Multi-DUT PXI approach reduces small cell manufacturing cost: Page 2 of 7

November 24, 2014 //By Thomas Deckert, National Instruments
Small cell base stations are a key technology that will increase capacity and coverage of today’s cellular mobile networks. In fact, the growth in the small cell industry is creating a new cost structure of base station manufacturing test.
A number of engineering challenges arise from testing small cell base stations in a high-volume manufacturing environment – and one of the largest concerns is the cost of test.

A big factor in lowering test cost is to increase test throughput. Increase in throughput improves overall production output – and one of the most basic ways to improve throughput is to use high-speed test equipment. Another important factor test engineers should consider is how much their test equipment is utilized.

Utilize your equipment

One of the most important first steps in optimizing a manufacturing line is to better utilize test equipment. In typical manufacturing test of traditional base stations, expensive components such as spectrum analyzers, vector signal analyzers and generators frequently sit idle for long periods of the time. One of the first steps to maximizing test equipment utilization is to use advanced test executives such as TestStand to implement optimized test procedures that allow pipelined, quasi-parallel testing of multiple devices. To fully appreciate the importance of this approach, let us first have a look at the steps taken in typical manufacturing test and then consider specific aspects of multi-DUT testing in more detail.

Anatomy of a typical manufacturing test

Each produced base station goes through a series of manufacturing test steps that characterize and verify the device (Figure 3). First, the test stand operator loads the unit into a fixture, where the device boots, and may perform a self-test or load firmware. The next step is to calibrate the RF frontends. Then, typical RF transmitter and receiver tests verify items such as delivered output power, frequency error and linearity against specified limits to produce a pass or fail verdict.

Figure 3: Phases in small cell base station manufacturing tests and typical relative duration.

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