Celona's wireless networks are designed to provide seamless connectivity by taking advantage of overlapping coverage from multiple access points (APs). However, to ensure that the network operates at peak efficiency, it is crucial that the APs are accurately time synchronized.

If the APs are not synchronized, they may transmit at the wrong time, leading to interference with signals from other APs in the coverage area. This can result in issues with handover and throughput, causing significant disruption to the network's performance.

By using time synchronization, organizations can ensure that their indoor wireless network is operating at peak efficiency. With accurate synchronization, the APs are able to transmit signals at precisely the right time, allowing for seamless handover and maximizing network throughput. This ensures that organizations can rely on their wireless network to provide consistent and reliable connectivity, even in the most demanding environments.

To synchronize time between APs, Celona uses the Precision Time Protocol (PTP), which works similarly to Network Time Protocol (NTP). PTP relies on a Grandmaster, a network-connected appliance with a GPS/GNSS receiver, to act as the network time source.

Depending on the size of your Celona deployment, you will receive a GPS antenna or a PTP Grandmaster appliance to serve as the timing synchronization source for APs on your Celona network.

Each Celona AP can synchronize its time using one of four options:

It is possible to designate both a primary and secondary PTP server for the APs to use. If the primary PTP server fails, the APs will automatically switch to the secondary server. The secondary server can be another AP or a local PTP server.

To set an AP to Free Running mode, toggle the Auto-Discovery button under Access Points> Details page of an Access Point once selected from the Inventory table > Advanced Access Point Config to disable the Auto configuration of a time sync source and set Access Point to Free Running. Acknowledge that the AP will reboot as a result of this change and click Yes.

Celona does not recommend Free Running mode in production deployments because of the possibility of time drift between APs.

Free Running APs cannot act as PTP leaders.

Ensure a GPS antenna is directly connected to the Access Point GPS port for GNSS sync to succeed.

Access Points will automatically time sync to the GNSS time source once GPS sync is available after the GPS puck is installed.

Supported Access Points that are successfully GNSS synced will also automatically qualify as a PTP Leader candidate for other PTP Follower Access Points on the site.

A PTP leader AP can have up to 8 follower APs that synchronize their time with the leader.

The signal strength of GNSS satellites can be found once you click on a GNSS synced AP (PTP Leader) on the PTP Leader table under Site Config.

The Precision Time Protocol (PTP) is a widely used protocol in computer networks that provides a mechanism for accurate clock synchronization between networked devices. This protocol is especially important in environments where time-sensitive applications require precise timing, such as in financial trading or industrial automation.

Celona private wireless networks are designed to operate using Time-Division Duplexing (TDD) technology. In TDD mode, available upload and download bandwidth is allocated by time slot. Precise clock synchronization is essential to ensure that the TDD frame structure is maintained and that data transmissions are properly scheduled.

Celona offers GNSS synced indoor/outdoor access points that can be configured to operate as PTP Leaders on the Orchestrator. Each PTP Leader can support up to 8 Access Point Followers.

The PTP Leader obtains time sync via GNSS time synchronization. Once the PTP Leader has successfully GNSS synced, it becomes available as a PTP source for other non-GNSS synced Access Points. This enables the access points to achieve a high level of synchronization accuracy, ensuring that all wireless devices on the network have a consistent and reliable connection.

The Access Point Followers are synced to the PTP Leader AP, which serves as the time reference for the entire network. This allows for a synchronized network that is crucial for time-sensitive applications, such as video conferencing or real-time data streaming. With Celona's GNSS synced access points, organizations can ensure that their wireless network is optimized for performance and reliability.

Time synchronization is essential for maintaining high device throughput and smooth handover performance in private networks. Access Points with GNSS antennas should be installed in locations free from obstructions, ensuring at least 180-degree exposure to the sky for reliable GNSS satellite signal reception. Celona ships outdoor APs with 3-foot GPS cables, recommended for standard installations to maintain accurate timing.

To monitor GPS synchronization status and identify potential network issues, check the Events tab on the main Organization page. Synchronization failures, which can vary from a few times a week to multiple times an hour, signal possible network performance degradation.

Celona supports GPS cable extensions up to 150 feet for greater installation flexibility. For cable lengths beyond 10 feet, it is recommended to use LMR400 or equivalent specification cables.

To achieve accurate clock synchronization in a Celona private wireless network, a PTP Grandmaster device is used. This device is typically connected to the network and uses multiple GPS signals to create an accurate timing lock. The PTP Grandmaster sends timing information to other networked devices, such as access points (APs), which can use this information to synchronize their clocks.

In a Celona private wireless network, the use of a PTP Grandmaster ensures that all devices within the network have synchronized clocks, allowing for efficient and effective data transmissions. This is crucial for maintaining the overall performance and reliability of the network, as well as ensuring that time-sensitive applications can function properly.

Celona has tested and verified the Trimble Thunderbolt PTP Grandmaster Clock. The PTP Grandmaster device is deployed in a suitable physical location that allows connection to your network, and the placement of an outdoor antenna to receive GPS signals.

The Trimble Thunderbolt must be installed and synchronized prior to integration with your Celona network. If you have already completed this step you can move on to Setup external time sync server.

Before starting the configuration of the GM200, connect the GPS antenna, which must have a clear, uninterrupted, view of the open sky.

By default, the GM200 will ship with the Management port (Eth2) set to IPv4 address 192.168.2.250.

With the management interface settings complete you can move on to set Ethernet Port 1, which is the port used for PTP network traffic. Once configured and saved, connect Ethernet Port 1 to your LAN.

Next, select Synchronization Management from the left-hand menu.

Once all your settings are saved you can check the status of GPS Synchronization by selecting System Status > GNSS from the left-hand menu. The image below shows a successful synchronization.

Your Trimble Thunderbolt is now ready for use with the Celona network.

The first step is to add the available PTP Grandmaster information to your site. Log in to your Celona Orchestrator account, and select Sites > Config from the left-hand menu.

Click the 'ADD' icon to add your external time sync server.

Give your local PTP server a name, and enter the IP address and select the appropriate Packet Rate. The recommended configuration is - Up to 16 APs @ 128 packets per second.

Also confgure the Domain Number for the PTP server, Domain Number (default) is 44 if only one PTP GM is configured on the site, if multiple PTP Servers are configured, please configure a unique Domain Number for each PTP Server (the same Domain Number must reflect on the Trimble PTP GM too). Typically domain numbers for multiple PTP servers are 44, 45, 46... and so on.

Click Add to save the configuration. The PTP Leader will now show up on the table below.

Clicking on a PTP leader in the PTP Leaders table shows a detailed view. For Internal leaders (GNSS Synced APs), the view shows the list of PTP followers along with time sync statistics. It also shows the latitude, longitude, number of satellites, along with a list of the satellites.

IMPORTANT: Any changes to Timing source (External PTP GM or GNSS synced AP) settings will cause all APs using that timing sync source to reboot and begin the synchronization process again. This can take between 15 to 30 minutes, during which time APs may be offline. Therefore we suggest that any updates to timing sync settings are conducted outside of normal operating hours.

Multiple PTP Leaders can be added to the network for redundancy, following the same process to add each PTP device. Once your PTP devices are added to the system, go ahead and configure each AP with the appropriate PTP servers.

Once you click on one of the added PTP Leaders on the table, the details table for this leader opens up as below.

IP Address - IP address of each PTP Follower

Time Sync Status - Time sync status of each PTP Follower that has this leader configured.

Time Offset - RMS/Max - Time Offset in PTP refers to the difference in time between a Follower's clock and the Leader's clock. The goal of PTP is to minimize this offset to ensure all APs in the network have synchronized clocks.

Frequency Adjust - It is the process of fine-tuning the rate at which a Follower clock ticks to keep it in sync with the Leader's clock. Small adjustments in frequency ensures that the Follower's clocks remain as accurate as possible over time, minimizing the accumulation of errors and also reduces the risk of clock instability, ensuring smooth and precise synchronization. It is represented below in unit: parts per billion

Delay - It is the amount of time it takes for a message to travel from the Leader clock to one of the Follower clock over the network. Delays introduce timing errors, which can affect the precision of synchronization between clocks. To achieve accurate time synchronization, these delays need to be measured and compensated for by adjusting the clocks accordingly. A higher delay value indicates jitter in the enterprise network.

You can also confirm PTP client status via the Trimble GM200 (Grandmaster) web interface by selecting System Status > Timing from the left-hand menu.

The PTP client IP addresses should reflect those of your Celona APs.

Monitor the status of PTP sync directly from the Access Points page, as shown above, status message definitions are listed below.

Celona PTP Network Guidelines and Best Practices