4G market AdvancedTCA systems seek price/performance sweet spot

Minimizing latency is the name of the game.

John describes the design of a seventh-generation AdvancedTCA board targeting Telecom Equipment Manufacturers (TEMs), paying close attention to the role the availability of the single-socket L5518 Intel Xeon processor played.

When is a number not just a number? Here are two examples: call connection time and response time to new service requests. Telecom Service Providers are competing ever more intensely with the cable and satellite contingents for new customers. The race is on to add new consumer services without sacrificing the end user experience and Quality of Service (QoS) that are paramount to subscriber retention and growth. Latencies in the network affect how telecom consumers feel about service, so achieving a call connection time, for example, that is faster than before makes that time not merely a number but a vital part of the Service Providers’ competitive arsenal.

Crucial for minimizing these latencies are the AdvancedTCA SBCs charged with handling telecom control plane applications. If these blades were chefs, they would need to consistently dish up a broth that balances compute performance, overall cost, upgrade path, and thermal requirements. For SBC manufacturers, defining a price/performance optimized blade that meets Telecom Equipment Manufacturer and Service Provider requirements depends on these ingredients.

Telecom Equipment Manufacturers, also known as TEMs, want to use higher performing silicon at the system level. Such a deployment gives TEMs the strong foundation needed to support current 2G/3G applications while optimizing for the 4G market.

The RadiSys Promentum ATCA-4500 single board computer, based on the single-socket L5518 Intel Xeon processor, integrates a multichannel memory controller. Incorporating the controller boosts memory access bandwidths, and helps reduce substantially overall platform latencies compared to earlier CPU boards. The ATCA-4500 memory latency is more than 20 percent lower than previous generation (Intel 5408 processor-based) boards.

Real application benchmark

To better understand the telecom application performance of the ATCA-4500, RadiSys utilized a benchmark closely resembling the operation of many telecom control plane applications. This is a real application benchmark used by a top TEM. The benchmark simulates the control plane portion of a wireless network. It utilizes many threads sending and receiving a mix of message sizes. This is representative of the control plane traffic involved in the setup and tear down of a wireless network’s radio links. The benchmark is memory intensive and intentionally designed to mitigate the effects of large cache sizes and measure the true underlying performance of the compute subsystem. Memory transaction bandwidth for a typical telecom application is the resulting measurement.

The results are dramatic and telling. The total system message rate with the ATCA-4500 with a single-socket 60 W L5518 and eight virtual cores was higher than the dual socket quad core L5408 (Harpertown) board, and was double that of a dual-socket, dual-core LV Xeon (2 GHz) board.

Figure 1: Total System Message Rate with various AdvancedTCA CPU configurations.


Raising the bar on multicore/control, video, and packet processing for 4G

In the context of the wireless industry, the new 4G standards such as LTE and WiMAX have been set with very aggressive performance requirements. For example, the handover procedure within LTE is intended to minimize interruption time to less than that of circuit-switched handovers in 2G networks. Table 1 gives a snapshot of some of the LTE performance requirements:

Table 1: LTE performance requirements. Courtesy Motorola, Inc. LTE Technical Overview


Reducing control plane latency is a key performance target for 4G networks. Elements such as Mobility Management Entity (MME) provide control plane function for mobility and participate in the bearer activation/deactivation process, choosing the gateways for User Entities, and authenticating the user (by interacting with the HSS). MME can benefit significantly from a low-latency CPU subsystem such as the ATCA-4500.

Enabling pure performance for enhanced voice and video processing also benefits Service Providers competing in the 4G market. Such enhanced processing involves a few channels of high-definition encoding to many channels of medium-low definition encoding, greater use of encryption (high compute performance of the CPU plus option for look-aside or inline AMC), and adequate local storage for large code base and media storage (up to 32 GB onboard user flash). Delivering these types of leading performance features to a 4G network element are key to winning business with the Service Providers as they look to gain customers with new and performance leading applications.

Reducing migration cost by addressing both 2G/3G and 4G applications

The role of 2G/3G systems will remain significant as they form the solid ground on which the next-generation systems will be built. For now, they will continue to generate the main revenue stream for operators for several years in addition to forging the migration path to 4G. Figure 2 shows converged network architecture. Figure 3 shows high-level architecture for 3GPP LTE. 2G/3G systems such as MSC, RNC, SGSN, Call Servers, and Application Servers will also benefit from single board computers with functionality like that of the ATCA-4500 SBC. Subscriber density challenges can be addressed, given the ability to more than double the number of subscribers or transactions per AdvancedTCA slot for the same or even lower cost than previous generation boards.

Figure 2: Converged Network Architecture; Courtesy: Comsys Communication & Signal Processing Ltd

Enhances virtualization to aggregate legacy and new applications

Using virtualization capitalizes on the multicore environment, allowing bridging of the existing application into the new environment. Virtualization is best enhanced by large memory support – a key attribute of the ATCA-4500. This is significant for 2G/3G servers that are based on legacy applications.

Enables large in-memory database with up to 64 GB memory

The ATCA-4500 with 8 DIMM slots and memory capacity of up to 64 GB, fits applications such as HSS/AAA that support the migration to 4G. These applications require high local RAM storage as they maintain a large number of users in real-time.

Game, set, match: System-level thinking for the 4G market

Features TEMs should look for when planning to support a broad range of 4G and legacy network applications include:

n Higher bandwidth data (10G backplane bandwidth plus multiple GEs)

n Pure processing performance for enhanced voice and video processing applications

n Greater use of encryption (high compute performance, plus option for look-aside or inline AMC)

n Higher density of subscribers (large addressable memory with 8 DIMMs and flat addressing)

n Adequate local storage for large code base and media storage (audio, video, announcements)

n Use of virtualization to bridge existing applications into new environment, and also to offer more ways to take advantage of multicore processing environment – virtualization is most enhanced by large memory support for per-VM queuing and control

Choosing a single board computer capable of addressing a broad set of applications translates to significant savings in platform validation and training costs and fewer interoperability and support headaches. Working closely with a vendor such as RadiSys to obtain much higher performance over previous AdvancedTCA SBCs results in significant reductions in cost per subscriber or cost per unit, improving the bottom-line for both Telecom Service Providers and TEMs.

John Long is a product line manager at RadiSys, with a focus on AdvancedTCA Single Board Computers and storage. He has more than 10 years experience in the communication industry holding various marketing, sale,s and operational positions with Intel, Dialogi,c and AT&T. John has an MBA from Carnegie Mellon University.