Grant: H2020-SESAR RPAS-05 DataLink Consortium coordinator: AAU Edition date: [28 May 2018] Edition: [01.00] Template Edition:

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1 EXPLORATORY RESEARCH DroC2om D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links DeliverableID ProjectAcronym [D4.1] DroC2om Grant: Call: H2020-SESAR Topic: RPAS-05 DataLink Consortium coordinator: AAU Edition date: [28 May 2018] Edition: [01.00] Template Edition:

2 EDITION [01.00] Authoring & Approval Authors of the document Name/Beneficiary Position/Title Date István Z. Kovács WP4 lead 30/05/2018 Jeroen Wigard Project TM 30/05/2018 Nicolas Van Wambeke WP2 lead 30/05/2018 Rafhael Amorim Contributor 30/05/2018 Reviewers internal to the project Name/Beneficiary Position/Title Date Ulrich Tuerke / atesio WP3 lead 01/05/2018 Matthieu Clergeaud / Thales Contributor 01/05/2018 Approved for submission to the SJU By - Representatives of beneficiaries involved in the project Name/Beneficiary Position/Title Date Troels B. Sørensen Project Coordinator / AAU 29/05/2018 Rejected By - Representatives of beneficiaries involved in the project Name/Beneficiary Position/Title Date 2

3 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links Document History Edition Date Status Author Justification /11/2017 DRAFT István Z. K. Slide material moved to D4.1 template; Early ToC /01/2018 DRAFT István Z. K. Add first references, abbreviations, terms. Updated ToC. 00.3x 06/03/2018 DRAFT István Z. K. Start adding content in the LTE/5G architecture sections and evaluation sections /04/2018 DRAFT István Z. K. Re-structure the evaluation and experimental mobility results sections. Add first set of 3GPP results. 00.5x 25/04/2018 DRAFT István Z. K. Jeroen W. 00.6x 30/04/2018 DRAFT István Z. K. Jeroen W /05/2018 DRAFT István Z. K. Jeroen W. Finalise reference 3GPP and site-specific results section. Move 3GPP results to Annex. Add first results with proposed solutions. Add preliminary Abstract and Summary. Write section on link to WP3. First input to the hybrid access section (moved to Section 2) Distributed for internal DroC2om review /05/2018 Final István Z. K. Incorporate reviewer s comments and suggestions. Dissemination level: Public Copyright Statement: 2018 Thales Alenia Space, Aalborg University, Nokia Bell Labs, atesio GmbH. All rights reserved. Licensed to the SESAR Joint Undertaking under conditions. 3

4 EDITION [01.00] DroC2om DRONE CRITICAL COMMUNICATIONS This technical deliverable is part of a project that has received funding from the SESAR Joint Undertaking under grant agreement No under European Union s Horizon 2020 research and innovation programme 1. Abstract In this Deliverable D4.1 we have provided an extensive analysis of 3GPP LTE terrestrial/cellular network support of UAS DataLink communications. The radio access and radio mobility mechanisms with direct impact on the performance of the UAS DataLink service have been described and evaluated. The UAS DataLink traffic model in these first evaluations was selected to be the 3GPP C2 model, which from radio access point of view requires: 99.9 % reliability within a 50 ms delay budget for transmissions of 1250 Bytes packets every 100 ms. The radio evaluation models and methodology are a direct outcome of the radio measurement and experiments documented in Deliverable D5.1. First, the radio network architecture for 3GPP LTE and 5G NR have been introduced, highlighting the main elements which are to play a key role in the terrestrial cellular network support for DataLink and later also in the integrated hybrid cellular-satellite DataLink solutions. In this Deliverable D4.1 we also started to sketch the first elements of the possible integrated hybrid cellular-satellite DataLink solutions. This activity was mostly based on the state-of-the-art hybrid access techniques specified in the Broadband Forum and a priori knowledge on some of the UAS multilink concepts developed in previous research projects. Due to its modular principles, flexible configurations, and converged core approach, the 5G NR architecture is recommended as baseline for future UAS DataLink communications studies within DroC2om and other similar research projects. Next, we have analysed the baseline radio access and radio mobility performance in typical LTE network deployments, when providing the Command and Control (C2) DataLink service to UAVs. These reference studies have been carried out via numerical simulations in site-specific, rural and urban LTE network scenarios (Fyn and Aalborg, Denmark). Furthermore, in all simulations, also the 1 The opinions expressed herein reflect the author s view only. Under no circumstances shall the SESAR Joint Undertaking be responsible for any use that may be made of the information contained herein. 4

5 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links usual terrestrial users have been taken in consideration and their performance analysed. The results clearly indicate that even in both rural and urban scenarios the downlink network traffic load, which is mostly generated by terrestrial users, is a dominant factor in the performance of the UAS DataLink services. Conversely, the UAS DataLink service can significantly degrade the uplink performance of all users in the network. Under the 3GPP C2 traffic profile, the 99.9 % reliability requirement was shown as being impossible to meet at higher UAV heights higher than m, even with very low spatial density of UAVs and in low network traffic load conditions. This result indicates that the Droc2om high traffic profile requirements will be even more challenging to meet in practice. However, for Droc2om low traffic profile the performances are expected to improve significantly and current LTE networks might be able to provide the communication link for UAS DataLink services. The first experimental results on radio mobility, performed in Urban Aalborg using connectivity provided by two different NMOs (live LTE networks), have been analysed. Like in simulations, these measurements also highlighted the difficulties in providing the 99.9 % reliability level when connected to an LTE network. However, when a dual-lte connectivity can be used where the UAV radio modem is always connected to the network with best performance our theoretical analysis shows that the 3GPP C2 traffic profile requirements could be met. Our recommendation, and plan in Workpackage 4, is to follow up on this study based on more extensive investigations to be carried out in Workpackage 5, and to develop a dual-lte connectivity framework specifically tailored for UAS DataLink services. The third part of the work focused on the evaluation of downlink and uplink radio interference mitigation mechanisms required to meet the 3GPP C2 traffic profile requirements, in both rural and urban scenarios. Techniques for both user terminal and network side have been explored. The main findings show that UAVs equipped with more advanced LTE modems, including interference cancelling receiver and/or transmit/receive beam switching capabilities, can significantly boost the UAS DataLink performance. We recommend therefore the use of these advanced LTE modems for highly reliable UAS DataLink services. On the network side, several improvements can also be implemented, especially in the area of interference coordination among the radio cells and carrier frequency re-use for UAS DataLink services. Nevertheless, these network upgrades might prove quite costly in both hardware/software cost and terrestrial subscribers radio service performance for certain MNOs, at least in regions where the density of the expected UAV subscribers is very low. Therefore, we recommend the network upgrades to be introduced in networks where there is high UAV traffic high revenue for MNO or when features are needed also for terrestrial user services, e.g. inter-cell interference coordination in dense urban area. In conclusion, the Deliverable D4.1 has addressed, from terrestrial (cellular) radio access point of view, most of the general requirements as outlined in Deliverable D2.1. Several requirements remain to be addressed in upcoming work, in the context of Deliverable D4.3 and in the conjunction with the Workpackage 3 activities. 5

6 EDITION [01.00] Table of Contents 1 Introduction Cellular radio networks DataLink performance evaluation Cellular radio mechanisms for DataLink provisioning Conclusions and recommendations References Appendix A State-of-the-art cellular radio access Uu interfaces Appendix B Performance evaluations in 3GPP Aerial Vehicle scenarios

7 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links List of Tables Table 1: Abbreviations Table 2: Terminology and definitions Table 3: Mobility simulation assumptions for site-specific Rural Fyn [20] and Urban Aalborg scenarios Table 4: Preliminary content of the cellular radio data time traces provided by Workpackage 3 for cellular radio access performance simulations in Workpackage Table 5: Preliminary content of the terrestrial-only radio access performance data time traces provided by Workpackage 4 for performance visualisation in Workpackage Table 6: General user performance requirements Table 7: Generic user functional requirements Table 8: Generic data link functional requirements Table 9: Terrestrial C2 link specific requirements Table 10: Requirements to support Multiple Operator List of Figures Figure 1: Combined cellular-satellite radio network architecture concept (based on [1]). The scope of Deliverable D4.1 is highlighted Figure 2: The 3GPP EPS elements, functions and interfaces. The functional split between E-UTRAN and EPC (core network) is also indicated Figure 3: The 3GPP 5G system architecture (non-roaming, reference point representation) Figure 4: The 3GPP E-UTRAN architecture Figure 5: The 3GPP NG-RAN architecture (standalone deployment) Figure 6: High level block diagram of the hybrid cellular-satellite DataLink solution targeted in DroC2om Figure 7: The site-specific Rural Fyn (top) and Urban Aalborg (bottom) radio network deployment layouts. Radio site locations and sector (cell) orientations are depicted Figure 8: Baseline radio performance of Aerial Vehicles in the Rural Fyn scenario Figure 9: Baseline radio mobility performance of Aerial Vehicles in the Rural Fyn scenario for two network load points (30 % for medium load 67 % for high load) Figure 10: Baseline radio performance of Terrestrial UEs in the Rural Fyn scenario for two network load points (30 % for medium load 67 % for high load). The left most bars in each plot correspond to the scenarios without AVs, i.e. with only Terrestrial UEs

8 EDITION [01.00] Figure 11: Baseline radio mobility performance of Aerial Vehicles in the Urban Aalborg scenario for two network load points (30 % for medium load 57 % for high load) and 1 % UAV penetration ratio.35 Figure 12: Baseline radio mobility performance of Aerial Vehicles in the Urban Aalborg scenario for medium network load (30 %) and 1 % or 10 % UAV penetration ratio Figure 13: Baseline radio performance of Terrestrial UEs in the Urban Aalborg scenario for two network load points (30 % for medium load 57 % for high load) and 1 % UAV penetration ratio. The left most bars in each plot correspond to the scenarios without AVs, i.e. with only Terrestrial UEs.. 37 Figure 14: Baseline radio performance of Terrestrial UEs in the Urban Aalborg scenario for medium network load points (30 %) and 1 % or 10 % UAV penetration ratio. The left most bars in each plot correspond to the scenarios without AVs, i.e. with only Terrestrial UEs Figure 15: UAV flight route at 40 m height, and radio hand-over events for test UE connected to Network 1. Only the Network 1 radio cells are depicted Figure 16: UAV flight route at 40 m height (same as in Figure 15), and radio hand-over events for test UE connected to Network 2. Only the Network 2 radio cells are depicted Figure 17: The RSRP, RSRQ and downlink packet delay KPIs recorded during the UAV flight at 40 m height. The separate results in Network 1 (blue) and Network 2 (red) depicted. The radio hand-over events, separately within each Network, are marked with green triangles Figure 18: The radio access outage levels achievable in the two separate Networks and with a theoretical dual-lte radio access scheme, during the UAV flight at 40 m height depicted in Figure 15 and Figure 16, and based on the analysis of the KPIs shown in Figure Figure 19: Antenna beam steering configurations for the drone with 2, 4 and 6 fixed beams Figure 20: Outage probability for a drone at 120 m in urban environments with and without fixed grid of beams for the medium and high network load case Figure 21: Outage probability for a drone at 120 m in urban environments with and without interference cancellation, removing the 3 potential strongest interferers completely for the medium and high network load case Figure 22: Outage probability for a drone at 120 m in urban environments with and without ICIC with 10 and 20 cells muted for the medium and high network load case Figure 23: Network beam steering concept for UAVs Figure 24: Uplink throughput for UAV (left axis) and terrestrial (right axis) users for different UAVspecific power P0 settings for the medium network load case with 1% of the users being UAVs Figure 25: Uplink throughput for UAV (left axis) and terrestrial (right axis) users for different number of beams from the UAV for the medium network load case with 1% of the users being UAVs

9 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links 1 Introduction 1.1 Purpose and Scope The target of this Deliverable is to provide 3GPP cellular 4G/5G radio concepts and radio performance evaluations for solutions supporting UAS data link connectivity. The overall framework of Workpackage 4 activities is depicted in Figure 1 (based on [1]) with the scope of Deliverable D4.1 highlighted. The work has been carried out in close collaboration and with input from Workpackage 2 and Workpackage 5 activites. The system requirements and scenarios detailed in Deliverable D2.1 [2] have been used whenever possible. The propagation models derived based on the experimental work described in Deliverable D5.1 [3] have been incorporated in the simulation tool used for the performance evaluations. Scope of D4.1 SAT RA 3GPP RAN UAV SGW Radio Radio mobility U-plane Mgmt Radio Radio mobility U-plane Mgmt Integrated data link Hybrid C/U-plane management Figure 1: Combined cellular-satellite radio network architecture concept (based on [1]). The scope of Deliverable D4.1 is highlighted. 9

10 EDITION [01.00] 1.2 Technical contributions The work documented in this Deliverable D4.1 has contributed to the following technical DroC2om areas: o 3GPP LTE and 5G radio access network concepts for UAS data link provisioning Section 2. o Methodology and extensive LTE radio access and mobility performance evaluation result for UAS data link provisioning, with in-depth analysis of potential solutions Section 3.1, Section 3.2 and Section 4.1. o Preliminary analysis of first radio mobility measurements in live LTE networks Section 3.3. o First proposals for the integrated (hybrid) SAT-3GPP LTE radio architecture Section

11 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links 1.3 Abbreviations, terminology and definitions Abbreviation 3G 3GPP 4G 5G 5GC 5G NR AERO AF AFRMS AMF ANS AS ATM ATS AUSF AV BBF BVLOS C2 (C&C) CN CM EASA D&A (DAA) DL DN DTM enodeb (enb) gnb HCPE HAG HDLGW HDLUE Explanation 3GPP UMTS 3 rd generation cellular systems 3 rd Generation Partnership Project (cellular systems) 3GPP UMTS-LTE (E-UTRAN) 4 th generation cellular systems (aka LTE) 3GPP 5 th generation cellular systems 3GPP 5G Core Network 3GPP 5 th generation New Radio cellular systems Asymmetric Extended Route Optimization Application Function (5G) Airborne Flight and Radio Management System Access and Mobility Management Function (5G) Air Navigation Services Access Stratum (communication protocol) Air Traffic Management (manned and unmanned) Air Traffic Services Authentication Server Function (5G) Aerial Vehicle(3GPP) or Drone (SJU) Broadband Forum Beyond Visual Line-Of-Sight Command and Control Core Network (3GPP) Connection Management European Aviation Safety Agency Detect and Avoid Downlink radio communication, Forward link (FWD): Network/Satellite -to- UA Data Network e.g. operator services, Internet access or 3rd party services Drone Traffic Management E-UTRAN Node B (base station) 5G Node B Hybrid-access Consumer Premises Equipment Hybrid-access Gateway Hybrid (multilink) DataLink Gateway. Same as Multi-Link Gateway (MLGW) Hybrid (multilink) DataLink User Equipment. Same as Multi-Link Adaptor (MLA) 11

12 EDITION [01.00] ICAO IP International Civil Aviation Organization Internet Protocol IPv4 IP version 4 IPv6 IP version 6 JARUS KPI L2 LA LISP LOS Joint Authorities for Rulemaking of Unmanned Systems Key Performance Indicator Layer 2 communication protocols Link adaptation (radio) A Multi-Homing and Mobility Solutions for ATN using IPv6 Radio Line-Of-Sight LTE 3GPP UMTS Long Term Evolution (Release 8-9) LTE-A, LTE-Advanced 3GPP UMTS Long Term Evolution Advanced (Release 10-15) GBR gnodeb (gnb) gnb-cu gnb-du GRE HA HAG HCPE HO IETF MAC MLA MLGW MME MPTCP NAS N3IWF NEF NG NLOS NRF Guaranteed Bit Rate Next generation NodeB (5G) gnb Central Unit gnb Distributed Unit Generic Routing Encapsulation Hybrid Access (BBF) Hybrid Access Gateway. A logical function in the operator network implementing the network side mechanisms for simultaneous use of both e.g. SAT and 3GPP access networks Hybrid Customer Premises Equipment (CPE). CPE enhanced to support the access side mechanisms for simultaneous use of both e.g. SAT and 3GPP access Radio hand-over (serving cell change) Internet Engineering Task Force Medium Access Control layer (communication protocol) MultiLink Adaptor MultiLink Gateway Mobility Management Entity (4G) Multipath TCP Non-access Stratum (communication protocol) Non-3GPP InterWorking Function (5G) Network Exposure Function (5G) Next Generation (5G) Radio Non-Line-Of-Sight NF Repository Function (5G) 12

13 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links NSSF OWD PCF PDCP P-GW PHY PiC QCI QoS Qout QUIC RAN RLC RLF RMa RTT RPAS RRC RRM SAT S(at)GW SATPL SEPP SDAP SESAR JU SFRMS S-GW SoA SMF TCP TR UA UAS UDM Network Slice Selection Function (5G) One-way delay Policy Control Function (5G) Packet Data Convergence Protocol (communication protocol, 3GPP) Packet Data Network Gateway (4G) Physical layer (communication protocol) Pilot in Command QoS Class Identifier Quality of Service (DL) Serving Signal Quality Outage Quick UPD Internet Connections Radio Access Network Radio Link Control layer (communication protocol) Radio Link Failure Rural Macro (3GPP scenario) Round Trip Time Remotely Piloted Aircraft System: Equivalent to UAS Radio Resource Control layer (communication protocol) Radio Resource Management Satellite System/Network Satellite Gateway Satellite Transparent payload (supported by Platform) Security Edge Protection Proxy (5G) Service Data Adaptation Protocol (5G) Single European Sky Air traffic management Research Joint Undertaking Satellite Flight and Radio Management System Serving Gateway (4G) State-Of-the-Art (literature, solution, concept) Session Management Function (5G) Transmission Control Protocol Technical Report Unmanned Aerial/Aircraft Unmanned Aerial/Aircraft System, including UAV, ground control, and communication link Unified Data Management (5G) 13

14 EDITION [01.00] UDP User Datagram Protocol UDR Unified Data Repository (5G) UDSF Unstructured Data Storage Function (5G) UE User Equipment (3GPP 4G/5G) UL Uplink radio communication, Reverse link: UA -to- Network/Satellite UMa Urban Macro (3GPP scenario) UPF User Plane Function (5G) U-Space See Table 2 VLOS Visual Line-Of-Sight VPN Virtual Private Network Table 1: Abbreviations Term C2, C2 DataLink, UAS DataLink C-plane Drone Hybrid Access Hybrid Access path Hybrid Access session Payload Radio adaptation Radio capacity Explanation Command and Control Link, a data link established between the remote Pilot in Command (PiC) and the vehicle it is controlling. This link is used to exchange data necessary for the Aviate, Navigate, Communicate functions of the airborne platform and is different from the Payload Communication link that is used to carry data related to the mission of the vehicle from a customer point of view. Control plane radio communication protocols; control messages, data packets used to manage the user plane (U-plane) UAV with private or commercial application, operating in the EASA Open or Specific category. The coordinated and simultaneous use of two heterogeneous access paths (e.g., LTE and SAT). Network connectivity instance between HCPE and HAG over a given access network; SAT or 3GPP. A logical construct that represents the aggregate of network connectivity for a Hybrid Access subscriber at the HAG. It represents all traffic associated with a subscriber by a given service provider, with the exception of Hybrid Access bypass traffic, and provides a context for policy enforcement. The term payload designates the equipment that is hosted on a physical aerial/airborne platform for the purpose of performing the mission. The term payload can be used in reference to a UAV Payload (i.e. the equipment on board the UAV that are used for the UAV to perform its mission, e.g. sensors or cameras used to examine a given geographical area). The term payload can be used in reference to a Satellite Payload (i.e. the equipment on board a satellite that is used for the satellite to perform its mission, e.g. a transparent signal repeater in a telecommunication satellite or an optical equipment in an earth observation satellite). Adaptation and configuration mechanisms on the PHYsical layer and Medium Access Control layer The transmission (DL and UL) radio resources available in the radio system. 14

15 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links Radio link Radio mobility U-plane U-Space Table 2: Terminology and definitions The DL or UL radio transmission link UE changing the serving radio cell (base station, enb, satellite) due to physical movement, radio channel changes, or explicit commands from the serving cell. User plane radio communication protocols; payload end-user data packets A set of new services and specific procedures designed to support safe, efficient and secure access to airspace for large number of drones. 15

16 EDITION [01.00] 2 Cellular radio networks In this section we provide a summary of the network architecture elements for LTE/4G and 5G NR which are considered relevant for the final UAS DataLink provisioning solutions targeted in the DroC2om project (Deliverable D4.3). The following description of the state-of-the art is not meant to be exhaustive, or a tutorial like description; and all the technical details can be found in the corresponding 3GPP specification documents. 2.1 State-of-the-art cellular system architecture LTE/4G: Evolved Packet System The evolution of the non-radio functionalities known under the term System Architecture Evolution (SAE), which includes the Evolved Packet Core (EPC) network, together with the Evolved UTRAN (E-UTRAN) access network, comprise the Evolved Packet System (EPS). The EPS uses the concept of end-to-end EPS bearers to route IP traffic from a gateway in the packet data network (PDN) to the user equipment (UE). An end-to-end bearer is an IP packet flow with a defined quality of service (QoS) between the gateway and the UE. The E-UTRAN and EPC together manage (set up and release) the end-to-end bearers as required by the different UE applications. The PDN gateway provides Internet access (IP connectivity) to each UE. The various elements, functions and interfaces in the EPS are depicted in Figure 2. A more detailed description of the EPS can be found in [4] [5]. E-URAN EPC HSS S6a S1-MME MME S11 PCRF Gx Rx DN LTE-Uu S1-U S5/S8 UE enodeb S-GW P-GW SGi Figure 2: The 3GPP EPS elements, functions and interfaces. The functional split between E-UTRAN and EPC (core network) is also indicated. For the purpose of the DataLink provisioning as addressed in DroC2om, here we focus the discussions on a few EPS elements only: serving gateway (S-GW), packet data gateway (P-GW) and mobility management entity (MME). While the policy control and charging rules function (PCRF) and the home subscriber server (HSS) are also needed, their functionality might not need to be adapted in order to support DataLink services. 16

17 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links We list below the potential relationship between these entities and the DataLink service. More details will likely be identified in the final DroC2om hybrid access architecture proposal(s) to be documented in Deliverable D4.3. P-GW: P-GW The PDN Gateway is responsible for IP address allocation for the UE, as well as QoS enforcement and flow-based charging according to rules from the PCRF. It is responsible for the filtering of downlink user IP packets into the different QoS-based bearers. This is performed based on Traffic Flow Templates (TFTs). The P-GW performs QoS enforcement for guaranteed bit rate (GBR) bearers. It also serves as the mobility anchor for interworking with non-3gpp technologies [...]. [4] o Managing (address allocation, address translation, and QoS enforcement) of the DataLink packets flows to/from outside the Operator s network. o Ideally the P-GW should have enough knowledge on the DataLink traffic type and requirements in order to be able to properly manage the QoS. This information can be provided by the PCRF by means of QoS authorization (QoS class and bitrates). o The P-GW (possibly complemented with required U-Space specific functionalities) will be the main DataLink interface entity to the U-Space and the UAS Connectivity Service Provider. S-GW: S-GW All user IP packets are transferred through the Serving Gateway, which serves as the local mobility anchor for the data bearers when the UE moves between enodebs. It also retains the information about the bearers when the UE is in the idle state (known as EPS Connection Management IDLE [ECM-IDLE]) and temporarily buffers downlink data while the MME initiates paging of the UE to reestablish the bearers. [4] o Maintaining the high availability of the end-to-end data bearer carrying the DataLink packets. o When multiple enodeb would be used simultaneously (multi-connectivity) to provide the DataLink the S-GW has the role of coordinating them, in addition to the direct inter-enodeb coordination (via X2). MME: MME The Mobility Management Entity (MME) is the control node that processes the signalling between the UE and the CN. The protocols running between the UE and the CN are known as the Non- Access Stratum (NAS) protocols. [4] o Establishment, maintenance and release of the bearer carrying the DataLink packets o Security and authentication functionalities, mobility in the NAS layer Interworking with non-3gpp access The EPS supports the use of non-3gpp IP access networks to access the EPC, such as WLAN or WiMax [5]. The EPS architecture presented in Figure 2 does not show the interworking with non-3gpp IP access. In order to realize the hybrid cellular-satellite access for the DataLink service, the EPC needs to be interfaced (gateway - based or application -based) with the satellite access network, ideally using one of the interworking options already defined in 3GPP [5]. The DroC2om proposal for this will be detailed in the in Deliverable D

18 EDITION [01.00] G: System architecture One representation of the current 5G System Architecture is depicted in Figure 3 [6]. Like the presentation in Section 2.1.1, here we discuss only the entities and functionalities most relevant to the DroC2om studies for UAS DataLink provisioning. AMF: Access and Mobility Management function includes the following main functionalities: o Termination of RAN CP interface (N2). o Termination of NAS (N1), NAS ciphering and integrity protection. o Registration, Connection, Reachability and Mobility management. o Access Authentication and Authorization. o Support of N2 interface with Non-3GPP InterWorking Function (N3IWF) and NAS signalling with an UE over N3IWF. o Management of mobility, authentication, and separate security context state(s) of a UE connected via non-3gpp access or connected via 3GPP and non-3gpp accesses simultaneously [7]. SMF: Session Management function includes the following main functionalities: o Session Management, e.g. Session establishment, modify and release, including tunnel maintain between UPF and AN node. o o UE IP address allocation & management (including optional Authorization). Selection and control of UP function, including controlling the UPF to proxy ARP or IPv6 Neighbour Discovery, or to forward all ARP/IPv6 Neighbour Solicitation traffic to the SMF, for Ethernet PDU Sessions. o Configures traffic steering at UPF to route traffic to proper destination. UPF: User Plane function includes the following main functionalities: o Anchor point for Intra-/Inter-RAT mobility (when applicable). o External PDU Session point of interconnect to Data Network. o Packet routing & forwarding (e.g. support of Uplink classifier to route traffic flows to an instance of a data network, support of Branching point to support multi-homed PDU session). o Packet inspection, e.g. Application detection based on service data flow template. o User Plane part of policy rule enforcement, e.g. Gating, Redirection, Traffic steering. NEF: Network Exposure function includes the following main functionalities: o 3GPP NFs expose capabilities and events to other NFs via NEF. NF exposed capabilities and events may be securely exposed for e.g. 3rd party, Application Functions, Edge Computing. o It provides a means for the Application Functions to securely provide information to 3GPP network, e.g. Expected UE Behaviour AF: The Application Function (AF) interacts with the 3GPP Core Network in order to provide services, for example to support the following: o Application influence on traffic routing o Accessing Network Exposure Function o Interacting with the Policy framework for policy control 18

19 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links N13 NSSF AUSF UDM N22 N12 N8 N10 N11 N7 AMF SMF PCF AF N5 N1 (5G NAS) N14 N15 N2 (NGAP) N4 (PFCP) UE (R)AN UPF N6 DN N3 (GTP-U) N9 Figure 3: The 3GPP 5G system architecture (non-roaming, reference point representation). Some of the key characteristics of the 5G system architecture which the DataLink service can utilize are listed below [6]: Separate the User Plane (UP) functions from the Control Plane (CP) functions, allowing independent scalability, evolution and flexible deployments e.g. centralized location or distributed (remote) location. Support concurrent access to local and centralized services. To support low latency services and access to local data networks, UP functions can be deployed close to the Access Network. Support roaming with both Home routed traffic as well as Local breakout traffic in the visited PLMN. Support a unified authentication framework. Interworking with non-3gpp access The 5G CN supports the connectivity of the UE via non-3gpp access networks, e.g. WLAN access. The 5G architecture presented in Figure 3 does not show the interworking with non-3gpp IP access (via the N3IWF) [6] [8] [7]. To realize the hybrid cellular-satellite access for the DataLink service, the 5G CN needs to be interfaced (gateway -based or application -based) with the satellite access network, ideally using one of the interworking options already defined in 3GPP [5]. The DroC2om proposal for this will be detailed in the in Deliverable D

20 EDITION [01.00] 2.2 State-of-the-art cellular radio access LTE/4G: E-UTRAN The 3GPP E-UTRAN architecture is depicted in Figure 4. The main functionalities of the E- UTRAN are listed below along with the main relationship between these and the DataLink service. Radio resource management (RRM): radio bearer control, radio admission control, radio mobility control, multi-user dynamic scheduling of the radio (time-frequency) resources to/from served UEs; this includes also all signalling and data exchange between enodeb via the X2 interface. o o The availability, reliability and throughput of the DataLink service heavily relies on the RRM functionalities, especially on the algorithms used for the multi-user scheduling of the radio (time-frequency) resources. The mobility management (UEs changing serving cells) is an important functionality, and needs to ensure always-connected DataLink service. Security: Encryption of the data transmitted over the air-interface (UE-Uu) o This functionality provides the basis of a secure (authentication and authorization) end-to-end data bearer carrying DataLink packets. Connectivity to the EPC: Signalling to MME and data bearer to S-GW o o Routing the end-to-end data bearer carrying DataLink packets. Provides mechanism for S1 mobility (between enodeb without direct X2). EPC MME/S-GW MME/S-GW E-URAN S1 S1 S1 S1 UE LTE-Uu enodeb1 X2 enodeb2 LTE-Uu UE enodeb3 LTE-Uu UE Figure 4: The 3GPP E-UTRAN architecture. 20

21 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links G: NG-RAN The 3GPP NG-RAN architecture is depicted in Figure 5. The main functionalities of the NG- RAN are listed below along with the main relationship between these and the DataLink service. Radio resource management (RRM): radio bearer control, radio admission control, radio mobility control, multi-user dynamic scheduling of the radio (time-frequency) resources to/from served UEs; this includes also all signalling and data exchange between gnb via the Xn interface and between gnb-dus belonging to the same gnb-cu. o o o The availability, reliability and throughput of the DataLink service heavily relies on the RRM functionalities, especially on the algorithms used for the multi-user scheduling of the radio (time-frequency) resources. The mobility management (UEs changing serving cells) is an important functionality, and needs to ensure always-connected DataLink service. Dual/multi-connectivity, natively supported in the NG-RAN, can ensure high DataLink reliability especially in dense urban scenarios where the gnb-cu/du configurations are more likely to be deployed. In a Non-Standalone deployment mode (LTE EPC based), a 5G UE can connect to both a LTE enb and a 5G gnb using dual-connectivity, ensuring fast switching and reduced handover delays. Security: Encryption of the data transmitted over the air-interface (5G-Uu) o This functionality provides the basis of a secure (authentication and authorization) end-to-end data bearer carrying DataLink packets. Connectivity to the 5GC (AMF/UPF): o o Routing the end-to-end data bearer carrying DataLink packets. Provides mechanism for NG mobility (between gnb without direct Xn). 5GC AMF/UPF NG-RAN NG NG NG gnb3 Xn gnb-cu UE 5G-Uu gnb1 Xn 5G-Uu gnb2 UE F1 gnb-du gnb-du 5G-Uu UE UE 21

22 EDITION [01.00] Figure 5: The 3GPP NG-RAN architecture (standalone deployment). 2.3 Preliminary proposals for integrated hybrid cellular-satellite DataLink solutions State-of-the-art hybrid access solutions Here we provide brief descriptions of the available state-of-the art (SoA) technical solutions which have potential and/ or are related to the hybrid access solutions targeted in DroC2om. Details will be provided in the follow-up Deliverables D4.2 and D4.3 on the mechanisms selected to be used in the hybrid access DroC2om concept. Mobile broadband hybrid access The Broadband Forum has specified a hybrid access network architecture, primarily used for combined 3GPP mobile and fixed broadband access [9]. There are three main transport models, as summarized below. These rely on different capabilities for the hybrid-access consumer premises equipment (HCPE), the hybrid-access gateway (HAG) and functionality required in the access network infrastructure. Layer 3 Overlay Tunnelling The connectivity between the HCPE and the HAG is established using tunnels on top of the access infrastructure. The tunnels are established between the HCPE and the HAG over each of the access paths. The HCPE is responsible for managing the tunnel (both establishment and tear down) as well as upstream forwarding decisions. The HAG is responsible for downstream forwarding decisions. The implementation itself is access network agnostic, therefore no changes to either the fixed broadband or the 3GPP access networks are necessary. Layer 3 Network-based Tunnelling The connectivity between the HCPE and the HAG is realized by making use of the native technologies in both the fixed broadband (e.g. IPoE/PPPoE) and 3GPP access networks, from HCPE to BNG and from HCPE to enodeb respectively. On setup, the network establishes the tunnels to the HAG on behalf of the subscriber s HCPE and stitches traffic from the access sessions to those tunnels, in order to reach the HAG. Each Hybrid Access path is the end-to-end path resulting from stitching the access session in the respective access network with the corresponding tunnel from the access network to the HAG. Layer 4 Multipath (Multi Path TCP) The connectivity between the HCPE and the HAG is established using a Layer 4 multipath transport service enabling IP flows to use multiple paths in the Hybrid Access path group simultaneously. As an example, a L4 multipath implementation using MPTCP sets up multiple TCP sub-flows over the different access networks and utilizes real time HCPE to HAG flow control. The 22

23 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links HCPE and HAG are responsible for managing the MPTCP paths, including establishment and tear down. Multi-path TCP [10] [11] provides an application level connectivity option using multiple TCP flows transmitted over different paths and/or access networks, thus improving the overall reliability and latency of the data connection. Generic Routing Encapsulation (GRE) GRE [12] provides a control plane solution (tunnel management, policy and traffic control) between the HCPE an HAG via extensions which enable operators to construct residential networks that are able to access the provider service through more than one hybrid access networks simultaneously in order to satisfy the higher bandwidth requirements. Locator Identity Separation Protocol (LISP) LISP [13] is a routing architecture that creates a new paradigm by splitting the device identity and its location into two different numbering spaces. This capability brings renewed scale and flexibility to the network in a single protocol, enabling the areas of mobility, scalability and security. LISP has the capability to provide a transparent multi-homing solution for the end systems which allows load sharing between the different radio technologies dependent on the available QoS. It also solves the network mobility problem of the aircraft network and together with GETVPN it provides a maintainable security solution. Asymmetric Extended Route Optimization (AERO) AERO [14] supports mobility by modelling the enterprise network as a virtual link through a process known as encapsulation. AERO is based on a Non-Broadcast, Multiple Access (NBMA) tunnel virtual link model, where all nodes appear as neighbours the same as if they were attached to the same physical link. The AERO system tracks mobile devices through control message signalling and an efficient routing system. Dynamic link selection, mobility management, quality of service (QoS) signalling and route optimization are naturally supported through dynamic neighbour cache updates, while prefix delegation (PD) is supported by the Dynamic Host Configuration Protocol for IPv6 (DHCPv6). 23

24 EDITION [01.00] Preliminary DroC2om proposals The hybrid cellular-satellite DataLink solution targeted in DroC2om has to re-use as much as possible from the SoA solutions and architectures. This is needed in order to be able to integrate the DroC2om solution into existing access networks (3GPP and satellite), without requiring excessive changes or upgrades. In Figure 6 we show the preliminary high-level block diagram of the hybrid cellular-satellite DataLink solution to be developed in DroC2om. This is based on the SoA access solutions described in Section 2.3.1, where we have replaced the fixed broadband access path with the satellite access path. Therefore, the main activity in DroC2om will focus on working out the details for the functionalities required in the Hybrid (multilink) DataLink Gateway (HDLGW) and the Hybrid (multilink) DataLink User Equipment (HDLUE) entities. These will be addressed in Deliverables D4.2 and D4.3. Figure 6: High level block diagram of the hybrid cellular-satellite DataLink solution targeted in DroC2om. 24

25 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links 3 DataLink performance evaluation 3.1 Scenarios and methodology Scenario modelling For this Deliverable D4.1 work, the exploratory scenarios described in Section 2.1 of Deliverable D2.1 [2] have been mapped to two generic performance evaluation scenarios: rural and urban, characterised by the type of terrestrial network deployments in typical rural and urban geographical areas, respectively. Furthermore, the terrestrial network models used for the analysis of these two types of deployments can be further differentiated into: 1. Regular 3GPP LTE network deployment scenarios and propagation models. These scenarios are well documented and have been used for extensive reference studies of aerial vehicles communication support in LTE, as presented in [15] [16] [17]. Annex B.1 provides the detailed description of these evaluation scenarios and the corresponding reference performance results are documented Annex B Site specific, real LTE network, deployment scenarios. These scenarios are used to establish a more realistic performance estimation for currently deployed radio access networks and user terminal configurations. The propagation models are derived either from radio measurements or adopted from corresponding 3GPP scenarios. Based on the measurement campaigns described in Deliverable D5.1 [3], the investigated site-specific deployments correspond to the typical Danish rural and urban terrestrial LTE network deployments. Section provides the detailed description of these evaluation scenarios and the corresponding reference performance results are documented in Section Evaluation methodology A preliminary report of the experimental drone measurement campaigns, and analysis of the findings, conducted in the DroC2om project, is available in Deliverable D5.1 [3]. Existing cellular LTE networks were used in the experiments in urban and rural areas. The large-scale path loss and interference characteristics of the radio channel derived in Deliverable D5.1 [3] and radio channel models from [15] [18] [19] were used for the performance evaluations in Section 3 and Section 4. The performance evaluations in this document are based on extensive system-level and mobility simulations using a dedicated and Nokia proprietary simulation environment according to the relevant 3GPP LTE radio specifications. The 3GPP C2 traffic profile is used and this can be considered as an average traffic condition for the DroC2om high traffic profile (Section of Deliverable D2.1) [2]. The reference performance results presented in Section correspond to the case when no UAV DataLink specific network or terminal modifications are assumed. In Section 4 we detail our proposals for network and terminal enhancements such that the 3GPP C2 link requirements are met [2]. 25

26 EDITION [01.00] In addition to the path loss and interference characteristics, the Deliverable 5.1 [3] also presented some very first measurements to characterise LTE radio mobility aspects for a drone connected to cellular networks in an urban scenario. These initial measurements were used for the experimental results presented in Section Evaluation results Key performance indicators The performance evaluations presented in this section are analysed in terms of the following radio performance KPIs: Average UE downlink (forward link) SINR (db), over the total simulation time (the averaging is performed in db domain) Average UE downlink (forward link) throughput (Mbps), over the total simulation time Average UE uplink (forward link) SINR (db), over the total simulation time (the averaging is performed in db domain) Average UE uplink (forward link) throughput (Mbps), over the total simulation time The average number of HOs over time per UE (HO/sec/UE), over the total simulation time The average number of RLFs over time per UE (RLF/sec/UE), over the total simulation time Average time in Qout 2 per UE (%), defined as the ratio between the total time in Qout and the total number of UEs (all cells) normalized to the total simulation time Outage probability (%), defined as the ratio between the time in Qout and the total simulation time, for each UE, averaged over all UEs (all cells) Note The average downlink UE throughput results are presented and analysed in the view of the 50 ms latency requirement corresponding to the 3GPP C2 baseline traffic profile [2]. Therefore, the downlink results using this C2 traffic model show a maximum achievable rate of 200 kbit/s corresponding to a transmission at 100 kbit/s of the C2 data packet (1250 Bytes) within 50 ms, while the C2 packet arrival rate is 100 ms. In uplink, for UAVs the C2 traffic model was not used, and the maximum data rate can be above the minimum required 200 kbit/s. 2 The Time in Qout is defined as the time interval starting when the UE s downlink channel SINR falls below -8 db until it rises above -6 db. 26

27 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links Site-specific scenarios The network deployment layouts for the site-specific scenarios investigated are depicted in Figure 7. In both cases the simulated network layouts have been extended using the wrap-around method, so the performance results are collected from an equivalent network area which is 7 times larger. The corresponding scenario modelling parameters are listed in Table 3. The aerial vehicles were deployed with uniform random spatial distribution (2-D, fixed height) with average densities of 0.1 or 1 per sector (see Table 3), which yields the spatial densities of approximately AVs/ km 2 in the Rural Fyn scenario and approximately AVs/ km 2 or 0.18 AVs/ km 2 in Urban Aalborg scenarios. Figure 7: The site-specific Rural Fyn (top) and Urban Aalborg (bottom) radio network deployment layouts. Radio site locations and sector (cell) orientations are depicted. 27

28 EDITION [01.00] Parameter Value Carrier frequency Number of sectors (cells) and geographical area ISD BS antenna height BS antenna down-tilt (mechanical + electrical) AV UE height Terrestrial UE height 1.5m AV UE velocity Terrestrial UE velocity Traffic model Number of AVs LOS/NLOS MR triggering RLF triggering Simulation time Rural Fyn: 10MHz in 800MHz band Urban Aalborg: 20MHz in 800MHz band Rural Fyn: 7*212 sectors, ~11200 km 2 Urban Aalborg: 7*300 sectors, ~11200 km 2 Rural Fyn: avg. 3000m Urban Aalborg: avg. 800m Rural Fyn: avg. 33m Urban Aalborg: avg. 30m Rural Fyn: avg. 4.6 degree Urban Aalborg: 4.8 degree 15m, 30m, 60m, 120m 30 km/h (linear flight path, at constant AV UE height) 30 km/h (linear path, at constant Terrestrial UE height) Downlink (forward link, network-to-av): - Terrestrial UEs: FTP model 3 with 0.5 MBytes buffer and variable packet interarrival time set to achieve approx. 30% or 67% in Rural Fyn, 57% in Urban Aalborg, resource utilisation (cell load). - AV UEs: Command and control traffic model with 100 kbits buffer size and 100ms arrival rate (3GPP C2 traffic profile). Uplink (reverse link, AV-to-network): - Terrestrial and AV UEs: Full buffer, time-burstiness follows downlink. In average, 10 UEs (AV & Terrestrial) per sector and: a) Reference: 0 AVs (all terrestrial UEs) b) UAV: 1% AVs per sector (0.1 AV per sector), i.e AVs/ km 2 in Rural Fyn and AVs/ km 2 in Urban Aalborg c) UAV: 10% AVs per sector (1 AV per 1 sectors) Urban Aalborg only i.e AVs/ km 2 in UMa Rural Fyn: Not used. Path loss model derived from measurements. Urban Aalborg: Dynamic; determined based on 2-D correlation distance and UE speed, for each UE towards each sector and subject to the RAN1 LOS probability channel model assumption. Path loss model specified in 3GPP RAN1. 3GPP A3 event -8dB (SINR) 400 seconds (+10 seconds warm up time) Resource allocation Terrestrial UE: Equal resources (all served UEs are scheduled) Aerial UEs: Minimum required resources Table 3: Mobility simulation assumptions for site-specific Rural Fyn [20] and Urban Aalborg scenarios. 28

29 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links Baseline performance results in site-specific scenarios In this section we present a summary of the Rural Fyn scenario performance results, extensively discussed in reference [20]. The Urban Aalborg scenario results are explained in more details. First, the site-specific scenarios have been investigated for increasing downlink traffic load, from 10 % up to around 70 %, to disclose the impact of the UAVs in various network conditions. In today s LTE networks, in rural areas the typical average traffic load is around 10 %, with peak hours (busy hours) loads around %; similarly, in urban areas the typical average load is around % with peaks around %. Therefore, the traffic load values used in our investigations should also be interpreted as potential load values in different time of the day periods, not just simply an average value during a day/week time frame. Next, for the detailed radio mobility studies, we have selected only two reference traffic load levels, representative for medium and high load conditions. These results are presented in the same format as used for the baseline 3GPP results provided in Section B.1. Baseline results for Rural Fyn scenario The baseline radio performance results versus the network traffic load are presented in Figure 8, for different UAV flight heights. These results clearly highlight the impact of traffic load (generated by terrestrial UEs) on the selected UAV s radio KPIs: DL SINR, DL throughput and outage. The average traffic load levels used in the mobility performance studies have been selected as follows: 30% for medium load 67 % for high load. The UAV penetration was 1 % (1 AV per 10 sectors). The baseline mobility performance results are presented in Figure 9. Figure 10 shows the corresponding radio performance of the terrestrial UEs, i.e. under the same load conditions, UAV penetration and set of UAV heights. 29

30 EDITION [01.00] Figure 8: Baseline radio performance of Aerial Vehicles in the Rural Fyn scenario. 30

31 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links Figure 9: Baseline radio mobility performance of Aerial Vehicles in the Rural Fyn scenario for two network load points (30 % for medium load 67 % for high load). 31

32 EDITION [01.00] No AV No AV No AV Figure 10: Baseline radio performance of Terrestrial UEs in the Rural Fyn scenario for two network load points (30 % for medium load 67 % for high load). The left most bars in each plot correspond to the scenarios without AVs, i.e. with only Terrestrial UEs. 32

33 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links Main conclusions for baseline Rural Fyn scenario Average UAV DL SINR and Throughput o o In medium traffic load conditions, these KPIs are impacted by the UAV flight height; at heights above 60 m the target average throughput of 200 kbits/ss cannot be reached due to high downlink radio interference. In high traffic load conditions, these KPIs are significantly impacted by the UAV flight height; at any heights above 15 m the target average throughput of 200 kbits/s cannot be reached due to very high radio interference. Average UAV UL SINR and Throughput o In both medium and high traffic load conditions, this KPIs are impacted by the UAV flight height; however, due to the low number of the UAVs, at any heights the target average throughput of 200 Kbps can easily be achieved. The outage probability is significantly increased for UAV flight heights above 15 m, and strongly depends on the traffic load conditions; the 99.9 % radio connectivity availability cannot be reached, regardless of the UAV flight height, even in the medium traffic load scenario. The downlink performance (throughput and outage) of the terrestrial UEs is not significantly impacted by the presence of the UAVs. The uplink throughput performance of the terrestrial UEs in medium traffic load conditions decreases significantly for UAV flight heights above 15 m. 33

34 EDITION [01.00] Baseline radio mobility results for Urban Aalborg scenario The Rural Fyn results have clearly highlighted the impact of traffic load (generated by terrestrial UEs) on the selected UAV s radio KPIs (Figure 8) even at very low UAV penetration ratio of 1 % (1 AV per 10 sectors). Thus, for the Urban Aalborg scenario, we only used two representative network traffic load levels 30 % for medium load 57 % for high load combined (partly) with two cases of UAV penetration ratios: 1 % (1 AV per 10 sectors) and 10 % (1 AV per 1 sectors). The average 57 % load level, for the high load case, was set lower compared to the 67 % high load case in the Rural Fyn scenario. This selection was made on the rationale that in a denser radio access network, such as the Urban Aalborg, lower traffic load levels are sufficient to generate critically high interference levels; thus, there was no need to investigate higher load levels, when a critical operating point was achieved already at 57 % load. The baseline mobility performance results for AVs are presented in Figure 11 and Figure 12; Figure 13 and Figure 14 show the corresponding radio performance of the terrestrial UEs, i.e. under the same load conditions, UAV penetration and set of UAV heights. 34

35 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links Figure 11: Baseline radio mobility performance of Aerial Vehicles in the Urban Aalborg scenario for two network load points (30 % for medium load 57 % for high load) and 1 % UAV penetration ratio. 35

36 EDITION [01.00] Figure 12: Baseline radio mobility performance of Aerial Vehicles in the Urban Aalborg scenario for medium network load (30 %) and 1 % or 10 % UAV penetration ratio. 36

37 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links No AV No AV No AV Figure 13: Baseline radio performance of Terrestrial UEs in the Urban Aalborg scenario for two network load points (30 % for medium load 57 % for high load) and 1 % UAV penetration ratio. The left most bars in each plot correspond to the scenarios without AVs, i.e. with only Terrestrial UEs. 37

38 EDITION [01.00] No AV No AV No AV Figure 14: Baseline radio performance of Terrestrial UEs in the Urban Aalborg scenario for medium network load points (30 %) and 1 % or 10 % UAV penetration ratio. The left most bars in each plot correspond to the scenarios without AVs, i.e. with only Terrestrial UEs. 38

39 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links Main conclusions for Urban Aalborg scenario Average UAV DL SINR and Throughput o o o In medium traffic load conditions, these KPIs are impacted by the UAV flight height; at heights above 30 m the target average throughput of 200 kbits/scannot be reached due to high downlink radio interference. In high traffic load conditions, these KPIs are significantly impacted by the UAV flight height; at any UAV heights above 15 m the target average throughput of 200 kbits/s cannot be reached due to very high radio interference. The penetration ratio of the UAVs does not significantly impact these KPIs Average UAV UL SINR and Throughput o In both medium and high traffic load conditions, this KPIs are impacted by the UAV flight height; however, due to the low number of the UAVs, even with 10% penetration ratio, at any UAV heights the target average throughput of 200 kbit/s can easily be achieved. The outage probability is significantly increased for UAV flight heights above 15 m, and strongly depends on the traffic load conditions; the 99.9 % radio connectivity availability cannot be reached, regardless of the UAV flight height, even in the medium traffic load scenario and low UAV penetration ratio. The downlink performance (throughput and outage) of the terrestrial UEs is not significantly impacted by the presence of the UAVs at low penetration ratio of 1%; however, when the number of UAVs is increased, the downlink performance of the terrestrial UEs is slightly increased as well. The uplink throughput performance of the terrestrial UEs decreases for UAV flight heights above 15 m; the uplink average throughput of the terrestrial UE decreases significantly with increased penetration ratio of the UAVs. 39

40 EDITION [01.00] Baseline performance results in 3GPP scenarios In this section we re-cap the main findings from the studies performed using the 3GPP Rural Macro and Urban Macro deployment scenarios. Annex B.1 provides the detailed description of these evaluation scenarios and the corresponding reference performance results are documented in detail in Annex B.2. Main conclusions for baseline 3GPP Rural Macro scenario The average UAV DL SINR and Throughput are significantly impacted by the UAV flight height; at heights above 50 m the target average throughput of 200 kbits/s cannot be reached due to very high downlink radio interference. The average UAV UL SINR and Throughput are significantly impacted by the UAV flight height; at heights above 100 m the target average throughput of 200 kbits/s cannot be reached due to very high uplink radio interference. For the high UAV flight speeds of 160 km/h, the increased downlink radio interference also impacts the mobility performance KPIs, and significantly increased number of RLF is observed at UAV flight heights above 50 m. The outage probability is significantly increased for UAV flight heights above 20 m, and strongly depends also on the UAV flight speed; the 99.9 % radio connectivity availability cannot be reached, regardless of the UAV flight height. The penetration of UAVs (1 or 5 per cell) has minor impact on the downlink/uplink radio performance results; this is due to the relatively high(er) traffic load conditions generated by the terrestrial UEs. The downlink performance (throughput and outage) of the terrestrial UEs is not significantly impacted by the presence of the UAVs. The uplink throughput performance of the terrestrial UEs decreases for higher number for UAVs and UAV flight heights above 20 m. Main conclusions for baseline 3GPP Urban Macro scenario The average UE DL SINR and Throughput are significantly impacted by the UAV flight height; at heights above 20 m the target average throughput of 200 kbits/s cannot be reached due to very high radio interference. The average UE UL SINR and Throughput are significantly impacted by the UAV flight height; at heights above 20 m the target average throughput of 200 kbits/s cannot be reached due to very high uplink radio interference. For the high UAV flight speeds of 160 km/h, the increased radio interference also impacts the mobility performance KPIs, and significantly increased number of RLF is observed at UAV flight heights above 20 m. 40

41 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links The outage probability is significantly increased for UAV flight heights above 20 m, and strongly depends also on the UAV flight speed; the 99.9 % radio connectivity availability cannot be reached, regardless of the UAV flight height. The penetration of UAVs (1 or 5 per cell) has medium impact on the downlink/uplink radio performance results; this is likely due to the relatively high(er) traffic load conditions generated by the terrestrial UEs. The downlink performance (throughput and outage) of the terrestrial UEs is not significantly impacted by the presence of the UAVs. The uplink throughput performance of the terrestrial UEs is decreases for higher number for UAVs and UAV flight heights above 20 m. 41

42 EDITION [01.00] 3.3 First experimental results The radio mobility experiments performed in Workpackage 5 and described in Deliverable D5.1 [3] yielded a few early results which are documented in this section. The target is to start quantifying the practically achievable radio access reliability level 99.9 % with delays below 50 ms for the C2 link [2] when using current LTE networks for the C2 communications. These results and observations will be further refined and updated based on the new experimental campaign planed within the Workpackage 5 activities. Figure 15 and Figure 16 show the test UAV flight map (route), at 40 m height, along with the LTE radio cells in the two different MNOs, Network 1 and Network 2, which have been measured simultaneously. The radio hand-over events, separately within each Network, are marked in these figures with green triangles. In Figure 17 we show the recorded traces for the RSRP, RSRQ and downlink packet delay KPIs, during the UAV flight at 40 m height, in the two networks. We have performed a preliminary analysis of a dual-lte radio access mechanism. Figure 18 shows the achieved average outage levels in the two separate Networks and when using the dual-lte radio access. Observations The average RSRP levels in the two networks are significantly different, with 20 db higher average values in Network 1. The average RSRQ levels in the two Networks are not very much different (3 db difference only). However, the fluctuations are more pronounced in Network 1, where the probability to have RSRQ levels below -20 db is approximately 40 times higher compared to Network 2. The average DL packet delays are significantly different in the two Networks. In Network 1 the probability to have delays above 50 ms is approximately 15 times higher compared to Network 2. The preliminary analysis indicates that a dual-lte access mechanism can significantly reduce the downlink packet delays, and achieve the target reliability of 99.9 % probability for packet delays below 50 ms. 42

43 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links Radio hand-over events Flight path LTE cells in Network 1 Figure 15: UAV flight route at 40 m height, and radio hand-over events for test UE connected to Network 1. Only the Network 1 radio cells are depicted. Radio hand-over events LTE cells in Network 2 Figure 16: UAV flight route at 40 m height (same as in Figure 15), and radio hand-over events for test UE connected to Network 2. Only the Network 2 radio cells are depicted. 43

44 EDITION [01.00] Average = -71 Average = -92 dbm Average = -11 Average = -14 Figure 17: The RSRP, RSRQ and downlink packet delay KPIs recorded during the UAV flight at 40 m height. The separate results in Network 1 (blue) and Network 2 (red) depicted. The radio hand-over events, separately within each Network, are marked with green triangles. 11.5% 1.5% 0.015% Figure 18: The radio access outage levels achievable in the two separate Networks and with a theoretical dual-lte radio access scheme, during the UAV flight at 40 m height depicted in Figure 15 and Figure 16, and based on the analysis of the KPIs shown in Figure

45 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links 3.4 Performance models to be used in WP3 In this Section we provide the first description of the planned interaction between Workpackage 3 and Workpackage 4 activities. We describe here the preliminary content of the data exchange, for cellular radio access performance evaluation and visualisation [21]. In Deliverable D4.2 a similar description will be provided for satellite-only radio access evaluations. The details of this data exchange will be refined iteratively, based on the on-going development of the simulation environment in Workpackage 3 and the hybrid access solution developments in Workpackage 4. Data flow from Workpackage 3 to Workpackage 4 In Workpackage 3, radio (channel) data time traces are to be generated based on the detailed radio propagation models implemented in the simulation environment described in Deliverable D3.1 The radio data time traces are provided as input to Workpackage 4 performance simulations. Cellular -only radio data time traces o The preliminary content of the cellular radio data time trace file is outlined in Table 4. Satellite -only radio data time traces Data fields Time step UAV coordinates (X,Y,Z) All enbs: Total Path Gain list Description Time resolution of the data included in the trace file 3-D coordinates of the UAV The total path gains between the UAV and all (or a subset potentially within certain range only. TBD) cells (enbs), including antenna gains, cable losses and terminal losses All enbs: ID list The list of all cell IDs (potentially within certain range only. TBD) which are detected at the UAV with an RSRP above a certain threshold All enbs, Terrestrial traffic load: Downlink list The DL traffic load generated by terrestrial users, corresponding to the enb list specified All enbs, Terrestrial traffic load: Uplink list The UL traffic load generated by terrestrial users, corresponding to the enb list specified Table 4: Preliminary content of the cellular radio data time traces provided by Workpackage 3 for cellular radio access performance simulations in Workpackage 4. 45

46 EDITION [01.00] Data flow from Workpackage 4 to Workpackage 3 In Workpackage 4, the radio performance simulations are performed based on the radio data traces from Workpackage 3 and the specific radio access models (terrestrial and satellite) developed in Workpackage 4. The radio performance data traces are provided as input to the final Workpackage 3 simulations and visualisation (Deliverable D3.3). Cellular -only radio access performance o The preliminary content of the cellular-only radio performance data time trace files is outlined in Table 5. Satellite -only radio access performance Hybrid cellular-satellite radio access performance Data fields Time step UAV coordinates (X,Y,Z) Description Time resolution of the data included in the trace file 3-D coordinates of the UAV Serving enb: ID The identification (within the simulation environment) of the currently serving enb Throughput: Downlink UAV Forward link (network-to-uav) throughput for the serving enb link. Set to 0 in time steps when there is no data to be received, according to the traffic model Throughput: Uplink UAV Reverse link (UAV-to-network) throughput for the serving enb link. Set to 0 in time steps when there is no data to be transmitted, according to the traffic model Reliability/availability KPI: Downlink Uplink The main radio performance KPI to be visualized in the tool developed in Workpackage 3. TBD. Table 5: Preliminary content of the terrestrial-only radio access performance data time traces provided by Workpackage 4 for performance visualisation in Workpackage 3. 46

47 DROC2OM D4.1 Cellular LTE/5G system concepts to provide optimal support for both terrestrial communications and high reliability UAS data links 4 Cellular radio mechanisms for DataLink provisioning 4.1 Proposed concepts This section contains the enhancements which can be made to cellular networks to enhance their handling of UAVs, addressing some of the issues mentioned in the previous section Downlink In the downlink the interference is coming from the other base stations and the amount of impact depends on the load as was shown in the previous chapter. In this section we present a number of potential solutions to the downlink interference problem. The can be split into 2 categories: 1) UAV based enhancements and 2) network based enhancements and the different solutions are described in the following subsections. Beam selection at the UAV Antenna selection with two or more antenna elements can be equivalent to a very simple beam selection when the antennas are placed on the drone at the right spacing and orientations. It is easy to increase the number of beams to four or six by adding additional directional antennas antenna elements, as depicted in Figure 19. The modeled beam patterns provide +6.6 dbi gain in the main direction and 13 db front-to-sidelobe attenuation, which can be considered to account for the non-ideal shape of the beams. Figure 19: Antenna beam steering configurations for the drone with 2, 4 and 6 fixed beams The receiver simply picks the beam direction with the best signal quality (RSRP or RSRQ) without adjusting the orientation of the drone. By doing so, the amount of interference received in the downlink is limited to the beam width of the beam, leading to a reduced overall outage as can be seen in Figure 6 for beam steering with different number of beams for the urban environment, which was described in the previous chapter. With 6 beams the achieved reliability is higher than the target 99.9%, even in the high load case. 47