142 results about "Hierarchical modulation" patented technology

A broadcasting base station device transmits broadcast signals modulated by a hierarchical modulation scheme to a mobile terminal device. A hierarchical modulation setup section compares the reception quality of the broadcast signals at the location of the mobile terminal device to predetermined reference quality. Based on the result of the comparison, the hierarchical modulation setup section specifies a hierarchical modulation scheme. For example, the constellation in each quadrant is reduced or enlarged. Accordingly, the broadcasting base station device can transmit optimal broadcast signals that match with actual reception quality to each mobile terminal device.

The present invention employs hierarchical modulation to simultaneously transmit data over different modulation layers using a carrier RF signal. Each modulation layer may be of a higher or lower order than the other modulation layers. Certain embodiments of the present invention may transmit different information on the different modulation layers. Other embodiments of the present invention may use the different layers for processing different information streams.

Dynamic channel estimation thresholds allow for determining optimal threshold values for channel estimation in a layered-modulation wireless communication system. A channel estimation threshold can be used to remove or otherwise filter out channel estimate components that may be significantly influenced by noise. The channel estimation threshold value can be used to generate a refined channel estimate that is used in decoding multiple layers of a layered modulation signal. The channel estimation threshold value can be varied based on the performance of the various signal layer decoders. The adaptive channel estimation threshold provides for decoding a base layer based on an optimal threshold value for the base layer; determining an error rate associated with decoding the base layer; and using an optimal threshold value for an enhancement layer in a channel estimation algorithm if the error rate is lower than a predetermined level.

The present invention provides a method, receiver and transmitter for use in a SDAR system. The method involves generating a first modulated signal based on first input data. Additional modulation is superimposed on the first modulated signal based on additional input data, being spread across a plurality of symbols in the first modulated signal in a predetermined pattern to generate a modified signal which is then transmitted. The modified signal is decoded by performing a first demodulation of the first modulated signal then additional demodulation is performed to obtain additional input data. The superimposing step uses a plurality of offset sequence values to add the additional modulation to the first modulated signal. The offset sequence may appear as a pseudo-random distribution of offset sequence values, and may include at least one zero offset value. Alternatively, the additional modulated signal may be a fromed as a direct sequence spread spectrum modulation and the offset sequence appearing as a pseudo-noise distribution. A Hadamard matrix sequence may be used as the direct sequence code.

Methods and apparatuses for maximizing power and spectral efficiencies in a wireless communication system are disclosed. The invention is particularly useful for layered modulation applications because power levels for such applications are relatively high. A layered modulation signal comprises an upper and a lower layer signal that interfere with each other within the same frequency band such that the upper layer signal can be demodulated directly from the layered modulation signal, and the lower layer signal can be demodulated after subtracting the first layer signal from the layered modulation signal. The invention applies one or more of the following four signal schemes in a communication signal including varying the symbol rate (rather than the code rate), reducing or eliminating the guard band, reducing excess signal bandwidth and employing layered modulation within the guard band of the legacy signal.

In accordance with various aspects of the invention, there is being provided a method and apparatus for transmitting, and a method and apparatus for receiving a digital broadcast signal including a hierarchical modulation having a high priority stream and a low priority stream. The content to be received or transmitted in encoded into two stream so that a first stream is configured to be transmitted or received with the high priority stream, and a second stream to be transmitted/received with the low priority stream is configured to contain additional information for increasing the bitrate of the first stream.

Techniques for measuring the carrier to noise ratio (CNR) in a received digital signal are disclosed. The methods can operate on a received digital signal, such as a layered modulation signal used in a satellite television system. The CNR measurement can be made at the output of a carrier recovery loop or a timing recovery loop in a demodulator. Alternately, the CNR measurement can be made when the received signal is digitized in an analog to digital (A/D) converter at base-band by the demodulator.

Methods, systems, and devices are described for hierarchical modulation and interference cancellation in wireless communications systems. Various deployment scenarios may be supported that may provide communications on both a base modulation layer as well as in an enhancement modulation layer that is modulated on the base modulation layer, thus providing concurrent data streams that may be provided to the same or different user equipments. Various interference mitigation techniques may be implemented in examples to compensate for interfering signals received from within a cell, compensate for interfering signals received from other cell(s), and/or compensate for interfering signals received from other radios that may operate in adjacent wireless communications network.

An approach is provided for supporting signal acquisition and frame synchronization in a digital broadcast system utilizing Low Density Parity Check (LDPC) codes. Hierarchical modulation is utilized to provide backward compatibility, whereby the lower layer signal is encoded using LDPC coding. A signal is received, whereby the signal is modulated according to the hierarchical modulation scheme including an upper layer and a lower layer. The signal includes a data pattern and a coded frame. The dependency of the received signal on the upper layer modulation is removed. The modulation removed signal is correlated with multiple predetermined data patterns to determine the data pattern of the signal. The code rate of the coded frame is derived based on the determined data pattern. The above arrangement is particularly suited to a digital satellite broadcast system.

A multicarrier transmitter and a multicarrier receiver both enabling improvement of the reception characteristic of hierarchical modulation multiplex communication. A base station (100) transmits a multicarrier signal which is a superposition of a modulated signal addressed to a far user and a modulated signal addressed to a near user and modulated with a modulation multivalued number different from that of the modulated signal addressed to the far user. The base station (100) comprises a DFT section (120), an S/P section (125), and a combining section (145). The DFT section (120) separates the modulated signal addressed to the far user into signals in frequency ranges for each symbol. The S/P section (125) serial/parallel-transforms the modulated signal addressed to the near user to generate N1 parallel signals. The combining section (145) combines the N1 frequency components generated by the DFT section (120) and the N1 parallel signals. Since the far user receiver can change the modulated signal addressed to the near user into white noise by IDFT, the far user receiver can demodulate the modulated signal addressed to the far user with high accuracy. The near user receiver can acquire the signal addressed thereto with high accuracy by subtracting the modulated signal addressed to the far user, which is an interference signal, from the received signal.

There is provided a method for hierarchical modulation relating to a first signal, a second signal, and an original constellation having a plurality of symbols in a non-uniform 8 Phase-Shift-Keying (PSK) configuration. Quadrature-Phase-Shift-Keying (QPSK) modulation is used for the first signal and Binary-Phase-Shift-Keying (BPSK) modulation is used for the second signal. The method includes the step of replacing at least some of the plurality of symbols with at least one radial-type QPSK-BPSK constellation.

A method and apparatus for transmitting and receiving a coded signal having an upper layer signal and a lower layer signal is disclosed. The method comprises the steps of combining the upper layer signal and the lower layer signal, encoding the combined upper layer signal and lower layer signal, delaying the upper layer signal, modulating the delayed upper layer signal, modulating the lower layer signal, transmitting the delayed upper layer signal and transmitting the lower layer signal. The apparatus comprises an encoder, for encoding a combined upper layer signal and lower layer signal, a delay, communicatively coupled to the encoder, for delaying the upper layer signal, a first modulator, for modulating the delayed upper layer signal, a second modulator, for modulating the lower layer signal, a transmitter, communicatively coupled to the first modulator, for transmitting the delayed upper layer signal, and a second transmitter, communicatively coupled to the second modulator.

A communication system and method of communicating signals to a plurality of different types of receivers is provided. The communication system includes at least one transmitter that transmits a high priority signal and a low priority signal that are hierarchically modulated and transmitted as a single frequency network. At least one satellite receives and re-transmits at least one of the high priority and low priority signals. At least one of the plurality of receivers include a processor that performs the steps of storing the hierarchically modulated signal, demodulating the high priority signal from the hierarchically modulated signal, decoding the demodulated high priority signal, re-encoding the high priority signal, and processing the stored hierarchically modulated signal based upon the re-encoded high priority signal.

System(s) and method(s) are provided to transmit simultaneously a first and a second communication channel in a single-carrier waveform format with disparate error rate requirements. First channel and second channel are coded individually to form an alphabet for a first and second constellation. Prior to transmission, bits of information of the first and second channels are modulated with a hierarchical modulation constellation is generated through a combination of a first a second constellation; each constellation is assigned a configurable weight (e.g., a ''hierarchic weight'') that is expressed in terms of a configurable energy ratio. The energy ratio determines the resilience of bits associated with the first and second channel. Bit mapping within the first and second constellation provides redundancy to mitigate error rate within each quadrant of the hierarchical constellation. Hierarchical modulation of more than two channel can be accomplished through the same principal of individual coding and constellation composition.

This invention provides a channel interlacing method and a system in a handheld TV system, in which, the method includes: A, carrying out LDPC coding to input signal source bit streams to output LDPC coding blocks, B, carrying out bit interlacing among the blocks of LDPC, C, carrying out constellation mapping to the interlaced bits to generate constellation points, D, interlacing and mapping the points onto a time frequency plane of a multi-frame including multiple data frames to get an even better time diversity result , at the same time, bit information in a LDPC coding block can be scattered to irrelated data subcarriers by interlacing among LDPC coding blocks and interlaced mapping of constellation and different modulation steps can be processed together.

A receiver recovers local service data symbols from first Orthogonal Frequency Division Multiplexed (OFDM) symbols in the presence of second OFDM symbols. The second OFDM symbols carry national broadcast data symbols and modulated on to the sub-carriers of the second OFDM symbols using a first modulation scheme. The first OFDM symbols carry the national broadcast data symbols and the local service data symbols from a local insertion pipe and modulated on to the sub-carriers of the first OFDM symbols using a second modulation scheme. The receiver comprises an OFDM detector which includes an equalizer to recover local service modulated sub-carriers of the second modulation scheme.

An apparatus and a method of transmitting hierarchically modulated signals are provided. The present invention includes: a basic layer symbol generator generating a first layer signal; an enhancement layer symbol generator generating a second layer signal synchronized with the first layer signal and having different signal power; and a hierarchical modulator hierarchically modulating the first layer signal and the second layer signal, wherein the enhancement layer symbol generator performs constellation rotation rotating bundles configured as constellation points formed by the second layer signal based on constellation points of the first layer signal by a predetermined angle. According to the exemplary embodiment of the present invention, it is possible to improve the receiving performance of the second layer signals by applying the constellation rotation technology to the second layer signals in regards of the signal transmission system using the hierarchical modulation technology.

Disclosed is a novel cooperative communication strategy jointly using symbol-level random network coding and hierarchical modulation in order to effectively minimize packet error rate in error prone wireless networks. The source (or sender) broadcasts random network coded symbols with hierarchical modulation to the relays and the destination (or receiver). In following time slots, the relays, which have successfully decoded the original packet, transmit additional random network coded symbols to the destination. By applying the present disclosure into a multi-hop relay consumer device network, which comprises a set of consumer devices, error free transmission with high efficiency can be achieved.

The present invention relates to the field of digital information transmission technology. The hierarchical block product code (BPC) error correcting, encoding and modulation method includes: coding the input data code stream with different priority level in separate BPC code to obtain BPC stream, mapping the BPC stream based on definition to different bits of planisphere symbol of set modulationmode to obtain hierarchical modulation signal output with different antijamming capability. The present invention has the advantages of simple embodiment, more priority levels, powerful error correcting capacity and high reliability, and may be used in ground digital TV broadcasting system and other fields.

A method is provided for enhancing a legacy satellite digital radio audio service (SDARS) by overlaying a hierarchically modulated data stream on a base layer (legacy) data stream and improving the synchronization of the received signal in which an overlay layer frame is synchronized to a base layer frame. The base layer frame includes additional data that is used to synchronize the receivers to demodulate and decode the overlay layer and the base layer. The additional data is modulated using a technique that aids the receiver in synchronizing the received signal that is different from the overlay layer.

The present invention involves a method for transmitting data using an orthogonal frequency division multiplex (OFDM) transmission system, such as over a terrestrial network used in satellite digital audio radio. A OFDM signal is generated based on first input data. A variation is introduced in the OFDM signal based on second input data to generate a modified OFDM signal which is transmitted. The modified OFDM signal is decoded by performing a demodulation of the modified OFDM signal then a first and second detection to obtain the first input data and the second input data. The introduction of a variance may include introducing an additional phase offset across adjacent OFDM sub-carriers, across adjacent OFDM symbols, an additional phase offset in the OFDM signal, an additional amplitude offset in the OFDM signal, an additional amplitude augmentation in the OFDM signal, and/or a second variation in the first OFDM signal based on third input data.

A receiving device is provided to coordinate transmissions from a first transmitting device and from a second transmitting device of a plurality of transmitting devices to the receiving device in a communication network. The transmissions are coordinated by sending, from the receiving device, a first instruction to the first transmitting device to transmit a first signal according to first transmission characteristics, wherein the first signal comprises a base layer data stream, sending, from the receiving device, a second instruction to the second transmitting device to transmit a second signal according to second transmission characteristics, wherein the second signal comprises an enhanced layer data stream, receiving, at the receiving device, a hierarchical modulation signal comprising the first signal and the second signal being simultaneously transmitted, and separating, at the receiving device, the base layer data stream and the enhanced layer data stream from the received hierarchical modulation signal.

The present invention provides a receiver for use in a SDAR system, the receiver including a receiving unit having satellite signal detection means for detecting a transmit signal transmitted from a satellite, the transmit signal produced when the transmitter modulates a primary data stream with a secondary data stream on a carrier wave associated with the satellite; and at least one demodulator coupled to the receiving unit and configured to demodulate the transmit signal.

A technique for demodulating secondary data from a hierarchically modulated signal includes a number of steps. A gray coded eight phase shift key (8-PSK) hierarchically modulated signal is received that includes primary data and secondary data. An imaginary portion of the signal is determined and a real portion of the signal is determined. An absolute value of the real portion of the signal may then be subtracted from an absolute value of the imaginary portion of the signal to provide the secondary data. The gray coded 8-PSK hierarchically modulated signal may be a uniform gray coded 8-PSK hierarchically modulated signal or a non-uniform gray coded 8-PSK hierarchically modulated signal.