Dropped calls are frustrating, but connectivity issues are much more serious if you are a police officer trying to check a license plate against an online database, a merchant trying to complete a credit card transaction on a mobile device, or a field technician attempting to download critical information to repair a piece of equipment.
Solving connectivity problems can be one of the most frustrating aspects of a mobile deployment. There are a number of things that can cause connectivity problems. Network coverage is an ongoing issue, and the carriers are still in the process of building out their networks beyond large metropolitan areas. Changing network conditions can also lead to dropped sessions. “This can be a result of poor received signal strength (RSSI), reference signal received power (RSRP), interference as indicated by signal to noise ratios (SiNr), reference signal receive quality (RSRQ), and changes in latency,” says Joe Savarese, CTO of NetMotion Wireless.
Too Much Data, Too Little Bandwidth
Antennas may be poorly designed or placed, causing weak or interrupted signals, and modem performance can vary by device vendor. Data congestion could also be the problem; this is usually the result of poorly designed or faulty applications, rather than an issue with the actual wireless network. Users may be too far from the cell site, resulting in a weak wireless signal. Natural obstructions (such as mountains) can cause problems, as can man-made obstructions (like very large buildings). Another common culprit is a mismatch between the network bandwidth and the data being transmitted.
“While symptoms such as dropped sessions are often blamed on bad coverage, the root cause is very often too much data over limited wireless bandwidth,” says Jim Christofferson, VP of business development at ConnectRF. For example, transferring HTML documents or large image files over the network eats up much more bandwidth than text/character-based information. “If the user is in an area where there are large numbers of other active cell users, many will likely experience an endless wait wheel that eventually times out or drops the session. Most users will blame it on poor coverage, when the real problem is that there is simply not enough bandwidth.”
When a connectivity issue arises, most users immediately contact their carriers to complain. But the carriers have a limited view of their own coverage, and often the network isn’t even the culprit. There are a number of diagnostic tools now available to help determine the root of wireless connectivity problems. “This is something that an enterprise can purchase and run for a period of time to measure the number of dropped connections, speed of data transfers, and signal strength of various wireless carriers,” says Broc Jenkins, M2M business development manager at Wilson Electronics. “This information can be instrumental in making decisions regarding which carrier to use, and whether or not additional hardware or software is needed.”
Zeroing in on the Problem
These solutions allow users to view device performance, the routes the employees are taking, the equipment being used, and the actual coverage and interference in areas where the field force is working. Look for a tool that can separately record and display the response time of the application and the mobile device for every transaction, as well as one that can separately measure the performance of the wired and wireless sides of the network. That makes it easier to pinpoint the bottleneck, and determine whether the device is failing to respond, or the host application is experiencing a problem.
Christofferson cautions against wireless network performance tools that are installed on each mobile device. “Data provided by a tool that resides on the mobile device will be colored by the point of view of the device,” he says. “The tool is best placed on the wired side of the network in front of the application, to give it an unbiased view of each transaction.”