Abstract: A base station for use in wireless network that communicating with subscriber stations according to a multicarrier protocol. The base station receives uplink signals transmitted by the subscriber stations and measures the channel quality of each uplink acknowledgment signal channel. The base station transmits to a first subscriber station a control message that assigns the first subscriber station to transmit a first acknowledgment signal in a first selected uplink acknowledgment signal channel. The base station selects the first selected uplink acknowledgment signal channel based on a first measured channel quality associated with the first selected uplink acknowledgment signal channel.

Abstract: A base station for use in a wireless network that communicates according to a multi-carrier protocol. The base station receives an uplink signal transmitted by a first subscriber station. The first subscriber station transmits using a configurable spectral shaping filter and a selectable modulation order. The base station determines a required bandwidth efficiency associated with the first subscriber station and, in response to the determination, selects a first modulation order and a first filter parameter to be used by the first subscriber station. Advantageously, the base station selects the first modulation order and the first filter parameter in order to maximize a power efficiency of the first subscriber station while maintaining the required bandwidth efficiency.

Abstract: In a wireless network comprising a plurality of subscriber stations and a base station capable of providing service to the subscriber stations, a subscriber station is provided that includes a rank selector and a scheduling data reporter. The rank selector is operable to select a rank for the subscriber station. The rank is operable to identify a number of antennas for transmitting data streams from the base station to the subscriber station. The scheduling data reporter is operable to report scheduling data, including the rank, to the base station.

Abstract: A method of generating beam-forming weights in an orthogonal frequency division multiplexing network is provided. The method includes generating a plurality of sub-bands. Each sub-band comprises a plurality of sub-carriers. A single beam-forming weight is generated for each sub-band.

Abstract: A method of providing adaptive modulation and coding in a multi-carrier wireless network that includes a plurality of subscriber stations is provided. The method includes, for each of the subscriber stations, selecting a type of modulation and a coding rate based on a signal-to-interference-plus-noise ratio (SINR) variance.

Abstract: A method of wireless communication is provided. The method comprises adaptively polling a plurality of subscriber stations to provide channel quality indications for a plurality of channels associated with at least a portion of an orthogonal frequency division multiple access wireless network and adjusting the at least a portion of the orthogonal frequency division multiple access wireless network based on the channel quality indications.

Abstract: A method for performing a soft handoff for a mobile station from a source base station to a target base station in an Orthogonal Frequency-Division Multiple Access (OFDMA) wireless network that is capable of communicating with a plurality of mobile stations in a coverage area of the OFDMA wireless network is provided. The method includes determining whether a relative delay between receipt of a source pilot signal from a source base station and receipt of a target pilot signal from a target base station is less than a downlink coherence time. When the relative delay is less than the downlink coherence time, the soft handoff is performed.

Abstract: A hybrid beamforming apparatus and method are proposed for a communication system. The hybrid beamforming apparatus includes a plurality of antennas, a plurality of FFT, a plurality of hybrid weight-coefficient generators and a plurality of adders. In each of the hybrid weight-coefficient generators, the weight coefficient for each subcarrier is calculated by a time-domain correlation matrix and a cross-correlation vector, which is calculated by a frequency domain signal and a training signal. The hybrid beamforming apparatus and method according to the present invention can enhance immunity for multipath effect with lower system complexity.

Abstract: A base station for use in an OFDM network capable of communicating with a plurality of subscriber stations in a coverage area of the OFDM network. The base station transmits to a first subscriber station in a first subband of subcarriers from a first transmit antenna and transmits to the first subscriber station in a second subband of subcarriers from a second transmit antenna. The first and second subbands comprise different subcarriers. The base station also transmits to a second subscriber station in the first subband of subcarriers from the second transmit antenna and transmits to the second subscriber station in the second subband of subcarriers from the first transmit antenna.

Abstract: A method of introducing frequency selectivity into transmissions in an orthogonal frequency division multiplexing network is provided. The method includes generating a symbol. A plurality of delayed symbols are generated based on the symbol. The delayed symbols are transmitted from multiple transmit antennas. The symbol delay values may be different for different users depending upon the users' channel characteristics.

Abstract: A scheduler for scheduling downlink transmissions of orthogonal frequency division multiple access (OFDMA) signals using spatially directed beams to a plurality of subscriber stations in a wireless network. The scheduler schedules the downlink transmissions as a function of frequency, time, and space. The scheduler further schedules downlink transmissions to a first subscriber station based on a first null space associated with at least one subscriber station previously scheduled to receive.

Abstract: A method of dynamic hybrid multiple access in a wireless network that comprises a plurality of subscriber stations is provided. The method includes selecting a sub-carrier status for each of the subscriber stations based on at least one predetermined condition for the subscriber station. The sub-carrier status is either hopping or scheduled. The predetermined condition is monitored for each subscriber station to determine whether to switch the sub-carrier status for the subscriber station based on a change in the predetermined condition.

Abstract: A hybrid beamforming apparatus and method are proposed for a communication system. The hybrid beamforming apparatus includes a plurality of antennas, a plurality of FFT, a plurality of hybrid weight-coefficient generators and a plurality of adders. In each of the hybrid weight-coefficient generators, the weight coefficient for each subcarrier is calculated by a time-domain correlation matrix and a cross-correlation vector, which is calculated by a frequency domain signal and a training signal. The hybrid beamforming apparatus and method according to the present invention can enhance immunity for multipath effect with lower system complexity.

Abstract: A base station for communicating with mobile stations in a coverage area of the wireless network. The base station comprises: 1) a transceiver for transmitting downlink OFDMA signals to each mobile station; 2) an antenna array for transmitting the downlink OFDMA signals to the mobile stations using spatially directed beams; and 3) an SDMA scheduling controller for scheduling downlink transmissions to the mobile stations. The SDMA scheduling controller determines a first mobile station having a highest priority and schedules the first mobile station for downlink transmission in a particular time-frequency slot. The SDMA scheduling controller then determines additional mobile stations that are spatially uncorrelated with the first mobile station, as well as each other, and schedules the additional mobile stations for downlink transmission in that particular time-frequency slot according to priority.

Abstract: An apparatus for generating a 2D spreading code and method for the same are proposed. The apparatus for generating the 2D spreading code includes a column counter, a row counter, a codeword selector, and a logic unit. The logic unit performs logic operations on the output of the column counter, the row counter, and the codeword selector to generate the 2D spreading code of desired order designated by the codeword selector. The 2D spreading code includes 4 2×2 initial matrixes for generating 4i codes for 4i users in the ith order. The apparatus for generating the 2D spreading code according to the present invention is advantageously used in OFDM system to increase the number of subscribers with reduced interference.

Abstract: The invention relates to an apparatus of transmitter and receiver for MIMO MC-CDMA systems. At the transmitter, modified orthogonal transmit diversity (MOTD) encoders are used for increasing space and time transmission diversity. A P-way combiner is used to connect the MOTD encoders and P multi-carrier modulators. Each modulator is connected to a set of antennas. At the receiver, each multi-carrier demodulator has an amplitude/phase compensator to compensate distortion at every sub-carrier. Similarly, a combiner is used to connect the demodulators and the MOTD decoders. Upon the invention, the space, time, and frequency diversity can be explored.

Abstract: Downlink diversity in a CDMA system is provided by employing Walsh codes in conjunction with M transmit antennas at a common base station serving K mobiles, where M may or may not be to equal to K. The present invention provides methods and apparatus for improving downlink diversity in a CDMA system. Each transmit antenna transmits a signal representing the result of the modulation of Walsh codes by data signals for each of the K mobiles, assuming there is data pertaining to a particular mobile. The assignment of Walsh codes is accomplished in accordance with a transmission matrix T. The transmission matrix maps the user data symbols onto the Walsh codes for each antenna and is preferably designed such that its columns are representative of the transmit antennas and orthogonal.

Abstract: Downlink diversity in a CDMA system is provided by employing Walsh codes in conjunction with M transmit antennas at a common base station serving K mobiles, where M may or may not be to equal to K. The present invention provides methods and apparatus for improving downlink diversity in a CDMA system. Each transmit antenna transmits a signal representing the result of the modulation of Walsh codes by data signals for each of the K mobiles, assuming there is data pertaining to a particular mobile. The assignment of Walsh codes is accomplished in accordance with a transmission matrix T. The transmission matrix maps the user data symbols onto the Walsh codes for each antenna and is preferably designed such that its columns are representative of the transmit antennas and orthogonal.