The Fourth Utility: Designing Buildings for Optimal In-Building Wireless Coverage

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Consumers expect their wireless devices to work wherever they are, which means indoor wireless networks are increasingly important to ensure connectivity both outdoors and inside homes and offices as well as shopping malls, arenas and other public places.

Mobile data traffic on cellular networks is skyrocketing and data usage is expected to continue to increase for the foreseeable future. Service providers are looking for ways to relieve congestion from data traffic by moving some of it onto local, in-building networks while maintaining the quality customers expect from the overarching cellular network. Today, customers experience this while connecting to Wi-Fi hotspots when they enter a business or other establishment. In some cases, wireless operators have installed Distributed Antenna Systems (DAS) or small cells to move traffic off the macrocellular network and onto their DAS or small-cell networks.

Building owners also have a vested interest in ensuring quality indoor wireless coverage for their tenants and those who visit their buildings. Reliable indoor coverage can help attract residential and business tenants to a facility at more attractive rents, provide a platform for building owners to automate operational processes, and ensure public-safety communications requirements are met.

While indoor connectivity is taking the shape of a new essential utility for most buildings, it isn’t always considered during initial architectural drawings, or early on in the process for designing new buildings. In fact, some other building designs, like low-emission glass and building material choices like aluminum, hinder RF transmission, necessitating the need for in-building connectivity to be brought into the venue. Further, established buildings also may suffer from poor in-building connectivity, resulting in them being less desirable when trying to rent to tenants or enabling employees’ productivity.

Much of the cost of deploying in-building cellular coverage can be defrayed by including plans for cellular connectivity into the process early on in the design stage for new buildings or during planned renovations to an existing building. It is easier to run necessary fiber, antennas and other equipment when ceilings, floors and walls are exposed. In existing buildings, adding wireless infrastructure should be included during remodeling efforts or as stand-alone service. Designers who think ahead about the venue’s cellular and public-safety connectivity needs can plan ahead accordingly to make the process less costly.

Many factors influence how in-building networks are designed and optimized within buildings, including availability of fiber, cabling pathways, physical space to house equipment, building aesthetics, carrier approvals, power requirements, ongoing maintenance needs, size of the building and traffic patterns within the structure. While each venue is unique, they generally have common design, approval and construction issues. Upfront preparation, thoughtful design and continued project support can save significant installation time, improve design efficiency and reduce costs even in the most difficult project environments.

The following list of considerations excerpted from WIA’s white paper “Planning for Mobile Broadband Connectivity at the Architectural Design Phase” should be part of the initial design process and followed during construction of the system.

  • Depending on size of the building(s)/venue and the number of wireless carriers connecting to the DAS, having a common equipment space for the head-end equipment is critical and often difficult to find. When an available space is reviewed, it should consider a number of design aspects. Locating equipment in existing IT rooms and closets can be an option. However, the building IT department will need to review and understand future space and resource requirements for both the building IT and DAS equipment. Often these spaces end up on mechanical, basement or parking levels, which can pose a number of environmental issues. The design in these areas should be reviewed carefully to mitigate issues like moisture and dust.
  • HVAC is critical for DAS equipment spaces. Existing cooling capacity should be assessed for both the initial and anticipated future growth of the system. Dedicated IT cooling is required year round so standard building cooling or small residential type applications should be reviewed carefully for this application. HVAC systems that are designed specifically for IT applications and that are scalable are strongly recommended. Duct work and raised floor applications required for proper air circulation should be coordinated with the cabling design to minimize pathway conflicts.
  • Power for the DAS head-end is an important consideration. Capacity of the existing power distribution system should be analyzed. Neutral-host DAS power designs should include considerations for the additional requirements of future carriers. If the building is supplying the power, metering and interconnection for smart-building monitoring will need to be coordinated with building management. Utility metering will require coordination with the local power provider and can be a long lead item that can delay system activation. Utilizing building back-up power or installing a back-up generator to harden the system are also design considerations.
  • Fire protection for the head-end and maintenance of existing fire wall assemblies is another important design consideration. For spaces with existing sprinkler systems, new walls or rooms within the space may require modifications for additional sprinkler heads. For critical system infrastructure or larger DAS systems, a pre-action sprinkler system may be a consideration to reduce the chance of accidental discharge. Clean agent gas systems like the FM-200 fire suppressant agent also can be used to minimize damage to the electrical equipment should fire suppression be required. Early warning notification air sampling systems also can be employed to minimize notification and response time to a smoke or fire situation. Fire stopping of cabling and utility penetrations throughout the building is also an important consideration. All wall/floor penetrations should be sealed to maintain the existing wall rating. This is especially critical in hospital environments, where wall fire ratings are critical to the venue’s evacuation plan. For penetrations where future cabling is anticipated, penetration products are available that are re-sealable and speed up future cabling installations. It should be noted that cabling should never be routed through egress hallways or stairwells unless it is related to the function of that egress as allowed by the building code. Cabling that passes through plenum spaces is required to be plenum rated to meet low-smoke, low-flame spread requirements.
  • The design requirements for accessory equipment cabinets should not be overlooked. Depending on the system manufacturer and system configuration, remote cabinets that are required for conversion from fiber to coaxial cabling will need to be located throughout the building. Locations for these remotes are often in IT or mechanical rooms, where space may be limited, so performing initial walks of potential remote locations should be performed during the design phase. Considerations for power and back-up batteries should be reviewed and included as part of the design. Once a design is completed, the construction activities and sequence should be reviewed with the building owner, system designer, architect/engineer and system installer. Work hours, restricted access points, tenant space restrictions, union requirements, preferred specialty vendors, etc., are all critical points for discussion. Coring and fire stopping of vertical and horizontal pathways for RF cabling and power are critical. Scanning of floor and wall penetrations often will be required and review of pathways is key to identifying areas that require cutting and patching because they do not have accessible ceilings. Working in an unoccupied space can eliminate many of these issues, but often installations must be done in occupied tenant spaces. Antenna locations and aesthetics should be reviewed and approved by the building owner and tenants. Providing a mock-up and standard mounting details can reduce antenna/cabling relocation after construction begins. Detailed color-coded floor plans with equipment locations, vertical and horizontal riser locations and antenna locations can be a useful tool to display the entire system design and can significantly reduce change orders from installers that can arise from undefined system requirements and unclear scopes of work.

“Planning for Mobile Broadband Connectivity at the Architectural Design Phase” was written by WIA’s Innovation & Technology Council. Visit WIA’s Resource Library for more informative white papers on topics ranging from Rural Broadband to 5G.

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