Techniques for blind distributed multi-user MIMO enable simultaneous decoding of multiple concurrent wireless transmissions without the need for coordination between wireless devices or a measurement phase. Wireless devices are permitted to transmit independently and at arbitrary times. Concurrent transmissions from wireless devices superimpose in the wireless channel and are received at various base stations. The base stations forward received data samples to a central entity (e.g., a cloud computing service), which uses known preambles to reliably estimate CFOs and channels between the transmitting devices and the receiving base stations while simultaneously recovering the data samples of the individual data streams.

A method and apparatus for enhancing channel estimation by using a binary tree based PDCCH search space in a new radio wireless communication system is disclosed. For example, a UE may identify an aggregation level profile having an aggregation level value for one or more aggregation levels, wherein each aggregation level corresponds to a respective number of resources to use for decoding a PDCCH, determine one or more decoding candidates for the UE from among a plurality of available decoding candidates defined as nodes in a binary tree for a search space based on the aggregation level profile, determine respective CCEs corresponding to each of the one or more decoding candidates, each respective CCE including one or more REGs, and performing channel estimation for each of the respective CCEs for use in demodulating and decoding downlink control information for the UE in the PDCCH.

Methods, systems, and devices for wireless communications are described. A base station may identify time and frequency resources for a physical downlink shared channel (PDSCH) to be transmitted to a user equipment (UE) in a first transmission time interval (TTI). The base station may transmit configuration information for a control channel search space set in a second TTI. The second TTI may precede the first TTI. The configuration information may include an indication of an absence of a physical downlink control channel (PDCCH) transmission to send in the control channel search space set indicating the identified time and frequency resources for the PDSCH, and a set of time and frequency resources for the control channel search space set. The UE may receive the configuration information and identify the time and frequency resources allocated for the PDSCH in the second TTI, and receive the PDSCH transmission in the second TTI.

A method for receiving a PDCCH signal by a terminal in a wireless communication system according to one embodiment of the present invention may comprise the steps of: determining the number of CCEs for channel estimation and the number of times of blind-decoding related to multiple search space sets that the terminal needs to monitor during one slot; when the determined number of times of the blind-decoding exceeds a blind-decoding limit or the determined number of the CCEs exceeds a channel estimation limit, dropping at least one PDCCH candidate among PDCCH candidates included in the multiple search space sets; and attempting to detect a PDCCH signal on the basis of remaining PDCCH candidates which have not been dropped among the PDCCH candidates, wherein, in the dropping of the at least one PDCCH candidate, the terminal switches between the multiple search space sets in a round-robin scheme while dropping the at least one PDCCH candidate until both the blind-decoding limit and the channel estimation limit are reached.

The communication method includes: sending, by a CMTS (cable modem terminals stem), a reference signal within a first time period by using a valid subcarrier in a first spectrum, where the first time period is a time period within which none of CMs (cable modems) connected to the CMTS sends a signal in the first spectrum; performing, by the CMTS based on an interfering signal received by the CMTS within the first time period, channel interference estimation on a channel that is used during signal reception of the CMTS and that occupies the first spectrum, where the interfering signal is a signal obtained after the reference signal passes through the channel; and canceling, by the CMTS based on a result of the channel interference estimation, interference from a first signal received by the CMTS to a second signal received by the CMTS.

A method by which a terminal receives downlink control information in a wireless communication system includes: receiving a reference signal for a control channel by a search space set in a control resource set; and receiving downlink control information of the control channel on the basis of the reference signal. The search space includes a plurality of control channel candidates respectively corresponding to one or at least two CCEs according to an aggregation level, the one or at least two CCEs respectively include a plurality of REGs, and the terminal performs blind detection for each of the plurality of control channel candidates, and it can be assumed that a reference signal for a predetermined control channel candidate, for which blind detection is currently being performed, is mapped to a first REG firstly located in a time domain among REGs included in the predetermined control channel candidate.

A method for receiving downlink control information by a terminal in a wireless communication system according to an embodiment of the present invention may comprise the steps of: performing blind detection of a group-common physical downlink control channel (PDCCH) in a common search space (CSS) having a plurality of PDCCH candidates; and acquiring downlink control information (DCI) indicating a slot format from the group-common PDCCH acquired through the blind detection, wherein, in the blind detection of the group-common PDCCH, the terminal attempts to selectively detect the group-common PDCCH for only a PDCCH candidate at a predetermined position in the CSS having the plurality of PDCCH candidates.

Methods, systems, and devices for wireless communication are described. In some cases, due to blind decoding and channel estimation (CE) limits, one or more user equipment (UE) specific search sets may be pruned for blind decoding and/or CE purposes. For instance, after hashing a set of common decoding candidates to control channel elements (CCEs) within the control region, the UE specific search sets may be pruned so as to conform to the blind decode limitation, since a common search space has already occupied a portion of the total blind decode limit. Following pruning, the UE may hash the sets of UE-specific decoding candidates associated with the one or more UE specific search sets to CCEs within the control region. The UE may further prune UE specific search sets, based on CE limits, while reusing CE for overlapping hashed locations.

The disclosure provides a subspace-based blind identification algorithm of an ocean underwater acoustic channel for multi-channel fir filter, which adopts a technical solution that a channel impulse response coefficient is calculated by quadratic minimization. The disclosure has beneficial effects that estimation precision can be met when using a proper number of samples, and especially when a few noise vectors are used for estimating channel parameters, so that calculation amount is greatly reduced.

Methods, systems, and devices for wireless communication are described. In some cases, due to blind decoding and channel estimation (CE) limits, one or more user equipment (UE) specific search sets may be pruned for blind decoding and/or CE purposes. For instance, after hashing a set of common decoding candidates to control channel elements (CCEs) within the control region, the UE specific search sets may be pruned so as to conform to the blind decode limitation, since a common search space has already occupied a portion of the total blind decode limit. Following pruning, the UE may hash the sets of UE-specific decoding candidates associated with the one or more UE specific search sets to CCEs within the control region. The UE may further prune UE specific search sets, based on CE limits, while reusing CE for overlapping hashed locations.