Over The Air Programming (OTAP) Part 2

This is the second part in a five part series of posts on Radio Management. This allows system managers to remotely configure radio units without the need of physically touching the radio. Via the Radio Management CPS, configuration updates can simply and quickly pushed to radio units.

In OTAP, there are five high level steps for updating the radios’ configuration:

  1. Initial programming of the essential communication parameters into the radio via wired CPS when it is unboxed (i.e. the baseline configuration).
  2. Populating the CPS Server with the current radio configuration.
  3. Modifying the radio configuration within the CPS Server
  4. Delivering the modified radio configurations to the radios.
  5. Applying (or switching over) the delivered radio configurations.
Steps 3; 4 and 5 would only be carried out once the radio has been put into service – and if any changes are needed.

Prior to the first over-the-air programming operation, the radio must be provisioned with the CPS via a wired connection (USB). All the essential communication parameters, required for the radio and RM to communicate with each other on the system, must be programmed here. This includes things like firmware upgrades (if needed); System and channel parameters; Data parameters; the Radio ID and most importantly, the OTAP authentication key.

The only new OTAP parameter, required in the radio, is the OTAP authentication key and key ID. This must be present in both the radio and in the CPS, prior to the first OTAP operation. The OTAP authentication key can thereafter be changed over-the-air, if the current key in the radio matches the previous key entered via RM (CPS).

After the radios have been initially programmed with wired CPS via USB, their configurations must be populated into the CPS Server. There are three different ways to populate the CPS Server with the current radio configurations:

1.    Archive importing by means of the saved codeplug. This requires a connection to the Radio Management Server but can be done at a later stage once the connection is present.

2.    Radios entered one at a time into RM. Radios can also be entered one at a time into RM. This requires the system administrator to know all identification information of the radio including the serial number, radio ID, common air interface ID (CAI), OTAP authentication key ID and OTAP authentication key value. If populating numerous radios at one time, a Radio Identity File may be used. The Radio Identity File is a Comma Separated Value (CSV) file that contains a list of radios each containing the serial number, radio ID, CAI, OTAP authentication key ID and OTAP authentication key value.

3.    The CPS allows scheduling of multiple radio configurations to be retrieved unattended. The CPS starts the retrieval at the scheduled time and continues until all selected radios are either complete, in error, or have been cancelled. It is recommended that over-the-air operations are scheduled during times of low traffic in order to minimize the impact on system performance.

After importing a radio into the CPS Server, a scheduled over-the-air or wired retrieval operation is required. For large codeplugs, it is recommended to perform a scheduled wired retrieval or delivery prior to the first over-the-air operation to minimize transfer time.

The retrieval mechanism over-the-air supports CPS data and voice to coexist, although system performance may be degraded slightly. The mechanism can also handle radios that enter and leave RF coverage. The retrieval operation utilizes the PN to optimize the delivery.

There are numerous methods to initially populate the CPS Server. Most customers can quickly determine which method aligns the best with their standard practices. The following steps are considered the most optimal CPS Server population method:

1.    Update the firmware (if required) via wired CPS.
2.    Read and save the codeplug via wired CPS.
3.    Import the saved codeplug into the Radio Management.
4.    Assign the proper radio ID, CAI, OTAP authentication key ID and OTAP authentication key value.
5.    Select an appropriate radio template.
6.    Schedule a wired delivery of the new parameters.

After a successful wired delivery, the radio should be completely synchronized and ready for use on the system, and for its next over-the-air programming.

If the CPS Client, Server, and Device Programmer are all on the same computer, these steps can all be performed without disconnecting the radio from the computer. The device programmer should be configured via a wired connection during these steps. If the selected template has enhanced privacy enabled, the enhanced privacy key values must be populated in order for the delivery to be successful.

Once populated in the CPS Server, the radio configurations are modified using the classic CPS interface. A radio entry in the CPS Server references a configuration. The referenced configuration, referred to as a template, can be unique to the specified radio, or can be a configuration referenced by numerous radios. Radio identity information is specific to the radio, while other parameters in the template are shared.

When a radio’s configuration is updated, the status gets updated to “Codeplug Modified”. This means that the configuration needs to be delivered to the radio over-the-air.

If the radio user is allowed to make changes via the radio front panel, it is important to understand that these updates are not retained after a delivery. The configuration in the CPS Server overwrites what is in the radio when delivered. Similar to how wired CPS functions today, the system administrator must read radios over-the-air first, make individual updates to each, and then deliver the new configurations in order for the previous changes to be retained. If using a single configuration (a template) for numerous radios, there is no way to retain any individual changes the radio users may have made. All radios are updated to match what is in the template, with the exception of the radio identity information.

NOTE: Programming radios that are managed within the CPS Server with an unmanaged wired CPS causes the radio to be out of sync with the CPS Server. This causes the next over- the-air operation to take a longer time since the entire configuration must be retrieved or delivered.

It is important to take special care when changing parameters that may break communication between the radio and the control stations used by the CPS Server. For example, accidentally changing the frequencies of the channel used for OTAP communication results in the CPS no longer being able to communicate with that radio. The radio must be programmed via the wire in order to recover.

If changing parameters such as radio ID and OTAP authentication key ID and value over-the-air, the previous known values are used to deliver the new values. If these values become out of sync (possibly due to an unmanaged wired write of a radio), the Reset Identifiers feature should be utilized. Reset Identifiers allows the values used to communicate with the radio (in contrast to the new values) to be set within the CPS Server. If these values are unknown, the radio must be programmed via the wire in order to recover.

As soon as any changes have been made to the (baseline) radio configurations within the CPS Server, their status gets updated to “Codeplug Modified”. This means that the configuration needs to be delivered to the radio over-the-air.

The CPS allows scheduling of multiple radio configurations to be delivered over-the-air in an unattended mode. The CPS starts the delivery at the scheduled time and continues until all selected radios are either complete, in error, or have been cancelled. It is recommended that over-the-air operations are scheduled during low traffic periods (i.e. overnight or on weekends) in order to minimize the impact on system performance.

The delivery mechanism used for over-the-air programming allows for voice and OTAP to coexist, although system performance may be degraded slightly during OTAP operations. The mechanism can also handle radios that enter and leave RF coverage. It utilizes Presence Notification (PN) to optimize the delivery.

The time it takes to deliver a configuration to a set of radios is dependent on the number of radios and the amount of changes since the previous configuration change.

A pacing option is available to add additional delay to the delivery process. This is useful when delivery time is not important and it is desirable to minimize impact on the system performance. The pacing option is set to zero unless manually changed in the CPS Device Programmer.

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