317 results about "Spread factor" patented technology

A method of adaptive Walsh code allocation in a wireless communication system. The method includes the step of each voice user transmitting quality condition signal, such as a pilot signal strength measurement to a corresponding base station. Upon receiving each quality condition signal, the method includes determining a spreading factor for each voice user in response to its quality condition signal. A Walsh code is thereafter allocated to each voice user in response to the determined corresponding spreading factor. Thus, for example, if the quality condition signal of a first voice user is relatively higher than the quality condition signal of a second voice user, the spreading factor allocated to the first voice user should be longer than the spreading factor of the second voice user.

The CDMA communication device of the present invention includes a spreading unit, radio transmitters, and a control device that includes a setting unit and a determination unit. The spreading unit spreads and multiplexes user data of users. The radio transmitters are provided correspondingly to each of a plurality of frequencies, and modulate with the corresponding frequencies the user data that are supplied from the spreading unit. The determination unit determines the working frequency of users based on the spread factor value of the user data. The setting unit sets the spread factor of the user data in the spreading unit. The setting unit further performs setting of the spreading unit such that user data that have undergone spreading are supplied to the radio transmitter that has been provided correspondingly to the frequency determined by the determination unit.

An orthogonal variable spreading factor (OVSF) of one dimension represented by coding tree is extended into two dimensions and applied simultaneously in both directions, frequency axis direction and time axis direction when carrying out spreading of two dimensions of frequency axis direction and time axis direction. For example, the transmission data is first spread by OVSF code of one dimension in the frequency axis direction (obtained from frequency axis direction OVSF code assignment section 11), and the result is spread by OVSF code of one dimension in time axis direction (obtained from time axis direction OVSF code assignment section 13, which is selected independent of frequency axis direction) in each of two-dimensional spreading sections 1-1 to 1-8.

A base station, a mobile station, a radio communications system, and a radio transmission method are disclosed. The base station includes a control information determining unit configured to determine control information that includes a spreading factor, the number of chip repetitions, and a phase unique to the mobile station, based on at least one of information about the type of cell environments in which the mobile station is present, information about the number of mobile stations that are present in the cell, information about information rate required by the mobile station, information about a type of traffic, information about a radio parameter of the mobile station, information about a propagation path condition, and information about interference from an adjacent cell, and configured to transmit the spreading factor, the number of chip repetitions, and the unique phase of the mobile station that is determined to the mobile station.

Disclosed is a method and apparatus for providing uplink packet data services through an E-DCH in an asynchronous WCDMA system. A transport block size (TBS) for transmitting uplink transport channel data is determined. A combination of a spreading factor and a modulation scheme for uplink channel data transmission, corresponding to the determined TBS, is selected according to transmittable physical channel data bit sizes and puncturing limit values. The TBS is transmitted by incorporating it into control information of the uplink transport channel data. The modulation scheme and spreading factor combination is determined based on a physical channel data bit size that maximizes transmission efficiency and minimizes the number of punctured bits, without requiring an additional physical channel in transmitting the uplink data having the TBS. This method maximizes uplink transmission efficiency to save transmission resources and reduces signaling overhead required to transmit E-DCH control information.

In power control in an OFDM-CDMA system for creating a number of subcarrier components by multiplying a plurality of symbols by channelization codes of a length that conforms to a spreading factor, and transmitting each of the subcarrier components by a corresponding subcarrier, a subcarrier band is divided into a plural subcarrier blocks, the number of the subcarriers in each block is a whole-number multiple of the spreading factor, an identical transmission power is assigned to each subcarrier in each subcarrier block obtained by such division, and transmission power is controlled from one subcarrier block to another.

For a bandwidth extension of an audio signal, in a signal spreader the audio signal is temporally spread by a spread factor greater than 1. The temporally spread audio signal is then supplied to a demicator to decimate the temporally spread version by a decimation factor matched to the spread factor. The band generated by this decimation operation is extracted and distorted, and finally combined with the audio signal to obtain a bandwidth extended audio signal. A phase vocoder in the filterbank implementation or transformation implementation may be used for signal spreading.

A method for allocating a physical hybrid ARQ indicator channel (PHICH) is disclosed. The method includes allocating a CDM group according to a cyclic prefix type in consideration of a ratio of the numbers of necessary CDM groups according to spreading factors, and allocating a PHICH to the allocated CDM group. The PHICH includes an ACK / NACK signal multiplexed by code division multiplexing (CDM). Therefore, resources for PHICH transmission are efficiently allocated and a transmission structure can be maintained irrespective of a spreading factor.

A reception method and receiver structure that are relatively simple, that have close to optimum performance, and that use high order modulation combined with a low spreading factor are disclosed. The method receives a signal transmittal in the form of sequences of coded binary symbols comprising both predefined pilot symbols and date symbols multiplied by a spreading sequence. The method also includes a step of determining a channel estimate using received predefined pilot symbols. A system for receiving a signal transmitted on a multipath transmission channel using a spread spectrum technique and low spreading factor is also disclosed.

A MC-CDMA handset has a receiver (30) that estimates SIR based on a spread factor of a pilot channel. More particularly, a spread spectrum signal including a pilot channel and multiple data channels is received. The pilot channel is despread using a spread factor (SF). The SIR for the despread pilot channel is calculated and stored in a memory (34). The SF is then incremented and used to despread the pilot channel again, and this process is repeated for all of SF. The stored SIRs are compared to a threshold value in ascending order of the SFs. The first SIR value to fall below the threshold value is used as the estimated SIR result.

Embodiments of the present invention include a method for performing joint time synchronization and carrier frequency offset estimation in a wireless communication system, comprising steps of: on a transmitter: performing frequency domain spreading and interleaving on input data by using a predetermined spreading factor (SF) to generate a frequency domain training symbol; performing Inverse Discrete Fourier Transformation (IDFT) on the generated frequency domain training symbol to generate a first time domain training symbol; reversely copying the generated first time domain training symbol to a second time domain training symbol such that a complete training sequence is formed; and on a receiver: detecting an average power of received signals to judge the coming of a training sequence, and performing coarse frame synchronization; performing joint fine frame synchronization and carrier frequency offset estimation based on a received training sequence; and compensating for the carrier frequency offset based on the carrier frequency offset estimation result so as to eliminate the carrier frequency offset. In addition, embodiments of the present invention also include an apparatus for performing joint time synchronization and carrier frequency offset estimation and a method for generating a training sequence.

Aspects of a method and system for a variable spreading factor Walsh Hadamard Transform engine are presented. Aspects of the system may include a variable spreading factor Fast Walsh Hadamard Transform engine that enables spread spectrum encoding of data from each of a plurality of data sources. A plurality of spreading factors may be utilized wherein at least 2 of the plurality of spreading factors differ. The variable spreading factor Fast Walsh Hadamard Transform engine may enable combination of a plurality of spread spectrum encoded data to form a data vector.

A transmitter (200) used in a wireless communication system based on an orthogonal frequency division multiplexing (OFDM) scheme includes a determination unit (216) configured to determine a spreading factor and an amplitude for a control channel based on at least one of signal quality information and interference information in data transmission, a multiplexing unit (212) configured to multiplex a data channel with the control channel having been code-spread based on the spreading factor and the amplitude, and means (214) configured to modulate the multiplexed signal in the OFDM scheme and transmit the modulated signal as OFDM symbols.

The present invention provides a detection method in which a CDMA-coded data signal is transmitted in the form of a data stream of spread data bursts between a transmitter and a receiver, hierarchical CDMA codes being used for the transmission. In a first step, codes having a smaller spreading factor than a maximally to be detected spreading factor (SF) are detected. In a second step, codes having a larger spreading factor than in the previous step are detected, the detection results of the first step being taken into account. In a third step, the detection process is broken off if all codes are detected, or otherwise the second step is repeated with the detection results last obtained in each instance, until all codes are detected.

Disclosed is an adaptive channel estimator for improving a performance of a general channel estimator in a mobile communication system, and a method for controlling the same. The adaptive channel estimator further detects a noise level of a channel and a channel speed, and implements an optimum noise elimination filter on the basis of the detected noise level and channel speed. A comparison between mapping degrees predetermined by the detected noise level and channel speed allows an optimum noise elimination filter to be implemented, If such a channel estimator is implemented, then optimum packet data transmission is available for not only a low-speed channel but also a high-speed channel. A channel compensation caused by a difference between a spreading factor (SF) of a pilot channel and a spreading factor (SF) of a data channel can be compensated on the condition that a slope compensator executed by a SF ratio is controlled by a filter coefficient controller.

A transmitter comprises a first spreading unit configured to multiply each of multiple data symbols with a first spreading code sequence of a first spreading factor; a compression and repetition unit configured to compress output signals of the first spreading unit in time domain and repeat the compressed signal L times (where L is a natural number greater than or equal to 2); a phase modulation unit configured to multiply the compressed and repeated signal with a user dependent phase and output a data block consisting of L sub-blocks; a second spreading unit configured to replicate the data block according to a second spreading factor and multiply each set of the replicated sub-blocks with a second spreading code sequence of the second spreading factor to produce a two-dimensionally spread signal; and a wireless transmission unit configured to transmit the two-dimensionally spread signal using a single-carrier transmission scheme.

A method of noise factor computation for a chip equalizer in a spread spectrum receiver, the method including the steps of: computing channel and noise variance estimates for multiple resolvable fading paths of chip signals received at the spread spectrum receiver; computing the sum of power of the channel estimates; estimating the chip energy of the chip signals; and computing the noise factor from the chip energy estimate, channel and noise variance estimates, sum of power of the channel estimates, and spreading factor of the pilot signal.

Disclosed is a method and system thereof for transmitting a Voice over Internet Protocol (VoIP) packet over a primary channel and a supplemental channel belonging to a shared pool of supplemental channels in a wireless communications network such that Orthogonal Variable Spreading Factor (OVSF) codes associated with higher spreading factors (SF) may be used, thereby minimizing the adverse effects on system resources associated with implementing VoIP over downlink Dedicated CHannels (DCH). In the method and system, if an entire VoIP packet cannot be transmitted over a single transmission time interval on a primary channel, a specific supplemental channel (or code associated therewith) is assigned to a User Equipment (UE) to which the VoIP packet is intended. A portion of the VoIP packet is transmitted to the UE over a Dedicated Physical Data CHannel (DPDCH) on the primary channel, and another portion of the VoIP packet is transmitted to the UE over a DPDCH on the supplemental channel. The assigned specific OVSF code (or supplemental channel associated therewith) belongs to a set of supplemental OVSF codes assigned to the UE, and the set of assigned supplemental OVSF codes belongs to a shared pool of supplemental OVSF codes reserved at Node B. The identity of the assigned specific supplemental OVSF code used for the supplemental channel is indicated to the UE over a Dedicated Physical Control CHannel (DPCCH) on the primary channel. The UE examines the DPCCH on the primary channel to determine whether a specific supplemental channel (or code associated therewith) has been assigned to it. If a specific supplemental channel was assigned, then the UE will decode the data on the assigned specific supplemental channel along with the data on its primary channel. Otherwise, the UE will only decode the data on its primary channel.

In one disclosed embodiment, data information is stored in a buffer in a transmitter. The data information is transmitted on a shared channel and control information for recovering the associated data information is transmitted on a dedicated channel. The shared and dedicated channels can be, for example, different portions of the frequency band. The control information can include a spreading factor used to spread the data at the transmitter. For example, the spreading factor can be the length of the Walsh function orthogonal coding used to spread the data. The control information is received over the dedicated channel before the associated data information is received over the shared channel. The control information is then used to recover the associated data information. For example, knowing the spreading factor from the control information, the correct Walsh function can be selected to de-spread, i.e. to Walsh de-cover, the data information.

A wireless data communication system includes a high speed dedicated physical control channel (EU-DPCCH) used with transmissions from a mobile device to support an uplink high speed data channel. In one example the EU-DPCCH has a sub frame structure that is the same as an associated dedicated data channel and a fixed spreading factor. The EU-DPCCH allows communicating control information from the mobile device such as a pilot reference, hybrid automatic repeat request information, and backlog information regarding a buffer of the mobile device.

A method for converting source data to a channel-modulated signal having pairs of in-phase (I) and quadrature-phase (Q) data in a mobile station, wherein the mobile station includes: encoding the source data to generate at least one data part and a control pant; generating a spreading code to allocate to a channel, wherein each spreading code is selected on the basis of a data rate of the data part and the control part and spreading codes are selected so two consecutive pairs of I and Q data correspond to two points located on same point or symmetrical with respect to a zero point on a phase domain; and spreading the control part and the data part with the spreading code, to generate the channel-modulated signal. The method is capable of improving a power efficiency of a mobile station of a mobile communication system by reducing a peak-to-average power ratio.

A method and system for adaptive control of sub-carriers is useful for increasing frequency diversity gain to improve bit error rate performance in an Interleaved Frequency Division Multiple Access (IFDMA) system. The method includes selecting a combination of a Repetition Factor (RF) and a repetition block size (Q), from possible combinations of a RF and a Q, based on a number of users (Nu) (step 1405). A Spreading Factor (SF), Forward Error Correction (FEC) coding rate (R), or modulation order (M) based on the Nu is then determined (step 1410). Control signals are then provided based on the RF and Q, and based on the SF, R, or M (step 1415).

A code generator and method for generating an orthogonal code for use in the baseband part of a transmitter or transceiver of a telecommunication system. An index conversion unit converts an index (k) into a modified index (j) associated with a corresponding code having a spreading factor greater than one and less than or equal to a maximum spreading factor. A logic unit performs logic operations on bits of the modified index (j) and a counter value (i) to generate a code bit of the orthogonal code. A number of parallel code generators may generate a number of orthogonal codes having respective spreading factors and indices.

In a method for improving capacity for voice users in a communication network and / or a method of avoiding channelization code starvation in the downlink when establishing a voice call with one or more users in the wireless network, two sets of channelization codes may be defined, each adapted for use with a corresponding first spreading factor and second spreading factor. One of the first and second AMR codec sets may be selected based on a comparison of a given number of available channelization codes for a voice call to a threshold, so as to encode voice data for transmission over an air interface.

A transmission apparatus and method for a communication system based on Orthogonal Frequency Division Multiplexing-Code Division Multiplexing (OFDM-CDM). A frequency spreader multiplies symbols to be transmitted by a frequency spreading factor and outputs frequency spread symbols whose number corresponds to the frequency spreading factor. Buffers whose number corresponds to the frequency spreading factor temporarily store the frequency spread symbols in a unit of a predefined number of symbols. A time spreader multiplies parallel frequency spread symbols from the buffers by a time spreading factor and outputs frequency-time spread symbols. An Inverse Fast Fourier Transform (IFFT) processor performs IFFT on the frequency-time spread symbols, and outputs an OFDM symbol. A Guard Interval (GI) inserter inserts a GI into a signal output from the IFFT processor and transmits the signal. The system can obtain complete diversity gain and residual gain due to the effect of a time-varying channel in any channel environment.

The utility model relates to a selection method of transmission rate and modulation code and the device, which comprises the following steps: a lowest and a highest transmission block threshold mapping relation is established to get the spread factors used by each transmission block under a certain time slot number and the corresponding modulation code mode; a power relative value mapping relation is established, and the biggest and the smallest values of the transmission block supported by QPSK and 16QAM modulation modes are acquired according to the dispatching information to determine the transmission block range; the power thresholds needed by the smallest value and the biggest value of each transmission block are calculated; the power threshold value proximal to the power permitted value within the power threshold range is selected, and the lowest and the highest transmission block threshold mapping relation is searched to get the supported biggest transmission block; the data quantity waiting for transmission in current cache is checked to determine the selected transmission block; based on the finally selected transmission block, the transmission format combination is set up, and the emission power value corresponding to the finally selected transmission block is calculated. Based on the base station dispatching information and under the premise of ensuring transmission quality, the utility model selects the highest transmission rate as soon as possible to decide the modulation mode and coding rate.

The invention is intended to provide an adaptive rate adjustment method of an LPWAN internet of things based on a network condition. The adaptive rate adjustment method comprises the steps of receiving uplink frames sent by a terminal; sampling SNR and RSSI values of latest N frames; making a statistics of a packet loss rate according to continuity of frame serial numbers; making a statistics of loads erl of SF (Spread Factor) sub-channels according to occupied channels and used SFs of the terminal; weighting to calculate an expected DR (Data Rate) <mote> of the terminal; when the packet lossrate of the terminal exceeds a packet loss threshold value in an ADR (Adaptive Data Rate) strategy, performing packet loss rate adjustment; when the packet loss rate of the terminal does not exceed the packet loss threshold value in the ADR strategy, performing normal rate adjustment; sending an ADR command to the terminal, and enabling the terminal to adjust a data transmission rate according toan own strategy after receiving the ADR command and make a response; and if a LoRaWAN server does not receive the response, considering that the sending is failed, and repeating to send till the response is received. The adaptive rate adjustment method has the following beneficial effects: the adaptive adjustment can be performed on the data rate of the terminal according to an own network condition including conditions such as a signal quality index, a channel load and the packet loss rate.