Telecom Techniques Guide


Why to evaluate operator existing Network condition for InterRAT in LTE planning

Radio planning engineers need to understand the existing operator’s network configuration as well as its footprint. This is particularly important before designing any network that requires commitment on KPIs later. In any Greenfield LTE deployment, there will be a need for InterRAT handover either due to coverage hole within the LTE network or on the fringe of the LTE network to area beyond its coverage.

Hence, understanding the current status of the underlying network from both a coverage and performance perspective is critical in finalizing the LTE network design and capacity planning.

For example,

  • It is unwise to place an InterRAT border in a heavily congested area.
  • Similarly, it is not appropriate to locate an InterRAT border in location where the existing 3G or 2G network is of poor coverage.
  • It is also not recommended to place any InterRAT border along interRNC/BSC or inter PLMN border area.
  • Try to locate LTE InterRAT border in area where operator network is offering good throughput to reduce the level of future operator complaint.

In order to make these InterRAT boundary decision intelligently, it is reasonable to request traffic loading and performance information from the operator regarding the existing network both within and on the edge of the proposed LTE network

Highway and Tunnel Coverage Requirement

Most Operators will require good coverage along major highway and major tunnels due to the strategic visibility of services. In both situations, traffic likely to be high speed but low volume so smaller capacity provisioning is acceptable.

In LTE, this means either smaller bandwidth, small transmit power or even less MIMO complexity as long as coverage is fine. One major problem for this type of coverage is the feasibility of installation due to for example space and air conditioning restrictions inside tunnel or location restrictions along major highway so Radio planner also need to ensure the appropriate type of eNodeB is chosen. In general, it is NOT a good practice to rely on the external eNodeBs to provide coverage inside the tunnel.

Terrain and Clutter Database Availability and Accuracy

It may not appear to be important but the resolution and accuracy of terrain and clutter information will have a BIG influence on the reliability of the final network design. Clutter resolution comes as 10m, 25m, 50m, 100m and beyond depending on the price paid as well as the location of the clutter. For instance, downtown area will require higher resolution while rural town can accept data of a lower resolution nature.

Besides data resolution, it is also important to ensure the clutter data is not shifted from the real structural location.

Another important factor is when the database was made available and when was the latest update made. It is very worthwhile to valid the clutter information against other sources of information e.g. Google earth (which is normally 3 to 6 months late) to ensure critical structures have been included.

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