GB2621312A

GB2621312A - Apparatus, method and computer program

Info

Publication number: GB2621312A
Application number: GB2210394.9A
Authority: GB
Inventors: Deghel Matha; Lehti Arto
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2022-07-15
Filing date: 2022-07-15
Publication date: 2024-02-14
Also published as: GB202210394D0

Abstract

An apparatus comprising a means for determining a waveform to be used for transmitting a random-access procedure from a user equipment (UE). The waveform may be cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) or Discrete Fourier Transform Spread orthogonal frequency division multiplexing (DFT-S-OFDM). The UE provides an indication to the base station of the selected waveform. The indication may be provided using: a PUSCH occasion, DMRS for PUSCH, a message preamble, a RACH occasion associated with the waveform, and uplink control information (UCI). The message to be transmitted may be MsgA of a 2-step RACH procedure. Alternatively, the message may be Msg3 in a 4-step RACH procedure, wherein Msg1 is used to provide the indication. The base station may provide an indication to confirm or change the determined waveform. Pathloss measurements may be made. The waveform may be determined using thresholds. The threshold may comprise a number of preamble transmissions.

Description

Intellectual Property Office Application No GI322103949 RTM Date:2 December 2022 The following terms are registered trade marks and should be read as such wherever they occur in this document: 3 GP P LIE UMT S Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo Title Apparatus, method and computer program

Field

The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to waveform switching for Random Access Channel (RACH) procedures.

Background

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, video, electronic mail (email), text message, multimedia and/or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

In a wireless communication system at least a part of a communication session between at least two stations occurs over a wireless link. Examples of wireless systems comprise public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (VVLAN). Some wireless systems can be divided into cells, and are therefore often referred to as cellular systems.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user may be referred to as user equipment (UE) or user device. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station, for example a base station of a cell, and transmit and/or receive communications on the carrier.

The communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is UTRAN (3G radio). Other examples of communication systems are the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology and so-called 5G or New Radio (NR) networks. NR is being standardized by the 3rd Generation Partnership Project (3GPP).

Summary

In a first aspect there is provided an apparatus comprising means for determining a waveform to be used for transmitting a message of a random access procedure from a user equipment and providing an indication of the determined waveform to a base station from the user equipment.

The apparatus may comprise means for providing the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, 20 DMRS, for PUSCH, a message preamble or a random access channel, RACH, occasion associated with the determined waveform.

The apparatus may comprise means for receiving a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion from the base station.

The DM RS for PUSCH may comprise at least one of the following: DM RS resources, DM RS sequence, DM RS cyclic shift or orthogonal cover codes.

The apparatus may comprise means for providing the indication using uplink control information.

The message may be MsgA of a 2-step random access procedure.

MsgA may comprise a plurality of PUSCH occasions and the apparatus may comprise means for causing the first PUSCH of the plurality of PUSCH occasions to be transmitted with a default waveform and the remainder of the plurality of the PUSCH occasions to be transmitted with the determined waveform.

The message may be Msg3 of a 4-step RACH procedure and the apparatus may comprise means for providing the indication using Msgl of the 4-step random access procedure.

The apparatus may comprise means for, in response to providing the indication, receiving information comprising an indication from the base station to change or confirm the determined waveform.

The apparatus may comprise means for determining the waveform from one of a cyclic prefix orthogonal frequency division multiplexing, CP-OFDM, waveform, and a discrete Fourier transform spread orthogonal frequency division multiplexing, DFT-s-OFDM, waveform.

The apparatus may comprise means for determining the waveform based on a threshold.

The threshold may be a measurement criteria threshold The measurement criteria may comprise a pathloss measurement.

The threshold may comprise a number of preamble transmissions.

In a second aspect there is provided an apparatus comprising means for receiving, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.

The apparatus may comprise means for receiving the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, DMRS, for PUSCH, a message preamble or random access channel, RACH, occasion associated with the determined waveform.

The apparatus may comprise means for providing a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion to the user equipment.

The apparatus may comprise means for receiving the indication using uplink control information.

The waveform may be one of a cyclic prefix orthogonal frequency division multiplexing, CP-OFDM, waveform, and a discrete Fourier transform spread orthogonal frequency division multiplexing, DFT-s-OFDM, waveform.

The message may be MsgA of a 2-step random access procedure.

The message may be Msg3 of a 4-step RACH procedure and the apparatus may comprise means for receiving the indication using Msg1 of the 4-step random access procedure.

The apparatus may comprise means for, in response to receiving the indication, providing an indication from the base station to change or confirm the determined waveform.

In a third aspect there is provided a method comprising determining a waveform to be used for transmitting a message of a random access procedure from a user equipment and providing an indication of the determined waveform to a base station from the user equipment.

The method may comprise providing the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, DMRS, for PUSCH, a message preamble or a random access channel, RACH, occasion associated with the determined waveform.

The method may comprise receiving a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion from the base station.

The DMRS for PUSCH may comprise at least one of the following: DMRS resources, DMRS sequence, DMRS cyclic shift or orthogonal cover codes.

The method may comprise providing the indication using uplink control information.

The message may be MsgA of a 2-step random access procedure.

MsgA may comprise a plurality of PUSCH occasions and the method may comprise causing the first PUSCH of the plurality of PUSCH occasions to be transmitted with a default waveform and the remainder of the plurality of the PUSCH occasions to be transmitted with the determined waveform.

The message may be Msg3 of a 4-step RACH procedure and the method may comprise providing the indication using Msgl of the 4-step random access procedure.

The method may comprise, in response to providing the indication, receiving information comprising an indication from the base station to change or confirm the determined waveform.

The method may comprise determining the waveform from one of a cyclic prefix orthogonal frequency division multiplexing, CP-OFDM, waveform, and a discrete Fourier transform spread orthogonal frequency division multiplexing, DFT-s-OFDM, waveform.

The method may comprise determining the waveform based on a threshold.

The threshold may comprise a number of preamble transmissions.

In a fourth aspect there is provided a method comprising receiving, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.

The method may comprise receiving the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, DMRS, for PUSCH, a message preamble or random access channel, RACH, occasion associated with the determined waveform.

The method may comprise providing a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion to the user equipment.

The method may comprise receiving the indication using uplink control information.

The waveform may be one of a cyclic prefix orthogonal frequency division multiplexing, CPOFDM, waveform, and a discrete Fourier transform spread orthogonal frequency division multiplexing, DFT-s-OFDM, waveform.

The message may be MsgA of a 2-step random access procedure.

The message may be Msg3 of a 4-step RACH procedure and the method may comprise receiving the indication using Msgl of the 4-step random access procedure.

The method may comprise, in response to receiving the indication, providing an indication from the base station to change or confirm the determined waveform.

In a fifth aspect there is provided an apparatus comprising: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to determine a waveform to be used for transmitting a message of a random access procedure from a user equipment and provide an indication of the determined waveform to a base station from the user equipment.

The apparatus may be caused to provide the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, DMRS, for PUSCH, a message preamble or a random access channel, RACH, occasion associated with the determined waveform.

The apparatus may be caused to receive a configuration of the association between the 30 waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion from the base station.

The DMRS for PUSCH may comprise at least one of the following: DMRS resources, DMRS sequence, DMRS cyclic shift or orthogonal cover codes The apparatus may be caused to provide the indication using uplink control information.

The message may be MsgA of a 2-step random access procedure.

MsgA may comprise a plurality of PUSCH occasions and the apparatus may be caused to cause the first PUSCH of the plurality of PUSCH occasions to be transmitted with a default waveform and the remainder of the plurality of the PUSCH occasions to be transmitted with the determined waveform.

The message may be Msg3 of a 4-step RACH procedure and the apparatus may be caused to provide the indication using Msg1 of the 4-step random access procedure.

The apparatus may be caused to, in response to providing the indication, receive information comprising an indication from the base station to change or confirm the determined waveform.

The apparatus may be caused to determine the waveform from one of a cyclic prefix orthogonal frequency division multiplexing, CP-OFDM, waveform, and a discrete Fourier transform spread orthogonal frequency division multiplexing, DFT-s-OFDM, waveform.

The apparatus may be caused to determine the waveform based on a threshold.

The threshold may comprise a number of preamble transmissions.

In a sixth aspect there is provided an apparatus comprising: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to receive, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.

The apparatus may be caused to receive the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, DMRS, for PUSCH, a message preamble or random access channel, RACH, occasion associated with the determined waveform.

The apparatus may be caused to provide a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion to the user equipment.

The apparatus may be caused to receive the indication using uplink control information.

The message may be MsgA of a 2-step random access procedure.

The message may be Msg3 of a 4-step RACH procedure and the apparatus may be caused to receive the indication using Msg1 of the 4-step random access procedure.

The apparatus may be caused to, in response to receiving the indication, provide an indication from the base station to change or confirm the determined waveform.

In a seventh aspect there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: determining a waveform to be used for transmitting a message of a random access procedure from a user equipment and providing an indication of the determined waveform to a base station from the user equipment.

The apparatus may be caused to perform providing the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, 30 DMRS, for PUSCH, a message preamble or a random access channel, RACH, occasion associated with the determined waveform.

The apparatus may be caused to perform receiving a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion from the base station.

The apparatus may may be caused to perform providing the indication using uplink control information.

The message may be MsgA of a 2-step random access procedure.

MsgA may comprise a plurality of PUSCH occasions and the apparatus may be caused to perform causing the first PUSCH of the plurality of PUSCH occasions to be transmitted with a default waveform and the remainder of the plurality of the PUSCH occasions to be transmitted with the determined waveform.

The message may be Msg3 of a 4-step RACH procedure and the apparatus may be caused to perform providing the indication using Msg 1 of the 4-step random access procedure.

The apparatus may be caused to perform, in response to providing the indication, receiving information comprising an indication from the base station to change or confirm the determined waveform.

The apparatus may be caused to perform determining the waveform from one of a cyclic prefix orthogonal frequency division multiplexing, CP-OFDM, waveform, and a discrete Fourier transform spread orthogonal frequency division multiplexing, DFT-s-OFDM, waveform.

The apparatus may be caused to perform determining the waveform based on a threshold.

The threshold may comprise a number of preamble transmissions.

In an eighth aspect there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.

The apparatus may be caused to perform receiving the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, DMRS, for PUSCH, a message preamble or random access channel, RACH, occasion associated with the determined waveform.

The apparatus may be caused to perform providing a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion to the user equipment.

The apparatus may be caused to perform receiving the indication using uplink control information.

The message may be MsgA of a 2-step random access procedure.

The message may be Msg3 of a 4-step RACH procedure and the apparatus may may be caused to perform receiving the indication using Msg1 of the 4-step random access procedure.

The apparatus may be caused to perform, in response to receiving the indication, providing an indication from the base station to change or confirm the determined waveform.

In a ninth aspect there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the third or fourth aspect.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

Description of Figures

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which: Figure 1 shows a schematic diagram of an example 5GS communication system; Figure 2 shows a schematic diagram of an example mobile communication device; Figure 3 shows a schematic diagram of an example control apparatus; Figure 4a shows a signalling flow for an example 4-step random access procedure; Figure 4b shows a signalling flow for an example 2-step random access procedure; Figure 5 shows a block diagram of a mapping of M preamble groups to M MsgA PUSCH occasions; Figure 6 shows a block diagram of a PUSCH occasion with control and data resource elements; Figure 7 shows a signalling flow for an example 2-Step random access procedure with analog beamforming; Figure 8 shows a flowchart of a method according to an example embodiment; Figure 9 shows a flowchart of a method according to an example embodiment; Figure 10 shows a signalling flow between a UE and a gNB according to an example embodiment.

Detailed description

Before explaining in detail the examples, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figures 1 to 3 to assist in understanding the technology underlying the described 35 examples.

An example of a suitable communications system is the 5G or NR concept. Network architecture in NR may be similar to that of LTE-advanced. Base stations of NR systems may be known as next generation Node Bs (gNBs). Changes to the network architecture may depend on the need to support various radio technologies and finer QoS support, and some on-demand requirements for e.g. Quality of Service (QoS) levels to support Quality of Experience (QoE) for a user. Also network aware services and applications, and service and application aware networks may bring changes to the architecture. Those are related to Information Centric Network (ICN) and User-Centric Content Delivery Network (UC-CDN) approaches. NR may use multiple input -multiple output (M IMO) antennas, many more base stations or nodes than the LIE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

Future networks may utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into "building blocks" or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent.

Figure 1 shows a schematic representation of a 5G system (5GS) 100. The 5GS may comprise a user equipment (UE) 102 (which may also be referred to as a communication device or a terminal), a 5G radio access network (5GRAN) 104, a 5G core network (5GCN) 106, one or more application functions (AF) 108 and one or more data networks (DN) 110.

An example 5G core network (CN) comprises functional entities. The 5GCN 106 may comprise one or more access and mobility management functions (AM F) 112, one or more session management functions (SMF) 114, an authentication server function (AUSF) 116, a unified data management (UDM) 118, one or more user plane functions (UPF) 120, a unified data repository (UDR) 122 and/or a network exposure function (NEF) 124. The UPF is controlled by the SMF (Session Management Function) that receives policies from a PCF (Policy Control Function).

The CN is connected to a UE via the radio access network (RAN). The 5GRAN may comprise one or more gNodeB (GNB) distributed unit functions connected to one or more gNodeB (GNB) centralized unit functions. The RAN may comprise one or more access nodes.

A User Plane Function (UPF) referred to as PDU Session Anchor (PSA) may be responsible for forwarding frames back and forth between the DN and the tunnels established over the 5G towards the UE(s) exchanging traffic with the DN.

A possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 200. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a 'smart phone', a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, voice over IP (VolP) phones, portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart devices, wireless customer-premises equipment (CPE), or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts and other information.

A mobile device is typically provided with at least one data processing entity 201, at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204. The user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

The mobile device 200 may receive signals over an air or radio interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2 transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

Figure 3 shows an example of a control apparatus 300 for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, eNB or gNB, a relay node or a core network node such as an MME or S-GW or P-GW, or a core network function such as AMF/SMF, or a server or host. The method may be implemented in a single control apparatus or across more than one control apparatus. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some embodiments, base stations comprise a separate control apparatus unit or module. In other embodiments, the control apparatus can be another network element such as a radio network controller or a spectrum controller. In some embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 300 can be arranged to provide control on communications in the service area of the system. The control apparatus 300 comprises at least one memory 301, at least one data processing unit 302, 303 and an input/output interface 304. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head.

Different waveforms have different requirements and/or considerations in terms of frequency and time domain allocations, power allocation etc. For example, discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) waveform has lower peak to average power ratio (PAPS) compared with cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform. Compared to CP-OFDM, DFT-S-OFDM may be more suitable in case of power-limited scenarios. Specifically, DFT-S-OFDM may be more suitable for cell edge UEs, or more generally, for UEs experiencing coverage limitations, e.g. higher frequency bands (mmwave, THz), both in DL and UL, non-terrestrial networks etc. In earlier NR releases the waveform used for the uplink transmission (CP-OFDM, DFT-S-OFDM) has been configured using radio resource control (RRC). As a result, changing the waveform requires RRC reconfiguration. This limitation may impose a practical barrier to switch over to DFT-S-OFDM waveform for cell-edge UEs.

Uplink coverage enhancements for physical random access channel (PRACH), power domain and DFT-S-OFDM, such as dynamic switching between DFT-S-OFDM and CPOFDM waveforms, are being considered. When a waveform is switched dynamically, RRC reconfiguration is not needed for the switching.

One key feature for which the dynamic waveform switching would need to be defined in 3GPP is a random access procedure (also referred to as a RACH procedure) such as the two-step RACH procedure (or the four-step RACH procedure). This may be important to dynamically adapt and apply a suitable waveform to the PUSCH transmissions within RACH procedures.

The 4-step RACH procedure is supported in Rel-15 NR. The basic procedure is shown in Figure 4a. In Msg1, a UE sends a random access preamble to a gNB. In Msg2, the gNB sends a random access response. In Msg3, the UE sends the scheduled transmission and in Msg4, the gNB sends contention resolution.

A 2-step RACH procedure for NR has been agreed. Specifically, channel structure and related procedure has been designed in RAN. Compared with the 4-step procedure, a 2-step RACH procedure may have benefits for channel access and for enhancing the connection setup/resume procedure providing improved latency of the random access procedure.

The basic procedure for a 2-step RACH procedure is shown in Figure 4b. In a 2-step RACH procedure, MsgA from the UE to the gNB combines the preamble signal (Msg1) and the data signal (Msg3), and MsgB from the gNB to the UE combines the random-access response (Msg2) and the contention resolution (Msg4).

Events triggering a 2-step RACH procedure may be the same as for a 4-step RACH procedure. Some of those events are, but not limited to, initial access from RRC_IDLE, RRC Connection Re-establishment procedure, DL or UL data arrival during RRC_CONNECTED when UL synchronisation status is "non-synchronised", UL data arrival during RRC CONNECTED when there are no physical uplink control channel (PUCCH) resources for SR available, SR failure, request by RRC upon synchronous reconfiguration (e.g. handover), transition from RRC_INACTIVE, to establish time alignment at secondary cell (SCell) addition, an system information (SI) Request and beam failure recovery (BFR).

Existing specifications support one-to-one and multiple-to-one mapping between preambles in each RO (RACH occasion) and associated physical uplink shared channel (PUSCH) resource unit. In the case of one-to-one mapping, each preamble would require a separate PUSCH resource unit, whereas in the case of multiple-to-one mapping multiple preambles are mapped to the same PUSCH resource unit. With one-to-one mapping, there will be no collision between two UEs that choose different preambles, however this kind of mapping would require a quite high PUSCH resource reservation. On the other hand, multiple-to-one mapping is a much more resource efficient approach, however with such mapping (even with two different preambles) there is a risk of collision on the PUSCH resources.

An example of multiple-to-one mapping between preambles and PUSCH occasions is shown in Figure 5, where each PUSCH occasion has K PUSCH resource units and K < N. To improve the decodability of MsgA at the gNB, the UE may select different modulation and coding schemes (MCS) depending on the measured channel conditions. However, trying multiple decode hypothesis at the gNB increases the complexity of the gNB receiver. To avoid this, uplink control information (UCI) including, for example, the MCS, payload and resource size, etc. may be transmitted with the uplink data to assist the gNB to decode the MsgA PUSCH transmission and hence reduce the number of hypothesis testing and subsequent risk of erroneous decoding.

An illustration of MsgA containing UCI is given in Figure 6.

In NR, with analog beamforming, there is an association of the different SSB time indices with different ROs On time and frequency) and/or different preambles. Since different SSB time indices correspond to SSB transmissions in different downlink beams, based on the detected preamble, the network will be able to know the selected beam for the user who has transmitted this preamble. The network can then use this beam for downlink transmissions to this user.

An illustration example of a 2-step RACH procedure with beamforming is given in Figure 7.

Based on the existing specifications, the UE is provided via RRC configuration (MsgA or Msg3 configuration) with the waveform to apply for MsgA (or Msg3) PUSCH transmissions.

The following focusses on dynamic waveform switching considering random access procedures.

Figure 8 shows a flowchart of a method according to an example embodiment. The method may be performed at a user equipment.

In Si, the method comprises determining a waveform to be used for transmitting a message of a random access procedure from a user equipment.

In S2, the method comprises providing an indication of the determined waveform to a base station from the user equipment.

Figure 9 shows a flowchart of a method according to an example embodiment. The method may be performed at a base station, e.g., a gNB.

In Ti, the method comprises receiving, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.

The gNB may determine the waveform to be used based on the indication.

The waveform may be one of a CP-OFDM waveform and a DFT-s-OFDM waveform.

The waveform may be used for transmission of PUSCH. The message may be MsgA (e.g., MsgA PUSCH) of a 2-step random access procedure or Msg3 of a 4-step RACH procedure. When the message is Msg3 of a 4-step random access procedure, the method may comprise providing the indication using Msg1 of the 4-step random access procedure.

The indication may be provided using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal (DMRS) for PUSCH, a message preamble or a RACH occasion associated with the determined waveform. DMRS for PUSCH may comprise at least one of the following: DMRS resources, DMRS sequence, DMRS cyclic shift or orthogonal cover codes (OCC).

In an example embodiment, for a 2-step random-access procedure, a UE may signal the waveform it uses for a MsgA PUSCH transmission using a corresponding PUSCH occasion, DMRS for PUSCH (e.g., DMRS resources, DMRS sequence, DMRS cyclic shift or orthogonal cover codes), MsgA preamble, and/or RACH occasion used for the MsgA transmission.

The message preamble would be MsgA's preamble in the case of a two step random-access procedure. In the case of a four step random-access procedure, the message preamble would be Msg 1 (which can be considered to comprise a preamble only).

The method may comprise receiving a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS (e.g., DMRS resources, DMRS sequence, DMRS cyclic shift or orthogonal cover codes), message preamble or RACH occasion at the user equipment from the base station. The configuration may be provided e.g., via (dedicated and/or common) message (MsgA or Msg3) configuration.

In an example embodiment, the UE is configured with at least one of the following to be corresponding or associated to a waveform (e.g., CP-OFDM or DFT-S-OFDM): MsgA PUSCH occasions, DMRS for MsgA PUSCH, MsgA preambles or MsgA RACH occasions.

The method may comprise determining the waveform based on a threshold. The threshold may comprise measurement criteria. Measurement criteria may include pathloss measurement (e.g., reference signal received power (RSRP)). In other words, the UE may select the used waveform based on pathloss measurement (e.g., RSRP) criteria or any other measurement criteria the UE may be able to perform.

Waveform selection by the UE may be based on a configured threshold (e.g., RSRP threshold). Specifically, if the RSRP measurement is below this threshold, the UE may select DFT-S-OFDM; otherwise, the UE may select CP-OFDM.

The threshold may comprise a number of preamble transmissions. In an example embodiment, the configured threshold is a maximum number of MsgA preamble transmissions performed before switching to a given waveform. For instance, UE may switch from CP-OFDM to DFT-S-OFDM after a maximum number of MsgA preamble transmissions has been reached.

The configured threshold may be used to select an SSB (and/or RACH resources) by the UE.

Such a threshold may be introduced e.g. in the IE RACH-ConfigComraonTwoStepRA-r16.

The method may comprise providing the indication of the determined waveform using UCI. The indication of the selected waveform may be carried using UCI on MsgA's PUSCH. MsgA comprises a plurality of PUSCH occasions/transmissions and the method may comprise causing the first PUSCH of the plurality of PUSCH occasions to be transmitted with a default waveform and the remainder of the plurality of the PUSCH occasions/transmissions to be transmitted with the selected waveform. In this case, more than one MsgA's PUSCH may be transmitted where the first PUSCH (e.g., the first in time or in frequency allocation) may carry the UCI indication on the selected waveform and this PUSCH may be transmitted with a default waveform (either CP-OFDM or DFT-S-OFDM). The selected waveform may then be applied to the remaining MsgA's PUSCHs.

In an example embodiment, where the message is MsgA of a 2-step RACH procedure, the gNB provides the UE with a configuration on the association (or mapping) between at least one of the following to a waveform (e.g., CP-OFDM, DFT-S-OFDM): PUSCH occasion, DMRS for PUSCH, MsgA preamble or RACH occasion. Hence, PUSCH occasions, DMRSs for PUSCH, MsgA preambles, and/or RACH occasions may be associated to different waveforms.

In other words, PUSCH occasion may be associated with a waveform, DMRS for PUSCH may be associated with a waveform (more specifically DMRS (time and/or frequency) resources, DMRS sequence, DMRS cyclic shift, and/or DMRS OCC (orthogonal cover code), may be associated with a waveform), MsgA preamble (index) may be associated with a waveform or RACH occasion may be associated with a waveform.

After the UE receives this configuration, the UE selects a waveform for each of its MsgA's PUSCH transmissions and the UE may use, for the MsgA transmission, at least one of the following in order to indicate the selected waveform to the gNB: PUSCH occasion corresponding to or associated with the selected waveform, DM RS for PUSCH corresponding to or associated with the selected waveform (more specifically, DM RS (time and/or frequency) resources, DMRS sequence, DM RS cyclic shift, and/or OCC, corresponding to or associated with the selected waveform), MsgA preamble (index) corresponding to or associated with the selected waveform or RACH occasion corresponding to or associated with the selected waveform.

The gNB may determine the determined waveform based on the indication.The gNB is thus aware of the waveform the UE applied to the msgA's PUSCH, and this information is used in order to (correctly) receive this PUSCH.

MsgA's PUSCH may be with repetition, in which case the selected waveform is applied to all PUSCH repetitions.

MsgA PUSCH retransmission may be performed considering the selected waveform by the 10 UE The method described with reference to Figures 8 and 9 may be applied in the 2-step or 4-step RACH procedure. In the 4-step RACH procedure, Msg1 (preamble index and/or RACH occasion) may be used to carry an indication of preferred waveform for the UE. This waveform may then be used by the UE for Msg3 transmission. In response to providing the indication, the method may comprise receiving information at the user equipment from the base station comprising an indication from the base station to change or confirm the determined waveform. For example, the gNB may confirm or change or keep the selected waveform through indication to the UE using Msg2 (via downlink control information (DOD/physical downlink control channel (POOCH) or Medium Access Control Control Element (MAC CE)).

Figure 10 shows a signalling flow between a gNB and a UE according to an example embodiment for a 2-step RACH procedure.

At 1001, a gNB provides the UE with a configuration of the association (or mapping) between PUSCH occasions, DMRSs for PUSCH, MsgA preambles and/or RACH occasions to different waveforms.

At 1002, the UE selects the waveform for UL transmission.

At 1003, the UE selects a PUSCH occasion, DMRS for PUSCH, MsgA preamble and/or RACH occasion, corresponding to the selected waveform for transmission of MsgA and applies the selected waveform to MsgA PUSCH.

At 1004, the UE causes MsgA transmission (preamble and PUSCH) corresponding to the selected waveform.

At 1005, the gNB determines the waveform used for MsgA PUSCH based on the MsgA transmission.

The waveform of PUSCH may be associated to several information elements (l Es). For this purpose, new information elements can be introduced. Then association of the waveform may be handled in several ways: Specific waveform (CP-OFDM or DFT-S-OFDM), for each instance of IF may be specified or configured. The waveform for each instance may follow the configuration for MsgA PUSCH.

The waveform for the new instance may be the other of the waveform signalled in existing RRC configuration for MsgA PUSCH.

A part of RRC configuration for 2-step random access according to 3GPP standards is discussed below. All these parameters are not mandatory in all cases, only if parameters used e.g. for initial BWP or common RACH parameters (common with 4-step RACH) are desired to be changed. However, parameters itself are similar in all these cases they are just part of different information elements (1E).

Both RACH and MsgA PUSCH related parameters are collected to MsgA-ConfigCommon-r16 IE. In MsgA-configcommon-r16 the waveform signalling could be done e.g. by having another instance of rach-Conf igCommonTwoStepRA, where the UE requests waveform by choosing corresponding RACH config and transmitting RACH accordingly and/or msgAPUSCH-Config where the UE requests waveform by choosing corresponding PUSCH config and transmitting PUSCH accordingly. In this case, the PUSCH configuration contains a parameter for transform precoding, which may be set accordingly.

These two options may or may not be used together RACH related parameters are found in RACH-ConfigCommonTwoStepRA-r16.

RACH configuration (PRACH configuration indices, frequency domain parameters etc) is defined by rach-ConfigGenericTwoStepRA-r16. This is needed if RACH occasions are not shared between 2-step and 4-step RACH.

In RACH-ConfigCommonTwoStepRA-r16 the waveform signalling could be done.

There are two possible cases for RACH. In the case where RACH occasions are shared between 2-step and 4-step RACH, another instance of parameter msgA-CBPreamblesPerSSB-PerSharedRO may be introduced to reserve preambles for the other waveform.

In the case where RACH occasions are not shared between 2-step and 4-step RACH, the case waveform may be associated to either RACH preamble or root sequence. The preamble may have instances of following parameters: msgA-SSB-PerRACH-OccasionAndCBPreamblesPerSSB which defines number of contention based preambles per SSB. SSB-PerRACH-Occasion may be re-used from existing parameter, hence there is only need for new parameter msgA-CB-PreamblesPerSSB-AlternativeWaveform-r18. msgATotalNumber0fRA-Preambles defines total number of preambles for 2-step RACH PUSCH configuration for MsgA may be given in MsgA-PUSCH-Config-r16. The configuration contains parameter for transform precoding; if parameter is enabled the waveform is DFT-S-OFDM, if disabled the waveform is CP-OFDM.

In MsgA-PUSCH-Config-r16 the waveform could be associated to at least another DMRS configuration or another DMRS scrambling ID. In both cases, the UE uses corresponding associated parameter for DMRS transmission and the gNB detects which one was used.

A method as described with reference to Figures 8 to 10 may allow dynamic waveform selection/switching by the UE for RACH procedures (e.g., 2-step RACH procedures). This is important to dynamically adapt to a suitable waveform for UL transmissions (such as PUSCH) of the RACH procedures.

An apparatus may comprise means for performing a method as described with reference to Figure 8 or a method as described with reference to Figure 9.

An apparatus may comprise means for determining a waveform to be used for transmitting a message of a random access procedure from a user equipment and providing an indication of the determined waveform to a base station from the user equipment.

Alternatively, or in addition, an apparatus may comprise means for receiving, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

It is noted that whilst some embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

As used herein, "at least one of the following: <a list of two or more elements>" and "at least one of <a list of two or more elements>" and similar wording, where the list of two or more elements are joined by "and" or "or", mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation." This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

The embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media. The term "non-transitory," as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process.

Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The scope of protection sought for various embodiments of the disclosure is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the disclosure.

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this disclosure will still fall within the scope of this invention as defined in the appended claims. Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

Claims 2. 3. 4. 5. 6. 7.
An apparatus comprising means for: determining a waveform to be used for transmitting a message of a random access procedure from a user equipment; and providing an indication of the determined waveform to a base station from the user equipment.
An apparatus according to claim 1, comprising means for providing the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, DMRS, for PUSCH, a message preamble or a random access channel, RACH, occasion associated with the determined waveform.
An apparatus according to claim 2, comprising means for receiving a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion from the base station An apparatus according to claim 2 or claim 3, wherein the DMRS for PUSCH comprises at least one of the following: DMRS resources, DM RS sequence, DMRS cyclic shift or orthogonal cover codes.
An apparatus according to claim 1, comprising means for providing the indication using uplink control information.
An apparatus according to any of claims 1 to 5, wherein the message is MsgA of a 2-step random access procedure.
An apparatus according to claim 6 when dependent on claim 5, wherein MsgA comprises a plurality of PUSCH occasions and comprising means for causing the first PUSCH of the plurality of PUSCH occasions to be transmitted with a default waveform and the remainder of the plurality of the PUSCH occasions to be transmitted with the determined waveform.
8. An apparatus according to any of claims 1 to 5, wherein the message is Msg3 of a 4-step RACH procedure and comprising means for providing the indication using Msg1 of the 4-step random access procedure.
9. An apparatus according to claim 8, comprising means for, in response to providing the indication, receiving information comprising an indication from the base station to change or confirm the determined waveform.
10. An apparatus according to any of claims 1 to 9, comprising means for determining the waveform from one of a cyclic prefix orthogonal frequency division multiplexing, CP-OFDM, waveform, and a discrete Fourier transform spread orthogonal frequency division multiplexing, DFT-s-OFDM, waveform.
11. An apparatus according to any of claims 1 to 10, comprising means for determining the waveform based on a threshold.
12. An apparatus according to claim 11, wherein the threshold is a measurement criteria threshold
13. An apparatus according to claim 12, wherein the measurement criteria comprise a pathloss measurement.
14. An apparatus according to claim 11, wherein the threshold comprises a number of preamble transmissions.
15. An apparatus comprising means for: receiving, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.
16. An apparatus according to claim 15, comprising means for receiving the indication using at least one of the following: a physical uplink shared channel, PUSCH, occasion, demodulation reference signal, DMRS, for PUSCH, a message preamble or random access channel, RACH, occasion associated with the determined waveform.
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25.An apparatus according to claim 16, comprising means for providing a configuration of the association between the waveform and the at least one of the following: PUSCH occasion, DMRS for PUSCH, message preamble or RACH occasion to the user equipment.An apparatus according to claim 16 or claim 17, wherein the DMRS for PUSCH comprises at least one of the following: DM RS resources, DM RS sequence, DMRS cyclic shift or orthogonal cover codes.An apparatus according to claim 15, comprising means for receiving the indication using uplink control information.An apparatus according to any of claims 15 to 19, wherein the waveform is one of a cyclic prefix orthogonal frequency division multiplexing, CP-OFDM, waveform, and a discrete Fourier transform spread orthogonal frequency division multiplexing, DFT-s-OF DM, waveform.An apparatus according to any of claims 15 to 20, wherein the message is MsgA of a 2-step random access procedure.An apparatus according to any of claims 15 to 20, wherein the message is Msg3 of a 4-step RACH procedure and comprising means for receiving the indication using Msg1 of the 4-step random access procedure.An apparatus according to claim 22, comprising means for, in response to receiving the indication, providing an indication from the base station to change or confirm the determined waveform.A method comprising: determining a waveform to be used for transmitting a message of a random access procedure from a user equipment; and providing an indication of the determined waveform to a base station from the user equipment.A method comprising: receiving, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.
26. An apparatus comprising: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: determine a waveform to be used for transmitting a message of a random access procedure from a user equipment; and provide an indication of the determined waveform to a base station from the user equipment.
27. An apparatus comprising: at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.
28. A computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: determining a waveform to be used for transmitting a message of a random access procedure from a user equipment; and providing an indication of the determined waveform to a base station from the user equipment.
29. A computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, from a user equipment at a base station, an indication of a determined waveform to be used for transmitting a message of a random access procedure from the user equipment.