Planning Guide

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Planning your organization's Wi-Fi infrastructure

To provide a positive experience for BlackBerry Mobile Voice System users who use the Voice over Wi-Fi feature, you must consider and understand the different designs and deployments that can impact Wi-Fi calling. During the planning process, you should collaborate with your organization's Wi-Fi infrastructure vendor to make sure that your organization's Wi-Fi infrastructure is designed and configured to support Voice over Wi-Fi calls.

To make sure that your organization's Wi-Fi infrastructure can support Voice over Wi-Fi calls, you should use BlackBerry devices to perform an in-depth site survey. For more information, visit http://www.blackberry.com/support to read article KB13299. Make sure that you conduct the survey during expected service time in an occupied building or work space because people and furniture can impact wireless coverage. The results of the survey should help you to perform the following tasks:

  • Design and configure a Wi-Fi controller-based architecture
  • Identify the type of authentication and level of encryption that your organization requires
  • Configure a QoS implementation
  • Determine the expected Wi-Fi coverage and capacity boundaries of the access points
  • Determine the capacity of your organization's Wi-Fi infrastructure. Make sure that you account for the expected usage for both BlackBerry MVS users and individuals who use Wi-Fi technology on their laptop computers.
  • Verify non-overlapping channel configurations
  • Identify and mitigate the impact of potential interference sources, including microwaves, cordless phones, and Bluetooth devices.
  • Make sure that you have appropriate access point coverage, including considerations for machinery, elevators, stairwells, wall densities, areas between buildings, and cell coverage patterns and antenna direction and attenuation
  • Create documentation for your organization's users to help them configure their devices to connect to Wi-Fi networks and make Voice over Wi-Fi calls

Best practice: Planning your organization's Wi-Fi infrastructure

The following guidelines are intended to help you design a Wi-Fi infrastructure that permits BlackBerry devices to connect to an access point that has a medium-to-high data rate. When the data rate of the access point is too low or the signal strength of the access point is too weak, the device should roam to an access point with a higher data rate or a stronger signal strength. When designing your organization's Wi-Fi infrastructure, you should consider the following guidelines:

  • Establish a minimum signal strength level of -65 dBm in the planned coverage area.
  • Establish a minimum SNR of 25 dB in the planned coverage area.
  • When roaming in the planned coverage area, make sure that it takes no longer than 50 milliseconds to perform an access point to access point handoff.
  • 802.11b-only access points force 802.11g devices to enter protection mode, which reduces the maximum data throughput of the 802.11g devices. You should consider eliminating the 802.11b-only devices to avoid performance degradation in the 802.11g devices.
  • A single call between two BlackBerry MVS Client instances that are associated with the same access point is considered to be two simultaneous voice over WLAN calls.
  • For best performance, use a controller-based wireless network.
  • Avoid using Bluetooth headsets and 2.4 GHz Wi-Fi interference and consider 5 GHz (802.11a) deployments to eliminate potential interference.
  • To reduce BlackBerry device battery drain, use WMM power save standard Unscheduled Automatic Power Save Delivery (U-APSD)
  • Avoid using VPN while on the organization's WLAN network; instead you should use WLAN authentication and encryption based on enterprise security policies.

Using Wi-Fi enabled BlackBerry devices for making and taking BlackBerry MVS calls from a home office or a hotspot is unpredictable because of the instability of those types of networks and cannot be expected to be as reliable as when the user is in a controlled environment. If your organization's users make Voice over Wi-Fi calls from a home office or hotspot, you must make sure that the integrated VPN client on their BlackBerry devices is configured for a connection to your organization's network through the Internet.

For more information about planning your organization's Wi-Fi infrastructure, visit http://us.blackberry.com/ataglance/networks/deploying_wireless_lan.pdf to see the Considerations for Planning and Deploying a Wireless LAN document.

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Planning a voice grade WLAN

To avoid overestimating the cost of the WLAN or underestimating the coverage and capacity that you need, you must have a good understanding of your organization's WLAN requirements.

Key application parameters to consider when planning a WLAN deployment include:

  • Application mix
  • Relative proportion of voice and data traffic
  • Expected traffic demands
  • Application performance requirements

There are many areas within a WLAN design that can affect the voice quality on a WLAN. The WLAN architecture, roaming, QoS, and RF planning all place demands on the connection quality, coverage, and user experience when using VoWLAN. Voice applications are sensitive to latency or delay, jitter, and packet loss. The delay requirements for conversational voice are more strict than for any other application. For optimal conversational voice quality, the end-to-end one-way delay should be less than 150 milliseconds.

A number of factors can contribute to the one-way delay, so the WLAN can only use a small portion of the total 150 millisecond delay. Significant contributors to the delay include the packetization, propagation, de-jitter, and playout delays. Other delay contributors include processing delays in the end systems and queuing delays in the network routers and switches. In a typical organizational network, the WLAN network should use approximately 50 milliseconds of the total 150 millisecond end-to-end delay. The communications delay between a WLAN phone and the AP must be less than 50 milliseconds, and the phone must be able to roam from one AP to another within 50 milliseconds.

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Unmanaged Wi-Fi networks

If your organization's users plan to use the BlackBerry MVS Client on a home Wi-Fi network, you should create guidelines to help create a positive user experience. The guidelines should include the following:

  • Specify an expected minimum download and upload speed for home Internet connectivity.
  • If there is simultaneous use of different applications while using VoWLAN (such as video streaming, gaming, and file transfers), turn on QoS on the home WLAN router to make sure that the devices that use VoWLAN have precedence over other endpoints.
  • To reduce the number of variables from interoperability or WLAN router configuration settings, consider creating a short list of WLAN router vendors or minimal versions of routers that have been tested against the WLAN devices that the organization uses.
  • Identify the minimal expected level of authentication and encryption configured on the home WLAN router (for example, PSK with WPA2).

If your organization's users plan to use the BlackBerry MVS Client on Wi-Fi hotspots, you should communicate the following to them:

  • A hotspot WLAN is an unmanaged, shared resource that can impact any application using the WLAN. There is a possibility that congestion, high latency, absent QoS, and restricted bandwidth are all present at the hotspot and therefore the user experience might not be optimal.
  • VoWLAN on a hotspot WLAN might not be possible due to network factors and should not be relied on as a dependable method to make or take VoWLAN calls. If a VoWLAN call on a hotspot WLAN does connect, the voice quality is not guaranteed.
  • Data applications running over the hotspot WLAN can adjust and tolerate a poor WLAN environment, but there could still be an adverse impact on data applications.
  • Security on a hotspot WLAN is non-existent. Communication when using a hotspot should only occur with the use of VPN or other additional security mechanisms, such as the VPN available in the security model of the BlackBerry solution.
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