This disclosure describes systems, methods, and devices related to a trigger-based null data packet (NDP) for channel sounding system. A device may send a trigger frame to a group of station devices, the group of station devices including a first station device, the trigger frame indicating a high efficiency (HE) long training field (HE-LTF) mode and a guard interval duration. The device may identify a HE trigger-based (TB) null data packet (NDP) received from the first station device, the HE TB NDP including a first packet extension field, wherein the HE TB NDP is associated with the HE-LTF mode and the guard interval duration indicated in the trigger frame. The device may send a downlink NDP including a second packet extension field, a second HE-LTF mode, and a second guard interval duration. The device may determine channel state information based on HE TB NDP received from the first station device.

An equalizer that has a wide variable gain range and that can implement equalization for a communication medium such as on-board wiring or a cable having various wiring lengths. The equalizer includes a core circuit and a source follower connected to a subsequent stage of the core circuit. The core circuit includes a differential pair including a first transistor and a second transistor, and a zero point generation circuit connected between a second terminal of the first transistor and a second terminal of the second transistor. The source follower includes a third transistor and a fourth transistor, a variable bias current source is connected to the third and fourth transistors, and a load in which a capacitive element and a resistor element are connected in series via a switching element is connected to wiring that connects the third and fourth transistors to an output terminal.

A feed forward equalizer including a first set of filter taps having a first set of filter tap coefficients to be adapted and a second set of one or more filter taps having one or more filter tap coefficients to be constrained. The feed forward equalizer includes an adaptation component to determine a set of adapted filter tap coefficient values corresponding to the first set of filter tap coefficients and a constraint function component to determine a constrained filter tap coefficient value for the second set of the one or more filter taps having the one or more filter tap coefficients to be constrained using a constraint function based on at least a portion of the set of adapted filter tap coefficient values. The feed forward equalizer generates, based at least in part on the constrained filter tap coefficient value, an equalized signal including a set of estimated symbol values.

Some implementations describe a method including: receiving, by multiple receivers of multiple gateways of a ground receiver system, from multiple transmitters of a satellite over a downlink of a LoS MIMO feeder link, multiple RF signals; obtaining, at the ground receiver system, from the RF signals, preamble signals and pilot signals including first sequences of pilot symbols associated with second sequences of pilot symbols transmitted by the transmitters; estimating, based on the first sequences of pilot symbols and second sequences of pilot symbols, first channel state information (CSI) of the pilot signals; estimating, using the first CSI, frequency offsets and phase offsets of links between the receivers and the transmitters; adjusting, based at least on the frequency offsets and the phase offsets, the preamble signals to obtain adjusted preamble signals; and estimating, at the ground receiver system, using the adjusted preamble signals, second CSI of the downlink.

A method for receiving data by a terminal in a wireless communication system according to the present document comprises: receiving a channel signal and a reference signal (RS) from a base station; and generating a sequence by filtering the RS, and decoding the channel signal on the basis of the generated sequence, wherein the filtering is zero forcing (ZF) filtering, and the decoding of the channel signal is a selection of one parameter from among parameter sets generated in accordance with a colored-noise machine learning process.

A feed forward equalizer including a first set of filter taps having a first set of filter tap coefficients to be adapted and a second set of one or more filter taps having one or more filter tap coefficients to be constrained. The feed forward equalizer includes an adaptation component to determine a set of adapted filter tap coefficient values corresponding to the first set of filter tap coefficients and a constraint function component to determine a constrained filter tap coefficient value for the second set of the one or more filter taps having the one or more filter tap coefficients to be constrained using a constraint function based on at least a portion of the set of adapted filter tap coefficient values. The feed forward equalizer generates, based at least in part on the constrained filter tap coefficient value, an equalized signal including a set of estimated symbol values.

A distributed unit (DU) may include a transceiver configured to communicate with a plurality of radio units (RUs) that are configured to serve a plurality of user equipments (UEs). The DU may include a processor configured to determine RU precoding parameters for UEs served by a first RU set from the plurality of RUs based on estimated channel parameters for communication channels between the first RU set and at least one of interfering UEs served by other RUs from the plurality of RUs; to encode information indicating the determined precoding parameters for downlink transmissions to the first RU set and determine DU precoding parameters for downlink transmissions to the UEs served by the first RU set based on the determined RU precoding parameters; and/or precode communication signals based on the determined DU precoding parameters.

This disclosure describes methods, apparatus, and systems related to a channel estimation field (CEF) for various standards, for example, the 802.11ay standard, for single carrier (SC) MIMO channel estimation. In one embodiment, the CEF can use Golay complementary sequences. In another embodiment, the Golay complementary sequences can be defined similar to Golay complementary sequences definitions that can be found in various legacy standards, for example, the legacy 802.11ad standard. Various embodiments of the disclosure can allow channel estimation in the time domain and/or frequency domain, having small or negligible inter-stream interference. Various embodiments of the disclosure can enable an extendable structure for various M×N MIMO configurations, where M and N are positive integers.

A method for transmitting and receiving a signal of a terminal, according to an embodiment of the present invention includes the steps of: receiving a signal from a base station; calculating an expected value of the signal to interference plus noise ratio (SINR) based on the received signal; and choosing a beamforming method based on the expected value of SINR. The present invention can provide a method and an apparatus which apply adaptive ICIC in CoMP environment so as to maximize WSR with reduced complexity of calculation, thus having a performance comparable to that determined by the conventional method, and providing the user with a smooth communication environment with improved quality. Furthermore, a terminal communicating with a base station chooses a desirable beamforming technique with reduced complexity so as to decrease the complexity of the system and to provide higher power efficiency with a faster calculation speed. Besides, it is possible for a base station to readily choose the user group and the beamforming technique group with the optimum communication environment.

Embodiments herein provide a method of estimating channel states of a plurality of user equipments (UEs) in a single instance. The method includes receiving pilot samples from the plurality of UEs. The method includes selecting a predetermined number of tones, wherein the channel associated with each UE across the selected pre-determined number of tones is same. The method includes collecting the received pilot samples from each pilot symbol and stacking the received pilot samples as a vector. Further, the method includes constructing a matrix. The matrix includes known pilot values used by each UE. Furthermore, the method includes estimating channel states of the plurality of UEs by applying a filter on the vector formed from the received pilot samples. The number of channel states to be estimated is reduced by selecting the pre-determined number of tones.