Technical White Paper

Integrated Access and BackhaulJune 2020

Contents

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Introduction

IAB Use Cases

Improvements of Signal QualityFilling Coverage Holes in NLOS SituationsVehicular Connectivity

IAB Technology

Architecture OverviewTopologiesResource Allocation MethodologiesBackhaul Adaptation Protocol LayerIAB-specific Procedures & Configurations

IAB Deployments

Key ConsiderationsComputer Analysis – Houston Case

IAB in 3GPP Standards

Summary

Abbreviations

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List of Figures

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Backhaul replacement by IABRF repeater versus IAB solutionSignal quality improvement using IAB-nodeCoverage hole fillingVehicular networks using IABIAB architectureIAB topologies: (a) IAB-node using SA mode with 5GC; (b) IAB-node using EN-DCTime division multiplexingFrequency division multiplexingSpace division multiplexingFull duplexAn example of many-to-one mapping between UE bearers and RLC-channelExamples of route-redundancyCase study scenariosImpact of LOS between IAB-donor and IAB-nodeFigure 16. Impact of distance between IAB-donor and IAB-nodeSimulation results based on the ray-tracing modelIAB timeline in 3GPP RAN

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As an alternative solution for expanding coverage, the RF repeater is a decent but limited solution, due to the limitations posed by the physical properties of mmWave frequencies. As an example, if a repeater does not support beamforming technology, the coverage of the repeater is rendered severely short because of the large path-loss that the mmWave faces. To overcome such characteristic of the mmWave, beamforming technology may be applied. However, the resulting beam of the RF repeater is not adaptive and its beamwidth is too narrow to cover the wide range of angle that is required on commercial sites. Since adaptive beamforming technology is applied to IAB, longer distance and wider range coverage standout as characteristics for IAB products when compared to RF repeaters.

IntroductionLeveraging IAB for Flexible and Cost-effective 5G DeploymentsIntegrated Access and Backhaul (IAB) is a promising solution for the successful adoption of 5G. The key concept behind IAB is in reusing the existing 5G framework for both access link and backhaul. In general, the IAB solution operates on the mmWave spectrum as a way to obtain and utilize sufficient spectrum capacity. This type of solution allows the operator to improve coverage by installing denser networks, without having to lay fiber – an option that is both costly and difficult, not to mention, nearly impossible under certain circumstances. As such, IAB facilitates and reduces the cost of even the densest deployment, as well as, improving cellular coverage.

IAB for mmWave is being introduced in the Release 16 of the 3GPP standards, as a means to provide a solution that meets the 5G backhaul requirements. A key benefit of utilizing the mmWave in a wireless backhaul is reaching data rates on the order of Gigabits per second. Moreover, mmWave is the logical resource to utilize, as the spectrum is currently available for and being used by to operators to operate their 5G services.

An indispensable part of the IAB solution is resource division. There are a number of ways to separate the resources used for backhaul and access, namely time division, frequency division, space division or full duplex. The usage of a wireless backhaul allows for strategic placement of base stations to eradicate coverage holes in areas with limited cellular coverage.

Figure 1. Backhaul replacement by IAB

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Figure 2. RF repeater versus IAB solution

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As addressed previously, IAB is a powerful solution compared to alternatives such as fiber and also provides a substantial cost reduction.

•　5G roll-out, especially with mmWave, requires higher deployment density.-　In urban areas, where dark fibers are available, OPEX due to backhaul lease will be increased.-　In rural areas, where dark fibers are not available, CAPEX/OPEX will be increased even more.

•　IAB can provide backhaul link without fiber.-　If IAB is deployed in an in-band manner, the same spectrum can be reused for both access and backhaul, thereby removing

the need for additional spectrum licenses for the wireless backhaul. (Deployment in out-of-band is also available as an optionfor increased throughput and less SW complexity.)

-　Since mmWave has a large bandwidth, IAB can provide the high throughput that the wireless backhaul needs by using one of the multiplexing methods (time, frequency, space division or full duplex).

-　By utilizing IAB as a wireless backhaul, operators can expect faster network deployment or time to market when compared to wired backhaul.

IAB Use CasesImprovements of Signal Quality

When an operator desires to dramatically enhance its network capacity and deliver unprecedented data rate to its users, superimposing mmWave 5G small cells over a macro cell is arguably the best deployment solution. In general, to achieve this, the installation of fiber optics for the backhaul, which can become costly for the operator, is required. IAB, as an alternative to the fiber option, allows the operator to achieve the same feat at a lower cost.

In turn, the newly added cells (shown in figure 3) then increase the signal strength under a given coverage and improve the overall user experience.

Figure 3. Signal quality improvement using IAB-node

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Filling Coverage Holes in NLOS SituationsThe radio signals of 5G networks using high frequency bands propagate straight with very little diffraction. Due to this physical property, coverage holes emerge in regions where signal from cell sites does not reach. This is where IAB comes in handy, by adding a new cell and filling the coverage hole, often at smaller cost than that of leasing a fiber. This use case is depicted in figure 4.

IAB can also be used to extend coverage into indoor areas where the signal does not reach due to the high penetration loss. To achieve this, an IAB-node must be installed so that it is exposed both to the indoors and outdoors. This implementation results in extended coverage through an IAB-node, without the need of laying cables throughout a building.

Vehicular ConnectivityAnother use case where IAB can help operators reduce the cost is vehicular networks. As represented in figure 5, each of the cars and buses are connected to one of the base stations that are deployed along the road. By applying IAB-nodes, appropriate signal can be relayed to the base station near a vehicle through the multi-hop wireless backhaul connection. This is to say that only the donor nodes need fiber to the wired network and the cost for extending coverage along the road is significantly reduced.

Figure 5. Vehicular networks using IAB

Figure 4. Coverage hole filling

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Figure 6. IAB architecture

IAB TechnologyArchitecture OverviewThe following figure 6 shows the IAB architecture and interfaces between Network Entities (NEs).

IAB functionality requires two new NEs, an IAB-donor and an IAB-node, as well as, an interface F1 . (A description for each entity and interface follows in the next sections.) These new NEs are comprise of a Centralized Unit (CU), Distributed Unit (DU), or Mobile Termination (MT).

IAB-donorAn IAB-donor is a gNB that provides network access to UEs via a network of backhaul and access links and consists of an IAB-donor-CU and one or more IAB-donor-DUs. IAB-donor-CU is the gNB-CU of an IAB-donor, terminating the F1 interface towards IAB-nodes and IAB-donor-DU. IAB-donor-DU is the gNB-DU of an IAB-donor, hosting the IAB Backhaul Adaptation Protocol (BAP) layer, providing wireless backhaul to IAB-nodes. In case of control plane and user plane separation (i.e. separation of gNB-CU-CP and gNB-CU-UP), the IAB-donor may consist of an IAB-donor-CU-CP, multiple IAB-donor-CU-UPs, and multiple IAB-donor-DUs. The IAB-donor-CU and IAB-DU communicate with each other via the F1 interface. The IAB-donor connects to the IAB-node using the 5G New Radio (NR) access interface and is connected to the Core Network. All functions specified for a gNB-DU are equally applicable for an IAB-donor-DU and all functions specified for a gNB-CU are equally applicable for an IAB-donor-CU.

IAB-nodeThe IAB-node connects to an upstream IAB-node or an IAB-donor-DU via a subset of the UE functionalities of the NR Uu interface (referred to as IAB-MT function of IAB-node). The IAB-node provides wireless backhaul for the downstream IAB-nodes and wireless access to UEs via the network functionalities of the NR Uu interface (referred to as DU function of IAB-node). IAB-nodes can be cascaded, as shown in the figure 6. If the number of cascading IAB-nodes increases, the end-to-end latency increases, scheduling to satisfy QoS becomes complicated, and complexity of route management increases. The IAB-node connects to the IAB-donor or the upstream IAB-node via MT, using the 5G NR radio interface. The IAB-node connects to downstream IAB-nodes via DU, using the 5G NR radio interface, when multiple hops are needed. Hop-by-hop flow control may also be required together with end-to-end congestion handling. All functions specified for a gNB-DU are equally applied for an IAB-node-DU and all functions specified for the UE context are also employed in managing the context of IAB-MT functionality.

F1 InterfaceThe traffic from an IAB-node to an IAB-donor-CU is transported via the F1 interface, vice versa, and may pass through optional intermediate IAB-node(s) in case of multi-hop scenarios. The existing 3GPP F1 interface has been enhanced to support IAB functionality. Procedures to establish and release links between IAB-node and IAB-donor and between different IAB-nodes have been defined in Release 16.

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IAB in SA and NSA The IAB-node can access a network using either Stand-Alone (SA) or Non-Stand-Alone (NSA) modes. In NSA mode, E-UTRA-NR Dual Connectivity (EN-DC) is used. In EN-DC, the IAB-node also connects via E-UTRA to a MeNB, and the IAB-donor terminates X2 as SgNB. These two topologies are shown in the figure 7. The standards allow several IAB-nodes to be cascaded.

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Figure 7. IAB topologies: (a) IAB-node using SA mode with 5GC; (b) IAB-node using EN-DC

(a) IAB-node using SA mode with 5GC (b) IAB-node using EN-DC

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Frequency Division MultiplexingIn a Frequency Division Multiplexing (FDM) solution, the access and backhaul links use different frequency resources in order to avoid interference between backhaul and access links. In this case, IAB-DU and IAB-MT within an IAB-node can transmit and receive radio signals simultaneously, as long as both transmission and reception occur in different frequency resources. Then, IAB-node can have the same latency of IAB-donor unlike TDM. However, there may be still inefficient resource utilization since IAB-MT/IAB-DU within the IAB-node can only receive or transmit in its designated frequency resources. Therefore, it is necessary to divide and allocate the frequency resources between the backhaul and access links appropriately to match resource conditions of each link. Figure 9 below shows an example where the backhaul and access links are allocated in the different frequency resources.

Figure 9. Frequency division multiplexing

Resource Allocation MethodologiesThe following sections describe various types of resource division methods between backhaul and access links. For each method, factors that may affect an IAB’s performance will also be discussed.

Time Division MultiplexingIn a Time Division Multiplexing (TDM) solution, backhaul and access links exploit different time resources to avoid interference between links. In this case, IAB-MT is not allowed to transmit or receive radio signals while the corresponding IAB-DU transmits or receives radio signals, and vice versa. In this regard, IAB-node may have longer latency and/or inefficient resource utilization compared IAB-donor, which does not include IAB-MT. Therefore, it is necessary to divide and allocate time resources according to the resource availability of each link are necessary. Figure 8 below shows one example where radio resources are allocated evenly for the backhaul and access links in the time domain. Note that the grey box represents a downlink (DL) slot, and the blue box represents an uplink (UL) slot.

Figure 8. Time division multiplexing

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Full DuplexIn a full duplex solution, similar to the SDM, backhaul and access links utilize different space resources as to minimize interference between each other. However, in contrast to the SDM, the full duplex method allows the IAB-node to simultaneously transmit and receive signals using the same time and frequency resources. For this to be possible, “self-interference” power due to the IAB-DU transmission should be much lower than the signal power received by the IAB-MT from the IAB-Donor. To mitigate self-interference, the IAB-DU and IAB-MT within an IAB-node must be spatially isolated as to acquire the desired SINR and/or the IAB-node must possess the capability to remove “self-interference” between IAB-DU transmission and IAB-MT reception, vice versa. Figure 11 shows an example where radio resources are divided into the backhaul and access links in the space domain. Here, it is assumed that IAB-node has the capability to remove “self-interference”. Unlike the SDM, both the downlinks of the access and backhaul (and both the uplinks of the access and backhaul) simultaneously transmit signals.

Figure 10. Space division multiplexing

Space Division MultiplexingIn a Space Division Multiplexing (SDM) solution, backhaul and access links exploit different space resources to minimize interference between each other. Therefore, this allows the simultaneous transmission (or reception) of an IAB-node (IAB-DU, IAB-MT) under the same time and frequency resource, as long as the space separation is enough to guarantee minimum interference between the simultaneous transmissions (or receptions). Here, the space separation can be achieved by setting IAB-DU and IAB-MT to have opposite beam directions each other as possible. However, in cases where space separation alone may not be sufficient to compensate for the interference that may occur during simultaneous transmission (or reception), SDM is not a feasible option. Instead, either TDM or FDM should be used. Figure 10 shows an example of SDM in which the IAB-DU and IAB-MT are simultaneously receiving or transmitting signal using the same time and frequency resource.

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•　Routing delivers a packet to a destination node by selecting the next backhaul link from the multiple backhaul links.•　"Destination IAB-node/IAB-donor-DU address" and "Specific path identifier" (carried in the BAP) are used for routing at the BAP layer. •　"Destination IAB-node/IAB-donor-DU address" and/or "Specific path identifier" are unique within an IAB-donor-CU.•　Load balancing by routing by IAB-donor-CU is possible.•　Local selection of path/route is done at link failure.

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Figure 13. Examples of route-redundancy

Figure 12. An example of mapping between UE bearers and RLC-channel

Backhaul Adaptation Protocol LayerAn IAB-DU connects to the CU of an IAB-donor using the F1 interface. A BAP layer has been added above the RLC layer in order to include routing information and allow for hop-by-hop forwarding. The BAP layer supports the functionality of bearer mapping and routing.

Bearer Mapping

•　For the user plane, the IAB-node maps a UE bearer to a backhaul link RLC channel per the UE bearer's purpose (not per UE bearer) as shown in figure 12.

•　Control planes from UEs and F1-C messages from the IAB-DU are mapped to IAB-MT F1-C messages.

IAB-donor IAB-node

RLC-channel 3: UE bearers for web-browsing

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IAB-specific Procedures & ConfigurationsInitial Cell Search and Random Access ProcedureAn IAB-MT uses the same physical channels and procedures that a UE uses in a normal access procedure. For initial cell search, it was defined that IAB-MT exploits the same Synchronization Signal Block (SSB), but with 160 ms periodicity for SSB reception in 3GPP standards. For random access, additional Random Access Channel (RACH) configurations were defined for IAB-MTs. Especially, compared to the access UE’s RACH, IAB-specific frame/slot offset and periodicity extension of RACH Occasions (RO) were introduced.

Inter-IAB-node Discovery and MeasurementsEach IAB-node needs to discover and monitor its surrounding IAB-nodes maintaining back-up backhaul links, in the case of a backhaul link failure. This in turn means that an inter-IAB discovery signal is supported to measure received signal quality from neighboring IAB-nodes. SSB is the most suitable reference signal for this purpose, since it is periodically transmitted and beam sweeping mechanism is applied. SSB Transmission Configuration (STC) and SSB Measurement Timing Configuration (SMTC) are configured for IAB-node discovery and measurements.

Resource Configurations Resource configurations for IAB-MT are almost identical to that of a normal UE. The only difference is that UL-Flexible-DL as a new slot format is introduced to enable better support of simultaneous transmissions and receptions between the IAB-MT and the IAB-DU. In addition, new resource configuration is introduced for the IAB-DU to allow communication with other IAB-nodes and access UEs.

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Figure 14. Case study scenarios

IAB DeploymentsKey Considerations

As discussed in previous sections, IAB is a more feasible alternative in terms of cost and time consuming rather than deploying a wired backhaul further. Moreover, IAB can provide longer coverage and higher throughput compared to the baseline case where only a single cell is deployed. Above the 6 GHz band (i.e. mmWave), IAB coverage is better than RF repeater due to the beam sweeping that is available in the access link of the IAB.

There are several factors that may affect IAB’s performance. To reap the best performances of an IAB, IAB-node should be installed in proper locations, taking into account the factors below:

•　LOS between an IAB-donor and an IAB-node•　Distance between IAB-donor and IAB-node

The following sections discuss these factors in more details.

Assumptions for IAB Performance Evaluation•　Single UE in the area•　Baseline

- One cell by gNB, see figure 14.- UE is served by gNB.- Cell 1 uses 100 % of DL resources.

•　IAB- Two cells in total, one by IAB-donor and one by IAB-node.- When UE is in cell 1, it is served by IAB-donor, and when UE is in cell 2, it is served by the IAB-node- In-band configuration: access and backhaul transmitted in the same band.- TDM resource allocation, as discussed in previous section, with resources allocated as follows:

●�

○　When the UE is in cell 1, cell 1 uses 100 % of DL resources.○　When the UE is in cell 2, cell 1 and cell 2 uses 50 % of DL resources, respectively.

•　Metric of interest (Throughput): Single UE DL throughput as a percentage of UE peak throughput

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Figure 15. Impact of LOS between IAB-donor and IAB-node

Importance of Line of Sight for IAB DeploymentsTo investigate the impact of Line of Sight (LOS) between IAB-donor and IAB-node, UE throughputs for LOS and NLOS between them are compared according to d (distance between IAB-donor and UE), see figure 15. For this comparison, NLOS is assumed between UE and IAB-donor and between UE and IAB-node.

When distance between IAB-donor and UE is small, UE has high throughput. As the distance increases, the throughput falls gradually. However, if the distance increases further, the UE comes under the coverage of the IAB-node and throughput rises higher again. This rise in throughput is more for LOS and smaller for NLOS. That is, if LOS is secured between IAB-donor and IAB-node, throughput is increased significantly for a UE, which is served by the IAB-node. However, if LOS is not secured, throughput gain is marginal for a UE close to the IAB-node, compared to the baseline which is shown in figure 14 (a). This is because throughput of the UE (served by the IAB-node) is limited by backhaul link (between IAB-donor and IAB-node) as well as access link (between IAB-node and UE). Therefore, it is recommended to secure LOS between IAB-donor and IAB-node.

Figure 16. Impact of distance between IAB-donor and IAB-node

Distance Aspects for IAB DeploymentsAssuming that the IAB-node and IAB-donor have a LOS secured, the distance with which the IAB-donor and the IAB-node can be placed apart, depends on the quality of network that the operators wishes to achieve. To illustrate this idea, figure 16 shows the change in a UE’s throughput as it moves away from the IAB-donor to the IAB-node. Let’s assume that the desirable DL throughput for a single UE at the edge of a cell is at least 20 % of the peak throughput. In order to guarantee such rates, it is recommended that an IAB-node be deployed at IAB position 1. On the other hand, if the operator desires to provide only the minimum service, thereby allowing DL throughput for a single UE to drop below the 20 % threshold, installing an IAB-node at IAB position 2 will suffice. However, the maximum distance between the IAB-donor and the IAB-node will be restricted by RACH channel and a guard period.

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Figure 17. Simulation results based on the ray tracing model

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Computer Analysis - Houston Case

This chapter introduces analysis results from the system-level computer simulation, showing the benefits of an IAB deployment, compared to a gNB-only deployment. As previously described, IAB is suitable for areas where fiber installation is difficult or impossible. Consider the following situation: a gNB installed in an area with many buildings of similar height to cover a relatively small area. Here, users experience poor quality of service due to abundance of buildings and trees of similar height. As one might expect, IAB can be very effective in this situation where a RF repeater is inadequate because of its short distance characteristic, as shown in figure 2.

This simulation assumes the following environment:A single gNB site and 18 distributed outdoor UEs are installed and used, respectively, within the area of 320m x 580m in Houston, Texas, USA. The downlink throughput performance of both cases (with and without IAB) are calculated. For accurate channel modeling, ray tracing is performed according to the map information, such as terrain, building, trees, utility pole, and light pole. The height of local buildings in the area is around 5 meters. The height of gNB antenna and UEs are 16 meters and 3 meters, respectively. Simulation assumptions include 800 MHz bandwidth at 28 GHz mmWave carrier frequency, 80 % air resource dedicated for downlink, and full-buffer traffic for all UEs.

Figure 17-(a) shows the simulation result for the gNB-only case, where no IAB-node is provided. 10 out of 18 UEs are in outage (Outage UEs are shown in figure with red circle with back-slash.) due to the blocked radio signals by objects such as buildings, trees, or etc. The sum of DL throughput of the remaining 8 UEs is 1.25 Gbps.

Figure 17-(b) differs from case a), in that, two IAB-nodes are situated along the boulevard toward the north. Each IAB-MT is deployed at a height of 13 meters from the ground. Thanks to the existence of a LOS ray between each IAB-MT and the IAB-donor, a single hop backhaul link to the IAB-Donor is formed for each IAB-node. IAB-DUs are installed facing the west so that most outage UEs are within their boresight angle. As a resource sharing method, TDM is considered to sufficiently allocate radio resources to backhaul and access links in a 50:50 manner. That is, 50% of air resources of the IAB-donor is specifically assigned for backhaul link between the IAB-donor and the two IAB-MTs. Note that each IAB-MT is connected to the IAB-donor via single hop, which means that it is in a star-topology. The UEs served by the IAB-DU1 are marked with blue antenna bars, and the UEs served by the IAB-DU2 are marked with green antenna bars. Most outage UEs in case a) turns to active UEs and are served with strong signal from IAB-DUs. Adding IAB nodes results in not only the coverage expansion, but also throughput increase up to 2.07 Gbps, which is 66 % higher than that of case a). It is worth noting that an IAB can increase the total throughput by making signal quality stronger, even though the IAB-donor uses only half of its air resource for backhaul link purposes.

As mentioned in the previous sections, securing LOS between IAB-donor and IAB-node is a crucial step in reaping the most benefit from IAB deployments. Samsung will further investigate IAB deployment cases in various environments including real world field tests.

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IAB in 3GPP StandardsSamsung has been a key contributor to the development and standardization of IAB since the early days of 3GPP IAB Study Item (SI) preparations. Samsung has helped 3GPP identify main use cases of IAB and develop relevant technology, through its widely recognized leadership in mmWave mobile access. During the SI phase (2018), Samsung acted as co-rapporteur and provided key assistance in producing a high-quality IAB Technical Report (TR) (38.874). Through contributions to numerous sections, Samsung helped ensure a full coverage of topics and a forward-looking, down-scoping process, which ultimately led to the successful approval of the TR at the December 2018 RAN plenary of the Work Item Description (WID) and shaped the Work Item (WI) phase (2019).

Samsung's expertise in network design has resulted in a large number of high-quality 3GPP contributions to all major IAB topics, including the use of Dual Connectivity in IAB networks, bearer mapping and routing, BAP design, node integration, resource multiplexing between access and backhaul links, and IAB-specific changes to RACH.

Possible Scope in 3GPP Release 17Discussions of IAB work for Rel-17 have just begun. Below are some of the items that Samsung thinks are crucial for Rel-17 work on IAB:

•　SDM enhancement •　Full duplex (as explained in the IAB Technology chapter)•　Multi-hop backhauling enhancements•　Support of mobile IAB-node: Moving relay nodes acting as urban cell sites (e.g. taxis, buses, subway) and

country-wide moving relay nodes (e.g. train/high-speed train)

Figure 18. IAB timeline in 3GPP RAN

RAN1Stage-3

Rel-16 IAB Study Item

20212018 2019 2020

Stage-3 completion,ASN. 1

Rel-17 IAB Work Item

Rel-16 IAB Work Item

Abbreviations3GPPAMAMFARQAUBAPBHCAPEXDLDUE-UTRAFDMgNBGWIABIPLOSMACMMEmmWaveMTNE

3rd Generation Partnership ProjectAcknowledge ModeAccess and Mobility Management FunctionAutomatic Repeat RequestAccess Unit Backhaul Adaptation ProtocolBackhaulCapital ExpenditureDownlinkDistributed UnitEvolved Universal Terrestrial AccessFrequency Division Multiplexingnext Generation Node BGatewayIntegrated Access and BackhaulInternet ProtocolLine of SightMedium Access ControlMobility Management Entity Millimeter waveMobile TerminationNetwork Entity

NLOSNRNSAOPEXPDCPPDUPHYQoSRACHRFRLCRORRCSASDMSSBSTRTDMTEIDUEULUPF

Non Line of SightNew RadioNon-Stand-AloneOperating ExpenditurePacket Data Convergence ProtocolProtocol Data UnitPhysical LayerQuality of ServiceRandom Access ChannelRadio FrequencyRadio Link ControlRACH OccasionsRadio Resource ControlStand-AloneSpace Division MultiplexingSynchronization Signal BlockSimultaneous Transmission and ReceptionTime Division MultiplexingTunnel IdentifierUser EquipmentUplinkUser Plane Function

SummaryIAB is a promising new technology that has been introduced in 3GPP Release 16 standards, which will facilitate and expedite the deployment of new 5G cells. IAB provides a framework where the existing 5G access technology of mmWave spectrum can be utilized for both the access and backhaul. This is an alternative solution to fiber optics, which can be very costly and limited in application. IAB will not only reduce the operator’s cost, but also bring 5G coverage to areas where it would be difficult to install wired backhaul.

Since the IAB technology allows multiple IAB nodes to be cascaded, it is possible to extend the coverage area and increase throughput as opposed to cases where only a single cell is deployed. The utilization of mmWave spectrum, combined with beam sweeping technology, makes the IAB deployment a more superior solution than the RF repeater in extending the coverage range. Samsung’s IAB is a smart and effective solution, ready for outdoor deployments, bringing 5G services where wired cabling is a rare commodity.

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