Switching period symbol location for receiver switching

A method of wireless communication by a user equipment (UE) includes receiving, from a base station, a receive chain switching configuration for a multi-carrier environment. The UE also receives a physical downlink control channel (PDCCH) on one or more carriers of the multi-carrier environment with multiple receive chains, in accordance with the receive chain switching configuration. The UE decodes downlink control information (DCI) from the PDCCH for physical downlink shared channel (PDSCH) scheduling across multiple carriers in the multi-carrier environment. The UE performs receive chain switching based on the PDSCH scheduling from the decoded DCI and the receive chain switching configuration.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communications, and more particularly to techniques and apparatuses for 5G new radio (NR) switching period symbol location for receiver (Rx) switching.

BACKGROUND

A wireless communications network may include a number of base stations (BSs) that can support communications for a number of user equipment (UEs). A user equipment (UE) may communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communications link from the BS to the UE, and the uplink (or reverse link) refers to the communications link from the UE to the BS. As will be described in more detail, a BS may be referred to as a Node B, a gNB, an access point (AP), a radio head, a transmit and receive point (TRP), a new radio (NR) BS, a 5G Node B, and/or the like.

A UE may support high rank transmission (e.g., a larger number of receive chains) at higher bands because additional resources are available. A UE may support low or high rank transmissions (e.g., fewer or larger number of receive chains, such as one or two receive chains) at low-band because, for example, there are fewer resources available and low-band is beneficial for cell-edge UEs. Additionally, for UEs with reduced capability (which may be referred to as “RedCap UEs”), there may be only two receive chains and three or four antennas. For instance, the reduced capacity UE may be configured with one or two receive chains and may be switched between high-band and low-band. Unfortunately, because reduced capability UEs may have fewer or less complex resources, the UE may not simultaneously support two receive chain (2Rx) reception on high-band and one receive chain (1Rx) or 2Rx reception on low-band.

SUMMARY

In an aspect of the present disclosure, a method of wireless communication by a user equipment (UE) is provided. The method includes receiving, from a base station, a receive chain switching configuration for a multi-carrier environment. The method also includes receiving a physical downlink control channel (PDCCH) on one or more carriers of the multi-carrier environment with multiple receive chains, in accordance with the receive chain switching configuration. Additionally, the method includes decoding, from the PDCCH, downlink control information (DCI) for physical downlink shared channel (PDSCH) scheduling across multiple carriers in the multi-carrier environment. Further, the method includes performing receive chain switching based on the PDSCH scheduling from the decoded DCI and the receive chain switching configuration.

In another aspect of the present disclosure, an apparatus for wireless communication by a user equipment (UE) is provided. The apparatus includes a memory and one or more processors coupled to the memory. The processor(s) are configured to receive, from a base station, a receive chain switching configuration for a multi-carrier environment. The processor(s) are also configured to receive a physical downlink control channel (PDCCH) on one or more carriers of the multi-carrier environment with multiple receive chains, in accordance with the receive chain switching configuration. In addition, the processor(s) are configured to decode, from the PDCCH, downlink control information (DCI) for physical downlink shared channel (PDSCH) scheduling across multiple carriers in the multi-carrier environment. Further, the processor(s) are configured to perform receive chain switching based on the PDSCH scheduling from the decoded DCI and the receive chain switching configuration.

In yet another aspect of the present disclosure, an apparatus for wireless communication by a user equipment (UE) is provided. The apparatus includes means for receiving, from a base station, a receive chain switching configuration for a multi-carrier environment. The apparatus also includes means for receiving a physical downlink control channel (PDCCH) on one or more carriers of the multi-carrier environment with multiple receive chains, in accordance with the receive chain switching configuration. The apparatus additionally includes means for decoding, from the PDCCH, downlink control information (DCI) for physical downlink shared channel (PDSCH) scheduling across multiple carriers in the multi-carrier environment. Furthermore, the apparatus includes means for performing receive chain switching based on the PDSCH scheduling from the decoded DCI and the receive chain switching configuration.

In a further aspect of the present disclosure, a non-transitory computer readable medium is provided. The computer readable medium has encoded thereon program code for wireless communication by a user equipment (UE). The program code is executed by the UE and includes code to receive, from a base station, a receive chain switching configuration for a multi-carrier environment. The program code also includes code to receive a physical downlink control channel (PDCCH) on one or more carriers of the multi-carrier environment with multiple receive chains, in accordance with the receive chain switching configuration. The program code additionally includes code to decode, from the PDCCH, downlink control information (DCI) for physical downlink shared channel (PDSCH) scheduling across multiple carriers in the multi-carrier environment. Furthermore, the program code includes code to perform receive chain switching based on the PDSCH scheduling from the decoded DCI and the receive chain switching configuration.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communications device, and processing system as substantially described with reference to and as illustrated by the accompanying drawings and specification.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully below with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings, one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth. It should be understood that any aspect of the disclosure disclosed may be embodied by one or more elements of a claim.

It should be noted that while aspects may be described using terminology commonly associated with 5G and later wireless technologies, aspects of the present disclosure can be applied in other generation-based communications systems, such as and including 3G and/or 4G technologies.

A UE may be configured to support high rank transmission (e.g., a larger number of receive chains) at higher bands because additional resources are available. A UE may support low or high rank transmissions (e.g., fewer or larger number of receive chains, such as one or two receive chains) at low-band because, for example, there are fewer resources available and low-band is beneficial for cell-edge UEs. Additionally, some UEs may have reduced capability. These reduced capacity UEs (which may be referred to as “RedCap UEs”) may be characterized by lower complexity and reduced energy consumption compared to other UEs. The reduced capacity UEs may include NR-Light UEs and Internet of Things (IoT) devices. In one example, a UE with reduced capability may be configured with only two receive chains and three or four antennas. For instance, the reduced capacity UE may be configured with one or two receive chains and may be switched between high-band and low-band. Unfortunately, because reduced capability UEs may have fewer or less complex resources, the UE may not simultaneously support two receive chain (2Rx) reception on high-band and one receive chain (1Rx) or 2Rx reception on low-band.

Aspects of the present disclosure are directed to a switching period location for scheduling reception of a physical downlink shared channel (PDSCH) across multiple component carriers in a carrier aggregation environment. In some aspects, the switching period or location may be configured for receiving a physical downlink control channel (PDCCH) on multiple carriers simultaneously for decoding downlink control information (DCI) for PDSCH scheduling across multiple carriers. The DCI provides a UE with information, such as physical layer resource allocation, power control commands, and other control information.

As an example, the BSs110(shown as BS110a, BS110b, BS110c, and BS110d) and the core network130may exchange communications via backhaul links132(e.g., S1, etc.). Base stations110may communicate with one another over other backhaul links (e.g., X2, etc.) either directly or indirectly (e.g., through core network130).

The core network130may provide user authentication, access authorization, tracking, IP connectivity, and other access, routing, or mobility functions. One or more of the base stations110or access node controllers (ANCs) may interface with the core network130through backhaul links132(e.g., S1, S2, etc.) and may perform radio configuration and scheduling for communications with the UEs120. In some configurations, various functions of each access network entity or base station110may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., a base station110).

One or more UEs120may establish a protocol data unit (PDU) session for a network slice. In some cases, the UE120may select a network slice based on an application or subscription service. By having different network slices serving different applications or subscriptions, the UE120may improve its resource utilization in the wireless communications system100, while also satisfying performance specifications of individual applications of the UE120. In some cases, the network slices used by UE120may be served by an AMF (not shown inFIG.1) associated with one or both of the base station110or core network130. In addition, session management of the network slices may be performed by an access and mobility management function (AMF).

The UEs120may include a receive (Rx) switching module140. For brevity, only one UE120dis shown as including the Rx switching module140. The Rx switching module140may receive, from a base station, a receive chain switching configuration for a multi-carrier environment. The Rx switching module14may also receive a physical downlink control channel (PDCCH) on at least one carrier of the multi-carrier environment with multiple receive chains, in accordance with the receive chain switching configuration. Additionally, the Rx switching module140may decode, from the PDCCH, downlink control information (DCI) for physical downlink shared channel (PDSCH) scheduling across multiple carriers in the multi-carrier environment. Furthermore, the Rx switching module140may perform receive chain switching based at least in part on the PDSCH scheduling from the decoded DCI and the receive chain switching configuration.

In some aspects, two or more UEs120(e.g., shown as UE120aand UE120e) may communicate directly using one or more sidelink channels (e.g., without using a base station110as an intermediary to communicate with one another). For example, the UEs120may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (e.g., which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, and/or the like), a mesh network, and/or the like. In this case, the UE120may perform scheduling operations, resource selection operations, and/or other operations described elsewhere as being performed by the base station110. For example, the base station110may configure a UE120via downlink control information (DCI), radio resource control (RRC) signaling, a media access control-control element (MAC-CE) or via system information (e.g., a system information block (SIB).

As indicated above,FIG.1is provided merely as an example. Other examples may differ from what is described with regard toFIG.1.

FIG.2shows a block diagram of a design200of the base station110and UE120, which may be one of the base stations and one of the UEs inFIG.1. The base station110may be equipped with T antennas234athrough234t, and UE120may be equipped with R antennas252athrough252r, where in general T≥1 and R≥1.

At the UE120, antennas252athrough252rmay receive the downlink signals from the base station110and/or other base stations and may provide received signals to demodulators (DEMODs)254athrough254r, respectively. Each demodulator254may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator254may further process the input samples (e.g., for OFDM and/or the like) to obtain received symbols. A MIMO detector256may obtain received symbols from all R demodulators254athrough254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor258may process (e.g., demodulate and decode) the detected symbols, provide decoded data for the UE120to a data sink260, and provide decoded control information and system information to a controller/processor280. A channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), and/or the like. In some aspects, one or more components of the UE120may be included in a housing.

On the uplink, at the UE120, a transmit processor264may receive and process data from a data source262and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) from the controller/processor280. Transmit processor264may also generate reference symbols for one or more reference signals. The symbols from the transmit processor264may be precoded by a TX MIMO processor266if applicable, further processed by modulators254athrough254r(e.g., for DFT-s-OFDM, CP-OFDM, and/or the like), and transmitted to the base station110. At the base station110, the uplink signals from the UE120and other UEs may be received by the antennas234, processed by the demodulators254, detected by a MIMO detector236if applicable, and further processed by a receive processor238to obtain decoded data and control information sent by the UE120. The receive processor238may provide the decoded data to a data sink239and the decoded control information to a controller/processor240. The base station110may include communications unit244and communicate to the core network130via the communications unit244. The core network130may include a communications unit294, a controller/processor290, and a memory292.

The controller/processor of the UE120, and/or any other component(s) ofFIG.2may perform one or more techniques associated with a switching period symbol location for receiver (Rx) switching, as described in more detail elsewhere. For example, the controller/processor280of the UE120, and/or any other component(s) ofFIG.2may perform or direct operations of, for example, the process ofFIG.9and/or other processes as described. Memories242and282may store data and program codes for the base station110and UE120, respectively. A scheduler246may schedule UEs for data transmission on the downlink and/or uplink.

In some aspects, the UE120may include means for receiving, from a base station, a receive chain switching configuration for a multi-carrier environment. The UE120may also include means receiving a physical downlink control channel (PDCCH) on at least one carrier of the multi-carrier environment with multiple receive chains, in accordance with the receive chain switching configuration. The UE120may additionally include means for decoding, from the PDCCH, downlink control information (DCI) for physical downlink shared channel (PDSCH) scheduling across multiple carriers in the multi-carrier environment. Furthermore, the UE120may include means for performing receive chain switching based on the PDSCH scheduling from the decoded DCI and the receive chain switching configuration. Such means may include one or more components of the UE120described in connection withFIG.2.

As indicated above,FIG.2is provided merely as an example. Other examples may differ from what is described with regard toFIG.2.

A resource grid may represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

FIGS.4A and4Bare diagrams illustrating example receive chain configurations of a user equipment (UE), in accordance with aspects of the present disclosure. Referring toFIG.4A, a UE400includes two receive (Rx) chains (e.g., Rx chain 0 and Rx chain 1) and three antennas (e.g., high-band Ant 0, high-band Ant 1, and low-band Ant 1). Rx chain 0 uses high-band antenna Ant 0. On the other hand, Rx chain 1 may be switched between low-band or high-band communication on low-band Ant 1 or high-band Ant 1, respectively.

Referring toFIG.4B, a UE420includes two receive chains (e.g., Rx chain 0 and Rx chain 1) and four antennas (e.g., high-band Ant 1, high-band Ant 2, low-band Ant 1, and low-band Ant 2). In the UE420, each of the Rx chains may be switched between high-band or low-band communication. For instance, the Rx chain 0 may be switched between a high-band antenna (e.g., high-band Ant 1) and a low-band antenna e.g., (low-band Ant 1). Likewise, the Rx chain 1 may be switched between a high-band antenna (e.g., high-band Ant 2) and a low-band antenna (e.g., low-band Ant 2).

The transmission on high-band or low-band for the UE400and UE420may be semi-static (e.g., periodic) or dynamic based on scheduling via a base station (e.g., a gNB) across two carriers (e.g., supplementary downlink (SDL), carrier aggregation (CA), evolved-universal mobile telecommunications service (UMTS) terrestrial radio access network (E-UTRAN) new radio dual connectivity (EN-DC)). The carriers may both be time division duplex (TDD) carriers or may be one TDD carrier and one frequency division duplex (FDD) carrier, for example.

Accordingly, in an aspect of the present disclosure, a receive switching pattern and a carrier switching period configuration is disclosed. The receive switching pattern and carrier switching period may be configured by radio resource control (RRC) signaling or a medium access control-control element (MAC-CE) by the base station (e.g., gNB). In some aspects, the receive switching pattern may include two receive chains configured for receiving for physical downlink control channel (PDCCH) on one carrier for decoding downlink control information (DCI) for physical downlink shared channel (PDSCH) scheduling across two carriers.

FIG.4Cis a table450listing example configurations for time division multiplexed (TDM) downlink (DL) carrier aggregation (CA). Referring toFIG.4C, three example cases are shown for DL CA in the table450. For TDD+FDD CA (on a first component carrier (CC1)) in case 1, a IE may receive up to two layers at a TDD carrier. In case 2, the UE may receive one layer at an FDD carrier. For TDD+TDD (on a second component carrier (CC2)), there are three example cases shown. In case 1, the UE may receive up to a two-layer transmission on a first TDD carrier. In case 2, the UE may receive up to a two-layer transmission on a second TDD carrier. In case 3, the UE receives a one-layer transmission from the first TDD carrier and a one-layer transmission from the second TDD carrier. Accordingly, the UE only needs two receive chains and can switch receive chains across two bands to support TDM downlink carrier aggregation.

In accordance with aspects of the present disclosure, receive switching patterns or schemes may be defined. In some aspects, the receive switching pattern may include a cross-carrier scheduling pattern. In cross-carrier scheduling, two receive layers for PDCCH may be received on one carrier for decoding DCI for PDSCH scheduling across two carriers.

In some aspects, the receive switching pattern may include a self-carrier scheduling pattern. In the self-carrier scheduling pattern, two carriers each receive a PDCCH. In some aspects, the carriers may receive the PDCCH simultaneously. As such, one receive layer for PDCCH may be received on both carriers for decoding the DCI for PDSCH scheduling across two carriers.

FIG.5Ais an example diagram500illustrating cross-carrier scheduling, in accordance with aspects of the present disclosure. As shown inFIG.5A, a TDD carrier 1 receives a PDCCH with two receive antennas for scheduling a PDSCH across both the TDD carrier 1 and a TDD carrier 2. In time slots 0 and 1, the TDD carrier 1 receives the PDCCH (502) for scheduling the PDSCH on carrier 1 while the TDD carrier 2 receives no PDSCH. Because the scheduling is only on TDD carrier 1, no receive switching is performed in time slot 0 and time slot 1, so a switching period is not configured and two receive chains are placed on the TDD carrier 1. In time slot 2, the UE also receives PDCCH on the TDD carrier 1 but the PDCCH scheduling of PDSCH reception is on the TDD carrier 2. Thus, the UE switches the receive chain from TDD carrier 1 to TDD carrier 2. To allow sufficient time for the carrier switch, a switching gap or period504may be inserted such that the PDSCH is scheduled to be received on TDD carrier 2 following the switching period504. After receiving the PDSCH in time slot 2, the UE switches the receive chain from TDD carrier 2 to the TDD carrier 1 to receive the next PDCCH (in time slot 3). To allow sufficient time for the carrier switch (e.g., from the TDD carrier 2 to the TDD carrier 1) a switching gap or period504is also configured following the PDSCH reception in time slot 2.

In time slot 3, the UE receives the PDCCH on the TDD carrier 1 with the scheduling of the PDSCH receive on TDD carrier 2 in a special (S) slot. The UE switches the two receive chains from TDD carrier 1 to TDD carrier 2. A switching gap or period504may be inserted prior to the PDSCH reception to accommodate the switch. However, because the special (S) slot includes guard symbols at the conclusion of the downlink receive period during which a transmission is not received, the UE may switch the two receive chains to TDD carrier 1 without the inclusion of a switching period and the symbols for downlink transmission on TDD carrier 1 may be read (e.g., time slot 4).

In time slot 6, TDD carrier 1 again receives PDCCH. However, in time slot 6, the scheduling is for the UE to receive the PDSCH on both TDD carrier 1 and TDD carrier 2. That is, one layer may be received on each carrier. As such, the UE switches one receive chain from TDD carrier 1 to TDD carrier 2. To allow sufficient time for the carrier switch (TDD carrier 1 to TDD carrier 2), a switching gap or period504is also configured to precede the PDSCH reception on TDD carrier 2 in time slot 6. After receiving the PDSCH in time slot 6, the UE switches the receive chain from TDD carrier 2 to the TDD carrier 1 to receive the next PDCCH (time slot 7). Thus, another switching gap504is present. Similarly, a switching gap504is provided prior to switching in slot 7 for downlink reception during the special slot (S).

FIG.5Bis a diagram illustrating an example of self-carrier scheduling in accordance with aspects of the present disclosure. Referring toFIG.5B, in time slot 0, the UE receives PDCCH on both carriers (e.g., TDD carrier 1 and TDD carrier 2), simultaneously with one receive chain on TDD carrier 1 and one receive chain on TDD carrier 2. In time slot 0, the PDSCH is only scheduled on TDD carrier 1. The UE switches one receive chain from TDD carrier 2 to TDD carrier 1 to receive a two-layer PDSCH on TDD carrier 1. To accommodate the switching of the receive chain, a switching period554may be included prior to and following PDSCH reception. In time slot 1, the UE again receives the PDCCH on both carriers, however, the UE receives a one-layer PDSCH on TDD carrier 1 and a one-layer PDSCH on the TDD carrier 2. Because a receive switch is not performed for the PDSCH reception in slot 1, a switching gap or period is not configured.

In time slot 2, the UE receives the PDCCH on both carriers, for PDSCH scheduled on TDD carrier 2 only. The UE switches one receive chain from TDD carrier 1 to the TDD carrier 2 to receive a two-layer PDSCH on TDD carrier 2.

The location of the switching period symbols may be semi-statically configured by radio resource control (RRC) signaling on one specified carrier of the two downlink carriers. In cross-carrier scheduling, for downlink slots, a carrier switching period is not present for every downlink receive period, for instance, if the downlink slot on one carrier overlaps an uplink slot on the other carrier.

AlthoughFIGS.5A and5Brefer to TDD configurations, FDD configurations are also contemplated. In this case, all slots are treated as downlink slots. That is, only downlink carriers are considered.

FIGS.6A and6Bare diagrams600and650, respectively, illustrating cross-carrier scheduling examples, in accordance with aspects of the present disclosure. InFIG.6A, the frequency location of the switching periods is semi-statically configured by RRC signaling on TDD carrier 2. In time slot 4, a downlink slot of a TDD carrier 1 overlaps an uplink slot of the TDD carrier 2, so a carrier switch period is not configured.

On the other hand, if a switching period is present, the switching period is placed on the first one or more downlink symbols and the last one or more downlink symbols of a downlink receive period. For example, as shown inFIG.6A, in time slot 2, a UE operating with a cross-scheduling configuration receives a PDCCH on TDD carrier 1 scheduling two-layer PDSCH reception on TDD carrier 2. As such, the UE switches two receive chains to TDD carrier 2. To accommodate the receive switch, a switching period604is placed on the first one or more downlink symbols and the last one or more downlink symbols of the downlink receive period of time slot 2 of TDD carrier 2.

For special slots with the cross-scheduling, a switching period is only placed on the first one or more downlink symbols of the downlink receive period. For instance, referring again toFIG.6A, in time slot 3 for TDD carrier 2, a switching period604is placed only on the first one or more downlink symbols of the downlink receive period. The switch gap604is not included in the last one or more symbols because the special slot includes a gap period and uplink symbols at the end of the special slot, during which the receive chain can switch.

Referring toFIG.6B, the frequency location of the switching periods is semi-statically configured by RRC signaling on TDD carrier 1. For instance, in time slot 2, a UE operating using a cross-scheduling scheme, receives a PDCCH on the TDD carrier 1 for a two-layer PDSCH reception on a TDD carrier 2. As such, the UE switches two receive chains to TDD carrier 2. To accommodate the receive switch, a switching period654is placed on the first one or more downlink symbols and the last one or more downlink symbols of the downlink receive period of time slot 2 of TDD carrier 1.

FIGS.7A and7Bare diagrams700, and750, respectively, illustrating self-carrier scheduling examples, in accordance with aspects of the present disclosure. InFIG.7A, the frequency location of the switching periods is semi-statically configured by RRC signaling on TDD carrier 2, and inFIG.7B, the frequency location of the switching period is semi-statically configured by RRC signaling on TDD carrier 1. That is, the frequency location of the switching periods is semi-statically configured on one specific carrier of the two downlink carriers.

In self-scheduling for downlink slots, a carrier switching period is not present for every downlink receive period, for example, if a UE is scheduled to receive a rank 1 PDSCH on both carriers simultaneously. This is shown, for instance, inFIGS.7A and7Bat time slot 1. In time slot 1, a UE is scheduled to receive a one-layer PDSCH on TDD carrier 1 and TDD carrier 2, simultaneously. As such, a switching period is not configured for time slot 1 because one receive chain is already assigned to each TDD carrier.

If, however, the switching period is present, the switching period may be placed on the first one or more downlink symbols and the last one or more downlink symbols of a downlink receive period. For instance, referring toFIG.7A, in time slot 2, the UE receives a PDCCH (702) on TDD carrier 1 and TDD carrier 2 for a two-layer PDSCH reception on the TDD carrier 2. As such, the RRC configuration may include a switching period704on TDD carrier 2 for the first one or more downlink symbols and the last one or more downlink symbols of a downlink receive period of time slot 2.

In some implementations, the switching period704is placed on only the last one or more downlink symbols of a downlink receive period if the downlink on one carrier overlaps an uplink slot on the other carrier. For instance, referring toFIG.7A, in time slot 4, a downlink slot of TDD carrier 1 overlaps an UL slot of TDD carrier 2. Accordingly, with the switching periods configured for TDD carrier 2, the switching period704is placed only on the last one or more downlink symbols of the downlink receive period of TDD carrier 2. Similarly, referring toFIG.7B, in time slot 4, with the switching periods configured for TDD carrier 1, a switching period754is placed only on the last one or more downlink symbol of the downlink receive period of TDD carrier 1.

Additionally, in some implementations, for a special slot in the self-scheduling scheme, a switching period is only placed on the first one or more downlink symbols of a downlink receive period. For example, referring toFIG.7A, in time slot 3, the TDD carrier 2 has a special (S) slot in time slots 3 and 7. The switching period704is included only on the first one or more downlink symbols of the receive period.

The number of symbols included in the switching period to accommodate the receive switch from one carrier to the other is determined based on the UE capabilities. For instance, the switching period may be based on the number of antennas, UE bandwidth, or other measures of UE capabilities.

FIG.8is a diagram800illustrating a downlink receive period802, in accordance with aspect of the present disclosure. The downlink receive period802starts from a symbol, which is immediately subsequent to a control resource set (CORESET)/PDCCH symbol804, and extends to the last downlink symbol of a downlink slot or to a last guard symbol806of a special (S) slot (see time slot 3) on the configured carrier.

As indicated above,FIGS.4-8are provided as examples. Other examples may differ from what is described with respect toFIGS.4-8.

FIG.9is a diagram illustrating an example process900performed, for example, by a user equipment (UE), in accordance with various aspects of the present disclosure. The UE may, for instance, be a reduced capability UE such as an NR-light or an Internet of Things (IoT) device. In block902, the process900receives, from a base station, a receive (Rx) chain switching configuration for a multi-carrier environment. For example, Rx switching gaps may be configured as shown inFIGS.5A-8.

In block904, the process900receives a physical downlink control channel (PDCCH) on one or more carriers of the multi-carrier environment with multiple receive chains, in accordance with the receive chain switching configuration. For instance, as shown inFIG.5A, in time slots 0 and 1, the TDD carrier 1 receives the PDCCH (502) for scheduling a PDSCH on TDD carrier 1, in accordance with a cross scheduling Rx switching configuration. In some aspects, the process may receive the PDCCH on multiple carriers simultaneously, with one receive chain assigned to each carrier. For instance, as discussed with reference toFIG.5B, in time slot 0, the UE receives the PDCCH on both carriers (e.g., TDD carrier 1 and TDD carrier 2), simultaneously with one receive chain on TDD carrier 1 and one receive chain on TDD carrier 2.

In block906, the process decodes, from the PDCCH, downlink control information (DCI) for physical downlink shared channel (PDSCH) scheduling across multiple carriers in the multi-carrier environment. As shown inFIG.5A, TDD carrier 1 receives the PDCCH with two Rx antennas for scheduling the PDSCH across both TDD carrier 1 and TDD carrier 2. As shown inFIG.5Bat slot 0, TDD carrier 1 and TDD carrier 2 each receive the PDCCH with one Rx antenna for scheduling the PDSCH in TDD carrier 1.

In block908, the process performs receive chain switching based at least in part on the PDSCH scheduling from the decoded DCI and the Rx switching configuration. In some aspects, the receive chain switching may include switching one or more of the receive chains to a second carrier during a switching period if a downlink slot of the first carrier overlaps with a downlink slot of the second carrier. As shown for example inFIG.8, a switching period may include a first one or more symbols of a downlink reception period of a configured carrier and a last one or more symbols of the downlink reception period of the configured carrier.

Additionally, in some aspects, multiple receive chains may be maintained on current carriers when a downlink reception period of the first carrier overlaps with an uplink slot of a second carrier. For example, as shown inFIG.6Ain time slot 4, a downlink slot of TDD carrier 1 overlaps an uplink slot of the TDD carrier 2, so a carrier switch period is not configured.

As used, the term “component” is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software. As used, a processor is implemented in hardware, firmware, and/or a combination of hardware and software.