96 results about "Cyclic delay diversity" patented technology

In this invention, several open-loop solutions that encompass the small delay CDD codeword cycling, codeword cycling between different re-transmissions of both small and large delay CDD are proposed. In addition, an open-loop codeword cycling method for SFBC+FSTD scheme, as well as its extension to SFBC+FSTD based HARQ, are proposed. In one method, a plurality of information bits are encoded, scrambled and modulated to generate a plurality of modulation symbols. The plurality of modulation symbols are mapped onto the subcarriers in at least one transmission layer of a transmission resource. The modulation symbols are then precoded by using a matrix for cyclic delay diversity and a set of codewords from a certain codebook to generate a plurality of precoded symbols. The codewords are cycled for every a certain number of subcarriers. Finally, the precoded symbols are transmitted via a plurality of transmission antennas.

A frame timing synchronization technique for orthogonal frequency division multiplexing (OFDM) systems is presented. First, a coarse synchronization technique generates a coarse frame timing estimate. The coarse synchronization technique applies a sliding window differentiator to the output of a conventional auto-correlator to mitigate the plateau effect associated with conventional auto-correlation techniques. Second, a fine synchronization technique generates a fine frame timing estimate. The fine synchronization technique uses the coarse frame timing estimate to reduce the number of cross-correlation calculations. Additionally, the fine synchronization technique acquires a fine frame timing estimate based on a signal-to-interference ratio (SIR) metric, which is more robust to multi-paths and pseudo multi-paths caused by cyclic delay diversity (CDD) schemes than conventional cross-correlation synchronization techniques. A fine-tuning technique generates a desired frame timing estimate by searching a first signal path in a searching window around the fine frame timing estimate to further refine frame timing synchronization.

A base station for use in a wireless network communicating with a plurality of subscriber stations. The base station transmits in a downlink channel to a first subscriber station using a plurality of transmit antennas. The base station transmits to the first subscriber station using either a transmit diversity scheme or a beamforming scheme according to the amount of correlation between the transmit antennas observed at the first subscriber station. The base station also transmits to the first subscriber station using a cyclic delay diversity scheme having either zero delay or non-zero delay according to the amount of antenna / channel correlation observed at the first subscriber station.

A diversity transmitter for use in an OFDM transmission protocol which diversity transmitter comprises:a diversity generator (2) for receiving and diversifying OFDM transmit symbols, and outputting diversified OFDM symbol matrices (DOSM), DOSM symbols within each DOSM being divided into at least two primary streams each comprising different DOSM symbols,a transmit processor for receiving said at least two primary streams of DOSM symbols, and for transforming said each DOSM symbol from the frequency domain into the time domain, and outputting time domain OFDM symbols (TDOSs),a cyclic delay circuit (41 . . . 4P) for dividing at least one of said primary streams of TDOSs into at least two branches of identical TDOSs, each branch for supplying a respective spatial channel for transmission to a receiver,the arrangement being such that, in use, said cyclic delay circuit (41 . . . 4P) applies a cyclic time shift to a TDOS symbol in at least one of said branches before transmission.

An apparatus and method for Time-Varying Cyclic Delay Diversity (TV-CDD) in a wireless communication system are provided. The method includes, if there is a signal of an antenna path to be transmitted, determining if a current time corresponds to a preamble zone within a frame and, if the current time corresponds to the preamble zone within the frame, shifting a partial antenna path signal forward compared to a reference timing and shifting a remaining partial antenna path signal equally or backward compared to the reference timing.

The present invention provides an apparatus and method for efficient guaranteed transmission variation for the same broadcast signal transmitted from at least two base stations (BS). A radio network controller (RNC) considers a radio channel state of a mobile station (MS), and transmits information to a plurality of BSs located in a cell configured by three sectors for performing mutation. Each BS is equipped with at least two transmit antennas. According to this information, the BS in the cell performs space-time block coding on the data to be transmitted, applies different periodic delays to the data, and transmits the data to the MS through at least two transmit antennas.

A method and an apparatus for implementing spatial processing with unequal modulation and coding schemes (MCSs) or stream-dependent MCSs are disclosed. Input data may be parsed into a plurality of data streams, and spatial processing is performed on the data streams to generate a plurality of spatial streams. An MCS for each data stream is selected independently. The spatial streams are transmitted via multiple transmit antennas. At least one of the techniques of space time block coding (STBC), space frequency block coding (SFBC), quasi-orthogonal Alamouti coding, time reversed space time block coding, linear spatial processing and cyclic delay diversity (CDD) may be performed on the data / spatial streams. An antennal mapping matrix may then be applied to the spatial streams. The spatial streams are transmitted via multiple transmit antennas. The MCS for each data stream may be determined based on a signal-to-noise ratio of each spatial stream associated with the data stream.

A gap filler apparatus providing cyclic delay diversity in a digital multimedia broadcasting (DMB) system. In the gap filler apparatus, a receiver receives an orthogonal frequency division multiplexing (OFDM) signal transmitted as a broadcasting signal. A symbol synchronization unit acquires symbol synchronization of the OFDM signal, detects a guard interval of an OFDM symbol using the symbol synchronization, determines a sample length, by which the OFDM symbol is cyclic-delayed within the guard interval, and cyclic-delays the OFDM signal by the determined sample length. An amplifier amplifies the cyclic-delayed OFDM signal. A transmitter transmits the amplified OFDM signal to a wireless network.

In a radio network a determination is made whether to implement cyclical delay diversity (CDD) for a radio frequency connection involving a radio base station (26) and a wireless terminal (30). The determination whether to implement cyclical delay diversity (CDD) is made in accordance with interference distribution at the wireless terminal (30), as such interference distribution is measured or otherwise perceived. When a determination is made to implement the cyclical delay diversity for the connection, plural transmit antennas (38) of the radio base station (26) are employed to implement the cyclical delay diversity for the connection. One or more indications of the interference distribution may be received and used to make the determination. The indication(s) of interference distribution can take the form of information received from the wireless terminal, and / or the form of frequency reuse plan information for interfering cells. For example, the determination to implement the cyclical delay diversity can be made affirmatively if the frequency reuse for interfering cells is above a predetermined frequency reuse number. In differing embodiments, either the radio base station (26) or the wireless terminal (30) can make the CDD implementation determination.

In a method of transmitting a data stream from a transmitter in a multiple-input-multiple-output (MIMO) wireless communication system, where the transmitter comprises a plurality of transmit antennas, a discrete Fourier transform (DFT) is applied to the data stream to generate a plurality of symbol sequences; symbols of a first symbol sequence from the plurality of symbol sequences are paired with symbols of a second symbol sequence from the plurality of symbol sequences to generate a plurality of symbol pairs, wherein the pairing results in an orphan symbol; a space-time block code (STBC) is applied to the symbol pairs to generate a plurality of sets of STBC symbols, each set of STBC symbols being associated with a corresponding one of the plurality of antennas; a cyclic delay diversity (CDD) operation is applied to the orphan symbol to generate a plurality of CDD symbols, each CDD symbol being associated with a corresponding one of the plurality of antennas; and each one of the antennas transmits the corresponding set of STBC symbols and the corresponding CDD symbol.

A method of providing delay information in a multi-antenna transmission system is provided. A time delay value is selected from a set of time delay values. A mobile station is informed of information related to the selected time delay value. The same data is transmitted from a first antenna and from a second antenna. The data is transmitted from the second antenna after the data is transmitted from the first antenna according to the selected time delay value. The time delay value is selected based on a deterministic method or a random method.

In a particular embodiment, a method includes applying a first stream to antenna mapping scheme to a preamble portion of a packet. The method further includes applying a second stream to antenna mapping scheme to a data portion of the packet. The second stream to antenna mapping scheme is applied to the data portion of the packet but not to the preamble portion of the packet. The second stream to antenna mapping scheme includes a circulation scheme or a cyclic delay diversity (CDD) scheme.

Techniques for transmitting data using a combination of transmit diversity schemes are described. These transmit diversity schemes include spatial spreading, continuous beamforming, cyclic delay diversity, space-time transmit diversity (STTD), space-frequency transmit diversity (SFTD), and orthogonal transmit diversity (OTD). A transmitting entity processes one or more (ND) data symbol streams based on a transmit diversity scheme (e.g., STTD, SFTD, or OTD) to generate multiple (NC) coded symbol streams. Each data symbol stream may be sent as a single coded symbol stream or as multiple (e.g., two) coded symbol streams using STTD, SFTD, or OTD. The transmitting entity may perform spatial spreading on the NC coded symbol streams with different matrices to generate multiple (NT) transmit symbol streams for transmission from NT antennas. Additionally or alternatively, the transmitting entity may perform continuous beamforming on the NT transmit symbol streams in either the time domain or the frequency domain.

A frame timing synchronization technique for orthogonal frequency division multiplexing (OFDM) systems is presented. First, a coarse synchronization technique generates a coarse frame timing estimate. The coarse synchronization technique applies a sliding window differentiator to the output of a conventional auto-correlator to mitigate the plateau effect associated with conventional auto-correlation techniques. Second, a fine synchronization technique generates a fine frame timing estimate. The fine synchronization technique uses the coarse frame timing estimate to reduce the number of cross-correlation calculations. Additionally, the fine synchronization technique acquires a fine frame timing estimate based on a signal-to-interference ratio (SIR) metric, which is more robust to multi-paths and pseudo multi-paths caused by cyclic delay diversity (CDD) schemes than conventional cross-correlation synchronization techniques. A fine-tuning technique generates a desired frame timing estimate by searching a first signal path in a searching window around the fine frame timing estimate to further refine frame timing synchronization.

A cyclic delay diversity (CDD) technique in a multiple-antenna broadband wireless communication system is provided. An apparatus in the multiple-antenna broadband wireless communication system includes: a controller for selecting at least one sub-carrier to which CDD is applied; at least one shifter for shifting a phase of a signal mapped to the at least one selected sub-carrier; and an operator for converting the signal, which is mapped to the at least one selected sub-carrier and whose phase is shifted, and other signals mapped to the remaining sub-carriers into time-domain signals.

The invention discloses a pilot frequency inserting method for a space-frequency encoding cascade cyclic delay diversity, which is applied to a multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) system. After a data stream to be sent is encoded by an SFBC in a frequency domain, pilot frequencies are respectively inserted into each path of data stream on the basis of the number of the encoded data stream in the frequency domain. The invention further discloses a method for transmitting the diversity of the space-frequency encoding cascade cyclic delay diversity, which includes the steps that the data stream to be sent is encoded by the SFBC in the frequency domain and then pilot frequencies are respectively inserted into each path of data stream on the basis ofthe number of the encoded data stream in the frequency domain; the data stream inserted with the pilot frequencies is transformed to a time domain by Fourier transformation. After CDD is encoded, thedata is respectively sent to a transmitting antenna. The method of the invention overcomes the defect that the transmission performance of an SFBC plus CDD diversity mode is interfered due to unreasonable pilot insertion in the existing diversity transmitting method of the MIMO-OFDM system, thus improving the reliability of the whole communication system.

A feedback method for a multi-antenna system is disclosed. The feedback method for use in the multi-antenna system can reduce an amount of transmission (Tx) feedback information associated with a precoding matrix (i.e., a codebook). For example, a single codebook may include precoding matrixes associated with several ranks. A basic matrix constructing the precoding matrix is extended to a frequency axis, such that it can be used as a Cyclic Delay Diversity (CDD) structure.

Disclosed is a coordinated multi-point transmitting / receiving method using adaptive cyclic delay diversity, a system side apparatus and a receiving apparatus using the same, and a method for determining a coordinated base station set, which can cause a particular base station to have a good channel performance in a particular frequency band, which requires coordinated multi-point transmission / reception, by using adaptive cyclic delay diversity (CDD), so as to include the relevant base station in a coordinated base station set.

The present invention discloses a method, a system, a base station and a UE for confirming the cyclic delay diversity value. The present invention comprises the steps that the UE estimates the results according to the channel to obtain the optimum CDD delay value of the optimum channel which can be obtained, and feeds back the delay value to the base station; the base station chooses the optimum CDD delay value according to the received optimum CDD delay values from every user as the CDD delay value for the work of the system. With the method, system, base station and UE of the present invention, the adaptive renovation of the CDD delay value can be realized to ensure the system function to the maximum.

A base station for use in a wireless network communicating with a plurality of subscriber stations. The base station transmits in a downlink channel to a first subscriber station using a plurality of transmit antennas. The base station transmits to the first subscriber station using either a transmit diversity scheme or a beamforming scheme according to the amount of correlation between the transmit antennas observed at the first subscriber station. The base station also transmits to the first subscriber station using a cyclic delay diversity scheme having either zero delay or non-zero delay according to the amount of antenna / channel correlation observed at the first subscriber station.

The multi-antenna emission system comprises: a space-time process unit to process input data flow and output multiple frequency-domain signal data flow, a modulation unit for OFDM modulating to output relative time-domain signal flow; a data flow separation unit to select emission antenna group for every time-domain signal flow and allocate data to relative emission antenna group, and a cycle delay emission module to circular delay all time-domain signal flow on antenna groups. This invention can obtain both space and frequency diversity gains.

The invention discloses a multi-hop wireless collaboration relay scheme which can realize full-rate data transmission, and is applicable for a distributed wireless communication network. In the scheme, the data transmission from a source node S to a target node D is finished by three links; each link consists of a plurality of relay node groups in a forwarding mode; the data communication on each link is divided into a plurality of basic transmission processes; distance relay communication can be realized by cascading the basic transmission processes; each basic transmission process consists of three communication stages, a baseband signal transmitted in each communication stage is a modulation symbol obtained by linear complex field coding; each relay node group finishes the forwarding of the received signals by adopting a cycle delay diversity way; and while the high-reliability information transmission is realized, the receiving end only needs to perform joint detection on three symbols, so that the detection complexity is low, and the practical value is high. In addition, in the relay transmission process, if the relay groups in unequal numbers are distributed for the to-be-transmitted information with different priority levels and error code performance requirements, the disclosed multi-hop collaboration relay scheme can be used for the hierarchical transmission of data after being adjusted, so that the transmission quality requirements of a plurality of types of wireless service are met.

In this invention, several open-loop solutions that encompass the small delay CDD codeword cycling, codeword cycling between different re-transmissions of both small and large delay CDD are proposed. In addition, an open-loop codeword cycling method for SFBC+FSTD scheme, as well as its extension to SFBC+FSTD based HARQ, are proposed. In one method, a plurality of information bits are encoded, scrambled and modulated to generate a plurality of modulation symbols. The plurality of modulation symbols are mapped onto the subcarriers in at least one transmission layer of a transmission resource. The modulation symbols are then precoded by using a matrix for cyclic delay diversity and a set of codewords from a certain codebook to generate a plurality of precoded symbols. The codewords are cycled for every a certain number of subcarriers. Finally, the precoded symbols are transmitted via a plurality of transmission antennas.

A gap filler apparatus providing cyclic delay diversity in a digital multimedia broadcasting (DMB) system. In the gap filler apparatus, a receiver receives an orthogonal frequency division multiplexing (OFDM) signal transmitted as a broadcasting signal. A symbol synchronization unit acquires symbol synchronization of the OFDM signal, detects a guard interval of an OFDM symbol using the symbol synchronization, determines a sample length, by which the OFDM symbol is cyclic-delayed within the guard interval, and cyclic-delays the OFDM signal by the determined sample length. An amplifier amplifies the cyclic-delayed OFDM signal. A transmitter transmits the amplified OFDM signal to a wireless network.

A cyclic delay diversity (CDD) technique in a multiple-antenna broadband wireless communication system is provided. An apparatus in the multiple-antenna broadband wireless communication system includes: a controller for selecting at least one sub-carrier to which CDD is applied; at least one shifter for shifting a phase of a signal mapped to the at least one selected sub-carrier; and an operator for converting the signal, which is mapped to the at least one selected sub-carrier and whose phase is shifted, and other signals mapped to the remaining sub-carriers into time-domain signals.

Disclosed is a method for compensating for frequency attenuation using adaptive cyclic delay diversity, and a transmitting apparatus and method and a receiving apparatus and method using the same. In the method, a receiving side feeds back information on an antenna to be delayed and an adaptive CDD delay value for the antenna to a transmitting side, and the transmitting side performs a cyclic delay transmission based on the provided cyclic delay value, so as to improve the reception frequency response characteristics.

An apparatus and a method for simultaneously supporting Multiple-Input Multiple-Output (MIMO) and beamforming in a wireless communication system are provided. In the method, two data streams are mapped to each of all of 2N transmission antennas; the two data streams are multiplied by different Cyclic Delay Diversity (CDD) phase sequences; the two data streams multiplied by the different CDD phase sequences for each transmission antenna are added; and the added data stream is multiplied by a beamforming coefficient and transmitted for each transmission antenna.

Disclosed are systems, apparatus, devices, methods, media, products, and other implementations, including a method that includes controllably modifying, at a first wireless device, an original unmodified value of at least one PHY-layer signal parameter, such as amplitude, frequency, timestamp, gain, signal equalization, and / or any combination thereof, of a signal according to at least one pre-determined varying signal modification process. The method further includes transmitting to a second wireless device the signal with the controllably modified value of the at least one PHY-layer signal parameter, with the transmitted signal configured to facilitate position determination of the second wireless device when the original unmodified value of the at least one PHY-layer signal parameter is determined at the second wireless device from the controllably modified value of the at least one PHY-layer signal parameter.

The invention discloses a transmitting device and receiving device of a spectral domain channel multiplexing transmission system and method thereof. The emitting device is characterized in that a cyclic delay modulation module is overlaid on a CDD-OFDM (Cyclic Delay Diversity-Orthogonal Frequency Division Multiplexing) transmitting module; the cyclic delay modulation module is used for independently mapping an information bit stream into a cyclic delay modulation vector; and the cyclic delay diversity-orthogonal frequency division multiplexing transmitting module is used for carrying out corresponding cyclic shift operation on an orthogonal frequency division multiplexing symbol according to a modulated cyclic delay vector and modulating the cyclic self-correlation function of a CDD-OFDM signal, therefore a spectral domain channel is established. The invention realizes the multiplexing of an OFDM modulation channel and a cyclic delay modulation channel by embedding the cyclic delay modulation module into the traditional CDD-OFDM standard system, thereby solving the problem that the spectral domain channel is multiplexed on a multi-carrier frequency domain channel; and in addition,the invention obtains the cyclic delay diversity without consuming extra transmitting power and bandwidths and also enhances the transmission rate of the system.