Agere Systems Inc.

Avago Technologies General IP (Singapore) Pte. Ltd.

Bas Driesen

Jan Boer

Kai Roland Kriedte

Ra'anan Gil

Tim Schenk

Allert Van Zelst

Robert John Kopmeiners

Joseph H Havens

A method and apparatus are provided for transmitting one or more symbols in a multiple antenna wireless communication system. Subcarriers from one or more symbols are interleaved across a plurality of antennas. The symbols may be, for example, long or short training symbols based on a single-antenna long or short training symbol, respectively, and wherein each subsequent subcarrier from the single-antenna training symbol is positioned in a training symbol for a logically adjacent antenna. One or more additional subcarriers may be inserted in at least one of the plurality of symbols to allow nulled subcarriers to be estimated using an interpolation-based channel estimation technique. The remaining portions of a header, as well as the data sequences of a packet, may also be diagonally loaded.

Method and apparatus for communicating symbols in a multiple input multiple output communication system using interleaved subcarriers across a plurality of antennas

A method for controlling a transmission rate of at least one transceiver, the transceiver including a transmitter and a receiver, includes: determining a signal quality characteristic corresponding to a signal received at the receiver by measuring a difference between one or more reference constellation points and one or more received constellation points, and modifying a transmission rate of the transmitter over a wireless communication channel as a function of the signal quality characteristic. The step of modifying the transmission rate over the wireless communication channel includes: determining lower and upper threshold levels representing reference minimum and maximum signal quality characteristics, respectively, corresponding to the transmission rate; maintaining the transmission rate when the measured signal quality characteristic is between the lower and upper threshold levels; and increasing the transmission rate when the signal quality characteristic is less than one or more lower threshold levels associated with one or more corresponding higher transmission rates.

Data transmission rate adaptation in a wireless communication system

In a wireless system including a wireless communication channel, a method for estimating a signal quality of a received signal includes the steps of receiving a signal from the wireless communication channel, the received signal including at least one field that is modulated and encoded in a substantially fixed manner, and generating at least one reference field based, at least in part, on the at least one field and on a channel estimation signal. The channel estimation signal is representative of at least one characteristic of the wireless communication channel. The method further includes the step of generating a signal quality estimate as a function of the at least one field in the received signal and the generated at least one reference field.

Signal quality estimation in a wireless communication system

A method and apparatus are disclosed for transmitting symbols in a multiple antenna wireless communication system, such that the symbols can be interpreted by a lower order receiver (i.e., a receiver having a fewer number of antennas than the transmitter). For example, subcarriers from one or more symbols can be transmitted such that each of the subcarriers are active on only one of the antennas at a given time. In one implementation, the subcarriers are diagonally loaded across logically adjacent antennas. The symbols can include one or more long training symbols and optionally a SIGNAL field that indicates a duration that a receiver should defer until a subsequent transmission. In this manner, a transmitter in accordance with the present invention may be backwards compatible with a lower order receiver and a lower order receiver can interpret the transmitted symbols or defer for an appropriate duration.

Methods and apparatus for backwards compatible communication in a multiple input multiple output communication system with lower order receivers

Methods and apparatus are disclosed for DC offset estimation and for DC offset compensation that collectively reduce or eliminate the distortion of subcarriers due to DC offset in an OFDM receiver. The DC offset estimation is obtained by subtracting a sum of time domain samples of an OFDM symbol for two consecutive OFDM symbols or subtracting a known transmitted OFDM symbol and a frequency domain representation of a received version of the known OFDM symbol (at least one of which is adjusted to compensate for channel distortion). The DC offset compensation is accomplished by removing the estimated DC offset from the received signal. The DC estimation process and the DC compensation process can be connected in disclosed feed-forward or feedback configurations.

Method and apparatus for estimating DC offset in an orthogonal frequency division multiplexing system

In a wireless system comprising at least one transceiver configurable for communication over a wireless communication channel, the transceiver comprising a transmitter and a receiver, a method for controlling a data transmission rate of the at least one transceiver comprises the steps of: (i) determining a signal quality characteristic corresponding to a signal received at the receiver by measuring a difference between one or more reference constellation points and one or more received constellation points, the signal quality characteristic representing an estimation of signal degradation; and (ii) modifying a data transmission rate of the transmitter based, at least in part, on the signal quality characteristic.

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Dongen, Netherlands

Bas Driesen