Digital Microwave Radio Transceivers

Digital Microwave Radio Transceivers

Alcatel Telecom Radio,
Space & Defense Division
Nanterre, France

Wireless transmission links are used in a wide range of networks, from fixed and mobile public telephone networks to corporate and other private networks. Wireless links enable operators to build their networks quickly, taking much less time to install than cable. In addition, system operators can avoid long, drawn-out negotiations over cable rights of way.

Cellular operators also appreciate the fact that they can build the network gradually according to where and when the subscriber traffic increases. Because of the fast, easy installation and flexibility of microwave radio links, mobile operators increasingly favor low and medium capacity links for interconnecting base stations. Generally, these links are used in short-haul configurations although longer distances may be involved along highways or coastlines.

An advanced new generation of digital microwave radio transceivers for low and medium capacity applications has been introduced. The 9400UX and 9400LX series microwave radio links offer network operators substantial savings in ongoing operating and maintenance costs. The new family also features distinctive advantages in terms of the breadth of the product range, flexibility, physical size, cost effectiveness, networking and ability to evolve over time.

The radios are designed for use in mobile or fixed, public or private, and established or emerging networks. These new transceivers offer 10 transmission rates and, once the series is complete, will be available in 14 microwave frequency bands from 1.5 to 60 GHz. Seven short-distance transceivers covering 13, 15, 18, 23, 25, 28 and 38 GHz and three long-distance products covering 2, 7 and 8 GHz are in production currently.

Short-haul Radios

The 9400UX series short-haul low/medium capacity digital radio systems comply with the International Telecommunication Union and European Telecommunication Standard Institute (ETSI) standards. The radios are particularly suited for roll out communications networks in urban and suburban zones. The transceivers feature embedded multiplexing and transmission functions for 2 x 2, 4 x 2, 8 x 2, 16 x 2, 8, 2 x 8, 3 x 8 + 4 x 2, 4 x 8 and 34 Mbps capacities, and good spectrum efficiency using four quadrature amplitude modulation with digital filtering. The modem features forward error correction and adaptive equalization. The digital frame incorporates a link identity code to prevent unwanted signals. Frequency-agile RF front ends provide coverage over a complete frequency band with only four different outdoor units. Different software packages make the system capacity agile up to a maximum (defined as an option) of 16 x 2 Mbps with the same unit. Systems above 23 GHz incorporate static power control.

The systems feature near- and remote-end loopback facilities as well as an embedded tributary cross-connect matrix for test or network reconfiguration purposes. Automatic errorless receiver switching is used on -1 + 1 configurations to protect the most critical transmission paths. The system incorporates built-in test functions such as a pseudorandom bit sequence generator to insert a standard test signal for bit error rate measurements.

The 9400UX system consists of an outdoor unit (ODU) and an indoor unit (IDU). The ODU is designed for operation in harsh climates and can be fitted with an integrated antenna (up to 600 mm in diameter). The unit features a compact, lightweight design. Pole mounting permits easy installation on masts or walls and provides accurate antenna alignment. A service kit establishes the receive signal level and a connection to the link's service channel. The 9400UX system also uses a standard coaxial cable between the two main units to transport the traffic, remote supply voltage and auxiliary information over long runs.

The IDU's compact, reversible design enables the same unit to provide front or back access connections. The unit installs in a standard 19-inch or ETSI rack, or in tight cellular base station spots.

The unit's software package determines maximum system capacity, defining the capacity agility range. ODUs can house an integrated RF loop antenna, allowing stand-alone terminal tests. The 15 and 18 GHz systems offer high transmit power options for longer hops and improved transmission. The 9400UX systems can incorporate as many as five 64 kbps auxiliary channels with a wide range of voice and data options. Integrated 2 Mbps wayside traffic is also available (at 34 Mbps).

As a result of the unit's mechanical design, built-in test functions and user-friendly PC interface, system installation is fast and affordable. System reliability is high as a result of advanced technologies, highly qualified components and stringent factory test procedures.

Long-haul Systems

The 9400LX digital point-to-point radio systems are recommended for the roll out of communications networks in rural or suburban zones. The 2, 7 and 8 GHz bands are internationally normalized frequency bands for low and medium capacity transmission. This series is suitable for public and private telephone transmission networks, including regional and local traffic, cellular base station interconnections and corporate networks, and multiplex transport for data networks, high speed digital terminal connections and utility networks. The systems feature capacities of 4 x 2, 8, 4 x 8, 16 x 2, 3 x 8 + 4 x 2 and 34 Mbps. Many features of the 9400UX systems are also incorporated in the 9400LX radios. The 9400LX systems exist in two versions: the ETSI cabinet version with a reduced height of 1800 mm forming a complete 2 + 1 terminal station that fits in a 300 mm wide cabinet, and the 19-inch subrack version.

Conclusion

Both the 9400UX and 9400LX systems are more compact than previous models yet offer more built-in features. As a result, the radios are easier to install and configure, requiring virtually no factory presetting. The outdoor portions blend more easily into the environment while the indoor elements, which are one-third smaller than previous-generation products, fit into the tightest spaces.

Combined with advanced, built-in diagnostics and testing facilities, these new microwave digital radio links require no routine maintenance. Furthermore, the units can be reconfigured remotely, with no on-site intervention for changes in bit rate, radio bandwidth and routing. The result is microwave radios that yield real economies in time and money.

Alcatel Telecom Radio,
Space & Defense Division,
Nanterre, France +33 (0)1 46 52 33 92.