Abstract: The invention relates to a detection method using a receiver of a digital communication system for the detection of a symbol from a received signal, which signal is transmitted by a transmitter of the digital communication system, wherein the symbol is a selected symbol out of a predetermined set of symbols and wherein each symbol of the predetermined set comprises a sequence of chips wherein each of the chips is PSK-modulated according to a selected modulation code.

Abstract: A method and apparatus are disclosed for transmitting symbols in a multiple antenna communication system. The disclosed frame structure comprises a preamble having a plurality of long training symbols that are transmitted on a plurality transmit antennas. At least a portion of the frame is delayed on at least one transmit antenna. The disclosed frame formats of the present invention are backwards compatible to existing single antenna communication systems. The delay amount, D, can be approximately equal to one OFDM time sample period, T. The delayed version can be obtained by introducing a time delay into a signal on the delayed branch(es) or by cyclically shifting at least a portion of each frame on the delayed branch(es). The entire frame or only the preamble portion of each frame can be delayed.

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 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-1 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: 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: The invention relates to a detection method using a receiver of a digital communication system for the detection of a symbol from a received signal, which signal is transmitted by a transmitter of the digital communication system, wherein the symbol is a selected symbol out of a predetermined set of symbols and wherein each symbol of the predetermined set comprises a sequence of chips wherein each of the chips is PSK-modulated according to a selected modulation code.

Abstract: Detection of a symbol from a received signal wherein the symbol is a selected symbol out of a predetermined set of symbols, wherein each symbol of the predetermined set is a complementary coded keying (CCK) symbol having a sequence of chips wherein each of the chips is phase shift keying (PSK)-modulated according to a selected modulation code wherein each of the selected modulation codes has a first sub-modulation code which is a selection from a plurality of first sets of predetermined phase modulating elements and a second sub-modulation code which is a selection from one second set of predetermined phase modulating elements wherein at least one of the predetermined phase modulating elements of the second set is a complex value such as defined in the high speed IEEE 802.11b standard, wherein a modulation code is selected from the modulation codes which correlates according to a correlation method with the received signal.

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: The invention relates to a method for the detection of a symbol from a received signal wherein the symbol is a selected symbol out of a predetermined set of symbols, wherein each symbol of the predetermined set is a CCK symbol comprising a sequence of chips wherein each of the chips is PSK-modulated according to a selected modulation code wherein each of the selected modulation codes comprises a first sub-modulation code which is a selection from a plurality of first sets of predetermined phase modulating elements and a second sub-modulation code which is a selection from one second set of predetermined phase modulating elements wherein at least one of said predetermined phase modulating elements of said second set is a complex value such as defined in the high speed IEEE 802.11b standard, wherein a modulation code is selected from said modulation codes which correlates according to a correlation method with the received signal.

Abstract: The invention relates to a detection method using a receiver of a digital communication system for the detection of a symbol from a received signal which signal is transmitted by a transmitter of the digital communication system, wherein the symbol is a selected symbol out of a predetermined set of symbols and wherein each symbol of the predetermined set comprises a sequence of chips wherein each of the chips is PSK-modulated according to a selected modulation code.

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 receiver, and a method for operating the receiver, for a station in a wireless local area network using a common wireless communication channel and employing a CSMA/CA (carrier sense multiple access with collision avoidance) protocol includes various modes. In normal mode, the receiver follows typical states in order to detect a message and demodulate data from the message properly. Meanwhile, a process implements a message-in-message (MIM) mode when an energy increase above a specified level is detected. While in the MIM mode, if a carrier is detected, the energy increase is caused by a new message; otherwise, the energy increase is caused by an interfering station. If the carrier is detected, the receiver begins retraining so that it can start receiving the new message as soon as the first message ends. If no carrier is detected, the receiver waits a specified time to detect a carrier or for the end of the first message, after which the receiver returns to the beginning of the normal mode.

Abstract: For use in an automatic gain control that receives a digital signal from a digital circuit having a given dynamic range and develops therefrom a gain signal to be applied to a variable gain amplifier, an analyzing circuit for, and method of, determining a magnitude of the gain signal.