One of the key challenges for the development of rural networks is the cost of the backhaul to connect base stations to the core of the network. The average revenue per user is quite low in those areas, thus making the business case difficult for the mobile operator.
Microwave is generally the solution when copper or fiber line line are not available. It covers distances in the range of 30 kilometers with one hop and up to a few hundreds with multiple hops. Beyond this limit or when geography doesn’t allow for line of sight, satellite backhaul is the alternative solution.
Operators deploying satellite backhaul must pay attention to the high cost of bandwidth and the delay to transmit the signal over a satellite link. To overcome these challenges compression solutions allow for reducing the amount of bandwidth transmitted over satellite.
For legacy TDM base stations, those compression functions are implemented in the external multiplexer equipement used to adapt the circuit switched Abis interface to pachet switched satellite transmission. The same multiplexer can also implement the Local Switching functionality developped by Cell & Sat.
Figure below illustrate satellite backhauling towards TDM BTS as well as new generation IP interface BTS.