Patent Description:
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to demodulator search spaces in wireless communications.

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.

For example, a fifth generation (<NUM>) wireless communications technology (which can be referred to as <NUM> new radio (<NUM> NR)) is envisaged to expand and support diverse usage scenarios and applications with respect to current mobile network generations. In an aspect, <NUM> communications technology can include: enhanced mobile broadband addressing human-centric use cases for access to multimedia content, services and data; ultra-reliable-low latency communications (URLLC) with certain specifications for latency and reliability; and massive machine type communications, which can allow a very large number of connected devices and transmission of a relatively low volume of non-delay-sensitive information.

In some wireless communication technologies, such as <NUM> NR, devices, including user equipment (UE), can use advanced receivers having specific demodulators that consider a defined search space over a constellation for generating log likelihood ratios (LLRs) for demodulating received signals. One example of such a demodulator can include a per-stream recursive demapping (PSRD) demodulator.

The scope of the invention is defined and limited by the appended set of independent claims. Further embodiments are defined by the appended set of dependent claims.

According to one or more aspects of the invention, a higher spectral efficiency, increased power savings and reduced computational complexity is achieved at the UE by moving the computational load of calculating the search space size of the PSRD demodulator to the base station, so that there are no additional calculations at the UE.

The following prior art documents are considered to be relevant for the present application:.

The disclosed aspects will hereinafter be described in conjunction with the appended drawings, in which:.

The described features generally relate to configuring demodulator search space in wireless communications. For example, in wireless communication technologies such as fifth generation (<NUM>) new radio (NR), devices can use advanced receivers having certain types of demodulators that use search spaces for generating log likelihood ratios (LLRs) for demodulating received signals. One example of such a demodulator can include a per-stream recursive demapping (PSRD) demodulator. A PSRD demodulator can determine or utilize a search space for searching over a constellation for generating the LLRs, as described further herein. Typically, the device that has the demodulator can determine a size of the search space, which is also referred to herein as the search space size, based on measured metrics, which may include channel quality or reference signal received power or quality metrics. Aspects described herein relate to performing search space size selection at a different node, such as a node transmitting signals to the receiving device that has the demodulator.

In <NUM> NR, for example, where a user equipment (UE) includes the demodulator and receives signals, a base station or other node with more processing resources than the UE may configure the search space size for the UE demodulator. For example, the base station can determine the search space size based on metrics received from the UE, which may include a latest received sounding reference signal (SRS), a determined delay from receiving the latest SRS, channel state information (CSI) reports from the UE, or other metrics reported by the UE. The base station can use this information to determine an expected search space size to be used by the UE demodulator and can signal the search space size, or one or more parameters for determining the search space size, to the UE. The UE can accordingly determine the search space size and use the search space size for the demodulator in generating LLRs for demodulating received signals (e.g., signals received from the same base station or other nodes).

Using a different node, such as a base station or other node with higher processing power or more readily available processing resources than a UE, to configure the search space size, may allow for more powerful resource intensive search space size determination. For example, the different node can use artificial intelligence (AI)-based search space size determination based on the metrics provided by the UE. Using different or more intensive search space size determination at the different node, in this regard, can allow for more accurate or intuitive search space size determination for the UE in its specific radio environment. This can, in turn, improve demodulation results and overall communication performance and user experience at the UE. For example, using the different node to configure the search space size can allow for higher spectral efficiency where a base station (e.g., gNB) performs the calculations and adjusts the demodulator search space size according to the UE reports, as well as power saving at the UE, as the demodulator search space size calculations are done in the base station (e.g., gNB side), and there is no additional calculations in the UE side.

As used in this application, the terms "component," "module," "system" and the like are intended to include a computer-related entity, such as but not limited to hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components can communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets, such as data from one component interacting with another component in a local system, distributed system, and/or across a network such as the Internet with other systems by way of the signal.

Techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms "system" and "network" may often be used interchangeably. IS-<NUM> Releases <NUM> and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-<NUM> (TIA-<NUM>) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDM™, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies, including cellular (e.g., LTE) communications over a shared radio frequency spectrum band. The description below, however, describes an LTE/LTE-A system for purposes of example, and LTE terminology is used in much of the description below, although the techniques are applicable beyond LTE/LTE-A applications (e.g., to fifth generation (<NUM>) new radio (NR) networks or other next generation communication systems).

The wireless communications system (also referred to as a wireless wide area network (WWAN)) can include base stations <NUM>, UEs <NUM>, an Evolved Packet Core (EPC) <NUM>, and/or a <NUM> Core (5GC) <NUM>. The macro cells can include base stations. The small cells can include femtocells, picocells, and microcells. In an example, the base stations <NUM> may also include gNBs <NUM>, as described further herein. In one example, some nodes of the wireless communication system may have a modem <NUM> and UE communicating component <NUM> for receiving an indication related to a search space size to use for a demodulator, in accordance with aspects described herein. In addition, some nodes may have a modem <NUM> and BS communicating component <NUM> for configuring a search space size to use for a demodulator, in accordance with aspects described herein. Though a UE <NUM> is shown as having the modem <NUM> and UE communicating component <NUM> and a base station <NUM>/gNB <NUM> is shown as having the modem <NUM> and BS communicating component <NUM>, this is one illustrative example, and substantially any node or type of node may include a modem <NUM> and UE communicating component <NUM> and/or a modem <NUM> and BS communicating component <NUM> for providing corresponding functionalities described herein.

The base stations <NUM> configured for <NUM> LTE (which can collectively be referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC <NUM> through backhaul links <NUM> (e.g., using an S1 interface). The base stations <NUM> configured for <NUM> NR (which can collectively be referred to as Next Generation RAN (NG-RAN)) may interface with 5GC <NUM> through backhaul links <NUM>. The base stations <NUM> may communicate directly or indirectly (e.g., through the EPC <NUM> or 5GC <NUM>) with each other over backhaul links <NUM> (e.g., using an X2 interface).

The base stations <NUM> may wirelessly communicate with one or more UEs <NUM>. A network that includes both small cell and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group, which can be referred to as a closed subscriber group (CSG). The base stations <NUM> / UEs <NUM> may use spectrum up to Y MHz (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (e.g., for x component carriers) used for transmission in the DL and/or the UL direction. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

In another example, certain UEs <NUM> may communicate with each other using device-to-device (D2D) communication link <NUM>.

A base station <NUM>, whether a small cell <NUM>' or a large cell (e.g., macro base station), may include an eNB, gNodeB (gNB), or other type of base station. A base station <NUM> referred to herein can include a gNB <NUM>.

The 5GC <NUM> may include a Access and Mobility Management Function (AMF) <NUM>, other AMFs <NUM>, a Session Management Function (SMF) <NUM>, and a User Plane Function (UPF) <NUM>. The AMF <NUM> can be a control node that processes the signaling between the UEs <NUM> and the 5GC <NUM>. Generally, the AMF <NUM> can provide QoS flow and session management. User Internet protocol (IP) packets (e.g., from one or more UEs <NUM>) can be transferred through the UPF <NUM>. The UPF <NUM> can provide UE IP address allocation for one or more UEs, as well as other functions.

The base station <NUM> provides an access point to the EPC <NUM> or 5GC <NUM> for a UE <NUM>. IoT UEs may include machine type communication (MTC)/enhanced MTC (eMTC, also referred to as category (CAT)-M, Cat M1) UEs, NB-IoT (also referred to as CAT NB <NUM>) UEs, as well as other types of UEs. In the present disclosure, eMTC and NB-IoT may refer to future technologies that may evolve from or may be based on these technologies. For example, eMTC may include FeMTC (further eMTC), eFeMTC (enhanced further eMTC), mMTC (massive MTC), etc., and NB-IoT may include eNB-IoT (enhanced NB-IoT), FeNB-IoT (further enhanced NB-IoT), etc. The UE <NUM> may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

In an example, UE communicating component <NUM> can transmit information to a base station <NUM> to allow the base station <NUM> to determine a search space size for a demodulator of the UE <NUM>. For example, UE communicating component <NUM> can transmit a SRS, CSI feedback, or other signaling. BS communicating component <NUM> can receive the signaling and accordingly determine a search space size for the UE <NUM> to use in demodulating signals received from the base station <NUM> or other node of the wireless network. In this example, BS communicating component <NUM> can transmit an indication of the search space size to the UE <NUM>, and UE communicating component <NUM> can receive the indication of the search space size, determine the search space size for its demodulator, and accordingly generate LLRs for received signals based on the search space size.

Turning now to <FIG>, aspects are depicted with reference to one or more components and one or more methods that may perform the actions or operations described herein, where aspects in dashed line may be optional. Although the operations described below in <FIG> and <FIG> are presented in a particular order and/or as being performed by an example component, it should be understood that the ordering of the actions and the components performing the actions may be varied, depending on the implementation. Moreover, it should be understood that the following actions, functions, and/or described components may be performed by a specially programmed processor, a processor executing specially programmed software or computer-readable media, or by any other combination of a hardware component and/or a software component capable of performing the described actions or functions.

Referring to <FIG>, one example of an implementation of UE <NUM> may include a variety of components, some of which have already been described above and are described further herein, including components such as one or more processors <NUM> and memory <NUM> and transceiver <NUM> in communication via one or more buses <NUM>, which may operate in conjunction with modem <NUM> and/or UE communicating component <NUM> for receiving an indication related to a search space size to use for a demodulator, in accordance with aspects described herein.

In an aspect, the one or more processors <NUM> can include a modem <NUM> and/or can be part of the modem <NUM> that uses one or more modem processors. Thus, the various functions related to UE communicating component <NUM> may be included in modem <NUM> and/or processors <NUM> and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors <NUM> may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with transceiver <NUM>. In other aspects, some of the features of the one or more processors <NUM> and/or modem <NUM> associated with UE communicating component <NUM> may be performed by transceiver <NUM>.

Also, memory <NUM> may be configured to store data used herein and/or local versions of applications <NUM> or UE communicating component <NUM> and/or one or more of its subcomponents being executed by at least one processor <NUM>. Memory <NUM> can include any type of computer-readable medium usable by a computer or at least one processor <NUM>, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory <NUM> may be a non-transitory computer-readable storage medium that stores one or more computer-executable codes defining UE communicating component <NUM> and/or one or more of its subcomponents, and/or data associated therewith, when UE <NUM> is operating at least one processor <NUM> to execute UE communicating component <NUM> and/or one or more of its subcomponents.

Receiver <NUM> may include hardware, firmware, and/or software code executable by a processor for receiving data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). Additionally, receiver <NUM> may process such received signals, and also may obtain measurements of the signals, such as, but not limited to, Ec/Io, signal-to-noise ratio (SNR), reference signal received power (RSRP), received signal strength indicator (RSSI), etc. Transmitter <NUM> may include hardware, firmware, and/or software code executable by a processor for transmitting data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium).

In an aspect, UE communicating component <NUM> can optionally include a search space size component <NUM> for receiving an indication of a search space size, and/or a demodulating component <NUM> for demodulating one or more signals or generating LLRs based on the search space size, in accordance with aspects described herein.

Referring to <FIG>, one example of an implementation of base station <NUM> (e.g., a base station <NUM> and/or gNB <NUM>, as described above) may include a variety of components, some of which have already been described above, but including components such as one or more processors <NUM> and memory <NUM> and transceiver <NUM> in communication via one or more buses <NUM>, which may operate in conjunction with modem <NUM> and BS communicating component <NUM> for configuring a search space size to use for a demodulator, in accordance with aspects described herein.

In an aspect, BS communicating component <NUM> can optionally include a signal analyzing component <NUM> for analyzing a signal received from a UE for determining a search space size, a search space size determining component <NUM> for determining a search space size for the UE to use in demodulating signals, and/or a search space size indicating component <NUM> for transmitting an indication of the search space size to the UE, in accordance with aspects described herein.

<FIG> illustrates a flow chart of an example of a method <NUM> for determining or receiving a search space size to use for a demodulator, in accordance with aspects described herein. In an example, a UE <NUM> can perform the functions described in method <NUM> using one or more of the components described in <FIG>.

In method <NUM>, at Block <NUM>, an indication of a search space size for a demodulator to use in generating LLRs can be received. In an aspect, search space size component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM>, UE communicating component <NUM>, etc., can receive the indication of the search space size for the demodulator to use in generating LLRs. For example, a different node, such as a base station <NUM>, can determine the search space size for the UE <NUM> to use in demodulating signals received in wireless communication, and thus UE communicating component <NUM> can receive the indication of the search space size from the different node, such as base station <NUM>. In an example, the indication of the search space size can include a numeric representation of the search space size, a parameter on which the UE <NUM> can compute or otherwise determine the search space size, etc..

In an example, the different node can determine the search space size using a processor-intensive algorithm that may be too complex or use too much power or processing resources if performed by the UE <NUM>. In addition, for example, the different node may determine the search space size based on other considerations or experiences of other UEs known or reported to the different node. This can allow for more accurate search space size determination for the specific UE <NUM>. In an example, search space size component <NUM> can receive the indication of the search space size in downlink control information (DCI) from the base station <NUM> or in other dedicated control signaling for the UE <NUM>.

In method <NUM>, optionally at Block <NUM>, one or more signals for determining the search space size can be transmitted. In an aspect, search space size component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM>, UE communicating component <NUM>, etc., can transmit the one or more signals (e.g., uplink signals transmitted by the UE <NUM>) for determining the search space size. For example, the one or more signals may include a SRS, CSI feedback, or other signals that can indicate a channel quality value, such as a measurement of radio environment (e.g., a measurement of channel or signal quality or power of a channel or signal from a base station <NUM> or other node). For example, a measurement of channel or signal quality or power, which may be referred to herein as a channel quality value, may include a received signal strength indicator (RSSI), reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-noise ratio (SNR), signal-to-interference-and-noise ratio (SINR), etc. In any case, search space size component <NUM> may receive the indication of search space size based on transmitting the one or more signals.

In method <NUM>, optionally at Block <NUM>, the search space size can be determined based on the indication. In an aspect, search space size component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM>, UE communicating component <NUM>, etc., can determine, based on the indication, the search space size. For example, search space size component <NUM> can compute the search space size based on the indication where the indication includes one or more parameters for computing the search space size. For example, where the demodulator of the UE <NUM> uses <NUM>Mquadrature amplitude modulation (QAM), the indication of the search space size can include a reduction parameter i, which can be determined based on the one or more signals transmitted by the UE <NUM> at Block <NUM>. In this example, search space size component <NUM> can receive the indication as the reduction parameter i at Block <NUM>, and can determine the search space size as, or based on, <NUM>M-i.

In method <NUM>, optionally at Block <NUM>, one or more signals can be received in wireless communication. In an aspect, UE communicating component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM>, etc., can receive the one or more signals in wireless communication. For example, UE communicating component <NUM> can receive the one or more signals from the base station <NUM> (e.g., as downlink signals over designated downlink resources) or from one or more other base stations or UEs or other nodes in the wireless network.

In method <NUM>, at Block <NUM>, a demodulation of the one or more signals received in wireless communication can be performed using the demodulator and the search space size. In an aspect, demodulating component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM>, UE communicating component <NUM>, etc., can perform, using the demodulator and the search space size, the demodulation of the one or more signals received in wireless communication. For example, as described, the demodulator can be a PSRD demodulator or other type of demodulator that determines or generates LLRs based on a search space. In this example, demodulating component <NUM> can use the determined search space size in using a search space over a constellation for generating the LLRs via the demodulator.

<FIG> illustrates an example of a PSRD demodulator <NUM> that generates LLRs based on a search space for demodulating received signals in accordance with aspects of the present disclosure. In some examples, PSRD demodulator <NUM> may include, or be communicatively coupled with, a receive component <NUM>, channel estimator <NUM>, LLR component <NUM>, and decoder <NUM>. In addition, for example, demodulating component <NUM> can include, or can be communicatively coupled with or can communicate with, at least a portion of PSRD demodulator <NUM> to demodulate received signals based on a received or determined search space size.

As described with reference to <FIG>, PSRD demodulator <NUM> can be used to demodulate one or more transmissions received (e.g., from a base station <NUM>) at receive component <NUM>. Receive component <NUM> can be, or can be communicatively coupled with, a receiver of the UE <NUM> (e.g., such as a receiver <NUM> portion of transceiver <NUM>). In an example, channel estimator <NUM>, LLR component <NUM>, decoder <NUM>, etc. can also be part of, or communicatively coupled with, the receiver <NUM>, an associated receiver processor (e.g., Rx processor <NUM>) or other processor, RF front end <NUM>, modem <NUM>, and/or the like. In some cases, the transmissions may correspond to one or more symbols (e.g., one or more modulated signals) from one or more layers (e.g., MIMO), received on the same resource element (RE). Receive component <NUM> may produce a vector <MAT>, where vector <MAT> can be defined according to: <MAT> where His a matrix representation of the channel over which the transmission is received, <MAT> is the vector of precoded symbols from multiple layers at a RE of the transmission, and <MAT> is the vector of thermal noise at the RE of the transmission. Channel estimator <NUM> may determine matrix H, where matrix H is the matrix representation of the received channel over which the transmissions are received, of a dimension of receive (Rx) antennas by layer, and can be QR decomposed into H = QR, where R can be an upper diagonal matrix. In addition, vector <MAT> may correspond to a set of constellation symbols in a constellation <NUM>, where each constellation symbol may have a defined amplitude and phase of a set of amplitudes and phrases within a modulation scheme (e.g., quadrature phase shift keying (QPSK), <NUM>-QAM, <NUM>-QAM, etc.) used for modulating symbols of the transmission. Further, each constellation symbol may correspond to a unique bit sequence that may be represented by a received symbol.

For example, a base station <NUM> may transmit transmissions according to a <NUM> QAM modulation and coding scheme (MCS) such to include sixteen constellation symbols in constellation <NUM>. In such a case, each constellation symbol may correspond to one of the sixteen unique bit sequences that may be represented by a transmitted symbol. Where a base station <NUM> transmits transmissions according to a <NUM> QAM MCS, the transmission may include sixty-four constellation symbols such that each constellation symbol may correspond to one of the sixty-four unique bit sequences that may be represented by a transmitted symbol.

The generation of the LLR for some layer of interest (e.g., the last layer) may be based on a search over some search space around the received symbol of the layer of interest. The generation of the LLR for the layer of interest can include calculating a metric for each element of the search space. The metric may be composed from the hypothesis from the search space and some decisions over the interfering layers that are influenced from the current assumed hypothesis of the layer of interest. The size of the search space may therefore have an important factor on the demodulator complexity. At most the search space size can be over the entire constellation symbols (e.g., size K for a K-QAM constellation).

LLR component <NUM> may generate the LLRs based on QR decomposition, for a bit j, according to the following formula: <MAT> where <MAT> represents the vector of estimated symbols for the received signal vector <MAT>. LLR component <NUM> can provide the LLRs to decoder <NUM>, which may utilize the LLRs to determine a received bit sequence of the symbol and may perform an error detection procedure (e.g., a cyclic redundancy check (CRC)) on the received bit sequence. Upon determining that the determined LLR passes the error detection procedure, decoder <NUM> may generate acknowledgement (ACK) feedback to transmit to the base station <NUM>. Upon determining that the determined LLR fails the error detection procedure, decoder <NUM> may generate negative-acknowledgement (NACK) feedback to transmit to the base station <NUM>.

In accordance with aspects described herein, however, search space determining component <NUM> may determine the search space size of constellation <NUM> for LLR component <NUM> to use in generating LLRs. In an example, search space determining component <NUM> can receive an indication of search space size a reduction parameter i, where i = <NUM>. In this example, search space determining component <NUM> can determine to reduce the search space size to <NUM>M-i = <NUM><NUM>-<NUM> = <NUM>, as shown by reduced search space <NUM>. More generally the search space can be defined by any positive integer J (e.g., J <= K, for a K-QAM modulation). In this example, LLR component <NUM> can determine LLRs based on the reduced search space <NUM>, which may lower complexity and/or processing power required to generate the LLRs, and may allow for decoding based on the reduced search space <NUM> where channel conditions achieve a threshold (e.g., where the SRS, CSI, etc., exhibit desirable properties or measurements as described further herein.

In method <NUM>, optionally at Block <NUM>, the one or more demodulated signals can be processed in wireless communication. In an aspect, UE communicating component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM>, etc., can process the one or more demodulated signals in wireless communication. For example, UE communicating component <NUM> can pass a representative bit or bitstream to an upper layer for processing, transmit feedback for the received signals (e.g., ACK/NACK, as described above), and/or the like.

<FIG> illustrates a flow chart of an example of a method <NUM> for configuring a search space size to use for a demodulator, in accordance with aspects described herein. In an example, a base station <NUM> or other device can perform the functions described in method <NUM> using one or more of the components described in <FIG>.

In method <NUM>, at Block <NUM>, one or more signals for determining a search space size can be received. In an aspect, signal analyzing component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM>, BS communicating component <NUM>, etc., can receive the one or more signals for determining the search space size. For example, signal analyzing component <NUM> can receive the one or more signals from the UE <NUM>, such as a SRS, CSI feedback, or other signals from, or based on, which a radio environment at the UE <NUM> can be determined. For example, signal analyzing component <NUM> can determine the one or more signals as a latest received SRS, and can measure one or more properties of the SRS (e.g., RSSI, RSRP, RSRQ, SNR, SINR, etc.) for determining the search space size for a demodulator of the UE <NUM>. In another example, signal analyzing component <NUM> can determine, from the one or more signals, a delay from the latest received SRS for determining the search space size for a demodulator of the UE <NUM>. In yet another example, signal analyzing component <NUM> can determine channel quality indicated in CSI feedback for determining the search space size for a demodulator of the UE <NUM>.

In method <NUM>, at Block <NUM>, the search space size for a demodulator to use in generating LLRs can be determined based on the one or more signals. In an aspect, search space size determining component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM>, BS communicating component <NUM>, etc., can determine, based on the one or more signals, the search space size for the demodulator (e.g., of a UE <NUM>) to use in generating LLRs. For example, search space size determining component <NUM> can determine the search space size for the UE <NUM> to use in demodulating signals received from the base station <NUM> or from other nodes of the wireless network. For example, search space size determining component <NUM> can determine the search space size for the UE <NUM> based on properties of the one or more signals received at Block <NUM>, such that the search space size is determined for the UE <NUM> in its specific radio environment. As described, performing the search space size determination at the base station <NUM> may allow for more complex or intuitive determination logic to be performed.

In one specific example, search space size determining component <NUM> can determine the search space size for the UE <NUM> by inputting the signal metrics or properties received or determined from the one or more signals (e.g., a channel quality value) into a neural network or other AI process. The output of the neural network or AI process may be a reduction parameter, i, (or J for the more general case described above) for determining the search space (e.g., for a specific QAM or otherwise). For example, the more desirable the radio environment (e.g., the better the CSI feedback, the higher the measurement of SRS, etc.), search space size determining component <NUM> can determine a higher reduction parameter. In an example, the neural network can be used to model previous determined input (e.g., SRS properties or delay, CSI feedback, etc.) and how associated reduction parameters resulted in successful (e.g., ACK) or unsuccessful (NACK) in demodulation. In one example, the neural network can be modeled at a specific base station <NUM> to model the parameters of UEs <NUM> that have communicated with that base station <NUM> over a period of time. In another example, the neural network can be modeled based on simulated results or results of multiple base stations, and provided to the base station <NUM> for determining search space size (e.g., as a reduction parameter or otherwise).

In method <NUM>, at Block <NUM>, an indication of the search space size can be transmitted. In an aspect, search space size indicating component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM>, BS communicating component <NUM>, etc., can transmit the indication of the search space size. As described, for example, search space size indicating component <NUM> can transmit the indication of the search space size to a UE <NUM> in DCI or other signaling to allow the UE <NUM> to determine the search space size for demodulating signals received from the base station <NUM>, or other network nodes.

<FIG> is a block diagram of a MIMO communication system <NUM> including a base station <NUM> and a UE <NUM>. The MIMO communication system <NUM> may illustrate aspects of the wireless communication access network <NUM> described with reference to <FIG>. The base station <NUM> may be an example of aspects of the base station <NUM> described with reference to <FIG>. The base station <NUM> may be equipped with antennas <NUM> and <NUM>, and the UE <NUM> may be equipped with antennas <NUM> and <NUM>. In the MIMO communication system <NUM>, the base station <NUM> may be able to send data over multiple communication links at the same time. Each communication link may be called a "layer" and the "rank" of the communication link may indicate the number of layers used for communication. For example, in a 2x2 MIMO communication system where base station <NUM> transmits two "layers," the rank of the communication link between the base station <NUM> and the UE <NUM> is two.

The UE <NUM> may be an example of aspects of the UEs <NUM> described with reference to <FIG>. At the UE <NUM>, the UE antennas <NUM> and <NUM> may receive the DL signals from the base station <NUM> and may provide the received signals to the modulator/demodulators <NUM> and <NUM>, respectively. Each modulator/demodulator <NUM> through <NUM> may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each modulator/demodulator <NUM> through <NUM> may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector <NUM> may obtain received symbols from the modulator/demodulators <NUM> and <NUM>, perform MIMO detection on the received symbols, if applicable, and provide detected symbols. A receive (Rx) processor <NUM> may process (e.g., demodulate, deinterleave, and decode) the detected symbols, providing decoded data for the UE <NUM> to a data output, and provide decoded control information to a processor <NUM>, or memory <NUM>.

The processor <NUM> may in some cases execute stored instructions to instantiate a UE communicating component <NUM> (see e.g., <FIG> and <FIG>).

The processor <NUM> may in some cases execute stored instructions to instantiate a BS communicating component <NUM> (see e.g., <FIG> and <FIG>).

Similarly, the components of the base station <NUM> may, individually or collectively, be implemented with one or more application specific integrated circuits (ASICs) adapted to perform some or all of the applicable functions in hardware.

The above detailed description set forth above in connection with the appended drawings describes examples.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a specially programmed device, such as but not limited to a processor, a digital signal processor (DSP), an ASIC, a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic, a discrete hardware component, or any combination thereof designed to perform the functions described herein. A specially programmed processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A specially programmed processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Claim 1:
An apparatus (<NUM>) for wireless communication, comprising:
a transceiver (<NUM>);
a memory (<NUM>) configured to store instructions;
a per-stream recursive demapping, PSRD, demodulator communicatively coupled with the memory and the transceiver that demodulates signals received via the transceiver at least in part by generating log likelihood ratios, LLRs, by searching over a constellation corresponding to a search space; and
one or more processors (<NUM>) communicatively coupled with the demodulator, the memory, and the transceiver, wherein the one or more processors are configured to:
receive, from a base station, an indication of a search space size for the PSRD demodulator to use in generating the LLRs;
receive, from the base station, one or more signals within the search space; and
perform, using the PSRD demodulator, a demodulation of the one or more signals based on generating the LLRs by searching, based on the search space size, over the constellation corresponding to the search space.