Technology
OFDMA® Overview
Since Runcom introduced its proprietary Orthogonal Frequency Division Multiple Access (OFDMA®) technology to the world in 2000, it has been enthusiastically embraced as the next generation international standard by the prestigious governing boards that are defining the direction of the wireless arena, including: the Digital Video Broadcasting (DVB) committee, ETSI-BRAN and IEEE 802.16a/d/e. Consequently, OFDMA® now provides the basic infrastructure for the DVB-RCT/ETSI broadcasting standard and is the preferred technology driving the BWA market. Moreover, it is considered to be the leading technology for the upcoming 4G cellular infrastructure.
The Wireless Challenge: Overcoming Solid Obstructions in the Air
For all its inherent advantages, wireless technology has its own hurdles to overcome. Unexpected obstructions in a signal path, such as buildings or airplanes, may cause transmitted signals to rebound off of these surfaces, subsequently causing part of the signal to take a shorter path, while another part continues along a longer path. This multi-path effect can cause interference on the receiver side and cause considerable loss of data.
The existing OFDM® (Orthogonal Frequency Division Multiplexing) technology in widespread use in many wireless markets sub-divides a single, high-speed data signal into multiple (tens or hundreds) lower speed signals for parallel transmissions, creating a system with increased tolerance to noise and multi-path, while simultaneously enabling more efficient use of bandwidth allocation. Noise elimination and multi-path immunity allow for wide-area, multi-point coverage. Moreover, the more efficient use of bandwidth enables a multiplicity of high-speed channels over a single frequency band.
OFDMA® (Orthogonal Frequency Division Multiple Access) is Runcom’s unique enhancement to existing OFDM technology. OFDMA® divides a signal into sub-channels (i.e. groups of carriers), with each sub-channel being allocated to a different subscriber. Different sub-channels can then be combined from various carriers. Each subscriber can be treated separately independent of location, distance from the base station, interference and power requirements. Various modulations can be used for each of the carriers in the system to provide improved coverage and throughput. Sub-channel structure of the OFDMA® enhancement enables more efficient duplexing techniques, such as FDD (Frequency Division Duplexing) and TDD (Time Division Duplexing), creating a signal that is immune to interference and capable of high data throughput. Moreover, the technology improves power gain per channel, resulting in better coverage and range availability, larger cell radius, smaller power amplifiers and antennas and subsequently, lower investment in capital equipment.
The "Holy Grail" of OFDMA® : Merging Broadband with Mobility
Since the early days of commercial wireless communication, service providers and broadcasters have been awaiting the arrival of a technology that can leverage the inherent flexibility of mobile devices for a wide variety of enhanced communications services. OFDMA® provides for this vital market need. The Power Concentration ability in the upstream link together with the downstream power boosting capability and combined with the technology's inherent adaptive modulation and error correction techniques, assure a solid and "installation free" solution for the fixed and mobile wireless markets. Furthermore, Runcom's OFDMA®-based products are compatible with "smart antenna" technologies, such as spatial diversity, space-time coding, beam forming, etc., that can enhance the signal penetration even in the toughest environments. In this manner, OFDMA®, as integrated into the new IEEE 802.16e standard for mobile wireless MAN, infuses standard mobile devices with seamless communications abilities. Cellular phones and PDAs can now be converted into multi-faceted communication centers, providing such services as broadband Internet, email, Video on Demand, Interactive games, VoIP, distance learning and e-commerce.
OFDMA® in the DVB-RCT (Digital Video Broadcast- Return Channel
Terrestrial) Environment
Superior to existing solutions based on single-carrier technologies that currently are employed in the xDSL and CATV markets, OFDMA® enables total, bi-directional broadcast and broadband telecommunication convergence that operates over terrestrial infrastructure. Designed for fixed, nomadic and mobile applications, OFDMA® products provide faster and more effective wireless data transmission for Digital Interactive TV providers and are easily deployed in base stations. Subscribers will be totally transparent to the technology as they can simply plug in their OFDMA®-enabled set-top box straight out of the package and begin enjoying the myriad benefits it provides including Interactive TV, video broadcasting, video conferencing, Video-On-Demand (VOD), Turbo Internet and telephony. It is the first technology to successfully address the challenge of seamless communication between digital broadcasters and their subscriber base and fosters true interactivity.
OFDMA® in the BWA (Broadband Wireless Access) Environment
OFDMA® enables carriers to traverse the last-mile bottleneck and provide subscribers with enhanced broadband services. The optimized use of bandwidth for the simultaneous, bi-directional and high-speed flow of data for multiple subscribers is allocated according to customer requirements. A dedicated base station is linked to carrier / ISP infrastructure to receive a subscriber's application and data transfers, providing PMP (Point-to-Multi-Point) connectivity. OFDMA® facilitates optimal use of bandwidth over the given frequencies without collision between channels. It overcomes interference and provides maximum Bandwidth on Demand (BOD) by using logical sub-channels that support scalability, multiple access and an advanced array of processing capabilities.
