WiFi AP Manufacturing

Enterprise-class WLAN AP manufacturing test today focuses primarily on radio calibration and parameter verification. Post-integration test is relatively low-intensity (compared to RF testing). Even if burn-in tests are conducted, they are done under light traffic load or no load at all. However, key elements such as connectors and antennas can only be verified after assembly; thus functional testing of subassemblies cannot ensure that the assembled product will perform, leading to risk of defect escapes into the field and consequent customer quality perception issues.

Examples of defect escapes that can occur without intensive post-integration test are:

• Interface problems –connector defects, pinched cables, misaligned elements, etc.
• Defects in high-density memories that only show up when the AP is loaded to full capacity (i.e., the whole memory device is loaded at speed)
• Marginal components (ICs, bus connectors) on the main board or radios that fail under full load conditions, e.g., triggered by voltage/temperature excursions

Further, analysis of RMAs, lot qualification, and quality audits on WLAN APs are also complex. These tests are frequently conducted using ad-hoc setups built around laptops and software that are not designed as precise and repeatable test tools. Thus such standard processes are time-consuming, labor intensive, and often inconclusive.

The WaveTest system from VeriWave offers a means of addressing all of these problems. Highly repeatable and controllable tests can be run on fully-integrated APs in a short time to quickly identify failed units on the production line. In addition, ancillary tasks such as RMA analysis and statistical process control can be performed with the same platform.

On the production line, WaveTest offers many benefits when performing post-integration test. It is highly controllable and can load an AP to its full capacity (hundreds of clients and hundreds of megabits of traffic) in test cycles lasting a few seconds. The quantitative results are comprehensive, extremely repeatable and easily interfaced to quality tracking and control systems. The platform is fully automatable and programmable to meet changing process and product requirements. The system can reveal defects during burn-in that only show up under stress. Finally, the WaveTest platform is already being used in the entire R&D chain (from development to QA), so manufacturing issues can be rapidly duplicated and manufacturing test development is greatly simplified. The platform is cost-effective, with a single chassis capable of serving multiple production test stations.

Coverage	Test	Metrics	Test Time
Beacon power, SSID and mac addr, ethernet phy	BSSID Scan	RSSI, BSSID, Link confirmation	15 seconds
Memory, interface connectors, radio throughput (Rx), main board, power supply. Maximum throughput configuration.	Upstream Frame Loss: 20+ clients wifi to 4 Ethernet clients (802.11n, 40MHz, SGI, MCS15) at 1518 byte and 88 byte frames	Forwarding Rate in PPS Frame loss in % 802.11 retry rate in Max and average latency in us	1 minute
Memory, main board , radio throughput (Tx). Maximum buffering and aggregation configuration.	Downstream Frame Loss: 4 Ethernet clients to 20+ wifi clients, 802.11n, (40 MHz, SGI, MCS15) at 1518 Byte and 88 byte frames	Forwarding rate in PPS Frame loss in % 802.11 FCS error rate Mix/max RSSI in dBm Max and average latency in us	1 minute
Memory, main board, radio. Mixed mode/traffic configuration.	Mixed Traffic Fame Loss: 10 802.11n clients, 10 legacy clients, voice, video, background and best effort traffic.	Forwarding rate in PPS Frame loss in % R-value and MDI score TCP Goodput in bits/sec Min/Max RSSI in dBm	2 minutes
Radio reception performance on multiple channels	Low Power Frame Loss: 802.11n client, minimum power, MCS15, checked on multiple channels	Forwarding rate in PPS Frame loss in %	4 minutes (includes changing channel on DUT)

The same WaveTest platform (with different application software) can also be used for customer RMA analysis, outgoing quality audits, statistical sampling, and defect isolation. Short GUI-based tests can be created for the more extensive testing involved in statistical sampling checks and quality audits. The VeriWave Master Test Plan contains several hundred more extensive tests (most of which are fully automated) that can perform rapid “pushbutton” RMA analysis checks. Best of all, the use of a common highly stable, reliable and robust platform across the board simplifies the duplication of test setups as well as creation and maintenance of test processes.