摘要:
Techniques for performing adaptive channel estimation are described. A receiver derives channel estimates for a wireless channel based on received pilot symbols and at least one estimation parameter. The receiver updates the at least one estimation parameter based on the received pilot symbols. The at least one estimation parameter may be for an innovations representation model of the wireless channel and may be updated based on a cost function with costs defined by prediction errors. In one design, the receiver derives predicted pilot symbols based on the received pilot symbols and the at least one estimation parameter, determines prediction errors based on the received pilot symbols and the predicted pilot symbols, and further derives error gradients based on the prediction errors. The receiver then updates the at least one estimation parameter based on the error gradients and the prediction errors, e.g., if a stability test is satisfied.
摘要:
Schemes to time-align transmissions from multiple base stations to a terminal. To achieve time-alignment, differences between the arrival times of transmissions from the base stations, as observed at the terminal, are determined and provided to the system and used to adjust the timing at the base stations such that terminal-specific radio frames arrive at the terminal within a particular time window. In one scheme, a time difference between two base stations is partitioned into a frame-level time difference and a chip-level time difference. Whenever requested to perform and report time difference measurements, the terminal measures the chip-level timing for each candidate base station relative to a reference base station. Additionally, the terminal also measures the frame-level timing and includes this information in the time difference measurement only if required. Otherwise, the terminal sets the frame-level part to a predetermined value (e.g., zero).
摘要:
Techniques to more efficiently control the transmit power for a data transmission that uses a number of formats (e.g., rates, transport formats). Different formats for a given data channel (e.g., transport channel) may require different target SNIRs to achieved a particular BLER. In one aspect, individual target BLER may be specified for each format of each data channel. In another aspect, various power control schemes are provided to achieve different target SNIRs for different formats. In a first power control scheme, multiple individual outer loops are maintained for multiple formats. For each format, its associated outer loop attempts to set the target SNIR such that the target BLER specified for that format is achieved. In a second power control scheme, multiple individual outer loops are maintained and the base station further applies different adjustments to the transmit power levels for different formats.
摘要:
A rake receiver finger assignor is configured to assign a rake receiver finger to a time offset between identified signal path time offsets in accordance with a concentration of identified signal paths from a transmitter to a rake receiver. In accordance with the exemplary embodiment, a number of identified signal paths having time offsets within a time window are observed to determine the concentration of signal paths identified by a path searcher. If the number of identified signal paths indicates a concentrated distribution of signal paths such as during a fat path condition, at least one rake finger is assigned between at a time offset between two identified signal paths.
摘要:
Quick frequency tracking (QFT), quick time tracking (QTT), and non-causal pilot filtering (NCP) are used to detect sporadically transmitted signaling, e.g., paging indicators. For QFT, multiple hypothesized frequency errors are applied to an input signal to obtain multiple rotated signals. The energies of the rotated signals are computed. The hypothesized frequency error with the largest energy is provided as a frequency error estimate. For QTT, coherent accumulation is performed on the input signal for a first set of time offsets, e.g., early, on-time, and late. Interpolation, energy computation, and non-coherent accumulation are then performed to obtain a timing error estimate with higher time resolution. For NCP, pilot symbols are filtered with a non-causal filter to obtain pilot estimates for one antenna for non-STTD and for two antennas for STTD. The frequency and timing error estimates and the pilot estimates are used to detect the signaling.
摘要:
Techniques for predicting weights used for closed-loop transmit diversity. In a channel prediction scheme, channel gains for multiple transmit antennas are initially estimated (e.g., based on pilots received from these antennas) and used to derive predicted channel gains for a future time instant. The predicted channel gains are then used to derive predicted weights that are deemed to be “optimal” at the future time instant. Optimality may be determined based on one or more criteria, such as maximizing a received SNR for the received signals. In a weight prediction scheme, the channel gains for the multiple antennas are estimated and used to compute optimal weights for the current time instant. The current optimal weights are then used to predict the optimal weights at the future time instant. For both schemes, the prediction may be performed based on an adaptive filter (e.g., LMS or RLS filter) or a non-adaptive filter.
摘要:
Techniques to mitigate spikes in transmit power, by reducing the magnitude and/or duration of the spikes, are described. Initially, power control is performed in a normal manner and in accordance with a transmit power control (TPC) scheme. If a (e.g., upward) transmit power spike is detected, the power control is performed in a manner to mitigate the adverse effects of the spike and in accordance with another TPC scheme. An upward transmit power spike may be detected, e.g., if a predetermined number of consecutive TPC commands in the upward direction is obtained for increasing transmit power. The upward transmit power spike may be mitigated by limiting the transmit power, reducing the rate of transmit power adjustment in the upward direction, delaying and/or filtering TPC decisions used for transmit power adjustment, preventing upward adjustment of transmit power, and so on. Multiple states may be defined and used to facilitate power control with spike mitigation.
摘要:
Techniques are provided to control the transmit power for data transmission on multiple transport channels having different signal quality (SIR) targets. A single SIR target is maintained for all transport channels, and this SIR target is adjusted based only on active transport channels. For each update interval, a data processor processes at least one data block received in the current update interval on at least one of the transport channels and provides the status of each received data block. A controller increases the SIR target based on an up step if any received data block is erased and decreases the SIR target based on a down step if all received data blocks are good. If any received data block is erased, the down step used to adjust the SIR target may be set to the smallest down step size required by all transport channels with erased data blocks.
摘要:
Apparatus and methods for low power sensing of wireless access technologies are disclosed. In particular, a mobile wireless device, such as an access terminal, may utilize a lower power circuitry portion that operates at a lower power than active circuitry, such as a primary transceiver. The lower power circuitry portion includes a configurable searcher that is capable of sensing if signals of one or more various wireless access technologies are present. When the wireless device utilizes sleep or idle modes for power savings, use of the lower power sensing circuitry to sense the presence of wireless access technologies, rather than using an awoken higher power primary transceiver for sensing, affords increased power savings. An added ability of the lower power circuitry to be put into sleep or idles modes achieves even greater power savings.
摘要:
Methods and apparatus are directed to mobile devices utilizing motion and/or position sensors for improving operating performance and/or power efficiency. In one example, a method for reducing power consumption in a mobile device includes receiving movement information, establishing movement data based on the movement information, determining if the mobile device is stationary using the movement data; and reducing the frequency of searching for a base station when the mobile device is stationary. In another example, a mobile device which reduces power consumption based upon movement data includes an RF front end, a receiver coupled to the RF front end, a data demodulator coupled to the receiver, a searcher, coupled to the RF front end and the receiver, which searches for base stations, and a processing unit coupled to the searcher, wherein the processing unit controls the searcher based upon the stationarity of the mobile device.