摘要:
Embodiments include a method of signal processing in which each of a set of individual estimates of a transmitted symbol is added to a combined symbol estimate based on a relation between a signal quality value corresponding to the individual estimate and a threshold value, where the threshold value is based on a maximum among the signal quality values.
摘要:
Techniques for controlling operation of control loops in a receiver are described. The operation of at least one control loop is modified in conjunction with a change in operating state, which may correspond to a change in linearity state, gain state, operating frequency, antenna configuration, etc. A change in linearity state may occur when jammers are detected and may cause bias current of analog circuit blocks to be adjusted. The at least one control loop to be modified may include a DC loop, an AGC loop, etc. The operation of a control loop may be modified by disabling the control loop or changing its time constant prior to changing operating state, waiting a predetermined amount of time to allow the receiver to settle, and enabling the control loop or restoring its time constant after waiting the predetermined amount of time.
摘要:
Huffman trees may be rapidly and effectively created by sorting a plurality of nodes by weight in an insertion sorter stack, popping the two lowest weighted nodes from the insertion sorter stack, forming a branch node from the popped entries, and placing the branch node into the insertion sorter.
摘要:
A technique for noise reduction in a wireless communication system uses controllable bandwidth filters (120) to filter a received signal. In a typical implementation, the filters (120) are used at baseband frequencies. A measurement (RSSI) is indicative of the strength of the received signal. A control circuit (144) generates a control signal (146) to control the bandwidth of the filters (120). If the received signal strength is above a first threshold, a wider bandwidth may be used for the filters (120). If the received signal is below a second threshold, the control circuit (144) generates the control signal (146) to set the filters (120) to a more narrow bandwidth. The system (100) may also be used with digital filters (150, 152) following digitization by analog to digital converters (ADCs) (130, 132). The system (100) is particularly well-suited for operation with noise-shaped ADCs (130, 132), such as Delta-Sigma converters.
摘要:
The current invention involves a forward error detection system, especially for use with Low Density Parity Check codes. A parallel SISO structure allows the decoder to process multiple parity equations at the same time. There is a new SISO decoder which allows for the updating of the Log-likelihood-ratio's in a single operation, as opposed to the two pass traditionally associated with the Tanner Graph's. In the decoder, there is a mapping structure that correctly aligns the stored estimates, the stored differences and the SISO's. There is also the ability to deal with multiple instances of the same data being processed at the same time. This structure manages the updates and the differences in such a manner that all calculations on a single piece of data that are processed in parallel are incorporated correctly in the new updated estimates.
摘要:
A transmitter generates a pair of test weight vectors, each vector comprised of a plurality of complex entries, with each entry corresponding a different one of a plurality of antennae. The first and second complex weight vectors are applied to a dedicated pilot signal during alternate time intervals. During each time interval, the average of the first and second complex weight vectors is applied to the data traffic transmitted by the transmitter. A receiver alternately receives the pilot signal as multiplied by the first and second weight vectors as described above. The receiver determines which of the weighted pilot signals resulted in a stronger signal received at the mobile and, based upon this determination, transmits feedback. The transmitter receives the feedback and updates the first and second weights accordingly
摘要:
A single physical channel carries “fast feedback” information in such a way that each type of data is on a physical sub-channel. The sub-channels are not “logical” channels in that they cannot be separated by logical functions alone because some knowledge of the modulation mechanisms is required. Each sub-channel is independently channel coded (this is outer channel coding if an inner code is applied). The resulting code symbols from all sub-channels are then merged into one set of symbols. These code symbols can then optionally be concatenation interleaved and inner channel coded, if the performance enhancement is desired and the complexity is acceptable. The result is then extended by code symbol repetition to provide a total number of symbols greater than or equal to one of the possible quantities of symbols per frame supported by the physical channel, and then decimated (symbols deleted) to provide a number of symbols equal to one of the allowable quantities of symbols per frame. The result is then interleaved, and transmitted over the physical channel.
摘要:
When a mobile communication unit (e.g. a cellular telephone) is powered up, the unit must lock on to a local base station, or "acquire" a base station signal, to enable the user to send and receive calls. To lock on a local base station, the mobile unit must determine the delay at which the base station is sending the pseudo random (PN) code. This process is called the "acquisition." The current art of acquiring a base station involves collecting a set of samples at a particular code phase, or delay, testing the collected sample, and repeating these steps using another code phase until the correct code phase is found. The present invention discloses a method and apparatus for collecting a set of samples at a particular code phase, and simultaneously testing the collected sample and collecting the next set of samples for another code phase. Using multiple banks, the system resources such as the dwell accumulators and the DSP are used concurrently to reduce the time required to test the phase delays of the short code to lock on to a base station.
摘要:
A method and apparatus for decoding of tailbiting convolutional codes (TBCC) are disclosed. The proposed modified maximum-likelihood TBCC decoding technique preserves error correction performance of optimal maximum-likelihood based TBCC decoding, while the computational complexity is substantially decreased since a reduced number of decoding states has been evaluated. Compare to other sub-optimal TBCC decoding algorithms, modified maximum-likelihood TBCC decoding achieves improved packet error rate performance with similar computational complexity.