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1. (WO2019029668) IMPROVEMENTS IN OR RELATING TO SIGNALLING ASPECTS OF UPLINK DATA TRANSMISSIONS
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Improvements in or relating to signalling aspects of Uplink data transmissions

Technical Field

Embodiments of the present invention generally relate to wireless communication systems and in particular to devices and methods for enabling a wireless communication device, such as a User Equipment (UE) or mobile device to access a Radio Access Technology (RAT) or Radio Access Network (RAN), particularly but nor exclusively to signalling aspects of uplink (UL) data transmissions.

Background

Wireless communication systems, such as the third-generation (3G) of mobile telephone standards and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project (3GPP). The 3rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Communication systems and networks have developed towards a broadband and mobile system.

The 3rd Generation Partnership Project has developed the so-called Long Term Evolution (LTE) system, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN), for a mobile access network where one or more macro-cells are supported by a base station known as an eNodeB or eNB (evolved NodeB). More recently, LTE is evolving further towards the so-called 5G or NR (new radio) systems where one or more cells are supported by a base station known as a gNB.

In data transmissions between a mobile device and radio network in NR there is a requirement to meet a broad range of use cases including among others enhanced mobile broadband, ultra-reliable low latency communications (URLLC) and massive machine type communications for which optimal data transmission is sought for. Uplink data transmission without grant is a new feature introduced for NR.

A Radio Access Network system architecture for NR is as follows. The Next Generation (NG)-RAN consists of gNBs, providing the user plane and control plane protocol terminations towards the UE. The gNBs are interconnected with each other by means of the so called Xn interface. The gNBs are also connected by means of an NG interface to the Next Generation Core (NGC) and more specifically to the AMF (Access and Mobility Management Function) by means of the N2 interface and to the UPF (User Plane Function) by means of the N3 interface.

The NG-RAN architecture is illustrated in Figure 1. The gNB hosts, among others, the following functions: Functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling).

Figure 2 shows a protocol stack for a control plane, where Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC) and Medium Access Control (MAC) sublayers (terminated in gNB on the network side) perform their normal functions. Radio Resource Control (RRC) (terminated in gNB on the network side) performs at least the function of maintenance of the RRC connection and associated Layer 2 (PDCP/RLC/MAC) and physical radio resources between the UE and NG-RAN. A Non-Access Stratum (NAS) control protocol (terminating in an Access Management Function (AMF) on the network side) performs their normal functions. Typically, RRC supports the following states which can be characterised as follows: RRCJDLE; RRCJNACTIVE and RRC_CONNECTED. RRCJDLE includes Public Land Mobile Network (PLMN) selection; broadcast of system information; cell re-selection mobility; paging (initiated and area managed by 5GC); and Discontinuous Transmission (DRX) for Core Network (CN) paging configured by NAS. RRCJNACTIVE, includes broadcast of system information; cell re-selection mobility; 5GC - NG-RAN connection (both Control/User-planes) is established for UE; the UE AS context is stored in at least one gNB and the UE; paging is initiated by NG-RAN; DRX for NG-RAN paging configured by NG-RAN; RAN-based notification area (RNA) is managed by NG- RAN; NG-RAN knows the RNA which the UE belongs to; and data transmission. RRC_CONNECTED includes the UE has an NG-RAN RRC connection; the UE has an AS context in NG-RAN; NG-RAN knows the cell which the UE belongs to; transfer of unicast data to/from the UE; and network controlled mobility including measurements.

The User plane protocol stack for NR is shown in figure 3, which shows the protocol stack for the user plane, where PDCP, RLC and MAC sublayers (terminated in gNB on the network side) perform similar functions as LTE. The main services and functions of the PDCP sublayer for the user plane include at least transfer of user data.

The main services and functions of the RLC sublayer include at least the transfer of upper layer Protocol Data Units (PDUs), according to transmission modes Acknowledged Mode (AM), Unacknowledged Mode (UM) and Transparent Mode (TM). The main services and functions of the MAC sublayer include at least a number of functions. One function is mapping between logical channels and transport channels. Another is multiplexing/demultiplexing of MAC Service Data Units (SDUs) belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels. A further is scheduling information reporting.

The Layer 2 Data Flow depicted in figure 4 shows a transport block generated by MAC by concatenating two Radio Link Control (RLC) PDUs from Radio Bearer x (RBx) and one RLC PDU from RBy. The two RLC PDUs from RBx each corresponds to one IP packet (n and n+1) while the RLC PDU from RBy is a segment of an IP packet (m). H depicts the headers and subheaders.

In order to utilise radio resources efficiently, MAC in gNB includes dynamic resource schedulers that allocate physical layer resources for the downlink and the uplink. An overview of the scheduler is given in terms of scheduler operation, signalling of scheduler decisions, and measurements. Scheduler Operation takes into account a number of different points. Based on the UE buffer status and the QoS requirements of each UE and associated radio bearers, schedulers assign resources between UEs. Schedulers may assign resources taking account the radio conditions at the UE identified through measurements made at the gNB and/or reported by the UE. Schedulers also assign radio resources in a unit of TTI (e.g. one mini-slot, one slot, or multiple slots). Grant-based dynamic or semi-persistent scheduling (SPS) Resource assignment consists of radio resources or resource blocks.

The signalling of Scheduler Decisions is also important. UEs identify the resources by receiving a scheduling (resource assignment) channel. The Support Scheduler Operation measurements are further worthy of mention. Uplink buffer status reports (measuring the data that is buffered in the logical channel queues in the UE) are used to provide support for Quality of service (QoS)-aware packet scheduling. The buffer reporting scheme used in uplink is flexible to support different types of data services. Constraints on how often uplink buffer reports are signaled limits the overhead from sending the reports in the uplink.

In the downlink, the gNB can dynamically allocate resources to UEs at each TTI. A UE always monitors the downlink in order to find possible allocation when its downlink reception is enabled (activity governed by DRX when configured). In addition, NR can periodically allocate semi-persistent downlink resources for a first Hybrid Automatic Repeat reQuest (HARQ) transmissions to UEs via RRC. RRC defines the periodicity of the semi-persistent downlink grant. A Physical Dedicated Control Channel (PDCCH) indicates when the downlink grant is a semi-persistent one i.e. whether it can be implicitly reused in the following TTIs according to the periodicity defined by RRC.

From the DCI Downlink Control Indicator format (Layer 1 signaling) within the PDCCH required, the UE knows how to get its data which is transmitted on PDSCH in the same subframe from the resource grid. The DCI format gives the UE, details such as number of resource blocks, resource allocation type, modulation scheme, transport block, redundancy version, coding rate etc. Each DCI format, when encoding is attached with a CRC that is scrambled with the UE-Radio Network Temporary Identifier (UE-RNTI) (in the context of Semi Persistent Processing SPS, such as Radio Network Temporary Identifier (RNTI), this may be called SPS RNTI) to which the Physical Downlink Shared Channel (PDSCH) is intended to. So only that UE can decode the Downlink Control Information (DCI) format and hence the corresponding PDSCH.

In the uplink, the gNB can dynamically allocate resources to UEs at each TTI. A UE always monitors the downlink in order to find possible allocation for uplink transmission when its downlink reception is enabled (activity governed by DRX when configured). In addition, NR can periodically allocate semi-persistent uplink resources for the first HARQ transmissions to UEs via RRC but when the UE does not have any data to transmit, it ignores such resources.

In addition, taking LTE as a baseline, NR can allocate a semi-persistent uplink resource for the first HARQ transmissions and potentially retransmissions to UEs. RRC defines the periodicity of the semi-persistent uplink grant. PDCCH indicates whether the uplink grant is a semi-persistent one i.e. whether it can be implicitly reused in the following TTIs according to the periodicity defined by RRC.

Similarly to downlink scheduling case, the SPS RNTI is used by the UE to scramble the Cyclic Redundancy Check (CRC) of the data to be sent on the Physical Uplink

Shared Channel (PUSCH). As a result, the network can decode such data from the UE.

Transmission without grant consists of pre-allocation of semi-static physical time/frequency resources to multiple UEs used for transmission. UEs can be differentiated based on Reference Signal (DMRS) specific to each UE. Two different types of UL transmission without grant have been agreed in the standard.

Type 1 relates to UL data transmission without grant only based on RRC (re)configuration without any L1 signalling. In this case, RRC (reconfiguration includes at least the following considerations. A periodicity and offset of a resource with respect to SFN=0. Time domain resource allocation and Frequency domain resource allocation are used. There is UE-specific DMRS configuration and a Modulation and Coding Scheme (MCS)/TBS value. The number of HARQ repetitions is K. Power control related parameters and HARQ related parameters are used and determination of whether multiple resources are to be used, remain open.

Type 2 relates to UL data transmission without grant is based on both RRC configuration and L1 signalling to activation/deactivation for UL data transmission without grant. In this case the functionality of modification is achieved through L1 signalling by activation. RRC (re-) configuration for resource and parameters includes at least the following: periodicity of a resource and power control related parameters. The following additional parameters for the resource are given by L1 signalling. Offset is associated with the periodicity with respect to a timing reference indicated by L1 signalling for activation. Time domain resource allocation and Frequency domain resource allocation are used. UE-specific DMRS configuration and an MCS/TBS value are used. Whether multiple resources can be configured; whether HARQ related parameters are used and the timing reference remain open. Whether the number of repetitions K is configured by RRC signalling and/or indicated by L1 signalling is also undecided.

Type 1 is different from type 2 at least on the point that any L1 signalling is not required, and type 2 has some similarity with LTE UL SPS at least on the point that L1 signalling is used for activation/deactivation.

Type 3 might be implemented for UL data transmission without grant based on RRC configuration, allowing L1 signalling to modify some parameters configured by RRC but no L1 signalling for activation.

To enable the UL data transmission without grant feature for the UE, the man skilled in the art would come to the solution to introduce two RRC messages one for either type, implying more impact to the standards. Such a "basic" solution would obviously be workable.

In reality such a simple solution is unlikely to be enough and this the problems still exist and are unresolved.

The present invention is seeking to solve at least some of the outstanding problems in this domain.

Summary

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

According to a first aspect of the present invention there is provided a method for enabling a wireless communication device to access services provided by a Radio Access Network to enable a data transmission for a wireless communications device, the method comprising including an indication in a control message to generate a Control reconfiguration related to a transmission without grant.

Preferably, the control message is a Radio Resource Control message and the control configuration is a Radio Resource control configuration.

Preferably, the indication is included in a semi-persistent scheduling information element.

Preferably, the transmission comprises at least one of an uplink transmission without grant and a downlink transmission without grant

Preferably, the indication comprises at least one of a follow-up layerl activation signal indicator; and a semi-persistent scheduling Radio Network Temporary Identifier.

6. The method of claim 5, wherein the follow-up layerl activation signal indicator includes at least one of: an offset of a resource with respect to System Frame

Number=0, a time domain resource allocation, frequency domain resource allocation, a UE-specific DMRS configuration, and an MCS/TBS value.

Preferably, the semi-persistent scheduling Radio Network Temporary Identifier relates to transmission without grant.

Preferably, the method further comprises using the Radio Network Temporary Identifier to determine whether layeM signalling is awaited.

Preferably, upon receipt of the Radio Resource Control reconfiguration the wireless communications device determines transmission without grant is operating.

Preferably, when transmission without grant is operating the wireless communications device identifies the indication to determine whether to await further signalling or perform transmission without requiring further signalling.

Preferably, the method further comprises configuring the indication.

Preferably, the Radio Access Network is a New Radio/5G network.

According to a second aspect of the present invention there is provided a base station adapted to perform the method of another aspect of the present invention.

According to a third aspect of the present invention there is provided a UE adapted to perform the method of another aspect of the present invention.

According to a fourth aspect of the present invention there is provided a non-transitory computer readable medium having computer readable instructions stored thereon for execution by a processor to perform the method of another aspect of the present invention.

The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.

Brief description of the drawings

Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the respective drawings to ease understanding.

Figure 1 is a diagram of a simple overall architecture, according to the prior art.

Figure 2 is a diagram of a protocol stack for a control plane, according to the prior art.

Figure 3 is a diagram of a User plane protocol stack, according to the prior art.

Figure 4 is a diagram of a data flow example, according to the prior art.

Figure 5 is a diagram of a Layer1 signalling activation control scheme, according to an embodiment of the present invention.

Figure 6 is a diagram of another Layer1 signalling activation control scheme, according to an embodiment of the present invention.

Detailed description of the preferred embodiments

Those skilled in the art will recognise and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

The invention is intended to provide means to control the activation of physical layer signalling by higher layer signalling. In the context of NR, this can be used to fulfil the requirements of uplink data transmission without grant. The solution consists in reusing the same RRC procedure to control whether the UE can expect some further physical layer signalling prior to actually perform uplink data transmission.

One use case of uplink data transmission without grant is to an RRC connection-less (i.e. RRCJnactive state) UE where resources without grant can be reserved to multiple UEs. When one such UE receives an RRC connection (RRC_Connected state), its resources would be reconfigured to become UE specific ones. However, whatever the resources are with grant when SPS applies, or without where uplink data transmission without grant applies, the RRC and Layer1 parameters are similar.

As a result, whenever the UE moves between Inactive and Connected states, resources reconfiguration between SPS and uplink data transmission without grant have to be considered. Reusing the same parameters as SPS (re)configuration would allow having one rather than two sets of parameters (one to release/configure those uplink data transmission without grant resources, the other to configure/release those SPS resources).

Therefore, the same RRC reconfiguration message could be reused for SPS. The relatively few parameters from SPS that are not applicable to uplink data transmission without grant may be subject to a conditional configuration.

For example, ImplicitReleaseAfter used in SPS, is meant to implicit release the SPS configuration. However, in uplink data transmission without grant, the configuration is never released in Type 1 but released by explicit L1 deactivation signalling. Hence, there is no implicit release configuration in uplink data transmission without grant compared with SPS.

The current LTE based RRC SPS configuration is always followed by L1 signalling activation then the UE can use the configured SPS grants/assignments. Therefore, the reused RRC SPS reconfiguration message has to consider whether L1 signalling should be waited for (i.e. uplink data transmission without grant Type 1 ) or not (i.e. uplink data transmission without grant Type 2).

From the differences between Type 1 and Type 2, if the following L1 parameters (those for Type 1 but not present for Type 2) are present in the RRC configuration. These include offset of a resource with respect to SFN=0; time domain resource allocation; frequency domain resource allocation; UE-specific DMRS configuration; and an MCS/TBS value. The number of repetitions of K remains open. From the above, the UE would infer Type 1 and can perform UL transmission without awaiting further L1 signalling.

Using RRC to check the presence of a set of Layer1 parameters might not be so beneficial because apart from forwarding to Layer1 , such parameters would not directly influence RRC functions. Besides such checking is currently not performed by RRC for any Layer1 parameters. Accordingly, to infer Type 1, the UE would need to check eight parameters from RRC signalling; and to infer Type 2, the UE would need to check two parameters from RRC signalling.

To reduce the number of checks at the UE, the minimal number of parameters are checked to allow discrimination between Type 1 and Type 2. For example, only one check is made among parameters present in RRC for Type 1 but absent for Type 2 e.g. one among: offset of a resource with respect to SFN=0, time domain resource allocation, frequency domain resource allocation, UE-specific DMRS configuration, an MCS/TBS value.

Another consideration which needs to be considered, is flexibility in configuration with the above mentioned considerations.

For example, uplink data transmission without grant Type 3 is currently open, but is relevant to the present invention. Type 3 has additional benefits over agreed Type 1 in that, after RRC configuration and UL transmission activation, modification of some Layerl parameters can occur, as in MCS/TBS, to address changing radio conditions. Such behaviour is indeed not possible with Type 1 (Layerl parameters modification is not possible therein) but Type 2.

A solution where a "Layerl signalling activation Follow up" indication enables the UE to infer whether to wait for L1 signalling activation ahead of UL transmission is independent of the open issue Type in RAN1. Actually for Type3, such indication would be applicable and set as for Type 1 (i.e. "Layerl signalling activation Follow up" is not set).

As a result the abovementioned solution, may complete the RRC configuration specification regardless of RAN1 feedback in support of Type 3 and regardless of the RAN1 parameters specification.

The same RRC message including a "Follow up L1 activation signalling" indication for uplink data transmission without grant resource (re)configuration allows the UE to know whether it can expect L1 signalling prior to performing uplink transmission. This has a number of advantages over the known solutions.

This can alternatively be inferred by checking only one L1 parameter in the RRC message specific to uplink data transmission without grant Type 1 and not present for uplink data transmission without grant Type 2.

An advantage of the invention is that UE processing timing is decreased (by avoiding to check on all L1 parameters) and hence to target the low latency requirement of 0.5ms for the further user plane data transmission as is required for NR is an advantage of the present invention. Another advantage includes the reduction in UE processing time that can be estimated to be between 2 and 8 times depending on the number of checked L1 parameters. The specification impacts of avoiding duplicated configurations and reusing SPS to configure uplink data transmission without grant Type 2 are another advantage. Downlink data transmission without grant can also be achieved by this solution.

The following detailed description of one or more embodiments adds further to the features and advantages of the present invention.

Figure 5 illustrates one embodiment where a new indication is included in an RRC configuration message along with SPSs. This embodiment can be used in the scenario where uplink transmission without grant configuration is changed between Type 1 and Type 2. Switching from Type 1 to Type 2 is needed when Layer 1 parameters need to be tuned due to changing radio conditions, for example to update the MCS to allow for higher/less data size transmission or to update number of retransmissions. Conversely, switching from Type 2 to Type 1 is needed when Layer 1 parameters no more need to be tuned due to stable radio conditions.

At step 1 , knowing that the UE supports the uplink data transmission without grant feature based e.g. UE capabilities or UE subscription, the radio network provides uplink data transmission without grant radio resources via an RRC reconfiguration message. Such message can include updated SPS parameters. The message additionally include an indication of whether Layer1 signalling for activation of uplink data transmission is expected. This indication is meant for the UE to know that expected Layer1 signalling would control the allocation of resources ahead of initial transmission. Resources can be activated, modified or deactivated. The indication can take the form of the conditional presence of a bunch of specific Layer1 parameters to Type 1 within or separate from SPS configuration. The optional presence of such parameters within SPS configuration has the advantage of minimizing ASN1 (Abstract Syntax Notation.1 ) based encoding RRC signalling. In this way, an additional and separate configuration including that bunch is avoided.

In addition, only one round trip of SPS configuration is necessary to switch between Type 1 and Type 2 instead of one SPS configuration to release Type 1/2 and another one to configure Type 2/1. It is highly advantageous to have only one RRC configuration for switching because in case uplink data is pending for transmission in the UE, they can be already sent to the network and thus the very low latency (of 0.5ms) to deliver them to the network can be met. In case the UE has to wait for the second reconfiguration which should be received by the network at least 15ms later. From the RRC specification (TS 36.331 section Processing delay requirements), the UE sends the (first) reconfiguration response message after 15ms upon receipt of