Abstract: 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.

Abstract: A method for controlling a data transmission rate of at least one transceiver in a wireless system, the transceiver including a transmitter and a receiver, the method including the steps of: 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 through the wireless communication channel; and modifying a data transmission rate of the transmitter as a function of the signal quality characteristic.

Abstract: 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.

Abstract: This invention relates to controlling the power states in a multimedia system comprising a multimedia connector box including a multimedia source interconnected to a transmitter module, and a multimedia device including a receiver module interconnected to a multimedia sink, wherein the transmitter and the vice via multimedia interfacing means. A signal detector detects the signal activity between the power sources of the multimedia system for determining the current power state of the power sources, and a power switching mechanism adapts the power states of the transmitter and receiving modules to the power states of the power sources.

Abstract: A method and apparatus are disclosed for transmitting symbols in a multiple antenna communication system according to a frame structure, 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). The disclosed frame structure comprises a legacy preamble having at least one long training symbol and N-I additional long training symbols that are transmitted on each of N transmit antennas. The legacy preamble may be, for example, an 802.11 a/g preamble that includes at least one short training symbol, at least one long training symbol and at least one SIGNAL field. A sequence of each of the long training symbols on each of the N transmit antennas are time orthogonal. The long training symbols can be time orthogonal by introducing a phase shift to each of long training symbols relative to one another.

Abstract: 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.

Abstract: 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.

Abstract: Methods and systems are disclosed for space interleaved communication of data in a multiple antenna communication system. Data is interleaved over space by interleaving the data over a plurality of transmit branches in the multiple antenna system. The disclosed spatial interleaving increases the performance gains resulting from the spatial transmit diversity of the multiple antenna communication system. Spatial interleaving can be performed, for example, over the bits before the bits are interleaved over frequency. In another variation, spatial interleaving is performed over the symbols after the bits are mapped to symbols.

Abstract: 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.

Abstract: 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.

Abstract: 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.