In my previous post of common backhaul, I have given a high level design of for the common backhaul used by the operators to serve 3G. But with that design, RNC need to be equipped with n*E1 links to serve the nodeB. We have the following disadvantages with design:-
1. As the nodeB traffic will increase, operator need to increase the E1 ports on RNC.
2. Adding E1 ports on RNC is really an expensive solution.
3. More operations and manageability.
4. Number of more physical links.
5. TDM means end to end E1 will be blocked whether traffic runs over it or not.
To address the above mentioned issues, operators need to add an aggregator router which would serve nodeB traffic towards the RNC and vice versa. By adding an aggregator router, operators can drastically reduce the cost of the network without making much change in the network.
What operators need to know before adding an aggregator router:-
1. An aggregator must support channelize STM port towards nodeB side.
2. An aggregator must support UN-channelize STM port towards RNC side.
3. Option to create an IMA group on aggregator.
4. Must support PWE3.
5. Static routing if require dynamic routing also.
So the new design will look like after adding an aggregator router:-