Abstract: A method of communications channel coding gain optimization using combined ISI cancellation and turbo decoding is provided. Log-likelihood ratio probabilities with extrinsic values are computed from previous iterations of turbo decoding and used to compute the soft-decision values of channel symbols. The soft-decision values are then used to perform intersymbol interference cancellation and generate refined channel log-likelihood ratio probabilities for the next iteration of turbo decoding.

Abstract: In wireless communications, it is necessary to monitor the transmission quality of communications channels to maintain system performance and operation. The invention provides a way of measuring bit error rates in channels at the receiver, without diminishing channel throughput by inserting quality monitoring data into the signal at the transmitter.

Abstract: Conserving power for coded transmissions comprises ceasing to process parity packets once associated data packets are deemed correct or corrected. Once data packets are deemed correct or corrected, the receiving unit can shut off during the transmission of parity packets.

Abstract: A system and method are provided for generating bit log likelihood ratio (LLR) values for two-layered Quadrature Phase-Shift Keying (QPSK) turbo decoding in a wireless communications user terminal (UT). The method includes receiving a two-layered QPSK signal with an energy ratio that is unknown, but typically defined as either k12 or k22. The method selects a mismatched energy ratio (k2) between k12 and k22, and generating bit LLR values for two-layered QPSK turbo decoding, using the mismatched k2 energy ratio. For example, if the received two-layered QPSK signal is known to have an energy ratio of about 4 or about 6.25. Then, k2 is selected to be about 5.0625. Alternately stated, the mismatched k2 energy ratio in selected by determining the approximate midpoint between k12 and k22.

Abstract: According to one aspect of the invention, a method for determining a power control set point is provided. In one embodiment, the power control set point is determined based on one or more factors including a first factor corresponding to a pilot bit error rate, a second factor corresponding to a normalized signal variance, and a third factor corresponding to an average number of fingers in lock.

Abstract: A novel and improved method and apparatus for performing closed loop forward link power control using a selected dedicated and power controlled forward link signal is described. A “Selected Signal Bit Error Rate” (SSBER) is estimated, where each selected signal “bit” consists of a number selected signal chips distributed over a frame. In addition, the method estimates the normalized variance of the signal energy (or C/I) for each packet. The average number of fingers in lock is also used to determine the power control set point.

Abstract: A system and method for modulation diversity uses interleaving. Code bits are placed into groups and are then shuffled within each group.

Abstract: A system and method for frequency diversity uses interleaving. Subcarriers of an interlace are interleaved in a bit reversal fashion and the interlaces are interleaved in the bit reversal fashion.

Abstract: A receive filter receives signals from a communication channel. The received signals correspond to original Walsh covered chip sequences transmitted by a transmit filter through the communication channel to the receive filter. The received signals are processed by an equalizer to generate a soft estimate of chip sequences corresponding to the original Walsh covered chip sequences. An N chip Walsh decover is then utilized to generate a soft estimate of code symbols corresponding to the soft estimate of the chip sequences. A number of symbol slicers are then used in parallel to produce a hard estimate of the code symbols corresponding to the soft estimate of code symbols generated by the N chip Walsh decover. Thereafter an N chip Walsh cover is used as part of a scheme to generate a hard estimate of chip sequences corresponding to the hard estimate of the code symbols generated by the symbol slicers.

Abstract: Techniques for transmitting data from a transmitter unit to a receiver unit in a multiple-input multiple-output (MIMO) communication system. In one method, at the receiver unit, a number of signals are received via a number of receive antennas, with the received signal from each receive antenna comprising a combination of one or more signals transmitted from the transmitter unit. The received signals are processed with a spatial, a space-time, or a full-CSI technique to derive channel state information (CSI) indicative of the characteristics of a number of transmission channels used for data transmission. The CSI (which may comprise SNR estimates, data rate indicators, complex channel gains, or some other information) is transmitted back to the transmitter unit. At the transmitter unit, the CSI is received and data for transmission to the receiver unit is processed (e.g., coded and modulated) based on the received CSI.

Abstract: In wireless communications, it is necessary to monitor the transmission quality of communications channels to maintain system performance and operation. The invention provides a way of measuring bit error rates in channels at the receiver, without diminishing channel throughput by inserting quality monitoring data into the signal at the transmitter.

Abstract: Coding techniques for a (e.g., OFDM) communication system capable of transmitting data on a number of “transmission channels” at different information bit rates based on the channels' achieved SNR. A base code is used in combination with common or variable puncturing to achieve different coding rates required by the transmission channels. The data (i.e., information bits) for a data transmission is encoded with the base code, and the coded bits for each channel (or group of channels with the similar transmission capabilities) are punctured to achieve the required coding rate. The coded bits may be interleaved (e.g., to combat fading and remove correlation between coded bits in each modulation symbol) prior to puncturing. The unpunctured coded bits are grouped into non-binary symbols and mapped to modulation symbols (e.g., using Gray mapping). The modulation symbol may be “pre-conditioned” and prior to transmission.

Abstract: An efficient telecommunications receiver system for accurately decoding a received composite signal having a data signal component and a pilot signal component includes a first circuit for receiving the composite signal and extracting a pilot signal and a data signal from received composite signal. A second circuit calculates a log-likelihood ratio as a function of a channel estimate based on the pilot signal. A third circuit scales the log-likelihood ratio by a predetermined log-likelihood ratio scaling factor and provides an accurate log-likelihood value in response thereto. A fourth circuit decodes the received composite signal based on the accurate log-likelihood value and the data signal. The third circuit includes a carrier signal-to-interference ratio circuit for computing a first signal-to-interference ratio and a second signal-to-interference ratio based partly on the pilot signal.

Abstract: In wireless communications, it is necessary to monitor the transmission quality of communications channels to maintain system performance and operation. The invention provides a way of measuring bit error rates in channels at the receiver, without diminishing channel throughput by inserting quality monitoring data into the signal at the transmitter.

Abstract: Coding techniques for a (e.g., OFDM) communication system capable of transmitting data on a number of “transmission channels” at different information bit rates based on the channels' achieved SNR. A base code is used in combination with common or variable puncturing to achieve different coding rates required by the transmission channels. The data (i.e., information bits) for a data transmission is encoded with the base code, and the coded bits for each channel (or group of channels with the similar transmission capabilities) are punctured to achieve the required coding rate. The coded bits may be interleaved (e.g., to combat fading and remove correlation between coded bits in each modulation symbol) prior to puncturing. The unpunctured coded bits are grouped into non-binary symbols and mapped to modulation symbols (e.g., using Gray mapping). The modulation symbol may be “pre-conditioned” and prior to transmission.

Abstract: A power control system for controlling the transmission power in a system wherein the transmission power may be gated or capped. The receiver employs a combination of closed loop and outer loop power control. The outer loop is frozen upon detection by the receiver that the signal has been capped or gated.

Abstract: For an iterative channel and interference estimation and decoding scheme, prior information for channel gain and interference is initially obtained based on received pilot symbols. Forward information for code bits corresponding to received data symbols is derived based on the received data symbols and the prior information and then decoded to obtain feedback information for the code bits corresponding to the received data symbols. A posteriori information for channel gain and interference for each received data symbol is derived based on the feedback information for that received data symbol. The a posteriori information for the received data symbols and the prior information are combined to obtain updated information for channel gain and interference for each received data symbol. The process can be repeated for any number of iterations. The prior, a posteriori, and updated information may be represented by joint probability distributions on channel gain and interference.

Abstract: The disclosed embodiments provide for methods and systems for initial frequency acquisition in a wireless communication network. In one aspect, a method for initial frequency acquisition includes the acts of receiving a stream of input samples from a transmitter, determining an estimate for a frequency offset associated with the transmitter and the receiver based on the received input samples, and compensating for the frequency offset to achieve an initial frequency acquisition.

Abstract: Pilot transmission and channel estimation techniques for an OFDM system with excess delay spread are described. To mitigate the deleterious effects of excess delay spread, time filtering is utilized. Time filtering is utilized to combat excess delay spread effects in channel estimation. The time filtering is performed in the presence of staggered pilots and helps in improving the channel estimate in the presence of excess delay spread.

Abstract: To broadcast different types of transmission having different tiers of coverage in a wireless broadcast network, each base station processes data for a wide-area transmission in accordance with a first mode (or coding and modulation scheme) to generate data symbols for the wide-area transmission and processes data for a local transmission in accordance with a second mode to generate data symbols for the local transmission. The first and second modes are selected based on the desired coverage for wide-area and local transmissions, respectively. The base station also generates pilots and overhead information for local and wide-area transmissions. The data, pilots, and overhead information for local and wide-area transmissions are multiplexed onto their transmission spans, which may be different sets of frequency subbands, different time segments, or different groups of subbands in different time segments. More than two different types of transmission may also be multiplexed and broadcast.