Patent Description:
The legacy/known <NUM>-step RA has been used in the <NUM>rd Generation Partnership Project's (3GPP) Long Term Evolution (LTE, also referred to as <NUM>) standards, and is also the baseline for 3GPP New Radio (NR) (NR is also referred to as <NUM>). The general principles of the legacy <NUM>-step radio access channel (RACH) procedure in NR is illustrated in <FIG>, and the steps are described below.

The wireless device (WD) randomly selects a RA preamble (PREAMBLE_INDEX) corresponding to a selected synchronization signal (SS)/physical broadcast channel (PBCH) block, transmits the preamble on the physical random access channel (PRACH) occasion mapped by the selected SS/PBCH block. When the network node detects the preamble, the network node estimates the Timing alignment (TA) the wireless device should use in order to obtain uplink (UL) synchronization at the network node.

The network node sends a RA response (RAR) including the TA, the temporary cell (TC)-radio network temporary identifier (RNTI) (temporary identifier) to be used by the wireless device, a Random Access Preamble identifier that matches the transmitted PREAMBLE_INDEX and a grant for message <NUM> (Msg3, which is part of step <NUM>). The wireless device expects the RAR and thus monitors the physical downlink control channel (PDCCH) addressed to RA-RNTI to receive the RAR message from the network node until the configured RAR window (ra-ResponseWindow) has expired or until the RAR has been successfully received.

According to one or more wireless communication standards such as Third Generation Partnership Project (3GPP) Technical Specification (TS) <NUM>: the medium access control (MAC) entity may stop ra-ResponseWindow and hence monitoring for Random Access Response(s)) after successful reception of a Random Access Response containing Random Access Preamble identifiers that matches the transmitted PREAMBLE_INDEX.

In Msg3, the wireless device (i.e., user equipment (UE)) transmits its identifier (UE ID) for initial access to the network node, or if the wireless device is already in RRC_CONNECTED or RRC_INACTIVE mode and needs to, e.g., resync, the wireless device transmits its UE-specific RNTI.

If the network node cannot decode Msg3 at the granted UL resources, the network node may send downlink control information (DCI) addressed to TC-RNTI for retransmission of Msg3. Hybrid automatic repeat request (HARQ) retransmission is requested until the wireless devices restart the random access procedure from step <NUM> after reaching the maximum number of HARQ retransmissions or until Msg3 can be successfully received by the network node.

In Msg4, the network node responds by acknowledging the UE ID or C-RNTI. The Msg4 gives contention resolution, i.e., only one UE ID or C-RNTI may be sent even if several wireless devices have used the same preamble (and the same grant for Msg3 transmission) simultaneously.

For Msg4 reception, the wireless device monitors TC-RNTI (if the wireless device transmitted its UE ID in Msg3) or C-RNTI (if the wireless device transmitted its C-RNTI in Msg3).

In LTE, the <NUM>-step RA may not be completed in less than a <NUM>/transmission time interval (TTI)/subframe (SF).

The <NUM>-step RA procedure is illustrated in <FIG>. Referring to <FIG>, the <NUM>-step RA provides shorter latency than the ordinary <NUM>-step RA described above. In the <NUM>-step RA, the preamble and a message corresponding to Msg3 (msgA physical uplink shared channel (PUSCH)) in the <NUM>-step RA can, depending on configuration, be transmitted in two subsequent slots. The msgA PUSCH is sent on a resource dedicated to the specific preamble. This means that both the preamble and the Msg3 face contention but contention resolution, in this case, means that either the preamble and Msg <NUM> are sent without collision or both collide.

Upon successful reception msgA, the gNB will respond with a msgB. The msgB may be either a "successRAR", "fallbackRAR or "Back off". The content of msgB has been agreed as seen below. It is noted in particular that fallbackRAR provides a grant for a Msg3 PUSCH that identifies resources in which the UE should transmit the PUSCH, as well as other information. Note: The notations "msgA" and "MsgA" are used interchangeably herein to denote message A. Similarly, the notations "msgB" and "MsgB" are used interchangeably herein to denote message B.

The possibility to replace the <NUM>-step message exchange by a <NUM>-step message exchange may lead to reduced RA latency and fewer listen before talks (LBTs) processes (in case of unlicensed) that may need to be executed. On the other hand, the <NUM>-step RA may consume more resources since <NUM>-step RA uses contention-based transmission of the data. This means that the resources that are configured for the data transmission may often be unused.

If both the <NUM>-step and <NUM>-step RA are configured in a cell on shared PRACH resources (and for the wireless device), the wireless device may choose its preamble from one specific set if the wireless device wants to perform a <NUM>-step RA, and from another set if the wireless device wants to perform a <NUM>-step RA. Hence, a preamble partition is performed to distinguish between <NUM>-step and <NUM>-step RA when shared PRACH resources are used. Alternatively, the PRACH configurations are different for the <NUM>-step and <NUM>-step RA procedure, in which case, it can be deduced from where the preamble transmission is performed if the wireless device is performing a <NUM>-step or <NUM>-step procedure.

In one or more wireless communication standards such as 3GPP Release-<NUM> (Rel-<NUM>), in <NUM>-step RA operation, wireless devices are informed of the potential time-frequency resources where the wireless devices may transmit MsgA PRACH and MsgA PUSCH via higher layer signaling. PRACH is transmitted in periodically recurring RACH occasions ('ROs'), while the physical uplink shared channel (PUSCH) is transmitted in periodically recurring PUSCH occasions ('POs'). PUSCH occasions are described in MsgA PUSCH configurations provided by higher layer signaling. Each MsgA PUSCH configuration defines a starting time of the PUSCH occasions which is measured from the start of a corresponding RACH occasion. Multiple PUSCH occasions may be multiplexed in time and frequency in a MsgA PUSCH configuration, where POs in an orthogonal frequency-division multiplexing (OFDM) symbol occupy a given number of physical resource blocks (PRBs) and are adjacent in frequency, and where POs occupy 'L' contiguous OFDM symbols. POs multiplexed in time in a MsgA PUSCH configuration may be separated by a configured gap 'G' symbols long. The start of the first occupied OFDM symbol in a PUSCH slot is indicated via a start and length indicator value ('SLIV'). The MsgA PUSCH configuration may include multiple contiguous PUSCH slots, each slot containing the same number of POs. The start of the first PRB relative to the first PRB in a bandwidth part (BWP) is also given by the MsgA PUSCH configuration.

Each PRACH preamble maps to a PUSCH occasion and a demodulation reference signal (DMRS) port and/or a DMRS port-scrambling sequence combination according to a procedure described in one or more wireless communication standards such as in 3GPP TS <NUM>. This mapping allows a network node to uniquely determine the location of the associated PUSCH in time and frequency as well as the DMRS port and/or scrambling from the preamble selected by the wireless device.

The PRACH preambles also map to associated SSBs. The SSB to preamble association combined with the preamble to PUSCH association allow a PO to be associated with a RACH preamble. This indirect preamble to PUSCH mapping may be used to allow a network node using analog beamforming to receive a MsgA PUSCH with the same beam that the network node uses to receive the MsgA RACH preamble. <FIG> is a diagram illustrating PRACH and PUSCH slots.

Next generation wireless communication cellular systems are expected to support a wide range of use cases with varying requirements ranging from fully mobile devices to stationary internet of things (IoT) or fixed wireless broadband devices. The traffic pattern associated with some of these use cases is expected to consist of short or long bursts of data traffic with varying length of waiting period in between (here called an inactive state). In NR, both license assisted access and standalone operation in unlicensed spectrum (NR-U) (where unlicensed spectrum is also referred to as shared spectrum in this context) are to be supported in future releases of 3GPP wireless communication standard. Hence the procedure of PRACH transmission and/or scheduling request (SR) transmission in unlicensed spectrum may be investigated for future releases of 3GPP.

Network operation in an unlicensed spectrum may have to abide by one or more restrictions. One such restriction is that a device (e.g., a radio network node or a mobile terminal/wireless device) may have to monitor the shared medium, i.e., the channel, and determine that the shared medium is free (i.e., not being used by any other device(s)) before starting to transmit on the channel. This procedure is referred to as Listen-Before-Talk (LBT) or Clear Channel Assessment (CCA).

In the following, NR-U and the channel access procedure for an unlicensed channel based on LBT are described.

In order to help meet the ever-increasing data demand in wireless communication networks, NR is considered for both licensed and unlicensed spectrum. The standardization work for licensed spectrum in, for example, 3GPP Rel-<NUM> was finalized, and the study item on NR-based Access to Unlicensed Spectrum was then later finalized. The corresponding work item was approved at the 3GPP radio access network (RAN) Plenary meeting <NUM>, and compared to LTE license assisted access (LAA), NR-U may also need to support dual connectivity (DC) and standalone scenarios, where the MAC procedures including RACH and scheduling procedure on unlicensed spectrum may be subject to LBT and thus subject to potential LBT failures. In LTE LAA, there are no such issues since the RACH and scheduling related signaling can be transmitted on the primary cell (PCell) in licensed spectrum instead of unlicensed spectrum.

For discovery reference signal (DRS) transmission such as primary synchronization signal (PSS)/secondary synchronization signal (SSS), PBCH, channel state information reference signal (CSI-RS), control channel transmission such as PUCCH/PDCCH, physical data channel such as PUSCH/PDSCH, and uplink sounding reference signal (SRS) such as SRS transmission, channel sensing may be applied to determine the channel availability before the physical signal is transmitted using the channel.

The radio resource management (RRM) procedures in NR-U may be generally similar to those procedures in LTE LAA, since NR-U is aiming to reuse LAA/eLAA/feLAA technologies as much as possible to handle the coexistence between NR-U and other legacy radio access technologies (RATs). RRM measurements and report including special configuration procedure with respect the channel sensing and channel availability.

In the licensed spectrum, the wireless device measures Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of the downlink radio channel and provides the measurement reports to its serving network node (e.g., eNB/gNB). However, the measurements may not reflect the interference strength on the carrier. Another metric Received Signal Strength Indicator (RSSI) can serve such a purpose. At the network node (e.g., eNB/gNB) side, it is possible to derive RSSI based on the received RSRP and RSRQ reports, however, this derivation may require that these reports be available. Due to the LBT failure, some reports in terms of RSRP or RSRQ may be blocked where such blockage can be either due to the reference signal transmission (DRS) being blocked in the downlink or the measurement report being blocked in the uplink, for example.

The measurements in terms of RSSI may be useful. The RSSI measurements together with the time information concerning when and a time period that wireless devices have made the measurements can assist the network node (e.g., gNB/eNB) to detect a hidden node. Additionally, the network node (e.g., gNB/eNB) can measure the load situation of the carrier which is useful for the network node to prioritize some channels for load balance and channel access failure avoidance purposes.

LTE LAA may support measurements of averaged RSSI and channel occupancy for measurement reports. The channel occupancy is defined as a percentage of time that RSSI was measured above a configured threshold. For this purpose, an RSSI measurement timing configuration (RMTC) includes a measurement duration (e.g., <NUM>-<NUM>) and a period between measurements (e.g., {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>} ms).

Hence, channel access/selection for LAA was one of the aspects for co-existence with other RATs such as Wi-Fi. For instance, LAA has aimed to use carriers that are not congested with Wi-Fi.

Listen-before-talk (LBT) is designed for unlicensed spectrum co-existence with other RATs. In LBT, a radio device applies a clear channel assessment (CCA) check (i.e., channel sensing) before any transmission. The LBT procedure may use energy detection (ED) over a time period (a 'sensing slot') compared to a certain energy detection threshold (ED threshold) in order to determine if a channel is idle. In case the channel is determined to be occupied, the transmitter (e.g., wireless device, network node) performs a random back-off within a contention window before next CCA attempt. In order to protect the acknowledgement (ACK) transmissions, the transmitter (e.g., wireless device, network node) may defer a period after each busy CCA slot prior to resuming back-off. As soon as the transmitter (e.g., wireless device, network node) has grasped access to a channel, the transmitter (e.g., wireless device, network node) may only be allowed to perform transmission up to a maximum time duration (namely, the maximum channel occupancy time (MCOT)). For quality of service (QoS) differentiation, a channel access priority based on the service type has been defined. For example, four LBT priority classes are defined for differentiation of channel access priorities between services using different contention window sizes (CWS) and MCOT durations.

As described above and in, for example, 3GPP TR <NUM>, Listen-Before-Talk (LBT) is designed for unlicensed spectrum co-existence with other RATs and other wireless devices of the system and the medium. Under this mechanism, a radio device such as a wireless device applies a Clear Channel Assessment (CCA) check before any transmission. The transmitter (e.g., wireless device, network node) uses energy detection (ED) over a time period compared to a certain threshold (ED threshold) to determine if a channel is idle. Another CCA mechanism is to detect a known preamble.

In cases where the channel is determined to be occupied based on the CCA check, the transmitter (e.g., wireless device, network node) device performs a random back-off within a contention window before next CCA attempt.

To protect the ACK transmissions, the transmitter may defer a period after each busy CCA slot prior to resuming back-off. As soon as the transmitter (e.g., wireless device, network node) has grasped the channel, the transmitter (e.g., wireless device, network node) may only be allowed to perform transmission up to a maximum time duration called the Maximum Channel Occupancy time (MCOT). MCOT is configured per channel access priority class (p). For example, in wireless communication standards such as 3GPP TS <NUM> specifies the MCOT (Tulm,cot,p) for UL transmission is specified as follows.

For QoS differentiation, a channel access priority scheme based on the service type has been defined. For example, in LTE-LAA four CCA/LBT Channel Access Priority Classes (CAPCs) are defined for differentiation of contention window sizes (CWS) and MCOT between services. In LTE-LAA, the following mapping between CAPC and QCIs is defined in, for example, 3GPP TS <NUM>:.

Therefore, when scheduling UL/DL traffic, the network node may consider the QCI of the traffic to be transmitted. For uplink, the CAPC that the wireless devices needs to use for a given UL transmission is either signaled in the UL grant on the PDCCH for dynamic scheduling or indicated as part of a logical channel configuration for autonomous LTE-LAA UL transmissions. In the latter case, the wireless device may apply the CAPC indicated in the logical channel configuration when autonomously transmitting data from that logical channel. In case there are multiple MAC service data units (SDUs) multiplexed in the same MAC protocol data unit (PDU) and associated with different logical channels, the wireless device may apply the QCI associated with the lowest CAPC of all the logical channels included in the MAC PDU.

The channel access schemes for NR-based access for unlicensed spectrum can be classified into the following categories, for example:.

However, the use of <NUM>-step RACH and LBT in existing systems is not without issues. For example, the wireless device may need to perform UL LBT two times for <NUM>-step RACH MsgA transmission: once before PRACH transmission and the other time before PUSCH if the time gap between resources for PRACH and PUSCH is large. More UL LBT attempts may decrease the probability to be successful in MsgA transmission in <NUM>-step RACH. In other words, the existing solution for <NUM>-step RACH may lead to higher probability of failure of MsgA transmission and therefore decreases the likelihood of using <NUM>-step RACH on a carrier of shared spectrum, e.g., which is subject to LBT for transmission such as a carrier of unlicensed spectrum.

Further, when the network node configures both <NUM>-step RACH and <NUM>-step RACH for a wireless device, it is not defined which procedure, i.e., <NUM>-step or <NUM>-step RACH, the wireless device should use.

Prior art examples are: <CIT>; <CIT>; and <NPL>".

The scope of the present invention is defined in the appended independent claims. Specific embodiments of the present invention are defined in the dependent claims. In the followings some parts of the description, that are not covered by the claims, are considered background information that is useful for understanding the present invention.

The present invention is directed to a wireless device (claim <NUM>), a method performed by said wireless device (independent claim <NUM>) and a corresponding network node (independent claim <NUM>) for adapting a timing gap for a random access procedure and/or selecting a random access procedure type to implement.

According to one or more embodiments, the network node adapts the time gap (Tg) between resources used for PRACH and PUSCH transmissions in MsgA on a carrier for <NUM>-step RACH based at least on whether the carrier is subject to LBT. The adaptation of the time gap on a carrier subject to LBT depends on one or more parameters related to LBT operation, e.g., channel occupancy time (COT), LBT failure statistics, etc. For example:.

According one or more embodiments performed at the wireless device, the wireless device is configured by the network node with a rule indicating what gap to use for the transmission of PRACH and PUSCH in MsgA. The rule specifies the value of Tg, which depends on COT, UL LBT failures, as mentioned above. In one example, the wireless device autonomously determines Tg value from a set of possible values based on COT, UL LBT failures and performs the random access accordingly. The wireless device can also be pre-defined by the network node to use a certain Tg based on the criteria.

According to another embodiment, when the network node may configure <NUM> RA types, i.e., <NUM>-step RACH and <NUM>-step RACH, then the wireless device may select the RA type depending on or at least based on <NUM>) the configured time gap (tg) between PRACH and PUSCH transmissions in <NUM>-step RACH MsgA, and/or <NUM>) a relation between the number of UL LBT failures for random access procedures and a threshold. The wireless device may use the selected type of the RA for performing random access in a cell operating on a carrier subject to LBT.

Some NR-U wireless device implementations may require a delay between PRACH and PUSCH. This delay increases the amount of time needed to transmit the PRACH and PUSCH, and so a larger COT may be needed for such wireless devices. Therefore, in another embodiment, a wireless device adapts a random access procedure according to a channel occupancy time. The wireless device may determine a channel occupancy time for a transmission by the wireless device using shared channel access. When the combined duration of the random access preamble, the PO, and a minimum delay is not greater than the channel occupancy time, the wireless device may transmit the PRACH and a PUSCH in the PO such that the random access preamble is followed by the PUSCH at a delay not less than the minimum delay, wherein the combined duration comprises the time from the start of the preamble to the end of the PO. When the combined duration of a PRACH, the PO, and the minimum delay for a wireless device is greater than the channel occupancy time, the wireless device may transmit the random access preamble in the RO. In some such embodiments, the minimum preamble-RO delay is a wireless device capability. In these embodiments, the wireless device may be identified as supporting transmission of the random access preamble followed by a PUSCH at a delay not less than the minimum delay.

Therefore, one or more embodiments of the disclosure advantageously provides for one or more of:.

According to one aspect of the disclosure, a wireless device is provided. The wireless device includes processing circuitry configured to select one of a plurality of random access procedure types based on at least one of a quantity of clear channel assessment, CCA, failures associated with random access attempts and a time gap between a physical random access channel, PRACH, resources and physical uplink shared channel, PUSCH, resources. The processing circuitry is further configured to perform a random access procedure one of based on and using the selected one of the plurality of random access procedure types.

According to one or more embodiments of this aspect, the quantity of CCA failures associated with random access attempts is a property associated with message A of a two step random access procedure type. According to one or more embodiments of this aspect, the quantity of CCA failures associated with random access attempts is a property associated with message <NUM> of a four step random access procedure type. According to one or more embodiments of this aspect, the processing circuitry is further configured to detect a CCA failure and increment the quantity of CCA failures associated with the random access attempts by a predefined amount.

According to one or more embodiments of this aspect, the processing circuitry is further configured to receive an indication of a predefined quantity threshold, and trigger the selection of one of the plurality of random access procedure types based at least on the quantity of CCA failures exceeding the predefined quantity threshold. According to one or more embodiments of this aspect, each of the CCA failures corresponds to a listen before talk, LBT, failure. According to one or more embodiments of this aspect, the processing circuitry is further configured to receive an indication of a predefined time gap threshold, and trigger the selection of one of the plurality of random access procedure types based at least on the time gap between the PRACH resources and PUSCH resources exceeding the predefined time gap threshold.

According to one or more embodiments of this aspect, the time gap is configured based at least on a channel occupancy time. According to one or more embodiments of this aspect, the processing circuitry is configured to receive an indication of a plurality of time gaps between PRACH resources and PUSCH resources, and select one of the plurality of time gaps to implement based at least on the quantity of CCA failures. According to one or more embodiments of this aspect, the plurality of random access procedure types includes a two step random access procedure type and a four step random access procedure type. According to another aspect of the disclosure, a network node configured to communicate with a wireless device is provided. The network node includes processing circuitry configured to configure the wireless device with at least one of a predefined quantity threshold for comparison with a quantity of clear channel assessment, CCA, failures, and a predefined time gap threshold for comparison with a time gap between physical random access channel, PRACH, resources and physical uplink shared channel, PUSCH, resources. The processing circuitry is further configured to receive random access procedure signaling of one of a plurality of random access procedures types based on at least one of the predefined quantity threshold and predefined time gap threshold being exceeded.

According to one or more embodiments of this aspect, the quantity of CCA failures associated with random access attempts is a property associated with message A of a two step random access procedure type. According to one or more embodiments of this aspect, the quantity of CCA failures associated with random access attempts is a property associated with message <NUM> of a four step random access procedure type. According to one or more embodiments of this aspect, each of the CCA failures corresponds to a listen before talk, LBT, failure.

According to one or more embodiments of this aspect, the time gap is configured based at least on a channel occupancy time. According to one or more embodiments of this aspect, the processing circuitry is configured to transmit an indication of a plurality of time gaps between PRACH resources and PUSCH resources for selection by the wireless device based at least on the quantity of CCA failures. According to one or more embodiments of this aspect, the plurality of random access procedure types includes a two step random access procedure type and a four step random access procedure type.

According to another aspect of the disclosure, a method implemented by a wireless device is provided. One of a plurality of random access procedure types is selected based on at least one of a quantity of clear channel assessment, CCA, failures associated with random access attempts, and a time gap between a physical random access channel, PRACH, resources and physical uplink shared channel, PUSCH, resources. A random access procedure is performed one of based on and using the selected one of the plurality of random access procedure types is implemented.

According to one or more embodiments of this aspect, the quantity of CCA failures associated with random access attempts is a property associated with message A of a two step random access procedure type. According to one or more embodiments of this aspect, the quantity of CCA failures associated with random access attempts is a property associated with message <NUM> of a four step random access procedure type. According to one or more embodiments of this aspect, a CCA failure is detected and the quantity of CCA failures associated with the random access attempts is incremented by a predefined amount.

According to one or more embodiments of this aspect, an indication of a predefined quantity threshold is received. The selection of one of the plurality of random access procedure types is triggered based at least on the quantity of CCA failures exceeding the predefined quantity threshold. According to one or more embodiments of this aspect, each of the CCA failures corresponds to a listen before talk, LBT, failure. According to one or more embodiments of this aspect, an indication of a predefined time gap threshold is received. The selection of one of the plurality of random access procedure types is triggered based at least on the time gap between the PRACH resources and PUSCH resources exceeding the predefined time gap threshold.

According to one or more embodiments of this aspect, the time gap is configured based at least on a channel occupancy time. According to one or more embodiments of this aspect, an indication of a plurality of time gaps between PRACH resources and PUSCH resources is received. One of the plurality of time gaps to implement is selected based at least on the quantity of CCA failures. According to one or more embodiments of this aspect, the plurality of random access procedure types includes a two step random access procedure type and a four step random access procedure type.

According to another aspect of the disclosure, a method implemented by a network node that is configured to communicate with a wireless device is provided. The wireless device is configured with at least one of a predefined quantity threshold for comparison with a quantity of clear channel assessment, CCA, failures, and a predefined time gap threshold for comparison with a time gap between physical random access channel, PRACH, resources and physical uplink shared channel, PUSCH, resources. Random access procedure signaling of one of a plurality of random access procedures types is received based on at least one of the predefined quantity threshold and predefined time gap threshold being exceeded.

According to one or more embodiments of this aspect, the time gap is configured based at least on a channel occupancy time. According to one or more embodiments of this aspect, an indication is transmitted of a plurality of time gaps between PRACH resources and PUSCH resources for selection by the wireless device based at least on the quantity of CCA failures. According to one or more embodiments of this aspect, the plurality of random access procedure types includes a two step random access procedure type and a four step random access procedure type.

Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to adapting a timing gap for a random access procedure and/or selecting a random access procedure type to implement. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

The term "network node" used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi-standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), network controller, central unit (e.g. in a gNB), distributed unit (e.g., in a gNB), baseband unit, centralized baseband, C-RAN, integrated access and backhaul (IAB) node, relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (e.g., MME, MSC, etc.), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), O&M, OSS, SON, positioning node (e.g., E-SMLC), etc. The network node may also comprise test equipment. The term "radio node" used herein may be used to also denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

The WD herein can be another type of node and/or any type of wireless device capable of communicating with a network node or another WD over radio signals, such as wireless device (WD). The WD may also be a radio communication device, target device, device to device (D2D) WD, machine type WD or WD capable of machine to machine communication (M2M), low-cost and/or low-complexity WD, a sensor equipped with WD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device, etc..

Also, in some embodiments, the generic term "radio network node" is used.

The term radio access technology, or RAT, may refer to any RAT, e.g., UTRA, E-UTRA, narrow band internet of things (NB-IoT), WiFi, Bluetooth, next generation RAT, New Radio (NR), <NUM>, <NUM>, etc. Any of the equipment denoted by the terms node, wireless device, network node or radio network node may be capable of supporting a single or multiple RATs.

The term signal used herein can be any physical signal or physical channel. Examples of physical signals are reference signal such as PSS, SSS, CSI-RS, DMRS, signals in SSB, CRS, PRS, SRS, etc. The term physical channel used herein is also called as 'channel', which contains higher layer information. Examples of physical channels are MIB, PBCH, NPBCH, PDCCH, PDSCH, sPUCCH, sPDSCH, sPUSCH, MPDCCH, NPDCCH, NPDSCH, E-PDCCH, PUSCH, PUCCH, NPUSCH, etc..

The term time resource used herein may correspond to any type of physical resource or radio resource expressed in terms of length of time. Examples of time resources are: symbol, time slot, subframe, radio frame, TTI, interleaving time, etc. The term TTI used herein may correspond to any time period (T0) over which a physical channel can be encoded and optionally interleaved for transmission. The physical channel is decoded by the receiver over the same time period (T0) over which it was encoded. The TTI may also interchangeably called as short TTI (sTTI), transmission time, slot, sub-slot, mini-slot, mini-subframe, etc..

The term time-frequency resource used herein for any radio resource is defined in any time-frequency resource grid in a cell. Examples of time-frequency resource are resource block, subcarrier, resource block (RB) etc. The RB may also be interchangeably called as physical RB (PRB), virtual RB (VRB), etc..

The term "quantity" may be used interchangeably with "number" in one or more embodiments. For example, a quantity of CCA failures may correspond to a number of CCA failures.

The term listen-before-talk (LBT) as used herein may correspond to DL LBT, UL LBT, or both. LBT is also interchangeably and more generally called as clear channel assessment (CCA), carrier sense multiple access (CSMA) procedure, channel assessment scheme, shared spectrum channel access etc. The CCA based operation is more generally called contention-based operation. The transmission of signals on a carrier subjected to CCA is also called contention-based transmission. The contention-based operation is typically used for transmission on carriers of unlicensed frequency band. But this mechanism may also be applied for operating on carriers belonging to licensed band for example to reduce interference. The transmission of signals on a carrier which is not subjected to CCA is also called contention free transmission. As used herein, a CCA failure may correspond to sensing a channel is not clear during the CCA or detecting energy above a threshold during the CCA. As used herein, a random access attempt may correspond to initiating a random access procedure and performing CCA before determining whether to transmit random access signaling associated with the random access procedure. The random access attempt may fail if CCA fails.

An indication generally may explicitly and/or implicitly indicate the information it represents and/or indicates. Implicit indication may for example be based on position and/or resource used for transmission. Explicit indication may for example be based on a parametrization with one or more parameters, and/or one or more index or indices, and/or one or more bit patterns representing the information.

A cell may be generally a communication cell, e.g., of a cellular or mobile communication network, provided by a node. A serving cell may be a cell on or via which a network node (the node providing or associated to the cell, e.g., base station, gNB or eNodeB) transmits and/or may transmit data (which may be data other than broadcast data) to a user equipment, in particular control and/or user or payload data, and/or via or on which a user equipment transmits and/or may transmit data to the node; a serving cell may be a cell for or on which the user equipment is configured and/or to which it is synchronized and/or has performed an access procedure, e.g., a random access procedure, and/or in relation to which it is in a RRC_connected or RRC_idle state, e.g., in case the node and/or user equipment and/or network follow the LTE-standard. One or more carriers (e.g., uplink and/or downlink carrier/s and/or a carrier for both uplink and downlink) may be associated to a cell.

Transmitting in downlink may pertain to transmission from the network or network node to the wireless device. Transmitting in uplink may pertain to transmission from the wireless device to the network or network node. Transmitting in sidelink may pertain to (direct) transmission from one wireless device to another. Uplink, downlink and sidelink (e.g., sidelink transmission and reception) may be considered communication directions. In some variants, uplink and downlink may also be used to described wireless communication between network nodes, e.g. for wireless backhaul and/or relay communication and/or (wireless) network communication for example between base stations or similar network nodes, in particular communication terminating at such. It may be considered that backhaul and/or relay communication and/or network communication is implemented as a form of sidelink or uplink communication or similar thereto.

Configuring a terminal or wireless device or node may involve instructing and/or causing the wireless device or node to change its configuration, e.g., at least one setting and/or register entry and/or random access procedure configurations. A terminal or wireless device or node may be adapted to configure itself, e.g., according to information or data in a memory of the terminal or wireless device. Configuring a node or terminal or wireless device by another device or node or a network may refer to and/or comprise transmitting information and/or data and/or instructions to the wireless device or node by the other device or node or the network, e.g., allocation data (which may also be and/or comprise configuration data) and/or scheduling data and/or scheduling grants. Configuring a terminal may include sending allocation/configuration data to the terminal indicating which modulation and/or encoding to use. A terminal may be configured with and/or for scheduling data and/or to use, e.g., for transmission, scheduled and/or allocated uplink resources, and/or, e.g., for reception, scheduled and/or allocated downlink resources. Uplink resources and/or downlink resources may be scheduled and/or provided with allocation or configuration data.

A licensed band or spectrum may be a part of the frequency spectrum that is and/or has to be licensed for use, e.g. by a telecommunications operator. An unlicensed band or spectrum may be a part of the frequency spectrum that is available without such license. WLAN/WiFi usually uses such unlicensed bands. The requirements for using licensed bands are usually quite different from unlicensed bands, e.g. due to licensed bands being controlled by one operator, whereas unlicensed bands usually are not subject to a centralized operator. Thus, LBT procedures are usually required for unlicensed bands, which may be adapted to facilitate fair distribution of access to the unlicensed spectrum.

Embodiments may provide for adapting a timing gap for a random access procedure and/or selecting a random access procedure type to implement. Referring again to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in <FIG> a schematic diagram of a communication system <NUM>, according to an embodiment, such as a 3GPP-type cellular network that may support standards such as LTE and/or NR (<NUM>), which comprises an access network <NUM>, such as a radio access network, and a core network <NUM>. The access network <NUM> comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes <NUM>), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas <NUM>). Each network node 16a, 16b, 16c is connectable to the core network <NUM> over a wired or wireless connection <NUM>. A first wireless device (WD) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of WDs 22a, 22b (collectively referred to as wireless devices <NUM>) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole WD is in the coverage area or where a sole WD is connecting to the corresponding network node <NUM>. Note that although only two WDs <NUM> and three network nodes <NUM> are shown for convenience, the communication system may include many more WDs <NUM> and network nodes <NUM>.

In some embodiments, the intermediate network <NUM> may comprise two or more sub-networks (not shown) and may communicate with access network <NUM> via communication link <NUM>.

The communication system of <FIG> as a whole enables connectivity between one of the connected WDs 22a, 22b and the network node <NUM>. A network node <NUM> is configured to include a random access channel (RACH) unit <NUM> which is configured to perform one or more network node <NUM> functions as described herein such as with respect to adapting a timing gap for a random access procedure and/or selecting a random access procedure type to implement. A wireless device <NUM> is configured to include a random access (RA) unit <NUM> which is configured to perform one or more wireless device <NUM> function as described herein such as with respect to adapting a timing gap for a random access procedure and/or selecting a random access procedure type to implement.

Example implementations, in accordance with an embodiment, of the WD <NUM> and network node <NUM> discussed in the preceding paragraphs will now be described with reference to <FIG>.

The communication system <NUM> includes a network node <NUM> provided in a communication system <NUM> and including hardware <NUM> enabling it to communicate with other network nodes <NUM> and with the WD <NUM>. The communication interface <NUM> may be configured to facilitate a connection <NUM> to other network nodes <NUM>, for example.

Thus, the network node <NUM> further has software <NUM> stored internally in, for example, memory <NUM>, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node <NUM> via an external connection. The processing circuitry <NUM> may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by network node <NUM>. Processor <NUM> corresponds to one or more processors <NUM> for performing network node <NUM> functions described herein. The memory <NUM> is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software <NUM> may include instructions that, when executed by the processor <NUM> and/or processing circuitry <NUM>, causes the processor <NUM> and/or processing circuitry <NUM> to perform the processes described herein with respect to network node <NUM>. For example, processing circuitry <NUM> of the network node <NUM> may include RACH unit <NUM> that is configured to perform one or more network node <NUM> function as described herein such as with respect to adapting a timing gap for a random access procedure and/or selecting/configurating a random access procedure type to implement.

The client application <NUM> may be operable to provide a service to a human or non-human user via the WD <NUM>.

The processing circuitry <NUM> may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by WD <NUM>. The processor <NUM> corresponds to one or more processors <NUM> for performing WD <NUM> functions described herein. The WD <NUM> includes memory <NUM> that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software <NUM> and/or the client application <NUM> may include instructions that, when executed by the processor <NUM> and/or processing circuitry <NUM>, causes the processor <NUM> and/or processing circuitry <NUM> to perform the processes described herein with respect to WD <NUM>. For example, the processing circuitry <NUM> of the wireless device <NUM> may include a RA unit <NUM> configured to perform one or more wireless device <NUM> functions described herein such as with respect to adapting a timing gap for a random access procedure and/or selecting a random access procedure type to implement.

In some embodiments, the inner workings of the network node <NUM> and WD <NUM> may be as shown in <FIG> and independently, the surrounding network topology may be that of <FIG>. Although <FIG> and <FIG> show various "units" such as RACH unit <NUM> and RA unit <NUM> as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

<FIG> is a flowchart of an exemplary process in a network node <NUM> according to some embodiments of the present disclosure. One or more Blocks and/or functions performed by network node <NUM> may be performed by one or more elements of network node <NUM> such as by RACH unit <NUM> in processing circuitry <NUM>, processor <NUM>, radio interface <NUM>, etc. In one or more embodiments, network node <NUM> such as via one or more of processing circuitry <NUM>, processor <NUM>, RACH unit <NUM>, communication interface <NUM> and radio interface <NUM> is configured to configure (Block S100) the wireless device with a time gap associated with a random access procedure where the time gap value is based at least on whether a carrier is subject to a listen-before-talk, LBT, procedure, as described herein. In one or more embodiments, network node <NUM> such as via one or more of processing circuitry <NUM>, processor <NUM>, RACH unit <NUM>, communication interface <NUM> and radio interface <NUM> is configured to optionally perform (Block S102) a random access procedure based at least in part on the time gap, as described herein.

According to one or more embodiments, the time gap is between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH. According to one or more embodiments, the time gap is further based on at least one parameter of the LBT procedure. According to one or more embodiments, the at least one parameter is based at least on one of a channel occupancy time, COT, LBT failure statistics and whether the COT is configured for an unlicensed carrier.

According to one or more embodiments, the processing circuitry <NUM> is configured to configure the wireless device <NUM> with <NUM>-step RACH and the <NUM>-step RACH. According to one or more embodiments, the processing circuitry <NUM> is further configured to configure with wireless device <NUM> with additional time gaps between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH for selection by the wireless device <NUM>.

<FIG> is a flowchart of an exemplary process in a network node <NUM> according to some embodiments of the present disclosure. One or more Blocks and/or functions performed by network node <NUM> may be performed by one or more elements of network node <NUM> such as by RACH unit <NUM> in processing circuitry <NUM>, processor <NUM>, radio interface <NUM>, etc. In one or more embodiments, network node <NUM> is configured to configure (Block S104) the wireless device <NUM> with at least one of: a predefined quantity threshold for comparison with a quantity of clear channel assessment, CCA, failures, and a predefined time gap threshold for comparison with a time gap between physical random access channel, PRACH, resources and physical uplink shared channel, PUSCH, resources, as described herein. The network node <NUM> is configured to receive (Block S106) random access procedure signaling of one of a plurality of random access procedures types based on at least one of the predefined quantity threshold and predefined time gap threshold being exceeded, as described herein.

According to one or more embodiments, the quantity of CCA failures associated with random access attempts is a property associated with message A of a two step random access procedure type, as described herein. According to one or more embodiments, the quantity of CCA failures associated with random access attempts is a property associated with message <NUM> of a four step random access procedure type, as described herein. According to one or more embodiments, each of the CCA failures corresponds to a listen before talk, LBT, failure, as described herein.

According to one or more embodiments, the time gap is configured based at least on a channel occupancy time, as described herein. According to one or more embodiments, the processing circuitry <NUM> is configured to transmit an indication of a plurality of time gaps between PRACH resources and PUSCH resources for selection by the wireless device <NUM> based at least on the quantity of CCA failures. According to one or more embodiments, the plurality of random access procedure types includes a two step random access procedure type and a four step random access procedure type.

<FIG> is a flowchart of an exemplary process in a wireless device <NUM> according to some embodiments of the present disclosure. One or more Blocks and/or functions performed by wireless device <NUM> may be performed by one or more elements of wireless device <NUM> such as by RA unit <NUM> in processing circuitry <NUM>, processor <NUM>, radio interface <NUM>, etc. In one or more embodiments, wireless device such as via one or more of processing circuitry <NUM>, processor <NUM>, RA unit <NUM> and radio interface <NUM> is configured to receive (Block S108) a configuration for a time gap associated with a random access procedure where the time gap value is based at least on whether a carrier is subject to a listen-before-talk, LBT, procedure, as described herein. In one or more embodiments, wireless device <NUM> such as via one or more of processing circuitry <NUM>, processor <NUM>, RA unit <NUM> and radio interface <NUM> is configured to optionally perform (Block S110) a random access procedure based at least in part on the time gap, as described herein.

According to one or more embodiments, the time gap is between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH. According to one or more embodiments, the time gap is further based on at least one parameter of the LBT procedure. According to one or more embodiments, the at least one parameter is based at least on one of a channel occupancy time, COT, LBT failure statistics and whether the COT is configured for an unlicensed carrier. According to one or more embodiments, the processing circuitry <NUM> is further configured to receive a configuration for <NUM>-step RACH and the <NUM>-step RACH, and one of select and switch between the <NUM>-step RACH and the <NUM>-step RACH based at least in part on the at least one parameter. According to one or more embodiments, the processing circuitry <NUM> is further configured to receive configurations for additional time gaps between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH, and select among the time gaps for implementation for the random access procedure.

<FIG> is a flowchart of another example process in a wireless device <NUM> according to some embodiments of the present disclosure. One or more Blocks and/or functions performed by wireless device <NUM> may be performed by one or more elements of wireless device <NUM> such as by RA unit <NUM> in processing circuitry <NUM>, processor <NUM>, radio interface <NUM>, etc. In one or more embodiments, wireless device <NUM> is configured to select (Block S112) one of a plurality of random access procedure types based on at least one of: a quantity of clear channel assessment, CCA, failures associated with random access attempts, and a time gap between a physical random access channel, PRACH, resources and physical uplink shared channel, PUSCH, resources, as described herein. The wireless device <NUM> is further configured to perform (Block S114) a random access procedure one of based on and using the selected one of the plurality of random access procedure types.

According to one or more embodiments, the quantity of CCA failures associated with random access attempts is a property associated with message A of a two step random access procedure type, as described herein. According to one or more embodiments, the quantity of CCA failures associated with random access attempts is a property associated with message <NUM> of a four step random access procedure type, as described herein. According to one or more embodiments, the processing circuitry <NUM> is further configured to detect a CCA failure and increment the quantity of CCA failures associated with the random access attempts by a predefined amount, as described herein.

According to one or more embodiments, the processing circuitry <NUM> is further configured to: receive an indication of a predefined quantity threshold, and trigger the selection of one of the plurality of random access procedure types based at least on the quantity of CCA failures exceeding the predefined quantity threshold, as described herein. According to one or more embodiments, each of the CCA failures corresponds to a listen before talk, LBT, failure. According to one or more embodiments, the processing circuitry <NUM> is further configured to: receive an indication of a predefined time gap threshold, and trigger the selection of one of the plurality of random access procedure types based at least on the time gap between the PRACH resources and PUSCH resources exceeding the predefined time gap threshold, as described herein.

According to one or more embodiments, the time gap is configured based at least on a channel occupancy time. According to one or more embodiments, the processing circuitry <NUM> is configured to: receive an indication of a plurality of time gaps between PRACH resources and PUSCH resources, and select one of the plurality of time gaps to implement based at least on the quantity of CCA failures. According to one or more embodiments, the plurality of random access procedure types includes a two step random access procedure type and a four step random access procedure type.

Having generally described arrangements for adapting a timing gap for a random access procedure and/or selecting a random access procedure type to implement, details for these arrangements, functions and processes are provided as follows, and which may be implemented by the network node <NUM> and/or wireless device <NUM>.

Embodiments provide adapting a timing gap for a random access procedure and/or selecting a random access procedure type to implement. One or more network node <NUM> functions described below may be performed by one or more of processing circuitry <NUM>, processor <NUM>, radio interface <NUM>, RACH unit <NUM>, etc. One or more wireless device <NUM> functions described below may be performed by one or more of processing circuitry <NUM>, processor <NUM>, radio interface <NUM>, RA unit <NUM>, etc..

The scenario comprises a wireless device <NUM> intending to transmit random access to a first cell (cell1), which in turn is managed or served or operated by a first network node <NUM> (NN1). The wireless device <NUM> may or may not be served by cell1. In one example, cell1 is a target cell of the wireless device <NUM>, e.g., for performing RA at cell change procedure, at cell selection, etc. Examples of cell change procedures are cell re-selection, RRC re-establishment, handover, random access, etc..

In another example, cell1 is also a serving cell of the wireless device <NUM>, e.g., for performing RA for beam recovery, etc. In yet another example, cell1 is the serving cell of the wireless device <NUM>, e.g., when performing random access as part of the RRC re-establishment upon radio link failure (RLF) declaration and expiry of T310 timer where a T310 is a predefined timer known in the art. Cell1 is being operated on a carrier belonging to a spectrum whose access may require the radio node (e.g., wireless device <NUM>, network node <NUM>) to apply a CCA operation, e.g., LBT. In one example, the spectrum is a shared spectrum. An example of the shared spectrum is a carrier of an unlicensed band or spectrum. The wireless device <NUM> may be required to perform UL LBT before the channel access and the first network node <NUM> (NN1) may be required to perform DL LBT before the channel access on unlicensed band.

The wireless device <NUM> is configured to use <NUM>-step RACH (i.e., <NUM>-step RA type or Type-<NUM> random access procedure) and <NUM>-step RACH (i.e., <NUM>-step RA type or Type-<NUM> random access procedure) for the random access procedure.

The network node <NUM> configures the maximum channel occupancy time (COT or MCOT) for shared channel access operation. COT and MCOT are interchangeably used herein. The value of COT may depend on local regulation in a region, e.g., is based at least on the deployed country or region. Alternatively, the wireless device <NUM> obtains information about the COT/MCOT based on, e.g., channel access schemes type, LBT type.

The random access procedure may be required, for example, when the wireless device <NUM> accesses the cell for performing one or more procedures related to cell change. Examples of such procedures are cell selection, cell reselection, handover, RRC re-establishment, or RRC connection release with redirection, configuration or change of special cell (SpCell) in multi-connectivity (e.g., addition of PSCell, PSCell change etc.). In another example, the random access may be required to indicate a beam recovery procedure, scheduling request (SR). In yet another example, the random access may be required to assist the NN1 (e.g., serving network node <NUM>) to estimate the propagation delay between the wireless device <NUM> and the NN1. This in turn is used for adapting the timing advance command for the wireless device <NUM>.

In one embodiment, the network node <NUM> (NN) adapts a time gap (Tg) between time resources for PRACH and PUSCH transmission in MsgA for <NUM>-step RACH based on whether the carrier is subject to LBT or not, based on LBT type.

For example, the network node <NUM> configures Tg depending on the COT configured for operated unlicensed carrier. For example, the network node <NUM> selects Tg so that the total transmission time of MsgA does not exceed COT. Consider one slot length is <NUM>, e.g., for subcarrier spacing (SCS) of <NUM>. If PRACH transmission period is <NUM>, and PUSCH transmission period is <NUM>, and COT=<NUM>, the network node <NUM> sets the time gap up to <NUM>, which corresponds to <NUM> slots with SCS=<NUM>. <FIG> illustrates this configuration as an example.

In one or more embodiments, the relation between Tg and COT can be determined by a rule. The rule can be pre-defined or the wireless device <NUM> can be configured by the network node <NUM>, e.g., by sending a message to the wireless device <NUM>. In the former case as an example, the wireless device <NUM> upon determining the COT may also determine Tg. In yet another example, even if the relation between Tg and COT is pre-defined (e.g., by a rule) the network node <NUM> may still be able to adapt the value of Tg, e.g., to a value smaller than the pre-defined Tg. In one or more embodiments, the network node <NUM> may adapt the time gap (Tg) based on information related to CCA operational result or the outcome of the CCA operations performed in a network node <NUM>, e.g., in the serving base station of the wireless device, prior to an attempt to transmit a DL signal or message. For example, the CCA operations are performed by the network node <NUM> prior to transmitting signals in the downlink. The CCA operational results may include results of CCA failure or CCA success. The CCA operational results can be obtained by the network node <NUM> over a certain time period (T0). In this case, the wireless device <NUM> adapts the Tg based on CCA operational results. In one example, if CCA operational results indicate a high failure rate, then Tg is set to a larger value compared to the case when CCA operational results indicate low failure rate. By setting a large gap, the probability of LBT success increases, meaning that the wireless device <NUM> is more likely to succeed with the transmissions contained in MsgA. In a similar way, if the CCA operational results indicate low failure rate (i.e., failure rate below a threhsold), then the network node <NUM> may select a smaller gap, preferably within the COT. This may reduce the number of CCA evaluations in the wireless device <NUM> as the transmission may take place within the COT or close to each other. Another advantage is that MsgA is transmitted faster.

In one or more embodiments, the wireless device <NUM> may select a gap based on the received CCA operational results, which can be, e.g., broadcast in system information. In one example, the selection of Tg is be based on CCA operational results sent out in information element (IE) "AvailableRB-SetPerCell" or the like which indicates the availability of RBs of a serving cell operating in a carrier subject to CCA. As used herein in one or more embodiments, CCA operational results include or correspond to CCA failures that may correspond to LBT failures.

In one or more embodiments, the network node <NUM> configures the wireless device <NUM> with one or more values for one or more time gaps, and the wireless device <NUM> selects the time gap based on one or more of the UL LBT status, CCA operational results (as described above) received from other nodes such as other network nodes <NUM>. For example, the wireless device <NUM> may receive information about the CCA operational results that may include results of CCA failure or CCA success from the serving network node <NUM> and this information can be used for selecting one of multiple time gaps.

For example, the network node <NUM> configures M MsgA configurations and each configuration has different time gap length, e.g., (Tg1, Tg2,. , TgM), where Tg1 < Tg2 <. Moreover, the network node <NUM> configures thresholds (H1, H2,. , HM-<NUM>), where H1 < H2 <. < HM-<NUM>, to enable the wireless device <NUM> to choose a particular value of Tg. N indicates the number or rate of LBT failures where one or more configured thresholds may be compared to N as shown in the example of Table <NUM>. The network node <NUM> can store such a set of MsgA configurations in a form of table as shown in Table <NUM>, below, for example. The network node <NUM> can signal such a table to the wireless device <NUM>, e.g., via RRC signaling. In another example, this configuration set can be pre-defined or updated adaptively during the operation. In this case, selection of time gap is conditioned on the H value as shown in Table <NUM>.

Each value of Tg is further associated with a set of PRACH and PUSCH transmission resources in MsgA, e.g., time slots and PRBs within the slot. The network node <NUM> also configures a set of PRACH and PUSCH transmission resources in MsgA (e.g., time-frequency resources such as slots and PRBs for PRACH and PUSCH transmissions) for each configuration used by the network node <NUM>.

When N indicates the number (i.e., quantity) of UL LBT failures, for example, when the wireless device <NUM> starts the random access procedure with <NUM>-step RACH, the wireless device <NUM> sets N=<NUM> and transmit MsgA with Tg=Tg1 as illustrated in <FIG>. If the wireless device <NUM> fails MsgA transmission due to the UL LBT failure, N is increased by <NUM>. After several consecutive RACH transmission failures and N becomes equal to H1, then the wireless device <NUM> transmits MsgA with Tg=Tg2 as illustrated in <FIG>. In general, if N ≥ Hm, then the wireless device <NUM> transmits MsgA based on configuration m, which corresponds to Tg=Tgm. In this example, the quantity of CCA failures is a property associated with message A of a <NUM>-step RACH (i.e., random access procedure type).

In one or more embodiments, the network node <NUM> may use two configurations configuration <NUM> and configuration <NUM> in cell1, i.e., with one threshold (H1). If the UL LBT failures experienced by the wireless device <NUM> remain below H1 (i.e., N < H1) then the wireless device <NUM> selects Tg = Tg1 and determines associated resources where PRACH and PUSCH in MsgA can be transmitted and transmits PRACH and PUSCH in the determined resources. If the UL LBT failures experienced by the wireless device <NUM> becomes equal to or larger than H1 (i.e., N ≥ H1) then the wireless device <NUM> selects Tg = Tg2 and determines the associated resources where PRACH and PUSCH in MsgA can be transmitted and then transmits PRACH and PUSCH in the determined resources.

In one or more examples, the network node <NUM> configuring the wireless device <NUM> with information (e.g., parameters Tg, etc.) may be the same as the first network node <NUM> (NN1) or it may be another network node <NUM> (e.g., NN2) different than the first network node <NUM>.

In one or more embodiments, the wireless device <NUM> adapts type of RA depending on the time gap between PRACH and PUSCH time resources and/or number of UL LBT failures experienced by the wireless device <NUM>. In one example, the adaptation of the RA type is based on information received from the network and/or network node <NUM> which is in turn based on the CCA operational results (e.g., CA failures) experienced by the network node <NUM>.

In one example, it is assumed that the network node <NUM> (NN) configures the wireless device <NUM> with information (e.g., resources) related to both <NUM>-step RACH and <NUM>-step RACH in cell1 (where cell1 may be provided by network node <NUM>). This allows the wireless device <NUM> to send RA in cell1. Moreover, the network node <NUM> configures the time gap between PRACH and PUSCH for <NUM>-step RACH MsgA to Tg. The wireless device <NUM> selects between <NUM>-step RACH and <NUM>-step RACH depending on or based at least on the configured time gap Tg and/or the number of UL LBT failures N used for random access attempts. In one or more embodiments, a CCA failure corresponds to or includes a LBT failure. In one or more embodiments, the steps performed by the wireless device <NUM> to select between <NUM>-step RACH and <NUM>-step RACH in cell1 are described below:.

The values of parameters Hn and Htg can be pre-defined or the wireless device <NUM> can be configured with one or more values of one or more parameters by the network node <NUM> which may be the same as the first network node <NUM> (NN1) or a different network node <NUM> (e.g., NN2). The wireless device <NUM> may further be configured to determine whether the wireless device <NUM> can switch between <NUM>-step and <NUM>-step RACH based on one or both parameters, i.e., based on N or Tg or both N and Tg.

In the examples, in this embodiment, the network node <NUM> is configuring the wireless device <NUM> with any of the information that may be the same as the first network node <NUM> (NN1) or it may be a different network node <NUM>, e.g., NN2.

The processes and/or methods described herein advantageously provides some control to the network node <NUM> to steer the wireless device <NUM> to one or more specific procedures/processes when the wireless device <NUM> fails to transmit PRACH or PUSCH due to LBT failure.

For example, the number (i.e., quantity) of CCA evaluation/LBT attempts (e.g., CCA failures) that the wireless device <NUM> may perform can be same or similar between <NUM>-step RA and <NUM>-step RA when Tg is quite large (i.e., Tg > COT). In this case, there may be no clear advantage to prefer or start with the <NUM>-step RA compared to <NUM>-step RA from an LBT point of view. However, starting with the <NUM>-step RA gives more control to the network node <NUM> as the network node <NUM> can, e.g., postpone/delay the MSG3 transmission when the channel is busy in part because the network node <NUM> can perform CCA evaluation and prepare the wireless device <NUM> for MSG3 transmission. This provides an overall better RA performance as the wireless device <NUM> can more adaptively select RA type depending on the Tg. Starting with the <NUM>-step RA may not provide this flexibility to the wireless device <NUM> in the same operating scenario. That is, the quantity of CCA failures is a property associated with message <NUM> of a <NUM>-step RA (e.g., random access procedure type) as the process starts with <NUM>-step RA.

Another advantage provided by the one or more methods and/or embodiments described herein may be that the wireless device <NUM> can already, at the beginning or toward the beginning of the process, select a more suitable RA type based on the parameters described above (e.g., Tg). By selecting the proper one, in the beginning, the wireless device <NUM> avoids the risk of attempting RA using a less suitable RA type (e.g., <NUM>-step RA) and thereafter falling back to more suitable RA type (e.g., <NUM>-step RA), which may lead to more total delay for the procedure.

Some NR-U wireless device <NUM> implementations may require a delay between PRACH and PUSCH. This delay increases the amount of time needed to transmit the PRACH and PUSCH, and so a larger COT may be needed for such wireless devices <NUM>. Two-step random access allows low latency random access procedures, and so in scenarios where low latency is desirable, a network node <NUM> may choose to configure its random access resources primarily for two step operation. In these scenarios, there may be little or no <NUM>-step RACH resource available, and when the total time needed to transmit PRACH and PUSCH exceeds the COT needed for <NUM>-step operation, the wireless device <NUM> may also not be able to use <NUM>-step RACH procedures. One solution to this problem is to allow the wireless device <NUM> to transmit a RACH preamble associated with <NUM>-step operation without transmitting a msgA PUSCH. Since the network node <NUM> may not generally know the delay capability of wireless devices <NUM> prior to initial access, the network node <NUM> may not be able to infer if the configuration it provides to the wireless device <NUM> meets the wireless device <NUM>'s delay requirements, and so the network node <NUM> may not generally know if the wireless device <NUM> actually transmits a msgA PUSCH. If the network node <NUM> does not know the capability of the wireless device <NUM> prior to initial access, and the network node <NUM> does not want to use <NUM>-step access, the network node <NUM> may allow and/or configure the wireless device <NUM> to repeatedly transmit in the two step RACH procedure, and continue to attempt to decode msgA PUSCHs that are not actually transmitted; however, this may waste resources and delay the wireless device <NUM>'s access to the cell. The network node <NUM> may thus, as one alternative, indicate fallback to <NUM>-step RA operation by transmitting a fallbackRAR to the wireless device <NUM> when it receives a <NUM>-step RA preamble without receiving an associated MsgA PUSCH transmission. In another alternative, the network node <NUM> may attempt to perform energy detection on the msgA PUSCH DMRS and/or the msgA PUSCH resource elements that carry UL-SCH in order to estimate if the msgA PUSCH was actually transmitted by the wireless device <NUM>. If the network node <NUM> determines that a preamble is transmitted without a PUSCH, then the network node <NUM> can choose/select to indicate, to the wireless device <NUM>, a fallback to <NUM>-step operation such as by, for example, transmitting a fallbackRAR to the wireless device <NUM>). In this manner, those wireless devices <NUM> that do not transmit a PUSCH because the PO is too close to the RO can be directed to <NUM>-step operation, while wireless devices <NUM> that transmitted a PUSCH that was not received by the network node <NUM> can still continue to use <NUM>-step operation.

Therefore, in one or more embodiments, a wireless device <NUM> adapts a random access procedure according to a channel occupancy time (COT). The wireless device <NUM> determines a channel occupancy time for a transmission by the wireless device <NUM> using shared channel access. It also receives a first and a second configuration identifying a random access preamble occasion ('RO') and a PUSCH transmission occasion ('PO'), respectively. The wireless device <NUM> selects a random access preamble and an RO containing the preamble and identifies a PO corresponding to the RO. When the combined duration of the random access preamble, the PO, and a minimum delay is not greater than the channel occupancy time, the wireless device <NUM> transmits the PRACH and a PUSCH in the PO such that the random access preamble is followed by the PUSCH at a delay not less than the minimum delay, where the combined duration comprises the time from the start of the preamble to the end of the PO. When the combined duration of a PRACH, the PO, and the minimum delay for a wireless device <NUM> is greater than the channel occupancy time, the wireless device <NUM> transmits the random access preamble in the RO. In some such embodiments, the minimum preamble-RO delay is a wireless device <NUM> capability. In these embodiments, the wireless device <NUM> may be identified as supporting transmission of the random access preamble followed by a PUSCH at a delay not less than the minimum delay.

Example <NUM>. (wireless devices <NUM> that require a delay between PRACH and PUSCH for NR-U. If the PO is greater than a COT, fall back by transmitting only the PRACH) A method of adapting a random access procedure according to a channel occupancy time comprising:.

Example <NUM>. (The minimum preamble-RO delay is a wireless device capability) The method of Example <NUM>, wherein the wireless device <NUM> is identified as supporting transmission of the random access preamble followed by a PUSCH at a delay not less than the minimum delay.

Example A1. A network node <NUM> configured to communicate with a wireless device <NUM> (WD <NUM>), the network node <NUM> configured to, and/or comprising a radio interface <NUM> and/or comprising processing circuitry <NUM> configured to:.

Example A2. The network node <NUM> of Example A1, wherein the time gap is between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH.

Example A3. The network node <NUM> of any one of Examples A1-A2, wherein the time gap is further based on at least one parameter of the LBT procedure.

Example A4. The network node <NUM> of any one of Examples A3, wherein the at least one parameter is based at least on one of a channel occupancy time, COT, LBT failure statistics and whether the COT is configured for an unlicensed carrier.

Example A5. The network node <NUM> of any one of Examples A1-A4, wherein the processing circuitry <NUM> is configured to configure the wireless device with <NUM>-step RACH and the <NUM>-step RACH.

Example A6. The network node <NUM> of any one of Examples A1-A4, wherein the processing circuitry <NUM> is further configured to configure with wireless device <NUM> with additional time gaps between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH for selection by the wireless device <NUM>.

Example B1. A method implemented in a network node <NUM>, the method comprising:.

Example B2. The method of Example B1, wherein the time gap is between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH.

Example B3. The method of Example B1, wherein the adapting of the time gap is further based on at least one parameter of the LBT procedure.

Example B4. The method of any one of Examples B3, wherein the at least one parameter is based at least on one of a channel occupancy time, COT, LBT failure statistics and whether the COT is configured for an unlicensed carrier.

Example B5. The method of any one of Examples B1-B4, wherein the processing circuitry <NUM> is configured to configure the wireless device <NUM> with <NUM>-step RACH and the <NUM>-step RACH.

Example B6. The method of any one of Examples B1-B4, further comprising configuring with wireless device <NUM> with additional time gaps between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH for selection by the wireless device <NUM>.

Example C1. A wireless device <NUM> (WD <NUM>) configured to communicate with a network node <NUM>, the WD <NUM> configured to, and/or comprising a radio interface <NUM> and/or processing circuitry <NUM> configured to:.

Example C2. The wireless device <NUM> of Example C1, wherein the time gap is between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH.

Example C3. The wireless device <NUM> of any one of Examples C1-C2, wherein the time gap is further based on at least one parameter of the LBT procedure.

Example C4. The wireless device <NUM> of any one of Examples C3, wherein the at least one parameter is based at least on one of a channel occupancy time, COT, LBT failure statistics and whether the COT is configured for an unlicensed carrier.

Example C5. The wireless device <NUM> of any one of Examples C3-C4, wherein the processing circuitry <NUM> is further configured to:.

Example C6. The wireless device <NUM> of any one of Examples C1-C4, wherein the processing circuitry <NUM> is further configured to:.

Example D1. A method implemented in a wireless device <NUM> (WD <NUM>), the method comprising:.

Example D2. The method of Example D1, wherein the time gap is between resources used for PRACH and PUSCH transmissions in <NUM>-step RACH.

Example D3. The method of Example D1, wherein the time gap is further based on at least one parameter of the LBT procedure.

Example D4. The method of any one of Examples D3, wherein the at least one parameter is based at least on one of a channel occupancy time, COT, LBT failure statistics and whether the COT is configured for an unlicensed carrier.

Example D5. The method of any one of Examples D3-D4, further comprising:.

Example D6. The method of any one of Examples D1-D4, further comprising:.

Claim 1:
A wireless device (<NUM>), comprising:
processing circuitry (<NUM>) configured to:
receive from a network node (<NUM>), a set of configurations on MsgA transmission of a <NUM>-step Random Access, RA, procedure, wherein each configuration indicates a time gap between physical random access channel, PRACH, resources and physical uplink shared channel, PUSCH, resources for the MsgA transmission;
determine a time gap length out of the indicated time gaps based at least on the configurations and on clear channel assessment, CCA, operational results that include results of CCA failure or CCA success obtained by the network node (<NUM>) and received by the wireless device (<NUM>) from the network node (<NUM>); and
transmit a MsgA in a <NUM>-step RA procedure based on the determined time gap length.