60 results about "Mobile communication channels" patented technology

A test signal generator at a transmitter station and a facsimile generator at a receiver station go through an acquisition and tracking process which aligns the two signals, removing errors in the time base of generation, the frequency offset of generation and the time of arrival, so that a logical processor can compute the frequency transfer function of the entire propagation path for use in an adaptive, concurrently sent communication signal. The frequency transfer function is conveyed back to the transmit end via a control channel permitting an adaptivity function at the transmit end to influence subsequent selection of communication parameters, among which are typically transmitted data rate, selection of modulation, selection of forward error correcting coding, and selection of frequency band for transmission. The same measurement is conveyed to an adaptivity function at the receive end for use in the communications receiver to select demodulator variables such as gain control, and equalization of amplitude and phase, versus frequency. The adaptivity function also permits interspersing of reverse-direction communications over the same frequency bands in a time-share mode between forward-direction and reverse-direction communication with the measurement signals having to be transmitted in only one direction. An alternate embodiment invention of this type is described which is additionally useful for mobile communications channels. Another variation embodiment is described for pure propagation measurements only, absent conveyance of end-user information.

A test signal generator at a transmitter station and a facsimile generator at a receiver station go through an acquisition and tracking process which aligns the two signals so that a logical processor can compute the frequency transfer function of the entire propagation path for use in an adaptive, concurrently sent communication signal. The frequency transfer function is conveyed back to the transmit end via a control channel permitting an adaptivity function at the transmit end to influence subsequent selection of communication parameters, among which are typically transmitted data rate, selection of modulation, selection of forward error correcting coding, and selection of frequency band for transmission. The same measurement is conveyed to an adaptivity function at the receive end for use in the communications receiver to select demodulator variables such as gain control, and equalization of amplitude and phase, versus frequency. The adaptivity function also permits interspersing of reverse-direction communications over the same frequency bands in a time-share mode between forward-direction and reverse-direction communication with the measurement signals having to be transmitted in only one direction. An alternate embodiment invention of this type is described which is additionally useful for mobile communications channels. Another variation embodiment is described for pure propagation measurements only, absent conveyance of end-user information.

The invention relates to the technical field of mobile communication channel coding, in particular to a method and a device for generating code rate compatible with quasi-cyclic low density parity check (LDPC) codes. The method comprises the following steps that: the degree distribution of high-code-rate quasi-cyclic LDPC codes and the low-code-rate requirement of a system are obtained, and the degree distribution of low-code-rate quasi-cyclic LDPC codes is designed; variable nodes to be expanded and check nodes to be resolved in the high-code-rate quasi-cyclic LDPC codes in the low-code-rate quasi-cyclic LDPC code constructing process are determined; check matrixes of the low-code-rate quasi-cyclic LDPC codes are constructed on the basis of a constructing method and the limitation of the low-code-rate quasi-cyclic LDPC codes on the check matrix check part structure; and the check bits of the obtained quasi-cyclic LDPC codes are interwoven, and then, code rate compatible codes are obtained through residue deletion. The embodiment of the invention also provides the device for implementing the method and provides hybrid automatic repeat request (HARQ) schemes based on the code rate compatible quasi-cyclic LDPC codes.

A transceiver system employing vector feedback to linearize the transmitter over a narrowband channel to support concurrent low-rate subchannels, each providing a low bit error rate (BER). Symbols in each subchannel are transmitted at a rate sufficiently slow to avoid multipath errors, thereby spreading each signal component across the entire channel bandwidth to eliminate any remaining discrete non-linearity. The system provides for generating constellations of signal states that can be optimized for both phase and amplitude to represent symbols within existing narrowband mobile communications channels. Symbols are transmitted at a rate sufficiently slow in each subchannel to decorrelate multipath interference at the receiver, thereby better discriminating adjacent symbol states. This transceiver is particularly useful for mobile environments, although it applies equally well to stationary environments. Data sequences may be transferred at up to 110 kbits / sec within a standard 25 kHz RF channel for slow scan video applications.

A mobile implementation channel supports the processing of a request for requested information for a customer of a business. The request may be generated through a wireless terminal and include a customer identification of the customer. Profile information about the customer may then be accessed and the user identification mapped to a device type of the customer. When the profile information indicates that the customer should be invited to interact with a representative the business, an invitation message is directed through the corresponding mobile communication channel type to the customer's device of the customer. The invitation message may include contact information and the requested information. The contact information may then be utilized to establish a communications connection between the customer and the representative of the business. Otherwise, only the requested information is directed through the mobile communication channel type to the customer's device.

The invention provides a method for retransmitting broadcasting data of a single frequency network, which comprises the steps that: step S102, a terminal retransmits request signals towards a base station under a preset condition at a preset time by the upstream period of a first mobile communication spectrum; step S104, the base station sends control signals required by data retransmission to the terminal by the downstream period of the first mobile communication spectrum; step S106, the terminal receives retransmission data sent by a second mobile communication channel according to the control signals. Therefore, the invention solves the problems of spectrum resource waste existing in the data retransmission in the present MBMS SFN network and can retransmit broadcasting data on the SEN network to the terminal which requires retransmission by using the two-way link of the mobile communication base station without stopping the present MBMS SFN service broadcasting.

The invention discloses a Doppler estimation and compensation method for sparseness detection of an orthogonal multi-carrier underwater acoustic mobile communication channel. Aiming at the problem caused by limited frequency domain response resolution in a complex multipath time-varying channel environment, the method utilizes the principle that the Doppler distortion signal subcarrier orthogonality is not changed, extracts a pilot subcarrier frequency domain response by local subcarrier Discreet Fourier Transform (DFT), calculates channel impulse responses and sparseness thereof of the signalunder different Doppler compensation conditions, and selects a decompression signal of the compression factor estimation result with the largest channel sparseness, thereby realizing the mobile underwater acoustic communication in the complex multipath time-varying channel environment. The method improves the Doppler estimation accuracy, which is mainly due to the frequency domain resolution accuracy. The carrier demodulation matrix of the method is generated by calcualting a Doppler compression factor, and the Doppler is used to demodulate the carrier matrix of each subcarrier with a relatively higher resolution, so that the Doppler compensation effect is better.

Aspects of the present disclosure generally relate to systems and methods for extending chat capabilities of traditional computer-to-computer chat systems to mobile devices. As will be generally understood, chat sessions typically allow users and chat agents to type and send / receive messages through a chat system. According to one aspect, such a mobile consumer messaging system (MCMS) utilizes existing mobile communication channels to interface with existing traditional chat systems. Specifically, in various embodiments of the MCMS, chat agents using existing, traditional chat systems are able to participate in chat sessions with end users through the users' mobile devices without specific modifications to the existing chat system. Further, according to one embodiment, chat agents utilize a single chat platform to participate in chat sessions with end users through the end users' mobile devices as well as with various other users utilizing a traditional chat system on a computer.