What is a Drive Test?
Drive Tests are essential for measuring and assessing a mobile radio network’s coverage, capacity and Quality of Service (QoS).
They involve the use of specialised electronic equipment that measures the mobile network air interface. This can be either installed in a test vehicle or used as a portable device.
Drive Test systems can be operated manually, remotely or automatically, along a pre-defined route. They can collect and record information relating to a network’s service in the given geographical area they are testing. Results can then be used to measure the Quality of Service (QoS) against a set of pre-determined KPIs, as well as for diagnostic and troubleshooting purposes.
When to carry out a Drive Test for railways
The initial test & measurement of a rail telecoms network normally takes place at the installation and acceptance stages, using a Drive Test system.
Even before installing the network, it is important to make sure the frequencies to be used are not affected by interference from third parties (band clearance).
During the installation phase, first coverage and network accessibility tests are performed. This is followed by reliability testing while moving across the network.
Eirene SRS and FRS together with O-2875 and Morane are key rail test specifications that are often used. These are normally met by the telecom vendors but it is key for a railway operator to know exactly which specification/standard the network is compliant to.
Drive Tests & ETCS
In case of ETCS level 2 or 3, testing to meet other additional specifications is usually required. Typically, before even setting up a service, the telecom network must be capable of meeting the robust specifications; Subset 093 and UIC specification for Quality of Service O-2475. Both need to be passed and usually require formal Notified Body (NoBo) approval.
To comply with these specifications, it is not possible to use any device to carry out the tests. Testing needs to be conducted using the right type of radio (same power class of operational radio) with antenna placed at a specified height, which usually means on the roof of a train.
Meeting the KPIs requires getting the right number of samples compliant to the specific thresholds. Some KPIs are pretty demanding in terms of the sampling required and since moving a train is expensive, a well specified and equipped Drive Test system can make a big difference in efficiency and effectiveness, so can accordingly save both time and money.
One size Drive Test does not fit all
There is no such thing as one perfect solution for all circumstances. The right Drive Test system is needed for each situation. Dedicated test trains can provide the facility to permanently install Drive Test equipment, including options for unattended and remote management.
However, in many circumstances a transportable solution can be more suitable. For example: if tests need to be carried out less frequently (so it is not worth a permanent installation), when using commercial trains (where equipment cannot be permanently installed), or when tests have to be conducted in multiple locations within a short space of time (where a test train might not be practical).
It is extremely important that each kind of system should be equipped with the right type of radio, scanner and other systems necessary to meet the specific type of test(s) required.
Once acceptance is passed, it is equally important to conduct regular ongoing monitoring, to ensure the network continues to meet its operational KPIs.
Ongoing Drive Tests for operational lines
A process of ongoing network monitoring & troubleshooting should be established as an integral part of daily operations and maintenance. Critical situations can occur if there are issues with interference or equipment failure when a rail line is operational. When systems fail, the ground-train communication can potentially cause train stoppage and delays. This can be critical when operating at high levels of utilisation with many trains running every hour. The ability to source and pinpoint issues quickly, efficiently and effectively can be vital to maintain continued train operations