68 results about "Space frequency coding" patented technology

The invention discloses a broadband wireless sensor network transmission scheme based on amplify-and-forward single-node cooperation communication. The scheme is as follows: a source node is firstly used to make an orthogonal space-frequency coding to an original signal, two time slots are respectively used to transmit orthogonal signal frames, then a pilot frequency is inserted and coded signals are subject to IFFT operation to fight against the multi-path attenuation, the coded signals are converted onto a time domain, and the serial data flow is broadcast and sent after the insertion of a cyclic prefix and a training sequence. A first time slot relay node receives signals of the source node, makes frequency deviation and phase compensation, then adopts an amplify-and-forward protocol to synchronously send the processed signals to an information sink node at a second time slot and the source node; an information sink receiver receives a mixed signal from two independent channels, firstly detects a frame head of the signal of the second time slot, then synchronizes with the frame head, then carries out FFT operation to the signal part, converts the signal back to the frequency domain, and performs space-frequency decoding to obtain an original sending symbol. The scheme is simple and easy to operate, can effectively improve the error code rate performance of the system, has strong practicability, and is convenient for the realization of the hardware.

The invention relates to the mobile communication field, disclosing a space frequency coding based multi-antenna transmission diversity method and the system thereof. When the number of transmission antenna is over 2, a coding can be accomplished within an OFDM symbol period and meanwhile a diversity gain similar to STTD+CSD can be obtained. The invention uses space frequency coding to obtain the diversity gain and at the same time introduces phase offset in the frequency-domain to obtain extra frequency diversity similar to CSD through the channel of the frequency-domain data. The phase offset satisfies: the frequency-domain data loaded in the sub-carrier wave set used in SFTD on the same antenna possesses the same phase offset and the frequency-domain data loaded between the sub-carrier wave sets possesses different phase offsets. Moreover, the frequency-domain data loaded on the same sub-carrier wave on different antenna in the same antenna stack possesses different phase offsets.

The invention relates to a compressed sensing PIE system based on space-frequency coding. In a transmitter, a channel encoder, a modulator, an orthogonal converter, a symbol interleaver, a serial-to-parallel converter and a space-frequency encoder are successively connected in series, the space-frequency encoder is connected with two subcarrier mapping devices of the same structure, and each subcarrier mapping device is successively connected with an up sampler, a reverse discrete Fourier transformer, a cyclic prefix adder, a parallel-to-serial converter, a D/A conversion and RF emitter and an emission antenna. A receiver comprises a reception antenna, an RF front-end converter, an A/D converter, a Doppler frequency offset estimator, a Doppler frequency offset compensator, a cyclic prefix remover, a discrete Fourier transformer, a compressed sensing interference eliminator, a frequency-domain down sampler, a channel estimator, a space-frequency decoder, a symbolic solution interleaver, a reverse orthogonal converter and a channel decoder successively in serial connection. The compressed sensing algorithm can be directly utilized to reconstruct pulse signals of a range finder and converts the pulse signals to the frequency domain for elimination, and thus, the pulse signals of the range finder are effectively inhibited.

A new diversity scheme for orthogonal frequency division multiplexing/multi-input multi-output (OFDM/MIMO) systems. The new diversity scheme, i.e., turbo layered space-frequency coded OFDM (TLSFC-OFDM), uses the turbo principle with space hopping (SH). The TLSFC-OFDM system uses a successive interference cancellation (SIC) algorithm to reduce the number of iterations. As a result, this scheme reduces computational complexity. Simulation results show that the SIC-based TLSFC-OFDM system outperforms a conventional OFDM/Horizontal Bell Labs Layered Space-Time (H-BLAST) system using a horizontal coding scheme.

The invention discloses a method for reducing a peak-to-average power ratio of multiple input multiple output (MIMO) - orthogonal frequency division multiplexing (OFDM) signal for space-frequency coding. On a transmitter end, data is coded, interlaced, modulated and alamounti space-frequency coded to obtain a group of frequency-domain sequence, the group of frequency-domain sequence is grouped, so multiple groups of candidate time-domain signals are obtained by selecting appropriate parameters, and a group of time-domain signals with the minimum peak-to-average power ratio (PAPR) is selected to be transmitted. On the end of a receiver, after the operation of a received signal such as fast fourier transformation (FFT), estimation of a channel, space-frequency coding and the like, a frequency-domain signal which is superimposed by the channel noise is obtained, and the hard decision is performed on the frequency-domain signal to obtain a nose-free frequency-domain signal. The signal is restored according to all possible combination ways to obtain candidate data, and only the data which is restored by adopting a correct restoring way conforms to the original modulation constellation.The method can effectively reduce the peak-to-average power ratio of the MIMO-OFDM signal, is free from transmitting the side information, improves the frequency band utilization rate of the system, and can be applied to different communication systems based on the space-frequency coding-based MIMO-OFDM technology.

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.

The invention discloses a method for transmitting an anti-noise wireless multi-media broadcast signal in a single frequency network. In the method, the wireless multi-media broadcast signal is transmitted to an air wireless channel by a wireless multi-media broadcast transmitter in the single frequency network through the following steps: the multimedia data streams are processed by a central data manager; a network data manager carries out LDPC (Low Density Parity Check) coding, code element modulating and constellation rotation on bit streams; space-frequency coding modulation is carried out; discrete data sample value blocks in the time domain and embedded discrete sample value blocks of training sequences in the time domain are superposed to form frames; pulse shaping is carried out; up-conversion is carried out on a baseband signal to a carrier wave to form a radio-frequency signal to be transmitted to the air wireless channel; and a receiver terminal receives and processes the signal transmitted by the wireless multi-media broadcast transmitter in the single frequency network. The method has the advantages of short synchronous receipt time, environmental background noise resistance, large-range controllable multiple services in the single frequency network, etc.

The invention discloses a method for processing multiuser multiple-input multiple-output (MU-MIMO) based on orthogonal diversity, which comprises the steps of: precoding data flows of different users by independent delamination and specific orthogonal diversity, and mapping the data in a space-frequency coded matrix; carrying out multiuser precoding or beam forming (BF) processing on data of different users in the space-frequency coded matrix; and transmitting the processed data subjected to resource mapping outside through a transmitting antenna. The invention also discloses a device for processing MU-MIMO based on orthogonal diversity. By using the method and the device, the processing of multiuser transmitting diversity is realized, the resources of the antenna and carrier waves are fully used, and more users can be multiplexed under the same resource consumption.

A communication system for transmitting encoded signals over a communication channel is disclosed. The system includes a transmitter, which has a source that is configured to output a plurality of input signals. The transmitter also includes an encoder that is configured to generate a plurality of output signals in response to the plurality of the input signals to output a code word according to the plurality of output signals, wherein the code word has a predetermined algebraic construction for space-frequency coding based upon the communication channel being characterized as a frequency selective block fading channel. Further, the transmitter includes a modulator that is configured to modulate the code word for transmission over the communication channel, and a plurality of transmit antennas that configured to transmit the modulated code word over the communication channel. The system encompasses a receiver that includes a plurality of receive antennas, in which the receiver is configured to receive the transmitted code word via the plurality of receive antennas. The receiver employs an OFDM-front end to transform the Intersymbol Interference (ISI) channel characteristics of the communication channel to selective block fading characteristics.

The present invention relates to space-time or space-frequency coding in cellular systems. The same data is transmitted from different antennas with different coverage areas, corresponding to different cells. The different data streams have different parts of the space-time block codes applied. A mobile terminal can combine the different parts of the space-time block codes in different received signals. This provides better performance than the known techniques for single frequency networks. The invention can also be applied to antennas with different coverage areas from the same site, and different beams formed with antenna arrays.

The invention relates to a method for sending signal grouped, which comprises: A, processing serial and parallel conversions and FFT conversion on the input signal; B, dividing the input signal into two same paths of signals, to be coded; the odd and even positions of first path are formed by the data sequence of two signals; the odd and even positions of second path are formed by the data conjugate sequences of two signals, while its odd or even positions are negated on the conjugated data at the odd or even position of first path; C, modulating two paths, to be sent by antenna. The invention also discloses a relative device. The invention can confirm the low-peak uniform bit of output signal.

The embodiment of the invention provides diversity transmission method and device of an OFDM (Orthogonal Frequency Division Multiplexing) system. The method comprises the steps of: grouping OFDM subcarriers, wherein the number N of subcarriers in each group is an integral multiple of the number M of antenna port, and M is an integral multiple of 4; carrying out space frequency coding with SFBC (Space Frequency Block Code)+FSTD (Frequency Switch Transmit Diversity) on N subcarriers in each group at M antenna ports, wherein different subcarrier mapping modes are adopted on the subcarriers in odd number groups and the subcarriers in even number groups; and carrying out diversity transmission on data symbols of M antenna ports according to a space frequency coding result. The embodiment of the invention improves the space diversity effect through a mode of alternatively using different subcarrier mapping modes, thereby avoiding the situation that because of the adoption of a fixed mapping mode, the link performance is influenced when deep fading occurs in a wider frequency band range.

The invention discloses a diversifying method of an MIMO-OFDM system based on space-frequency coding, when the transmitting antenna is more than 2, better frequency gain effect can still be obtained. The diversifying method comprises that: after rearranging data in a data packet needed to be transmitted, a transmitting party carries out space-frequency coding to the data and then transmits the data; the rearrangement is used for causing the data transmitted by each antenna on sub-carriers with the same frequency points to be different; when receiving the data, a receiving party carries out de-rearrangement according to the rearrangement manner of the transmitting party after the receiving of all the data packets is finished, and carries out space-frequency decoding after the same user data is obtained on the corresponding sub-carriers so as to obtain the original user data.

The invention discloses a channel estimation method applicable to cyclic delay diversity mode of a space-frequency encoding cascade; wherein, adjacent two pilot frequencies on a same data stream are respectively positioned at an odd location and an even location of subcarrier. The pilot frequency at the odd location on the data stream is used for estimating an equivalent channel response at the odd location of an antenna while the pilot frequency at the even location on the data stream is used for estimating the equivalent channel response at the even location of the antenna. By adopting the channel estimation method of the invention, not only the bit error rate performance is improved, but also the complexity of the channel estimation is reduced, thus ensuring the accuracy of the channelestimation and improving the reliability of the whole communication system.

This invention discloses a transmission method of orthogonal frequency division multiplexing with multiple inputs and outputs, including: (1) an emitting end processes space-frequency coding to emitted data and processes space-time coding to the data, then processes serial/parallel transformation, inverse fast Fourier transform algorithmic transformation, adding cyclic prefix, parallel/serial transformation, then emits the data; (2) after receiving the data received from the emitting end, a receiving end respectively processes removing cyclic prefix, serial/parallel transformation, inverse fast Fourier transform algorithmic transformation and parallel/serial transformation to the received data in two symbol periods, then processes space-time decoding to the data, at last processes data combination. This invention further discloses a MIMO OFDM system coding emitter and a receiver, and an emitting method and a receiving method. This invention obtains an effective transreceiver suitable for adopting the MIMO OFDM system of space-time frequency coding and corresponding transmission method through adjusting a transreceiver mechanism under the condition of not increasing the transreceiver complexity.

A communication system for transmitting encoded signals over a communication channel is disclosed. The system includes a transmitter, which has a source that outputs a message signal. The transmitter also includes an encoder that generates a code word in response to the message signal. The code word has a construction that defines a plurality of paths associated with an intersymbol interference (ISI) environment of the communication channel, wherein the code word achieves a diversity based upon the number of transmit antennas and the number of ISI paths. Further, the transmitter includes a modulator that modulates the code word for transmission over the communication channel, and multiple antennas that transmit the modulated code word over the communication channel. The system encompasses a receiver that receives the transmitted code word via a number of receive antennas.

The embodiment of the invention discloses a construction method of a space-frequency code, comprising: generating a space-time block encoding matrix; repeating the space-time block encoding matrix for gamma times to obtain a repetition matrix, wherein gamma is the frequency diversity module; cascading the repetition matrix to obtain the space-frequency code word. The embodiment of the invention also discloses a construction method of the space-frequency code, comprising: grouping the data symbol assembly, repeating each group of symbols for gamma times, to obtain a new data symbol assembly, wherein gamma is the frequency diversity module; performing the orthotropic space-time block encoding on the new data symbol assembly, to obtain the space-frequency code word. According to the space-frequency code constructed by the two methods, the orthogonality of the generated entire diversity space-frequency code under the normal frequency response is ensured, thereby lowering the complexity of the coding, furthermore advancing the performance of the space-frequency code under different channels.

The invention relates to a method for grouped sending signal, which comprises: A, serially and parallel converting the input signal; B, dividing the converted signal into two paths with same length, then treating them with FFT; C, processing idle-frequency coding on the transformed signals; D, modulating the signals to be sent out via two antennas. The invention also provides a device for grouped sending signal. The invention, via FFT transforming and coding two paths of signals, can confirm the low-peak property of output signal.