Marvell Technology Group (MRVL)

Satisfying Bandwidth Demand

        Businesses and consumers today are creating rapidly growing demand for broadband access to large volumes of information in multiple forms, including voice, video and data. This demand is driven by the introduction of new data-intensive computing, communications and highly integrated consumer electronics applications, such as web-based commerce, streaming audio and video, and voice over Internet technology. In addition, information is increasingly available via networks through a variety of access devices, including personal computers, digital cable set-top boxes, handheld computing devices known as personal digital assistants, and wireless phones. These applications and devices require increasingly higher data transfer rates within computing systems and the data storage devices that support them and across the network communication infrastructures that serve them.

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        Achieving high integrity data recovery and transmission becomes increasingly difficult at higher data transfer rates. Data transfer rates, often referred to as bandwidth, are measured in terms of bits per second transmitted over a given medium. In addition, computing and communications systems must transfer data reliably at very high speeds using a wide range of physical transmission media, including magnetic and optical storage disks, twisted pair copper wire, coaxial cable, fiber-optic cable and open air.

        A critical element of these systems is a physical layer device, which performs the important interface functions between the computing and communications systems and the storage or transmission media. In computing systems and in emerging consumer electronic devices, data is stored on a hard disk drive in analog form, but these analog signals must be converted to digital signals for use within these systems. Similarly, in communications systems, data is typically transferred over the transmission medium using analog signals; however, within the communications systems, data is processed digitally. The physical layer device provides the critical interface between the analog signals stored on magnetic disk drives and transmitted across physical media and the digital data that computers and communications systems can understand and manipulate. Physical layer devices often determine the overall performance of the system. In order to achieve high integrity in data transmission and recovery at high transfer rates, physical layer devices must overcome a number of factors that can impair signal quality and introduce errors, including substandard media, noise, signal level degradation over distance, adjacent line and multi-path interference and signal echo. In many computing systems and communication networks, bandwidth bottlenecks arise where the media and physical layer devices are incapable of supporting the required data transfer rates. As transmission speeds approach the fundamental limits of a particular transmission media, physical layer devices must increasingly employ sophisticated signal processing algorithms and techniques to accurately recover the transmitted data.

        When the data is transmitted wirelessly through the open air, an added level of complex signal processing algorithms and techniques are required to maximize interference immunity, performance range and to enable a high level of data security. Additionally, the wireless solutions need to employ sophisticated radio frequency, or RF, technologies utilizing radio communications. Because most wireless applications are utilized by mobile devices, low power consumption and small size are also critical requirements for such devices.

        To meet the demands of increasingly higher data transfer rates within computing systems and across communications networks, the data must be more reliably and intelligently transmitted across the systems. This has resulted in a transition from repeater to switch connections. Switches route data through the communications system with bandwidth dedicated to each end-user and have the potential to intelligently manage the data transmission. Additionally, there is an increased demand on today's switches as previously separate voice communications systems, video communications systems and data communications systems are converged into single systems that handle voice, video and data seamlessly.

        Also, as the rate and variety of data transmission increases, the communications systems that support such transmissions must handle more data and employ more sophisticated functions. This puts an increasing strain on the host central processing unit, or CPU, within the system and, as a result, makes the subsystems that support the CPU more critical. The system controller supports the CPU by managing the movement of data to the various data processing functions to free up the host CPU so that it can concentrate its resources on other more processor intensive functions while the data movement is taking place.