49 results about "Walsh sequences" patented technology

It is possible to improve the CQI reception performance even when a delay is caused in a propagation path, a transmission timing error is caused, or a residual interference is generated between cyclic shift amounts of different ZC sequences. For the second symbol and the sixth symbol of the ACK/NACK signal which are multiplexed by RS of CQI, (+, +) or (−, −) is applied to a partial sequence of the Walsh sequence. For RS of CQI transmitted from a mobile station, + is added as an RS phase of the second symbol and − is added as an RS phase of the sixth symbol. A base station (100) receives multiplexed signals of ACK/NACK signals and CQI signals transmitted from a plurality of mobile stations. An RS synthesis unit (119) performs synthesis by aligning the RS phase of CQI.

A method for deep paging in a communication system employing orthogonal channelizing codes, such as Walsh sequences, of predetermined length m, that does not require a high powered paging channel. The method includes the steps of generating a paging channel message which is combined with a Walsh sequence having a length greater than or equal to 2m, and transmitting the paging channel message at a data rate of less than 4800 bits per second (bps). By transmitting the paging channel message at a low data rate and integrating collected energy over a period longer by a factor on the order of 1000, the message is able to penetrate buildings and other structures or high attenuation environments, thereby allowing one to successfully page a user terminal that is inside such a structure or area. Preferably, the paging channel message is formed using an auxiliary Walsh sequence on the order of 65536 chips in length, and the data rate is less than 10 bps.

The invention relates to an MC-CDMA-based underwater acoustic communication system and a PAPR suppression method, and the method comprises the steps: enabling a transmitting end to code input data after mapping, carrying out the serial-parallel conversion of the input data into q sub-data streams bi, and copying the bit of each sub-data stream bi into Np parts; generating a chaotic sequence according to the number U of subcarriers, and circularly multiplying the chaotic sequence by the basic spread spectrum sequence to generate a chaotic composite spread spectrum sequence C; multiplying each sub-data stream bi by the chaotic composite spread spectrum sequence C, and converting the multiplied sub-data streams bi into time domain signals through IFFT; and calculating the peak-to-average power ratio PAPR of the system according to the frequency band signal after up-conversion sampling. According to the PAPR suppression method disclosed by the invention, by changing the generation mode ofthe spreading code, the chaotic sequence is cyclically multiplied by basic spreading sequences such as an M sequence, a Walsh sequence or a completely complementary CCS sequence to generate a chaoticcomposite spreading sequence, so that the peak-to-average power ratio suppression characteristic of the system is improved. Compared with an amplitude limiting method, the method does not cause in-band distortion and out-of-band leakage. Compared with a probability method, the method is simple in operation mode and low in operation complexity.

The present invention is a novel and improved method and apparatus for transmitting data in a multiple carrier CDMA communication system. In the first implementation of the present invention, the data is encoded and the resulting encoded symbols are divided up and transmitted on different frequencies. The encoded symbols are provided to a symbol repetition means which keeps the symbol rate of data to be transmitted fixed. In a second embodiment, no symbol repetition is provided and variable length Walsh sequences are used to handle data rate variations.

The invention provides a method and system for constructing a no-hit-zone bipolar frequency hopping code. The method for constructing the no-hit-zone bipolar frequency hopping code includes the steps that first, a no-hit-zone frequency hopping sequence NHZ is constructed; second, a Walsh sequence is constructed; third, the no-hit-zone frequency hopping sequence NHZ and the Walsh sequence are combined to form the no-hit-zone bipolar frequency hopping code. The method and system for constructing the no-hit-zone bipolar frequency hopping code have the advantages that according to the constructed no-hit-zone bipolar frequency hopping code, all codons are totally orthogonal as long as the delay between users is within a zero correlation zone, so that multi-site interference and beat noise of a two-dimensional coherent OCDMA system will be completely eliminated, and the near-far effect of the two-dimensional coherent OCDMA system can also be eliminated. Therefore, by means of the no-hit-zone bipolar frequency hopping code constructed through the method and system, a high-capacity two-dimensional coherent OCDMA system can be achieved, and the no-hit-zone bipolar frequency hopping code can be applied to an optical access network, an optical local area network, an optical code label switching network, an optical fiber sensor network and the like.

The invention provides a constructing method and system for the two-dimensional bipolar code of a zero-correlation region in time/frequency domain. The constructing method comprises the steps that A a time domain zero-correlation region spread-spectrum sequence LA with the zero-correlation region is constructed; B a single coincidence sequence in frequency domain is constructed; C a Walsh sequence is constructed; D the time domain zero-correlation region spread-spectrum sequence of the zero-correlation region is combined with the single coincidence sequence in frequency domain are combined to form a time/frequency domain zero-correlation region two-dimensional optical orthogonal code; and E the time/frequency domain zero-correlation region two-dimensional optical orthogonal code is combined with the Walsh sequence to form the two-dimensional bipolar code of the zero-correlation region in time/frequency domain. The method and the system have the advantages that multi-site interference and beat noise of a two-dimensional coherent OCDMA system are completely eliminated; the near-far effect of the two-dimensional coherent OCDMA system can be eliminated; the large-capacity two-dimensional coherent OCDMA system can be realized; and the method and the system can be applied to an optical access network, an optical local area network, an optical code tag switching network, a fiber optic sensor network and the like.

A wireless communication apparatus capable of minimizing the degradation in separation characteristic of a code multiplexed response signal. In this apparatus, a control part (209) controls both a ZC sequence to be used in a primary spreading in a spreading part (214) and a Walsh sequence to be used in a secondary spreading in a spreading part (217) so as to allow a very small circular shift interval of the ZC sequence to absorb the interference components remaining in the response signal; the spreading part (214) uses the ZC sequence set by the control part (209) to primary spread the response signal; and the spreading part (217) uses the Walsh sequence set by the control part (209) to secondary spread the response signal to which CP has been added.

A receiver receives elements of a signal sequence. A state generator generates a sequence of addresses to translate between a pseudonoise sequence and a Walsh sequence. A storage medium, coupled to the receiver and the state generator, stores each element of the signal sequence at a given address according to the sequence of addresses.

The invention relates to a method for creating frequency domain zero correlation area code and the device and multi-carrier CDMA system. In the embodiment, Kronecker product operation is performed by initiation sequence and Walsh sequence generated according to the system parameter to acquire frequency domain zero correlation area code; the system adopts the frequency domain zero correlation area code for data transmission and user identification, which can effectively avoid interference between users due to selective fading of channel frequency, and support more users compared to system of existing frequency domain zero correlation area code and its selection scheme and support multi-speed service , and does not need code reallocation when active user number changes.

A method of interrogation/response in an IFF type Mode 5 communications system comprises at least the following steps: modulating the header of an interrogation message by using an orthogonal or substantially orthogonal function; detecting the modulation function used for the header and determining the algorithm for the decoding of the information contained in the message. The modulation function is a 16-bit Walsh sequence.

A method and apparatus for providing orthogonal spot beams (14a, 14b), sectors (16a, 16b), and picocells (18), by using orthogonal auxiliary pilots and different Walsh traffic channels in adjacent areas. According to the IS-95 standard, the pilot signal is covered with the 64-chip Walsh sequence zero. Designating the 64-chip all zeros Walsh sequence as P and the 64-chip all one sequence as M, additional pilot signals are provided in the present invention by concatenating the P and the M sequences. Thus, for two pilot signals, pilot Walsh sequences of PP and PM can be used. For four pilot signals, pilot Walsh sequences of PPPP, PMPM, PPMM, and PMMP can be used. In general, the required number of pilot Walsh sequences can be generated by substituting each bit in an K-bit Walsh sequence with the 64-chip all zeros P or all ones M sequence, depending on the value of that bit.

Systems and methodologies are described that facilitate increasing system capacity in a code-limited WCDMA (e.g., TDD, FDD, ) wireless communication environment. According to one aspect, a larger code space can be defined by introducing multiple code clusters within a sector, wherein each cluster has a unique scrambling code. Codes within a cluster can have orthogonal Walsh sequences that can be assigned to user devices to facilitate communicating over a wireless network and can overlap with codes in another cluster. The unique scrambling code assigned to each cluster can ensure that duplicate Walsh sequences in another cluster in the same sector appear as a pseudo-noise codes.

The invention discloses a fractional order multi-carrier multi-code-shift multi-system differential chaos shift keying modulation and demodulation method and a modem, and relates to the technical field of communication signal processing. The modulation and demodulation method comprises the steps: carrying out the serial-parallel conversion of a to-be-transmitted multi-system information packet into P-path parallel multi-system information, carrying out the bit/symbol conversion to obtain P-path multi-system parallel constellation symbols, and meanwhile, generating a fractional order chaotic signal by a fractional order chaotic generator; generating a Walsh code by a Hadamard matrix, selecting a signal obtained by multiplying a first Walsh sequence by a fractional order chaos signal as a reference signal, multiplying other 2P different Walsh sequences by the fractional order chaos signal, inputting the multiplied signals into a multi-system DCSK modulator, respectively acquiring P paths of multi-system DCSK modulation signals through modulation, adding the reference signal and the P paths of multi-system DCSK modulation signals, after completing multi-carrier modulation, sending the information to a channel for transmission, and carrying out related demodulation at a receiving end to recover original information. According to the method, the bit error rate is lower, the higher data rate is realized, and the confidentiality is higher.

The invention provides an all-zero block detection method suitable for HEVC and relates to the technical field of video processing; a walsh transform WT coefficient matrix of a prediction residual sub-block, which is arranged according to a walsh sequence, is calculated; a walsh sequence WT coefficient matrix of the same order as the TB is calculated according to the walsh sequence WT coefficientmatrix of the prediction residual sub-block; and an all-zero block is detected according to the walsh sequence WT transform coefficient or a prediction residual error. Compared with an algorithm basedon SAD and SATD, a maximum transform coefficient is directly used for detecting the all-zero block; error detection caused by the residual energy distribution difference is avoided; therefore, the detection efficiency is greatly improved. According to the method, the full-zero block in the UQ can be detected, and the all-zero block in the RDOQ can also be detected; high detection efficiency is achieved for all the four-size all-zero blocks; the loss of the rate-distortion performance of an encoder is small, which can be basically ignored; overall time consumption of conversion/quantization operation is obviously reduced, and the encoding speed is increased.