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 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.

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: A method and apparatus are disclosed for detecting a collision in a carrier sense multiple access wireless communication system. Each transmitting station includes a collision detector that evaluates one or more predefined criteria to determine when a collision has occurred. The collision detector evaluates the measured energy level and optionally payload and/or preamble detection information to determine if a collision has occurred. A collision occurred when an expected ACK message is not received, in the presence of an increased energy level and possibly preamble or payload detection information. The collision detector of the present invention can be activated, for example, at a time corresponding to the start of the 802.11 Short Inter Frame Space interval.

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: A station for a communications network. In one embodiment, the station includes a decoder, a check processor, and a transmitter. The decoder is adapted to decode a received encoded data unit. The check processor is adapted to determine whether the encoded data unit has been correctly received. The transmitter is adapted to initiate, prior to the check processor completing the determination whether the encoded data unit has been correctly received, the transmission of an acknowledgment message comprising a frame having a plurality of different fields of data. The transmitter is adapted to modify the transmission of the acknowledgment message if the check processor determines that the data unit has not been correctly received.

Abstract: A station for a communications network. In one embodiment, the station includes a decoder, a check processor, and a transmitter. The decoder is adapted to decode a received encoded data unit. The check processor is adapted to determine whether the encoded data unit has been correctly received. The transmitter is adapted to initiate, prior to the check processor completing the determination whether the encoded data unit has been correctly received, the transmission of an acknowledgment message comprising a frame having a plurality of different fields of data. The transmitter is adapted to modify the transmission of the acknowledgment message if the check processor determines that the data unit has not been correctly received.

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: A method for processing a received encoded data unit comprises: decoding the received encoded data unit; determining whether the encoded data unit has been correctly received; prior to completing the determination of whether the encoded data unit has been correctly received, initiating the transmission of an acknowledgment message; and modifying the transmission of the acknowledgment message if it is determined that the data unit has not been correctly received. In another embodiment, a station for a communications network comprises: a decoder adapted to decode a received encoded data unit; a check processor adapted to determine whether the encoded data unit has been correctly received; and a transmitter adapted to initiate the transmission of an acknowledgment message prior to the check processor completing the determination whether the encoded data unit has been correctly received.

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: 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: A method for processing a received encoded data unit comprises: decoding the received encoded data unit; determining whether the encoded data unit has been correctly received; prior to completing the determination of whether the encoded data unit has been correctly received, initiating the transmission of an acknowledgment message; and modifying the transmission of the acknowledgment message if it is determined that the data unit has not been correctly received. In another embodiment, a station for a communications network comprises: a decoder adapted to decode a received encoded data unit; a check processor adapted to determine whether the encoded data unit has been correctly received; and a transmitter adapted to initiate the transmission of an acknowledgment message prior to the check processor completing the determination whether the encoded data unit has been correctly received.

Abstract: A system for operating a communication system comprising one or more transmitters and receivers. The transmitted signals are provided with a preamble for training the receiver and/or the transmitter being in communication. The quality of the received signal is measured and compared with a threshold. If the quality is higher or lower than said threshold, a short preamble processing or a long preamble processing, respectively, is used. More than one threshold and associated pairs of preambles having different length may be used.

Abstract: A method and apparatus are disclosed for detecting a collision in a carrier sense multiple access wireless communication system. Each transmitting station includes a collision detector that evaluates one or more predefined criteria to determine when a collision has occurred. The collision detector evaluates the measured energy level and optionally payload and/or preamble detection information to determine if a collision has occurred. A collision occurred when an expected ACK message is not received, in the presence of an increased energy level and possibly preamble or payload detection information. The collision detector of the present invention can be activated, for example, at a time corresponding to the start of the 802.11 Short Inter Frame Space interval.

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.

Abstract: A thermopile on an electrically insulating substrate. A pattern is arranged on this substrate of parts which consist of a first conductive material, to which a second conductive material is applied, and parts which consist only of the first conductive material. The second material is better electrically conducting than the first and, connected as thermopile, can thereby generate a certain thermo-voltage. The second material is applied to the first, starting from a layer of the first material on the substrate, by etching stripes therein via the so-called “blind-hole etching” technique and applying the second material in these stripes.

Abstract: Mass flowmeter comprising a hollow conduit of a heat-conducting material for transporting in a determined flow direction a fluid with a mass flow rate to be measured, a first temperature-sensitive resistor element at a first position in thermal contact with this conduit for supplying heat to said fluid, a temperature sensor and measuring and control means connectable to the resistor element and the temperature sensor, wherein the temperature sensor is provided in thermal contact with the conduit at a second position upstream in relation to said first position, and the measuring and control means are adapted to maintain a constant difference in temperature at said first and second positions.

Abstract: Method for manufacturing a thermopile on an electrically insulating substrate. A pattern is arranged on this substrate of parts which consist of a first conductive material, to which a second conductive material is applied, and parts which consist only of the first conductive material.