mud pulse telemetry systems and methods may employ a downhole pulser to encode a digital telemetry data stream as pressure fluctuations in a fluid flow stream. An arrangement of spatially separated sensors acquire pressure-responsive measurements at multiple positions within the plumbing of a drill rig. A receiver collects and digitizes the measurements from the spatially separated sensors and subjects them to a principal components analysis (PCA) to determine those one or more basis vectors associated the telemetry signal. The PCA process may employ decomposition of a spatial correlation/covariance matrix or a temporal-spatial correlation/covariance tensor. The selected basis vector(s) are then used to obtain the telemetry signal for demodulation into the telemetry data stream.

Abstract: Mud pulse telemetry systems and methods may employ a downhole pulser to encode a digital telemetry data stream as pressure fluctuations in a fluid flow stream. An arrangement of spatially separated sensors acquire pressure-responsive measurements at multiple positions within the plumbing of a drill rig. A receiver collects and digitizes the measurements from the spatially separated sensors and subjects them to a principal components analysis (PCA) to determine those one or more basis vectors associated the telemetry signal. The PCA process may employ decomposition of a spatial correlation/covariance matrix or a temporal-spatial correlation/ covariance tensor. The selected basis vector(s) are then used to obtain the telemetry signal for demodulation into the telemetry data stream.

Abstract: A multiple-access communications downlink uses OFDM and error-correcting codes to send data to multiple terminals from a single access point, in which packets of message information for multiple users are aggregated and encoded into a single error-correction codeword, in which assigned time slots corresponding to specific OFDM symbols are used to separate different users, so that a near-capacity achieving channel coding system constructs a single codeword for use with iterative decoding architectures at the mobile terminals.

Abstract: In one aspect thereof this invention provides a method to increase data throughput in an Orthogonal Frequency Division Multiplex (OFDM) wireless communications system. The method includes modeling data throughput as a function of received Signal to Noise Ratio (SNR) with a sigmoid function to produce a throughput curve characterized as having a lower knee region and an upper knee region; and performing a gradient ascent search along the throughput curve by varying the power of a plurality of sub-carriers so as to remove power from any sub-carrier having a received SNR to the left of the lower knee region, and to re-allocate the removed power to sub-carriers having a received SNR to the right of the lower knee region.

Abstract: Puncture sequences S1, S2, etc. for code rates R1, R2, etc. less than a maximum code rate Rmax are defined subsets of a maximum rate puncture sequence Smax that corresponds to the maximum code rate Rmax. Each puncture sequence Si for a code rate Ri is related to the puncture sequence Si?1, of the previous code rate Ri?1, and preferably S1?S2? . . . ?Smax?1?Smax. The puncture sequences are groups of one or more memory elements, each of which is a variable degree, a variable node location, a check degree, or a check node location. A method for deriving such a puncture sequence for variable code rates is also disclosed.

Abstract: In a multi-user frequency domain spreading downlink MC-CDMA system, a group of sub-carriers can be replaced by an equivalent sub-carrier of a conventional OFDM modem for purposes of resource allocation to improve the system performance. The chips for a given user are spread only within the group. Confinement insures synchronization between different users' chips that is essential to the recovering and separation of user symbols at the receiver. There is no limit imposed on the group size, which permits different spreading code lengths to be used for different scenarios or for performance tuning.

Abstract: Disclosed is an OFDM communications system and a method of operating the OFDM communications system. The system includes an OFDM transmitter for transmitting data over a plurality of OFDM sub-channels, where the OFDM transmitter has a plurality of modulators of different types. The system further includes an OFDM receiver for receiving the data from the plurality of OFDM sub-channels, where the OFDM receiver has a plurality of corresponding demodulators of the different types. The system further includes, in accordance with this invention, an adaptive learning automata that contains a group or team of independent, decentralized automaton operating in accordance with a game theory-based approach. Each of the plurality of automaton are responsible for managing one MCS switching threshold value so as to maximize at least one selected performance criterion.

Abstract: Puncture sequences S1, S2, etc. for code rates R1, R2, etc. less than a maximum code rate Rmax are defined subsets of a maximum rate puncture sequence Smax that corresponds to the maximum code rate Rmax. Each puncture sequence Si for a code rate Ri is related to the puncture sequence Si-1, of the previous code rate Ri-1, and preferably S1⊂S2⊂ . . . ⊂Smax-1⊂Smax. The puncture sequences are groups of one or more memory elements, each of which is a variable degree, a variable node location, a check degree, or a check node location. A method for deriving such a puncture sequence for variable code rates is also disclosed.