2132 results about "Orthogonal frequency-division multiplexing" patented technology

The distortion in the sub-carrier signals is determined by transmitting known values that are incorporated into the preamble portion of the frame and/or are incorporated into pilot symbols that are inserted into the data portion of the frame. The receiver typically receives these known values in a distorted form and then processes the distorted values together with the original known values to obtain a channel response. The channel response is then used to estimate the frequencies at which the channels are received.

Methods and systems are provided for allocating resources including VoIP (voice over Internet Protocol) and Non-VoIP resources. In some embodiments, multiplexing schemes are provided for use with OFDMA (orthogonal frequency division multiplexing access) systems, for example for use in transmitting VoIP traffic, in some embodiments, various HARQ (Hybrid Automatic request) techniques are provided for use with OFDMA systems. In various embodiments, there are provided methods and systems for dealing with issuea such as Handling non-full rate vocoder frames, VoIP packet jitter handling, VoIP capacity increasing schemes, persistent and non-persistent assignment of resources in OFDMA systems.

A wireless communication includes a base station that configures a set of non-zero power reference signals corresponding to multiple potential transmission points to one or more users equipment UEs and configures at least one zero-power reference signal, with zero transmission power from one or more of the multiple transmission points. The base station transmits configuration information to at least one UE of the one more UEs, wherein the configuration information corresponds to a set of resource elements that are associated with a set of channel state information reference signals and wherein the set of channel state information reference signals include the set of nonzero-power reference signals and the at least one zero-power reference signal. The UE then performs a channel measurement based on one or more non-zero-power reference signals of the set of non-zero-power reference signals and performs an interference measurement based on the at least one zero-power reference signal.

The present invention provides an FM Orthogonal Frequency Division Multiplexing (OFDM) modulation process that enable high-speed data communications over any transmission media and networks. The process is implemented with a modem device modulator and demodulator that provides communication with several other modem devices along any communication media that uses an FM OFDM modulation technique, a physical transmission medium such as power lines, or wireless (air), or cable, or twisted pairs communication media.

In a communications system which complies with LTE including a base station 2 which transmits data by using an OFDM (Orthogonal Frequency Division Multiplexing) method as a downlink access method, and a mobile terminal 3, in a case in which an uplink scheduling request signal SR is transmitted by using an S-RACH when an Ack/Nack signal is being transmitted by using an Ack/Nack exclusive channel, the transmission of the Ack/Nack signal is stopped while the uplink scheduling request signal SR is transmitted.

The embodiment of the invention provides a method and base station for transmitting and receiving signals by using unauthorized carrier waves and user equipment. The method includes the steps that the base station transmits unauthorized carrier wave information to the user equipment (UE) through authorized carrier waves; after obtaining the use right to the unauthorized carrier waves through competition in a competition backspacing window, the base station uses residual resources and/or subframes behind the residual resources in the competition backspacing window for transmitting the signals to the UE, and the residual resources comprise complete orthogonal frequency-division multiplexing (OFDM) symbols after the moment point of obtaining the use right of the unauthorized carrier waves through competition and located in the competition backspacing window, or complete PFDM symbols between the moment point of obtaining the use right of the unauthorized carrier waves for the base station through competition and the moment when the subframe where the moment point is located is finished.

A communications apparatus is provided. A first radio module provides a first wireless communications service and communicates with a first communications device in compliance with a first protocol. A second radio module provides a second wireless communications service and communicates with a second communications device in compliance with a second protocol. A Co-Located Coexistence radio manager detects activities of the first radio modules, obtains a first traffic pattern describing downlink and/or uplink traffic allocations of the first radio module from the first radio module, and generates a second traffic pattern of the second radio module according to the first traffic pattern to coordinate operations of the first and second radio modules. The second traffic pattern describes recommended downlink and/or uplink traffic allocations to a plurality of sub-frames for the second radio module, and each sub-frame defined by the second protocol includes Orthogonal Frequency Division Multiplexing symbols.

One or more preambles are inserted into frames of Orthogonal Frequency Multiplexing (OFDM)-Multiple Input, Multiple Output (MIMO) signals. The preamble is received by the antennas of a receiver, decoded and compared to known values to provide synchronization, framing, channels estimation, offsets and other corrections to the transmitted signal.

A virtual cell management apparatus and method using sectors in an orthogonal frequency division multiplexing mobile communication system including a cell structure having cells each comprised of a plurality of sectors, the cells performing data communication with mobile terminals within a corresponding cell through at least one subchannel having orthogonality. The method comprises forming a virtual cell with a particular one of sectors constituting a particular cell and sectors of two other cells neighboring the particular sector; transmitting, by three base stations forming the virtual cell, an interference measurement value and a channel parameter estimation value from a mobile terminal located in the virtual cell to a base station controller that controls the virtual cell, thereby allocating wireless resource including frequency bandwidth, initial bits, subcarriers and refined bits in the virtual cell; transmitting the allocated wireless resource to the three base stations so that the base stations allocate a same subchannel to each mobile terminal located in the virtual cell; and transmitting same data over the allocated subchannel.

An apparatus and method for transmitting/receiving an random access channel (RACH) signal in a broadband wireless communication system where a total uplink frequency band is divided into M sub-bands are provided. In the RACH transmitting apparatus, a generator generates an access code. A sub-carrier allocator divides the access code into M sub-blocks and allocates each of the M sub-blocks to successive sub-carriers in a sub-band. An inverse fast Fourier transform (IFFT) processor generates an orthogonal frequency division multiplexing (OFDM) symbol by performing an IFFT on the allocated sub-blocks.

A closed loop feedback system is employed in a receiver to automatically compensate the communication signal from twisted pair cables for AC and DC losses. This is accomplished through the use of a reference pulse signal which is sent along with other digital information. At the receiver, the reference pulse signal is restored to its proper level through a Pulse Width Modulation (PWM)-controlled variable compensation amplifier circuit. The received reference signal is compared to a known reference value and the duty cycle of the PWM circuit is adjusted until the proper level reference signal is achieved. Thereafter, the digital signal is extracted. OFDM (Orthogonal Frequency Division Multiplexing) with pilot tones are used to maximize payload while minimizing crosstalk effects. The pilot tones locate the OFDM symbols in time while supplying compensation information concerning the transmission medium.

Methods in a wireless terminal are described for supporting co-ordinated multipoint transmissions including joint transmissions from two or more transmission points, specifically the method of receiving indication of two or more CSI reference signal configurations, each CSI reference signal configuration representing one or more antenna ports comprising a set of antenna ports; determining a first set of transmission parameters corresponding to a first set of antenna ports corresponding to a first CSI reference signal configuration and a second set of transmission parameters corresponding to a second set of antenna ports corresponding to a second CSI reference signal configuration; the first set and second set of transmission parameters determined to maximize the sum data rate for simultaneous transmission from the first set and the second set of antenna ports; conveying, to the base station, information pertaining to the first set of transmission parameters and the second set of transmission parameters.

An orthogonal frequency division multiplexing (OFDM) transmitter method, consistent with certain embodiments of the present invention arranges OFDM data symbols representing data bits for transmission in a packet. A prescribed pattern of OFDM data symbols are removed (212) and replaced (216) with pilot symbols. The packet is then transmitted (220) to an OFDM receiver that receives the packet (224) and determines a channel correction factor from the pilot pattern. The receiver then estimates a plurality of channel correction factors, one for each of the plurality of OFDM symbols representing data (228) and uses these correction factors to correct the OFDM symbols representing data (232). Arbitrary data are then inserted in place of the pilot symbols (236). The OFDM symbols representing data along with the arbitrary data are then decoded using an error correction decoder that corrects the errors induced by substitution of the pilot symbols for data symbols (240).

An orthogonal wavelet division multiplexing (OWDM) communication system including a synthesis section and a channel interface. The synthesis section includes a filter pair bank with multiple inputs and an output that provides an OWDM signal. Each input receives a corresponding symbol of a supersymbol, where the symbols are from a selected modulation scheme. The synthesis section generates the OWDM signal as a combination of weighted OWDM pulses, where each weighted OWDM pulse represents of a symbol of the supersymbol. An OWDM Spread Spectrum (OWSS) communication system that uses broad-time and broadband pulses generated from a family of OWDM pulses together with a set of orthogonal PN code vectors. The OWSS pulses are mutually orthogonal and allow multi-user operation. Each user is assigned an OWSS pulse corresponding to a particular PN code. OWSS enables high rate operation for wireless channels with the use of an equalizer with FE and DFE sections.

Base station identification and downlink synchronization are realized by employing pilots including known symbols transmitted at prescribed frequency tones in individual ones of prescribed time intervals. Specifically, the symbols used in the pilots are uniquely located in a time-frequency grid, where the locations are specified by periodic pilot tone hopping sequences. In a specific embodiment of the invention, a period of a pilot tone hopping sequence is constructed by starting with a Latin-square based hopping sequence, truncating it over time, and possibly offsetting and permuting it over frequency. Particular examples of pilot tone hopping sequences are parallel slope hopping sequences in which the periodicity of the sequences is chosen to be a prime number of symbol time intervals. In another embodiment of the invention, a notion of phantom pilots is employed to facilitate use of various system parameters while accommodating the above noted pilot tone hopping sequences.

By virtue of one embodiment of the present invention, dynamic signal to noise ratio measurements made on received signals are used to identify degraded segments of a channel. The degraded segments are then no longer used for transmitting payload data. In the context of an orthogonal frequency division multiplexing (OFDM) communication system, degraded OFDM subchannels, as determined on a real-time basis, are not used to transmit payload data. In an OFDM network where access is shared in the time domain among multiple transmitters and a single allocable time slot includes an integer number of OFDM bursts, the medium access control layer adjusts packet length, and therefore the amount of data to be included in a given slot, in response to the fluctuating number of available subchannels.

A fixed wireless system (FWS) utilizing Orthogonal Frequency Division Multiplexing (OFDM) communication techniques is spectrally efficient and responsive to communications involving both voice and high speed data, such as Internet data. The FWS includes a wireless base unit; a plurality of fixed wireless remote units; a plurality of wireless data traffic channels available between the wireless base unit and the plurality of fixed wireless remote units; and a plurality of wireless voice traffic channels available between the wireless base unit and the plurality of fixed wireless remote units. Each wireless traffic channel is identifiable by a unique combination of frequency and time slots. Each wireless data traffic channel is used for carrying high speed data in addressed data packets to and from the plurality of fixed wireless remote units. On the other hand, each wireless voice traffic channel can be assigned and dedicated to a particular voice communication call involving one of the plurality of fixed wireless remote units for carrying voice data of the call.

A resource division, allocation, and transmitting/receiving method of downlink for reducing inter-cell interference in an orthogonal frequency division multiplexing system are provided. Entire downlink radio resources are divided into a traffic resource group for a traffic channel and a control resource group for a control channel, the traffic resource group is divided into a first traffic resource group for the intra-cell mobile terminals and a second traffic resource group for a cell-boundary mobile terminal, and a part of the first traffic resource group is imaginarily divided into a (1−1)-th preliminary traffic resource group, the (1−1)-th preliminary traffic resource group being a preliminary resource group for the cell-boundary mobile terminal. The control resource group is allocated to a control channel for the intra-cell mobile terminal; and a resource of the first traffic resource group or the second traffic resource group is allocated to a traffic channel for the mobile terminal according to inter-cell interference affected to the mobile terminal. Radio resources may be reused in each downlink cell of the OFDM system, the traffic may be rapidly transmitted to the cell boundary mobile terminal, a system capacity may be increased, the cell plane may be easily performed, and the system capacity may not be decreased although the mobile terminal number, locations, and traffic density is not uniform.

A method of allocating resource elements in an orthogonal frequency division multiplexing (OFDM) system for transmission of a channel state information reference signal (CSI-RS) is disclosed. The method includes converting resource elements to a two-dimensional frequency-time domain. The converted resource elements can then be partitioned to units of a physical resource block (PRB), which can be one subframe, for example. It can be determined whether a portion of a PRB is being used by another signal; and if the portion of the PRB is not being used, it can be allocated for transmission of the CSI-RS. The CSI-RS can be transmitted at resource element locations determined by the resource elements available to the CSI-RS in a regular or a frequency-division duplexing (FDD) downlink subframe, for example. The CSI-RS can be transmitted in a downlink subframe configured as a Multi-Media Broadcast over a Single Frequency Network (MBSFN) or a non-MBSFN subframe.

An apparatus and method for communication using sound waves is disclosed. More particularly, orthogonal frequency division multiplexing scheme is used to transmit and receive digital data on sound waves. In one embodiment, the sound waves are used to exchange information. In another aspect, the sound waves are used to authenticate an individual or device.