Using microwave links in G3 and G4 mobile backhaul

Problem Description

Mobile operators are trying to follow increasing demands for faster packet transmission. However, the residual G2 part of the network still has to run simultaneously. Consequently,  in most cases both TDM and packed microwave transmission are necessary. Often, there are nodes to which optical fibres just can not reach.

Proposed Solution

Combining microwave and optical transmission techniques offers effective and efficient solutions. Due to the ability of packet transmission to adopt the transmission speed, adaptive modulation ACM is becoming an important characteristic of microwave point to point links. The TDM share of traffic gets much higher availability, because it uses lower modulation schemes (QAM4-16 for example). In good weather conditions higher modulation schemes are taking place. Bit rates at about 400 Mbit/s full duplex are normal for higher modulation techniques, combined with wide band radio channels of 56 MHz.

Basic Design

Network designers are always doing their best to protect the traffic in a network. Therefore ring topology is very common. Combining adaptive modulation, ring topology, layer 2 and/or 3 protection and fibre on some sites, very effective solutions are made available.

In case of heavy rain, causing transmission bit rate to decrease, routers are able to reroute the packet traffic.

Benefits

Above proposed solution enables mobile operators to avoid expensive civil works related to laying optical fibres. It also allows fast installation and deployment. The solution provides both, TDM and/or packet traffic, in an environment which is flexible and simple to manage with a common network management. Ability to use E1 (TDM transmission) eliminates any synchronisation problems.