Abstract: In a multiple-input, multiple-output (MIMO) communication system, a method and apparatus for multi-antenna transmission. In accordance with the preferred embodiment of the present invention a reduced number of transmit weight matrices are fed back to the transmitter. Each transmit weight matrix is then applied to a plurality of subcarriers. Because each transmit weight matrix is applied to more than one subcarrier, the amount of weight matrixs being fed back to the transmitter is greatly reduced.

Abstract: In order to discover neighboring nodes (203, 207, 208) within a particular piconet, a first node (206) determines a list of all nodes (205-207) within its piconet (201) and then transmits to each node within the piconet, a message requiring a response. Depending upon which nodes are heard from, a list is formulated by the first node comprising those nodes neighboring the first node. In order for neighboring nodes within other piconets to “discover” the first node, the first node will also scan its environment to determine piconet identifications for other piconets, and then broadcast a “discovery” message having a piconet identification of a neighboring piconet. In a similar manner, the first node will also scan its environment to determine discovery messages transmitted by other nodes, thus determining neighboring nodes outside its piconet.

Abstract: A signaling system is provided in which a spread spectrum code is cyclically shifted by a cyclical shift dictated by a bit pattern of one or more bits. The cyclically shifted spread spectrum code is used to modulate a carrier frequency, and transmitted from a transmitter to a receiver. At the receiver the signal including the cyclically shifted spectrum code is demodulated to recover the cyclically shifted code. The cyclical shift is then determined and the bit pattern which is associated with the cyclical shift is output. The method can be used in direct sequence spread spectrum communication.

Abstract: A processor includes a first vector processing unit including a first register file and first vector arithmetic logic unit; a second vector processing unit including a second register file and second vector arithmetic logic unit wherein the first register file has a first plurality of cross connections to the second vector arithmetic logic unit; wherein the second register file as a second plurality of cross connections to the first vector arithmetic logic unit.

Abstract: A communication system based upon frequency-domain MIMO processing is disclosed. A transmitting device of the communication system transforms time-domain signals into frequency-domain signals, and weights each frequency-domain signal to form weighted frequency-domain signals with each weighted frequency-domain signal being a function of each frequency-domain signal. The transmitting device transmits weighted time-domain waveforms as a function of the weighted frequency-domain signals. In response thereto, a receiving device of the communication system provides frequency-domain samples that are a function of the one or more weighted time-domain waveforms and weights each frequency-domain sample to form one or more weighted frequency-domain samples with each weighted frequency-domain sample being a function of each frequency-domain sample. The receiving device decodes the weighted frequency-domain sample to obtain the information represented by the time-domain signals.

Abstract: A method includes the steps of receiving (402), by a first receiver (102), a first received signal comprising a first signal (110) and a second signal (120), and receiving (402), by a second receiver (104), a second received signal comprising the first signal (110) and the second signal (120). A branch weight associated with the first receiver (102) and at least one other branch weight associated with the second receiver (104) are determined (406). The branch weight associated with the first receiver (102), the at least one other branch weight associated with the second receiver (102), the first received signal, and the second received signal are combined, forming a combined signal. Channel state information is determined for the combined signal, and the channel state information of the combined signal is restored (412).

Abstract: A method and apparatus for signal combining within a communication system is provided herein. The output of RAKE fingers is combined via a chip combiner. The combined chip stream can be despread with the appropriate Walsh code (defining a particular channel). The resulting symbol stream can then be deinterleaved and decoded.

Abstract: An “identical beacons” field (401) is inserted near the beginning of a transmitted beacon (403) that contains either an integer equal to the number of consecutive identical beacons sent (i.e., identical to the one presently being transmitted) or a repetition bit indicating whether or not the beacon contains changed information when compared to a prior-sent beacon. After sleeping awhile, a node (302-304) wakes up, receives a first portion of the beacon containing the identical beacons field, and analyzes the identical beacons field. Based on the analysis, the node makes a decision on whether to remain “awake” for reception of the remaining beacon or to return to sleep.

Abstract: According to the present invention a received Direct Sequence Code Division Multi-Access (DS-CDMA) signal is differentially decoded at the chip level. A number of signaling schemes can be used in the invention including (1) an ON/OFF signaling scheme in which a pseudo noise number (PN) code is sent only in response to one data bit value, and no signal is sent in response to the other bit value; (2) a Two Code signaling scheme in which bit values of 1 triggers a first PN code to transmitted, and a bit value of 0 triggers a second PN code to be transmitted; and (3) an M-ary signaling method in which a plurality of data bit patterns respectively, trigger a plurality of PN codes to be transmitted. After differential decoding the received signal is despread using one or more PN codes, that can be vector sums of two or more PN codes.

Abstract: When the user is actively transmitting/receiving or has recently transmitted/received on the RF channel, the user is referred to as being in an “active” state. Typically, if the user is in the active state, and neither sends nor receives data for a timer period greater than a threshold, then the user is transitioned off of the RF channel (e.g. transitioned from active to dormant). Once a transition to the dormant state has occurred, the continued transmission or re-transmission of data over an RF channel can result in a delay in re-accessing the RF channel. In order to address this problem, the idle-timer threshold is dynamically adjusted based on a communication system statistic to increase system performance.

Abstract: A method and system (102) provide adaptive modulation/coding with distribution of excess resources based on one or more system criteria. The system (102) may be any system with more than one modulation rate or more than one coding rate and may be a wireless communication system using CDMA, TDMA, OFDM or any other signal formats. Generally, the method determines excess resources of the system based on desired characteristics of links supported by the system. The excess resources may be any number of system resources, such as transmit power. These excess resources are then distributed to the links based on various system criteria, such as to increase system coverage, to increase system capacity, to modify a data rate profile of the system or to reduce interference in the system. Methods for providing such distribution of the excess resources are also provided for equal data rate systems.

Abstract: A Fast Fourier Transform (FFT) based voice synthesis method 110, program product and vocoder. Sounds, e.g., speech and audio, are synthesized from multiple sine waves. Each sine wave component is represented by a small number of FFT coefficients 116. Amplitude 120 and phase 124 information of the components may be incorporated into these coefficients. The FFT coefficients corresponding to each of the components are summed 126 and, then, an inverse FFT is applied 128 to the sum to generate a time domain signal. An appropriate section is extracted 130 from the inverse transformed time domain signal as an approximation to the desired output. FFT based synthesis 110 may be combined with simple sine wave summation 100, using FFT based synthesis 110 for complex sounds, e.g., male voices and unvoiced speech, and sine wave summation 100 for simpler sounds, e.g., female voices.

Abstract: Retransmissions of NAK'd frames takes place utilizing a retransmission channel (103-105). In particular, NAK'd frames are retransmitted to requesting remote units (113-115) on a channel (103-105) differing from the channel (109) in which they were originally broadcast to the remote units (113-115). Because retransmission of poorly-received frames occurs utilizing a channel that differs from the downlink multicast channel, the downlink transmission rate of the downlink channel is not reduced when retransmission needs to take place. This greatly improves data transmission to those units not requesting retransmission of data.

Abstract: A method and apparatus for reducing error propagation in digital video signals using random forced intra-refresh of macroblocks. One or more predetermined regions are defined for each digital video frame. Within each predetermined region, a number of macroblocks are selected according to a random permutation of the macroblocks within the region. The selected macroblocks are intra-coded, while the remaining macroblocks are coded according to a standard video compression protocol. This approach provides an efficient method for mitigating error propagation in a decoder. Interior regions may be smaller than exterior regions, providing higher quality for the interior regions, where sensitivity to errors is higher.

Abstract: The disclosed invention is a method to detect candidate errors within the picture start code, picture header, and picture timestamp. Upon detection, these errors may be confirmed and the impacts mitigated. An error within the timestamp bit field is adaptively detected by the use of a threshold comparison, and a mechanism for concealing the timestamp information leaves only a small timestamp anomaly. An error within the picture start code (PSC) is determined by adaptively analyzing the number of bits and the macro-block location of the next slice or GOB. If a PSC is suspected to have been overrun due to an error, this method allows for data beyond the first GOB or slice to be recovered in the frame. Depending on the extent of use of slices and GOBs, the method can recover a majority of the frame that otherwise would have been completely lost.

Abstract: A method of operating a communication system including at least two transmitting antennas and at least one receive antenna. Symbols are encoded across the at least two transmitting antennas during a coding interval. Data is received at each receive antenna and at each symbol of the coding interval. Channel gain estimates are provided between each transmitting antenna and each receive antenna at each symbol of the coding interval. An estimate of transmitted symbols is determined based on the channel gain estimates and the received data at each receive antenna at each symbol of the coding interval. An information unit is provided the estimates of the transmitted symbols to achieve spatial diversity in a communication link while mitigating channel variations.

Abstract: A receiving device and method for operating a communication system is provided. The receiving device receives a predetermined pilot sequence. The received pilot sequence is converted into at least one frequency domain pilot sequence. A plurality of time invariant channel estimates are determined from the frequency domain pilot sequence. The pilot sequence may include a null cyclic prefix. A time variant channel estimate may be determined from the time invariant channel estimates.

Abstract: A baseband detector includes a complex differential detector, a constellation point computer, and a phase shift keying (PSK) decoder. The complex differential detector outputs complex values in response to digitized samples derived from a received baseband signal. The PSK decoder generates decoded bits representing information symbols by determining in minimum distance between the complex values and plural constellation points provided by the constellation point computer. The constellation point computer can adaptively generate the constellation points based on a training sequence of information symbols and their corresponding complex valued outputs from the complex differential detector. The baseband detector can be used for frequency shifting keying (FSK) and differential phase shift keying (DPSK) demodulation in direct conversion receivers (DCRs).

Abstract: To address the need for a power modulator that can efficiently operate within a wideband, high-speed communication system, a method and apparatus for power modulation is provided herein. In accordance with the preferred embodiment of the present invention an envelope reference signal is filtered in such a way that the bandwidth is reduced while keeping the instantaneous level of the filtered signal is greater than the unfiltered envelope level. Because the bandwidth of the envelope signal is reduced, efficient operation of the switching modulator can be achieved within wideband, high-speed communication systems.

Abstract: In accordance with the preferred embodiment of the present invention a gain (A) is determined and utilized to cyclically converge upon a quotient (Q). More particularly, once A is determined, an estimate of QN is multiplied by Y to estimate {circumflex over (X)}N, where Q=X/Y. The value of {circumflex over (X)}N is then subtracted from X to determine an error (eN), which is multiplied by A. The value of AeN(n) is added to AeN(n−1) to produce an estimate of Q. Once convergence has occurred, the value for Q is output from the circuitry.