Today’s converged mobile devices integrate an increasing number of cellular and connectivity technologies as their functionality reaches beyond the scope of communications and into the realms of information and computation. A state-of-the art handset reaching the market today supports legacy and emerging cellular technologies. Furthermore, a number of connectivity technologies are typically included such as Wi-Fi for wireless local area networks, Bluetooth for personal area networks, and GPS for location based services, among others.
Each of these radios has to be calibrated and functionally verified in production, to make sure that every handset that leaves the production line meets the requirements. RF testing today constitutes a substantial and growing part of the manufacturing cost of a mobile phone. For chipset companies, support for fast and efficient test solutions is becoming just as important as end-user functionality and performance.
Non-signaling testing: the only real answer for multi-radio testing?
Today, most chipsets support so called non-signaling testing, where the slow signaling over the air interface involved in setting up a voice or data call is efficiently replaced by direct commands from the control PC. Non-signaling testing does not require full signaling stack and has been promoted primarily for three reasons:
• reduces test time
• reduces boot up time at manufacturing
• reduces cost of test equipment
A huge advantage of non-signaling testing, which has been overlooked, probably because it is not supported by traditional test systems, is that it facilitates parallel testing of multiple devices. There is no need for the continuous negotiation between the handset and the test system which takes place during a regular signaling call setup to determine the radio configuration of the handset. The same downlink signal can feed multiple devices at the same time. Furthermore, the control PC can send the call setup commands and handover commands to all devices concurrently.
Parallel DUT testing: the faster and effective measurement approach
Parallel testing is instrumental not only when the setup time between measurements is long, but also when the time to do the actual measurements is long. For mobile devices especially, the receiver tests are very long. A test system which can broadcast the downlink signal to several RF ports, and rapidly can switch the RF ports to capture the signal from the different DUTs can dramatically decrease test times as well as increase the utilization of the expensive test systems.