Desynchronisation between coexisting radio local loop systems based on DECT

The Digital Enhanced Cordless Telecommunication System (DECT) is gaining acceptance in environments different from those for which the system was designed, in particular outdoors environments such as radio local loop (RLL) and public cordless systems. The main difference between indoors and outdoors is that in this latter environment the signal propagation is not limited between walls, and therefore, is more interfered. When several operators compete for one service using the DECT, they have to share the band allocated to the DECT. There are several ways to share the available frequencies, one is spectrum splitting among all operators. This technique loses capacity because dividing the channels leads to a poor trunking efficiency but, all the systems are independent and there is no need for any synchronisation between them. The second method allows each operator to access the full available spectrum. It can be seen that this technique has better results than the former if all the systems are synchronised but, if not, there is an increment of the interference that produces a loss of capacity. This paper focuses on the effects of desynchronisation between systems sharing the same frequencies.