12.3 ODAS – Outdoor Distributed Antenna Systems
As described above, micro cells can be a strong tool for reaching deep inside buildings with high capacity and data speed. The main challenge is the static capacity allocation that is attached to the individual micro cells and also the potential issue of having a compatible cell deployment of sector plans for mixed operations of 2G–3G–4G. Another drawback with traditional micro cells is the lack of multi operator support; each mobile operator will have to deploy their own individual base station for each technology in each cell. This can sometimes make it close to impossible to share the infrastructure for multi operator deployment of micro cells, due to lack of installation space for the equipment needed at the antenna site.
Unlock the Capacity from the Coverage
There is an answer to the problem of deploying traditional micro cells; ‘Outdoor Distributed Antennas Systems’ – ODAS. Like the active indoor DAS covered in Chapter 5, ODAS employs the same principle of a single centralized base station supporting multiple antennas allocated inside a building – with one difference we can use the same principle in an outdoor network for a micro cellular type of deployment utilizing all the advantages of the micro cellular type of deployment.
The principle of ODAS can be seen in Figure 12.7; the actual antenna deployment is similar to the traditional micro cell implementation, but instead of having distributed base stations at street level, ...