From GSM to LTE: An Introduction to Mobile Networks and Mobile Broadband

4.13 Backhaul Considerations

Owing to the high peak and average speeds of LTE, high-speed backhaul links are essential to ensure that the capabilities of the LTE air interface can be fully utilized. A three-sector eNode-B with a channel bandwidth of 20 MHz in each sector can easily achieve peak datarates that are three times 100 Mbit/s, that is, 300 Mbit/s in total. As eNode-Bs are usually colocated with UMTS and GSM base stations, the required combined backhaul bandwidth could hence be even higher. Today, three backhaul technologies are suitable for such high datarates.

Traditionally, copper-based twisted pair cables have been used to connect base station sites to the network. UMTS networks initially used 2 Mbit/s E-1 links and for some time, the aggregation of several links was sufficient for providing the necessary backhaul bandwidth. For LTE, this is not an option since peak datarates far surpass the capabilities of this backhaul technology. An alternative is very high speed DSL lines (VDSL) that can deliver datarates of the order of 100 Mbit/s. This might not be enough to cover the peak datarates required for a cell site but is a much better alternative compared to E-1 link bundling.

For higher datarates, copper-based cables have to be replaced with optical fibers. While the datarates that can be achieved over fibers match the requirements of a multiradio base station, it is costly to deploy as in many cases new fiber cable deployments are required for buildings and often ...