Testing

Even until several years ago, most of WLAN application is tied up with PC and laptop and the capable throughput and expected is not that high. The range of the testing were not that wide either. Now at the age of Smart phone and many other electronics supporting WLAN functionality, the range of the testing WLAN has been drastically widened. Followings are some of the testing items poping up my mind as of now and the list will get longer and longer as we evolve to 5G, in which WLAN would play even bigger roles in whole communication system.

1. PHY/RF

PHY/RF testing is mainly for testing RF transimission signal quality, reciever sensitity. These are usually tested by WLAN Chipset vendor or WLAN Module maker. It has its own list of test items mainly defined in IEEE specification.

Following is an example of PHY/RF testing system from Anritsu, named MT8862A.

Item 2~6 are usually tested by company who provide WLAN as a complete service like PC maker, Mobile Phone Maker or Network Operators. Usually all of these items are consolidated into a single test package.

2. User Interface

In case of usual laptops/PCs that does not have any cellular communication capability, user interface for WLAN would not be that complicated. Probably only Authentication setup GUI is enough. But in case of mobile phone (SmartPhone), there are many different ways for wireless communication in addition to WLAN. So there are many options for communications and there are more options for WLAN as well comparing to PC/laptops. In addition, the behvaior of WLAN related User Interface may act differently depending on the settings of User Interface of other communication technology. So all the possible combination of WLAN User Interface setting and verification of their behavior become important test items. You would see a lot of test cases just related to this kind of User Interface. Following is one example of User Interface directly or indirected related to WLAN on a mobile phone. You may see different interface on different mobile phones. This is just an example.

Even though this is only User Interface testing, you may need a test system that can support both Cellular technology and WLAN technology because some user interface operations requires the completion of a certain radio protocols.

3. Authentication/Security Mechanism

As WiFi technology evolves, the techniques that tries to break into the security protection mechanism also evolves. As a result, you would see more and more different types of Security mechanisms are used. Since a mobile phone (or laptops) is expected to work with WiFi network anywhere, you should verify that your device can work with all different types of Security system. Following is just an example of WiFi access points that my mobile phone can detect in my office (I intentionally changed the SSID name for information protection purpose :) and you will see various different types of Security algorithms are used ( the security method is indicated on the yellow line. The 'empty' space on the yellow line indicate 'Open' connection (basically No Security at least on the Access point). Of course, this is just an example and you may see even more diverse method where you are.

To test these method, you would need a test equipment that supports all of these security methods and user data connectivity, or you may use your live Access Point.

4. ePDG/IKE

ePDG is a special mechanism to connect a WiFi network (Untrusted Network Component) to a Cellular network at IP data layer. To connect this kind of untrusted component to Cellular network, a special type of authentication and security algorithm is required and in most case IKEv2 are used.  I wouldn't go through the details of how ePDG works. If you want to know further details, refer to WiFi Offload page and IKE page.

As far as I experienced, this started being developed in mobile phone industry almost two years now (as of Jun 2015), but only recently a few network operators started seriously testing in their lab. To test this functionality, you would need an equipment which has at least following components that can simulate both cellular network and ePDG/AAA Servre (IKE) as illustrated below. If you are a person who is involved in this kind of test, refer to WiFi Offload Check List page first.

5. Access Selection between WLAN and Cellular Network

In case of all the mobile phone and some PCs that support both WiFi and Cellular technology, the device has to make a complicated decision whether it should connect to Cellular Network or WiFi network. If the device is connected to both network simultaneously, it has to make another decision when user is trying to make a voice call.. it has to determine whether it initiate call using cellular network or WiFi network.

A certain level of decision is made by the special settings that a user has configure and some other level of decision is made by signal strength between cellular network and WiFi network. But the detailed selection criteria is specified by each service provider (Network Operator) and these selection algorithm is a very important part of testing in most network operators.

Following is one example of UE setting that directs UE on how to select network between cellular and WiFi. This is one of the simplest configuration and you would see much complicated setting if your device support not only data call over WiFi but also voice call over WiFi.

6. Throughput

Conceptually throughput test is simple to understand, but as far as I experienced performing throughput test in WiFi is more difficult than cellular technology because WiFi PHY/MAC scheduling is not as reilable as celluar technology. Because WiFi is scheduling data transfer based on CSMA/CA and random backoff, the throughput test result would be fluctuating drastically if there are any interference in the channel.

At the initial phase of throughput test, we usually test about maximum throughput under ideal channel condition, but recently I saw many company is putting tougher criteria in terms of throughput test condition. The most common criteria about throughput test you may see as of now would be as follows :

• Max throughput under ideal channel condition
• Throughput vs Range (distance between the device and AP)
• Throughput vs SNR
• Throughput vs Frame Fragmentation

7. WiFi HotSpot

WiFi HotSpot is a technology which can translate WiFi protocol into another type of wireless technology (e.g, WCDMA/HSPA or LTE). In some case, we use live network or lab network but in most case we use a network simulator as shown below. In this case, we assume that Cellular part network simulator is performing ideal max throughput but as you might have experienced there is no such a thing like 'ideal'. At the early stage of test system setup, you would need to spend a lot of time and effort to make it sure that the cellular network simulator is working as expected. Once this part is verified, the remaining test method and criteria on WiFi part is similar to 'Throughput' test described in previous section.

8. WiFi Direct

WiFi Direct is a mechanism by which a device can communicate with another device directly without going through AP (Access Point). If you are not faimilar with this functionality, see this video : How to Use Wifi DIrect. If you are more interested in the technical details, refer to WiFi Direct page.

If you want to perform very strict test about this, you would need special equipment that can simulate WiFi device, but I haven't seen this kind of equipment yet.  There might be this kind of equipment which I don't know of.