951 results about "Orthogonal frequency-division multiple access" patented technology

A method and apparatus for subcarrier selection for systems is described. In one embodiment, a method for subcarrier selection for a system employing orthogonal frequency division multiple access (OFDMA) comprises partitioning subcarriers into groups of at least one cluster of subcarriers, receiving an indication of a selection by the subscriber of one or more groups in the groups, and allocating at least one cluster in the one or more groups of clusters selected by the subcarrier for use in communication with the subscriber.

A method and apparatus for controlling OFDMA cellular networks is described. In one embodiment, the method comprises receiving channel characteristics and noise-plus-interference information measured at spatially distributed subscribers and assigning traffic channels for an orthogonal frequency-division multiple-access (OFDMA) network.

Disclosed is a method for controlling an operational state of at least one subscriber stations in an OFDM/OFDMA communication system having ranging slots and ranging codes to be used for rangings. The subscriber station performing in a Null state, an initial ranging if an initial ranging request occurs, and transitioning from the Null state to an Idle state if the initial ranging is successful; transitioning to an Access state if a bandwidth request ranging request occurs in the Idle state, and performing in the Access state the bandwidth request ranging based on a random access technique; transitioning from the Access state to a Busy state if the random access-based bandwidth request ranging is successful, performing the bandwidth request ranging based on a scheduled access technique if the bandwidth request ranging request occurs in the Busy state, and transmitting data if the scheduled access-based bandwidth request ranging is successful; and transitioning to a Hold state if the data transmission is ended in the Busy state, and performing the scheduled access-based bandwidth request ranging if the bandwidth request ranging request occurs in the Hold state.

The invention concerns a method and an apparatus implementing the method. In the method at least one synchronization signal is received from a base station to a mobile node, which determining timing based on the at least one synchronization signal, for example, a group of orthogonal frequency division multiple access resource elements. The mobile node transmits an uplink radio resource reservation request to a base station. The mobile node receives from the base station an assignment of a radio resource dedicated for radio transmission to a remote node, the radio resource being within a band having a transmission power upper limit. The mobile node transmits a signal to the remote mobile node on the radio resource based on the timing determined.

The invention discloses a joint optimization method for task unloading and resource allocation in a mobile edge computing network, which comprises the following steps of 1, establishing an OFDMA (Orthogonal Frequency Division Multiple Access)-based multi-MEC (Mobile Edge Computing) base station and a multi-user scene model, wherein the MEC base station supports the multi-user access; 2, introducing an unloading decision mechanism; Meanwhile, constructing a local calculation model and a remote calculation model, selecting a user needing to perform calculation unloading, and establishing a calculation task unloading and resource allocation scheme based on minimum energy consumption under the condition of meeting the time delay constraint according to the conditions; 3, carrying out variablefusion on three mutually constrained optimization variables, namely an unloading decision variable, a wireless resource distribution variable and a computing resource distribution variable, so as to simplify the problem; and 4, obtaining an unloading decision and a resource allocation result which enable the total energy consumption of the user in the MEC system to be minimum through a branch andbound algorithm. The method has the advantage that the energy consumption of the system can be effectively reduced on the premise that strict time delay limitation is guaranteed.

Disclosed is a method for controlling downlink power transmitted from a base station to subscriber stations in a mobile communication system employing an Orthogonal Frequency Division Multiple Access (OFDMA) scheme, in which data is carried from the base station to the subscriber stations by subchannels to each of which a plurality of subcarriers are assigned. The method includes the steps of receiving from the subscriber stations channel condition information of each of the subchannels together with information related to a subcarrier having a channel condition below a threshold from among at least one subcarrier included in each of the subchannels; calculating transmission power for each of the subchannels based on the received information; and transmitting each of the subchannels with the calculated transmission power, excluding the subcarrier having a channel condition below the threshold.

A method of wireless transmission for estimating the carrier frequency offset in a base station of a received transmission from a user equipment (UE) accessing a radio access network. The method time de-multiplexes selected symbols of a received sub-frame, computes the frequency-domain symbols received from each antenna through an FFT, de-maps the UEs selected sub-carriers for each antenna, computes metrics associated to a carrier frequency offset hypothesis spanning a searched frequency offset window, repeats these steps on subsequent received sub-frames from the UE over an estimation interval duration, non-coherently accumulates the computed metrics and selects the carrier frequency offset hypothesis with largest accumulated metric amplitude.

Methods and systems for processing communication signals in an Orthogonal Frequency Division Multiple Access (OFDMA)-Passive Optical Network (PON) are disclosed. An optical carrier at a wavelength generated at an optical line terminal (OLT) may be reused by optical network units (ONUs) in the network for upstream transmission of data signals to the OLT. In addition, each ONU may perform carrier suppression to avoid broadband beating noise resulting from the simultaneous transmission of upstream data signals on the same wavelength. Further, the optical source at the OLT used to generate the optical carrier may be reused as a local oscillator for coherent detection of received upstream signals to minimize any frequency offsets.

A method for coexistence of an orthogonal frequency division multiple access (OFDMA) receiver (117) such as a WiMAX receiver with a synchronous frame-based transmitter (115) such as a Bluetooth transmitter within a mobile station (110) receives an estimated media access protocol (MAP′) signal indicating when a MAP message is expected to be received by the OFDMA receiver (117) and uses it at a Bluetooth shutdown signal (190) at least when a MAP message is expected to be received. The MAP′ signal can be taken directly from the ODFMA transceiver (117) or it may be produced through analysis of a receiver-enable (RXE) signal that includes not only MAP symbols but also downlink data symbols. The RXE signal can be analyzed using interrupt-and-timer, Fast Fourier Transform, covariance, and/or delay-locked loop techniques to extract historical MAP symbol information and generate expected MAP symbol information. Shutting down a Bluetooth transmitter during expected MAP message receipt permits the OFDMA receiver to maintain synchronicity with an access point while not requiring the Bluetooth transmitter to shut down every time the OFDMA receiver expects to receive an OFDMA symbol.

A relay communication method in an orthogonal frequency division multiple access (OFDMA) communication system including at least one base station for providing a multiple access service to a plurality of mobile stations frame by frame. The relay communication method includes dividing a cell defined by transmission power of the base station into a plurality of sectors on the basis of the base station; dividing the cell into an inner area where a first service is supported and an outer area where a second service is supported, on the basis of the base station; arranging at least one relay station in a second service area of each sector; and allocating a partial resource of the frame for communication between the base station and the mobile station through the relay station.

A method and apparatus for transmitting uplink acknowledge information (ACK) in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme. The method includes receiving a data bit for the uplink ACK; outputting codewords corresponding to the data bit; performing quadrature phase shift keying (QPSK) modulation on symbols for ACK vector indexes corresponding to the codewords for the received data bit; performing inverse fast Fourier transform (IFFT) on a transmission signal having subcarrier clusters to which the modulated transmission symbols are allocated; and transmitting the IFFT-processed transmission signal.

The present invention centers upon uplink communication protocols for use primarily with orthogonal frequency division multiple access (OFDMA) communication systems. Aspects of the invention relate to narrow band frequency division multiplexed (NBFDM) modulation protocols primarily for uplink usage in asymmetric OFDMA communication systems. In particular, NBFDM uplinks that use quadrature multiplexed continuous phase modulation are detailed and noncoherent detection schemes are developed to process the uplink channel signals without the need to transmit uplink phase reference signals. Other aspects of the invention relate to burst mode uplink communications in OFDMA systems such as those involving opportunistic beamforming.

The invention discloses a communication method and wireless communication system for realizing multi-user dispatching. The method comprises the following steps: refining and multiplexing are carried out on physical resources in the wireless communication system so that multiple users can simultaneously access the physical resources in parallel; downlink transmission is carried out based on orthogonal frequency division multiple access (OFDMA) and multi-user-multiple-input and multiple-output (MU-MIMO) mechanism, and uplink transmission is carried out based on OFDMA or OFDMA+time division multiple access (OFMA+TDMA); an access point sends a multi-user polling frame or channel detection frame which carries an uplink transmission resource indication; a user station transmits data and feeds back channel status information according to the resource indication; and the system selects a user group for downlink data transmission and sends data to the users in the user group. According to the invention, a media access control (MAC) layer dispatching mechanism allowing multiple users to access simultaneously is achieved, and uplink and downlink services are comprehensively considered to realize two-way communication in the wireless communication system, thus the access delay can be obviously reduced, the system throughput can be obviously improved, and the requirement of accessing more multi-media services can be met.

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.

A method for transmitting uplink control information in a communication system using an orthogonal frequency division multiple access (OFDMA) scheme is provided. A mobile station (MS) selects a target anchor base station (BS) with which the MS desires to communicate through a fast feedback channel, and transmits a codeword allocated to the selected target anchor BS to a current anchor BS. Upon receiving the codeword, transmitting to the MS, by the anchor BS, fast feedback channel allocation information for the selected BS corresponding to the received codeword. The MS switches to a new anchor BS corresponding to the fast feedback channel allocation information.

A method and apparatus for subcarrier selection for systems is described. In one embodiment, a method for subcarrier selection for a system employing orthogonal frequency division multiple access (OFDMA) comprises partitioning subcarriers into groups of at least one cluster of subcarriers, receiving an indication of a selection by the subscriber of one or more groups in the groups, and allocating at least one cluster in the one or more groups of clusters selected by the subcarrier for use in communication with the subscriber.

A method is provided for transmitting a control channel for resource allocation to a terminal by a base station in an Orthogonal Frequency Division Multiple Access (OFDMA) wireless communication system. An additional resource allocation indicator is set indicating whether the number of consecutive resource block sets allocated to a terminal is greater than one. A reference control channel is generated including reference resource allocation information for a first consecutive resource block set and the set additional resource allocation indicator. An additional control channel using additional resource allocation information is generated, when there are one or more additional consecutive resource block sets. At least one of the generated reference control channel and the generated additional control channels is encoded before transmission.

A method for allocating a frequency to a subscriber station (SS) in handover operation in an Orthogonal Frequency Division Multiple Access (OFDMA) system. In the method, the SS checks safety channel frequencies for a target base station (BS), generates a safety channel frequency request message for requesting allocation of the checked safety channel frequencies, and transmits the safety channel frequency request message. Upon receiving the safety channel frequency request message from the SS, a serving BS allocates frequencies for a requested channel, and transmits an allocation message with the frequency allocation information to the SS. The serving BS transmits a channel allocation request message to the target BS according to the frequency allocation information. Upon receiving the channel allocation request message, the target BS allocates the safety channel frequencies to the SS.

A system and method for synchronous spectrum sharing for a dedicated network in a wireless communication system based on orthogonal frequency-division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) signaling is disclosed. The system and method includes detecting a frame of a broadcast waveform and extracting idle spectrum information associated with the dedicated subchannel to the secondary user node. The system allows transmitting data from the secondary user node in unused symbol slots identified in the idle spectrum information thereby making efficient use of unused or idle spectrum. Accordingly, secondary users of the wireless communication system can dynamically form ad-hoc mesh network communications in fixed or mobile scenarios.

A station is disclosed that is configured for signal transmission in an Orthogonal Frequency Division Multiple Access (OFDMA) system. The station includes a processor configured to fix a subcarrier spacing to a predetermined value for one or more subframes in all available bandwidths. The station further includes a transmitter configured to transmit a signal having the fixed subcarrier spacing, regardless of a frame structure of the one or more subframes. According to certain embodiments, the predetermined value may be divided evenly by at least one channel raster. The predetermined value may be 12.5 KHz, according to certain embodiments. Alternatively, the predetermined value is 6.25 KHz for one or more low mobility mobile stations, and/or the predetermined value is 25 KHz for one or more high mobility mobile stations. The station may be a mobile station or a base station configured for uplink and downlink transmission.

Dynamic resource allocation systems, apparatus, and methods are disclosed for selectively improving the ability of a receiver to determine a channel estimate in an Orthogonal Frequency Division Multiple Access (OFDMA) system. A wireless communication system can use a common pilot channel configuration to aid channel estimation in one or more receivers in communication with the system. A receiver in communication with the system may be unable to demodulate received data due to an inaccurate channel estimate. The receiver can communicate to a transmitter in the system a request for additional channel estimation resources. The wireless communication system can provide additional channel estimation resources by inserting dedicated pilot channels into one or more of the frequencies allocated to symbols for the receiver. If the receiver is still unable to demodulate received data, the wireless communication system can incrementally insert additional pilot channels in the symbol associated with the receiver.

A shared signaling channel can be used in an Orthogonal Frequency Division Multiple Access (OFDMA) communication system to provide signaling, acknowledgement, and power control messages to access terminals within the system. The shared signaling channel can be assigned to a predetermined number of sub-carriers within any frame. The assignment of a predetermined number of sub-carriers to the shared signaling channel establishes a fixed bandwidth overhead for the channel. The actual sub-carriers assigned to the channel can be varied periodically, and can vary according to a predetermined frequency hopping schedule. The amount of signal power allocated to the signaling channel can vary on a per symbol basis depending on the power requirements of the communication link. The shared signaling channel can direct each message carried on the channel to one or more access terminals. Unicast messages allow the channel power to be controlled per the needs of individual communication links.

A shared signaling channel can be used in an Orthogonal Frequency Division Multiple Access (OFDMA) communication system to provide signaling, acknowledgement, and power control messages to access terminals within the system. The shared signaling channel may comprise reserved logical resources that can be assigned to subcarriers, OFDM symbols, or combinations thereof.