1284 results about "Orthogonal frequency code division multiplexing" patented technology

An uplink capacity is increased by a method in which more than two mobile stations simultaneously use a radio resource allocated to one mobile station. A method of allocating a radio resource in an orthogonal frequency division multiplexing system comprises receiving data associated with a radio resource allocation map from a base station, wherein the radio allocation map comprises control parameters for transmitting uplink data to the base station. The control parameters comprises orthogonal pilot pattern indicator for using orthogonal pilot patterns associated with supporting at least concurrent dual transmission by at least one mobile station, and for use in the same frequency band and same time duration. The orthogonal pilot patterns comprises at least a minus pilot being used for an uplink basic allocation unit. The mobile station then transmits uplink data to the base station by using the orthogonal pilot patterns.

A method of transmitting/receiving channel quality information (CQI) of subcarriers in an OFDM system where data is transmitted on the subcarriers via one or more transmit antennas. The subcarriers are grouped into subcarrier groups each having at least one subcarrier and further grouped into subgroups each having one or more subgroups. A user equipment generates CQIs for one or more allocated subcarrier groups and the transmit antennas or CQIs for the allocated subcarrier groups, the subgroups of the subcarrier groups, and the transmit antennas. The group CQIs and the subgroup CQIs are transmitted to a Node B in one or more physical channel frames.

A method for transmitting channel quality information (CQI) from a receiver station to a transmitter station in a wireless communication system which includes diversity mode consisted of spaced apart subcarriers and band AMC mode consisted of a number of bands comprised of a predetermined number of adjacent subcarriers. The method comprises the steps of transmitting an average CINR(Carrier to Interference and Noise Ratio) value for a full frequency band if the receiver station operates in the diversity mode; transmitting a differential CINR of a predetermined number of bins if the receiver station operates in the band AMC mode.

The soft handoff in an OFDMA system. If the pilot signal strength for a base station exceeds the defined threshold, the base station is added to an active set list. Subcarriers in a plurality of orthogonal frequency division multiplexing (OFDM) symbols are divided and allocated into subchannels. The OFDM symbols are divided and multiplexed. A soft handoff zone with a first dimension of the subchannels and a second dimension of the divided and multiplexed OFDM symbols is defined. The soft handoff zone have subcarriers with a subchannel definition, for example, an identical permutation.

An apparatus and method for allocating a frequency resource to a user equipment (UE) in an orthogonal frequency division multiplexing (OFDM) mobile communication system. A base station receives feedback information including at least mobility information from the UE, and determines from the mobility information whether the UE belongs to a fast group or a slow group. The base station allocates a frequency resource for the UE according to an open-loop solution if the UE belongs to the fast group, allocates a frequency resource for the UE according to a closed-loop solution if the UE belongs to the slow group, and transmits data for the UE using the allocated frequency resource.

A method and apparatus for efficiently transmitting channel quality information in an OFDM communication system using dynamic channel allocation and adaptive modulation, and determining parameters required for time-division channel quality information transmission in an asynchronous CDMA communication system are provided. In the OFDM communication system in which a plurality of subcarriers are allocated to a plurality of UEs, the subcarriers are divided into a plurality of subcarrier groups each having at least one subcarrier. Each of the UEs determines and transmits the channel quality information of each of the subcarrier groups according to predetermined transmission parameters at transmission time points that do not overlap with those of other UEs. A Node B dynamically allocates the subcarriers to the UEs and their corresponding modulation schemes according to the channel quality information.

A method is provided for allocating resources of a control channel in a mobile communication system using Orthogonal Frequency Division Multiplexing (OFDM). The method includes, when a time index and a frequency index of available Resource Elements (REs) are defined as l and k, respectively, dividing the available REs in a two-dimensional structure of (k, l); and time-first-allocating each RE to a plurality of RE groups while increasing the time index l for each frequency index k from an initial value up to a predetermined range.

A mobile communication system and method utilizing Orthogonal Frequency Division Multiplexing (OFDM) receives channel quality information (CQIs) for subcarriers through which reference signals are transmitted and subcarriers through which data signals are transmitted, in subbands, each including a predetermined number of subcarriers among a plurality of the subcarriers. The CQIs are fed back from respective receivers. Resources are dynamically assigned to the respective receivers according to the feedback CQIs, thereby enabling dynamic resource assignment with minimized signaling overhead.

In an OFDMA mobile communication system in which a total frequency band is divided into a plurality of sub-carrier bands, for signal transmission, to assign sub-carriers to MSs, a BS divides the total frequency band into L sub-frequency bands. The BS detects the channel condition of each of the MSs and determines a sub-frequency band for each MS according to the channel condition among the L sub-frequency bands. The BS assigns sub-carriers in the determined sub-frequency band at a predetermined sub-carrier spacing to each MS.

A method and apparatus for protecting and authenticating wirelessly transmitted digital information using numerous techniques. The apparatus may be a wireless orthogonal frequency division multiplexing (OFDM) communication system, a base station, a wireless transmit/receive unit (WTRU), a transmitter, a receiver and/or an integrated circuit (IC). The wireless OFDM communication system includes a transmitter which steganographically embeds digital information in an OFDM communication signal and wirelessly transmits the OFDM communication signal. The system further includes a receiver which receives the OFDM communication signal and extracts the steganographically embedded digital information from the received OFDM communication signal.

An apparatus and method for assigning sub-carriers in an orthogonal frequency division multiplex (OFDM) system are disclosed. In the apparatus and method, data is transmitted through at least one transmit antenna. At least two sub-carriers in a predetermined frequency band are assigned to a user equipment (UE), for data transmission. A Node B groups sub-carriers available to the OFDM system into sub-carrier groups, each having at least two sub-carriers, transmits data to the UE on sub-carriers in the sub-carrier groups, selects at least one sub-carrier group for the UE based on channel condition information about each of the sub-carrier groups received from the UE, and assigns the selected sub-carrier group to the UE.

A power line communication device for communicating data signals over a power line is provided. One example embodiment comprises a conditioning circuit configured to be coupled to the power line and a modem communicatively coupled to the conditioning circuitry to transmit and receive data signals over the power line via the conditioning circuitry. The modem may be configured to transmit and receive orthogonal frequency division multiplexed data signals that comprise a plurality of sub-carriers, wherein the modem is adapted to vary the transmit power for each of a plurality of subsets of the plurality of sub-carriers from substantially zero power to a plurality of increments above zero power. The modem also may be adapted to transmit and receive data signals with the transmit power for each of a plurality of subsets of the plurality of sub-carriers being different and to transmit and receive using a different modulation scheme at different sub-carriers.

Provided are a sync channel of a forward link, a common pilot channel structure, and an initial cell search method and an adjacent cell search method for handover in a cellular system using orthogonal frequency division multiplexing (OFDM). A cell search method in an OFDM cellular system in which a primary sync channel and a secondary sync channel are configured based on time division multiplexing (TDM) includes acquiring sync block synchronization and a primary sync channel sequence number using a primary sync channel symbol included in a frame received by a terminal, detecting a boundary of the frame and a scrambling code group using the sync block and a secondary sync channel symbol included in the frame received by the terminal, and acquiring a scrambling code using the primary sync channel sequence number and the scrambling code group, thereby reducing cell search time with low complexity.

An approach is provided for supporting transmission in a multi-input-multi-output (MIMO) communication system including a plurality of terminals. A preamble portion of a frame is transmitted by a multiple transmit antennas of a hub using Orthogonal Frequency Division Multiplexing (OFDM) to the terminals over a channel, wherein each of the terminals determines a characteristic of the channel with respect to the transmit antennas as feedback information. The hub receives the feedback information from the terminals. The hub selects, according to the feedback information, a subset of the antennas for transmission of a remaining portion of the frame to the terminal.

A system for compensating for in-phase and quadrature (I/Q) imbalances for multiple antenna systems (MAS) with multi-user (MU) transmissions (defined with the acronym MU-MAS), such as distributed-input distributed-output (DIDO) communication systems, comprising multicarrier modulation, such as orthogonal frequency division multiplexing (OFDM). For example, one embodiment of the system comprises one or more coding modulation units to encode and modulate information bits for each of a plurality of wireless client devices to produce encoded and modulated information bits; one or more mapping units to map the encoded and modulated information bits to complex symbols; and a MU-MAS or DIDO IQ-aware precoding unit to exploit channel state information obtained through feedback from the wireless client devices to compute MU-MAS or DIDO IQ-aware precoding weights, the MU-MAS or DIDO IQ-aware preceding unit precoding the complex symbols obtained from the mapping units using the weights to pre-cancel interference due to I/Q gain and phase imbalances and/or inter-user interference.

A mobile communication system using an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) scheme. The method for assigning ranging codes in the OFDM/OFDMA communication system includes classifying rangings between a base station and a mobile subscriber station (MSS) of the OFDM/OFDMA communication system into an initial ranging, a periodic ranging, a bandwidth request ranging, and a handover ranging. A first number of ranging codes used for the rangings are created and a second number of ranging codes selected from the first number of ranging codes are assigned as handover ranging codes used for the handover ranging.

Multiple Transmit Multiple Receive Orthogonal Frequency Division Multiplexing (‘OFDM’) comprising generating bit streams and corresponding sets of N frequency domain carrier amplitudes ({tilde over (s)}(kN+j), 0≦j≦N−1) modulated as OFDM symbols subsequently to be transmitted from a transmitter, where k is the OFDM symbol number and j indicates the corresponding OFDM carrier number. Affix information is inserted at the transmitter into guard intervals between consecutive time domain OFDM symbols and are used at the receiver to estimate the Channel Impulse Response (H_lm) of the transmission channels, the estimated Channel Impulse Response (Ĥ_lm) being used to demodulate the bit streams in the signals received at the receiver. The affix information is known to the receiver, as well as to the transmitter, and is mathematically equivalent to a vector (c_D) that is common to the time domain OFDM symbols multiplied by at least first weighting factors (α_k) that are different for one time domain OFDM symbol (k) than for another and second weighting factors (w_i(k)) that enable one of the transmit antenna means (i) to be distinguished from another.

An apparatus and a method for cell search in an orthogonal frequency division multiplexing-based mobile communication system using a multiple access scheme. The method includes the steps of: detecting a symbol boundary of an input reception signal; detecting a frame cell boundary after synchronizing with the detected symbol boundary; detecting a reference signal for each symbol interval in a preset search interval; and detecting a pattern of the detected reference signals and detecting a base station to which the terminal belongs.

An apparatus and a method for reducing an error vector magnitude in an orthogonal frequency division multiplexing (OFDM) receiver. The method includes the steps of inputting a receiving symbol including a guard interval and an effective symbol interval following the guard interval, in which a front portion of the guard interval and a rear portion of the effective symbol interval have windowing intervals corresponding to windowing of a transmitter, and replacing a signal of the rear windowing interval with a signal of an interval between the front windowing interval and the effective symbol interval, thereby outputting a signal of the effective symbol interval, which substitutes for a signal of the rear windowing interval, to a fast Fourier transform (FFT) section.