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Improving Network Reliability

January 23, 2013

The DAS and Mobile World Converge to Help Reduce Maintenance Costs

It’s no secret: 40% of a network’s operational costs are related to maintenance, so it shouldn’t be a surprise that reducing the impact of network maintenance activities is a huge budget savings.

As networks grow and evolve with new technologies, maintenance has become more complex and expensive than ever.

With the huge increase in data usage, the traditional macro network is no longer sufficient to attract new customers or keep loyal, mainstay users happy. Now, more than 70% of all calls originate or terminate within buildings.1 This has led to Distributed Antenna Systems (DAS) becoming a required extension to the macro environment — not just a luxury. The complexity of managing indoor systems can be enormous. They must not only meet customer expectations for availability and reliability but also operate seamlessly with the macro network. Maintaining an economic balance between customer expectations and the maintenance budget is a difficult chore.

Highly skilled technicians and engineers are needed to adjust many network performance factors. Key Performance Indicators (KPIs) are constantly monitored like a roadmap. Each bit of information gathered throughout the entire network tells the team what must be done to keep the customer happy. Reducing turnover from that constant flow of customers, who, for whatever reason, decide to terminate services only to become a new customer of the competitor, is not taken lightly — it’s a critical job performance measure.

Indoor systems are the next crushing wave in the mobile communications industry. The demand for high-quality data services is enormous. It threatens to bring networks to their knees unless carefully managed. Traditionally, management means more resources that must be deployed to ever increasing venues in need of analysis and adjustment, but it’s clear this scenario cannot continue.

Remote Monitoring and Control
The ability to remotely monitor, troubleshoot, and control an in-building wireless system is critical to reducing network maintenance costs. Drastic increases in skilled technical staff, vehicles, test equipment, and even maintenance spares can and should be avoided. The network budget can be better controlled, thereby diverting resources elsewhere.

Mobility is not just for the external customer. The internal customer is just as important if not more. Maintenance personnel should be able to work from anywhere at any time. This concept is not new; it’s common throughout the macro network. The question should be answered then: why has it not been common among DAS designs? The answer is system maturity, rapid growth, and standardization.

System maturity can be closely tied to evolving Airlink standards. As the demand for data explodes, new technologies have been developed to better support that demand. Unfortunately, legacy systems cannot just be turned off like a light switch. A deliberative integration must carefully create coexistence until the network can someday become a common technology platform. UMTS Long Term Evolution (LTE) typifies this situation. Interference created by adjacent channels coupled with intermodulation products are just a few of the technical complexities that are in a constant state of flux. No network is static. It is morphing with a life of its own that mirrors the customer base. Vintage DAS installations must coexist and adapt to the new technologies as well.

DAS deployments are increasing with geometric pace. The public has a need for both speed and coverage. Unfortunately, the two objectives are separate but intertwined problems, especially in large public venues.

Finally, there is little standardization among base station and DAS vendors. Regional networks are usually based on a single Original Equipment Manufacturer (OEM) because of equipment interoperability issues. The same reasoning prevails within DAS deployments. Wireless service providers (WSPs) cannot afford to put all of their technology requirements in the care of one manufacturer though. Equipment diversification is essential to control budgets without overwhelming the maintenance efforts by introducing too much complexity.

The situation previously described creates a unique intersection point: a common boundary of old and new signal sources coupled to old and new DAS infrastructure. Carriers have recognized this boundary and the necessity to condition signals at this juncture in order to effectively manage the indoor network. However, static control is no longer sufficient. Constant change implies constant monitoring, control, and flexibility.

Active DAS Remote Monitoring and Control
Consider a professional sports stadium that desires to improve coverage, increase capacity (the amount of simultaneous traffic that can be serviced), and enhance the fan experience by enabling faster and more reliable data services. Assume the stadium’s current coverage is provided by distribution of fifty sectors originating from two wireless service providers. A sector is an evolved term that stems from
a radio channel’s footprint surrounding a macro radio tower. The offered capacity by a sector is determined by the Airlink technology (CDMA, LTE, UMTS, GSM, etc.) times the number of channels within the physical coverage area. In the proposed example, both WSPs provide channels in the 850 and 1900 MHz bands, but the system requirements have grown to include the following:
1. A third WSP having channels in the upper 700, 850, and AWS bands.
2. The first stadium incumbent is “refarming” LTE coverage to an AWS band.
3. The second stadium incumbent is adding coverage at the lower 700 band.

Clearly this situation is a challenge — enough to make any system performance engineer tear out his/her hair. If the starting signal combinations had been done passively by the use of static conditioning, the common intersection point defined earlier would need complete rewiring which is meticulous, time consuming, and an expensive process. This situation hasn’t even addressed the space requirements.

An active DAS conditioning capability has several distinct advantages:
• Space requirements are minimized: important because in-building space is a premium and an ongoing cost to the WSP.
• Modularity: offers the flexibility to add bands and respective channels as required, minimizing the need for precise forecasting, vision, and deferring expenses.
• Built-in test fixtures and software: allows most frequently used measurements such as spectrum analysis, interference assessment, and power measurement.
• Alarming: measurement limits can set to trigger alarms when issues arise.
• Remote access and control: offer convenience and mobility.

Another advantage of remote access and control can be observed in the cost of commissioning a system. A smaller team can optimize a system more efficiently because source signal control can be quickly accessed from within the venue. The effects of signal changes (e.g., presence or absence, power level, etc.) enhance the commissioning process, leading to an increase in Quality of Service (QOS).

Evolved Network Management Solutions
Strong management systems enable service providers to improve the total network reliability by allowing users near real-time access to a broader spectrum of information via a laptop, smartphone, or tablet. These approaches in combination with active DAS capabilities help limit the operational expense of unnecessary truck rolls. Operators can maximize the performance and reliability of multiple systems by remotely collecting a broad array of metrics.

Remotely accessible equipment hubs such as that offered by active DAS conditioning trays afford service personnel a window into focused statistics. These intelligent trays provide users the ability to monitor RF power, uplink noise, and real-time spectrum analysis via an integrated spectrum analyzer. Having this ability to view key performance indicators is invaluable to RF managers and technical personnel who must diagnose, remotely troubleshoot, and control the indoor system to ensure optimal DAS and macro network performance. More importantly, near real-time action can be executed in response to dynamic environments.

The macro and DAS networks have merged, and adjustments made to one system often affect the other due to their complementary offering. The ability to remotely monitor, troubleshoot, and control a wireless infrastructure is critical to the commissioning and maintenance of a reliable network. Gone are the days when a company has to incur the expense of unnecessary site visits. In today’s mobile world, the ability to remotely monitor an in-building DAS network is easier than ever with web-based management platforms. These platforms enable service providers to improve network reliability by allowing users to remotely access information via a laptop, smartphone, or tablet.

Not only do such developments limit the operational expense of site visits but they allow operators to maximize system performance by remotely managing key system performance metrics including dynamic power, power level alarms, input and output measurements, gain, and user preferences and permissions.


About the Author
Paul Cuda is Director of Business Development and Technical Planning for Cellular Specialties, Inc., a division of Westell. Paul has 30 years of experience in the cellular industry, working for Bell Labs, NYNEX Mobile, and CSI. For more information, please email or visit