Systems and methods for underwater communication using a SISO acoustic channel. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a Bi-SDFE, the at least one transmitted symbol is estimated. The Bi-SDFE may include a SDFE and a time-reversed SDFE that each output bit extrinsic LLRs, which are combined into combined bit extrinsic LLRs. The estimated symbol is then mapped to the combined bit extrinsic LLRs, the result of which is de-interleaved. Iterative bit extrinsic LLRs are generated with a MAP and/or soft-decision decoder using the mapped, combined bit extrinsic LLRs as a priori LLRs for the Bi-SDFE in another iterative estimation. The iterative bit extrinsic LLRs are interleaved and transmitted for use by the Bi-SDFE in another iterative estimation. After a plurality of iterations, a hard decision of the transmitted symbol is generated with the MAP and/or soft-decision decoder.

A method for receiving a signal by integer forcing in a wireless communication system is provided. The method includes receiving one or more signals through a plurality of antennas, filtering the received one or more signals using a forcing matrix, generating codewords by remapping the filtered one or more signals, acquiring a summed codeword by performing a modulo operation on the codewords, decoding the summed codeword, and acquiring original codewords by performing an inversion operation on the decoded summed codeword.

An apparatus, method, computer readable medium, and system are provided to determine whether a non-linear signal impairment is present in a network communication channel. For instance, a computing device may transmit equalization coefficients to a user device to modify future signals generated by the user device. If the equalization coefficients are unable to reduce a signal impairment, the signal impairment may be a non-linear signal impairment. The computing device may generate symbol placements based on signals received from the user device and transmit status messages.

A system for enabling signal penetration into a building includes a first transceiver, located on an outside of the building, for transmitting and receiving signals at a first frequency outside of the building, wherein the signals at the first frequency do not easily penetrate into an interior of the building. A first up/down converter converts between a first version of the signals at the first frequency and a second version of the signals at a second frequency. The first frequency is higher than the second frequency and the signals at the second frequency better penetrate to the interior of the building and overcome losses caused by penetrating into an interior of the building. A second up/down converter converts between the second version of the signals at the second frequency that overcomes the losses caused by penetrating into the interior of the building and a third version of the signals after transmission from the building exterior to the building interior. A router transmits and receives the third version of the signals within the interior of the building.

A circuit in a wireless communications terminal/device and a method is described for reducing an image distortion. By measuring three gain mismatches of I path and Q path of a transceiver, and estimating a value of an IQ mismatch coefficient based on the three gain mismatches; and applying a measurement adjustment to the I path or the Q path based on the value of the IQ mismatch coefficient, the image distortion is reduced.

A system for enabling signal penetration into a building comprising a receiver located on an outside of the building for receiving millimeter wave signals. At least one frequency downconverter for downconverts the received millimeter wave signals to a frequency level that overcomes losses occurring when the millimeter wave signals are transmitted from the outside the building to an interior of the building. Transceiver circuitry transmits the downconverted millimeter wave signals from the outside the building to the interior of the building. At least one frequency upconverter upconverts the received downconverted millimeter wave signals from the frequency level that overcomes losses occurring when the millimeter wave signals are transmitted from the outside the building to the interior of the building. A second transceiver transmits the upconverted millimeter wave signal in a second format to wireless devices within the building.

A multi building block architecture may be configured to generate a waveform (a target wideband signal) for use in a wireless communication system, where the waveform supports a variety of baseband signals. The task of generating a target wideband signal can be divided into several tasks, each task relating to the generating of one of a plurality of sub-carrier bands. Each of the sub-carrier bands (sub-bands) may be generated by one of the sub-band building units included in the sub-band building blocks of the architecture. Several sub-bands may be formed, by a sub-band group building block, into a sub-band group. Multiple sub-band groups may be formed, by a wideband building block, into the target wideband signal.

A system for enabling signal penetration into a building includes a first transceiver, located on an outside of the building, for transmitting and receiving signals at a first frequency outside of the building, wherein the signals at the first frequency do not easily penetrate into an interior of the building. A first up/down converter converts between a first version of the signals at the first frequency and a second version of the signals at a second frequency. The first frequency is higher than the second frequency and the signals at the second frequency better penetrate to the interior of the building and overcome losses caused by penetrating into an interior of the building. A second up/down converter converts between the second version of the signals at the second frequency that overcomes the losses caused by penetrating into the interior of the building and a third version of the signals after transmission from the building exterior to the building interior. A router transmits and receives the third version of the signals within the interior of the building.

The present invention relates to a 5th-generation (5G) or pre-5G communication system, which is to be provided for supporting a higher data transmission rate after the 4th-generation (4G) communication system, such as long term evolution (LTE). The present invention provides a method for receiving a signal in a multi-carrier system, the method comprising the steps of: performing, with respect to an input signal, a waveform pre-processing operation on the basis of at least one of an equalizing operation and a filtering operation; checking whether the waveform pre-processed signal is a Gaussian proximity signal; and performing soft-de-mapping with respect to the waveform pre-processed signal on the basis of a result of the checking.

Methods, systems, and devices are described for wireless communications. An example method includes identifying one of at least two channel quality indicator (CQI) tables. The method also includes generating, based at least in part on the identified CQI table, a CQI value for a wireless channel. Another example method includes receiving CQI data for a wireless channel. The method also includes identifying one of at least two CQI tables to use to identify a CQI value. Additionally, the method includes identifying the CQI value based at least in part on the received CQI data and the identified CQI table.