A Smart Move
The introduction and rapid growth of smartphones within the wireless market has created congestion problems in networks around the world. New smartphone applications have increased data traffic, and have also led to signaling and overall network issues. To help ensure quality in this unprecedented time of high-bandwidth, high-capacity applications, drive-test systems have long been the gold standard for generating coverage maps.
Drive-test systems perform periodic measurements of service available and quality, and troubleshoot reported problems. But conventional drive-test systems have some significant limitations, including their relatively high cost. Also, they are cumbersome to use indoors, where most mobile usage occurs, and need a highly skilled operator, usually an engineer.
Drive-test systems that run on smartphones provide a full range of measurements indoors or outdoors at a considerably lower cost. The latest generation of smartphone based drive-test systems can be configured to begin collecting data as soon as they are turned on and automatically upload data for analysis at a central location. They also integrate with protocol analyzers so that problems identified by the smartphone application can be quickly checked to see if they are caused by signaling problems.
What’s Driving It?
Conventional drive-test systems utilize powerful receivers that can provide extremely accurate measurements on the performance of a wireless network. Conventional drive-test systems have long been, and will continue to be, the primary tool for capturing the widest possible range of high quality data for efficiently deploying and optimizing wireless voice and data networks.
The latest generation of drive-test systems supports both user equipment device measurements and multi-band, multi-technology receivers to optimize and solve network problems. Drive-test systems are typically used during network deployment to create coverage maps, after deployment to measure network performance along regular routes to detect problems, and also on an impromptu basis to diagnose problem reports.
Many carriers are now involved in deploying and optimizing more complex LTE networks, making drive-test systems more important than ever. But the changing nature of today’s networks has exposed certain limitations in conventional drive-time systems.
Currently about 70% of voice and 90% of data traffic originates indoors. Indoor use already generates the majority of customer problem reports, and this number is increasing.
Yet the size, weight, and complexity of traditional drive-test systems mean that they are nearly always used within a vehicle. You can’t drive a vehicle into an airport, office building, or shopping mall, so it’s difficult or impossible to make measurements in the places where the majority of mobile devices are used.
Drive-test systems are also considerably different than smartphone devices, which sometimes make it difficult to replicate and understand the issues experienced by users on smartphones.
Not Your Father’s Smartphone
Smartphone-based drive-test systems first appeared on the market several years ago. The portability of the smartphone-based drive-test systems is a key advantage. Users can travel through buildings or other areas that are off limits to conventional drive test systems. When the smartphone is being used outside, data can be geolocated using the internal global positioning system of the handset or an external Bluetooth device. That said, it’s also important to point out that smartphone-based drive-test systems cannot match the accuracy of receiver-based drive-test systems.
The first generation of smartphonebased drive-test systems offered support for 2G and 3G networks, and the ability to store the data they collected on to the phone. Typically, the user went out and performed measurements and then returned to a central location where data was uploaded to a computer and analyzed to evaluate network performance. The user interfaces on these early devices were usually simpler than traditional drive-test systems, but they still required a fair amount of skill to operate, so engineers or highly skilled technicians typically used them.
The latest generation of smartphone-based drive-test systems takes this basic approach to a higher level. The latest generation supports LTE, the network technology that delivers the exponential increases in data traffic that the market is demanding. The user interface of the latest smartphone-based drive-test systems has been simplified to the point that a skilled user is no longer required. The device can be programmed to start collecting data when the phone is powered on, allowing users with no experience to perform tests and collect data.
Where GPS reception is not available, the latest devices are equipped with an indoor data collection tool that makes it possible to create input indoor layout plans and point to the location on the layout when capturing data. Cell phones are also expected to, in the near future, begin incorporating indoor positioning systems utilizing a variety of motion sensors -- these will provide an automated method of accurately locating measurement position.
The typical device automatically tests and provides data reflecting performance of voice calls, file transfer uploads, downloads, and browsing. After completing the tests, the phone uploads the data to a File Transfer Protocol site. More experienced users can view test results in real time and replay the data for fast troubleshooting in the field. Wireless carriers can use these devices to monitor performance and replicate issues on the same type of device their customers’ use, enabling them to measure the real end user experience and deploy a more competitive network.
Smartphone Tests Complement Drive Tests
As an example of how these new capabilities can be put to use, a wireless provider hired students to capture data in a stadium during the Super Bowl. The students were seated in positions around the stadium to provide details of data and voice tests at these locations. Engineers at the network operations center who made adjustments to network parameters to improve network performance at the stadium during the event immediately reviewed the data. The portability and low cost of the smartphone-enabled drive-test system made it possible to provide complete test coverage at a minimal cost while freeing engineers from data collection and enabling them to focus on corrective action.
The latest smartphone-based drive-test systems integrate with signal analyzer/call trace applications that can be used to closely examine signaling issues that often are the root cause of quality of service problems. The latest generation of smartphone-based drive-test systems enables users to quickly call up the signaling data for any particular call by setting data capture filters to match the subscriber’s traffic. The call trace application displays message sequences in multi-segment message flow diagrams. Users can follow control messaging as it flows across multiple network elements to identify messaging sequence and discontinuity errors.
A new generation of drive-test systems running on smartphones can complement drive-test systems by providing a substantial subset of their capabilities on much less expensive, easier-to-use platforms that can provide measurements indoors or outdoors as needed. These devices allow data to be captured by less skilled people or even unattended while the results can be uploaded and evaluated by more experienced engineers who can see the data from multiple devices to quickly identify the root cause of the problem and implement a solution.
Graham Byars is a product line manager in JDSU’s Communications Test and Measurement business segment. He has more than 25 years of experience in the IT and telecommunications industry, developing solutions for wireless and wireline networks. For more information, visit www.jdsu.com.
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