Home Latin America IV 1997 Base Station Testing: Key to Wireless Network Success

Base Station Testing: Key to Wireless Network Success

by david.nunes
Eric A. MegerIssue:Latin America IV 1997
Article no.:3
Topic:Base Station Testing: Key to Wireless Network Success
Author:Eric A. Meger
Title:Wireless Business Unit Manager
Organisation:Wavetek Corporation, USA
PDF size:20KB

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Article abstract

In any new deployment or expansion of a wireless communication network, the Challenge for any operator is to translate the theory of the Network Design into practical reality. Computer generated coverage plots can bear little resemblance to what is actually experienced by customers. The key to wireless network success is the careful and accurate base station testing. With careful selection of equipment, one can achieve an excellent balance between the competing demands of cost, efficiency, speed and accuracy in any network deployment.

Full Article

In any new deployment or expansion of a wireless communication network, the challenge for any operator is to translate the theory of the Network Design into practical reality. Computer generated coverage plots can bear little resemblance to the reality actually experienced by customers for a variety of reasons. Such problems include incorrect terrain models, poorly chosen software tools, inexperience of design personnel and unmodelled interference from other sources. Even when one avoids or solves these design problems, the network’s performance still depends on factors such as installation craftsmanship, site optimization and equipment reliability. Careful Base Station testing using application specific test equipment is key to avoiding all of the customer-affecting problems that come with a poorly implemented system. Every network goes through three phases of implementation once the theoretical design is complete: Installation, Optimisation and Maintenance/Repair. Even though the distinction between the first two phases can be blurred at times, there are, in fact, very different requirements and challenges during each of the phases. Installation Tip Because of the importance of installation craftsmanship, some carriers require photographs of key elements of the installation (such as cable feeds, connectors, power and signal isolation) along with a detailed site report containing all test results. Installation This first implementation phase is always the most hectic. Under pressure to begin generating revenue from all the expensive capital equipment, operators call in all available resources to get the system up and running. Multiple crews are working in parallel to build each site and connect together all of the boxes, cables, antennas, mechanical bits and pieces at as many sites per day as possible. This is when a great many future problems are created. Connectors and cables must be installed carefully. Poor craftsmanship here is often not visible. Cables and connectors which work initially can degrade over time and cause outages that are extremely difficulty to diagnose. In addition, the crew must verify the RF performance of the Base Station and, if necessary, adjust using a sophisticated Base Station Test Monitor such as the Wavetek STABILOCK 4032. Such a tool not only verifies the functionality and RF performance but can also check for problems with antenna cables using a tracking generator function. Note that new deployments can involve many crews that may not be experienced on the particular base station (it being the latest generation of course). Network operators can maximize productivity, minimize errors and costs by assuring that each crew has standard test equipment and procedures that are easy to use and easy to carry. Optimization refers to careful checking to ensure that the various sites comprising the network actually deliver the coverage promised by the design tools. After discovering a problem using drive-by monitoring, a site visit is usually required. Adjustments to antenna pointing, base station power configurations or mechanical repairs can fix the coverage problem but cause degradation of performance later. Again it is essential the crews verify that the performance of the Base Station meets the required specification using proper test equipment. Much of the cost associated with the optimization (as well as maintenance and repair) comes from the cost of sending a crew to a site. Each visit ties up people, skills and equipment away from other duties. Minimizing the number of site visits is an essential part of managing operational costs. Maintenance/Repair Once the system is operational, the fun begins. In any system there will be failures. With today’s advanced equipment, the actual boxes are both -very reliable and smart enough to report major failures automatically. Does this mean that once a site has been optimised it rarely needs to be tested? The answer is no. There are many causes of network problems that are not major component failures. sometimes the only indication of such problems is an increase in customer complaints. An example would be an antenna that was accidentally misaligned by someone or something unknown to the carrier. Incorrect error reports can mask other, more subtle problems. For example, a rusting coaxial cable connector could cause numerous problems for a transmitter that might report a transmitter failure rather than the original cause. Once a problem appears, a crew must visit the site to make the repair – either immediately or on a scheduled maintenance visit. If service is out or degraded, revenue is being lost and customers are becoming dissatisfied minute by minute. Restoring service fast is the highest priority and every crew knows it. Once service is back up, there is a temptation to move on to the next problem. The crew should perform a complete base station check before leaving the site. Having a flexible test tool such as the STABILOCK 4032 with preprogrammed test sequences can make it easy and fast for the crew to accomplish this without retrieving more boxes from the truck or setting up multiple pieces of equipment. If the process is time consuming or difficult, the crew will be tempted to skip the test and therefore can miss additional problems and force another costly outage and site visit later. In all phases good records are essential. The STABILOCK 4032 can either print or electronically record all test results. Using automatic test programs and data recording each base station will undergo exactly the same tests. Likewise, the tester creates a record for each base station that can aid in analysing base station degradation over time. Conclusion In conclusion, every phase of wireless network deployment requires careful and accurate base station testing. The skill, craftsmanship and dedication of the work crews can make the difference between satisfied customers on a reliable network and escalating operating costs, manpower shortages and increasing churn. Nevertheless, even the most contentious technicians can only be effective if they have the right tools for the job. Test equipment designed for laboratory use are often complicated to use, heavy to carry and require much higher skill levels and training than equipment designed specifically for use in the field. With careful selection one can achieve an excellent balance between the competing demands of cost, efficiency, speed and accuracy in any network deployment.

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