Method for operating a network infrastructure-side network unit, network infrastructure-side network units, method for operating a roadside network unit, roadside network unit

Description

State of the art

[0001] The invention relates to a method for operating a network infrastructure-side network unit and a network infrastructure-side network unit.

[0002] US 2015 / 0334643 A1 discloses that allocating traffic to be transported over either the primary band or the complementary band of a unified air interface based on traffic quality of service (QoS) constraints can enable improved efficiency in network resource utilization. In one example, traffic with deterministic QoS constraints is allocated to the primary band, while traffic with statistical QoS constraints is allocated to the complementary band if the complementary band is capable of satisfying the traffic's statistical QoS constraints. If a condition on the complementary band prevents it from satisfying the traffic's statistical QoS constraint, the traffic is allocated to the primary band.

[0003] EP 3 171 650 A1 discloses a wireless communication system comprising: a plurality of terminal devices, each configured to support D2D communication; and a base station configured to control the plurality of terminal devices and provide a wireless communication service using a licensed band. The base station selects a terminal device from the plurality of terminal devices based on information received from the plurality of terminal devices and transmits a measurement instruction instructing the measurement of a usage state of an unlicensed band to the selected terminal device. The selected terminal device measures a usage state for each subband in the unlicensed band according to the measurement instruction and transmits a measurement result to the base station.Based on the measurement result, the base station determines an available subband in the unlicensed band for D2D communication and sends subband information indicating the determined subband to a terminal device performing D2D communication.

[0004] WO 2007 / 018697 A1 discloses a system and method for managing licensed and unlicensed frequency bands in a wireless wide area network. The method comprises determining the available channels of a licensed and unlicensed frequency band. Data traffic is prioritized for channel allocation. Higher-priority data traffic is assigned to the licensed frequency band, and lower-priority data traffic is assigned to the unlicensed frequency band. Channel quality is determined, with higher-priority traffic being assigned to quieter channels. Data traffic is shifted from the channels of the unlicensed frequency band to the channels of the licensed frequency band if the quality of the channels of the unlicensed frequency band falls below a predetermined acceptable threshold.

[0005] It is known that vehicles are already capable of exchanging information with other vehicles in their vicinity (V2V: Vehicle to Vehicle). Vehicles can also communicate wirelessly with roadside infrastructure (V2I: Vehicle to Infrastructure). Likewise, the vehicle can communicate wirelessly with a backend server on the internet (V2N: Vehicle to Network) or with a pedestrian device (V2P: Vehicle to Person). This type of communication is collectively referred to as Vehicle-to-Everything (V2X).

[0006] The development of new functions and services in the automotive industry, such as automated driving, benefits from V2X. Traffic safety, driving comfort, and energy efficiency can be improved. This leads to new products and business models for automakers, automotive suppliers, and other service providers.

[0007] The first generation of V2X applications, which will be deployed in the coming years, is primarily focused on road use. Their goal is to provide drivers with information about the road environment. Vehicles periodically provide status information (e.g., position, speed, acceleration, etc.) and / or event information (emergency response, broken-down vehicle, traffic jam). This information is typically sent locally in the form of short messages. Neighboring vehicles can send this event-based information to a central network unit (base station, backend).

[0008] There are currently two competing technologies for V2X Direct Device-to-Device (D2D) communication. The first technology is based on the IEEE 802.11p standard, which forms the basis for the overarching DSRC (Dedicated Short Range Communication) standards in the USA and ETSI ITS G5 (ETSI: European Telecommunications Standards Institute; ITS: Intelligent Transport Systems) in Europe. The second technology is based on 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) and is also known by the abbreviation LTE-V2X. A further development of LTE-V2X technology is expected with 5G (5th generation mobile networks).

[0009] The IEEE 802.11p standard uses the PHY layer of the IEEE 802.11a standard based on Orthogonal Frequency Division Multiplexing (OFDM) with some modifications. The MAC layer is based on Enhanced Distributed Channel Access (EDCA), which is contention-based. Carrier Sense Multiple Access (CSMA) with Collision Avoidance (CSMA / CA) is also used. CSMA / CA follows the Listen-Before-Talk principle to minimize collisions on the channel. When a network device (in this context, a vehicle) has data to transmit, it performs a channel measurement to check whether the channel is occupied. If the channel is detected as empty, the network device waits a randomly determined time before beginning the scheduled transmission and then begins the transmission. If the channel is occupied during the channel measurement, the network device performs a backoff procedure, i.e.It waits a randomly determined period of time before attempting the next channel access. The higher the number of network units attempting to transmit in a geographical area, the higher the probability that a network unit will delay its transmission, leading to overall increased delays in the network. The IEEE 802.11p standard offers advantages over other WLAN standards based on IEEE 802.11 in terms of latency and signaling overhead and is adapted to the V2V use case.

[0010] The LTE extension for V2X starting with 3GPP Release 14 proposes the use of licensed and / or unlicensed spectrum for communication. V2V communication is based on a direct device-to-device interface (also known as a sidelink interface at the physical layer). Unlike 802.11p, transmission is cell-based, meaning it is scheduled by the network. Transmission rights are granted by a scheduler unit located in the base station, thus avoiding collisions and minimizing interference. Base station control can only be exercised in areas where the base station signal is available (in-coverage). In a case where no base station signal is available (out-of-coverage), communication takes place over the sidelink with predefined parameters.

[0011] The 5G Automotive Association (5GAA) wants to use the 5.9 GHz ITS frequency spectrum, where ITS-G5 systems also operate. This poses a threat to the future of ITS-G5 systems and their deployment, as some automakers have already announced plans to install ITS-G5-based systems in their cars. This would result in two different wireless communication systems transmitting in the same unlicensed frequency range, resulting in performance degradation for both technologies.

[0012] Therefore, an objective technical task could be formulated as creating a coexistence mechanism for the two different wireless communication technologies in order to fairly allocate available resources. Disclosure of the invention

[0013] The problem underlying the invention is solved by methods for operating a network infrastructure-side network unit according to claim 1 and a roadside network unit according to claim 12.

[0014] According to one aspect, a method for operating a network infrastructure-side network unit and a network infrastructure-side network unit is proposed. A first group of roadside network units is determined within the cell of the network infrastructure-side network unit. A second group of roadside network units is determined within the cell of the network infrastructure-side network unit, wherein the first and second groups are disjoint. A first scheduling request message is received on the uplink channel from a first roadside network unit of the first group. A first scheduling grant message is determined, wherein the first scheduling grant message comprises an allocation of at least one sidelink resource of the first sidelink channel in the unlicensed frequency range to the first roadside network unit of the first group.The first scheduling grant message is sent on a downlink channel to the first roadside network unit. A second scheduling request message is received on the uplink channel from a second roadside network unit of the second group. A second scheduling grant message is determined, wherein the second scheduling grant message comprises an allocation of at least one sidelink resource of the second sidelink channel in the licensed frequency range to the second roadside network unit of the second group. The second scheduling grant message is sent on the downlink channel to the second roadside network unit.

[0015] According to this aspect, the reliability of message transmission over a sidelink channel is advantageously improved, since dividing the roadside network units into two groups involves distributing the traffic between the first and second sidelink channels. By grouping them into the second group, roadside network units are removed from the first sidelink channel and free up resources for other network units that are not controlled by the network infrastructure-side network unit, for example, ITS-G5 network units.

[0016] What all aspects have in common is that the traffic between the network units, which are scheduled by the network infrastructure-side network unit, is distributed via two sidelink channels.

[0017] Further features and advantages can be found in the following description of exemplary embodiments. The drawing shows: Figure 1 shows a first cell-based wireless communication network and a second wireless communication network; Figures 2, 3, 5, 8, and 9 each show a schematic flow diagram; Figures 4 and 6 each show a schematic sequence diagram; and Figure 7 shows a schematic block diagram for determining a collision probability.

[0018] Figure 1shows a first cell-based wireless communication network CELL and a second wireless communication network VANET. The first wireless communication network CELL comprises a network infrastructure-side network unit BS, a first roadside network unit UE1, and a second roadside network unit UE2. The network infrastructure-side network unit BS comprises a processor P_BS, a memory element M_BS, and a transceiver T_BS. The network infrastructure-side network unit BS can also be referred to as a base station or eNodeB. The network infrastructure-side network unit BS is connected to a stationary antenna A_BS to transmit data on a downlink channel DC and to receive data on an uplink channel UC. The antenna A_BS comprises, for example, a number of antennas and is designed, for example, as a Remote Radio Head (RRH).The network infrastructure-side network unit BS and the antenna A_BS provide a cell C, within which the roadside network units UE1 and UE2 communicate with the network unit BS. Of course, the network infrastructure-side network unit BS can also be distributed within the framework of virtualization and consist of individual network units. For example, the network units BS, UE1, and UE2 are configured according to the LTE-V2X standard.

[0019] The roadside network units UE1 and UE2 each comprise a processor P1, P2, a memory element M1, M2, a transceiver T1, T2, and an antenna A1, A2. The two roadside network units UE1, UE2 are located within cell C, receive data on the downlink channel DC, and transmit data on the uplink channel UC. The two roadside network units UE1, UE2 can communicate directly with each other via a first sidelink channel SC1 in an unlicensed frequency range NLFB and via a second sidelink channel SC2 in a licensed frequency range LFB.

[0020] The two roadside network units UE1 and UE2 are located within cell C and are capable of receiving data on the downlink channel DC and transmitting data on the uplink channel UC. The two roadside network units UE1 and UE2 are capable of communicating directly with each other via a sidelink channel SC1 in an unlicensed frequency range NLFB and via a sidelink channel SC2 in a licensed frequency range LFB.

[0021] National authorities, such as the Federal Network Agency of the Federal Republic of Germany, draw up a frequency usage plan, which includes, for example, licenses for a particular network operator. Within the scope of the assigned license, the network operator is permitted to use the network infrastructure and terminal equipment within an assigned, i.e., licensed, frequency range or frequency spectrum. In contrast, there are frequency ranges or frequency spectra that are not assigned to any network operator and are freely usable under certain conditions, such as reduced transmission / reception power.

[0022] This description refers to a single uplink channel and a single downlink channel. For example, the uplink channel and the downlink channel comprise respective subchannels, meaning multiple channels can be used in both the uplink and downlink. The same applies to the sidelink channels SC1 and SC2.

[0023] The second wireless communication network (VANET) comprises two additional roadside network units NE3 and NE4, each comprising a processor P3, P4, a memory element M3, M4, a transceiver T3, T4, and an antenna A3, A4. The network units NE3 and NE4 are configured, for example, according to the IEEE 802.11p standard. The network units NE3 and NE4 communicate directly with each other via an ad hoc channel (ADCH) in the unlicensed frequency range NLFB. The ad hoc channel (ADCH) is arbitrated by the transceivers T3, T4 using a CSMA / CA protocol (CSMA / CA: Carrier Sense Multiple Access / Collision Avoidance).

[0024] The memory elements M1, M2, M3, and M4 store respective computer programs that, when executed on the respective processors P1, P2, P3, and P4, implement the methods disclosed in this description. Alternatively, the processors P1, P2, P3, and P4 are implemented as ASICs.

[0025] The third and fourth network units NE3 and NE4 are located in proximity to the first and second network units UE1 and UE2, particularly within a Cell C area, so that their respective transmission power is sufficient to interfere with transmissions by the network units UE1 and UE2 in the unlicensed NLFB frequency range. Consequently, transmissions on the ADCH and SC1 channels can adversely affect each other. The objective of this description is to reduce this adverse mutual interference.

[0026] The sidelink channels SC1 and SC2 are operated in a so-called managed mode, which means that the network unit BS controls transmission on the sidelink channels SC1 and SC2 via corresponding messages in the downlink channel DC. The ad hoc channel ADCH, however, is not operated in a managed mode. The roadside network units NE3 and NE4 therefore access the ad hoc channel ADCH independently.

[0027] The roadside network units UE1, UE2, NE3, and NE4 are arranged in respective motor vehicles vehic1, vehic2, vehic3, and vehic4 and are connected to a control unit (not shown) arranged therein for data exchange. Alternatively, the roadside network units UE1, UE2, NE3, and NE4 are part of the control unit in the respective motor vehicle vehic1, vehic2, vehic3, and vehic4. In a further alternative embodiment, the roadside network units UE1, UE2, NE3, and NE4 are arranged in a fixed infrastructure, such as a traffic light, instead of in a motor vehicle.

[0028] The sidelink channels SC1, SC2, and a sidelink in general, are defined, for example, by document 3GPP TS 36.300 V14.2.0 (2017-03), which is incorporated into this description by reference. The sidelink includes sidelink discovery, sidelink communication, and V2X sidelink communication between the network entities UE1 and UE2. The sidelink uses uplink resources and a physical channel structure similar to that of the uplink. The sidelink therefore differs from the uplink in terms of the physical channel.

[0029] The sidelink is limited to single cluster transmissions for the physical sidelink channels. Furthermore, the sidelink uses a one-symbol gap at the end of each sidelink subframe. For V2X sidelink communication, the PSCCH (Physical Sidelink Control Channel) and PSSCH (Physical Sidelink Shared Channel) are transmitted in the same subframe. For example, the sidelink channels SC1 and SC2 are the PSSCH.

[0030] The physical layer processing of transport channels in the sidelink differs from uplink transmission in the following steps: Scrambling: For PSDCH, Physical Sidelink Discovery Channel, and PSCCH, scrambling is not specific to the network entity; Modulation: 64 QAM and 256 QAM are not supported for the sidelink (QAM: Quadrature Amplitude Modulation). The PSCCH specifies sidelink resources and other transmission parameters used by the respective network entity UE1, UE2 for the PSSCH.

[0031] For PSDCH, PSCCH, and PSSCH demodulation, reference signals similar to the uplink demodulation reference signals are transmitted in the 4th symbol of the slot in the normal CP, cyclic prefix, and in the 3rd symbol of the slot in the extended CP. The sidelink demodulation reference signal sequence length corresponds to the size (number of subcarriers) of the allocated resource. For V2X sidelink communication, reference signals are transmitted in the 3rd and 6th symbols of the first slot and in the 2nd and 5th symbols of the second slot in the CP. For PSDCH and PSCCH, reference signals are generated based on a fixed base sequence, cyclic shift, and orthogonal cover code. For V2X sidelink communication, the cyclic shift for PSCCH is randomly selected for each transmission.

[0032] For measurements of the respective sidelink channel SC1, SC2, the following options are available on the network units UE1, UE2: Reception power of the sidelink reference signal (S-RSRP); Reception power of the sidelink discovery reference signal (SD-RSRP); Reception power of the PSSCH reference signal (PSSCH-RSRP); Signal strength indicator for sidelink reference signals (S-RSSI).

[0033] The ad hoc channel ADCH and the ad hoc wireless communication network VANET, for example, are defined by the IEEE standard "802.11p-2010 - IEEE Standard for Information technology--Local and metropolitan area networks--Specific requirements--Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 6: Wireless Access in Vehicular Environments," which is incorporated into this description by reference. IEEE 802.11p is a standard extending the WLAN standard IEEE 802.11. The objective of IEEE 802.11p is to establish WLAN technology in passenger vehicles and to create a reliable interface for applications in intelligent transport systems (ITS). IEEE 802.11p is also the basis for Dedicated Short Range Communication (DSRC) in the frequency band from 5.85 to 5.925 GHz.To avoid confusion with the European DSRC version, the term ITS-G5 is used instead of DSRC, especially in Europe.

[0034] The document "ETSI EN 302 663 V1.2.0 (2012-11)", which is incorporated into this description by reference, describes the two lowest layers of ITS-G5 technology (ITS G5: Intelligent Transport Systems operating in the 5 GHz frequency band), the physical layer and the data link layer. For example, the TA1 and TA3 transceivers implement these two lowest layers and corresponding functions according to "ETSI TS 102 687 V1.1.1 (2011-07)" to use the ad hoc channel ADCH. The following unlicensed frequency ranges are available in Europe for use of the ad hoc channel ADCH, which are part of the unlicensed frequency range NLFB: 1) ITS-G5A for safety-relevant applications in the frequency range from 5.875 GHz to 5.905 GHz; 2) ITS-G5B for non-safety-critical applications in the frequency range 5.855 GHz to 5.875 GHz; and 3) ITS-G5D for the operation of ITS applications in the frequency range 5.905 GHz to 5.925 GHz.ITS-G5 enables communication between the two network entities UE1 and UE2 outside the context of a base station. ITS-G5 enables the immediate exchange of data frames and avoids the management overhead associated with network setup.

[0035] The document "ETSI TS 102 687 V1.1.1 (2011-07)", which is incorporated into this description by reference, describes a "Decentralized Congestion Control Mechanism" for ITS-G5. The ad hoc channel ADCH is used, among other things, for the exchange of data relating to traffic safety and traffic efficiency. The transceivers TA1 and TA3, for example, implement the functions described in the document "ETSI TS 102 687 V1.1.1 (2011-07)". The applications and services in ITS-G5 are based on the cooperative behavior of the roadside network units that form the ad hoc network VANET (vehicular ad hoc network). The ad hoc network VANET enables time-critical road traffic applications where rapid information exchange is necessary to provide timely warnings and assistance to the driver and / or vehicle.To ensure the proper functioning of the VANET ad hoc network, Decentralized Congestion Control Mechanisms (DCC) are used for the ITS-G5 ad hoc channel ADCH. DCC has functions located at multiple layers of the ITS architecture. The DCC mechanisms rely on channel knowledge. Channel state information is obtained through channel probing. Channel state information can be obtained using the TPC (transmit power control), TRC (transmit rate control), and TDC (transmit data rate control) methods. These methods determine the channel state information based on received signal level thresholds or preamble information from detected packets.

[0036] Figure 2shows a schematic flow diagram for operating the network infrastructure-side network unit BS. In a step 202, a scheduling request message for the first sidelink channel in the unlicensed frequency range is received on the uplink channel from one of the roadside network units. In a step 204, a first scheduling grant message is determined, wherein the first scheduling grant message comprises an assignment of at least one sidelink resource of the first sidelink channel to the roadside network unit. In a step 206, the first scheduling grant message is sent on the downlink channel to the roadside network unit. In a step 208, an indication that the assigned sidelink resource of the first sidelink channel is occupied is received on the uplink channel from the roadside network unit.In a step 210, a second scheduling grant message is determined, wherein the second scheduling grant message comprises an assignment of at least one sidelink resource of the second sidelink channel in the licensed frequency range to the roadside network unit. In a step 212, the second scheduling grant message is sent to the roadside network unit on the downlink channel.

[0037] Figure 3shows a schematic flow diagram for operating the roadside network unit UE1 or UE2. In a step 302, a message for sending to another roadside network unit is determined. In a step 304, a scheduling request message for the first sidelink channel in the unlicensed frequency range is sent on the uplink channel to the network infrastructure-side network unit. In a step 306, the first scheduling grant message is received on the downlink channel from the network infrastructure-side network unit, wherein the first scheduling grant message comprises an assignment of at least one sidelink resource of the first sidelink channel to the roadside network unit. In a step 308, it is determined that the assigned sidelink resource of the first sidelink channel is occupied.In a step 310, an indication that the assigned sidelink resource of the first sidelink channel is occupied is sent on the uplink channel to the network unit on the network infrastructure side. In a step 312, the second scheduling grant message is received on the downlink channel by the network unit on the network infrastructure side, wherein the second scheduling grant message comprises an assignment of at least one sidelink resource of the second sidelink channel to the roadside network unit. In a step 314, the message is sent to the further roadside network unit on the second sidelink channel.

[0038] Figure 4shows a schematic sequence diagram. In step 302, the roadside network unit UE1 determines a message P in the form of payload data in order to send it in a scheduled resource. The scheduling request message BSR, for example a buffer status report, is sent via the uplink channel UC to the network infrastructure-side network unit BS. In step 204, the network infrastructure-side network unit BS determines the scheduling grant message G1, which is sent to the first network unit UE1 on the downlink channel DC. After receiving the scheduling grant message G1, the network unit UE1 attempts to send the message P in step 308 according to a listen-before-talk (LBT) method. If the network unit UE1 determines that the first sidelink channel is free, it sends the message P via the assigned resource of the first sidelink channel.To do this, the network unit UE1 monitors the first sidelink channel to determine whether it is occupied or not.

[0039] In this description, a resource is understood to mean time, frequency, and / or modulation and coding scheme information that is used for transmission on one of the channels and is previously scheduled by the network unit on the network infrastructure side.

[0040] If, at the time the network unit UE1 is monitoring the channel, communication is taking place between the network units NE3 and NE4 via the ad hoc channel ADCH in the same frequency range, the network unit UE1 assumes from the channel measurement that the first sidelink channel located in the same frequency range is occupied. Indication I, which is present, for example, as bit information, indicates that the first roadside network unit UE1 was unable to use the resources assigned to it. Indication I is sent to the network infrastructure-side network unit BS via the uplink channel UC in step 310. Depending on indication I, the network infrastructure-side network unit BS determines the second grant scheduling message G2 in step 210 and transmits it to the first roadside network unit UE1 via the downlink channel DC.In step 314, the first roadside network unit UE1 sends the message P with increased reliability over the allocated resources of the second sidelink channel SC2, since the second sidelink channel SC2 is located in the licensed frequency range LSB and thus no interference from other unscheduled network units is to be expected. Thus, the second sidelink channel SC2 is used as a backup channel for the first sidelink channel.

[0041] Figure 5 shows a schematic flow diagram for operating the network infrastructure-side network unit BS from Figure 1In a step 502, a first group of roadside network units within the cell of the network infrastructure-side network unit is determined. In a step 504, a second group of roadside network units within the cell of the network infrastructure-side network unit is determined, wherein the first and second groups are disjoint. In a step 506, a first scheduling request message is received on the uplink channel from a first roadside network unit of the first group. In a step 508, a first scheduling grant message is determined, wherein the first scheduling grant message comprises an allocation of at least one sidelink resource of the first sidelink channel in the unlicensed frequency range to the first roadside network unit of the first group. In a step 510, the first scheduling grant message is sent on a downlink channel to the first roadside network unit.In a step 512, a second scheduling request message is received on the uplink channel from a second roadside network unit of the second group. In a step 514, a second scheduling grant message is determined, wherein the second scheduling grant message comprises an allocation of at least one sidelink resource of the second sidelink channel in the licensed frequency range to the second roadside network unit of the second group. In a step 516, the second scheduling grant message is sent on the downlink channel to the second roadside network unit.

[0042] Figure 6shows a schematic sequence diagram. In step 502, the network unit BS divides the roadside network units UE1 and UE2 into a respective group Gr1, Gr2. Of course, the groups Gr1 and Gr2 also include further roadside network units. In a step 602, the roadside network unit UE1 determines payload data P1 for transmission to the second roadside network unit UE2 and, in a step 604, transmits the first scheduling request message BSR1 on the uplink channel UC to the network infrastructure-side network unit BS. In step 508, the network unit BS determines the first scheduling grant message G3 in order to transmit it on the downlink channel DC in step 510. In a step 606, the first network unit UE1 checks whether the first sidelink channel SC1 is free.In the present case, this is the case and the first network unit UE1 sends the payload data P1 on the first sidelink channel SC1 of the unlicensed frequency range to the second roadside network unit UE2 in a step 608.

[0043] In a step 610, the second roadside network unit UE2 determines payload data P2 to send to the first roadside network unit UE1. To do so, in a step 612, it sends the second scheduling request message BSR2 to the network infrastructure-side network unit BS via the uplink channel UC. In step 514, the network unit BS determines the second scheduling grant message G4 for the second sidelink channel SC2 based on the second scheduling request message BSR2 and sends it to the second roadside network unit UE2 in step 516. After receiving the second scheduling grant message G4, the second roadside network unit UE2 does not perform a listen-before-talk procedure, but in a step 614 sends the payload P2 on the resources allocated by the second scheduling grant message G4 on the second sidelink channel SC2 to the first roadside network unit UE1.Simultaneous wireless communication between the roadside network units NE3 and NE4 on the ad hoc channel ADCH does not interfere with the communication according to step 614, since the frequency ranges of the ad hoc channel ADCH and the second sidelink channel SC2 differ.

[0044] Both the first and the second roadside network units UE1 and UE2 receive the scheduling grant messages G3 and G4 and are accordingly ready to receive on both the first and the second sidelink channels SC1 and SC2.

[0045] Figure 7 shows a schematic block diagram for determining a collision probability C on the first sidelink channel SC1 from Figure 1. A first item of occupancy information O1 is determined by a channel measurement of the network unit BS on the network infrastructure side on the first sidelink channel. The first item of occupancy information O1 contains the information that potential data traffic is occurring on the first sidelink channel, which could originate from both the cell-based wireless communication network CELL and the second wireless communication network VANET. Furthermore, a second item of occupancy information O2 is known by the scheduler of the network unit BS on the network infrastructure side, which second item of occupancy information O2 contains the resources scheduled, i.e., occupied, on the first sidelink channel. The second item of occupancy information O2 is present, for example, as bit information, where zero means a free state and one means an occupied state of the first sidelink channel. An exclusive-OR operation O1 XOR O2 results in a third item of occupancy information O3.Occupancy information O3 corresponds to an occupancy of the first sidelink channel by roadside network units NE3, NE4, which do not operate in the cell-based wireless communication network, for example traffic according to ETSI ITS-G5.

[0046] Consequently, the collision probability C can be determined depending on the third occupancy information O3. For example, a section A(O3) is selected from the occupancy information O3, and the collision probability C is determined according to block 702, which, for example, results in 25% for 5 of 20 time slots occupied.

[0047] Figure 8 shows a schematic flow diagram for the operation of the network infrastructure-side network unit BS. In a step 802, the collision probability on the first sidelink channel in the unlicensed frequency range is determined, for example, according to Figure 7determined. In a step 804, sidelink resources are reserved on the second sidelink channel depending on the determined collision probability. For example, if a collision probability of 20% was determined and 10 roadside network units of the cell-based wireless network are present in the cell, two resources are reserved on the second sidelink channel. In step 210, at least some of the reserved sidelink resources are scheduled, ie, a sidelink resource of the second sidelink channel is assigned to the roadside network unit that was unable to transmit its data in the first sidelink channel.

[0048] The determined reserved and / or scheduled resources in the first and second sidelink channels are distributed by the network infrastructure-side network unit BS to the first and second network units UE1 and UE2, for example, by broadcast, in particular by radio resource control messages. This can also occur during a cell attachment process or a handover process of the roadside network unit UE1, UE2.

[0049] Figure 9 shows a schematic flow diagram for the operation of the network infrastructure-side network unit BS. In step 902, the collision probability on the first sidelink channel is determined, for example, according to Figure 7In a step 904, the first group of roadside network units within the cell is determined based on the determined collision probability. In a step 906, the second group of roadside network properties within the cell is determined based on the determined collision probability. This adapts the groups to the occupancy level of the first sidelink channel.

[0050] For example, at an initial point in time, the collision probability was 0%, and ten roadside network units were assigned to the first group to transmit on the first sidelink channel in the unlicensed frequency range. If the collision probability increases to 20% at a second point in time, two roadside network units are assigned to the second group to transmit on the second sidelink channel in the licensed frequency range. Eight network units are assigned to the first group. If the collision probability subsequently decreases again, the roadside network units are transferred from the second group to the first group. This ensures that the first sidelink channel in the unlicensed frequency range is utilized as fully as possible.

Claims

1. Method for operating a network-infrastructure network unit (BS) of a cell-based wireless communication network (CELL), the method comprising: - determining (502) a first group (Gr1) of a plurality of roadside network units (UE1) within a cell (C) of the network-infrastructure network unit (BS), the roadside network units (UE1) of the first group (Gr1) being intended to use a first sidelink channel (SC1) in an unlicensed frequency band (NLFB); - determining (504) a second group (Gr2) of a plurality of roadside network units (UE2) within the cell (C) of the network-infrastructure network unit (BS), the roadside network units (UE2) of the second group (Gr2) being intended to use a first sidelink channel (SC1) in a licensed frequency band (LFB), and the first and second groups (Gr1, Gr2) being disjoint; - receiving (506) a first scheduling request message (BSR) from a first roadside network unit (UE1) of the first group (Gr1) on an uplink channel (UC); - determining (508) a first scheduling grant message (G3), the first scheduling grant message (G3) comprising an allocation of at least one sidelink resource (PRB, MCS, ...) of a first sidelink channel (SC1) in an unlicensed frequency band (NLFB) to the first roadside network unit (UE1) of the first group (Gr1); - sending (510) the first scheduling grant message (G3) to the first roadside network unit (UE1) on a downlink channel (DC); - receiving (512) a second scheduling request message (BSR) from a second roadside network unit (UE2) of the second group (Gr2) on the uplink channel (UC); - determining (514) a second scheduling grant message (G4), the second scheduling grant message (G4) comprising an allocation of at least one sidelink resource (PRB, MCS, ...) of a second sidelink channel (SC2) in a licensed frequency range (LFB) to the second roadside network unit (UE2) of the second group (Gr2); and - sending (516) the second scheduling grant message (G4) to the second roadside network unit (UE2) on a downlink channel (DC).

2. Method according to Claim 1, comprising: - determining (902) a probability of collision (C) on the first sidelink channel (SC1) in the unlicensed frequency range (NLFB); - determining the first group (Gr1) of roadside network units (UE1) within a cell (C) of the network-infrastructure network unit (BS) on the basis of the determined probability of collision (C); - determining the second group (Gr2) of roadside network units (UE2) within the cell (C) of the network-infrastructure network unit (BS) on the basis of the determined probability of collision (C).

3. Method according to Claim 2, comprising: - determining first use information (O1) pertaining to the first sidelink channel (SC1) by means of a channel measurement on the first sidelink channel (SC1).

4. Method according to Claim 3, wherein the first use information (O1) indicates data traffic coming both from the cell-based wireless communication network (CELL) and from a further wireless communication network (VANET).

5. Method according to either of Claims 3 and 4, comprising - determining second use information (O2) pertaining to the first sidelink channel (SC1), which information contains the resources scheduled on the first sidelink channel (SC1).

6. Method according to Claim 5, comprising: - determining third use information (O3) by means of an exclusive-OR operation applied to the first use information (O1) and to the second use information (O2).

7. Method according to Claim 6, wherein the third use information (O3) corresponds to a use of the first sidelink channel (SC1) by roadside network units (NE3, NE4) that do not operate in the cell-based wireless communication network (CELL).

8. Method according to Claim 7, comprising: - determining the probability of collision (C) on the basis of the third use information (O3).

9. Method according to Claim 8, comprising: - selecting a section (A(O3)) from the third use information (O3), and - determining the probability of collision (C) on the basis of the selected section (A(O3)).

10. Method according to one of Claims 2 to 9, comprising: - reserving (804) sidelink resources on the second sidelink channel (SC2) on the basis of the determined probability of collision (C).

11. Method according to one of the preceding claims, comprising: - assigning the roadside units (UE1, UE2) to a respective group (G1, G2).

12. Network-infrastructure network unit (BS) of a cell-based wireless communication network (CELL), comprising: - a processor (P_BS), which is configured to determine a first group (Gr1) of roadside network units (UE1) within a cell (C) of the network-infrastructure network unit (BS), and to determine a second group (Gr2) of roadside network units (UE2) within the cell (C) of the network-infrastructure network unit (BS), the roadside network units (UE1) of the first group (Gr1) being intended to use a first sidelink channel (SC1) in an unlicensed frequency band (NLFB), the roadside network units (UE2) of the second group (Gr2) being intended to use a first sidelink channel (SC1) in a licensed frequency band (LFB), and the first and second groups (Gr1, Gr2) being disjoint; - an antenna (A_BS) and a transceiver (T_BS), which are conditioned to receive a first scheduling request message (BSR) from a first roadside network unit (UE1) of the first group (Gr1) on an uplink channel (UC); - wherein the processor (P_BS) is configured to determine a first scheduling grant message (G3), the first scheduling grant message (G3) comprising an allocation of at least one sidelink resource (PRB, MCS, ...) of a first sidelink channel (SC1) in an unlicensed frequency band (NLFB) to the first roadside network unit (UE1) of the first group (Gr1); - wherein the antenna (A_BS) and the transceiver (T_BS) are conditioned to send the first scheduling grant message (G3) to the first roadside network unit (UE1) on a downlink channel (DC), and to receive a second scheduling request message (BSR) from a second roadside network unit (UE2) of the second group (Gr2) on the uplink channel (UC); - wherein the processor (P_BS) is conditioned to determine a second scheduling grant message (G4), the second scheduling grant message (G4) comprising an allocation of at least one sidelink resource (PRB, MCS, ...) of a second sidelink channel (SC2) in a licensed frequency band (LFB) to the second roadside network unit (UE2) of the second group (Gr2); and - wherein the antenna (A_BS) and the transceiver (T_BS) are conditioned to send the second scheduling grant message (G4) to the second roadside network unit (UE2) on a downlink channel (DC).