A method and apparatus for increasing the data rate and providing antenna diversity using multiple transmit antennas utilize a set of bits of a digital signal to generate a codeword. Delay elements may be provided in antenna output channels, or, with suitable code construction, delay may be omitted. n signals represent n symbols of a codeword are transmitted with n different transmit antennas. At the receiver, the noisy received sequence is decoded. The parallel transmission and channel coding enables an increase the data rate over previous techniques, and recovery even under fading conditions. The channel coding may be concatenated with error correction codes under appropriate conditions.

An adaptable orthogonal frequency-division multiplexing system (OFDM) that uses a multiple input multiple output (MIMO) to having OFDM signals transmitted either in accordance with time diversity to reducing signal fading or in accordance with spatial diversity to increase the data rate. Sub-carriers are classified for spatial diversity transmission or for time diversity transmission based on the result of a comparison between threshold values and at least one of three criteria. The criteria includes a calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix.

A simple block coding arrangement is created with symbols transmitted over a plurality of transmit channels, in connection with coding that comprises only simple arithmetic operations, such as negation and conjugation. The diversity created by the transmitter utilizes space diversity and either time or frequency diversity. Space diversity is effected by redundantly transmitting over a plurality of antennas, time diversity is effected by redundantly transmitting at different times, and frequency diversity is effected by redundantly transmitting at different frequencies: Illustratively, using two transmit antennas and a single receive antenna, one of the disclosed embodiments provides the same diversity gain as the maximal-ratio receiver combining (MRRC) scheme with one transmit antenna and two receive antennas. The principles of this invention are applicable to arrangements with more than two antennas, and an illustrative embodiment is disclosed using the same space block code with two transmit and two receive antennas.

The present invention relates to a transmission and receiving method and apparatus using a dynamically determined Inter-Frame Space (IFS) in a Wireless Local Area Network (WLAN). According to one aspect of the present invention, a method for processing a received frame by a Station (STA) in a WLAN may include receiving a first frame including downlink data for a plurality of STAs, if the received first frame has no error, transmitting a second frame including an ACKnowledgement (ACK) of the STA simultaneously with ACKs of one or more other STAs, and if the received first frame has an error, performing carrier sensing using a variably determined IFS.

Embodiments of the present invention disclose a signal processing method and a base station. The method may include: performing, by a base station, packet assembly, code modulation, and multi-antenna processing on downlink channel data, so as to form antenna port signals. The method may also include performing, by the base station, orthogonal transform on the antenna port signals according to a preset matrix used for orthogonal transform, and simultaneously sending, by the base station, orthogonally transformed antenna port signals to user equipment by using different antennas, where cells covered by the different antennas have a same cell identity.

In a method implemented in a communication device configured to transmit PHY data units via a communication channel, first data and second data is received. The first data is modulated according to a first constellation having a first number of constellation points, and the second data is modulated according to a second constellation having a second number of constellation points higher than the first number of constellation points. The first data and the second data is parsed to a plurality of spatial streams such that a first subset of the spatial streams includes at least some of the modulated first data but none of the modulated second data, and a second subset of the spatial streams includes at least some of the modulated second data but none of the modulated first data. A single PHY data unit that includes the plurality of spatial streams is generated.

Acknowledgment and/or receiver recovery mechanisms for scheduled responses within multiple user, multiple access, and/or MIMO wireless communications. Explicit scheduling information is provided from a first wireless communication device (e.g., an access point (AP), a transmitting wireless communication device) to a number of other wireless communication devices (e.g., wireless stations (STAs), receiving wireless communication devices) directing those other wireless communication devices a manner by which responses (e.g., acknowledgments (ACKs), block acknowledgments (BACKs), training feedback frames, etc.) are to be provided to the first wireless communication device there from. Such direction may include the order, timing, cluster assignment, etc. by which each respective wireless communication device is to provide its respective response to the first wireless communication device. In the event of the first wireless communication device failing to receive at least one response from at least one of the other wireless communication devices, various communication medium recovery mechanisms may be performed.

A method and an apparatus for transmitting broadcast signals thereof are disclosed. The method for transmitting broadcast signals includes processing input streams into BB frames in PLPs; encoding data of the PLPs; building at least one signal frame by mapping the encoded data of the PLPs; and modulating data in the built signal frame by OFDM method and transmitting the broadcast signals having the modulated data, wherein at least one of the BB frames includes a stuffing field and a first indicator describing whether the stuffing field is included in the BB frame.

The present invention employs a pilot scheme for frequency division multiple access (FDM) communication systems, such as single carrier FDM communication systems. A given transmit time interval will include numerous traffic symbols and two or more short pilot symbols, which are spaced apart from one another by at least one traffic symbol and will have a Fourier transform length that is less than the Fourier transform length of any given traffic symbol. Multiple transmitters will generate pilot information and modulate the pilot information onto sub-carriers of the short pilot symbols in an orthogonal manner. Each transmitter may use different sub-carriers within the time and frequency domain, which is encompassed by the short pilot symbols within the transmit time interval. Alternatively, each transmitter may uniquely encode the pilot information using a unique code division multiplexed code and modulate the encoded pilot information onto common sub-carriers of the short pilot symbols.

Methods and devices are provided for MIMO OFDM transmitter and receivers having odd and/even numbers of transmit antennas. Various methods for pre-coding information bits before space time coding (STC) are described for enabling transmission of information bits over all antennas. Methods of decoding received signals that have been pre-coded and STC coded are also provided by embodiments of the invention. Pilot patterns for downlink and uplink transmission between a base station and one or more wireless terminals for three transmit antenna transmitters are also provided. Variable rate codes are provided that combine various fixed rate codes in a manner that results in codes whose rates are dependent on all the various fixed rate codes that are combined.