Enhancement for dynamic spectrum sharing

Abstract

A user equipment (UE) is configured to receive information associated with a downlink reference signal for a first radio access technology (RAT), wherein the first RAT is different from a second RAT currently serving; identifying a reference signal occasion for the downlink reference signal; and receiving downlink control information (DCI) from the second RAT via a physical downlink control channel (PDCCH), wherein one or more DCIs and one or more reference signal occasions occupy the same symbol.

Description

Technical Field

[0001] The present disclosure relates generally to communications, and more particularly, to enhancements to dynamic spectrum sharing. Background Art

[0002] Network operators can deploy fifth-generation (5G) New Radio (NR) services on top of spectrum already used for Long Term Evolution (LTE) services. When multiple radio access technologies (RATs) share the same frequency band, collisions can occur between signals from different RATs. In this type of deployment scenario, dynamic spectrum sharing (DSS) can be leveraged to ensure coexistence of 5G NR and LTE using the same spectrum. Technologies are needed to ensure that the 5G NR physical downlink control channel (PDCCH) can coexist with LTE downlink reference signals. Summary of the Invention

[0003] Some example embodiments relate to a processor of a user equipment (UE) configured to perform operations including: receiving information associated with a downlink reference signal for a first radio access technology (RAT), wherein the first RAT is different from a currently serving second RAT; identifying a reference signal opportunity for the downlink reference signal; and receiving downlink control information (DCI) from the second RAT via a physical downlink control channel (PDCCH), wherein one or more DCIs and one or more reference signals time-occupy the same symbol.

[0004] Other exemplary embodiments relate to a user equipment (UE) having: a transceiver configured to communicate with a network; and a processor communicatively coupled to the transceiver and configured to perform operations. The operations include: receiving information associated with a downlink reference signal for a first radio access technology (RAT), wherein the first RAT is different from a currently serving second RAT; identifying a reference signal opportunity for the downlink reference signal; and receiving downlink control information (DCI) from the second RAT via a physical downlink control channel (PDCCH), wherein one or more DCI and one or more reference signals time-occupy the same symbol.

[0005] Additional example embodiments relate to a processor of a base station configured to perform operations including identifying reference signal opportunities for a downlink reference signal of a first radio access technology (RAT) and transmitting downlink control information (DCI) to a user equipment (UE) via a physical downlink control channel (PDCCH) of a second RAT, wherein one or more DCI and one or more reference signal opportunities occupy the same symbol.

[0006] Additional exemplary embodiments relate to a base station having a transceiver configured to communicate with a user equipment (UE); and a processor communicatively coupled to the transceiver and configured to perform operations. The operations include identifying reference signal opportunities for downlink reference signals of a first radio access technology (RAT); and transmitting downlink control information (DCI) to the user equipment (UE) via a physical downlink control channel (PDCCH) of a second RAT, wherein one or more DCI and one or more reference signal opportunities occupy the same symbol. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 Exemplary network arrangements are shown according to various exemplary embodiments.

[0008] Figure 2 An exemplary user equipment (UE) is shown in accordance with various exemplary embodiments.

[0009] Figure 3 An exemplary base station is shown in accordance with various exemplary embodiments.

[0010] Figure 4 Methods for Physical Data Control Channel (PDCCH) reception according to various exemplary embodiments are shown.

[0011] Figure 5 An example of Abstract Syntax Notation One (ASN.1) for a SearchSpace Information Element (IE) is shown, according to various exemplary embodiments.

[0012] Figure 6 Examples of exemplary LTE cell-specific reference signal (CRS) designs are shown in accordance with various exemplary embodiments.

[0013] Figure 7 Examples of Physical Downlink Control Channel (PDCCH) Demodulation Reference Signal (DMRS) designs are shown according to various exemplary embodiments.

[0014] Figure 8 Examples of collision handling techniques for collisions between 5G NR PDCCH data and LTE CRS within a symbol are shown, according to various exemplary embodiments.

[0015] Figure 9 Examples of collision handling techniques for collisions between 5G NR PDCCH DMRS and LTE CRS within a symbol are shown according to various exemplary embodiments. DETAILED DESCRIPTION

[0016] The exemplary embodiments may be further understood with reference to the following description and associated drawings, wherein similar elements bear the same reference numerals. The exemplary embodiments relate to 5G New Radio (NR) Physical Downlink Control Channel (PDCCH) transmission and reception. As will be described in greater detail below, the exemplary embodiments introduce enhancements for dynamic spectrum sharing (DSS) between Long Term Evolution (LTE) radio access technologies (RATs) and 5G New Radio (NR) RATs.

[0017] The exemplary embodiments are described with respect to a UE. However, reference to a UE is provided for illustrative purposes only. The exemplary embodiments may be used with any electronic component that can establish a connection with a network and is configured with hardware, software, and / or firmware for exchanging information and data with the network. Therefore, UE as described herein is used to represent any electronic component.

[0018] Those skilled in the art will understand that DSS refers to the deployment of multiple RATs in the same frequency band and the dynamic allocation of spectrum resources between those RATs. DSS can enable network operators to deploy 5G NR on top of the spectrum already used for LTE. However, when multiple RATs share the same frequency band, conflicts may occur between signals from different RATs. This can result in performance degradation on the UE side and / or the network side for LTE operation and 5G NR operation. Although the exemplary embodiments are described with reference to 5G RATs and LTE RATs sharing spectrum, those skilled in the art will understand that the principles described herein can be implemented in any RAT that can share spectrum.

[0019] In accordance with various regulations and / or standards, DSS can be configured to ensure that LTE operation is not affected by the presence of 5G NR communications in the same frequency band. Since 5G NR communications are invisible to LTE operation, DSS can rely on 5G NR-based mechanisms. For example, 5G NR PDCCH reception may include rate matching around LTE cell-specific reference signals (CRS). These types of mechanisms ensure backward compatibility for legacy LTE UEs and allow RATs to coexist in the same spectrum.

[0020] According to some aspects, exemplary embodiments introduce techniques related to when and under what conditions rate matching around LTE CRS is performed for PDCCH reception. These constraints enable operators to meet DSS requirements without placing unreasonable demands on the UE or the network. In another aspect, exemplary embodiments introduce conflict resolution techniques for 5G NR PDCCH and LTE CRS. The exemplary techniques described herein can be used independently of each other, in combination with other currently implemented DSS mechanisms, in combination with future implementations of DSS mechanisms, or independently of other DSS mechanisms.

[0021] Figure 1 An exemplary network arrangement 100 according to various exemplary embodiments is shown. The exemplary network arrangement 100 includes a UE 110. Those skilled in the art will appreciate that the UE 110 can be any type of electronic component configured to communicate via a network, such as a mobile phone, tablet computer, desktop computer, smartphone, phablet, embedded device, wearable device, Internet of Things (IoT) device, etc. It should also be understood that an actual network arrangement can include any number of UEs used by any number of users. Therefore, for illustrative purposes, only an example with a single UE 110 is provided.

[0022] UE 110 can be configured to communicate with one or more networks. In the example of network configuration 100, the networks with which UE 110 can wirelessly communicate are 5G NR radio access network (RAN) 120, LTE RAN 122, and wireless local area network (WLAN) 124. However, it should be understood that UE 110 can also communicate with other types of networks (e.g., 5G cloud RAN, next generation RAN (NG-RAN), traditional cellular networks, etc.), and UE 110 can also communicate with the network through a wired connection. With respect to the exemplary embodiment, UE 110 can establish a connection with 5G NR RAN 120, LTE RAN 122, and / or WLAN 124. Thus, UE 110 can have a 5G NR chipset for communicating with NR RAN 120, an LTE chipset for communicating with LTE-RAN 122, and an ISM chipset for communicating with WLAN 124.

[0023] 5G NR RAN 120 and LTE RAN 122 may be part of a cellular network that may be deployed by a network operator (e.g., Verizon, AT&T, T-Mobile, etc.). RANs 120 and 122 may include cells or base stations configured to transmit and receive traffic from UEs equipped with appropriate cellular chipsets. In this example, 5G NR RAN 120 includes gNB 120A, and LTE RAN 122 includes eNB 122A. However, reference to gNB and eNB is provided for illustrative purposes only, and any suitable base station or cell (e.g., Node B, eNodeB, HeNB, eNB, gNB, gNodeB, macrocell, microcell, small cell, femtocell, etc.) may be deployed. WLAN 124 may include any type of wireless local area network (WiFi, hotspot, IEEE 802.11x network, etc.).

[0024] Those skilled in the art will appreciate that any relevant procedures may be performed for UE 110 to connect to 5G NR RAN 120. For example, as described above, 5G NR RAN 120 may be associated with a specific network operator, where UE 110 and / or its user has protocol and credential information (e.g., stored on a SIM card). Upon detecting the presence of 5G NR RAN 120, UE 110 may send corresponding credential information to associate with 5G NR RAN 120. More specifically, UE 110 may associate with a specific cell (e.g., gNB 120A).

[0025] As described above, the exemplary embodiments relate to DSS. Therefore, reference to a single 5G NR RAN 120 and a single LTE RAN 122 is provided for illustrative purposes only. In some embodiments, a single RAN may be configured to deploy both LTE RAT and 5G NR RAT. In other embodiments, there may be multiple RANs deployed with overlapping coverage areas. Similarly, for illustrative purposes, reference to a single gNB 120A and a single eNB 122A is also provided. In some embodiments, a single base station or cell may be configured for both LTE RAT and 5G NR RAT. In other embodiments, multiple 5G NR base stations and multiple LTE base stations may be deployed with overlapping coverage areas. The exemplary embodiments are not limited to any particular arrangement of RANs and base stations. The exemplary embodiments may be applied to any network arrangement that includes DSS functionality.

[0026] In addition to RANs 120 and 122, network arrangement 100 includes a cellular core network 130, the internet 140, an IP multimedia subsystem (IMS) 150, and a network services backbone 160. Cellular core network 130 may refer to an interconnected collection of components that manage the operation and traffic of a cellular network. It may include an evolved packet core (EPC) and / or a 5G core (5GC). Cellular core network 130 also manages traffic flowing between the cellular network and the internet 140. IMS 150 may generally be described as an architecture for delivering multimedia services to UE 110 using IP protocols. IMS 150 may communicate with cellular core network 130 and the internet 140 to provide multimedia services to UE 110. Network services backbone 160 may communicate directly or indirectly with the internet 140 and cellular core network 130. Network services backbone 160 may generally be described as a collection of components (e.g., servers, network storage arrangements, etc.) that implement a suite of services that may be used to extend the functionality of UE 110 to communicate with various networks.

[0027] Figure 2 An exemplary UE 110 is shown according to various exemplary embodiments. Figure 1100 is used to describe the UE 110 with respect to the network arrangement 100. The UE 110 may include a processor 205, a memory arrangement 210, a display device 215, an input / output (I / O) device 220, a transceiver 225, and other components 230. The other components 230 may include, for example, an audio input device, an audio output device, a power source, a data acquisition device, a port for electrically connecting the UE 110 to other electronic devices, and the like.

[0028] The processor 205 may be configured to execute multiple engines of the UE 110. For example, the engines may include a 5G NR PDCCH rate matching engine 235. The 5G NR PDCCH rate matching engine 235 may be configured to implement various exemplary rate matching techniques related to 5G NR PDCCH reception.

[0029] The engine 235 described above is provided as an application (e.g., a program) executed by the processor 205 for illustrative purposes only. The functionality associated with the engine 235 may also be represented as a separate, integrated component of the UE 110, or may be a modular component coupled to the UE 110, such as an integrated circuit with or without firmware. For example, an integrated circuit may include input circuits for receiving signals and processing circuits for processing signals and other information. The engine may also be embodied as an application or a standalone application. In addition, in some UEs, the functionality described for the processor 205 is split between two or more processors, such as a baseband processor and an application processor. The exemplary embodiments may be implemented in any of these or other configurations of the UE.

[0030] The memory arrangement 210 may be a hardware component configured to store data related to operations performed by the UE 110. The display device 215 may be a hardware component configured to display data to a user, and the I / O device 220 may be a hardware component that enables user input. The display device 215 and the I / O device 220 may be separate components or may be integrated together (such as a touch screen). The transceiver 225 may be a hardware component configured to establish a connection with the 5G NR-RAN 120, LTE-RAN (not shown in the figure), traditional RAN (not shown in the figure), WLAN (not shown in the figure), etc. Therefore, the transceiver 225 can operate on multiple different frequencies or channels (e.g., a set of consecutive frequencies).

[0031] Figure 3 An exemplary base station 300 is shown in accordance with various exemplary embodiments. Base station 300 may represent gNB 120A or any other access node that UE 110 may use to establish a connection and manage network operations.

[0032] The base station 300 may include a processor 305, a memory arrangement 310, input / output (I / O) devices 315, a transceiver 320, and other components 325. These other components 325 may include, for example, an audio input device, an audio output device, a battery, a data acquisition device, ports for electrically connecting the base station 300 to other electronic devices and / or a power source, and the like.

[0033] Processor 305 may be configured to execute multiple engines of base station 300. For example, these engines may include DSS engine 330. DSS engine 330 may be configured to perform operations such as, but not limited to, sending configuration information for 5G NRPDDCH rate matching to UE 110, sending on the PDCCH, and puncturing PDCCH REs that collide with LTE CRS.

[0034] The engine 330 described above as an application (e.g., a program) executed by the processor 305 is merely exemplary. The functionality associated with the engine 330 may also be represented as a separate, integrated component of the base station 300, or may be a modular component coupled to the base station 300, such as an integrated circuit with or without firmware. For example, an integrated circuit may include input circuitry for receiving signals and processing circuitry for processing signals and other information. Furthermore, in some base stations, the functionality described for the processor 305 is split between multiple processors (e.g., a baseband processor, an application processor, etc.). The exemplary embodiments may be implemented in any of these or other configurations of the base station.

[0035] The memory 310 may be a hardware component configured to store data related to operations performed by the base station 300. The I / O device 315 may be a hardware component or port that enables a user to interact with the base station 300. The transceiver 320 may be a hardware component configured to exchange data with the UE 110 and any other UE in the network arrangement 100. The transceiver 320 may operate on a variety of different frequencies or channels (e.g., a set of contiguous frequencies). Thus, the transceiver 320 may include one or more components (e.g., radio components) to enable data exchange with various networks and UEs.

[0036] First, the following Figure 4 Method 400 provides a general overview of an example scenario in which UE 110 performs PDCCH rate matching. This example scenario provides context for various example techniques described herein. Some of the example techniques relate to when or under what conditions rate matching around LTE CRS is performed for PDCCH reception. Other example techniques relate to collision handling for 5G NR PDCCH and LTE CRS.

[0037] Figure 4A method 400 for PDCCH reception according to various exemplary embodiments is shown. Figure 1 The network arrangement 100 and Figure 2 The method 400 is described with reference to the UE 110.

[0038] At 405, UE 110 is camped on or served by a cell of a 5G NR RAT. For example, UE 110 may be connected to gNB 120A of 5G NR RAN 120. 5G NR RAT may be deployed on the same frequency band as LTE RAT. Therefore, a deployment scenario may arise in which the 5G NR PDCCH is configured to use the same frequency band as the LTE CRS.

[0039] In 410, UE 110 identifies the reference signal opportunities for the LTE RAT. In other words, UE 110 identifies the mode (or rate) to be used by the LTE cell (e.g., eNB 122A) to transmit LTE CRS on the frequency band of the currently camped 5G NR cell.

[0040] UE 110 may not need to detect the presence and pattern of LTE CRS to be transmitted on the same frequency band as the cell deployed by gNB 120A. Instead, in some examples, coexistence information may be provided by the 5G NR cell, which explicitly or implicitly indicates the pattern (or rate) to be used by the LTE cell to transmit LTE CRS. This coexistence information may enable UE 110 to identify the frequency and / or time locations at which the LTE cell may transmit one or more types of LTE downlink reference signals (e.g., LTE CRS). UE 110 may receive this coexistence information from the 5G NR cell during radio resource control (RRC) signaling or from any other suitable source. Thus, a cell of a first RAT may provide coexistence information to a UE associated with a second, different RAT. However, exemplary embodiments are not limited to scenarios in which information regarding the configuration of LTE CRS is explicitly or implicitly provided to UE 110 from the network. Exemplary embodiments may collect information associated with the pattern (or rate) to be used by the LTE cell to transmit LTE reference signals from any suitable source or sources external or internal to UE 110.

[0041] In 415, UE 110 performs PDCCH rate matching around the LTE CRS. For example, UE 110 may receive downlink control information (DCI) via a 5G NR PDCCH. Since UE 110 knows the mode (or rate) being used to transmit LTE CRS in the frequency band of the currently camped / served 5G NR cell, UE 110 may perform rate matching around the LTE CRS during 5G NR PDCCH reception. Those skilled in the art will understand that, in general, rate matching is a processing technique that includes demapping one or more symbols of a downlink signal and skipping identified reference signal (e.g., LTE CRS) opportunities during the demapping operation.

[0042] UE 110 can configure its baseband processor to perform rate matching around the LTE CRS based on certain conditions. Thus, when a first set of one or more conditions are met, UE 110 can be configured to perform rate matching around the LTE CRS, and when a second set of one or more conditions are met, UE 110 can be constrained to perform rate matching around the LTE CRS. Specific examples of when and / or under what conditions UE 110 may perform rate matching around the LTE CRS are described in more detail below.

[0043] According to some aspects, 5G NR PDCCH rate matching for LTE CRS can be configured per NR search space. Those skilled in the art will appreciate that UE 110 can be configured to receive 5G NR PDCCH in a specific search space. The search space can be a common search space (CSS) configured to be shared by multiple UEs or a UE-specific search space (USS) configured on a per-UE basis. When processing the CSS or USS, UE 110 can configure its baseband processor to perform rate matching around LTE CRS for 5G NR PDCCH reception. The examples provided below describe various conditions related to different aspects of the 5G NR search space that can provide a basis for UE 110 to decide whether to perform PDCCH rate matching when processing the search space.

[0044] UE 110 may be configured by the network to perform PDCCH rate matching when processing specific search spaces. For example, UE 110 may receive an RRC message from gNB 120A that includes configuration information for different search spaces. The RRC message may include a "SearchSpace" information element (IE), which may define how and where UE 110 will search for PDCCH candidates. Example embodiments include an indication for this SearchSpace IE that indicates whether PDCCH rate matching around the LTE CRS is to be performed for the corresponding search space. Figure 5An example of an Abstract Syntax Notation One (ASN.1) for a SearchSpace IE that may be used to configure UE 110 to perform PDCCH rate matching around LTE CRS during PDCCH reception is shown.

[0045] The RRC message may also include a PDCCH-Config IE and / or a PDCCH-ConfigCommon IE, which may be used to configure PDCCH-related operations at UE 110. The exemplary embodiment introduces an indication to the PDCCH-Config IE and / or the PDCCH-ConfigCommon IE that indicates whether PDCCH rate matching around the LTE CRS is to be performed for the corresponding search space. Alternatively, or in addition to the network configuration, the UE 110 may be pre-configured with a predetermined rule that provides a basis for the UE 110 to determine whether to perform PDCCH rate matching on a specific search space. For example, the predetermined rules for PDCCH rate matching around the LTE CRS may be hard-coded in various 3GPP specifications. Therefore, the exemplary embodiment may perform PDCCH rate matching around the LTE CRS based on network configured parameters, pre-configured information, a combination thereof, or any other appropriate factors.

[0046] In some embodiments, the UE 110 may be pre-configured with one or more of the following predetermined rules based on RRC parameters. For example, as indicated above, the UE 110 may receive an RRC message including a SearchSpace IE. The content of this IE may provide a basis for the UE 110 to determine whether to perform PDCCH rate matching during PDCCH reception on the corresponding search space. For NR CSS, when the SearchSpaceType IE of the SearchSpace IE is configured as "common", or when the SearchSpaceType-r16 IE of the SearchSpace IE is configured as "common-r16", the UE 110 may constrain its baseband processor to perform PDCCH rate matching. For NR USS, when the SearchSpaceType IE of the SearchSpace IE is configured as "ue-Specific", the UE 110 may configure its baseband processor to perform PDCCH rate matching. These predetermined rules can be used for DSS without placing unreasonable demands on the UE or the network.

[0047] The network may also configure UE 110 to perform PDCCH rate matching around certain LTE CRS patterns using coexistence information or any other suitable type of configuration information. For example, the network may send configuration information including the LTE CRS pattern to UE 110 using RRC IEs such as "ServingCellConfig" and "ServingCellConfigCommon". An exemplary embodiment introduces an IE that may be provided as part of the ServingCellConfig IE and / or the ServingCellConfigCommon IE that configures UE 110 to perform PDCCH rate matching around one or more specific LTE CRS patterns. The exemplary IE may be implemented as "lte-CRS-ToMatchAround", "lte-CRS-PatternList-r16", "lte-CRS-PatternList2-r16", or may be identified in any other suitable manner. Thus, UE 110 may configure its baseband processor to perform PDCCH rate matching around the LTE CRS pattern based on the indication provided in the LTE CRS pattern configuration information (e.g., ServingCellConfig, ServingCellConfigCommon, etc.).

[0048] The network may use RRC signaling to configure more than one LTE CRS pattern at UE 110. Subsequently, the network may utilize a MAC CE to dynamically activate and deactivate PDCCH rate matching for the configured LTE CRS patterns. The exemplary MAC CE may include a serving cell index, a bitmap including (N) bits, each bit of which corresponds to an LTE CRS pattern, and zero or more reserved bits. If a bit of the bitmap is set to a first value (e.g., 1), UE 110 may configure its baseband processor to perform PDCCH and / or PDSCH rate matching around the corresponding LTE CRS pattern. If a bit of the bitmap is set to a second value (e.g., 0), UE 110 may configure its baseband processor to be constrained to perform PDCCH and / or PDSCH rate matching around the corresponding LTE CRS pattern. Thus, UE 110 may configure its baseband processor to perform PDCCH rate matching around the LTE CRS pattern based on the indication provided in the MAC CE.

[0049] The exemplary embodiments also introduce conflict handling techniques for 5G NRPDCCH and LTE CRS that can be implemented on the UE 110 side and / or the gNB 120A side. Before discussing these exemplary techniques, the following is a brief description of the conflict handling techniques for 5G NRPDCCH and LTE CRS. Figures 6 and 7A general overview of LTE CRS design and NR PDCCH design at the resource element (RE) level is provided.

[0050] Figure 6 Examples of exemplary LTE CRS designs according to various exemplary embodiments are shown. Example 610 illustrates a slot configuration for a 1-port LTE CRS at the RE level, Example 620 illustrates a slot configuration for a 2-port LTE CRS at the RE level, and Example 630 illustrates a slot configuration for a 4-port LTE CRS. Each of Examples 610 to 630 illustrates a slot having symbols indexed 0 to 13 and subcarriers indexed 0 to 11.

[0051] A 1-port LTE CRS may occupy symbols {0, 4, 7, 11} of a time slot, and within each of these symbols, the CRS may be located at every 6 REs. In example 610, the LTE CRS is shown as being located on subcarriers 5 and 11 of symbol 0, subcarriers 2 and 8 of symbol 4, subcarriers 5 and 11 of symbol 7, and subcarriers 2 and 8 of symbol 11. However, the exemplary embodiment is not limited to arranging the LTE CRS within a symbol in this manner. Therefore, in actual operational scenarios, the subcarrier position of the CRS within a symbol may be shifted up or down, but the number of REs between each CRS within a time slot may be the same.

[0052] The 2-port LTE CRS may occupy symbols {0, 4, 7, 11} of a time slot, and within each of these symbols, the CRS may be located at every 3 REs. In example 620, the LTE CRS is shown as being located on subcarriers 2, 5, 8, and 11 of symbol 0, subcarriers 2, 5, 8, and 11 of symbol 4, subcarriers 2, 5, 8, and 11 of symbol 7, and subcarriers 2, 5, 8, and 11 of symbol 11. However, the exemplary embodiment is not limited to arranging the LTE CRS within a symbol in this manner. Therefore, in actual operational scenarios, the subcarrier position of the CRS within a symbol may be shifted up or down, but the number of REs between each CRS within a time slot may be the same.

[0053] A 4-port LTE CRS may occupy symbols {0, 1, 4, 7, 8, 11} of a timeslot, and within each of these symbols, the CRS may be located at every 3 REs. In example 630, the LTE CRS is shown as being located on subcarriers 2, 5, 8, and 11 of symbol 0, subcarriers 2, 5, 8, and 11 of symbol 1, subcarriers 2, 5, 8, and 11 of symbol 4, subcarriers 2, 5, 8, and 11 of symbol 7, subcarriers 2, 5, 8, and 11 of symbol 8, and subcarriers 2, 5, 8, and 11 of symbol 11. However, the exemplary embodiment is not limited to arranging the LTE CRS within a symbol in this manner. Therefore, in actual operational scenarios, the subcarrier position of the CRS within a symbol may be shifted up or down, but the number of REs between each CRS within a timeslot may be the same.

[0054] Figure 7 An example of a PDCCH demodulation reference signal (DMRS) design according to various exemplary embodiments is shown. In this example, the PDCCH occupies 3 symbols indexed from 0 to 2 and twelve subcarriers indexed from 0 to 11. DMRS is included in each PDCCH symbol, and within each symbol, DMRS is located at every 4 REs. However, the exemplary embodiments are not limited to arranging the PDCCH DMRS within a symbol in this manner. Therefore, in actual operation scenarios, the subcarrier position of the DMRS within a symbol may be shifted up or down, but the number of REs between each CRS within a time slot may be the same.

[0055] Under normal circumstances, NR PDCCH candidates may not be expected to collide with LTE CRS, and UE 110 does not need to monitor NR PDCCH that collides with LTE CRS. It has been recognized that in actual deployment scenarios, this type of behavior may constrain the 5G NR network to use 2-symbol and 3-symbol control resource sets (CORESETs), which may have a negative impact on NR scheduling flexibility and control reliability. According to some exemplary aspects, contrary to traditional methods, the exemplary techniques described below assume that UE 110 needs to decode the corresponding PDCCH candidate. In addition, the exemplary embodiments support 5G NR PDCCH reception in symbols with LTE CRS.

[0056] When LTE CRS collides with NR PDCCH data within a symbol, UE 110 may decode the corresponding PDCCH candidate. UE 110 may identify the collision based on coexistence information, control information scheduling the PDCCH data, and / or any other appropriate factors. In some embodiments, on the network side, gNB 120A transmits PDCCH data even if the PDCCH data collides with LTE CRS within a symbol. While this may cause interference, it is unlikely to be severe enough to cause performance degradation.

[0057] In other embodiments, PDCCH data REs that collide with LTE CRS are punctured at gNB 120A and, therefore, may not actually be transmitted. UE 110 may perform rate matching on PDCCH data REs that collide with LTE CRS within a symbol and also puncture them. However, references to puncturing are provided for illustrative purposes only, and different entities may refer to similar concepts by different names. Furthermore, the exemplary embodiments are not limited to puncturing, and any suitable type of rate matching technique may be used for PDCCH data REs when they collide with LTE CRS within a symbol.

[0058] Figure 8 An example of a collision handling technique for intra-symbol collisions between 5G NR PDCCH data and LTE CRS is shown, according to various exemplary embodiments. In example 810, symbol 812 includes LTE CRS occupying subcarriers 2, 8, and 11, and symbol 814 includes NR PDCCH with PDCCH data and DMRS. Although depicted as adjacent to each other, symbols 812 and 814 can be configured for simultaneous transmission. In this example, the LTE CRS collides with the PDCCH data. However, the NR PDCCH data is still transmitted by gNB 120A, and no rate matching is performed at UE 110.

[0059] In example 820, symbol 822 includes LTE CRS occupying subcarriers 2, 8, and 11, and symbol 824 includes NR PDCCH with PDCCH data and DMRS. Although depicted as adjacent to each other, symbols 822 and 824 may be configured for simultaneous transmission. In this example, the LTE CRS collides with the PDCCH data. gNB 120A may puncture the PDCCH data that collides with the LTE CRS and, therefore, may not actually send the punctured PDCCH data to UE 110. UE 110 may also perform rate matching and puncture the PDCCH data that collides with the LTE CRS.

[0060] When LTE CRS collides with NR PDCCH DMRS within a symbol, UE 110 may decode the corresponding PDCCH candidate. UE 110 may identify the collision based on coexistence information, control information scheduling the PDCCH data, and / or any other appropriate factors. In some embodiments, on the network side, gNB 120A transmits PDCCH DMRS even if the PDCCH data collides with LTE CRS within a symbol. In other words, gNB 120A does not perform puncturing, and UE 110 does not perform rate matching / puncturing. While this may cause interference, it is unlikely to be severe enough to cause performance degradation.

[0061] In other embodiments, the PDCCH DMRS REs that collide with the LTE CRS are punctured at gNB 120A, and thus the PDCCH data REs may not actually be transmitted. UE 110 may rate-match and also puncture the PDCCH DMRS that collide with the LTE CRS within a symbol. In yet another embodiment, all PDCCH DMRS within a symbol may be punctured at gNB 120A and UE 110 when at least one PDCCH DMRS collides with an LTE CRS. However, references to puncturing are provided for illustrative purposes only, and different entities may refer to similar concepts by different names. Furthermore, the exemplary embodiments are not limited to puncturing, and any suitable type of rate matching technique may be used for PDCCH data REs when they collide with LTE CRS within a symbol.

[0062] Figure 9 An example of a collision handling technique for intra-symbol collisions between 5G NR PDCCH DMRS and LTE CRS is shown, according to various exemplary embodiments. In example 910, symbol 912 includes LTE CRS occupying subcarriers 2, 8, and 11, and symbol 914 includes NR PDCCH with PDCCH data and DMRS. Although depicted as adjacent to each other, symbols 912 and 914 can be configured for simultaneous transmission. In this example, the LTE CRS collides with the PDCCH DMRS. However, the NR PDCCH data is still transmitted by gNB 120A, and no rate matching is performed at UE 110.

[0063] In example 920, symbol 922 includes LTE CRS occupying subcarriers 2, 8, and 11, and symbol 924 includes NR PDCCH with PDCCH data and DMRS. Although depicted as adjacent to each other, symbols 922 and 924 may be configured for simultaneous transmission. In this example, the LTE CRS collides with a single PDCCH DMRS. gNB 120A may puncture the PDCCH DMRS that collides with the LTE CRS and, therefore, may not actually transmit the punctured PDCCH DMRS to UE 110. UE 110 may also rate match and puncture the PDCCH DMRS that collides with the LTE CRS.

[0064] In example 930, symbol 932 includes LTE CRS occupying subcarriers 2, 8, and 11, and symbol 923 includes NR PDCCH with PDCCH data and DMRS. Although depicted as adjacent to each other, symbols 932 and 934 may be configured for simultaneous transmission. In this example, the LTE CRS collides with a single PDCCH DMRS. gNB 120A may puncture each of the PDCCH DMRS and, therefore, may not actually transmit the punctured PDCCH DMRS to UE 110. In this example, the PDCCH DMRS is punctured even though only one of the PDCCH DMRS REs collides with the LTE CRS. UE 110 may also perform rate matching and puncture all PDCCH DMRS within the symbol.

[0065] In some exemplary embodiments, when all PDCCH DMRS in a symbol are punctured, the PDCCH DMRS REs that do not collide with LTE CRS REs may be replaced by NR PDCCH data REs. For example, in example 930, only the PDCCH DMRS on subcarrier 5 collides with the LTE CRS, but all PDCCH DMRS within the symbol are punctured. gNB 120A may send PDCCH data on REs on subcarriers 1 and 9 instead of sending Figure 9 In other embodiments, nothing is sent on PDCCH DMRS REs that do not collide with LTE CRS. For example, in example 930, only the PDCCH DMRS on subcarrier 5 collides with LTE CRS, but all PDCCH DMRS within the symbol are punctured. gNB 120A may send neither PDCCH DMRS nor PDCCH data on REs of subcarriers 1 and 9, instead of sending Figure 9 PDCCH DMRS shown.

[0066] According to some aspects, all PDCCH DMRS within symbols where at least one PDCCH DMRS collides with an LTE CRS may be punctured only when certain conditions exist (e.g., example 930). Otherwise, the gNB 120A may puncture only the PDCCH DMRS that collide with the LTE CRS (e.g., example 920), or the gNB 120A may not puncture any PDCCH DMRS (e.g., example 910). For example, for a resource element group (REG) bundle in which at least one NRPDCCH DMRS RE collides with an LTE CRS, when the REG bundle is used for a transparent PDCCH subband (e.g., frequency selective precoding), DMRS from the REG bundle that do not collide with the DMRS may be punctured. In another example, when the precoderGranularity IE in the ControlResourceSet IE is configured as "allContiguousRBs" and the REG bundle size includes all REs of the ControlResourceSet, DMRS from the REG bundle that do not collide with the DMRS can be punctured. In another example, when the precoderGranularity IE in the ControlResourceSet IE is configured as "sameAsREG-bundle", and if the cce-REG-MappingType IE in the ControlResourceSet IE is configured as "nonInterleaved", or if the cce-REG-MappingType IE in the ControlResourceSet IE is configured as "interleaved", and the REG bundle size is configured by the reg-BundleSize IE in the ControlResourceSet IE, DMRS from the REG bundle that do not collide with the DMRS can be punctured.

[0067] According to other aspects, the direct current (DC) carrier may provide a basis for whether UE 110 performs PDCCH rate matching around LTE CRS. Those skilled in the art will appreciate that LTE DC may result in a shift of one tone of NR because LTE punctures LTE DC while NR does not puncture NR DC. Therefore, if UE 110 needs to perform NR PDCCH rate matching around LTE CRS, the corresponding NR CORESET may not overlap with LTE DC in the frequency domain. Instead, the NR CORESET may be completely above LTE DC in the frequency domain or completely below LTE DC in the frequency domain.

[0068] Among other things, the subcarrier spacing (SCS) may provide a basis for whether or not UE 110 performs PDCCH rate matching around LTE CRS. In some embodiments, UE 110 may need to rate match around LTE CRS during PDCCH reception only when the NR PDCCH is configured with a 15 kilohertz (kHz) SCS.

[0069] In further aspects, when the NR PDCCH is configured for rate matching around LTE CRS, for control channel elements (CCEs) where one or more or all DMRS REs are punctured due to LTE CRS, the CCS may be considered in the PDCCH processing complexity with respect to the maximum number of non-overlapping CCEs that can be supported by UE 110. In other embodiments, when the NR PDCCH is configured for rate matching around LTE CRS, for control channel elements (CCEs) where one or more or all DMRS REs are punctured due to LTE CRS, the CCE may not be considered in the PDCCH processing complexity with respect to the maximum number of non-overlapping CCEs that can be supported by UE 110.

[0070] Example

[0071] In a first embodiment, a method performed by a user equipment (UE) includes receiving information associated with a downlink reference signal for a first radio access technology (RAT), wherein the first RAT is different from a currently serving second RAT; identifying a reference signal opportunity for the downlink reference signal; and receiving downlink control information (DCI) from the second RAT via a physical downlink control channel (PDCCH), wherein one or more DCIs and one or more reference signal opportunities occupy the same symbol.

[0072] In a second embodiment, according to the method described in the first embodiment, the method further includes: identifying the type of search space used for the PDCCH; when the type of the search space is a common search space (CSS), constraining rate matching around the downlink reference signal of the first RAT; and when the type of the search space is a UE-specific search space (USS), performing rate matching around the downlink reference signal of the first RAT.

[0073] In a third embodiment, according to the method of the first embodiment, the method further includes: receiving a radio resource control (RRC) SearchSpace information element (IE), wherein the SearchSpace IE indicates whether the UE will perform rate matching for a corresponding search space around the downlink reference signal of the first RAT.

[0074] In a fourth embodiment, according to the method of the first embodiment, the method further includes: receiving a radio resource control (RRC) message including an information element (IE), wherein the IE is one of a PDCCH-Config IE or a PDCCH-ConfigCommon IE, and wherein the IE indicates whether the UE will perform rate matching around the downlink reference signal of the first RAT for a corresponding search space.

[0075] In a fifth embodiment, the method according to the first embodiment is characterized in that the UE is configured to perform rate matching around one or more downlink reference signal patterns according to a SearchSpace information element (IE).

[0076] In a sixth embodiment, according to the method described in the first embodiment, the method also includes: receiving a radio resource control (RRC) message, which configures more than one downlink reference signal mode; and receiving a medium access control (MAC) control element (CE), which is configured to activate and deactivate rate matching around each downlink reference signal mode in the more than one downlink reference signal modes.

[0077] In a seventh embodiment, the method according to the sixth embodiment, wherein the MAC CE includes a bitmap, and wherein each bit of the bitmap corresponds to a different downlink reference signal pattern.

[0078] In an eighth embodiment, according to the method described in the first embodiment, the method also includes: identifying one or more PDCCH data resource elements (REs) that conflict with the downlink reference signal; and truncating each PDCCH data RE in the identified one or more PDCCH data REs.

[0079] In a ninth embodiment, according to the method of the first embodiment, the method further comprises: identifying one or more PDCCH demodulation reference signal (DMRS) resource elements (REs) in the same symbol or slot that each collide with a different downlink reference signal.

[0080] In a tenth embodiment, the method according to the ninth embodiment, wherein at least one PDCCH DMRS RE in the same symbol or slot does not collide with a downlink reference signal, and wherein all PDCCH DMRS REs in the same symbol or slot are punctured.

[0081] In an eleventh embodiment, the method according to the tenth embodiment, wherein PDCCH data is sent to replace the at least one PDCCH DMRS RE that does not collide with the downlink reference signal in the same symbol or slot.

[0082] In a twelfth embodiment, the method according to the tenth embodiment, wherein puncturing of all PDCCH DMRS REs in the same symbol or slot is restricted to resource element groups (REGs) in which at least one PDCCH DMRS colliding with the downlink reference signal exists.

[0083] In a thirteenth embodiment, the method according to the twelfth embodiment, wherein the puncturing of all PDCCH DMRS REs in the same symbol or time slot is further constrained to one or more of the following predetermined conditions: i) the REG bundle is used for a transparent PDCCH subband, ii) the predecoder granularity is configured as all consecutive resource blocks, and iii) the predecoder granularity is configured to be the same as the REG bundle.

[0084] In a fourteenth embodiment, the method according to the ninth embodiment, wherein at least one PDCCH DMRS RE in the same symbol or slot does not collide with a downlink reference signal, and wherein the identified one or more DMRS REs are punctured.

[0085] In a fifteenth embodiment, the method according to the first embodiment is provided, wherein when a control resource set (CORESET) does not overlap with a direct current (DC) carrier of the first RAT in the frequency domain, PDCCH rate matching around the downlink reference signal is configured to be performed, and wherein when the CORESET overlaps with the DC carrier of the first RAT in the frequency domain, the PDCCH rate matching around the downlink reference signal is constrained to be performed.

[0086] In a sixteenth embodiment, according to the method described in the first embodiment, the method also includes: truncating one or more demodulation reference signals (DMRS) of a control channel element (CCE), wherein the CCE is taken into account for PDCCH processing complexity when determining the maximum number of non-overlapping CCEs that the UE can support.

[0087] In a seventeenth embodiment, according to the method described in the first embodiment, the method also includes: truncating one or more demodulation reference signals (DMRS) of a control channel element (CCE), wherein the CCE is not considered for PDCCH processing complexity when determining the maximum number of non-overlapping CCEs that the UE can support.

[0088] In an eighteenth embodiment, a processor of a user equipment (UE) is configured to perform any of the operations described in accordance with the first to seventeenth embodiments.

[0089] In a nineteenth embodiment, a user equipment (UE) includes: a transceiver configured to communicate with a network; and a processor communicatively coupled to the transceiver and configured to perform any of the operations described in accordance with the first to seventeenth embodiments.

[0090] In a twentieth embodiment, a method performed by a base station comprises: identifying a reference signal opportunity for a downlink reference signal of a first radio access technology (RAT); and sending downlink control information (DCI) to a user equipment (UE) via a physical downlink control channel (PDCCH) of a second RAT, wherein one or more DCIs and one or more reference signal opportunities occupy the same symbol.

[0091] In a twenty-first embodiment, according to the method of the twentieth embodiment, the method further includes: sending a radio resource control (RRC) SearchSpace information element (IE) to the UE, wherein the SearchSpace IE indicates whether the UE will perform rate matching for the corresponding search space around the downlink reference signal of the first RAT.

[0092] In a twenty-second embodiment, according to the method of the twentieth embodiment, the method further includes: sending a radio resource control (RRC) message including an information element (IE) to the UE, wherein the IE is one of a PDCCH-Config IE or a PDCCH-ConfigCommon IE, and wherein the IE indicates whether the UE will perform rate matching for the corresponding search space around the downlink reference signal of the first RAT.

[0093] In a twenty-third embodiment, according to the method described in the twentieth embodiment, the method further includes: sending a radio resource control (RRC) message to the UE, the RRC message configuring more than one downlink reference signal mode; and sending a medium access control (MAC) control element (CE) to the UE, the medium access control (MAC) control element (CE) being configured to activate and deactivate rate matching performed by the UE around each downlink reference signal mode in the more than one downlink reference signal modes, wherein the MAC CE includes a bitmap, and wherein each bit of the bitmap corresponds to a different downlink reference signal mode.

[0094] In a twenty-fourth embodiment, according to the method described in the twentieth embodiment, the method also includes: identifying one or more PDCCH data resource elements (REs) that conflict with the downlink reference signal; and truncating each PDCCH data RE in the identified one or more PDCCH data REs.

[0095] In a twenty-fifth embodiment, according to the method of the twentieth embodiment, the method further includes: identifying one or more PDCCH demodulation reference signal (DMRS) resource elements (REs) in the same symbol or time slot that each conflict with a different downlink reference signal.

[0096] In a twenty-sixth embodiment, the method according to the twenty-fifth embodiment, wherein at least one PDCCH DMRS RE in the same symbol or slot does not collide with a downlink reference signal, and wherein all PDCCH DMRS REs in the same symbol or slot are punctured.

[0097] In a twenty-seventh embodiment, the method according to the twenty-sixth embodiment, wherein PDCCH data is sent to replace the at least one PDCCH DMRS RE that does not collide with the downlink reference signal in the same symbol or slot.

[0098] In a twenty-eighth embodiment, the method according to the twenty-sixth embodiment, wherein puncturing of all PDCCH DMRS REs in the same symbol or slot is restricted to resource element groups (REGs) in which there is at least one PDCCH DMRS colliding with the downlink reference signal.

[0099] In a twenty-ninth embodiment, a processor of a base station is configured to perform any operation of the operations described in accordance with the twentieth to twenty-eighth embodiments.

[0100] In a thirtieth embodiment, a base station includes: a transceiver configured to communicate with a user equipment (UE); and a processor communicatively coupled to the transceiver and configured to perform any of the operations described in accordance with the twentieth to twenty-eighth embodiments.

[0101] Those skilled in the art will appreciate that the exemplary embodiments described above can be implemented with any suitable software configuration or hardware configuration or combination thereof. Exemplary hardware platforms for implementing the exemplary embodiments may include, for example, Intel x86-based platforms with compatible operating systems, Windows OS, Mac platforms and MAC OS, mobile devices with operating systems such as iOS, Android, etc. The exemplary embodiments of the above methods may be embodied as a program comprising lines of code stored on a non-transitory computer-readable storage medium, which, when compiled, can be executed on a processor or microprocessor.

[0102] Although this patent application describes various combinations of various embodiments, each with different features, those skilled in the art will understand that any feature of one embodiment may be combined with features of other embodiments in any manner not publicly denied, or with features that are not functionally or logically inconsistent with the operation or described function of the device of the embodiments disclosed herein.

[0103] It is understood that the use of personally identifiable information should be subject to privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and disposed of to minimize the risk of unintentional or unauthorized access or use, and the nature of authorized use should be clearly stated to users.

[0104] It will be apparent to those skilled in the art that various modifications may be made to the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to cover modifications and variations of the present disclosure provided that these modifications and variations are within the scope of the appended claims and their equivalents.

Claims

1. A processor of a user equipment (UE), the processor being configured to perform operations including: receiving information associated with a downlink reference signal for a first radio access technology (RAT), wherein the first RAT is different from a currently serving second RAT; identifying a reference signal opportunity for the downlink reference signal; and Downlink control information (DCI) is received from the second RAT via a physical downlink control channel (PDCCH), wherein one or more DCIs and one or more reference signal opportunities occupy the same symbol.

2. The processor of claim 1 , the operations further comprising: identifying a type of search space for the PDCCH; When the type of the search space is a common search space (CSS), constraining rate matching around the downlink reference signal of the first RAT; and When the type of the search space is a UE-specific search space (USS), rate matching is performed around the downlink reference signal of the first RAT.

3. The processor of claim 1 , the operations further comprising: A radio resource control (RRC) SearchSpace information element (IE) is received, wherein the SearchSpace IE indicates whether the UE is to perform rate matching around the downlink reference signal of the first RAT for a corresponding search space.

4. The processor of claim 1 , the operations further comprising: A radio resource control (RRC) message including an information element (IE) is received, wherein the IE is one of a PDCCH-Config IE or a PDCCH-ConfigCommon IE, and wherein the IE indicates whether the UE is to perform rate matching around the downlink reference signal of the first RAT for a corresponding search space.

5. The processor of claim 1, wherein the UE is configured to perform rate matching around one or more downlink reference signal patterns in accordance with a SearchSpace Information Element (IE).

6. The processor of claim 1, the operations further comprising: receiving a radio resource control (RRC) message, the radio resource control (RRC) message configuring more than one downlink reference signal mode; as well as A medium access control (MAC) control element (CE) is received, the medium access control (MAC) control element (CE) configured to activate and deactivate performing rate matching around each of the more than one downlink reference signal patterns.

7. The processor of claim 6, wherein the MAC CE comprises a bitmap, and wherein each bit of the bitmap corresponds to a different downlink reference signal mode.

8. The processor of claim 1, the operations further comprising: Identifying one or more PDCCH data resource elements (REs) that collide with a downlink reference signal; as well as Each of the identified one or more PDCCH data REs is punctured.

9. The processor of claim 1, the operations further comprising: Identifies one or more PDCCH demodulation reference signal (DMRS) resource elements (REs) in the same symbol or slot that each collide with a different downlink reference signal.

10. The processor of claim 9, wherein at least one PDCCH DMRS RE in the same symbol or slot does not collide with a downlink reference signal, and wherein all PDCCH DMRS REs in the same symbol or slot are punctured.

11. The processor of claim 10, wherein PDCCH data is sent to replace the at least one PDCCH DMRS RE in the same symbol or slot that does not collide with the downlink reference signal.

12. The processor of claim 10, wherein performing puncturing on the all PDCCH DMRS REs in the same symbol or slot is constrained to resource element groups (REGs) in which there is at least one PDCCH DMRS colliding with the downlink reference signal.

13. The processor of claim 12, wherein performing truncation on all PDCCH DMRS REs in the same symbol or time slot is also constrained to one or more of the following predetermined conditions: i) REG bundles are used for transparent PDCCH subbands, ii) predecoder granularity is configured as all consecutive resource blocks, and iii) the predecoder granularity is configured to be the same as the REG bundle.

14. The processor of claim 9, wherein at least one PDCCH DMRS RE in the same symbol or slot does not collide with a downlink reference signal, and wherein the identified one or more DMRS REs are punctured.

15. A processor of a base station, the processor being configured to perform operations comprising: identifying a reference signal opportunity for a downlink reference signal of a first radio access technology (RAT); and Downlink control information (DCI) is sent to a user equipment (UE) via a physical downlink control channel (PDCCH) of the second RAT, wherein one or more DCIs and one or more reference signal opportunities occupy the same symbol.

16. The processor of claim 15, the operations further comprising: A radio resource control (RRC) SearchSpace information element (IE) is sent to the UE, wherein the SearchSpace IE indicates whether the UE is to perform rate matching around the downlink reference signal of the first RAT for a corresponding search space.

17. The processor of claim 15, the operations further comprising: A radio resource control (RRC) message including an information element (IE) is sent to the UE, wherein the IE is one of a PDCCH-Config IE or a PDCCH-ConfigCommon IE, and wherein the IE indicates whether the UE is to perform rate matching around the downlink reference signal of the first RAT for a corresponding search space.

18. The processor of claim 15, the operations further comprising: sending a radio resource control (RRC) message to the UE, the RRC message configuring more than one downlink reference signal mode; as well as A medium access control (MAC) control element (CE) is sent to the UE, wherein the medium access control (MAC) control element (CE) is configured to activate and deactivate rate matching performed by the UE around each of the more than one downlink reference signal patterns, wherein the MAC CE includes a bitmap, and wherein each bit of the bitmap corresponds to a different downlink reference signal pattern.

19. The processor of claim 15, the operations further comprising: Identifying one or more PDCCH data resource elements (REs) that collide with a downlink reference signal; as well as Each of the identified one or more PDCCH data REs is punctured.

20. The processor of claim 15, the operations further comprising: One or more PDCCH demodulation reference signal (DMRS) resource elements (REs) in the same symbol or slot that each collide with a different downlink reference signal are identified.

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