Wireless Lessons from Construction Sites

Summary

Construction sites, especially industrial or commercial construction, can be highly dynamic environments characterized by heavy machinery, tools and people in constant motion. Activities within the construction environment must be coordinated and monitored to efficiently achieve daily goals, monitor the health of equipment, monitor the ambient environment and assure the safety of the people working within the construction environment. As with the industrial plants that will ultimately be built, reliable and rapid wireless communication is a key requirement for construction sites and the 5G network is a lead contender in supporting its mix of applications. Exploring private 5G service classes enriches our understanding of tailoring next-generation wireless communications networks to industry needs.

At the Communications Technology Laboratory of the National Institute of Standards and Technology (NIST) in Gaithersburg, MD, USA, we’ve been addressing the challenges of integrating 5G networks and exploring ways to test and predict wireless network performance in dynamic environments. This is an excerpt of our recently published whitepaper in which we explore deploying wireless communication networks within construction projects, introduce a comparison approach to assessing deployment difficulty at each project phase, and discuss our plans for a testbed for 5G communications that can help shape the future of wireless communications.
 

Physical environment considerations

During our investigation, we discovered that the key elements affecting the viability of a construction network and simplified them to three principal considerations relating to the physical environment:

• the geometry of the work zone,
• the number and materials of the walls being constructed, and
• the types of materials used to construct floors and ceilings.

Much research has been undertaken to characterize the propagation characteristics of construction spaces primarily focusing on the finished industrial spaces. While it is important to understand all of the impacting factors of a work zone, we must be careful to capture the factors such that they minimally overlap in their impacts on wireless system performance. This approach is synonymous with maintaining the linear independence of variables in a system of linear equations, and we attempt to maintain this independence throughout this work.

We should also note that the focus so far has been on the physical environment, yet construction has other factors that can otherwise degrade the performance of the construction network such as radio frequency interference from welding, unshielded power electronics, and co-existing network traffic. Additionally, the impact attributes for each scenario were assigned a value for three stages of construction: Early-Stage, Mid-Stage and Late-Stage.
 

5G service categories

Exploring 5G service classes for construction enriches our understanding of tailoring next-generation wireless communications networks to industry needs. Why consider 5G at all? Its versatile wireless technology accommodates diverse communication needs and deployment structures, making it suitable for various construction applications. While other wireless solutions are viable, we opt for 5G stand-alone (SA) private networks for several reasons:

• Firstly, 5G’s built-in determinism, leveraging time and frequency diversity supports channel resource allocation. Spatial diversity is enhanced with multiple-input multiple-output (MIMO) antennas, including massive MIMO systems for optimal device support and beam directionality, ensuring a higher quality of service. 
• Secondly, 5G offers quality of service (QoS) support and flexibility in enforcing reliability policies through different service classes and network slicing.
• Additionally, it supports licensed and unlicensed deployment options, expanding available RF bands and is progressing towards supporting various industrial protocols for improved interoperability in automation systems.

There are three main 5G service categories: enhanced mobile broadband (eMBB), massive machine type communication (mMTC) and ultra-reliable low-latency communication (URLLC). A new service class, reduced capability (RedCap) is emerging that offers reduced capabilities compared to that of URLLC class with less stringent latency and reliability requirements. This makes it more cost-effective and energy efficient.
URLLC, with 1 ms latency and reliability exceeding 99.999%, is particularly relevant for construction applications. However, considering cost and battery life, RedCap may become a preferred choice for some applications.  URLLC achieves low latency by allowing transmissions to interrupt lower-priority ones through the mini-slot concept and periodic grant-free transmission. URLLC can support connectivity for automated guided vehicles, mobile robots, teleoperated heavy machinery and safety equipment in various construction scenarios.

The eMBB category, with peak data rates up to 10 Gbit/s, benefits high-data-rate applications like augmented reality and remote operation video feedback. The mMTC category, with a node density of up to 100 nodes/m2, is suitable for massive wireless sensor networks, site 11 asset management and various monitoring applications.

A 5G network is not confined to a specific service category, as these categories represent network performance limits from different perspectives. Generally, a 5G implementation can meet specific communication demands through QoS guarantees enforced by the user plane function (UPF) in the 5G core network.

5G enabling capabilities

Various 5G releases offer capabilities to meet diverse service category demands, including those vital for construction communication networks. Key features such as network slicing, QoS support, software-defined networking (SDN) and network function virtualization (NFV) enable dynamic resource allocation and separation of user and control plane functions. Network slices, tailored to specific QoS requirements, span core network to radio access network (RAN) domains, while multi-access edge computing (MEC) places computing resources closer to the RAN and within construction sites for low-latency applications.

Specific capabilities introduced for industrial wireless support in 5G include 5G-time-sensitive networking (TSN) integration and Open Platform Communications Unified Architecture (OPC UA) support. In release 18, 5G-TSN integration achieved centralized TSN implementation, ensuring time synchronization and timely data delivery through traffic shaping and scheduling. The generic precision time protocol (gPTP) facilitates time synchronization between nodes.

Additionally, OPC UA (IEC 62541-1) standardizes data communications in industrial automation, enabling vendor-neutral interoperability. Integrating 5G with OPC UA allows construction applications to operate over 5G, facilitating coexistence and communication with legacy systems. Interaction with OPC UA devices can occur through TSN middleware or directly via the network exposure function (NEF) introduced in release-16.

 
5G uses cases in construction

Many 5G use cases in the construction industry are being considered at other industrial sites and each makes use of specific 5G service categories described in our paper. As shown at the top of Figure 1, streaming video would utilize the eMBB service category. Streaming video enables situational awareness of construction activities as well as security monitoring of the work zone. Additionally, streaming video has become an essential part of the teleoperation of machinery and drone-based inspection. Streaming video is, therefore, an essential component of most, if not all, construction projects.

Streaming high-definition (HD) video at a rate of 60 frames per second equates to a minimum of 5 Mbps with a peak bit rate of 10 Mbps. The high video quality may seem excessive, but it’s likely necessary for teleoperating heavy machinery around people in the work zone and for drone-based inspections. Furthermore, several of these activities operating concurrently would have a multiplying effect on the 5G system.
 
[optional pullquote] Streaming video enables situational awareness of construction activities, security monitoring, the teleoperation of machinery and drone-based inspection. Several of these activities operating concurrently would have a multiplying effect on the 5G system.

5G testbed for construction

To enhance our understanding and practical application of expertise in 5G construction environments, we conducted a literature review for applicable testbeds and channel measurements. Despite finding various experiments on 5G propagation in indoor and outdoor settings, we did not identify a suitable 5G testbed specifically designed for construction environments.

The literature highlighted limitations in current wireless communication capabilities in construction, and discussed the need for 5G applications in construction. Given the lack of comprehensive coverage for construction scenarios, we recommend and plan to develop a dedicated 5G testbed for researching construction-specific concerns.

Unlike conducting wireless network tests directly in an actual construction environment, our testbed would offer enhanced flexibility for system validation and testing. It allows emulation of real-world environments without affecting operational settings, easily adapts to diverse use cases and provides more accurate results than simulations.

The testbed includes 5G system hardware, various 5G-compatible user equipment (UEs) from different vendors, PCs, industrial collaborative robotic manipulators and networking devices. Our current focus is establishing a remote operation control scenario with different IIoT traffic and interference, a common use case in construction.

More about the design of the testbed can be found in our whitepaper.
 

Looking ahead

The advancement of wireless communications in the construction industry presents a myriad of exciting research opportunities that can shape the future of infrastructure development. These research opportunities offer a road map for research engineers and industry practitioners to collaborate and contribute to the evolution of wireless communication technologies tailored to the unique demands of construction and industry.
Our whitepaper addresses complex wireless communication challenges in the construction industry and provides a way forward for further research and development. It introduces a systematic scoring system to assess wireless connectivity difficulty throughout construction phases, incorporating a comprehensive set of attributes. We also present a novel testbed design for deploying and exploring strategies in a simulated construction environment.
 
_{This feature originally appeared in the June 2024 issue of InTech digital magazine.}