Mobile Backhaul

2.4 Packet Based Backhaul Networks

The previous sections discuss many drivers strongly pushing existing MBH networks to change, and new MBH networks to be different; they will be based on packet technologies and networking. In a fully packet-based MBH network there are no more PDH and SDH/Sonet nor ATM equipment, but it consists of packet switches and routers (layer 2 and 3 devices) connected directly to each other by physical (layer 1) connections, for example by optical fiber or microwave links. Packet networks and networking will be discussed more in Chapter 04 and technologies and equipment used in Chapter 05; below are some general observations.

2.4.1 Physical Network and Topology

Network basic structure and topology will often look quite similar to that of the earlier MBH networks (see section 2.2), as the basic economics of the physical network (layer 1) optimization do not change much – physical links are still shared as much as possible for several base station sites and the un-shared final links to base station sites are kept as short as possible.

The nodes used in the traffic merging and concentration points are obviously different in the packet-based MBH networks – they are, for example, Ethernet switches and IP/MPLS routers, i.e. layer 2 and layer 3 devices in packet networking terminology; some examples on possible (access) network solutions are presented in Chapter 10.

In general access tiers are more often implemented based on layer 2 solutions (e.g. Ethernet switching) ...