Introduction

Patents related to mobile devices and wireless networks have received significant industry attention as they enable mobile device manufacturers, network system vendors, and cellular providers to protect the intellectual property rights of their most valuable inventions and technological advances.

The establishment of solid evidence of use (EoU) for these patents has become a paramount challenge for the IP industry. However, Ocean Tomo, a part of J.S. Held, (Ocean Tomo) has established an excellent reputation for producing EoU for mobile/wireless patents through deep technical expertise in wireless products and standards and through extensive hands-on experience in functional testing.

This paper provides an overview of our wireless functional testing expertise and capabilities, which help our clients and partners understand the various testing approaches we have at our disposal and how to make informed decisions for their IP programs.

Functional Testing Toolset

In advanced cellular standards, such as European Telecommunications Standards Institute (ETSI) 3rd Generation Partnership Project (3GPP), features are constantly evolving and are often optional within the standards as opposed to essential. In addition, some features may be implementation-specific in that a standard may define an end-result or requirement but not specify how the end-result or requirement is achieved. To add complexity, although terminal and network systems may be “capable” of supporting certain features of the standards, the use of these features (including essential, optional, and implementation-specific features) often depends on the cellular network operator’s strategy and mobile device implementation. As such, relying on the standards documentation as the sole source of evidence for infringement of claims in patents is insufficient. In such an environment, functional testing is particularly useful for establishing EoU in that we can show that the standard’s features are being implemented in user devices and by mobile operators, as opposed to simply being prescribed within the standards.

At Ocean Tomo, our labs include capabilities that allow us to verify the use of standard features regardless of the type of feature, whether essential, optional, or implementation specific. Our toolset of functional test capabilities can be broadly categorized as shown in the table below:

^{Table 1 - Our toolset of functional test capabilities}

Live Network Testing

User Equipment Testing

A first approach in live network testing involves the use of off-the-shelf terminals which are connected, via an over the air (OTA) interface, to vendor equipment such as base transceiver stations (BTSs) that are commercially deployed and configured by the mobile service providers operating the networks. In the type of testing seen in Figure 1 below, the uplink and downlink transmissions between a user equipment (UE) and a commercially deployed BTS are detected in a passive way.

This type of testing has its challenges and limitations. Network equipment behavior is determined by the product software release, and only features which have been activated by the operator can be observed. As such, a priori knowledge of software releases and the activation of certain standard features can be extremely useful. Ocean Tomo has been conducting tests throughout the US, Europe, and Japan and has accumulated a wealth of information on network implementations.

When a UE connects to a BTS, information exchanged between the UE and BTS can become encrypted at the higher layers of the communication protocols. This poses some difficulties which can be overcome by designing test plans that do not rely on the need to detect the encrypted information or by using equipment capable of decrypting the uplink and downlink transmissions between the BTS and the UE under test.

Once these obstacles are successfully overcome by way of a properly designed test plan, live network testing offers valuable insight into the use of patented technologies in commercial deployments, particularly for technologies which involve simultaneous terminal and network interactions.

^{Figure 1 - Functional diagram of the live testing configuration.}

Base Station Testing

When testing BTSs, the challenge often begins with the identification of the vendor equipment to be tested. Cellular BTSs do not send signals with vendor specific “signatures” that could be used to reliably identify the type of BTS or the vendor of a BTS at a particular cell tower. We have developed a multistep methodology that enables our engineers to identify the type of BTS (e.g., macro, pico), the standard supported by the BTS, and the vendor of the BTS at a particular cell tower.

A second approach for conducting live network testing involves the use of an instrumented UE. An instrumented UE is a mobile UE with special software that enables the monitoring of baseband processor protocol behavior. The instrumented UE connects to a BTS in the field, and protocol information can be extracted from the UE. An instrumented UE is a useful tool for testing a vendor BTS in a semi-controllable environment. For patents with claims directed to network devices, such an instrumented UE performs the role of a terminal emulator that can be used to trigger a certain network behavior to verify whether those network devices implement the functionality that is being tested

^{Figure 2 - Functional diagram of a live BTS testing configuration using instrumented UE.}

Captive Testing

Captive testing is mainly applied for testing UEs and makes use of network emulators which emulate the capabilities of a network and enable the configuration of a device with any set of features which are either mandatory or optional to standards. Captive testing offers a controllable environment with the flexibility to create many test cases which may be difficult or impossible to address in live networks. For example, channel fading effects can be controlled easily in a captive testing environment but are much less controllable in a live network. In addition, whereas in a captive testing environment the emulators provide the capability to easily observe encrypted protocol information and control signals, in a live network testing environment this can be more challenging.

For patents with claims directed to UEs, off-the-shelf UEs or terminals are connected to network emulators which then attempt to trigger certain terminal behaviors to verify whether those terminals implement functionality that can be mapped on to claim elements. Some network emulators not only come with software that provides standard test capabilities but also allow a test engineer to create test scripts for “custom” tests, thereby providing a flexible testing environment (Figure 3).

Figure 3 - Example diagram of a test.

Equipment and Test Case Configuration Considerations

Wireless test equipment can be expensive and difficult to configure and operate. Fortunately, the wireless testing industry has evolved along with the standards and cellular networks deployments, and we now have a large variety of test equipment from which to select depending on testing needs. Ocean Tomo has extensive hands-on experience with test equipment for live testing, standards conformance testing, and emulators for testing various generations of cellular networks including 5G, 4G/LTE, and WCDMA/HSPA, and for testing WiFi, Bluetooth, and other short-range wireless networks. This experience allows us to efficiently select the best configuration that meets our clients’ needs.

This solution is not without a set of challenges. For example, one challenge involves configuring the test equipment for the test cases that are required to demonstrate the EoU for showing infringement of patent claims. Each claim in a patent has its own limitations and associated test cases for showing the required EoU. The test cases most often require individual selection of software features, types of test signals, and testing conditions. In addition, test scripts used to test certain behaviors, functions, or capabilities often need to be custom modified to enable detection of the feature of interest.

With most test cases requiring a specific test plan, we have developed an approach in which each case is analyzed, and individual plans are developed for producing the required EoU in a cost-efficient way while minimizing risks.

Example of a Testing Program

In a typical situation a client may have several patents that require functional testing, and they engage us to analyze the claims and propose a testing approach. In other situations, the client may present us with a technical challenge after having performed an in-depth analysis of the claims. In both cases we would conduct a review process and have technical discussions with the client to determine whether testing is required and, if so, the following test program is followed:

• Use case definition.
• Test configuration and test plan development.
• Test execution.
• Test analysis and reporting.

Use Case Definition

This is often the most critical step which determines the success and cost of the project. It starts with a detailed review of the claims to identify the critical claim element(s), which requires testing to produce the required EoU, followed by development of a detailed procedure for testing. Some aspects of the procedure being developed may be validated at this point with the instrumentation intended for the test execution, as part of a test feasibility study. The procedure is documented and reviewed with the client. The effort required for test execution is identified along with any expected risks. Alternative test procedures are established in the event the initial attempt is unsuccessful.

Test Configuration and Test Plan Development

This process involves the selection of equipment, costing of custom testing modifications, and development of a detailed test plan. When the test equipment needs to be sent to a test site for live testing, the test plan includes logistics for travel and shipment of the test equipment. This stage may involve identification of the best site for testing, particularly when vendor specific BTS testing is required.

Test Execution

Test execution involves measurements of signals which carry protocol messages for communication between terminals and base stations (or the emulators). The capture of signals is rather straightforward: in a live testing environment a signal is detected and recorded by the test equipment for a specified time (usually several seconds to minutes), and the measurements are stored for future analysis. It is desirable to briefly analyze the results onsite to determine if the test results contain evidence of a searched behavior or whether the test conditions need to be modified because the information of interest was not found. Since measurements could take place in a moving vehicle (e.g., for analysis of handover between cells) or in a busy venue (e.g., to entice quality of service [QoS] priority in heavy data traffic) where conditions are not all controlled, it is sometimes desirable to make repeated captures and assessments before heading back to the lab for final analysis of the data.

As with fishing, one is not guaranteed to bring back a “catch” at every “cast”; some spots and conditions may be more favorable than others, and some unknowns will remain. Good preparation and systematic execution considerably reduce the potential risks and ensure the success of the measurement campaign.

Test Results Analysis and Reporting

Analysis of the recorded signals is performed off-line using the captured data. Our experts have written scripts which enable them to quickly and reliably sift through the terabytes of collected data (results) and identify the relevant data for analysis. The detailed results are analyzed and included in a comprehensive report. The report contains a description of the methodology used to collect and analyze the test results, a description of the test conditions so that the tests can be replicated in the future if necessary, and the test results.

Conclusion

Ocean Tomo, a part of J.S. Held, brings multidisciplinary experience to the process of establishing evidence of use of wireless-related patents. Such experience includes knowledge of standards, design and implementation of the products, and deep understanding of the patents. Functional testing is one of the key elements in our comprehensive toolbox which we use to assist our clients in demonstrating the value of their intellectual property assets.