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People responsible for managing telecom networks dream of the day when all the information that their networks generate can be thrown into a hat and then, like a magician, they can pull out whatever they need, whenever they need it – a list of radios that need tuning, the customers most likely to churn next week, or a list of call destinations that are being misrouted. Much of the data that is thrown into the hat, gets swirled around, and then pulled out in a different form belongs under the cloak of network management. This is a flexible term that is defined differently depending upon who you are talking to, and what stage of sophistication the network is at.
Network management feeds on the raw data generated by countless intelligent devices that are part of wireless networks (e.g. base station controllers, radio transceivers, MSCs and HLRs) or monitoring devices that are attached to network elements or to network connections. The amount of data increases as networks get larger, busier and the equipment becomes more sophisticated.
Reporting of information is not fully standardized, so network management companies have to provide probes, which are modules (usually software) that can interpret the stream of data from each particular device, and turn it into an intermediate form prior to digestion by their network analysis routines.
A considerable amount of filtering, reduction and combining of data is necessary because of the huge volume produced, but also because small amounts of data from different pieces of equipment may, together, tell much more than when they are examined individually. Only a system that understands the topology of the network can tell which pieces of data should be combined, which should be kept as individual items, and which should be summarized.
It pays to ask why network management data should be collected. According to John Kairupan, Sales Manager for TTI Telecom, network management has become an integral part of profitability. This is because a properly managed network will not only keep its customers happy, but it will be able to balance its inputs of resources. Knowing when to send a crew out to a cellsite to prevent a major outage can save a major account, and when there is one crew available and two cellsites in trouble, it is important to know which one is going to have the biggest bottom line impact if it goes out of service.
Network management is usually visualized as a pyramid (See Figure 1). At the bottom is data originating from ‘managed elements’ – devices that are intelligent enough to report data when abnormal events happen (‘alarms’) or, for monitoring purposes, on a regular basis. This data is fed to the element management layer, which can interpret the data and thereby reduce the number of interfaces that upper layers have to deal with.
The element management layer is still dealing with fairly low-level events. It is up to the network layer to map them onto the network topology and assimilate them into more meaningful terms. Filtering and consolidation of data is very important. If an alarm is reported 100 times, it may be meaningful, but humans certainly do not want to see all those occurrences streaming by on their screens! The network layer may be able to examine them, conclude that a microwave link is noisy and change its status on a screen, perhaps generating a single alarm once a threshold is passed.
Higher levels in the chain of network management are more recent additions, and will become even more important as beleaguered telecom carriers attempt to retain the faith of stock markets by squeezing every drop of profitability out of their networks. The business layer attempts to correlate network data in terms that are important to the business, such as revenue being generated by the network and losses created by outages. Looking at the network in this way encourages prioritization of problem solving based on the financial impact to the company.
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There is no point in gathering and condensing network data if nothing is done with it. At some point, the system will detect an anomaly and a piece of equipment will need to be taken out of service for maintenance or replacement. There is some disagreement over whether this process should be manual or automatic. Raghu Shankar, Marketing Manager for ADC Metrica was adamant that customers want to have information presented to them in an actionable form, but wanted a human to press the button to initiate a reaction. John Kairupan, Sales Manager for TTI Telecom disagreed, believing that automatic reactions are necessary, but that often a human would be asked to give their “Go”/“No Go” approval to the action suggested by the network management system.
Both answers are probably right. Systems are far too complex for humans to fully analyze. Semi-formulated decisions, at the very least, must be presented to humans. On the other hand, no software is yet smart enough to completely take over running of the network. Only a human is going to know that the home team just won ‘The Cup’ and everyone in the city has just whipped out their cellphones to call their buddies, overloading all cellsites near the stadium.
Figure 2 is a simplified view of the circulation of data within the network management domain. Information about new problems is continually bubbling to the top. Decisions are made by humans and their machine assistants, and information flows back down to help mitigate or rectify the problems.
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Call Detail Records represent a huge source of additional data – one that is much more customer oriented than information produced by managed elements. Some companies specialize in analysis of this data, that can be used for much more than billing and fraud management. Barry Murphy, CEO of Openet Telecom emphasized that it is important to intercept and analyze call detail records (CDR) prior to their use for billing, as much of the information needed for network management is superfluous for that purpose. By doing this, not only can companies like his provide a consistent interface to many different CDR formats, but they can filter the data for network management purposes, as well as for other purposes such as churn management. Information about the problems being experienced in calls can refine the interpretation of problems reported by the network hardware.
Datalinks do not generate information about themselves. Only the devices connected to the links can do that. Well, that is not quite true. Some companies, notably Agilent and Coherent Networks, specialize in passive monitoring equipment that watches every bit flow across the network, decoding the protocols and monitoring for packet errors and retransmission. In the case of SS7 links, monitoring can occur to the top of the protocol stack. Daniel Doherty, VP Sales for Coherent, notes that this allows diagnosis of problems based on point-to-point traffic analysis. Situations can occur when every call from a wireless carrier to a certain destination is failing because of a provisioning problem in an intermediate network. Without the ability to monitor at this level, the problem would have to be discovered by analyzing customer complaints.
It is increasingly common for major clients of wireless networks to have Service Level Agreements (SLAs). These describe the minimum level of service that the carrier is expected to provide, and failure to abide by the agreement usually results in billing discounts. Carriers have a greater incentive than ever to keep these valuable customers happy. An SLA may be embedded in an agreement to maintain a virtual private network (VPN).
Smart carriers do not monitor service level agreements as an output of the billing process because then problems are detected only in time to pay discounts to customers. Intelligent network management systems should monitor SLAs continually, alarming not when the agreements are violated, but when they are in danger of being violated. Even if there is a violation, it is better to be proactive and let customers know when the problems occur, rather than letting individual complaints flood customer service. An internal company email, warning employees of a major network customer that service disruptions are being experienced due to problems with a cellsite, is far preferable and far less frustrating than unexpected and unexplained problems.
SLA monitoring can utilize information from CDRs to identify groups of subscribers that are being hit hardest by problems, as well as the network topology. A cellsite serving a business park may, for example, have much more effect on SLAs when outages occur than a cellsite in a more residential area.
RF Optimization would seem to be outside the scope of network management. It is after all, something done by specialized engineers with colored maps on paper or on high resolution screens. Channels are grouped by frequency and apportioned in the way that maximizes capacity and minimizes bad things like interference. However, according to Israeli company, Schema, this is all wrong, and optimization is a continuous process that is an integral part of network management. Radio channels are simply network resources (albeit some of the most precious) and every last drop of useful information should be extracted from the mound of data that is generated on a regular basis, or through routine monitoring activities.
There is a lot of data that comes out of element management that reflects radio problems. A lot of dropped calls on one channel could indicate uncontrollable interference, for example. It might make sense to remove that frequency from that cellsite and move it to another. Other information comes from the traditional technique of drive-testing, although this is not always reliable, because drive testing usually is done when the network (and roads) are quiet, while the system should be optimized for use during the busiest times of the day. Schema can also get information from mobiles themselves. Digital mobiles have the ability to monitor the signal strength of multiple cellsites in a process known as mobile-assisted handoff (MAHO). Being able to use this information is like having thousands of drive testers who are most active during the busiest times and, best of all, do not know that they are testing, so do not have to be paid! Schema would not describe how they know where the mobile is, which is obviously necessary to identify places of poor coverage.
Schema takes all this data and, through analysis, can not only identify problems in the network today, but predict where problems will occur in the future, and identify where new channels should be placed.
Many companies view network management as a product: A set of software and equipment that allows carriers to monitor their networks. However, for some carriers, network management is a service that they are happy to contract out. Fredrik Winterlind, VP Business Management & Marketing with Ericsson describes how they first work with the customer to define their rules and policies and then build what they describe as a service assurance system to match. Under circumstances like these, even a big equipment vendor like Ericsson has to be able to work with multiple other vendors, even those that are normally fierce competitors, in order to be able to provide a seamless system to their customers. This mode of operation, according to Winterlind, is particularly common for carriers that are new in the business, or those that anticipate being acquired before being in business for too long.
According to Lisa Ludwig, Director of Product Marketing for Ericsson, 3G systems raise new challenges for network management, not only because of the new technologies involved, but also because of the integration (or collision) of two world views – telephony and data communications, neither of which understand the other.
Network management allows the more efficient use of the capital investment in a network. Gone are the days when the stock market was willing to buy into any plans for new networks. Company executives are now much more focussed on generating money from within or reducing losses, both of which network management can make a big contribution to. And, if congressional representative Anthony Weiner has his way, the US government will start regulating service standards for wireless consumers, further increasing the need for network management.
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