Abstract: A method for enabling asset tracking that includes the steps of: receiving (910) a first excitation signal at a first power level using a first frequency band; and (920) upon determining that a first set of parameters is satisfied, awakening from an inactive mode to an active mode, transmitting data at a second power level that is greater than the first power level using a second frequency band that is different from the first frequency band, and returning to the inactive mode, wherein determining that the first set of parameters is satisfied comprises at least determining that the first excitation signal corresponds to a first wake-up circuit.

Abstract: The present invention is a method and apparatus for voice communication. Vocoded frames are transmitted using a transmission intervals. Each transmission interval is split into a first interval portion and a second interval portion. Code symbols associated with each vocoded frame are divided into a group A and a group B. The method includes transmitting group A code symbols of a first vocoded frame using a first interval portion of an interval i; decoding the group A code symbols received at the first interval portion of the interval i; performing an error detection code check on the first interval portion of the interval i; generating and sending a negative acknowledgment signal when the first interval portion of the interval i fails the error detection code check; and transmitting group B code symbols of the first vocoded frame using a second interval portion of an interval i+N.

Abstract: A transmitting device (100) transmits a first packet, comprising a second encryption vector, that is encrypted using a first encryption vector. The transmitting device transmits a second packet that is encrypted using the second encryption vector if an acknowledgement message is received within a predetermined time after transmitting the first packet; otherwise, the first packet is re-transmitted. Upon receipt of the first packet, a receiving device (102) decrypts the first packet using the first encryption vector and transmits the acknowledgement message. Upon receipt of the second packet; the receiving device attempts to decrypt a portion of the second packet using the first and second encryption vectors. If the portion of the second packet was successfully decrypted using the first encryption vector, the receiving device re-transmits the acknowledgement message for the first packet; otherwise, it transmits an acknowledgement message for the second packet.

Abstract: A system (100) that includes a device (120), such as an access point, which is configured for: obtaining (210) a status of a busy channel indicator; and dynamically selecting (220) an access scheme within a contention free period interval based on the status of the busy channel indicator.

Abstract: Methods for delivery of multicast packets in a wireless communication system are disclosed. The methods comprise transmitting a contention free period initiation signal from an access point to the station, transmitting broadcast packets from the access point to the station, transmitting multicast packets from the access point to the station and holding the multicast packets in storage after the transmission, transmitting a contention free period end signal from the access point to the station, determining if a negative acknowledgement message has been received, retransmitting the multicast packets in response to receiving a negative acknowledgment message, and eliminating the multicast packets at a next beacon interval.

Abstract: A method and system for wireless data transmission between at least three stations use multiple frequency bands for simultaneous channel communications. The method includes transmitting a Request To Send (RTS) packet from a first station to an intermediate second station over a first frequency band. Two Clear To Send (CTS) packets, which CTS packets include transmission timing information, are then transmitted from the second station simultaneously both to the first station and to a third station. The CTS packet sent to the first station is transmitted over the first frequency band and the CTS packet sent to the third station is transmitted over a second frequency band. A data packet from the first station is then transmitted to the second station. The third station suspends, based on the transmission timing information included in the CTS packets, any unicast transmission to the second station during the transmission of the data packet from the first station to the second station.

Abstract: A method and apparatus for communicating in an OFDM system whereby data subcarriers associated with a first antenna of at least two transmit antennas are multiplexed with data symbols while modulating other subcarriers associated with other antennas with zero. The data subcarriers are separated between the at least two transmit antennas so that a data subcarrier and a mirror data subcarrier are not transmitted from a same transmit antenna and that adjacent data subcarriers are at least two subcarrier frequency bandwidths apart. In an embodiment, the method and apparatus further comprise receiving the transmitted subcarriers from at least two receive antennas where the transmitted data subcarriers are also separated so that the data subcarrier and the mirror data subcarrier are not received from a same receive antenna of the at least two receive antennas. The method and apparatus further comprises combining the received transmitted subcarriers from the at least two receive antennas into a single data stream.

Abstract: A receiver (200) is provided receiving signals from differing base stations (BTSA and BTSB). The signal from BTSA is encoded using a first rate convolutional encoder while the signal transmitted from BTSB is encoded using a second rate convolutional encoder. Since the multiple base station links may result in a different number of symbols being received for each bit transmitted, the symbols received for each link cannot be simply combined. Therefore, in the preferred embodiment of the present invention, the resulting symbols are passed to multiple branch metric circuits (210–211), where branch metrics (?i) for the symbols are obtained. After the ith branch metrics for the base stations are computed, the branch metrics for each base station are passed to a combiner (212) where they are combined.

Abstract: An automatic gain control includes a digital lowpass filter for filtering a series of digital samples generated by an analog-to-digital converter to generate a lowpass filtered digital sample series; a power averager coupled to the digital lowpass filter for calculating an average power of the lowpass filtered digital sample series; and a lookup table coupled to the power averager for setting a selectable gain of an amplifier coupled to the analog-to-digital converter as a function of the average power.

Abstract: A method and apparatus for frequency correction of a signal in a wireless local area network (WLAN) communication system is disclosed. The signal is processed to determine a frequency offset estimate which is a frequency deviation of the signal from a local oscillator. The signal is then shifted by an amount corresponding to a frequency correction estimate where the frequency correction estimate is an averaged value of the frequency offset estimate and at least one prior frequency offset estimate. Finally, the frequency correction estimate is utilized to correct signals in the WLAN communication system.

Abstract: A method and apparatus for communicating in an OFDM system whereby subcarriers of the OFDM system are multiplexed between at least a first and a second transmit antenna. The subcarriers are separated between the at least two transmit antennas so that a subcarrier and a mirror subcarrier are not transmitted on the same transmit antenna and that adjacent subcarriers on the same antenna are at least two subcarrier frequency bandwidths apart. The method and apparatus for communicating is compatible with either a single receive antenna or with more than one receive antennas. In an embodiment, the method and apparatus further includes receiving the transmitted subcarriers from at least a first and second receive antenna. The subcarriers may also be separated so that the subcarrier and the mirror subcarrier are not received from the same receive antenna and that adjacent subcarriers on the same antenna are at least two subcarrier frequency bandwidths apart.

Abstract: A communication band is divided into a plurality of allocation channels (202, 204, 206, 208). At least one allocation channel (204) is transferred to a transform domain. The behavior of the at least one allocation channel is monitored in the transform domain in order to derive a set of statistics. The set of statistics are used to determine a channel category for the at least one allocation channel.

Abstract: A method and apparatus for reuse of pseudo-random noise (PN) offsets within a cell of a wireless communication system such as a multi-sector CDMA system. Adaptive antenna arrays are employed to form the multiple sector areas within the CDMA cell. A forward link data channel is established between a mobile unit and a base station via sectors that share or reuse comment PN offsets, thereby providing desirable transmit diversity.

Abstract: A method and apparatus to adaptively puncture bits within QAM modulated data symbols transmitted in a communication system in order to effect a signaling channel. The method and apparatus utilize inherent characteristics of a particular mapping scheme for the QAM constellation to selectively puncture particular bits within a data symbol with signaling information and predetermined binary values to selectively increase the log-likelihood ratio gains of those particular bits punctured with the signaling information. The log-likelihood ratios are used to obtain the signaling information and, thus, increasing the gain of the log-likelihood ratios affords greater reliability for the signaling information without increasing the required system resources.

Abstract: At a first device (102 or 104), a message is received and processed. If the message is processed during a first time period, the first device transmits an acknowledgement message during a second time period; otherwise the first device transmits the acknowledgment message during a third time period. The second time period and the third time period are exclusive of each other.

Abstract: A receiving communication device synchronizes to a timing reference of a transmitting communication device based on a determined timing error. The receiving communication device determines the timing error by processing a synchronization signal via a first stage filtering and interpolation process that includes predetermined coefficients and a second stage interpolation process that includes a minimal number of dynamically determined coefficients. By dividing the process into a predetermined coefficient stage and a dynamically determined coefficient stage, the receiving communication device is able to make timing adjustments in a more efficient manner, that is, at a lesser processor loading, than a communication device in which all filtering and interpolation coefficients are dynamically determined.

Abstract: Methods and systems are provided for transmission power control in a multiple access communication system, providing power ramping of a noise floor power level in advance of a high data rate transmission, at a comparatively higher power level, by a mobile station. The preferred method includes receiving a request at a base transceiver station (BTS) for a data transmission by a first mobile station of a plurality of mobile stations (300), the data transmission to have a predetermined data transmission power level; measuring a noise floor power level (305); and comparing the measured noise floor power level to the predetermined data transmission power level (310).

Abstract: A transmitting device (100) transmits a first packet, comprising a second encryption vector, that is encrypted using a first encryption vector. The transmitting device transmits a second packet that is encrypted using the second encryption vector if an acknowledgement message is received within a predetermined time after transmitting the first packet; otherwise, the first packet is re-transmitted. Upon receipt of the first packet, a receiving device (102) decrypts the first packet using the first encryption vector and transmits the acknowledgement message. Upon receipt of the second packet; the receiving device attempts to decrypt a portion of the second packet using the first and second encryption vectors. If the portion of the second packet was successfully decrypted using the first encryption vector, the receiving device re-transmits the acknowledgement message for the first packet; otherwise, it transmits an acknowledgement message for the second packet.

Abstract: A method and system for dynamic rate switching via medium access channel layer signaling is disclosed, wherein data rates for high data rate channels are automatically shifted up or down based on a predetermined metric. In a preferred embodiment, data rates are automatically shifted up or down based on transmit channel gain required to maintain a required signal to noise ratio.

Abstract: A method and apparatus to efficiently calculate log-likelihood ratios for each bit within M-ary QAM modulated symbols transmitted in a communication system. The method and apparatus utilize characteristics of square Karnaugh mapping of the QAM symbol constellation in order to reduce the number of distance calculations needed to determine the log-likelihood ratios for each of the bits within a demodulated symbol. The reduction in the number of calculations affords significant reduction in the time needed to determine log-likelihood ratios, especially for higher order M-ary QAM systems.