Abstract: Estimation of channel characteristics and interference level in a time-varying multi-carrier multi-user systems is carried out concurrently. To perform the estimation, a multitude of data symbols and dedicated pilot symbols are transmitted over the channel. The estimate of the interference level is used to estimate the channel parameters.

Abstract: Methods and apparatus for reverse link timing correction in a wireless communication device. In particular, when a handoff of the device from a first sector currently serving the device to a second sector not currently serving the device is detected, a first function linking timing correction of a reverse link of the device to forward link timing corrections is changed to a second function for timing correction. In particular, the second function is configured to correct reverse link timing during a time period of either during or for a predetermined period after a handoff of the device from the first sector to the second sector, where the second function is based on a criterion different from criteria of the first function.

Abstract: A channel estimation system comprises a filtering component that selectively scales a plurality of carriers as a function of location of the plurality of carriers within a frequency band, wherein the plurality of carriers comprises at least one data carrier and at least one pilot carrier. A component thereafter extrapolates an observation from the at least one pilot carrier, wherein a channel is estimated as a function of the extrapolated observation. The scaling of the carriers facilitates reducing a flooring effect associated with channel estimation. The filtering component can be employed at a transmitter and/or at a receiver, and can be activated and/or deactivated as a function of a sensed data packet type.

Abstract: Transmission patterns for pilot symbols transmitted from a mobile station or base station are provided. The pattern allows for improved receipt of the pilot symbols transmitted. In addition, schemes for improving the ability to multiplex pilot symbols without interference and/or biasing from different mobile stations over the same frequencies and in the same time slots.

Abstract: Systems and methodologies are described that facilitate equalization of received signals in a wireless communication environment. Using multiple transmit and/or receive antennas and MIMO technology, multiple data streams can be transmitted within a single tone. During equalization, receivers can separate data received within a tone into individual data streams. The equalization process generally is computationally expensive. Equalizer functions include the inverse operation, which can be computed using the fast square root method; however, the fast square root method involves large numbers of computations for a set of matrices, where the size of a matrix in the set of matrices increases with the number of transmit or receive antennas. Utilizing a modification of the fast square root method, a subset of the elements of the matrices can be selected and updated to reduce the number and/or complexity of computations.

Abstract: Aspects describe controlling a power level for an access terminal in a wireless communication system that utilizes multiple modulation waveforms. The power can be controlled after an Access Grant is received in response to an Access Probe until the mobile device transitions into a steady state. A reference power can be continuously monitored and a setting of a power amplifier can be modified only when the reference power changes. A digital gain of a reverse data channel can be adjusted relative to the reference power level.

Abstract: At a mobile device, a total received power represents signals received from all access points. In order to calculate an appropriate transmit power for communication with a single access point, a mobile device determines a per sector received power level. The mobile device can ascertain a time-domain channel response from each access point pilot signal, ascertain a received digital power lever per sector from each access point pilot signal and, based in part on the digital power level, calculate a received power level from each access point. A per sector received power level can be utilized to conserve battery power and/or to reduce interference in a wireless communications network.

Abstract: Systems and methodologies are described that facilitate mitigation of interference through uplink scheduling in a wireless communication environment. Access points can assign multiple terminals to a single tile or segment of shared resource (e.g., a time frequency region) to maximize the number of terminals supported. However, combinations of certain types of terminals can cause a significant increase in interference. In particular, allocating multiple terminals having a relatively high velocity (e.g., terminals located in moving vehicles) to a single tile can cause an unacceptable increase in interference. To mitigate interference, high velocity terminals can be identified. Once identified, terminals can be allocated to the available tiles based at least in part upon avoiding combinations that result in a significant increase in interference.

Abstract: Each transmitter is assigned a time-only pilot code, a frequency-only pilot code, or a time-frequency pilot code to use for pilot transmission. The pilot codes may be pseudo-random, orthogonal, and/or cyclic-shift codes. To obtain a channel estimate for a transmitter using a time-frequency pilot code composed of a time-only code and a frequency-only code, a receiver multiplies a set of received symbols for each symbol period with a set of code values for the frequency-only code to obtain a set of detected symbols and performs an IDFT on the set of detected symbols to obtain an initial impulse response estimate. The receiver performs code matching on multiple initial impulse response estimates derived for multiple symbol periods with the time-only code to obtain a final impulse response estimate for the desired transmitter. The receiver retains the first L channel taps and zeroes out remaining channel taps, where L is the expected channel length.

Abstract: A method of user power offset estimation for a wireless communication system is disclosed. Dedicated pilot symbols transmitted over at least one time-frequency region for a user are received. Power offset of the user is estimated based on the received dedicated pilot symbols.

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, the number of pilot subbands is greater than the cyclic prefix length. This “oversampling” may be achieved by using more pilot subbands in each symbol period or different sets of pilot subbands in different symbol periods. In one example, a first set of pilot subands may be received in a first symbol period, and a second set of pilot subands may be received in a second symbol period. The first set of pilot subands and the second set of pilot subbands may be staggered in frequency.

Abstract: Each transmitter is assigned a time-only pilot code, a frequency-only pilot code, or a time-frequency pilot code to use for pilot transmission. The pilot codes may be pseudo-random, orthogonal, and/or cyclic-shift codes. To obtain a channel estimate for a transmitter using a time-frequency pilot code composed of a time-only code and a frequency-only code, a receiver multiplies a set of received symbols for each symbol period with a set of code values for the frequency-only code to obtain a set of detected symbols and performs an IDFT on the set of detected symbols to obtain an initial impulse response estimate. The receiver performs code matching on multiple initial impulse response estimates derived for multiple symbol periods with the time-only code to obtain a final impulse response estimate for the desired transmitter. The receiver retains the first L channel taps and zeroes out remaining channel taps, where L is the expected channel length.

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, the number of pilot subbands is greater than the cyclic prefix length. This “oversampling” may be achieved by using more pilot subbands in each symbol period or different sets of pilot subbands in different symbol periods. In one channel estimation technique, first and second groups of received pilot symbols are obtained for first and second pilot subband sets, respectively, and used to derive first and second frequency response estimates, respectively. First and second impulse response estimates are derived based on the first and second frequency response estimates, respectively, and used to derive a third impulse response estimate having more taps than the number of pilot subbands in either set.

Abstract: Efficient pilot transmission schemes for multi-antenna communication systems are described. In general, MISO receivers prefer a pilot transmitted in one spatial direction, and MIMO receivers typically require a pilot transmitted in different spatial directions. In one pilot transmission scheme, a first set of T scaled pilot symbols is generated with a first training vector and transmitted (e.g., continuously) from T transmit antennas, where T>1. If MIMO receiver(s) are to be supported by the system, then at least T?1 additional sets of T scaled pilot symbols are generated with at least T?1 additional training vectors and transmitted from the T transmit antennas. The training vectors are for different (e.g., orthogonal) spatial directions. Each MISO receiver can estimate its MISO channel based on the first set of scaled pilot symbols. Each MIMO receiver can estimate its MIMO channel based on the first and additional sets of scaled pilot symbols.