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By Keith Cobler, Tektronix
Introduction
Fixed-Mobile Convergence (FMC) is gaining considerable attention with wireless and fixed network operators, as well as mobile device and network equipment manufacturers. For many operators, FMC appears to be the quickest way to rollout new applications and services that combine the advantages of wireless with the advantages of fixed networks. For others, FMC is merely a stepping-stone towards full network convergence using technologies such as IMS (IP Multimedia Systems). But for most, the major application for FMC is voice convergence – namely the ability to seamlessly roam on a cell phone or handheld between WiFi and cellular networks.
Convergence
Convergence is occurring at many different levels within the communications industry. At the device level, new dual-mode handsets and devices are just now coming to market; e.g., WiFi/GSM, WiFi/CDMA, WiFi/W-CDMA and UMA handsets. At the network level, network operators continue to migrate their networks towards all-IP infrastructures that will eventually support triple-play services. And at the service level, new applications and services that leverage IP packetized video, voice and data for richer, more personalized services and applications, are underway or near deployment.
For those service providers that can capitalize on convergence and deliver the new personalized services, they will be positioned well in a highly competitive market. The downside, or risk is that consumers have come to expect a high quality of service independent of how they accessed the network. So for the customer who traditionally accessed their applications via DSL or cable modem, they will now expect that they can have the same quality of service if they were to access their application over wireless – like 3G or WiFi.
The bottom line is “how will service providers and network operators ensure that the quality of service they offer is adequate” – especially given the fact that multiple networks may be involved. For many, the answer to this question is critical – especially considering what's at risk when you lose a paying customer to the competition. A false start in FMC will delay substantial adoption and revenue growth.
Fixed-Mobile Convergence: New Challenges for Network Operators
FMC introduces yet another new definition of what “end-to-end” means for services. With FMC, part of the issue is that the definition of end-to-end depends on which networks are involved in delivering a particular service. If, for example, the customer is accessing the service from a WiFi or cellular network, the operator will need to monitor and trouble-shoot at least three networks at any given instant in time – where each network may be a different technology; e.g., WiFi, IP broadband access/core, or mobile. To add to the complexity, each of these network technologies is constantly in flux, undergoing constant change in an effort to keep up with customer and market demands. Some examples of this are the multiple WLAN standards, or the current state of a cellular network (UMTS release 4, 5 or 6, etc.).
Operators offering FMC services have to support a converged network environment, which physically translates to:
FMC also introduces a new session model for a FMC service, which not only has more messages per call but also more variations of signaling flows, depending on the network. If more traffic is introduced as a result of these new service offerings, network operators may be forced to re-optimize the underlying networks involved in the delivery of these services. And finally, there are the issues related to roaming and automatic handovers between WiFi and cellular that will have a significant impact on the quality of experience for the end-user. Undoubtedly, all of this complexity must be managed by the network operators to ensure that the end-user's experience is of high quality – and if not, problems must be quickly recognized and resolved.
Taking a look at the physical networks involved in an FMC service, operators will be required to manage and trouble-shoot multiple access technologies. For example, an operator offering a FMC service to its enterprise customers may use WLAN over a DSL broadband IP connection while a consumer subscriber may be using FMC services through a mobile access network such as GERAN or UTRAN. For each access method available, different network elements will be utilized. To ensure the seamless operations of FMC services for the end-user, the network operator must have end-to-end visibility of the service and be able to manage all of the network elements involved.
FMC is more than making sure the connection is established and maintained – it's about offering more multi-media IP based services. As more network operators migrate towards offering IMS based applications for FMC customers (like gaming, instant messaging, streaming video, etc…), the ability to manage the migration to IP becomes critical in maintaining a high customer quality of experience. Some of the IP-related issues network operators are faced with are: interoperability between IP and legacy networks, QoS visibility and management, authentication/billing, security and network capacity planning. While FMC requires operators to have a good strategy for managing the access networks, the complexities in migrating to an IP core network cannot be ignored.
In addition to network and technology considerations, network operators have to deal with the impact that convergence brings about in internal organization support structures and business processes. Network Operators must be able to quickly characterize a problem so that resolution can be assigned to the appropriate technical group for resolutions. FMS will also impart customer care, billing and sales and marketing groups.
Test, Measurement & Monitoring Solutions
As with most major new technology initiatives, the challenge begins with the network equipment manufacturers. For equipment manufacturers, the major points of concern are: Do the network elements perform according to specifications, Do they perform accordingly under loaded real-world network conditions, and Does the equipment interoperate with other equipment. Many are looking towards TISPAN to provide guidance and standardization for converged services and the associated protocols that come along with it. The concept of TISPAN centers around subsystems cooperating with one another and the sharing of common components. Whether TISPAN is ready or not, equipment manufacturers designing FMC equipment will need to rely on equipment such as the Tektronix Spectra2 for converged, multi-protocol analysis to address these needs.
From a
service assurance perspective, today's advanced network monitoring
systems combine the benefits of both passive and active monitoring. Passive
network monitoring systems reside within the network and perform
non-intrusive diagnostics of the network. With correct planning
and probe layout, network operators have the ability to drill-down
and isolate the individual network element that may be impacting
end-to-end service quality. An example of this type of system is
the Tektronix GeoProbe/Unified Assurance solution that gives network operators end-to-end
visibility into service delivery performance in real time. In the
example below, the quality of a voice call is measured using a high-level Key Performance Indicator (KPI),
which is based on a MOS score. When the quality of the call decreased
below it's minimum threshold, the operator was immediately notified.
From here, the operator can then drill-down to the specific network
elements and signaling involved to troubleshoot
and resolve the situation.
In an active test system, end-to-end test calls are introduced into the network and analyzed, as opposed to monitoring actual traffic (as with passive monitoring systems). With active test, network operators can isolate and troubleshoot individual links that may be suspect because active test calls have known reference media contents, deep comparative analysis at both the analog and packet layers, leading to quick root cause determination and problem resolution. In addition, self-diagnostic tests calls can be initiated to test end-to-end service quality directly to the FMC handheld device.
By combining passive and active monitoring techniques, network operators are in a better position to not only maintain the end-to-end quality of service, but also be proactive in managing and allocating their network resources. In the case of fixed-mobile convergence, operators will need to anticipate what will happen at the network and service level and how these results will impact the end-user's quality of experience.
Conclusion
Given the challenges that network and service operators will face to deploy fixed-mobile convergence successfully, there are a few key points to keep in mind:
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