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ATCA Plays Important Role in ASN Gateways for Mobile WiMAX


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February 06, 2008

ATCA Plays Important Role in ASN Gateways for Mobile WiMAX

By Mae Kowalke, TMCnet Contributor

Based on investments already made by companies in the telecom industry, everyone is expecting that mobile WiMAX will take off in a big way during the next few years. Yet, this technology is not yet fully proven, and as such many providers are now scrambling to get their service offerings up and running in time to keep up with what appears will be a very competitive market.

Key drivers for the mobile WiMAX market include VoIP, video, browsing/e-mail and backhaul.
Functions of the ASN Gateway (News - Alert)
One of the major elements in deploying WiMAX is the access services network (ASN) gateway. According to a recent RadiSys white paper (Mobile WiMAX (News - Alert) Gateways: Design & Implementation Considerations), the WiMAX Forum defines such gateways as being able to perform the following functions: Layer 2 connectivity for user devices, message transfer to the customer premises, discovery of available WiMAX networks and operators, relaying for Layer 3 device connectivity, and radio resource management.
Additionally, ASN gateways communicate with other nodes like AAA servers, home agents and DHCP servers.
That’s quite a lot to expect from the ASN gateway, and depending on the type of architecture or platform being used, different types of equipment is required to accomplish all these functions. AdvancedTCA (News - Alert) (ATCA) and AMC-based systems often play an important role in ASN gateways.
Types of ASN Gateway Deployments
Two examples of ASN gateway deployments illustrate how configurations and necessary equipment may vary.
In a service provider deployment, a variety of options exist for ASN gateways. Factors such as the number and density of base stations, and concentration of subscribers in a particular region must be considered. In urban areas particularly, picking a carrier-grade ASN gateway is necessary to support large numbers of simultaneous users.
In an enterprise deployment covering a limited geographical area, in lieu of using a base station, an ASN gateway can be deployed on one of the servers and controlling picocells/femtocells. This type of setup supports a limited number of users—several thousand at most. Some carriers are planning to soon offer hybrid cellular/WiMAX modems and handsets, enabling enterprises to jump on board with mobile WiMAX right away.
The nature of mobile WiMAX creates some unique design and implementation challenges for ASN gateways. One of these is that tasks such as data classification, packet forwarding and routing must be implemented on the hardware. Thus, the entire ASN gateway can only perform adequately if fast-path implementation is used.
ATCA’s Role in ASN Gateways
ATCA technology can help reduce time-to-market for mobile WiMAX by forming the foundation for ASN gateways. ATCA is an industry-standard, off-the-shelf technology that boasts flexibility and scalability needed to support long-term growth. It also offers predictability and enables providers to re-use components as demands change.
In essence, ATCA is a blade-and-shelf technology that can handle everything from protocols to cooling. It is ideal for multi-vendor environments such as mobile WiMAX deployments.
Outside of mobile WiMAX, ATCA has already proven itself as a technology that can deliver carrier-class reliability. Using ATCA, an established technology, takes some of the uncertainty out of mobile WiMAX deployments.
Characteristics of the Ideal ASN Gateway
To prevent having the ASN gateway be the weakest link in the quality of service chain, providers should keep in mind the following guidelines, RadiSys (News - Alert) said in its white paper. These represent the ideal characteristics of an ASN gateway.
  • Easy to install and manage
  • Proven compliance
  • Support for NWG ASN gateway reference points via a standard GigE interface
  • Fast path integration for GRE and IP-over-IP tunneling using R6/R3 interfaces
  • Optimally priced for staged roll-out, scalable from hundreds to thousands of sites
  • Support for optimal rate of users
  • Throughput of up to 1 Gbps per blade
  • Support for security using IPSec accelerators for encryption
  • Predictable, fast handovers (less than 50 ms)
  • IPv4 routing
To learn about how RadiSys’ ATCA solutions meet the criteria outlined above, please visit the ATCA channel on
Mae Kowalke is an associate editor for TMCnet, covering VoIP, CRM, call center and wireless technologies. To read more of Mae’s articles, please visit her columnist page. She also blogs for TMCnet here.

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