7.2 3G Network Planning Procedure

Compared with the second generation mobile communication, it is difficult to forecast different service models in the third generation system network owing to introduction of several kinds of  high bit rate services. As for radio network planning, in any case, it is required to calculate the link budget, capacity and number of NodeBs, estimate the coverage of base station and design the parameters. In addition, it is required to design the whole network, calculate the number of channel units, capacity of transmit lines, RNCs, MSCs and other units in a base station.

In network planning, performance measurements (such as dropped call rate and GOS) should be introduced to measure the network performance. High-bit rate services are provided at the cell area where base stations are covered equably, while low-bit rate services are provided to the edge of cell. The coverage can be designed as continuous coverage or hotspot coverage. You should estimate coverage of base station carefully according to different services and different implemented policies. Radio network planning can be divided into the following phases:

l   Preparation Phase

1)      Confirming Coverage Object

2)      Confirming Capacity Object

3)      Confirming Coverage Policy

l   Estimation Phase

1)      Estimating Cell Service Amount

2)      Estimating Cell Capacity

3)      Estimating Coverage Area

4)      Calculating Capacity and Link budget

l   Design and Adjustment Phase

5)      Wireless Coverage Optimization Adjustment

6)      Control Channel Power Design

7)      Pilot Design

8)      Soft Handover Parameter Design

9)      PN Offset Handover

After the above phases, you get to know the radio network features and confirm control channel allocation and design handover parameters, and then you may analyze the coverage of base station in detail. As for some cell, inter-cell interference vs. total interference ratio is unique. During the process of planning, you can continually take an analysis to the network and evaluate the interference ratio to estimate the coverage in different cells. Such iterative process may be repeated until the convergence of coverage is achieved. Design tools can be adopted to realize the process automation and in the meantime detect leaks in the coverage. Usually, the coverage in 3G network service is not equable, which would lower network performance. On the one hand, the interference in the service-intensive area gets more, resulting in low quality. On the other hand, it is not necessary to get high quality, for it will result in a waste of resources. System effectiveness can be improved with the method of self-adapting controlling cell radius, antenna direction and uplink received power threshold. Cell radius can be varied with pilot power adjustment. If signal-interference ratio (SIR) is higher than the required value, cell radius can be increased. If not, cell radius can be decreased. The uplink/downlink cell radius can be balanced by increasing/decreasing uplink received power threshold. In the configuration of separate sectors, the communication quality of the base station can be balanced by changing central angle of each sector.