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Multicore boosts microwave transmission range

Posted: 14 Jun 2013 ?? ?Print Version ?Bookmark and Share

Keywords:Fibre-optic? microwave? multi-core radios? transmission links? network?

Fibre-optic cables do hold an ultimate capacity advantage over microwave, but a great many communication links do not require the full throttle of fibre. As lower-cost and quicker-to-deploy microwave technology increases in capacity, microwave becomes advantageous in more deployment scenarios heretofore addressable only by fibre. Breakthrough multi-core radio technology now boosts microwave transmissions into the multi-Gb/s capacity range where it has never ventured before, enabling system designers to use cost-effective microwave solutions that are considered too expensive to implement with fibre.

Multicore technology not only boosts capacity but increases link distance while decreasing power consumption and form-factor, further reducing total cost of ownership. Remotely configurable, multi-core radios cut the operating expenses of transmission links today while assuring inexpensive network modernisation in the future.

The architecture
The breakthrough multi-core radio architecture is based on a parallel radio processing engine built around Ceragon's in-house base band modem and RFIC chipsets. Optimised for the processing of multiple radio signal flows, the architecture multiplies the capacity and increases the system gain over current technology. Using common processing resources at the kernel of the radio terminal, the multi-core system reduces power consumption and maintains a small form-factor, making it especially attractive in numerous network backhaul scenarios, such as fronthaul and small-cell backhaul.

A parallel radio processing engine differentiates multi-core radios from other compact multi-carrier solutions that are really nothing more than multiple radio systems compacted into a single box. These do not offer the many benefits of the centralized resources of multi-core technology.

Flexible operating modes
Multicore radio technology is inherently versatile and suitable for many different deployment scenarios. The multi-core radio can operate initially as a high-capacity, single-core solution to suit a host of today's transmission requirements. As network evolution warrants, the second core can be activated remotely for optimised performance in myriad additional applications to fit virtually any backhaul, fronthaul, or other deployment scenario at far higher microwave capacities than ever before.

Basic performance: To illustrate, consider a generic, 1+0 single-core radio with high performance in terms of capacity, link distance, and antenna size:

Operating in single-core mode, the radio will have similar performance to the standard, but it will provide additional capacity due to its advanced modulation (2048QAM).

Doubling the capacity: Turning on the second core automatically doubles the bandwidth of the single-core radio (whether we use an adjacent frequency channel or the same one with orthogonal polarisation, such as XPIC). This significant capacity boost is achieved without compromising system gain or availabilitysince it comes about from the use of an additional carrier at the same modulation and same Tx power and Rx sensitivitywhile maintaining the same small form-factor. Effectively, it is a pure doubling of capacity without any trade-offs.

Doubling the link distance: The multi-core radio can also be leveraged to increase link distance. In our implementation, the FibeAir IP-20C, the multi-core equipment splits the transmitted bitstream between its two cores using Multi-carrier Adaptive Bandwidth Control, which, in turn, makes possible a lower modulation scheme that significantly increases system gain (both higher Tx power and lower Rx sensitivity). Increased system gain contributes to greater signal distance. The multi-core radio can achieve significantly longer link spans even up to double the distance.

For example, let's consider a case where the multi-core radio, in 1+0 configuration (only one core is activated), transmits 260Mbps with 2048QAM modulation over a 28MHz channel. Activating the second core makes it possible to reduce the modulation to 64QAM and yet transmit more capacity: 280Mbps (2 X 140Mbps over the 28MHz channel). Reducing the modulation from 2048QAM to 64QAM also delivers a 4dB improvement in Tx power and a 15dB improvement in Rx sensitivity yielding an overall increase of 19dB in system gain. With this improvement, we can double the distance of the link and, at the same time, enjoy an additional 20Mbps of overall capacity.

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