Building Telecom Network Elements on an AdvancedTCA Common Platform

Telecommunication Market Challenges

The convergence of data and communication networks and the deployment of next-generation wireless networks are currently gaining momentum, while bandwidth requirements for IP services are steadily increasing. This poses a challenge to telecom equipment manufacturers (TEMs) and network equipment providers (NEPs) to provide new types of equipment at ever increasing densities and at lower cost. In an increasingly competitive environment, both network operators and TEMs/NEPs are focused on the specific factors that differentiate their own products, making outsourcing an increasingly attractive way to obtain this new equipment within available budgets and timescales.

Benefits of a common platform approach

The idea of using a single platform technology to build multiple product lines has been identified as a valuable tool in an increasingly competitive market. This common platform approach offers significant advantages over customized in-house development:

  • Simplifies logistics - A common platform based on a single, versatile, platform technology reuses the same types of hardware and software building blocks. This provides logistical benefits to TEMs and network operators.
  • Reduces time-to-market - Outsourcing a pre-integrated platform significantly reduces product development time and accelerates the introduction of new services.
  • Increases return on investment - A significant amount of of development can be spun-off from one application to another, providing increased return from technology investments.
  • Frees resources - Outsourcing at the platform level allows engineering resources to focus on value-added developments and simplifies the supply chain.

AdvancedTCA Standard

AdvancedTCA® is an industry standard for next-generation telecom computing platforms. It was developed by a cross section of industry suppliers and users, under the umbrella of the PCI Industrial Computer Manufacturers Group (PICMG®), to meet the unique requirements of the telecom industry.

AdvancedTCA is primarily a packet-based, switched blade architecture that defines a fully redundant system, including shelf management and remote access to each system component via IPMI. The data transport technology utilitzes 2N-redundant switches, such as the dual star base interface, the dual star fabric interface, or other fabric options for future use. The node boards or blades are 8U in height, with 14 slots able to fit in a 19-inch rack. Node boards are hot swappable, with the open standard securing interoperability of boards and systems across different vendors. Power input is -48 VDC adapted to the typice central office environment. It is the goal of the AdvancedTCA standard to support the migration towards converged networks by offering a high availability modular computing architecture. Advantages quoted for the AdvancedTCA architecture include technology headroom, engineering reuse, volume economics, component interoperability, and application flexibility.

Key Application Areas

At least two major application areas can be identified for a common-platform approach. One is server-centric and is mainly targeted towards control and management plane applications. The other is oriented towards data plane usage. A common platform should therefore combine the shared characteristics that support both applications and ultimately even support a mix-and-match combination for multi-service applications.

Applying the AdvancedTCA Common Platform

Both server and data plane applications operate in the central office environment. An AdvancedTCA platform can deliver the 5NINES availability that these applications require and host a variety of general purpose processing, network processing, media processing and line interface blades interconnected by a redundant backplane networking infrastructure.

Other industry standards used in the common platform are the Service Availability Forum’s interface specifications for high availability middleware and the Open Source Development Lab’s Carrier Grade Linux for blade operating systems.

Typical server-type telecommunciation applications that can be built on an AdvancedTCA base platform are:

  • Softswitch: A Softswitch represents the call-control part of a converged network out of Media Gateways and Media Gateway Controllers, and as such is tied mainly to signaling communication protocols such as H.323, SIP, Megaco, SIGTRAN, or SS#7. The core component of the Softswitch’s software architecture will be hosted on general-purpose processor blades. By interfacing to the HA manager, this software can also be made highly available. In a pure IP environment, the AdvancedTCA base and fabric interface networking may directly connect the system into the WAN, while with OC-x connections, specialized line interface cards are incorporated into the system.
  • Home and Visitor Location Register: A Home Location Register (HLR) and Visitor Location Register (VLR) represent geographically distributed subscriber databases for indentification and authentication of roaming mobile users in wireless networks. Communication towards HLR and VLR is of the signaling type and requires similar blades to softswitches. For larger scale data storage, i.e. beyond the 300GB mark, these systems typically feature access to a central, redundant storage subsystem. AdvancedTCA offers Fibre Channel (FC) technology over the backplane and FC-capable processor blades can use this to interface to FC storage modules, also hosted inside the AdvancedTCA system’s blade slots.
  • Media Server: Used mainly for audio and video content retrieval, these systems typically forward their payload in IP packet form to appropriate Media Gateways. The main requirement, after media-oriented processing power, is a sufficient media repository. A media server implementation can host FC-based storage controller blades as well as FC storage blades.

Data plane applications differ significantly. AdvancedTCA platform focus areas lie in the wireless networks’ access and mobile core domain (RNC, SGSN, GGSN, Media Gateway), as well as in the wireline access domain (DSLAM, BRAS, Router). AdvancedTCA technology meets the need for physically separated control and data plane communication paths in these applications by providing a fabric interface as a second, dedicated high-speed network with flexible topologies. The resulting application architectures are:

  • Radio Network Controller (RNC): The RNC represents the interface between the UMTS Radio Access Network and the circuit-switching and packet UMTS Core Network. The resulting interfaces include multiple DS-1 links or channelized OC-3 interfaces for NodeB communication, OC-3 to OC-12 interfaces to both the 3GMSC for voice traffic, and SGSN for packet traffic. On the data plane the RNC concentrates access through a large number of communication protocols. Next to the dedicated system hardware for the additional fabric interface are line interface cards of different types and network processors (NPU) used for protocol processing.
  • Signaling GPRS Support Node (SGSN): An SGSN provides routing of wireless packet data into an operator’s IP network from a number of RNCs. Next to the RNC-opposing interfaces of OC-x type, the SGSN needs to support signaling interfaces (e.g. SS#7 on DS-1) and IP data traffic which typically uses Gigabit Ethernet. For the latter, the AdvancedTCA platform’s Ethernet-based backplane communication (base interface is Ethernet by default) is ideal and can be forwarded directly from the AdvancedTCA switch uplinks, provided the operator’s IP environment can be accomodated through network address translation.
  • Media Gateway: Being the data plane counterpart to a Softswitch, a Media Gateway provides the capability to transcode TDM voice circuits into voice-over-packet protocols such as VoIP. As it is controlled from a Media Gateway Controller, which may be located outside of the MGW’s system premises, it is a pure data plane architecture and interfaces to both the packet and circuit-switched worlds with line interface cards and the switch uplinks. DSP processing resources on dedicated or line-card blades are responsible for encoding and decoding of payload data.
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