Candidate synchronization signal block transmission resources

Apparatuses, methods, and systems are disclosed for determining candidate synchronization signal block transmission resources. One method (800) includes receiving (802) first information indicating at least one candidate synchronization signal block transmission resource. The at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof. The method (800) includes receiving (804) second information and downlink data corresponding to the second information. The method (800) includes decoding (806) the downlink data. Decoding the downlink data includes rate-matching around the at least one candidate synchronization signal block transmission resource.

FIELD

The subject matter disclosed herein relates generally to wireless communications and more particularly relates to candidate synchronization signal block transmission resources.

BACKGROUND

The following abbreviations are herewith defined, at least some of which are referred to within the following description: Third Generation Partnership Project (“3GPP”), Acknowledge Mode (“AM”), Backhaul (“BH”), Broadcast Multicast (“BM”), Buffer Occupancy (“BO”), Base Station (“BS”), Bandwidth Part (“BWP”), Component Carrier (“CC”), Coordinated Multipoint (“CoMP”), Control Plane (“CP”), CSI-RS Resource Indicator (“CRI”), Channel State Information (“CSI”), Channel Quality Indicator (“CQI”), Central Unit (“CU”), Codeword (“CW”), Downlink (“DL”), Demodulation Reference Signal (“DMRS”), Data Radio Bearer (“DRB”), Distributed Unit (“DU”), Enhanced Mobile Broadband (“eMBB”), Evolved Node B (“eNB”), Enhanced Subscriber Identification Module (“eSIM”), Enhanced (“E”), Frequency Division Duplex (“FDD”), Frequency Division Multiple Access (“FDMA”), Frequency Range (“FR”), Hybrid Automatic Repeat Request (“HARQ”), Integrated Access Backhaul (“IAB”), Identity or Identifier or Identification (“ID”), Interference Measurement (“IM”), International Mobile Subscriber Identity (“IMSI”), Internet-of-Things (“IoT”), Internet Protocol (“IP”), Joint Transmission (“JT”), Level 1 (“L1”), Logical Channel (“LCH”), Logical Channel Prioritization (“LCP”), Long Term Evolution (“LTE”), Multiple Input Multiple Output (“MIMO”), Mobile-Termination (“MT”), Machine Type Communication (“MTC”), Multi-User MIMO (“MU-MIMO”), Negative-Acknowledgment (“NACK”) or (“NAK”), Next Generation (“NG”), Next Generation Node B (“gNB”), New Radio (“NR”), Non-Zero Power (“NZP”), Orthogonal Frequency Division Multiplexing (“OFDM”), Peak-to-Average Power Ratio (“PAPR”), Physical Broadcast Channel (“PBCH”), Physical Downlink Shared Channel (“PDSCH”), Policy Control Function (“PCF”), Packet Data Convergence Protocol (“PDCP”), Packet Data Network (“PDN”), Protocol Data Unit (“PDU”), Public Land Mobile Network (“PLMN”), Precoding Matrix Indicator (“PMI”), Packet Switched (“PS”), Primary Synchronization Signal (“PSS”), Quasi Co-Located (“QCL”), Quality of Service (“QoS”), Radio Access Network (“RAN”), Radio Access Technology (“RAT”), Resource Element (“RE”), Rank Indicator (“RI”), Radio Link Failure (“RLF”), Radio Resource Control (“RRC”), Reference Signal (“RS”), Reference Signal Received Power (“RSRP”), Reference Signal Received Quality (“RSRQ”), Receive (“RX”), Secondary Cell (“SCell”), Service Data Unit (“SDU”), Subscriber Identity Module (“SIM”), Signal-to-Interference and Noise Ratio (“SINR”), Sequence Number (“SN”), Synchronization Signal (“SS”), SS/PBCH Block (“SSB”), Secondary Synchronization Signal (“SSS”), Time Division Multiplexing (“TDM”), Temporary Mobile Subscriber Identity (“TMSI”), Transmission Reception Point (“TRP”), Transmit (“TX”), User Entity/Equipment (Mobile Terminal) (“UE”), Universal Integrated Circuit Card (“UICC”), Uplink (“UL”), Unacknowledged Mode (“UM”), Universal Mobile Telecommunications System (“UMTS”), User Plane (“UP”), Universal Subscriber Identity Module (“USIM”), Universal Terrestrial Radio Access Network (“UTRAN”), Voice Over IP (“VoIP”), Visited Public Land Mobile Network (“VPLMN”), and Worldwide Interoperability for Microwave Access (“WiMAX”). As used herein, “HARQ-ACK” may represent collectively the Positive Acknowledge (“ACK”) and the Negative Acknowledge (“NAK”). ACK means that a TB is correctly received while NAK means a TB is erroneously received.

In certain wireless communications networks, SSBs may be used. In such networks, a device may not know what resources are used for the SSBs.

BRIEF SUMMARY

Methods for determining candidate synchronization signal block transmission resources are disclosed. Apparatuses and systems also perform the functions of the apparatus. In one embodiment, the method includes receiving first information indicating at least one candidate synchronization signal block transmission resource. In such an embodiment, the at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof. In certain embodiments, the method includes receiving second information and downlink data corresponding to the second information. In various embodiments, the method includes decoding the downlink data. In such embodiments, decoding the downlink data includes rate-matching around the at least one candidate synchronization signal block transmission resource.

An apparatus for determining candidate synchronization signal block transmission resources, in one embodiment, includes a receiver that: receives first information indicating at least one candidate synchronization signal block transmission resource, wherein the at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof; and receives second information and downlink data corresponding to the second information. In various embodiments, the apparatus includes a processor that decodes the downlink data. In such embodiments, decoding the downlink data comprises rate-matching around the at least one candidate synchronization signal block transmission resource.

DETAILED DESCRIPTION

FIG.1depicts an embodiment of a wireless communication system100for determining candidate synchronization signal block transmission resources. In one embodiment, the wireless communication system100includes remote units102and network units104. Even though a specific number of remote units102and network units104are depicted inFIG.1, one of skill in the art will recognize that any number of remote units102and network units104may be included in the wireless communication system100.

The network units104may be distributed over a geographic region. In certain embodiments, a network unit104may also be referred to as an access point, an access terminal, a base, a base station, a Node-B, an eNB, a gNB, a Home Node-B, a RAN, a relay node, a device, a network device, an IAB node, a donor IAB node, or by any other terminology used in the art. The network units104are generally part of a radio access network that includes one or more controllers communicably coupled to one or more corresponding network units104. The radio access network is generally communicably coupled to one or more core networks, which may be coupled to other networks, like the Internet and public switched telephone networks, among other networks. These and other elements of radio access and core networks are not illustrated but are well known generally by those having ordinary skill in the art.

In one implementation, the wireless communication system100is compliant with the 5G or NG (Next Generation) of the 3GPP protocol, wherein the network unit104transmits using NG RAN technology. More generally, however, the wireless communication system100may implement some other open or proprietary communication protocol, for example, WiMAX, among other protocols. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

In various embodiments, a remote unit102may determine candidate synchronization signal block transmission resources. In various embodiments, the remote unit102may receive first information indicating at least one candidate synchronization signal block transmission resource. In such an embodiment, the at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof. In certain embodiments, the remote unit102may receive second information and downlink data corresponding to the second information. In various embodiments, the remote unit102may decode the downlink data. In such embodiments, decoding the downlink data includes rate-matching around the at least one candidate synchronization signal block transmission resource. Accordingly, a remote unit102may be used for determining candidate synchronization signal block transmission resources.

In various embodiments, a child node may receive first information indicating at least one candidate synchronization signal block transmission resource from its parent node. In such embodiments, the at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof. In certain embodiments, the child node may receive second information and downlink data corresponding to the second information. In various embodiments, the child node may decode the downlink data. In such embodiments, decoding the downlink data includes rate-matching around the at least one candidate synchronization signal block transmission resource.

In various embodiments, a first remote unit may receive first information indicating at least one candidate synchronization signal block transmission resource from a second remote unit. In such embodiments, the at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof. In certain embodiments, the first remote unite may receive second information and downlink data corresponding to the second information. In various embodiments, the first remote unit may decode the downlink data. In such embodiments, decoding the downlink data includes rate-matching around the at least one candidate synchronization signal block transmission resource.

The processor202, in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor202may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor202executes instructions stored in the memory204to perform the methods and routines described herein. In certain embodiments, the processor202decodes the downlink data. In such embodiments, decoding the downlink data comprises rate-matching around at least one candidate synchronization signal block transmission resource. The processor202is communicatively coupled to the memory204, the input device206, the display208, the transmitter210, and the receiver212.

The transmitter210is used to provide UL communication signals to the network unit104and the receiver212is used to receive DL communication signals from the network unit104. In some embodiments, the receiver212may: receive first information indicating at least one candidate synchronization signal block transmission resource, wherein the at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof; and receive second information and downlink data corresponding to the second information. Although only one transmitter210and one receiver212are illustrated, the remote unit102may have any suitable number of transmitters210and receivers212. The transmitter210and the receiver212may be any suitable type of transmitters and receivers. In one embodiment, the transmitter210and the receiver212may be part of a transceiver.

FIG.3depicts one embodiment of an apparatus300that may be used for transmitting information indicating candidate synchronization signal block transmission resources and/or determining candidate synchronization signal block transmission resources. The apparatus300includes one embodiment of the network unit104. Furthermore, the network unit104may include a processor302, a memory304, an input device306, a display308, a transmitter310, and a receiver312. As may be appreciated, the processor302, the memory304, the input device306, the display308, the transmitter310, and the receiver312may be substantially similar to the processor202, the memory204, the input device206, the display208, the transmitter210, and the receiver212of the remote unit102, respectively.

In various embodiments, the processor302determines candidate synchronization signal block transmission resources. In various embodiments, the transmitter310transmits synchronization signal blocks on the candidate synchronization signal block transmission resources.

Although only one transmitter310and one receiver312are illustrated, the network unit104may have any suitable number of transmitters310and receivers312. The transmitter310and the receiver312may be any suitable type of transmitters and receivers. In one embodiment, the transmitter310and the receiver312may be part of a transceiver.

FIG.4is a schematic block diagram illustrating one embodiment of an integrated access backhaul (“IAB”) system400. The IAB system400includes a first UE402, a second UE404, a first IAB node406, an IAB donor node408, a second IAB node410, a third IAB node412, and a fourth IAB node414. As illustrated, the first UE402is connected to the IAB donor node408via the first IAB node406. Moreover, the second UE404is connected to the IAB donor node408via the second IAB node410, the third IAB node412, and the fourth IAB node414. The IAB system400, as illustrated, may be used for multi-hop backhauling via multiple IAB nodes.

As may be appreciated, multi-hop backhauling systems may provide a larger range extension than single hop systems. This may especially be beneficial for frequencies above 6 GHz due to a limited range of such frequencies. In some configurations, multi-hop backhauling enables backhauling around obstacles (e.g., buildings).

A maximum number of hops in a deployment may depend on many factors such as frequency, cell density, propagation environment, and traffic load. Thus, flexibility in hop count may be desirable. With an increased number of hops, scalability issues may arise, performance may be limited, and/or signaling load may increase signaling load to undesirable levels.

As may be appreciated, wireless backhaul links may be vulnerable to blockage (e.g., due to moving objects such as vehicles, due to seasonal changes (foliage), due to infrastructure changes (new buildings), and so forth). Such vulnerability may also apply to physically stationary IAB-nodes. InFIG.4, the first UE402may switch from communicating via the first IAB node406to communicating with the second IAB node410if a backhaul link is blocked by objects (e.g., moving objects). Moreover, traffic variations may create uneven load distribution on wireless backhaul links leading to local link congestion and/or node congestion.

In some embodiments, an IAB node may include MT and DU. The MT function may be a component of a mobile equipment, or, as used herein, MT may be a function residing on an IAB node that terminates radio interface layers of a backhaul Uu interface toward the IAB-donor or other IAB nodes.

In various embodiments, a gNB may include a gNB-CU and one or more gNB-DUs. Moreover, a gNB-CU and a gNB-DU may be connected via an F1 interface. A gNB-CU may be a gNB central unit that is a logical node hosting RRC, SDAP, and PDCP protocols of the gNB. Furthermore, a gNB-DU may be a gNB distributed unit that is a logical node hosting RLC, MAC, and PHY layers of the gNB. In some embodiments, one cell is supported by only one gNB-DU.

InFIG.4the IAB nodes may be in a standalone mode which includes one IAB-donor and multiple IAB-nodes. The IAB-donor node408may be treated as a single logical node that includes a set of functions such as gNB-DU, gNB-CU-CP, gNB-CU-UP and potentially other functions. In certain embodiments, the IAB-donor node408may be split according to its functions which can all be either collocated or non-collocated as allowed by 3GPP NG-RAN architecture.

In various configurations, there may be collision issues regarding an SSB transmission and transmissions on other channels. The other channels may be PDSCH or other physical RS/channels. As used herein, collision may mean that the same time/frequency resource is used by SSB and other channels/RS. In such configurations, the SSB transmission may have a higher priority than the transmissions on the other channels. So the transmissions on the other channels may be dropped or may adopt rate matching to get around the SSB transmission.

In various embodiments, for both on-raster SSB and off-raster SSB for inter-IAB node measurement, there may be a TDM restriction for an IAB node. The TDM restriction may mean that an IAB node can't transmit and receive at the same time. To solve the half-duplex constraints, variable SSB transmission patterns may be used to make any pair of IAB nodes discovered by each other. With the variable SSB transmission patterns, different IAB nodes may transmit SSB at different time domain offsets. In some embodiments, the SSB transmission occasions within a periodicity may randomly change from periodicity to periodicity to avoid consistent SSB collision of two IAB nodes. In certain embodiments, multiple SSB transmission occasions may be used to provide more chances for inter-IAB node discovery and measurement. In addition, an SSB time domain pattern may be changed over time or between different IAB nodes. As used herein, an SSB can be a single SSB or a SSB set. A single SSB may occupy4symbols, and it may contain PSS, SSS, and/or PBCH. If the SSB is a single SSB, then the transmission occasion may be determined by a time domain starting position of PSS, SSS, and/or PBCH. In this embodiment, determination may mean that if there is an offset value for the SSB, then a smallest value of a starting position of PSS, SSS, and/or PBCH is set to the offset value. If the SSB is an SSB set, there may be multiple SSBs with different indices in a 5 ms time domain window. In this case, a transmission occasion may be determined by a time domain starting position of a first SSB in the SSB set. In this embodiment, the first SSB means an SSB with the smallest SSB index. In this embodiment, determination may mean that if there is an offset value to set the time domain position of the SSB set, then a smallest value of the starting position of PSS, SSS, and/or PBCH of the SSB with the smallest index is set to the offset value.

As may be appreciated, a mechanism may be used to inform a UE of the existence of an SSB for inter-IAB discovery and/or measurement if a gNB schedules PDSCH to the UE. With the knowledge of the existence of the inter-node discovery and/or measurement SSB, the UE may know the scheduled PDSCH is transmitted using rate matching around the SSB so that the UE can correctly decode the PDSCH.

For an IAB node, if an SSB transmitted by an IAB node for an access UE and an SSB for inter-IAB node discovery and/or measurement occupy different time domain resources, additional signaling can be used to indicate whether the SSB is for the access UE or the SSB is for inter-IAB node discovery and/or measurement. In some embodiments, the indication can be made in a MIB by using a reserved bit. In various embodiments, the indication can be made in SIB1 by using reserved bits. Regardless of whether the indication signaling is in MIB or in SIB1, 1 bit signaling can be used to differentiate two states: SSB for an access UE, or SSB for inter-node discovery and/or measurement. Although the described solutions and/or signaling is described in relation to an IAB network. The solution and/or signaling can also be used in a UE to UE network by replacing the IAB node with a UE.

Described herein are various alternatives for indicating to a UE the existence and/or positions of an SSB.

As may be appreciated, differing SSB transmissions may be used to make inter-IAB node discovery and/or measurement possible. In some embodiments, with TDM between backhaul link and access link, an IAB node can't transmit and receive information simultaneously. As a result, for any pair of IAB nodes, there may be two different SSB transmission occasions over a period of time. For example, a first IAB node may transmit at in first time window, and a second IAB node may transmit in a second time window, then the first IAB node can discover and/or measure the SSB of the second IAB node in the second time window, and the second IAB node can discover and/or measure the SSB of first IAB node in the first time window. In this way, the first IAB node and the second IAB node can be discovered and/or measured by each other.

A first option for SSB transmission may include all IAB nodes having different SSB transmission occasions. This option is not scalable if a number of IAB nodes passes a certain threshold because the number of SSB transmission occasions may be limited by an SSB transmission periodicity. For example, if the SSB transmission periodicity is 40 ms and each SSB occupies 5 ms, then there are only 8 different possible offsets for the 5 ms time window. In this example, the SSB transmission periodicity can support at most 8 IAB nodes with different time domain transmission occasions. If the IAB node number to be supported is larger than 8, then at least two IAB nodes need to share the same transmission time domain occasion. Both these two IAB nodes will transmit at the same time, and with TDM restriction, the two IAB nodes can't perform measurement at the same time that they are transmitting. Therefore, these two IAB nodes can't discover and/or measure each other.

A second option for SSB transmission may include each IAB node (or each group of IAB nodes) transmitting multiple times (e.g., twice) during a transmission periodicity. As may be appreciated, if there are N transmission occasions in the transmission periodicity and the number of transmission times for each IAB node or each IAB node group is two, a supportable distinct set number may be C(N,2). Moreover, a supportable IAB node or IAB node group number is also C(N,2). For the second option, different patterns can be used by each IAB node (or each group of IAB nodes). Because any two patterns have at least one non-overlapped time domain position, IAB nodes or IAB node groups using different patterns can discover and/or measure each other. One example is illustrated inFIG.5. The pattern used may have an associated pattern index and each pattern can be used by an IAB node or an IAB node group. The IAB node or IAB node group can be identified by a set ID (or group ID). If the set ID is for a single IAB node, then the set with the set ID has only one IAB node in the set. If the set ID is for an IAB node group, then the set with the set ID has multiple IAB nodes in the set.

FIG.5is a schematic block diagram illustrating one embodiment of SSB transmission patterns500. The transmission patterns500include a first pattern502that may have a pattern index of 1, a second pattern504that may have a pattern index of 2, a third pattern506that may have a pattern index of 3, a fourth pattern508that may have a pattern index of 4, a fifth pattern510that may have a pattern index of 5, and a sixth pattern512that may have a pattern index of 6. Moreover, the first pattern502includes a first TX window514that starts at a first time516, a second TX window518that starts at a second time520, a first RX window522that starts at a third time524, and a second RX window526that starts at a fourth time528. In such an embodiment, a transmission periodicity may start at the first time516and end at a fifth time530. The transmission periodicity may be any suitable time period, such as 60 ms, 80 ms, 160 ms, and so forth. Accordingly, during the transmission periodicity, the first pattern502includes two TX windows and two RX windows. Furthermore, each of the patterns includes two TX windows and two RX windows. Moreover, as may be appreciated, each TX window and each RX window may span a predetermined period of time (e.g., 5 ms, 10 ms, 20 ms, and so forth). Furthermore, a time between the first time516and the second time520(e.g., 5 ms, 10 ms, etc.) may match the time between the second time520and the third time524. In addition, the time between the second time520and the third time524may match the time between the third time524and the fourth time528. Likewise, the time between the third time524and the fourth time528may match the time between the fourth time528and the fifth time530.

The second pattern504includes a first TX window532that starts at the first time516, a first RX window534that starts at the second time520, a second TX window536that starts at the third time524, and a second RX window538that starts at the fourth time528. Moreover, the third pattern506includes a first TX window540that starts at the first time516, a first RX window542that starts at the second time520, a second RX window544that starts at the third time524, and a second TX window546that starts at the fourth time528. Furthermore, the fourth pattern508includes a first RX window548that starts at the first time516, a first TX window550that starts at the second time520, a second TX window552that starts at the third time524, and a second RX window554that starts at the fourth time528.

The fifth pattern510includes a first RX window556that starts at the first time516, a first TX window558that starts at the second time520, a second RX window560that starts at the third time524, and a second TX window562that starts at the fourth time528. Moreover, the sixth pattern512includes a first RX window564that starts at the first time516, a second RX window566that starts at the second time520, a first TX window568that starts at the third time524, and a second TX window570that starts at the fourth time528.

FIG.6is a schematic block diagram illustrating one embodiment of timing600of SSB transmissions with a changing offset.FIG.6is used to illustrate one example of a third option for SSB transmission. A first duration starts at a first time602and ends at a second time604. In the above example, the first time602is 0 ms, and the second time604is 80 ms. In other embodiments, the first duration may be different from 80 ms. For example, the first duration may be 20 ms, 40 ms, 60 ms, 100 ms, 160 ms, and so forth. Moreover, a second duration starts at the second time604and ends at a third time606. In the above example, the second time604is 80 ms, and the third time606is 160 ms. In other embodiments, the second duration may be different from 80 ms. For example, the second SSB duration may be 20 ms, 40 ms, 60 ms, 100 ms, 160 ms, and so forth. Various unused candidate SSB transmission resources608are illustrated.

The third option for SSB transmission may include randomly changing an SSB transmission occasion offset with respect to a starting position. In some embodiments, the SSB transmission occasion offset may be related to an IAB node ID and/or a time index. For example, if an SSB transmission periodicity is 80 ms, a first IAB node may transmit a first SSB (e.g., TX_A) in 0-4 ms and a second SSB (e.g., TX_A) in 85-89 ms in two adjacent SSB transmission periodicities (e.g., the first SSB transmission periodicity starts at 0 ms, and the second SSB transmission periodicity starts at 80 ms, and the offset for the SSB in time window 0-79 ms is 0 and the offset for the SSB in time window 80-159 ms is 5 ms). Moreover, a second IAB node may transmit a first SSB (e.g., TX_B) in 0-4 ms and a second SSB (e.g., TX_B) in 90-94 ms in two adjacent SSB transmission periodicities (the SSB offset in time window 0-79 ms is 0 ms and the SSB offset in time window 80-159 ms is 10 ms). In this example, the first SSB transmission for the first IAB node has an offset of 0 ms with respect to the starting position of the corresponding SSB transmission periodicity, while the second SSB transmission for the first IAB node has an offset of 5 ms with respect to the starting position of the corresponding SSB transmission periodicity. Moreover, the first SSB transmission for the second IAB node has an offset of 0 ms with respect to the starting position of the corresponding SSB transmission periodicity, while the second SSB transmission for the second IAB node has an offset of 10 ms with respect to the starting position of the corresponding SSB transmission periodicity. As may be appreciated, the SSB transmission occasion offset may be changed per SSB transmission periodicity. This example is illustrated inFIG.6. With timely changing the SSB offset, even if two IAB nodes can't discover and/or measure each other in the first SSB transmission duration, the two IAB nodes may have an opportunity for discovery and/or measurement in the second SSB transmission duration.

A fourth option may be a combination of the second option and the third option. In certain embodiments, the second option may be applicable to each IAB node group, and the third option may be applied to each IAB node group. In some embodiments, an IAB node ID and/or time domain index may be used to calculate a group ID (e.g., set ID) for each periodicity (e.g., SSB transmission periodicity). Once the set ID is determined for each periodicity, the SSB time domain transmission offsets can be determined based on the relationship between the set ID and the offsets.

FIG.7is a schematic block diagram illustrating one embodiment of timing700of SSB transmissions in SSB transmission sets. A first duration starts at a first time702and ends at a second time704. In this embodiment, the first time702is 0 ms, and the second time704is 80 ms. In other embodiments, the first duration may be different from 80 ms. For example, the first duration may be 20 ms, 40 ms, 60 ms, 100 ms, 160 ms, and so forth. Moreover, a second duration starts at the second time704and ends at a third time706. In this embodiment, the second time704is 80 ms, and the third time706is 160 ms. In other embodiments, the second duration may be different from 80 ms. For example, the second duration may be 20 ms, 40 ms, 60 ms, 100 ms, 160 ms, and so forth. Various unused candidate SSB transmission resources708are illustrated. As illustrated within the first SSB transmission periodicity, a first IAB node may make first and second transmissions (“TX_A”), a second IAB node may make first and second transmissions (“TX_B”), a third IAB may make first and second transmissions (“TX_C”), and a fourth IAB may make first and second transmissions (“TX_D”). The first and the second IAB nodes share the same time domain pattern, and they can be considered in the same set (e.g., set 1) in the first transmission duration (e.g., time window). The third and the fourth IAB nodes also share the same time domain pattern (e.g., same transmission offsets), and they can also be considered in the same set (e.g. set 2) in the first transmission duration (e.g., time window from 0 to 79 ms).

Furthermore, as illustrated within the second duration (e.g., time window 80-159 ms), the first IAB node may make third and fourth transmissions (“TX_A”), the second IAB node may make third and fourth transmissions (“TX_B”), the third IAB may make first and second transmissions (“TX_C”), and the fourth IAB may make first and second transmissions (“TX_D”). The first and the third IAB nodes share the same time domain offsets, and they can be considered in the same set (e.g., set 1). The second and the fourth IAB nodes share the same time domain offsets, and they can be considered in the same set (e.g., set 2). Therefore, the associated set for the second IAB node is changed from set 1 to set 2, and the time domain offsets of the second IAB node also changed accordingly. For the two IAB nodes, the first IAB node and the second IAB node, although they can't discover and/or measure each other in the first duration, they can discover and/or measure each other in the second duration.

In the illustrated embodiment, similar to the description corresponding toFIG.6, different transmissions from the same IAB may have an offset that changes from one duration to another. For example, the first TX_A has an offset of 0 relative to the first time702, while the third TX_A has an offset different from 0 relative to the second time704(e.g., 10 ms). As another example, the first TX_D has an offset of 0 relative to the first time702, while the third TX_D has an offset different from 0 relative to the second time704(e.g., 5 ms). Furthermore, as illustrated, transmissions from the IABs are grouped together into groups (or sets). For example, a first group712in the first SSB transmission periodicity includes the first and second transmissions TX_A and the first and second transmissions TX_B. As another example, a second group714in the first SSB transmission periodicity includes the first and second transmissions TX_C and the first and second transmissions TX_D. As illustrated, the transmissions within a group follow the same pattern and have the same offset. Moreover, a first group716in the second SSB transmission periodicity includes the first and second transmissions TX_A and the first and second transmissions TX_C. Furthermore, a second group718in the second SSB transmission periodicity includes the first and second transmissions TX_B and the first and second transmissions TX_D. Thus, as illustrated groupings between different SSB transmission periodicities may change.

As may be appreciated, there may be a variety of methods used to indicate a time domain position of a candidate (e.g., possible) SSB transmission to enable a UE to use the position information for rate matching.

In one embodiment, a time domain position of a candidate SSB transmission for inter-IAB discovery and/or measurement may be dynamically indicated by a gNB. In certain embodiment, a set of candidate time domain positions of the SSB transmission for inter-IAB discovery and/or measurement may be configured by RRC signaling transmitted to a UE. In some embodiments, such as those based on the third option described herein, candidate SSB transmission occasions may include all possible SSB offsets if the offset is changed periodically. In certain embodiments, such as those based on the second option and/or the fourth option, candidate SSB transmission occasions may include all possible SSB offsets for all group/set indexes.

In various embodiments, if a UE has a scheduled PDSCH, the UE may detect the existence of one or multiple SSB transmission occasions by a variety of methods. In a first method, the UE may detect the existence of one or multiple SSB transmission occasions using blind decoding. The blind decoding may be based on a PSS, a SSS, a PBCH, and/or a DMRS. In a second method, the UE may detect the existence of one or multiple SSB transmission occasions using additional bits in scheduling DCI that are used to indicate the existence of one or multiple SSB transmission occasions. In such embodiments, the relationship between DCI bits to SSB transmission occasion sets may be configured by RRC signaling. In a third method, the UE may detect the existence of one or multiple SSB transmission occasions using information (e.g., 1 or more bits) in DCI to indicate whether or not there is an SSB transmission occasion for inter-IAB node measurement in the time/frequency resource of the scheduled PDSCH.

In another embodiment, a time domain position of a candidate SSB transmission for inter-IAB discovery and/or measurement may be semi-statically configured by RRC signaling. In some embodiments, such as those based on the second option described herein, for an IAB node set, multiple SSBs may be transmitted in one period and the same SSB transmission patterns may be transmitted in adjacent periods. In such embodiments, an SSB transmission periodicity may be indicated to the UE. As may be appreciated, within a single SSB transmission periodicity, there may be multiple SSB transmission occasions. Furthermore, in such embodiments, a group ID (e.g., set ID) may be indicated to the UE. In some embodiments, an IAB node ID may not be used to generate a group ID because the IAB node ID has other purposes for interference randomization, while the group ID may be used to select several IAB nodes to share the same SSB transmission pattern. Therefore, there may be some coordination based on a network structure, so that the network may determine the group ID for each IAB node. Moreover, a mapping relationship between a group ID and SSB transmission occasions may be predefined in a specification or configured by RRC signaling. As may be appreciated, RRC configuration may be used to adjust a network structure efficiently.

In certain embodiments, such as those based on the third option described herein, one or multiple SSBs may be transmitted in an SSB transmission periodicity. Moreover, a transmission occasion of each SSB may be randomly changed in adjacent SSB transmission periodicities. In such embodiments, a duration may be indicated to a UE. In each duration, there may be one or more SSBs within it, the duration may occur periodically, and adjacent durations may be continuous in the time domain. A timely change of an SSB transmission occasion may mean that the offset of the SSB with respect to the start of each respective duration is changed randomly. In each adjacent duration, the transmission occasion of each SSB may be updated. The duration may be 40 ms, 80 ms, 160 ms, and so forth. In such embodiments, the number of SSB transmission occasions within a duration may be indicted to a UE by RRC signaling. In certain embodiments, an SSB transmission occasion for each SSB within a duration may be decided by parameters such as: an IAB node ID, a time domain index, and/or an SSB transmission occasion index within a duration. In such embodiments, because an IAB node ID and a time domain index may be detected by a UE from system information, there may be no signaling used to indicate these two parameters. In certain embodiments, if different IAB nodes share a same cell ID, another sub-ID to differentiate different IAB nodes may be indicated to UE.

In various embodiments, such as those based on the fourth option described herein, changing a group ID for an IAB node may result in a change to candidate SSB transmission occasions in time domain. In such embodiments, a duration may be indicated to a UE, the duration may be a time domain window, the duration may appear periodically, and adjacent durations may be continuous in the time domain. Being continuous in the time domain may mean that an ending of a duration is also a starting of the next duration. Within each duration, for an IAB node, there are one or multiple SSB transmission occasions corresponding to a set ID. The transmission occasion is determined based on the offset respect to the starting of the corresponding duration. Here corresponding may mean that the SSB is located within the duration. In each adjacent duration, the transmission occasion of each SSB set ID may be updated. As a set ID is associated with one or more SSB transmission occasions, once the set ID is changed, the one or more SSB transmission occasions are changed. Moreover, in such embodiments, a maximum number of group IDs may be indicated to the UE. The maximum number of group IDs may be predefined in a specification or configured by RRC signaling. Furthermore, in such embodiments, a mapping relationship between a group ID and SSB transmission occasions may be predefined in a specification or configured by RRC signaling. In some embodiments, an initial value of a group ID may be indicated to the UE by RRC signaling. In certain embodiments, an IAB node ID and/or a time domain index may be used to determine a group ID per an SSB transmission periodicity.

FIG.8is a schematic flow chart diagram illustrating one embodiment of a method800for determining candidate synchronization signal block transmission resources. In some embodiments, the method800is performed by an apparatus, such as the remote unit102or the network unit104(e.g., IAB node). In certain embodiments, the method800may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

The method800may include receiving802first information indicating at least one candidate synchronization signal block transmission resource. In such an embodiment, the at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof. In certain embodiments, the method800includes receiving804second information and downlink data corresponding to the second information. In various embodiments, the method800includes decoding806the downlink data. In such embodiments, decoding the downlink data includes rate-matching around the at least one candidate synchronization signal block transmission resource.

In various embodiments, the second information comprises scheduling information for scheduling the downlink data. In some embodiments, the method comprises receiving at least one synchronization signal block corresponding to each candidate synchronization signal block transmission resource of the at least one candidate synchronization signal block transmission resource. In certain embodiments, an offset corresponding to the at least one candidate synchronization signal block transmission resource is configured to change at different time instances with respect to a starting position.

In one embodiment, the time instances occur periodically, and a time difference between two adjacent time instances is configured by radio resource signaling. In various embodiments, the starting position is determined by setting the offset equal to zero with respect to a time instance. In some embodiments, a number of candidate synchronization signal block transmission resources of the at least one candidate synchronization signal block transmission resource is configured by radio resource control signaling.

In certain embodiments, an index of a node is configured by radio resource control signaling. In one embodiment, rate-matching around the at least one candidate synchronization signal block transmission resource comprises decoding the downlink data while precluding resource elements used for the at least one candidate synchronization signal block transmission resource. In various embodiments, the first information that indicates the at least one candidate synchronization signal block transmission resource comprises a set index that indicates the at least one candidate synchronization signal block transmission resource.

In some embodiments, the at least one candidate synchronization signal block transmission resource is transmitted periodically based on a periodicity, and the periodicity is configured by radio resource control signaling. In certain embodiments, the set index is indicated by radio resource control signaling. In one embodiment, a relationship between the set index and the at least one candidate synchronization signal block transmission resource is configured by radio resource control signaling.

In various embodiments, a maximum number of sets is configured by radio resource control signaling. In some embodiments, the set index is updatable at each time instance, wherein time instances occur periodically, and a time difference between two adjacent time instances is configurable by radio resource control signaling. In certain embodiments, some synchronization signal blocks corresponding to the at least one candidate synchronization signal block transmission resource are not transmitted.

In one embodiment, rate-matching around the at least one candidate synchronization signal block transmission resource comprises decoding the downlink data while precluding resource elements used for actual synchronization signal block transmission corresponding to the at least one candidate synchronization signal block transmission resource. In various embodiments, the at least one candidate synchronization signal block transmission resource is configured by radio resource control signaling. In some embodiments, actual synchronization signal block transmissions corresponding to the at least one candidate synchronization signal block transmission resource are indicated by downlink control information signaling.

In certain embodiments, downlink control information is used to indicate the actual synchronization signal block transmissions that occur in the same time domain resource of a scheduled physical downlink shared channel. In one embodiment, multiple actually transmitted synchronization signal block sets are configured by radio resource control signaling. In various embodiments, downlink control information is used to select one of the actually transmitted synchronization signal block sets configured by radio resource control signaling.

In one embodiment, a method comprises: receiving first information indicating at least one candidate synchronization signal block transmission resource, wherein the at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof; receiving second information and downlink data corresponding to the second information; and decoding the downlink data, wherein decoding the downlink data comprises rate-matching around the at least one candidate synchronization signal block transmission resource.

In various embodiments, the second information comprises scheduling information for scheduling the downlink data.

In some embodiments, the method comprises receiving at least one synchronization signal block corresponding to each candidate synchronization signal block transmission resource of the at least one candidate synchronization signal block transmission resource.

In certain embodiments, an offset corresponding to the at least one candidate synchronization signal block transmission resource is configured to change at different time instances with respect to a starting position.

In one embodiment, the time instances occur periodically, and a time difference between two adjacent time instances is configured by radio resource signaling.

In various embodiments, the starting position is determined by setting the offset equal to zero with respect to a time instance.

In some embodiments, a number of candidate synchronization signal block transmission resources of the at least one candidate synchronization signal block transmission resource is configured by radio resource control signaling.

In certain embodiments, an index of a node is configured by radio resource control signaling.

In one embodiment, rate-matching around the at least one candidate synchronization signal block transmission resource comprises decoding the downlink data while precluding resource elements used for the at least one candidate synchronization signal block transmission resource.

In various embodiments, the first information that indicates the at least one candidate synchronization signal block transmission resource comprises a set index that indicates the at least one candidate synchronization signal block transmission resource.

In some embodiments, the at least one candidate synchronization signal block transmission resource is transmitted periodically based on a periodicity, and the periodicity is configured by radio resource control signaling.

In certain embodiments, the set index is indicated by radio resource control signaling.

In one embodiment, a relationship between the set index and the at least one candidate synchronization signal block transmission resource is configured by radio resource control signaling.

In various embodiments, a maximum number of sets is configured by radio resource control signaling.

In some embodiments, the set index is updatable at each time instance, wherein time instances occur periodically, and a time difference between two adjacent time instances is configurable by radio resource control signaling.

In certain embodiments, some synchronization signal blocks corresponding to the at least one candidate synchronization signal block transmission resource are not transmitted.

In one embodiment, rate-matching around the at least one candidate synchronization signal block transmission resource comprises decoding the downlink data while precluding resource elements used for actual synchronization signal block transmission corresponding to the at least one candidate synchronization signal block transmission resource.

In various embodiments, the at least one candidate synchronization signal block transmission resource is configured by radio resource control signaling.

In some embodiments, actual synchronization signal block transmissions corresponding to the at least one candidate synchronization signal block transmission resource are indicated by downlink control information signaling.

In certain embodiments, downlink control information is used to indicate the actual synchronization signal block transmissions that occur in the same time domain resource of a scheduled physical downlink shared channel.

In one embodiment, multiple actually transmitted synchronization signal block sets are configured by radio resource control signaling.

In various embodiments, downlink control information is used to select one of the actually transmitted synchronization signal block sets configured by radio resource control signaling.

In one embodiment, an apparatus comprises: a receiver that: receives first information indicating at least one candidate synchronization signal block transmission resource, wherein the at least one candidate synchronization signal block transmission resource is useable for transmitting a synchronization signal block for inter-node discovery, measurement, or a combination thereof; and receives second information and downlink data corresponding to the second information; and a processor that decodes the downlink data, wherein decoding the downlink data comprises rate-matching around the at least one candidate synchronization signal block transmission resource.

In various embodiments, the second information comprises scheduling information for scheduling the downlink data.

In some embodiments, the receiver receives at least one synchronization signal block corresponding to each candidate synchronization signal block transmission resource of the at least one candidate synchronization signal block transmission resource.

In certain embodiments, an offset corresponding to the at least one candidate synchronization signal block transmission resource is configured to change at different time instances with respect to a starting position.

In one embodiment, the time instances occur periodically, and a time difference between two adjacent time instances is configured by radio resource signaling.

In various embodiments, the starting position is determined by setting the offset equal to zero with respect to a time instance.

In some embodiments, a number of candidate synchronization signal block transmission resources of the at least one candidate synchronization signal block transmission resource is configured by radio resource control signaling.

In certain embodiments, an index of a node is configured by radio resource control signaling.

In one embodiment, rate-matching around the at least one candidate synchronization signal block transmission resource comprises decoding the downlink data while precluding resource elements used for the at least one candidate synchronization signal block transmission resource.

In various embodiments, the first information that indicates the at least one candidate synchronization signal block transmission resource comprises a set index that indicates the at least one candidate synchronization signal block transmission resource.

In some embodiments, the at least one candidate synchronization signal block transmission resource is transmitted periodically based on a periodicity, and the periodicity is configured by radio resource control signaling.

In certain embodiments, the set index is indicated by radio resource control signaling.

In one embodiment, a relationship between the set index and the at least one candidate synchronization signal block transmission resource is configured by radio resource control signaling.

In various embodiments, a maximum number of sets is configured by radio resource control signaling.

In some embodiments, the set index is updatable at each time instance, wherein time instances occur periodically, and a time difference between two adjacent time instances is configurable by radio resource control signaling.

In certain embodiments, some synchronization signal blocks corresponding to the at least one candidate synchronization signal block transmission resource are not transmitted.

In one embodiment, rate-matching around the at least one candidate synchronization signal block transmission resource comprises decoding the downlink data while precluding resource elements used for actual synchronization signal block transmission corresponding to the at least one candidate synchronization signal block transmission resource.

In various embodiments, the at least one candidate synchronization signal block transmission resource is configured by radio resource control signaling.

In some embodiments, actual synchronization signal block transmissions corresponding to the at least one candidate synchronization signal block transmission resource are indicated by downlink control information signaling.

In certain embodiments, downlink control information is used to indicate the actual synchronization signal block transmissions that occur in the same time domain resource of a scheduled physical downlink shared channel.

In one embodiment, multiple actually transmitted synchronization signal block sets are configured by radio resource control signaling.

In various embodiments, downlink control information is used to select one of the actually transmitted synchronization signal block sets configured by radio resource control signaling.