In this second post, we will continue analyzing the Extended cell range feature, specifically we will focus on analyzing scenarios 1 and 2, where cell radius is for coverage in 4G below 100 Km. For escenario 3, please go to the first part of post.
Cell Radius for coverage in 4g below 15 Km
This function is recommended when the maximum coverage distance of a cell is less than or equal to 15 Km. For more than 90% of use cases, LTE configuration uses the default cell range of 15 Km or below. This is a basic function and it is active by default so it does not need to be activated or deactivated.
Some of the parameters involved in the settings for this feature are:
- Preamble format: Set to the default value.
- Cell radius: This values should be same or bigger than the actual cell radius
- Cell Radius Start Location: This parameter should be less than cell radius and the difference between both parameters should be less than 100000.
Preamble format is very important configuration related to the random access procedure. PRACH preamble varies depending on the preamble format.
Format 0 and format 1 are made up of single copies of PRACH converted in time domain. Format 2 and 3 are made up of two copies of PRACH sequence concatenated. The longer T_SEQ would help decoding PRACH under noised condition because it provide longer correlation window to detect PRACH. Now let’s look at T_CP part, you can notice format 1 and 3 has much longer T_CP comparing to format 0 and 2, longer CP would give better tolerance in fading environment and reduce ISI even in highly fading environment.
Cell Radius above 15 Km and below 100 Km
This function should be enabled when the maximum coverage distance of a cell is in the interval of (15 km, 100 km]. Set the cell radius based on the actual coverage radius (the cell radius can be greater than the actual coverage radius) and configure the preamble format based on the cell radius.
Activating this feature leads to issues with another LTE features, so you must take into consideration this when enabling the feature.
- TTI bundling
- Uplink antenna diversity
- PUSCH IRC
- Downlink MU-MIMO in TM9
- Massive MIMO introduction
- UL CPC
- CSPC
- Static Multiple Beam
- Intelligent beam shaping
To activate this feature you just need to modify the cell radius to a value between 15000 and 100000 and modify the preamble format respectively.
