This section looks at the technology building blocks required for developing broadband solutions. The challenge of the semiconductor manufacturer is to design silicon and software with a complete solution focus and not just chips or chipsets. As shown in Figure 4, customers have many needs that require a multitude of core competencies for semiconductor manufacturers to satisfy. First of all, customers desire flexible solutions that can accommodate a range of densities to meet requirements scaling from endpoint devices to CPE to carrier-class equipment. Flexibility dictates the need for programmable architecture that can facilitate quick and easy software upgrades to address new features, interoperability issues, performance, and evolving standards.

Figure 4

For broadband technologies, high-performance digital signal processors (DSPs) are required to implement the various signal-processing algorithms necessary to perform functions such as modulation, voice compression, and video processing. The industry has moved beyond general-purpose DSPs to specialized silicon/software solutions optimized for a particular vertical application. These solutions include the following:

• DSP cores
• RISC processor cores
• Networking interfaces, including Ethernet, Utopia, PCI, USB, 1394, etc.
• Software with well-defined application programming interfaces (APIs), including signal-processing algorithms, protocol stacks, device drivers, real-time operating system pre-ports, network management, and application software
• High-performance analog components, including data converter and amplifiers
• Power management solutions, including power supply control and battery management
• Digital modem technologies for broadband communications
• Radio frequency (RF) wireless technologies for wireless devices
• Voice over packet (VoP) technologies, including voice compression, echo cancellation, tone processing, dial modem, Group 3 facsimile, and telephony signaling
• Networking technologies, including routing, switching, filtering, encryption ,and quality of service (QoS)

These solutions must be very low power to allow battery- or line-powered operation for endpoint devices or to scale in an infrastructure environment where equipment is limited by power consumption and heat dissipation.

Cost is always a concern. Customers want semiconductor providers to provide them with the lowest-cost solution, and this is for the entire customer's solution, not just the semiconductor manufacturer's portion. Thus, the semiconductor manufacturer must understand the total build of materials (BOM) cost of the equipment and work at reducing the total BOM. This includes integrating more functionality into the silicon solution and eliminating the need for "glue" logic. It also includes reducing manufacturing costs by making the solution easy to build by minimizing the number of printed-circuit board layers, making the chip package easy to mount and signals easy to route on the printed-circuit board. There is a constant need for cost reduction for mass-market deployment.

Customers want to know that the semiconductor's roadmap will offer significant cost reduction for subsequent customer refreshes of the product. The key to facilitating continued cost reduction is to have high-volume manufacturing facilities with leading-edge process technologies coupled with strong system-integration capabilities.

To speed customer time to market, semiconductor manufacturers must offer the customers hardware reference platforms that are integrated with software, fully system tested for conformance to industry standards, interoperable with other vendors, and product hardened under real-world conditions.

The following subsections look at how building blocks are put together to deliver broadband solutions for infrastructure equipment, premises access gateway equipment, and broadband endpoint devices.

Infrastructure Equipment
As shown in Figure 5, broadband infrastructure gateway equipment is responsible for interconnecting broadband access services to the optical core network infrastructure. For multiservices gateways, multicore DSP platforms facilitate the ability to support multiple broadband access technologies as well as traditional voice-grade services. Communications processors containing high-speed processing engines and networking interfaces perform protocol processing and network-management functions. High-speed aggregation logic is required for performing packet processing while providing QoS functions.

Figure 5

Infrastructure gateway equipment providing broadband access is driven by the need to support a large number of end-user connections in a concentrated area (CO or RT unit in the neighborhood) while being constrained on the total power (heat) dissipation.

The concept of solution density has been developed to help service providers and OEMs more clearly understand the technical requirements for implementing high-density products. From a system-engineering perspective, a solution must be evaluated on how the combination of system elements delivers a complete solution with the lowest power and smallest area without compromising quality and features. Solution density refers to the optimization of the overall system architecture, taking into account the following critical elements:

• Power of the solution expressed in milliwatts (mW) per end-user channel
• Density of the solution expressed in end-user channels per square inch
• Cost of the solution, including silicon, hardware, software, and any intellectual property license fees
• System partitioning, including packet aggregation and routing
• Software features that define the functionality of the product
• Network-management capabilities to address high availability and accountability

To engineer an optimal solution, cost, power, and area must be evaluated on a total system basis and must be a function of the features and capabilities supported. For example, the designer must consider the need for external logic, e.g., external memory, aggregation logic, layout/routing issues, etc. In many systems, power (heat dissipation) is the key driving facto,r especially for high-density solutions. That is, most solutions run out of power in the rack before they run out of board area. Proper functional partitioning is also essential to avoid processing and/or bandwidth bottlenecks in the overall system when scaling to support very large numbers of end-user ports.

Premises Access Gateway Equipment
As shown in Figure 6, premises access gateway equipment is responsible for terminating a broadband access pipe from a service provider and making that pipe available to the home or home-office network. Communications processors containing high-speed processing engines and networking interfaces perform protocol processing such as bridging, routing, packet filtering, and firewall operation. Typically, a premises access gateway provides connection to a single broadband access medium-e.g., cable, DSL, or fixed broadband wireless-but may support multiple LAN interfaces such as wired Ethernet, wireless Ethernet, and Bluetooth. VoP technologies are required for derived voice services.

Figure 6

Broadband Endpoints
As shown in Figure 7, broadband endpoint devices come in many forms, such as PDAs, digital cameras, MP3 players, digital television, and IP phones. DSPs perform multimedia processing such as MP3 audio, MPEG-4, and JPEG imaging. High-quality analog components are essential for performing analog- to-digital (A/D) and digital-to- analog (A/D) processing. These consumer devices must be extremely low cost. Devices that are portable handheld devices must be very low power to ensure long battery life. Also, devices that are line powered, e.g., from the infrastructure, Ethernet, or universal serial bus (USB) interface, must adhere to the power constraints of that interface. Thus, low-power devices coupled with power-management technologies are essential.

Figure 7