Agere Systems Inc.

Edward E Campbell

Syed Aon Mujtaba

Roman Zbigniew Arkiszewski

Gil Ra'anan

Methods and apparatus are provided for per-antenna training in a multiple antenna communication system having a plurality of transmit antenna branches. A long training sequence is transmitted on each of the transmit antenna branches such that only one of the transmit antenna branches is active at a given time. The active transmit antenna branch is configured in a transmit mode during the given time and one or more of the inactive transmit antenna branches are configured in a receive mode during the given time. The transmit and receive modes are configured, for example, by applying a control signal to one or more switches.

Method and apparatus for improved antenna isolation for per-antenna training using transmit/receive switch

Methods and apparatus are provided for per-antenna training in a multiple antenna communication system having a plurality of transmit antenna branches. A long training sequence is transmitted on each of the transmit antenna branches such that only one of the transmit antenna branches is active at a given time. The active transmit antenna branch transmits the long training sequence with an increased power level relative to a transmission of a payload by the active transmit antenna branch. The increased power level for the active transmit antenna branch compensates for the inactive transmit antenna branches being silent during the given time. Thus, the active transmit antenna branch provides approximately the same antenna power while transmitting the long training sequence as a total power of the plurality of transmit antenna branches during a transmission of the payload. The increased power level can be provided, for example, by a digital-to-analog converter associated with the active transmit antenna branch.

Method and apparatus for improved antenna isolation for per-antenna training using variable scaling

The sideband used by a low-intermediate-frequency transmitter for transmitting signals on a channel is selectable. In some embodiments of the invention, the sideband used for transmitting signals is selected based on the location of the channel within a band of channels. In such embodiments, the lower sideband may be selected for transmitting signals if the channel is the lowest-frequency channel in the band, and the upper sideband may be selected for transmitting signals if the channel is the highest-frequency channel in the band. Such sideband selection results in image power falling within the band, which can be helpful in complying with out-of-band power limitations.

Selectable sideband transmission

A low IF mixer and method for down-converting a signal at a desired frequency are disclosed with improved selectivity performance. The energy of sidebands on each side of the desired frequency is evaluated; and a local oscillator frequency is selected based on the evaluation of the energy. Generally, the local oscillator frequency associated with the sideband having a lower energy is selected. The desired frequency may have a frequency of RF and the sidebands have a frequency of the desired frequency plus or minus an offset frequency (RF+IF or RF&#x2212;IF). The signal at the desired frequency may be multiplied by the selected local oscillator frequency to down-convert the signal.

Low IF mixer with improved selectivity performance

A low cost, robust method and apparatus for controlling the gain of a power amplifier to compensate for changes that are gradual with time. The bias circuit of a power amplifier is sent one of three signals in response to a measurement of the average output power level of the power amplifier. If the average output power lever is less than a desired value, a signal to increment the bias current by a set amount is sent, so that the output power increases. If the average output power lever is more than the desired value, a signal to decrement the bias current by a set amount is sent. A third signal may be sent that causes the bias circuit to reset to a default value. The three signals may be sent as a two bit digital signal.

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Blandon, PA, United States of America

Edward E Campbell