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Guideline

UCSF Wireless RF Design Guideline

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Overview

As healthcare continues to undergo digital transformation, networking technologies serve an increasingly vital role: Enabling Electronic Healthcare.

  • As UCSF continues to embrace mobile applications and platforms, the wireless network has become one of our most strategic assets supporting our ability to innovate.
  • UCSF RF design standards meet regulatory, compliance and information security requirements while never losing sight of our top priority in all things: the wellness and safety of our patients and staff.

Document objective

This document defines key requirements and standards to which UCSF IT and supporting vendors must adhere when designing, deploying and maintaining wireless technologies.

  • The general intention is to address all key wireless technologies.
    • However, the main focus is on Wi-Fi, given the widespread adoption of Wi-Fi technology.
       
  • Secondarily, this document explains the reasons why the standards are defined as they are.

Audience

This document is intended for all vendors and USCF IT personnel involved in wireless systems design, deployment and operations.

Topics

  • Wireless spectrum policies and standards
  • Design and deployment requirements for wireless technology systems
  • Definition of minimum and target acceptance criteria for different wireless technologies
  • Documentation on methods and practices that must be completed for all deployments

Wireless spectrum policies and standards

Wireless spectrum is a finite asset that must be coordinated between UCSF stakeholders. Most wireless systems do not share wireless spectrum without negative effects. Before UCSF deploys wireless technologies, spectrum coordination needs to be facilitated by all stakeholders involved with UCSF facilities.

UCSF spectrum allocation. Note that newer nomenclature for reference to the U-NII 2e band is sometimes used. (U-NII 2 is also known as U-NII 2a, and U-NII 2e is also known as U-NII 2c.) U-NII 2b spectrum is not available for Wi-Fi use at this time.

2.4 GHz ISM band

Wi-Fi for RF channels 1 (2412 MHz), 6 (2437 MHz) and 11 (2462 MHz)

  • Wi-Fi uses 20 MHz-wide channels for OFDM transmissions.
  • Legacy DSSS mode for 802.11b and earlier is not recommended at UCSF.

Bluetooth Classic

  • Bluetooth Classic uses a frequency- hopping pattern across the entire 2.4 GHz band, so its use is discouraged.
  • Bluetooth Classic device deployments should be submitted to UCSF IT to quantify interference impact and business case.

Bluetooth Low Energy (BLE)

  • BLE is a very different form of Bluetooth that only uses the spaces between Wi-Fi channels 1, 6 and 11 and is recommended by UCSF IT.

Microwave ovens

  • Microwave ovens use 2.4 GHz to cook food.
  • Only commercial microwave ovens are recommended at UCSF, as consumer units tend to have poor shielding.
  • Over time, all microwave ovens may lose their shielding capacity and therefore create substantial interference in 2.4 GHz—usually in the middle and higher part of the band.

3.5 GHz CBRS

LTE systems

  • The FCC recently ratified the use of 3.5 GHz, which can be licensed at a low cost.
  • This band is largely set aside for LTE systems.
  • UCSF does not plan to use this spectrum for non-LTE systems at this time.

5 GHz U-NII

Wi-Fi

  • This is the target frequency band for Wi-Fi at UCSF.
  • 5 GHz Wi-Fi uses U-NII 1, 2 and 3.
  • Occasional use of the U-NII 2 extended (2e) band may be allowed for special-use cases.

5 GHz ISM

Channel 165 (5825 MHz) – 20 MHz

  • May be used for biomedical devices that require Wi-Fi APs attached to mobile units.
  • A typical use case: mobile CR/DR X-ray systems. UCSF has dedicated this channel to be used for these systems without interfering with the Wi-Fi network.

Design and deployment requirements

UCSF requests coordination around all new wireless addition and system upgrades that require the use of wireless infrastructure..

  • To prevent interference to and from other UCSF wireless systems, equipment vendors and UCSF personnel need to:
    • Document their use of radio spectrum
    • Ensure they are configuring their systems accordingly

Wi-Fi

  • Wi-Fi based on the IEEE 802.11 protocol is currently the largest use of wireless technologies at UCSF.
  • Wi-Fi continues to evolve, and UCSF must adapt to such changes including those in the specification and technology advancements.
  • Our Wi-Fi deployments are focused on the use of 5 GHz as the primary frequency spectrum, with 2.4 GHz as a backup if needed.
    • Due to the poor performance characteristics of 2.4 GHz, we discourage its use as a primary technology.
    • This principle must also guide our configuration standards on both infrastructure and devices.

Minimum requirements

5 GHz

  • Lowest basic rate (mandatory rate) of 12 Mbps
  • Transmit power at intentional radiator (excluding antenna gain) must not exceed 14 dBm.
    • Exceptions should be evaluated and discussed.
  • Automated channel and power changes should not exceed changes of greater than twice daily.
    • Less-frequent intervals are encouraged but should be used only if warranted.
  • Standard deployments should use approved channels: U-NII 1, 2 and 3 (channels 36, 40, 44, 48, 52, 56, 60, 64, 149, 153, 157, 161).
    • Use of U-NII 2 should be restricted if a radar or DFS event occurs.
      • The impact of detection strongly affects reliability as well as users, so each such event must be given high priority for address and resolution.
      • Note that, due to erroneous detection, radar detection may occur without the presence of radar.
  • The U-NII 2 Extended band (channels 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140) should be used only for adding additional coverage for high- density situations.
  • Channel 144 is restricted from use at this time.
    • Not all Wi-Fi clients support these channels, so they should not be included in a standard channel plan.
  • Channel bonding is allowed at 5 GHz but must not exceed 40 MHz.

2.4 GHz

  • Lowest basic rate (mandatory rate) of 12 Mbps
  • Transmit power at intentional radiator (excluding antenna gain) must not exceed 11 dBm.
    • Exceptions should be evaluated and discussed.
  • Automated channel and power changes should not exceed changes of greater than twice daily.
    • Less-frequent intervals are encouraged but should be used only if warranted.
  • Only the use of channels 1, 6 and 11 is allowed.
  • No other channels are allowed as they would be overlapping and therefore interfering.
  • Channel bonding at 2.4 GHz is strictly forbidden.

RF design methodologies for Wi-Fi

  • RF designs should be focused on 5 GHz.
    • Any 2.4 GHz coverage will be allowed and optimized to the best extent possible after installation.
  • AP placements should be determined based on active RF measurements in existing construction facilities.
  • Predictive designs may be used for buildings that are under construction, for cabling drop quantities and placements, but APs should not be installed according to a predictive design.
  • Cell edges should conform to generally understood industry best practices of -65 dBm for cell edges, with an adjacent AP coverage of +8 dBm or better to facilitate roaming.
    • When using -65 dBm as a guide for cell edges, it is important to consider differences in device receive sensitivity.
    • At the time of this writing, the iPhone 8 as deployed for clinical communications at UCSF should be the guide for determining an "offset" value for the tool being used for active or passive RF surveys.
  • Before starting any work, discuss with UCSF IT the matter of which device RF designs should be calibrated to.
  • AP transmit power at the intentional radiator (minus antenna gain) should not exceed 11 dBm transmit power for active RF surveys.
  • AP placements should avoid hallways and areas where oblong coverage patterns exist.
  • Higher density and high available considerations should be made for certain clinical departments such as ICU, OR, ED, large conference rooms, equipment staging areas and targeted triage areas for very-high-census events.

Interference detection

  • Wireless AP devices to be purchased by UCSF shall include a spectrum management capability to detect non-Wi-Fi sources of RF interference. 
    • This will be the primary mechanism used for spectrum management as it offers a 24/7 capability, whereas manual, intermittent spot checks for interference use a separate tool.
  • Sources of RF interference exceeding 20 percent duty cycle with a signal exceeding -87 dBm should be reported immediately to UCSF IT staff for immediate resolution.

Validations of existing coverage

  • When validating RF coverage:
    • Before proceeding, the running/active configuration on the infrastructure must be captured and logged for future reference.
    • Channel and power changes should be restricted during the course of the RF validation.
    • If possible during the validation effort, use a currently configured and installed VoIP device for performing a multichannel capture in the environment.
      • Document frame-level analysis to identify key performance characteristics.
  • Post-validation:
    • If changes occur, record log files and (when needed) an additional capture of active configuration.
    • A rendering of power with a single transmit power level is highly desired post-validation.
      • Variances in transmit power can be misleading with regard to actual coverage.

Bluetooth

  • Use of Classic mode Bluetooth is discouraged in healthcare settings.
  • Classic mode Bluetooth cannot exceed 5 dBm of transmit power.
  • Use of Bluetooth Low Energy (BLE) is allowed.

Other technologies

Contact Godwin Abohwo or Tu Luu for guidance.

Acceptance criteria

Our goal is to maximize reliability and safety in order to provide the best patient care possible.

  • RF systems deployed at UCSF must be validated to operate according to the guidelines that apply to the specific technologies.
  • All new purchases and upgrades to existing systems should be reviewed by UCSF IT to determine if they are compatible with existing systems and any strategic plans that may be underway.
  • Wireless systems that have not been approved may be removed from operation if found to cause interference or risks to patient care or safety.

Documentation

All systems must be documented and available for reference by all UCSF staff.

  • Documentation requirements must minimally include:
    • Manufacturer make and model
    • Key configuration parameters such as:
      • RF frequencies used
      • Power
      • Automated configuration parameters that may alter these settings
      • IP addresses
    • Installation locations, clearly documented on maps
    • Equipment labels and asset tags
    • An accountable owner of the system, to facilitate ongoing collaboration and maintenance activities

Vendor RF Survey Standards for > 20k sqft

Service-1: Provide RF Survey services for Wireless Refresh of existing UCSF and affiliate buildings

  1. Perform Active Survey to determine new locations for ALL APs (existing APs to be moved as well as New AP additions)
  2. Passive Survey/Validation
  3. Any remediation of gaps found during Passive survey should follow Active Survey process for identified issues
  4. Communicate Preliminary findings – To be used by Clinical Mobility to communicate necessary remediation as needed so that APs can be added or moved as needed.
  5. Perform another Passive Survey for Remediated Areas after UCSF and Affiliates remediates based on Preliminary findings
  6. Documentation and Analysis which demonstrates Guaranteed RF coverage* and Voice grade design to meet standard developed by UCSF and Affiliates + Clinical Mobility
  7. Clinical Mobility will be responsible for any additional expenses incurred on their part during the project implementation period as a result of a flawed design delivered to UCSF and Affiliates

Service-2: Provide RF Survey services for Wireless infrastructure implementation at New UCSF and affiliate buildings

  1. Perform Predictive Survey to determine AP locations based on CAD drawings
  2. Ongoing co-ordination with Construction for AP placement due to construction changes
  3. Perform Active Survey to validate accuracy of AP placements originally based on Predictive Survey
  4. Communicate Preliminary findings – To be used by Clinical Mobility to communicate necessary remediation as needed so that APs can be added or moved as needed Passive Survey/Validation
  5. Perform Passive Survey for whole building after UCSF and Affiliates remediates based on Preliminary findings
  6. Any remediation of gaps found during Passive survey should follow Active Survey process for identified issues
  7. Perform Passive Survey for areas remediated by UCSF and affiliates
  8. Documentation and Analysis which demonstrates Guaranteed RF coverage* and Voice grade design to meet standard developed by UCSF and Affiliates + Clinical Mobility
  9. Clinical Mobility will be responsible for any additional expenses incurred on their part during the project implementation period as a result of a flawed design delivered to UCSF and Affiliates

Service-3: Perform Bi-Annual Existing Facility Assessment including Passive Survey with performance simulation

  1. Docs/assessment/remediation suggestions
  2. Any remediation of gaps found during Passive survey should follow Active Survey process for identified issues
  3.  Perform Passive Survey for areas remediated by UCSF and Affiliates

Service-4: Perform Advanced Analysis with client device

  1. Onsite packet captures, analysis, recommendations
  2. Documentation/presentation of findings (assuming full day onsite)

Service-5: Assisting with go-live infrastructure deployments

  1. Controller installation, upgrades, onsite validation, etc.