Abstract: Aspects of this disclosure relate transmitting and/or receiving reference symbols. A first reference symbol includes a symbol and a cyclically shifted portion of the symbol, where the cyclically shifted portion has cyclic shift length. A second reference symbol includes a cyclically shifted version of the first reference symbol that is cyclically shifted relative to the first reference symbol by the cyclic shift length. The first and second reference symbols are transmitted consecutively from at least one antenna.

Abstract: Aspects of this disclosure relate receiving a reference symbol from at least one antenna. The reference symbol includes a portion of a first transmitted reference symbol and a portion of a second transmitted reference symbol. The first transmitted reference symbol includes a symbol and a cyclically shifted portion of the symbol having a cyclic shift length. The second transmitted reference symbol includes a cyclically shifted version of the first transmitted reference symbol that is cyclically shifted relative to the first transmitted reference symbol by the cyclic shift length. The reference symbol is processed. In certain embodiments, processing the reference symbol can account for (i) a frame offset between uplink symbols and downlink symbols and (ii) another timing offset between downlink transmission and uplink reception.

Abstract: Aspects of this disclosure relate receiving a reference symbol from at least one antenna. The reference symbol includes a portion of a first transmitted reference symbol and a portion of a second transmitted reference symbol. The first transmitted reference symbol includes a symbol and a cyclically shifted portion of the symbol having a cyclic shift length. The second transmitted reference symbol includes a cyclically shifted version of the first transmitted reference symbol that is cyclically shifted relative to the first transmitted reference symbol by the cyclic shift length. The reference symbol is processed. In certain embodiments, processing the reference symbol can account for (i) a frame offset between uplink symbols and downlink symbols and (ii) another timing offset between downlink transmission and uplink reception.

Abstract: Aspects of this disclosure relate transmitting and/or receiving reference symbols. A first reference symbol includes a symbol and a cyclically shifted portion of the symbol, where the cyclically shifted portion has cyclic shift length. A second reference symbol includes a cyclically shifted version of the first reference symbol that is cyclically shifted relative to the first reference symbol by the cyclic shift length. The first and second reference symbols are transmitted consecutively from at least one antenna.

Abstract: Techniques for using a narrow filter located before a power amplifier to reduce interference in an adjacent frequency band are disclosed. In an exemplary design, an apparatus (e.g., a wireless device) includes the narrow filter and the power amplifier. The narrow filter is for a first frequency band (e.g., Band 40) and has a first bandwidth that is more narrow than the first frequency band. The narrow filter receives and filters an input radio frequency (RF) signal and provides a filtered RF signal. The power amplifier receives and amplifies the filtered RF signal and provides an amplified RF signal. The apparatus may further include a full filter for the first frequency band and located after the power amplifier. The full filter receives and filters the amplified RF signal and provides an output RF signal when it is selected for use.

Abstract: Methods and apparatus for multiple wireless service coexistence are disclosed. The disclosed methodology and accompanying apparatus serve to engage one or more switching devices to connect/disconnect a first service transmitter to a first antenna, connect/disconnect a dual mode receiver and second service transmitter from the first antenna, connect/disconnect the second service transmitter from a second antenna, and connect/disconnect a diversity receiver to the second antenna. A first service transmit signal in a first service can then be transmitted or received using the first antenna, and a second service receive signal in a second service can be transmitted or received using the second antenna and the diversity receiver.

Abstract: An apparatus and method are disclosed for effectively and efficiently arbitrating concurrent usage between WLAN and Bluetooth access technologies for co-located wireless devices. A state level arbiter determines state and relevant parameters of a WLAN module and of a Bluetooth module of a wireless transceiver unit. The state level arbiter uses the state and relevant parameters to determine which access technology (WLAN or Bluetooth) or combination of the access technologies (WLAN or Bluetooth) will provide the best concurrent performance for wireless transmissions at a given time for specific Bluetooth states and WLAN states.

Abstract: Techniques for using a narrow filter located before a power amplifier to reduce interference in an adjacent frequency band are disclosed. In an exemplary design, an apparatus (e.g., a wireless device) includes the narrow filter and the power amplifier. The narrow filter is for a first frequency band (e.g., Band 40) and has a first bandwidth that is more narrow than the first frequency band. The narrow filter receives and filters an input radio frequency (RF) signal and provides a filtered RF signal. The power amplifier receives and amplifies the filtered RF signal and provides an amplified RF signal. The apparatus may further include a full filter for the first frequency band and located after the power amplifier. The full filter receives and filters the amplified RF signal and provides an output RF signal when it is selected for use.

Abstract: Techniques for mitigating VCO pulling are described. In an aspect, VCO pulling may be mitigated by (i) injecting an oscillator signal, which is a version of a VCO signal from a VCO, into a transmitter and (ii) using coupling paths from the transmitter to the VCO to re-circulate the oscillator signal back to the VCO. In one design, an apparatus includes a VCO and a coupling circuit. The VCO generates a VCO signal at N times a desired output frequency. The coupling circuit receives an oscillator signal generated based on the VCO signal and injects the oscillator signal into a transmitter to mitigate pulling of the frequency of the VCO due to undesired coupling from the transmitter to the VCO. The apparatus may include a phase adjustment circuit that adjusts the phase of the oscillator signal and/or an amplitude adjustment circuit that adjusts the amplitude of the oscillator signal.

Abstract: An apparatus and method for multiple wireless service coexistence comprising: engaging a first switch to connect a first service transmitter to an antenna through a first filter path and to disconnect a first service receiver from the antenna; engaging a second switch to connect a second service receiver to the antenna through a second filter path and to disconnect a second service transmitter from the antenna; enabling transmit power control on the first service transmitter; and performing one or both of the following: a) transmitting a first service transmit signal through the first filter path to the antenna with high rejection of the band of a second service; b) receiving a second service receive signal through the second filter path from the antenna with high rejection of the band of a first service.

Abstract: An apparatus and method are disclosed for effectively and efficiently arbitrating concurrent usage between WLAN and Bluetooth access technologies for co-located wireless devices. A state level arbiter determines state and relevant parameters of a WLAN module and of a Bluetooth module of a wireless transceiver unit. The state level arbiter uses the state and relevant parameters to determine which access technology (WLAN or Bluetooth) or combination of the access technologies (WLAN or Bluetooth) will provide the best concurrent performance for wireless transmissions at a given time for specific Bluetooth states and WLAN states.

Abstract: Techniques for mitigating VCO pulling are described. In an aspect, VCO pulling may be mitigated by (i) injecting an oscillator signal, which is a version of a VCO signal from a VCO, into a transmitter and (ii) using coupling paths from the transmitter to the VCO to re-circulate the oscillator signal back to the VCO. In one design, an apparatus includes a VCO and a coupling circuit. The VCO generates a VCO signal at N times a desired output frequency. The coupling circuit receives an oscillator signal generated based on the VCO signal and injects the oscillator signal into a transmitter to mitigate pulling of the frequency of the VCO due to undesired coupling from the transmitter to the VCO. The apparatus may include a phase adjustment circuit that adjusts the phase of the oscillator signal and/or an amplitude adjustment circuit that adjusts the amplitude of the oscillator signal.

Abstract: An apparatus for receiving signals includes a low noise amplifier (LNA) configured to receive a radio frequency (RF) signal. An I/Q direct down converter is coupled to the LNA. The I/Q direct down converter is configured to split the RF signal into real and imaginary components and to down convert the real and imaginary components directly to baseband signals. A local oscillator (LO) is coupled to the I/Q direct down converter and is configured to drive the I/Q direct down converter. First and second filters are coupled to the I/Q direct down converter. The first and second filters are configured to filter the down converted real and imaginary components, respectively. First and second analog-to-digital converters (ADCs) are coupled to the first and second filters, respectively. The first and second ADCs are configured to convert the real and imaginary components into digital signals.

Abstract: A zero intermediate frequency radio receiver that comprises mixing stages, an A to D converter, a digital demodulator, a carrier tracking system and a carrier nulling system is disclosed. The mixing stages receive FM or PM signals and produce analogue in-phase and quadrature baseband signal which are in turn converted to digital baseband signals by the A to D convertor. DC offsets in the baseband signals are removed by high pass filtering prior to demodulation. Tracking enables the baseband signals to be maintained at a centre frequency of substantially zero hertz, while signal strength at this frequency is minimized or mulled before the DC offset filtering. Information which might otherwise be removed by the filtering is thereby retained in the baseband signals, which are relatively less distorted.