Sidelink Positioning in Unlicensed Bands

Abstract

A method (40) for a first wireless node (UE1), comprising: transmitting (41) from the first wireless node (UE1) a sidelink position reference signal configuration (SPRS configuration 72, 83) defining at least one position reference signal to be transmitted from the first wireless node (UE1) to a second wireless node (UE2); generating (42) at least one position reference signal defined by the SPRS configuration to be transmitted to the second wireless node (UE2); conducting channel contention (43) for the purpose of transmitting a position reference signal within a bandwidth range at least partially comprised in an unlicensed radio band (F2), the contention being conducted using a listen-before-talk mechanism; and based on a positive result of the channel contention, accessing a channel for a duration of a channel on-time (44); and transmitting (45) the at least one position reference signal to the second wireless node (UE2) during the channel on-time.

Description

[Technical field]

[0001] The present specification relates to a first wireless node method, a second wireless node associated method, and related apparatus, systems, computer program elements, and non-transitory computer readable media for sidelink position determination using unlicensed bands. [Background technology]

[0002] Connected mobility is the subject of various communication standards such as IEEE 802.11p / bd and 3GPP® LTE / NR V2X (herein shortened as “V2X”). Two scenarios are considered for V2X, where a user equipment (UE) may be within or out of range of a base station (BS), such as an evolved node BS (eNB) or a 5G-NR node BS (gNB). Another scenario is that some of the co-connected UEs can be connected to the network, and the remaining co-connected UEs may be out of network coverage. This is called partial out-of-coverage.

[0003] Typically, when a UE (e.g., a UE mounted in a vehicle) is in coverage, the UE may be configured for sidelink communication with other UEs within range. In this case, resource allocation, data control, and communication procedures are controlled by the UE. When the UE is out of coverage, e.g., of a EUTRA or 5G-NR cell, the UE is preconfigured in a mandatory configuration for autonomous communication using sidelink. In an example, the UE may be preconfigured with some out-of-coverage frequencies. As an example, the out-of-coverage frequencies may include Intelligent Transportation System (ITS) frequencies.

[0004] Figure 1 illustrates diagrammatically an example of a wireless network 8. In this example, the network comprises a sidelink in a "V2X" configuration utilizing Modes 1 and 2, but it will be appreciated that the scenario of Figure 1 can be extended to other wireless standards with sidelinks between out-of-coverage wireless nodes.

[0005] Region 10 is outside the network coverage provided by the BS. Region 12 is an area of ​​partial coverage. Region 14 is in coverage. UE1 is a wireless node that communicates with UE2, for example, over a sidelink channel in mode 2. UE3 communicates from the area of ​​partial coverage to out-of-coverage UE4 over a sidelink channel in mode 2. UE5 communicates with UE6 over a sidelink channel in mode 1 as configured by control information Uu from the BS.

[0006] Identifying the location of a wireless node relative to another wireless node is of interest in many scenarios. Wireless standards such as 3GPP Release 16 allow a UE to be configured with a downlink Position Reference Signal (PRS) that has a high Resource Element (RE) density suitable for position determination calculations. A pattern of PRS is called a comb and is usually defined by the distance between two PRS REs and an offset over time. However, position determination techniques in 3GPP mobility scenarios can be further improved. Summary of the Invention

[0007] According to a first aspect, there is provided a method for a first wireless node, the method comprising: transmitting, from a first wireless node, a sidelink position reference signal configuration defining at least one position reference signal to be transmitted from the first wireless node to a second wireless node; generating at least one position reference signal defined by an SPRS configuration to be transmitted to a second wireless node; conducting channel contention for a location reference signal transmission within a bandwidth range that is at least partially contained within an unlicensed radio band, the contention being conducted using a listen-before-talk mechanism; accessing the channel for a duration of the channel on-time based on a positive result of the channel contention; transmitting at least one location reference signal to a second wireless node during the channel on time; Includes.

[0008] An effect is that position determination can be performed through the sidelink by transmitting sidelink position reference signals in the unlicensed carrier bands. This leads to improved location resolution since the sidelink position reference signal comb is detected and decoded with improved location resolution when covering a wider bandwidth. The application of channel sensing allows improved location resolution to be achieved without interference with higher priority users of the unlicensed bands. This allows many regulatory requirements that require access to the unlicensed spectrum to be maintained (such as nominal bandwidth and adjacent nominal carrier aggregation by the same device). The techniques detailed herein are flexible and can be applied to different nominal bandwidths and different nominal aggregated bands as specified between different regions. For example, the ETSI BRAN regulations mandate a nominal frequency of 20 MHz and aggregation bands of 4, 8, 16, etc. in the 5 GHz and 6 GHz frequency bands, but the techniques discussed herein can be generalized to other regions.

[0009] In other words, the first problem addressed is that rotation is limited to dedicated (ITS) and licensed bands, where unlicensed bands may be used to interpolate the ITS / licensed bands.

[0010] A second problem is that it is difficult to guarantee a wideband carrier for sidelink positioning simultaneously with the communication carrier. In this case, unlicensed wideband operation can be used to increase the available bandwidth, which is important for enhancing positioning accuracy.

[0011] The third problem is initiating channel on time (COT) and sharing channel on time (COT). According to this specification, when a sidelink position reference signal (SPRS) is scheduled, a wireless node shares its channel on time with other wireless nodes to send out the SPRS, and the other wireless nodes use the transmission opportunity with a short time gap to avoid losing the channel contention. If the channel contention of the first wireless node fails, the second wireless node will not detect the SPRS of the first wireless node.

[0012] According to a second aspect, there is provided a method for a second wireless node, the method comprising: transmitting to the first wireless node a sidelink position reference signal configuration defining at least one position reference signal to be transmitted from the first wireless node to a second wireless node; receiving at least one sidelink position reference signal transmitted by the first wireless node within a bandwidth range that is at least partially comprised in an unlicensed radio band, the at least one sidelink position reference signal being defined by a sidelink position reference signal configuration; Includes.

[0013] According to a third aspect, a first wireless node is provided, the first wireless node comprising a wireless modem, a non-transitory computer readable medium with machine readable instructions, and a processor configured to load and execute the machine readable instructions to cause the first wireless node to perform a method according to the first aspect or an embodiment thereof and thereby to transmit a modified position reference signal over at least one sidelink channel to a second wireless node.

[0014] According to a fourth aspect, there is provided a second wireless node, the second wireless node comprising a wireless modem, a non-transitory computer readable medium with machine readable instructions, and a processor configured to load and execute the machine readable instructions to cause the second wireless node to perform a method according to the second aspect or an embodiment thereof.

[0015] According to a fifth aspect there is provided a system for wireless communication comprising a first radio node as defined by the third aspect and a second radio node as defined by the fourth aspect.

[0016] According to a sixth aspect there is provided a computer program element comprising machine readable instructions which, when loaded and executed by a processor, causes the processor to perform a method according to the first aspect.

[0017] According to a seventh aspect there is provided a computer program element comprising machine readable instructions which, when loaded and executed by a processor, causes the processor to perform a method according to the second aspect.

[0018] According to an eighth aspect, there is provided a non-transitory computer readable medium comprising machine readable instructions of the sixth or seventh aspects. According to a ninth aspect, there is provided a vehicle comprising a wireless communication node according to one of the third or fourth aspects.

[0019] This specification therefore proposes two general techniques for accessing unlicensed frequency bands for sidelink position determination. The first technique uses licensed (ITS) or dedicated carrier assisted access, where a licensed or dedicated carrier is used on the sidelink to control the transmission of position determination signals on the unlicensed spectrum. A dedicated carrier may also be used to send broadcast information. A further technique is discussed in which both control and position determination signals are sent on the unlicensed spectrum without the need for licensed (ITS) or dedicated carrier assisted access.

[0020] Exemplary embodiments of the invention are illustrated in the drawings, which should not be construed as limiting the scope of the claims, and are described in more detail below. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 illustrates a schematic diagram of an example of a “V2X” configured system with a sidelink that can be configured for mode 1 and mode 2. [Diagram 2] FIG. 13 illustrates an example of a sidelink time and frequency resource configuration for mode 2; [Diagram 3] FIG. 1 illustrates a schematic diagram of sidelink position reference signal (SPRS) resources from the perspective of an RX UE. [Figure 4a] FIG. 2 illustrates a schematic diagram of a method for a first wireless node according to a first aspect. [Figure 4b] FIG. 13 illustrates a schematic diagram of a method for a second wireless node according to a second aspect. [Diagram 5] FIG. 2 illustrates a schematic diagram of a first example of establishing an SPRS exchange on an unlicensed carrier. [Figure 6] FIG. 2 illustrates a schematic diagram of a signaling protocol for establishing an SPRS exchange on an unlicensed carrier using control signals sent on a licensed carrier. [Figure 7] FIG. 2 illustrates a schematic diagram of a second example of establishing an SPRS exchange on an unlicensed carrier. [Figure 8] FIG. 13 is a schematic diagram illustrating a third example of establishing an SPRS exchange on an unlicensed carrier. [Figure 9] A diagram illustrating a fourth example of establishing an SPRS exchange on an unlicensed carrier. [Figure 10] FIG. 13 illustrates generally another example of a signaling protocol for establishing an SPRS exchange on an unlicensed carrier using control signals sent on the unlicensed carrier; [Figure 11] FIG. 2 is a schematic diagram illustrating an example of a SPRS format definition. [Figure 12] 2A-2C are schematic diagrams illustrating examples of wireless nodes according to the third and / or fourth aspects; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] FIG. 1 illustrates generally an example of a V2X-configured system with a sidelink that may be configured for mode 1 and mode 2. The wireless standard 5G New Radio (5GNR) provides a network with a next generation node base station (gNB) and a set of user equipment (UE1, UE2, ...). The gNB is used for controlling the communication of data to some or all of the UEs through a Uu interface. The Uu interface may be considered to be a communication link between the gNB and another network terminal UE. In an example, the UE terminal (also referred to herein as a wireless node) may be an IoT device, a vehicular infrastructure element, an industrial automation component, or an industrial infrastructure element. Examples of vehicular infrastructure elements are traffic lights and street lights. Examples of industrial infrastructure elements are robots or industrial machines. The UE terminal may be a mobile phone, a laptop computer, a tablet, a smart watch, etc. The UE terminal may be embodied in a vehicle such as an automobile, a heavy goods vehicle, a bicycle, etc.

[0023] The 3GPP standard provides for the transmission of signals between a first and a second radio node, which may, for example, enable the second radio node to determine its position relative to the first radio node. The signals are usually called "combs" because of their structure in frequency and time. The first radio node UE1 may be requested by the second radio node UE2 to transmit a position reference signal (PRS) having a comb structure known at the second radio node UE2. When the second radio node UE2 receives the requested PRS from the first radio node, decoding techniques such as Downlink Angle of Radiation (DL-AoD), Uplink Angle of Incidence (UL-AoA), Round Trip Time (RTT), Downlink Time of Arrival (DL-ToA) or Uplink Time of Arrival (UL-ToA) may be applied by the second radio node UE2 to the PRS transmitted by the first radio node UE1. This enables the second radio node UE2 to determine its position relative to the first radio node UE1.

[0024] Current implementations of positioning using PRS only support positioning for classical cellular scenarios, such as positioning between a gNB (base station, BS) and a mobile radio node (UE). Vehicular and industrial applications require gNB-independent UE-to-UE positioning when out of (or in partial) gNB coverage. Current specifications detail approaches for using PC5 sidelinks to assist radio node-to-radio node positioning.

[0025] FIG. 2 illustrates an example of a time and frequency resource configuration for the sidelink in Mode 2. The sidelink resource allocation 16 in Mode 2 is divided into frequency resource blocks (range of subchannels) FRE and time slots TRE. In one example, a subset 17 of the sidelink resource allocation in Mode 2 is configured by the gNB. Another subset 15 of the resource allocation is dedicated for autonomously used resources accessed by the radio node UE. In one example, one or more UEs may use semi-periodic scheduling of the sidelink resource allocation 16 to compete for sidelink resources. In Mode 2, resources may be allocated as one-shot transmissions and the UE transmits in resources controlled by the gNB or in autonomously allocated resources as MAC-PDUs as available. In another example, the configured sidelink resources may enable the UE to transmit multiple MAC-PDUs in multiple transmission opportunities.

[0026] 3GPP Release 16 proposes a position reference signal configuration that defines the structure of PRS signals during the downlink and / or uplink between the UE and the gNB (BS), for example. The position reference signal configuration also defines on which OFDM symbols and subcarriers the PRS can be found. A PRS positioning frequency layer is defined as a collection of PRS resource sets, where each PRS resource set defines a set of PRS resources. When applied to localization between a wireless node, such as a gNB, and an item of user equipment, such as UE5, one or more downlink position reference signals are transmitted from the gNB (BS) and used at the UE5. The 3GPP Release 16 PRS has a diagonal or staggered PRS pattern and a high resource element density with better correlation properties than existing reference signals.

[0027] The improved PRS signals of 3GPP Release 16 cannot be mapped to the problem of position determination between the first and second radio nodes UE1, UE2 over the sidelink in mode 2. In base station (gNB) coordinated position determination, the base station can coordinate which comb pattern from the PRS set, with which offset, is used by the base station and the associated UE. This prevents a given UE from experiencing collisions of two different PRSs at the same time. However, applying the PRS directly to position determination between the first UE1 and the second radio node UE2 using a sidelink resource pool is problematic because resource selection in the sidelink resource pool is usually done autonomously between at least two UEs using a distributed contention protocol such as semi-persistent scheduling. Thus, at least two UEs can choose the same offset to transmit the same PRS pattern, for example. This results in the allocation of overlapping PRS resources. Thus, the sidelink PRS cannot be resolved between UE1 and UE2, degrading position determination performance.

[0028] Furthermore, the PRS comb structure defines the spacing of the PRS for different users, which defines how many users can share one PRS block. Thus, there is a tradeoff between the number of users involved in position determination with several PRS patterns using the same sidelink resource pool, and the performance of the ranging itself.

[0029] FIG. 3 illustrates a schematic of sidelink position reference signal (SPRS) conflicting resources from the perspective of a RX UE. In Fig. 3, region 20 is a time-frequency plot representing a portion of the resource grid of the sidelink resource pool from the RX point of view of the first radio node UE1. Along the frequency axis 23 the subchannel index is shown and along the time axis 22 the time (slot) index is shown. OFDM slots of multiplexed SPRS from the three radio nodes UE1, UE2 and UE3 are shown. Regions 21a and 21b of the sidelink resource pool are areas with data symbols (not used for position determination), gaps or blank symbols. For example, regions 21a and 21b are regions of licensed bandwidth and region 21c represents a region of unlicensed bandwidth for transmission of SPRS according to the techniques discussed later. The shaded symbols 24 represent colliding SPRS.

[0030] The techniques of this specification are applicable to radio nodes defined according to 3GPP REL-16 NR for unlicensed access, such as in RP-201834. In one embodiment, the first and second radio nodes comply with Scenario A: Carrier aggregation between licensed band NR (PCell) and NR-U (SCell). In one embodiment, the first and second radio nodes comply with Scenario B (dual connectivity between licensed band (PCell) and NR-U (PSCell)). In one embodiment, the first and second radio nodes comply with Scenario C (Standalone NR-U). In one embodiment, the first and second radio nodes comply with Scenario D (Standalone NR cell in unlicensed band and UL in licensed band). In one embodiment, the first and second radio nodes comply with Scenario E (dual connectivity between licensed band NR and NR-U).

[0031] In LTE, licensed assisted access for the downlink was introduced early with “listen before talk” (LBT) to avoid collisions with existing transmissions in unlicensed bands. Enhanced Licensed Assisted Access (eLAA) introduced LBT on the uplink. 5G New Radio introduces unlicensed operation for both uplink (UL) and downlink (DL) in licensed or unlicensed coverage. In this case, a radio node such as a UE or gNB starts LBT channel sensing to discover nearby interference. After winning the LBT, the gNB or UE starts Channel Occupancy Time (COT). COT depends on many factors such as how often the LBT is false, the number of HARQ NACKS, etc. During COT, the UE or gNB transmits their UL or DL ​​simultaneously.

[0032] For unlicensed operation, NR introduces two approaches for channel sharing based on the need of supported traffic: load-based event LBE and frame-based event FBE COT. In LBE, the UE or gNB accesses the channel after a successful LBT when there is data to be transmitted in the uplink or downlink. In this case, the radio node can only start the LBT just before the pre-scheduled UL grant can occupy the scheduled time slot. In the seizure and grant procedures, which do not differ greatly, FBE does the LBT in a time-deterministic manner, but the COT is shared with other devices to send feedback or return traffic.

[0033] The COT sharing between uplink and downlink must guarantee a short time gap between traffic direction switching between a first device (initiating the COT) and a second device (sharing the same COT), such as 16 μs or less. After such a gap, the second device is expected to share the COT and send the opposite traffic after a short sensing interval (LBT-CAT2) or no sensing (LBT-CAT4). However, if a short LBT is mandated, the second device refrains from transmitting if the LBT result is negative.

[0034] FIG. 4a illustrates diagrammatically a method for a first radio node according to a first aspect. According to a first aspect, a method 40 for a first radio node UE1 is provided, the method 40 comprising: - a step 41 of transmitting from the first radio node UE1 a sidelink position reference signal configuration 72, 83 defining at least one position reference signal to be transmitted from the first radio node UE1 to the second radio node UE2; a step 42 of generating at least one position reference signal defined by an SPRS configuration to be transmitted to the second radio node UE2; a step 43 of performing channel contention LBT for a location reference signal transmission within a bandwidth range that is at least partially included in the unlicensed radio band F2, the contention being performed using a listen-before-talk mechanism; a step 44 of accessing the channel for the duration of the channel on-time based on a positive result of the channel contention; a step 45 of transmitting at least one location reference signal to the second wireless node UE2 during the channel on-time; Includes.

[0035] The techniques of the first aspect are directed to two approaches to enabling access to unlicensed bands for SPRS purposes. First approach: Licensed / ITS / dedicated carrier-assisted access to unlicensed bands The first approach handles data transmission and reception in the licensed band F1 and transmission of a sidelink ranging pilot transmission SPRS in the unlicensed band F2. In one embodiment, the first wireless node uses a first channel contention technique to perform channel contention on the licensed carrier F1. In one embodiment, the unlicensed carrier F2 assists in channel contention using another channel access mechanism, such as LBT, clear channel assessment CCA, or monitoring of the channel occupation time COT.

[0036] In one embodiment where the associated channel access mechanism monitors the COT, channel access may be arranged as a frame-based event or a load-based event. According to the first approach, the licensed band F1 carries information and configuration commands for SPRS symbols intended to be transmitted, for example, from the first radio node UE1 to the second radio node UE2 (such as the interlace pattern and slot or transmission schedule of the SPRS). Thus, the first radio node may perform an SPRS configuration transmission 72, 83 according to regulatory requirements (such as LBT, CCA, COT decision) before the transmission of the SPRS itself in the unlicensed band F2. In one embodiment, the receiving radio node can decode the information received in the licensed carrier F1 regarding the sidelink positioning configuration (interlace pattern, slot and / or transmission schedule of the SPRS) in the unlicensed band F2. The second radio node obtains the information received in the licensed carrier F1 to assist the second radio node to coordinate with the sidelink positioning transmission opportunity TO.

[0037] In a first approach, the optional mode is completely optional (embodiment shown in FIG. 5). In this embodiment, the first radio node UE1, or group of radio nodes UE-G1, may signal an intention to schedule one SPRS pattern configuration (e.g., one SPRS pattern out of a total of N possible patterns enabled by the concerned interlace) in a certain synchronized sidelink slot SL TX. In this embodiment, the first radio node UE1, or group of radio nodes UE-G1, is configured to sense the unlicensed carrier F2 for free channel access using a channel contention mechanism and to send at least one SPRS without any obligation for short control or physical control information. The assumption is that all necessary control information has been conveyed through signaling on carrier 1.

[0038] A quasi-asynchronous variant of the previous example may proceed from unicast or groupcast of sidelink communications on synchronized and licensed carrier F1. In one embodiment, the first radio node UE1 may select its SPRS location in time and frequency based on pre-configuration or dynamic network configuration. In one embodiment, the first radio node UE1 initiates channel contention, such as LBT, to evaluate the availability of free SPRS transmission opportunities. The first radio node UE1 sends out an SPRS signal or pattern to cover a predefined percentage of the nominal frequency. For a group of radio nodes UE, each radio node may select a different SPRS format definition (interlace pattern) to use within the same percentage of the nominal frequency such that transmissions by the SPRS group of UEs multiplex themselves on the same resources. In one embodiment, the interlace structure of the SPRS is chosen randomly by each radio node in the group of radio nodes to avoid collisions between SPRS patterns.

[0039] In one embodiment, a radio node, or a group of radio nodes, is configured with a possible set of SPRS format definitions (a set of interlace structures for SPRS) and a reservation procedure for each SPRS format definition within the SPRS format definition. The group of radio nodes is configured to select from the SPRS format definitions and reserve their respective selections in a reservation field. Each radio node then transmits this reservation by signaling to the other radio nodes through sidelink signaling. In one embodiment, one or more radio nodes in the group of radio nodes UE-G perform channel contention, e.g., using LBT, to evaluate the availability of a free SPRS transmission opportunity (SPRS-T1,...) schedule for this pattern. If free, the first radio node initiates an SPS transmission to block the free SPRS transmission schedule.

[0040] In one embodiment, the SPS may optionally be preceded by a preamble or short control information transmission. If other scheduled radio nodes can detect the initial transmission and decode the initial COT information signaled in the licensed band F1 or optionally preceding the SPRS in the short control information, the next scheduled radio node UE, or group of radio nodes UE-G, may share the channel occupation time, as long as the channel occupation time does not end.

[0041] Second approach: Standalone unlicensed band channel access In a second approach, a self-organizing channel access technique for sidelink position determination in the unlicensed band F2 is considered. In this approach, the unlicensed carrier F2 is used exclusively for sidelink position determination or the unlicensed carrier F2 is used for a combination of circular position determination and data communication. According to the second technique, synchronization through communication exchange on the licensed carrier F1 is not required. In one embodiment, the wireless node may synchronize with the unlicensed carrier F2 by sending out broadcast and / or synchronization information on the unlicensed carrier F2.

[0042] In one embodiment, synchronization on the unlicensed carrier F2 includes 3GPP synchronization techniques, such as sync to sync master / GNSS, sync to gNB (broadcasting synchronization signals in licensed or unlicensed bands), sync to sync source UE, etc. Synchronization signaling may be exchanged for the licensed carrier F1. In one embodiment, when only the unlicensed carrier F2 is available and no other synchronization sources are available, synchronization between wireless nodes may be performed through configuring a resource pool in mode 2 (but in the unlicensed bands) and exchanging synchronization sequences before participating in position determination.

[0043] According to the second approach, the SPRS is transmitted asynchronously. The first radio node UE1 or a group of radio nodes UE-G simultaneously perform a channel contention technique, e.g., LBT, and one or more of the radio nodes UE1 find the unlicensed band F2 free. In this case, the first radio node UE1 with the winning channel contention may assign one out of a total of N SPRS format definitions (interlace patterns) in frequency. In one embodiment, the SPRS format definition may be selected randomly. The selected pattern in time and frequency is used to transmit the short control and SPRS structure after a successful training contention. Other radio nodes can only receive the short control and / or SPRS transmissions or attempt to seize the channel to send out the SPRS and / or short control.

[0044] In one embodiment, channel occupancy time sharing of radio nodes that need to send FBE or LBE SPRS is performed. The first radio node UE1 or a group of asynchronous radio nodes UE-G senses the channel using an initial channel contention process. Based on the success of the channel contention process, the first radio node or a group of asynchronous radio nodes selects one of N SPRS format definitions (interlace patterns) and performs short control transmission and SPRS. Any other station (or group of stations) that senses the network and can decode possible short information (with COT duration) and SPRS can share the COT initially initiated by UE1 and also send their SPRS according to the SPRS format definition. Other radio nodes or groups of radio nodes may share the initiated initial channel occupancy time COT as long as the COT is sufficient for further SPRS and / or short control transmission. In the case of FBE, the initiated COT can send some information about the periodicity of the SPRS, i.e., the initial procedure is repeated before each period, as shown in FIG. 9 below.

[0045] According to one embodiment, the first radio node UE1 is configured to use a sidelink (such as a 5G NR sidelink) in a licensed band F1 (ITS or licensed carrier). According to one embodiment, the second radio node UE2 is configured to use the sidelink for sidelink positioning on an unlicensed carrier F2.

[0046] The first wireless node embodiment relates to the manner in which a transmission opportunity for the SPRS is provided such that the transmission opportunity is simultaneous with transmission and reception on another carrier. In addition, the embodiment specifies the behavior (such as listen-before-talk) of the first wireless node with respect to channel contention, if win or lose.

[0047] The following description discusses five options. Options 1, 2, and 3 relate to embodiments in which the licensed band F1 is dedicated to assisting position determination in the unlicensed band F2. In such a case, it is expected that the licensed or dedicated sidelink band F1 will be used to convey data and control signals to radio nodes in the immediate vicinity 10, 12, 14 of the first radio node UE1. It is also assumed that subsequent control signals on the licensed or dedicated band F1 carry configuration information regarding the unlicensed sidelink band F2 that is dedicated for position determination. Options 4 and 5 relate to unlicensed sidelink position determination embodiments that do not require communication in the licensed sidelink band F1.

[0048] Option 1: Pre-configuration FIG. 5 illustrates diagrammatically a first example of the establishment of an SPRS exchange on an unlicensed carrier. According to one embodiment, the method includes the steps of obtaining synchronization of at least one position reference signal for at least one transmission opportunity of a side channel from an SPRS arrangement 72, 83; If the channel contention LBT is positive for the purpose of transmitting a position reference signal during at least one transmission opportunity of the side channel, and transmitting at least one location reference signal to the second wireless node UE2 during the channel on-time.

[0049] According to one embodiment, at least the first UE1 and the second UE2 radio nodes are members of a 5G NR radio network. According to one embodiment, the licensed radio band F1 comprises a vehicle-to-vehicle / vehicle-to-infrastructure V2X sub-band of a 5G NR wireless network.

[0050] According to one embodiment, the unlicensed radio band F2 is included within at least one of the ranges: 5150-5925 MHz; 5150-5350 MHz (WAS / RLAN); 5470-5725 MHz (WAS / RLAN); 5725-5855 MHz (FWA); 5855-5875 MHz; 5875-5925 MHz (ITS), 5150-5250 (U-NII-1), 5250-5350 (U-NII-2A), 5350-5470 (U-NII-2B), 5470-5725 (U-NII-2C), 5725-5850 (U-NII-3), or 5850-5925 (U-NII-4).

[0051] According to an embodiment, the first UE1 and / or second UE2 radio node operates in a frame based equipment mode or a load based equipment mode. FIG. 5 is a time-frequency matrix showing channel events on licensed carrier F1 and unlicensed carrier F2 simultaneously. According to the first technique, data transmission and reception and / or control transmission and reception are handled in licensed carrier F1. Regions 70A, 70B define areas of unlicensed band F2 that are free of transmissions or contain other signals transmitted in unlicensed band F2 by other technologies such as Wi-Fi™ or other UE groups. SPRS-T1, SPRS-T2 correspond to potentially configurable SPRS transmission opportunities on unlicensed band F2. In licensed band F1, axis 61 defines the SL slot to which second radio node UE2 is synchronized in SYNC operation 71. For the purposes of this example, it is assumed that there is only one UE group in unlicensed band F2 with first radio node UE1 and second radio node UE2.

[0052] For example, in a first option, data and / or control, as well as limited configuration for SPRS, are communicated from the first radio node UE1 to the second radio node UE2 through the licensed band F1 (SL RX, SL TX). The unlicensed band F2 carries the SPRS according to a transmission opportunity TO that is positioned relative to a synchronization control signal received in the licensed band F1. According to the first option, no channel occupation time COT sharing is performed and the unlicensed band is used for LBE. In this option, the first and / or second radio nodes communicate in a load-based equipment mode LBE.

[0053] According to an embodiment of option 1, the licensed band carrying the sidelink F1 carries SPRS configurations 72, 83 for the SPRS (SLTX, SLRX) to be transmitted in the unlicensed band F2. For example, the licensed band carries possible SPRS signal formats that define the interlace pattern, the channel on-time, and the expected potential positioning opportunities. One or more of the signals may be referenced to a configured synchronization 80 of the carriers transmitted in the licensed band F1, including, for example, the slot configuration. When the first radio node UE1 accesses the unlicensed carrier UE2, the channel contention operation performed by the first radio node UE1 (e.g., LBT) should be started early enough to allow synchronized transmission of the SPRS on the unlicensed carrier UE2 in case of successful LBT.

[0054] If the channel contention in the unlicensed band F2 (LBT) is successful, the first radio node UE1 must send the SPRS within a possible Tx opportunity (e.g., SPRS-T1 in 70A). If the channel contention in the unlicensed band F2 (LBT) is not successful, the first radio node UE1 extends the channel contention window LBT-E (corresponding to clear channel assessment CCA) until the first radio node UE1 is successful in channel contention for the unlicensed carrier F2. The first radio node UE1 then transmits the SPRS without extending the possible SPRS window SPRS-T1. If the first radio node UE1 does not win the channel contention for the unlicensed carrier F2 before the possible SPRS transmission opportunity expires, the first radio node UE1 must cancel the SPRS transmission and configure a new opportunity SPRS-T2. In this case, the new opportunity is also an LBE-based transmission in the unlicensed band F2.

[0055] As shown in Fig. 5, a first group of radio nodes UE-G1 is optionally provided. When a radio node UE is transmitting an SPRS in this group, it may apply an interlace pattern to each SPRS that is orthogonal to the patterns of other radio nodes UE in the same group UE-G1. Thus, if two radio nodes select the same pattern, collisions can optionally be resolved using different orthogonal codes for each radio node.

[0056] FIG. 6 illustrates generally a signaling protocol for establishing an SPRS exchange on an unlicensed carrier using control signals sent on a licensed carrier. For example, Figure 6 shows a process of transferring signals between a first radio node UE1, a second radio node UE2, associated licensed band F1 and unlicensed band F2. Initially, the first radio node UE1 transmits a time synchronization 71 SYNC on the licensed band F1 to the second radio node UE2. The first radio node UE1 transmits an SPRS configuration 72 with control data and / or a first SPRS configuration message to the second radio node UE2. The first radio node UE1 performs channel contention 73, 74 on the unlicensed band F2, and if the channel contention is successful, the first radio node UE1 transmits an SPRS 75 to the second radio node UE2 within the SPRS-TO defined by the synchronization 71. The transmitted SPRS 75 corresponds to a previously signaled definition of the SPRS configuration. For example, the SPRS configuration may comprise a description of the SPRS comb to be transmitted in terms of occupied bandwidth, occupied slots, interlace definition, etc. The SPRS may be received by the second radio node UE2 and used to calculate the relative position of the first radio node UE1 relative to the second radio node UE2.

[0057] If the channel contention 74 is unsuccessful, the first radio node UE1 attempts a discontinuous number of further channel contention operations in the unlicensed band F2. In one embodiment, after an allowed time gap 77 relative to the channel on-time COT, which is initiated relative to the transmission of the first SPRS, the second radio node UE2 transmits 76 a further SPRS to the first radio node UE1. In one example, the SPRS 76 corresponds to a definition of a previously signaled SPRS configuration. In another example (not shown), the first radio node UE1 or the second radio node UE2 can be involved in signaling to negotiate a different SPRS configuration for the SPRS transmitted from UE2 to UE1. The response can be used by the first radio node UE1 to calculate its position relative to the second radio node UE2 according to techniques known to those skilled in the art, such as RTT.

[0058] According to one embodiment, the SPRS configuration 72, 83 is transmitted to the second radio node UE2 over a sidelink channel in the licensed radio band F1 of the radio access network. According to an embodiment, the SPRS configuration 72, 83 is transmitted by the first radio node UE1 over at least one of the Physical Sidelink Shared Channel PSSCH, the Physical Sidelink Control Channel PSCCH, the Physical Downlink Shared Channel PDSCH, the Physical Downlink Control Channel PDCCH or the Physical Sidelink Broadcast Channel PSBCH of the radio access network.

[0059] A variation of option 1 is now discussed as option 2. According to the second option, in which the SPRS transmission is quasi-asynchronous, the licensed band F1 carries data, control, and configuration of the SPRS when transmitted on the unlicensed band F2. The unlicensed band F2 carries the SPRS scheduled relative to the transmission opportunities defined in the synchrony of the licensed band F1. This can be applied to FBE or LBE type COT sharing.

[0060] FIG. 7 illustrates diagrammatically a second example of the establishment of an SPRS exchange on an unlicensed carrier according to the second option. According to one embodiment, the method comprises: - transmitting a periodicity specifier 80 to the second radio node UE2 defining a plurality of further position reference signal 76, 87 transmission opportunities of the first radio node UE1 and / or the plurality of further radio nodes relative to an initial position reference signal transmission opportunity SPRS-T1; performing, at the first radio node UE1, a plurality of further channel contention LBT operations corresponding to a respective one of a plurality of position reference signal transmission opportunities; accessing the channel for a duration of the channel on-time based on at least one positive outcome of the further channel contention operation; transmitting at least one further location reference signal 76, 87 to the second wireless node UE2 during a channel on-time defined by a periodicity specifier 80; Includes.

[0061] According to the second option 62, the first radio node UE1 configures the periodicity of its SPRS transmission in the unlicensed band F2. This corresponds to a frame-based equipment FBE mode on the unlicensed band F2. Thus, the further radio node may schedule the transmission of its further SPRS by utilizing the channel on-time COT signaled by the first radio node UE1. This may be referred to as COT sharing. In this case, the radio nodes in the group UE-G1 do not need to maintain a gap between their SPRS transmissions suitable for COT sharing. If the first radio node does not share its channel on-time COT in the licensed band F1, the other radio nodes in UE-G1 will not be able to share the channel on-time and may need to perform channel contention (LBT) for each transmission.

[0062] As shown in Fig. 7, a first radio node UE1 pre-configures or signals SPRS for multiple user groups UE-G1, UE-G2, UE-GK in a licensed band F1. In one example, an initial transmission for the SPRS in the first user group UE-G1 is scheduled in the unlicensed band F2 using LBT CAT-4 type channel contention for the initial transmission and LBT CAT-2 or CAT-1 / 0 for other SPRS group transmissions sharing the COT of the initial transmission. In general, in an embodiment, at least one radio node UE1 included in the first group of radio nodes UE-G1 performs an initial SPRS transmission in the unlicensed band F2 using a first type of channel contention, and a second group of radio nodes UE-G2 performs a subsequent SPRS transmission in the unlicensed band F2 using a second type of channel contention. In one embodiment, at least a first group of wireless nodes UE-G1 and a second group of wireless nodes UE-G2 share a channel on time initiated by a wireless node UE1 in the first group of wireless nodes UE-G1.

[0063] According to one embodiment, the method comprises: transmitting a schedule of transmission opportunities for further position reference signals 76, 87 of the first wireless node UE1 and / or the plurality of further wireless nodes to the second wireless node UE2; performing, at the first radio node UE1, a plurality of further channel contention LBT operations corresponding to a respective one of a plurality of position reference signal transmission opportunities; accessing the channel for a duration of the channel on-time based on at least one positive result of the further channel contention operation LBT; transmitting at least one further location reference signal 76, 87 to the second wireless node UE2 during a channel on-time defined in the schedule of further location reference signal transmission opportunities; Includes.

[0064] A variant of the second option, which will now be discussed as the third option, is also shown in Fig. 7. In this embodiment, the first radio node UE1 (or in other words the radio node that first performs channel contention on the unlicensed band F2) is configured to share its channel on-time COT within a period designated SPRS-T1, SPRS-T2, and to periodically configure active transmission instances with multiple radio nodes UE in one or more user groups UE-G1, UE-G2. Any other radio node UE can share the channel on-time, provided that the channel on-time has not expired and is not longer than the allowed gap remaining between one UE and the next UE. If a gap is unintentionally left between one radio node UE sharing a previously configured on-time, channel contention is mandated. Thus, option 3 is considered to be a synchronous S-mode, in which the licensed band F1 carries the expected configuration of data, control, and SPRS on the unlicensed band F2, and the unlicensed band F2 carries SPRS that is strictly scheduled for transmission opportunities as it may be more useful for the FBE mode.

[0065] According to one embodiment, the channel contention LBT performed by the first radio node UE1 for the purpose of location reference signal transmission is a category 4 listen-before-talk operation. According to one embodiment, the channel contention LBT performed by the first wireless node UE1 for further location reference signal 76, 87 transmission opportunities is a category 2 listen-before-talk operation.

[0066] A second approach option is next discussed, in which channel access for the SPRS is negotiated without using licensed bands. According to one embodiment, the SPRS configuration 72, 83 transmitted by the first radio node UE1 is received within the bandwidth range of the unlicensed radio band F2 during a channel on-time associated with a channel contention LBT for control signaling.

[0067] Fig. 8 shows a schematic diagram of a fourth option for the establishment of an SPRS exchange on an unlicensed carrier. This does not require the additional use of the licensed band F1. According to the fourth option, data transmission and SPRS transmission occur on the unlicensed band F2. Channel contention occurs every time a wireless node sends control and data, or control data and SPRS, or only short control information followed by SPRS. Every time there is a normal control or a short control, the first wireless node signals the configuration of the SPRS (duration, pattern, etc., and COT duration).

[0068] In Fig. 8, slots SL1, SL2 in the unlicensed band F2 indicate short control channels used to communicate transmission of SPRS from a first wireless node UE1. After transmission of the short control channel SL1, a corresponding SPRS is transmitted, where the transmission of the SPRS of a certain wireless node is not coordinated with other wireless nodes. The short control SL1, SL2 and SPRS are sent out only after channel contention (LBT). UE-A, UE-B indicate individual wireless nodes.

[0069] According to a third option 63, the first radio node UE1 may share its channel on-time in the unlicensed band F2 with other radio nodes and configure the SPRS periodically using control signals transmitted in the unlicensed band F2. In this embodiment, there is no dedicated transmission opportunity and the channel on-time between the radio nodes is shared. At least one other radio node UE may share the channel on-time COT of the first radio node UE1, provided that the channel on-time COT of the first radio node UE1 has not expired and a gap not longer than allowed is left between the transmission of the first radio node and the subsequent radio node. If a gap is left unintentionally between the radio node UE1 sharing the unlicensed band F2 and the subsequent radio node, channel contention occurs.

[0070] 9 shows a schematic diagram of a fifth option for the establishment of an SPRS exchange on an unlicensed carrier. According to the fifth option, both control and location signaling occur exclusively on the unlicensed band F2. An initial SPRS with channel contention (LBT) is performed, in other words an initial dedicated COT, after an initial transmission opportunity for the SPRS is detected by the wireless node.

[0071] For example, a group of multiple radio nodes UE-G1, UE-G2 to UE-GK perform groupcast communication and coordinated sidelink communication in the unlicensed band F2. In this case, the SPRS is signaled, for example, in a short control channel SL1, SL2, and the SPRS reference is sent following the control channel. The transmission of other SPRS radio node groups may share the channel on-time COT of the initial SPRS transmission. The initial SPRS transmission may only be made after channel contention. Thus, in general, the fifth option results in a group of multiple radio nodes UE-G1, UE-G2 to UE-GK performing position determination on the unlicensed band F2, where a first radio node UE1 in the group of first radio nodes UE-G1 forms a channel contention LBT-E to access the unlicensed band F2 initially, thus starting the channel on-time during SPRS-T1, at which point the first SPRS and control information SL1 are sent from the first radio node UE1. Other wireless nodes in other groups of wireless nodes UE-G2, UE-GK may then share the channel on-time in SPRS-T1 for transmitting subsequent position determination signals. Initial access of the unlicensed channel F2 is optionally performed using CAT-4 LBT. Subsequent access to the unlicensed channel in the channel on-time in SPRS-T1 is performed using LBT-short (CAT-2) signaling.

[0072] FIG. 10 illustrates generally another example of a signaling protocol for establishing an SPRS exchange on an unlicensed carrier using control signals sent on the unlicensed carrier. In the example of FIG. 10, a first radio node UE1, a second radio node UE2, and a third radio node UE3 communicate through an unlicensed band F2. Initially, a resource pool in the unlicensed band is configured 80 by pre-configuration received from the UE or gNB, or by a previously stored configuration. The first radio node UE1 forms a channel contention (LBT) 81, and if successful 82 transmits a short control for configuring subsequent signaling and a first SPRS configuration 83 to at least the second radio node UE2 and optionally to the third radio node UE3 (the third radio node UE3 can passively receive all SPRS transmitted by the first radio node UE2 and use it for position determination). The second radio node UE2 transmits its SPRS 84 within a tolerance gap 88 initiated by the transmission of the short control and the first SPRS. The first radio node UE1, and optionally the third radio node UE3, receive the SPRS transmitted by the second radio node UE2. If an amount of time 89 greater than the allowed gap 88 has elapsed, the third radio node UE3 must perform a new channel contention operation UE3 to access the unlicensed band as soon as the channel contention is completed, and the third radio node transmits an updated short control S-CTRL and its SPRS on the unlicensed band F2.

[0073] FIG. 11 illustrates generally an example of an SPRS format definition 100. In Figure 11, the positions of resource elements included in the SPRS interlace pattern are defined according to time slots S1-14 frequency subcarrier offset K. Spacing 101 is the number of OFDM symbols used to transmit the sidelink position reference signal (SPRS). Resource elements 102 are comb elements that form part of the position reference signal.

[0074] The initial position reference signal may be, for example, an SPRS comb as defined in accordance with 3GPP Release 16, such as in TS 138.211, section 7.4.1.7, the contents of which are incorporated herein by reference, but are not essential.

[0075] The offset configuration of the subcarriers within the SPRS comb is defined by A, B, C, D, and E. According to an embodiment, the SPRS used in all the above options has an interlaced structure. The interlaced structure covers a predefined percentage of the unlicensed band F2. In one example, the SPRS may occupy 50%, 60%, 70%, 80%, 90%, 95%, or 100% of the unlicensed band F2. In one embodiment, each radio node group UE-G1, UE-G2, UE-GK discussed above comprises a set of radio nodes that multiplex their SPRS over a predefined occupancy percentage of the unlicensed band F2 at a nominal frequency (e.g., 20 MHz). In one example, if all radio nodes in the radio node group UE-G1 are transmitting their SPRS, the entire band is interleaved by SPRS resource elements. Otherwise, only the radio nodes UE in the radio node group UE-G1 that have been successful in channel contention (LBT) for the unlicensed band F2 can share the SPRS portion of the unlicensed band F2 using the interlaced structure.

[0076] According to an embodiment of the first aspect, the method includes the steps of: prior to transmitting the SPRS configuration 72, 83 to the second radio node UE2, performing a channel contention LBT on the control signaling in a bandwidth range that is at least partially comprised in the unlicensed radio band F2 using a listen-before-talk mechanism; accessing the channel for a duration of a channel on-time associated with the channel contention based on a positive result of the channel contention LBT on the control signaling; and the step of transmitting the SPRS configuration 72, 83 to the second radio node UE2 includes a step of transmitting the SPRS configuration 72, 83 within a bandwidth range of the unlicensed radio band (F2) during a channel on-time associated with channel contention for control signaling.

[0077] According to one embodiment, the SPRS configuration 72, 83 comprises an SPRS format definition 100 that defines a portion of resource elements of an unlicensed radio band F2 to be occupied by at least one location reference signal transmitted by a first radio node UE1. The first radio node UE1 is configured to transmit to a second radio node UE2 the at least one location reference signal defined by the SPRS format definition over a plurality of subcarriers within a bandwidth range that is at least partially comprised in the unlicensed radio band F2.

[0078] According to one embodiment, the SPRS format definition 100 has multiple subsets, each corresponding to a plurality of further wireless nodes, and the SPRS format definition is designed to fully occupy the unlicensed wireless band F2 when all of the wireless nodes in the plurality of further wireless nodes obtain a positive result in the channel contention LBT operation.

[0079] According to one embodiment, the SPRS format definition 100 defines a plurality of subsets of SPRS patterns, each corresponding to a further radio node in the plurality of radio nodes UE-G1. The SPRS format definition by the first radio node UE1 defines an SPRS that is distributed across a predetermined portion of the unlicensed radio band F2. The plurality of further radio nodes UE-G1 are configured to interleave their respective SPRS transmissions according to the SPRS format definition to obtain positive results in channel contention (LBT) operations.

[0080] According to a second aspect, a method 46 for a second radio node UE2 is provided, the method comprising: - transmitting 47 from the first radio node UE1 to the first radio node UE1 a sidelink position reference signal configuration defining at least one position reference signal to be transmitted to the second radio node UE2; a step 48 of receiving at least one sidelink position reference signal transmitted by the first radio node UE1 within a bandwidth range at least partially comprised in the unlicensed radio band F2, the at least one sidelink position reference signal being defined by a sidelink position reference signal configuration; Includes.

[0081] FIG. 4b illustrates diagrammatically a method for a second radio node according to a second aspect. According to an embodiment of the second aspect, the SPRS configuration 72, 83 is transmitted to the first radio node UE1 over a sidelink in the licensed radio band F1 of the radio access network.

[0082] According to an embodiment of the second aspect, the SPRS configuration 72, 83 is transmitted over at least one of the Physical Sidelink Shared Channel PSSCH, the Physical Sidelink Control Channel PSCCH, the Physical Downlink Shared Channel PDSCH, the Physical Downlink Control Channel PDCCH or the Physical Sidelink Broadcast Channel PSBCH of the radio access network.

[0083] According to one embodiment of the second aspect, the SPRS configuration 72, 83 defines synchronization of at least one position reference signal to at least one transmission opportunity of a side channel; The first radio node UE1 is configured to receive at least one position reference signal transmitted by the second radio node UE2 synchronized to at least one transmission opportunity of the side channel defined in the SPRS configuration 72, 83.

[0084] According to the above embodiment, a method in the second radio node UE2 is effected corresponding to a first option in which data and / or control for preparing the SPRS is transmitted on a sidelink in the licensed band F1.

[0085] According to an embodiment of the second aspect, the SPRS configuration 72, 83 comprises a periodicity specifier 80 defining a number of further position reference signal transmission opportunities of the second wireless node UE2 and / or a number of further wireless nodes relative to an initial position reference signal transmission opportunity; The method includes receiving a plurality of further position reference signals 76, 87 transmitted by a corresponding plurality of further wireless nodes, the plurality of further position reference signals occupying a plurality of subcarriers within a bandwidth range that is at least partially included in the unlicensed radio band F2.

[0086] According to an embodiment of the second aspect, the SPRS configuration 72, 83 comprises a schedule of further position reference signal 76, 87 transmission opportunities of the second wireless node UE2 and / or the plurality of further wireless nodes.

[0087] According to one embodiment of the second aspect, the method further comprises a step of calculating a position of at least a second radio node UE2 relative to the first radio node UE1 using at least one position reference signal transmitted by the first radio node.

[0088] According to one embodiment of the second aspect, the position of at least the second radio node UE2 relative to the first radio node UE1 is calculated using the radiation angle or the round trip time. According to one embodiment of the second aspect, the SPRS configuration 72, 83 defines an SPRS format definition 100 that defines a portion of resource elements of the unlicensed radio band F2 to be occupied by at least one location reference signal transmitted by the second radio node UE2.

[0089] According to an embodiment of the second aspect, the SPRS format definition k defines a plurality of subsets of SPRS patterns, each SPRS pattern corresponding to a further radio node in the plurality of radio nodes UE-G1. The SPRS format definition by the first radio node UE1 defines an SPRS that is distributed across a predetermined portion of the unlicensed radio band F2. The plurality of further radio nodes UE-G1 are configured to interleave their respective SPRS transmissions according to the SPRS format definition to obtain a positive result in channel contention (LBT) operation.

[0090] According to one embodiment of the second aspect, at least the first UE1 and the second UE2 radio nodes are members of a 5G NR radio network. According to one embodiment of the second aspect, the channel contention LBT returns a negative result in response to detecting the presence of Wi-Fi or Bluetooth transmissions or other interfering signals in the unlicensed radio band F2.

[0091] According to one embodiment of the second aspect, the licensed radio band F1 comprises a vehicle-to-everything (V2X) sub-band of a 5G NR radio network. FIG. 12 illustrates diagrammatically an example of a first or second radio node according to the third and / or fourth aspect.

[0092] Apparatus embodiment According to a third aspect, a first radio node 90 is provided, comprising a radio modem 92, a non-transitory computer readable medium 94 with machine readable instructions, and a processor 95 configured to load and execute the machine readable instructions to cause the first radio device to perform a method according to the first aspect or an embodiment thereof and thereby to transmit a modified position reference signal over at least one sidelink channel to a second radio node. The first radio node UE1 is in one example configured to communicate using at least a vehicle-to-everything (V2X) sub-band of a 5G NR wireless network and to transmit a sidelink position reference signal over a portion of an unlicensed band.

[0093] According to a fourth aspect, a second radio node is provided, the second radio node comprising a radio modem, a non-transitory computer readable medium with machine readable instructions, and a processor configured to load and execute the machine readable instructions to cause the second radio node to perform a method according to the second aspect or an embodiment thereof. The second radio node UE1 is in one example configured to communicate using at least a vehicle-to-everything (V2X) sub-band of a 5G NR wireless network and to transmit a sidelink position reference signal over a portion of an unlicensed band.

[0094] The first and / or second wireless communication device 90 may comprise an input interface 93 configured to receive input data 91, e.g., commands from a higher layer to perform a position determination. The wireless communication device 90 may comprise a power source 97. The wireless communication device may comprise an antenna 92 ​​coupled to the wireless modem 90. The wireless communication device may support device-to-device, Internet of Things, and V2X communications.

[0095] Wireless communication system According to a fifth aspect, there is provided a system 8 comprising at least a first radio node UE1 according to the third aspect and a second radio node UE2 according to the fourth aspect. The system 8 is configured to communicate, for example, using at least a vehicle-to-everything (V2X) sub-band of a 5G NR radio network and to transmit a sidelink position reference signal over a portion of an unlicensed band.

[0096] Computer implementation According to a sixth aspect there is provided a computer program element comprising machine readable instructions which, when loaded and executed by a processor, causes the processor to perform a method according to the first aspect.

[0097] According to a seventh aspect there is provided a computer program element comprising machine readable instructions which, when loaded and executed by a processor, causes the processor to perform a method according to the second aspect.

[0098] According to an eighth aspect, there is provided a non-transitory computer readable medium comprising machine readable instructions of the sixth or seventh aspects. According to a ninth aspect, there is provided a vehicle comprising a wireless communication node according to one of the third or fourth aspects.

[0099] The examples shown in the drawings and described in the above description are intended to provide an understanding of the principles of the present specification. No limitations are intended thereby on the scope of the appended claims. This specification describes variations and modifications to the examples shown. Only preferred examples have been presented, and all changes, modifications, and further applications thereto that fall within the scope of this specification are desired to be protected.

Claims

1. A method (40) for a first wireless node (UE1), comprising: - transmitting (41) from a first radio node (UE1) a sidelink position reference signal configuration (SPRS configuration 72, 83) defining at least one position reference signal to be transmitted from said first radio node (UE1) to a second radio node (UE2); - generating (42) at least one position reference signal defined by said SPRS configuration to be transmitted to said second wireless node (UE2); - a step (43) of performing channel contention (LBT) for the purpose of transmitting a location reference signal within a bandwidth range that is at least partially included in an unlicensed radio band (F2), said contention being performed using a listen-before-talk mechanism; accessing the channel for a duration of a channel on-time based on a positive outcome of the channel contention (44); transmitting (45) said at least one location reference signal to said second wireless node (UE2) during said channel on-time; A method (40).

2. The method (40) of claim 1, wherein the SPRS configuration (72, 83) is transmitted to the second radio node (UE2) over a sidelink channel in a licensed radio band (F1) of a radio access network.

3. 3. The method according to claim 1, wherein the SPRS configuration is transmitted by the first radio node over at least one of a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Control Channel (PSCCH), a Physical Downlink Shared Channel (PDSCH), a Physical Downlink Control Channel (PDCCH) or a Physical Sidelink Broadcast Channel (PSBCH) of the radio access network.

4. transmitting to said second wireless node (UE2) a periodicity designator (80) defining a plurality of further position reference signal (76, 87) transmission opportunities of said first wireless node (UE1) and / or a plurality of further wireless nodes relative to an initial position reference signal transmission opportunity (SPRS-T1); performing, at the first wireless node (UE1), a plurality of further channel contention (LBT) operations corresponding to each of the plurality of position reference signal transmission opportunities; accessing the channel for a duration of the channel on-time based on at least one positive outcome of the further channel contention operation; transmitting at least one further location reference signal (76, 87) to said second wireless node (UE2) during said channel on-time defined by said periodicity designator (80); The method (40) of any one of claims 1 to 3, further comprising:

5. transmitting a schedule of further position reference signal (76, 87) transmission opportunities of said first wireless node (UE1) and / or a plurality of further wireless nodes to said second wireless node (UE2); performing, at the first wireless node (UE1), a plurality of further channel contention (LBT) operations corresponding to each of the plurality of position reference signal transmission opportunities; accessing the channel for a duration of the channel on-time based on at least one positive result of the further channel contention operation (LBT); transmitting at least one further location reference signal (76, 87) to said second wireless node (UE2) during said channel on-times defined in a schedule of further location reference signal transmission opportunities; The method (40) of any one of claims 1 to 4, further comprising:

6. The channel contention (LBT) performed by the first wireless node (UE1) for the purpose of transmitting a location reference signal is a category 4 listen-before-talk operation. The method (40) according to any one of claims 1 to 5.

7. The method (40) according to any one of claims 1 to 6, wherein the channel contention (LBT) performed by the first wireless node (UE1) for further location reference signal (76, 87) transmission opportunities is a category 2 listen-before-talk operation.

8. The method (40) according to any one of claims 1 to 7, wherein the SPRS configuration (72, 83) transmitted by the first radio node (UE1) is received within the bandwidth range of the unlicensed radio band (F2) during the channel on-time associated with channel contention (LBT) for control signaling.

9. obtaining synchronization of the at least one position reference signal to at least one transmission opportunity of the side channel from the SPRS arrangement (72, 83); during the at least one transmission opportunity of the side channel, for a position reference signal transmission, if the channel contention (LBT) is positive; transmitting said at least one location reference signal to said second wireless node (UE2) during said channel on-time; The method (40) of any one of claims 1 to 8, further comprising:

10. the SPRS configuration (72, 83) comprises a SPRS format definition (100) defining a portion of resource elements of the unlicensed radio band (F2) to be occupied by the at least one location reference signal transmitted by the first radio node (UE1); The method (40) according to any one of claims 1 to 9, comprising the step of transmitting at least one position reference signal defined by said SPRS format definition to said second radio node (UE2) over a plurality of subcarriers within a bandwidth range that is at least partially comprised in said unlicensed radio band (F2).

11. the SPRS format definition (100) defines a plurality of subsets of SPRS patterns, each SPRS pattern corresponding to a further radio node in the plurality of radio nodes UE-G1, the SPRS format definition transmitted by the first radio node (UE1) defines SPRS distributed over a predetermined portion of an unlicensed radio band (F2), and the plurality of further radio nodes UE-G1 are configured to interleave their respective SPRS transmissions in accordance with the SPRS format definition so as to obtain a positive result in a channel contention (LBT) operation; 11. The method (40) of claim 10.

12. - before transmitting said SPRS configuration (72, 83) to said second radio node (UE2), performing channel contention (LBT) for control signaling within a bandwidth range that is at least partially comprised in an unlicensed radio band (F2) using a listen-before-talk mechanism; accessing the channel for a duration of a channel on-time associated with the channel contention based on a positive outcome of the channel contention (LBT) to a control signaling; and wherein transmitting the SPRS configuration (72, 83) to the second radio node (UE2) comprises transmitting the SPRS configuration (72, 83) within the bandwidth range of the unlicensed radio band (F2) during the channel on-time associated with the channel contention for control signaling. The method (40) according to any one of the preceding claims.

13. The method (40) according to any one of claims 1 to 12, wherein at least the first (UE1) and second (UE2) radio nodes are members of a 5G NR radio network.

14. The method (40) of any preceding claim, wherein the licensed radio band (F1) comprises a vehicle-to-everything (V2X) sub-band of the 5G NR radio network.

15. 15. The method (40) according to any one of claims 1 to 14, wherein the unlicensed radio band (F2) is comprised within at least one of the following ranges: 5150-5925 MHz; 5150-5350 MHz (WAS / RLAN); 5470-5725 MHz (WAS / RLAN); 5725-5855 MHz (FWA); 5855-5875 MHz; 5875-5925 MHz (ITS), 5150-5250 (U-NII-1), 5250-5350 (U-NII-2A), 5350-5470 (U-NII-2B), 5470-5725 (U-NII-2C), 5725-5850 (U-NII-3), or 5850-5925 (U-NII-4).

16. The method (40) according to any one of claims 1 to 15, wherein the first (UE1) and / or second (UE2) radio node operates in a frame based equipment mode or a load based equipment mode.

17. A method (46) for a second wireless node (UE2), comprising: - transmitting (47) to a first radio node (UE1) a sidelink position reference signal configuration defining at least one position reference signal to be transmitted from said first radio node (UE1) to said second radio node (UE2); receiving (48) at least one sidelink position reference signal transmitted by the first radio node (UE1) within a bandwidth range that is at least partially comprised in an unlicensed radio band (F2), the at least one sidelink position reference signal being defined by the sidelink position reference signal configuration; A method (46), comprising:

18. 20. The method (46) of claim 17, wherein the SPRS configuration (72, 83) is transmitted to the first radio node (UE1) over a sidelink in a licensed radio band (F1) of a radio access network.

19. 19. The method (46) according to claim 17 or 18, wherein the SPRS configuration (72, 83) is transmitted over at least one of a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Control Channel (PSCCH), a Physical Downlink Shared Channel (PDSCH), a Physical Downlink Control Channel (PDCCH) or a Physical Sidelink Broadcast Channel (PSBCH) of the radio access network.

20. the SPRS configuration (72, 83) defines synchronization of the at least one position reference signal to at least one transmission opportunity of the side channel; the first radio node (UE1) is configured to receive at least one position reference signal transmitted by the second radio node (UE2) synchronized to the at least one transmission opportunity of the side channel defined in the SPRS configuration (72, 83); A method (46) according to any one of claims 17 to 19.

21. said SPRS configuration (72, 83) comprising a periodicity specifier (80) defining a number of further position reference signal transmission opportunities of said second wireless node (UE2) and / or a number of further wireless nodes relative to an initial position reference signal transmission opportunity; A method (46) according to any one of claims 17 to 20, comprising the step of receiving a plurality of further position reference signals (76, 87) transmitted by a corresponding plurality of further radio nodes, said plurality of further position reference signals occupying a plurality of subcarriers within a bandwidth range that is at least partially comprised in said unlicensed radio band (F2).

22. The method (46) according to any one of claims 17 to 21, wherein the SPRS configuration (72, 83) comprises a schedule of further position reference signal (76, 87) transmission opportunities of the second wireless node (UE2) and / or a number of further wireless nodes.

23. The method (46) according to any one of claims 17 to 22, further comprising a step of calculating a position of at least the second wireless node (UE2) relative to the first wireless node (UE1) using the at least one position reference signal transmitted by the first wireless node.

24. the position of at least the second wireless node (UE2) relative to the first wireless node (UE1) is calculated using a radiation angle or a round trip time; 24. The method of claim 23 (46).

25. said SPRS configuration (72, 83) comprising a SPRS format definition (100) defining a portion of resource elements of said unlicensed radio band (F2) to be occupied by said at least one location reference signal transmitted by said second radio node (UE2); A method (46) according to any one of claims 17 to 24.

26. The method of claim 25, wherein the SPRS format definition (100) defines a plurality of subsets of SPRS patterns, each SPRS pattern corresponding to a further radio node in the plurality of radio nodes UE-G1, the SPRS format definition from the first radio node (UE1) defines SPRS distributed across a predetermined portion of an unlicensed radio band (F2), and the plurality of further radio nodes UE-G1 are configured to interleave their respective SPRS transmissions in accordance with the SPRS format definition to obtain positive results in channel contention (LBT) operations.

27. A method (46) according to any one of claims 17 to 26, wherein at least the first (UE1) and second (UE2) radio nodes are members of a 5G NR radio network.

28. A method (46) according to any one of claims 17 to 27, wherein the channel contention (LBT) returns a negative result in response to detecting the presence of Wi-Fi or Bluetooth transmissions in the unlicensed radio band (F2).

29. The method (46) of any one of claims 17 to 28, wherein the licensed radio band (F1) comprises a vehicle-to-everything (V2X) sub-band of the 5G NR radio network.

30. 30. A method (46) according to any one of claims 17 to 29, wherein the unlicensed radio band (F2) is comprised within at least one of the following ranges: 5150-5925 MHz; 5150-5350 MHz (WAS / RLAN); 5470-5725 MHz (WAS / RLAN); 5725-5855 MHz (FWA); 5855-5875 MHz; 5875-5925 MHz (ITS), 5150-5250 (U-NII-1), 5250-5350 (U-NII-2A), 5350-5470 (U-NII-2B), 5470-5725 (U-NII-2C), 5725-5850 (U-NII-3), or 5850-5925 (U-NII-4).

31. A method (46) according to any one of claims 17 to 30, wherein the first (UE1) and / or second (UE2) radio node operates in a frame based equipment mode or a load based equipment mode.

32. A first wireless node (90), A wireless modem (92); A non-transitory computer readable medium (94) having machine readable instructions; a processor (95) configured to load and execute said machine-readable instructions to cause a first radio device to perform the method of any one of claims 1 to 16 and thereby to transmit a modified position reference signal to a second radio device over at least one sidelink channel; A first wireless node (90).

33. a second wireless node, A wireless modem; a non-transitory computer readable medium having machine readable instructions; a processor configured to load and execute said machine-readable instructions to cause a second wireless device to perform the method of any one of claims 17 to 31; A second wireless node comprising:

34. A system (UE1, UE2) for wireless communication, A first radio node (UE1) as defined by claim 32, A second radio node (UE2) as defined by claim 33; A system (UE1, UE2) comprising:

35. A computer program element comprising machine-readable instructions which, when loaded and executed by a processor, causes said processor to perform the method according to any one of claims 1 to 16.

36. A computer program element comprising machine-readable instructions which, when loaded and executed by a processor, causes said processor to perform the method of any one of claims 17 to 31.

37. 37. A non-transitory computer readable medium comprising machine readable instructions as defined by any one of claims 35 or 36.

38. A vehicle comprising a wireless communication node according to any one of claims 32 and 33.

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