Warehouse

Warehouse environments present unique challenges in Wi-Fi design, due to factors like high ceilings, metal shelving, dynamic inventory levels, and environmental conditions. This guide offers a comprehensive approach to designing robust and reliable Wi-Fi networks tailored to warehouse environments.

Challenges

• Large spaces: Warehouses often have vast, open areas that require extensive coverage. Each AP typically covers a larger area, ranging from 3,000 to 8,000 square feet (900 to 2500 square meters), compared to smaller indoor environments.

• Tall structures and obstacles: The height of warehouse ceilings and storage racks, combined with heavy shelving and large equipment, adds complexity to coverage planning. These factors create physical obstructions that can interfere with signal propagation.

• Variable Climate Control: Temperature-controlled areas such as refrigerated or freezer zones create challenging RF conditions. Extreme cold, insulated walls, and sealed doors can alter signal propagation, cause condensation on equipment.

• AP mounting and cable management: Due to the unique warehouse layout, finding suitable mounting locations for APs can be difficult. Additionally, planning for power and data cable runs needs to account for both vertical space and potential obstacles.

• Inadequate indoor APs: Standard indoor APs often struggle to cover the long distances and large spaces typical of warehouses. This necessitates the use of more powerful, specialized APs.

• While APs utilizing external antennas, also known as connectorized APs, may offer more flexibility, they add both hardware and labor costs. They also introduce the potential for greater risk during installation and future maintenance.

Key design considerations

• Warehouse size: The overall square footage will dictate the number of APs needed for adequate coverage.

• Ceiling height: Taller ceilings require higher-powered APs or more APs to ensure signals reach the ground.

• Rack height: The space between the AP and the top of rack impacts how the signal propagates.

• Client density: The number of devices that will be connected to the network at any given time impacts both throughput requirements and the number of APs needed to handle traffic. In warehouses, device density is typically much lower than in an office space, but coverage still needs to support scanners, handhelds, and IoT devices reliably.

• Location or wayfinding: If the design includes location-based services (e.g., asset tracking or employee navigation), this must be factored into the network’s design to ensure accuracy and reliability.

• Types of goods stored: Different materials and objects stored on shelves can influence signal strength due to varying levels of radio interference.

• Hostile Environmental Conditions: Unlike office buildings, many warehouses are partially exposed to the elements and lack consistent heating or cooling across the entire space. This subjects networking equipment to greater temperature fluctuations and harsher conditions. An example of an additional challenge that is not uncommon is the presence of bird or rodent nests in rafters or eaves.

• Layout and content changes: Warehouses are dynamic environments where layout and inventory can change frequently. The Wi-Fi design should be adaptable to these changes, ensuring reliable coverage even as the space evolves.

• Outdoor areas: If the design extends beyond the warehouse building (e.g., docks, yard spaces), outdoor APs or mesh networks may be necessary.

• Client types: Different types of devices, such as scanners, tablets, forklifts, and mobile phones, may have varying power requirements and need to be considered when designing the network.

These factors should be considered to create a robust and scalable Wi-Fi design that accommodates the unique challenges of warehouse environments.

AP placement strategies

There are two main options for HPE Aruba Networking Access Points placement: ceiling mounting and wall mounting. Each method has pros and cons, and in some cases, one may not even be feasible depending on the environment.

Ceiling mount

Ceiling placement is often the ideal choice for warehouse environments, offering several advantages:

• Better Coverage: Ensures more uniform coverage along the floor, reducing RF propagation, especially in the 2.4 GHz range.
• Less Interference: Minimizes signal obstruction from moving equipment or products.
• Staggered Placement Flexibility: Works well with staggered AP placement, where adjacent aisles benefit from coverage despite no AP being directly overhead.
• Ideal for Large Spaces: Ceiling mounts are more adaptable for large warehouses, providing broader coverage and easier access for maintenance.

To understand the color-to-coverage mapping, refer to Visualization settings and heatmap.

Wall mount

While wall mounting is often a secondary option, this method can still be effective in certain situations, such as when ceiling placement isn’t possible. However, wall mounting comes with some limitations:

• Focused Coverage: Typically targets coverage down a single aisle, but may struggle to provide consistent coverage across the warehouse.

• Potential Interference: Walls can block RF signals, and moving equipment (like pallets) might cause signal shadowing, roaming issues or RF pollution across aisles.

• Use Case: Best suited when ceiling mounting isn’t an option, or when aisle-specific coverage is needed.

Staggered placement

Whether using ceiling or wall mounts, staggering APs (placing APs in alternating aisles) helps improve coverage. For ceiling-mounted APs, staggered placement ensures that every other aisle gets signal from adjacent APs. In wall-mounted setups, APs on opposite walls cover alternating aisles for the same effect.

Signal Spread: 3 AP case study

When comparing the signal propagation of wall-mounted versus ceiling-mounted 3 APs, note that the wall-mounted AP shows significantly more signal bleed along the walls compared to the ceiling-mounted AP.

AP height and rack spacing considerations

AP height: AP height is a critical aspect when APs are ceiling mounted. The first consideration regarding AP height is that as mounting height increases, path loss also increases. This effect depends on both the AP model and the antenna pattern. With omnidirectional antennas, for example, the signal-to-noise ratio (SNR) typically decreases directly beneath the AP as height increases.

Example: AP is positioned closer to the floor, resulting in a stronger signal directly beneath the AP.

Rack spacing: The space between the AP and the top of the rack plays a crucial role in determining the path loss geometry through the rack. Generally, increasing this gap allows the RF signal to better propagate into adjacent aisles. However, if the height becomes too great, directional antennas may be necessary to maintain optimal coverage.

AP is mounted higher, leading to a lower SNR at ground level.

This reduction in signal strength can lead to coverage gaps and roaming issues for client devices.

The heatmap clearly shows a noticeable drop in overall SNR. This decrease is primarily due to the omnidirectional APs focusing their RF signal more horizontally, rather than directing the signal downward toward the client devices.

Directional vs omnidirectional APs

For ceilings over 15 meters, using APs with directional antennas helps direct most of the RF energy downward, improving SNR for clients. This setup ensures that clients maintain a strong connection and are less likely to reach their roam thresholds prematurely, only triggering roaming when necessary.

RF path loss and attenuation

In warehouse environments, RF path loss and attenuation are significantly influenced by shelving and racking structures. Metal racks and densely packed inventory can cause substantial signal degradation, with attenuation levels varying based on materials and stocking density.

Shelving impact

The biggest challenge in warehouse RF planning is the shelving, as shelving acts as a significant barrier to RF propagation. Shelving units can attenuate signals to varying degrees from one aisle to the next, creating coverage gaps.

When planning AP placement, consider the height of the racks in relation to the ceiling and the AP position. This is crucial for understanding how RF will propagate over and between the shelves into the aisles.

RF signals from an AP positioned directly above an aisle will cover that aisle effectively. However, adjacent aisles will experience attenuation as the signal travels through the racks and materials. The more material stored and the larger the rack configuration, the greater the RF loss.

The level of attenuation is determined by the materials stored and the specific layout of the racks. Additionally, increasing the spacing between APs across aisles can lead to RF gaps, reducing coverage in the areas between the racks.

Impact of rack RF attenuation

When designing with the assumption that enough RF can pass through each shelf, and opting to skip every other aisle, the 3-dimensional nature of path loss through the shelving can result in significant coverage gaps. Additionally, this design lacks redundancy, meaning there’s no backup coverage if an AP fails.

Example 1:

Some aisles have good coverage, while others experience poor but still sufficient coverage.

When shelves store materials that severely attenuate RF, coverage across more aisles becomes weaker.

When an AP fails, there’s no fallback coverage, leaving large gaps where signal strength is insufficient.

AP selection

Using outdoor APs

Warehouse environments often lack full environmental control, with extreme temperatures near the ceiling, potential leaks, precipitation, and the presence of animal and insect deposits. These conditions can be tough on standard APs, making outdoor-rated models a better option for many warehouse setups.

Outdoor APs are designed to withstand harsh conditions, with weatherproofing that allows the outdoor APs to survive wider temperature extremes—even in environments like refrigerators and freezers. Outdoor APs also feature more suitable antenna solutions and higher radio power levels, making the APs ideal for covering larger areas at the taller heights typically found in warehouses.

In addition, outdoor APs and their mounting solutions are built to be more rugged and can be staged, provisioned, and installed quickly and securely. Unlike indoor APs, outdoor APs don’t require costly enclosures or external antennas, which saves on both hardware and installation time. This results in less risk, easier long-term maintenance, and lower total cost of ownership.

Using indoor or connectorized APs

While using indoor APs may be necessary as a cost-saving measure, recognizing the limitations they impose is important. Indoor APs generally have lower transmit power, which can restrict coverage and effectiveness in larger or more complex environments like warehouses.

Indoor APs should be considered only when coverage requirements are met and the warehouse has consistent temperature conditions.

APs that utilize external antennas aka connectorized APs, which allow for the use of external antennas, can help mitigate some of the coverage issues by better shaping the RF signal. However, this approach comes with additional challenges. The extra hardware costs for the external antennas, the labor required to install and configure the antennas, and the risk of cabling issues can make connectorized indoor APs not only more expensive but also less effective overall.

Link budget and power management

Older guidelines often suggested that the link budget between an AP and client should be balanced by setting the AP power level close to that of the client. However, with modern MIMO (Multiple Input Multiple Output) APs, as well as technologies like TxBF (Transmit Beamforming) and MRC (Maximal Ratio Combining), this approach is no longer as critical.

Even when the AP operates at or near maximum transmit power, the link budget remains sufficient to maintain a reliable connection with the client. These advanced technologies allow for more efficient use of the available RF power, ensuring that signal quality is preserved across the link.

As a result, there is often no need to significantly reduce AP power in most cases. In fact, maintaining higher AP power can help ensure better coverage, especially in larger or more complex environments, without negatively affecting the overall link budget.

Design & deployment process

The warehouse deployment process can be broken down into three distinct phases. To ensure a consistent and successful deployment follow the process:

Phase 1: Predictive site survey

The first phase involves gathering data to create a predictive model for the wireless network design.

• Obtain scaled drawings: Acquire scaled drawings (preferably PDFs) of areas to be covered, including racking layout, walls, ceiling height, and rack height/depth in each area.
• Review existing wireless Deployment: Obtain layout of current wireless deployment: AP models, antenna types, placement, installation heights, Intermediate Distribution Frame (IDF), current configuration (power, channel plans, bands).
• Gather Information on Planned Client Devices: Collect details on client devices and use cases (e.g., handheld scanners, VoWiFi phones, laptops), including device type, band capability, model, and firmware level.
• Teleconference with Stakeholders: Review gathered information, address coverage issues or functional concerns with the current deployment, discuss warehouse use (e.g., types of goods stored) and seasonal operational variations.
• Create a model of existing coverage:
  • Use a modeling tool like Ekahau, hamina, etc to create a model of existing coverage based on current AP models and antenna types.
• General criteria summary:
  • Primary AP Coverage: -65 dBm (or -60 dBm for voice).
  • Secondary AP Coverage: -72 dBm (failover).
  • Assume closed doors and solid walls based on construction type.
• Attenuation areas for racking:
  • Dry goods/unknown: 3 dB/m.
  • Liquids: 10 dB/m.
• Create a model of proposed coverage: Place APs based on existing locations, adjust positions or add new ones to meet best practices for coverage.
• Stakeholder review: Hold another meeting to review the existing and proposed predictive models, address areas to evaluate in Phase 2 (Physical Site Survey).

Phase 2: Physical site survey

This phase validates Phase 1 information and allows for adjustments based on real-world conditions.

• Site walkthrough:
  • Walk the warehouse to verify data from Phase 1, using laser tools to confirm dimensions.
  • Verify racking layout, aisle lengths, widths, racking heights, depths, ceiling height, AP installation heights.
  • Confirm compatibility of proposed AP locations with warehouse layout and confirm IDF locations.
  • Ensure all existing APs are active and functioning.
• Photographic documentation:
  • Take photos of representative AP installation types and proposed locations.
• Passive survey:
  • Use a modeling tool to conduct a passive survey of existing coverage by walking all aisles and collecting data.
• AP on a stick survey:
  • Mount an Aruba AP as representative of future installation and perform a passive survey using a test SSID.
  • Purpose: gather data to demonstrate improvements in coverage compared to the existing design.

Phase 3: Design of record

This final phase compiles all data into a comprehensive plan for installation.

• Document the design:
  • Title the document and include site information (name, address, contact details).
• Review of existing deployment:
  • Include a layout of each floor showing AP locations and IDFs (no heatmap required).
  • Provide predictive coverage of the existing layout at -65 dBm (primary coverage) and -72 dBm (secondary coverage).
  • If applicable, include measured survey data from site walk.
• Review site walk data:
  • Include additional data gathered during the physical survey and review discrepancies or changes.
• Review of proposed deployment:
  • Provide layout of each floor with proposed AP locations and IDFs (no heatmap required).
  • Show predictive coverage at -65 dBm (primary coverage) and -72 dBm (secondary coverage).
  • Review measurements taken during the physical survey with proposed APs.
• Final summary:
  • Summarize the design, highlighting key decisions and elements from the process.

By following this structured approach across all three phases, the wireless network deployment is thoroughly planned, validated, and documented, ensuring a successful installation in the warehouse environment.

Visualization settings and heatmap

The thresholds of the signal can be selected in coverage visualization tools like Ekahau or Hamina. These colors on the floor plan represent adequate coverage for a client. Below are the settings used to create the images in this document.

Red: -64 dB coverage threshold

Green: -53 dB

Grey: -67 dB to -70 dB

The EIRP set for 5 GHz band radio is set to 200 mW.

Best Practices

• AP selection and mounting

  • Use outdoor omnidirectional APs and directional APs with industrial AP mounts for easy installation, enhanced security, and simplified setup.
  • Ceiling height considerations
    • Use outdoor omnidirectional for warehouses with ceiling heights of 45-50 feet and under.
    • Use outdoor directional APs for warehouses with ceiling heights above 50 feet.

• AP placement and coverage

  • Place at least one AP per aisle. Depending on aisle length, more than one AP may be required.
  • Ensure APs are spaced according to design guidelines.
  • Maximize separation
    • Position APs to maximize the distance from the top of warehouse racks to optimize signal and reduce interference.
  • Ceiling-based coverage
    • Create cellularized coverage from the ceilings for optimal RF performance.
    • Minimize wall mounting of APs unless necessary to avoid unwanted RF propagation throughout the warehouse.

• Design guidelines for AP spacing

  • For outdoor omnidirectional APs:
    • Maintain a spacing of 50-65 meters between APs along the same aisle or perimeter.
  • For outdoor directional APs:
    • For ceiling heights of up to 13-14 meters (45-50 feet), maintain spacing of 40-50 meters between APs.
    • For ceiling heights above 14 meters (50 feet), increase spacing to 50-65 meters between APs.

These guidelines ensure optimal coverage, performance, and scalability for warehouse networks.

AP selection recommendation

When designing a wireless network for a warehouse, approaching AP placement with the unique requirements of different areas in mind is essential, as each zone may have specific AP types and coverage objectives. Below is a general approach to AP placement:

• High racking zones

  • AP model selection: Use outdoor omnidirectional APs for racking heights up to 13-14 meters (45-50 feet). Use outdoor directional APs for racking heights greater than 14 meters (50 feet).
  • Placement strategy: Place APs in a staggered pattern and close to the ceiling, ideally positioned in every aisle or every other aisle, depending on the types of goods stored and the required coverage. Adjust spacing as needed, ensuring proper coverage for the different rack heights and aisle lengths.

• Perimeter and load/unload areas AP placement: Install an AP approximately every 150 feet along the perimeter, focusing on areas with load in/load out activity, where movement is frequent. Strategically place APs on aisles that are empty or position the APs at the far end of busy aisles to optimize coverage and minimize interference.

• Open areas

  • AP model selection: Use outdoor omnidirectional APs for ceiling heights up to 13-14 meters (45-50 feet). Use outdoor directional APs for ceiling heights greater than 14 meters (50 feet).
  • Placement strategy: Install APs on a grid pattern, with spacing of approximately 50-65 meters (150-200 feet). This ensures broad coverage and reduces the risk of coverage gaps in larger, open spaces.

• Outdoor AP placement

  • AP model selection: Use outdoor directional APs for outdoor areas.
  • Placement strategy: Wall-mount the APs, ensuring APs are oriented outward, away from the building to cover the surrounding perimeter. Space APs along the outer walls, placing the APs approximately every 50 meters (150 feet) in a linear arrangement to ensure consistent outdoor coverage.

• Office area AP placement AP model selection: Typically, use indoor omnidirectional APs for office areas, depending on the required coverage and density.

By organizing the AP placement strategy by zone type and considering the specific needs of each area, this approach ensures comprehensive and efficient coverage throughout the warehouse. Always adjust placement based on site specifics, including racking height, aisle width, and warehouse layout.