Case Study | RadioFrame Networks Node B

Introduction

Combining its industry-leading Trillium software and Trillium Professional Services in another highly successful customer engagement, Continuous Computing provided a powerful 3G network solution for RadioFrame Networks, a leading supplier of targeted base-transceiver station (BTS) solutions to the wireless communication industry.

With RadioFrame's unique requirements squarely in mind, Continuous Computing developed fully-integrated Node B system software for a high-speed downlink packet access (HSDPA) enabled 3G Node B picocell base station.

HSDPA facilitates increased data rates required to support Next Generation Network applications such as mobile TV, streaming music, and presence-enabled multimedia messaging.

Continuous Computing's wireless protocol expertise and Trillium Professional Services capability enabled RadioFrame to manage costs and meet time-to-market requirements with its latest 3G product offering.

Business Challenges, Technology Solutions

Nearly two-thirds of wireless voice and data usage happens indoors, according to an August 2005 survey by Strategy Analytics. However, coverage is often an issue in indoor locations because signals do not travel well through concrete, steel, and other building materials. Dropped calls and slow connections annoy business users working in offices. Remedial actions such as giving service credits and adding customer service staff drive up the operator's costs. As the importance of wireless connectivity grows, business users increasingly demand a robust indoor connection.

Indoor coverage at home is also important in view of the accelerating trend toward wireline displacement. In October 2005, 17 percent of consumers who signed up for wireless service over the previous 90 days said that they had stopped using their landline phone, according to a survey by the Consumer Electronics Association. In-Stat predicts that by 2009 between 23 percent and 37 percent of U.S. consumers will have switched, conservatively estimated at 30 million wireless-only users.

With the growing selection of handsets and PC card modems that combine 3G and 802.11, wireless-only users can readily switch to Wi-Fi when cellular network coverage is not available. Cellular operators, who do not want to lose revenue to public Wi-Fi hot spots, need to be able to guarantee a strong signal where cellular subscribers spend most of their time - in their homes and offices. By plugging coverage holes and by boosting voice capacity and data throughput in indoor environments, picocells ensure that users can complete calls and get a data connection, making them more likely to choose cellular rather than alternatives such as Wi-Fi.

A picocell is an all-in-one, single-board transceiver housed in a small case, connecting to a DSL or cable modem box, and integrating with the mobile operator's network. Picocells provide a convenient, cost-effective way for mobile operators to fill coverage gaps which may emerge when an operator begins phasing out analog in favor of CDMA or GSM technology. Picocells can also help operators hit coverage targets under the terms of their 3G licenses because a mix of base stations and picocells can be a faster and more cost-effective way to expand coverage than a build-out that relies entirely on large base stations.

Customer Collaboration

With two dedicated engineering teams, one in Bangalore and one in San Diego, Continuous Computing skillfully carried out an aggressive Node B project in accordance with RadioFrame Networks' internal Design Control Process (DCP). The DCP is based on a modified, waterfall product development cycle and covers requirements management, project planning, project tracking, peer reviews, and software configuration management. As required by the DCP, Continuous Computing maintained a Node B project spreadsheet tracking progress and identifying action items. Roadblocks or issues that surfaced during development were promptly addressed so that work could proceed as planned without the need for change orders. Operating at the highest level of professionalism, Continuous Computing executed the Node B project on time and on budget.

Continuous Computing provided a cost-effective solution to RadioFrame at a critical time in its product development cycle. With only one software engineer on staff, RadioFrame would have had to spend a significant amount of time and resources on recruiting candidates to do the Node B work. However, by relying on Continuous Computing's Trillium Professional Services team, RadioFrame saved at least eight man-months in development time and was extremely satisfied with the results.

Success with Continuous Computing

Poised to build on its previous success with GSM and GPRS BTS products, RadioFrame retained Continuous Computing in 2005 to develop the system architecture and requirements for Release 5-based FDD-compliant Universal Mobile Telecommunications Systems (UMTS) Node B base stations, as defined by 3GPP standards. Figure 1 shows the placement of the Node B base station within the UMTS network.

This 3G network architecture supports the standard 3GPP Node B with one or more cells within the UMTS Terrestrial Radio Access Network (UTRAN). Figure 2 shows the network architecture of the Node B base station.

The Node B had to support the following functions:

• Iub Transport resources management
• Iub Link management
• Radio Resource management
• Cell Configuration management
• Implementation-specific Operation and Maintenance ("O&M") transport
• System Information management
• Traffic management on common, dedicated, and shared channels
• Timing and synchronization including node and channel synchronization

In a preliminary Quick!StartŸ engagement within the Trillium Professional Services program, Continuous Computing outlined the complete system architecture in a comprehensive document identifying and describing the interaction of all Node B system components, including RadioFrame-specific modules. As designed, the RadioFrame modules would interface directly with Continuous Computing's modules to transfer information between the physical layer and other RadioFrame components on the Radio Frame Unit platform. RadioFrame was particularly impressed with the way in which the layers were put together on the board and how they were tied to existing Trillium protocol stacks. Continuous Computing's well-designed Trillium software was fully integrated with the existing RadioFrame platform while allowing capacity for future extensions.

Pleased with the innovative and scalable design, RadioFrame asked Continuous Computing to develop a full-blown technical proposal for the Node B project. The deliverables, schedule, and cost all met RadioFrame's requirements, and work proceeded in three phases: Broadcast Channel Integration, Voice and Data Call Support, and HSDPA Integration.

Over the course of the eight-month project, Continuous Computing developed, tested, and delivered the complete Node B software and documentation except for the physical layer. Specifically, the Trillium Professional Services team created the Node B control application, providing the following features:

• Application State Machine for NBAP signaling between RNC and Node B over lub interface
• Implementation of logical O&M function
• Interfacing with RFN platform Base band controller to set up initial Node B configuration
• Complete resource management for Bearer Channels
• Interface with System Initialization and management entity for stack initialization
• Interface with RFN O&M Stack manager entity for configuration, control, and statistics

As part of the data plane application, Continuous Computing provided complete MAC-HS functionality to support HSDPA in Node B. Facilitating data rates of 2Mbps, the MAC-HS transmits data on HS-DSCH as well as managing the physical resources allocated to HSDPA. This module transmits the downlink ("DL") HS data received from the data relay function to the physical layer, and interfaces with the Network Time Protocol-based timing module to receive interrupts for DL data scheduling. Project testing was performed using an integrated test stack functioning as a test generator of lub Interface.