Why to select UE Distribution, Channel Model and TDD Specific Configuration properly during LTE Planning
Here I write down about How to UE Distribution and Channel Model : Pedestrian vs High Mobility, TDD Specific Uplink and Downlink Configuration and Power Boosting Configuration selection during initial planning of LTE Network and why it needs to take care by radio engineer during LTE network plan.
UE Distribution and Channel Model: Pedestrian vs High Mobility
The impact of user distribution (pedestrian oriented vs high mobility focus) needs to be reflected in the channel model chosen for link budget estimation. On the other hand, appropriate proportioning between mobile and pedestrian users can also be configured in planning tool using the correct channel mode under each of the Environment entries.
If the target network is a dense metropolis like Hong Kong, Shanghai, using the wrong incorrect (higher mobility) channel models will have a higher demand on capacity and throughput estimation. On the other hand, for more mobility oriented cities in Western Europe, North America and Australia, using a more pedestrian oriented channel model will most likely result in an under-estimation of equipment requirement. This is because power control works much more efficiently in low mobility environment and its gain diminishes as the speed of mobility increases.
Hence, radio engineers should observe the local condition and make appropriate adjustment in their radio plan.
TDD Specific Uplink and Downlink Configuration
Due to the spectrum sharing and time division nature of TDD, there are seven Downlink vs Uplink assignment ration as well as nine Uplink/Downlink Pilot Time Slot vs Guard Band configuration available for radio planner’s selection. The different combination will have an impact on both the coverage and capacity availability especially when there is an extended range requirement.
Radio engineers are needs to determine the traffic ratio between downlink and uplink from the operator’s current network to assist in the selection of appropriate slot assignment ratio. Requirement of extended cell can also be determined via operator discussion and current network coverage review to minimize provisioning of guard band in LTE TDD network.
Power Boosting Configuration
Similar to most wireless systems, the perception of operator coverage is likely to be dictated by the “coverage” shown by UEs (e.g. number of signal bars). Hence, at initial LTE network launch when loading is low, a higher power boosting factor will help to improve coverage perception and reduce cell site count as RSRP is always a major requirement from operator.
However, once network traffic grows steadily, there will be a need to scale back power boosting as
- Power Boosting consumes extra radio card that could have been used for traffic
- The higher the MIMO order, the more radio card will be consumed
- More new sites are likely to be added to enhance coverage as well as capacity so Power boosting will indeed have a negative impact on coverage control in this situation.