Why Link Budget
Operators are rightfully focused on the service quality of a system and coverage is an important part of the service quality of a system. The aim of radio network planning is to balance coverage, capacity, quality, and cost so none of these can be considered in isolation.
Various factors must be considered during LTE system coverage planning and setting of these parameters will affect coverage radius and the quantity of base stations. LTE Link Budget,Coverage and design requirement must be analyzed in choosing parameters within the following parameter groups:
- System Reliability
- Specific Considerations
Achievable cell radius can be derived from the Excel based link budget tools. Network planning tool will provide site deployment specific simulation analysis to obtain the number of required base stations in the target area.
The coverage area offered by a 3 sectors and Omni site along with coverage planning flow is shown below
Conventional LTE Link Budget
The purpose of link budget in LTE network planning is:
- To use such factors as building penetration loss, feeder loss, antenna gain, and the interference
- Margin of radio links to calculate all gains and losses that will affect the final cell coverage
- To estimate the maximum link loss allowed based on the maximum transmit power of the terminal and eNodeB transmit power allocation.
- Coverage radius of a base station can be obtained according to the maximum link loss allowance under a certain propagation model. The radius can be used in subsequent design.
Link budget parameters are grouped as follows:
- Propagation (Transmission) related parameters, such as the penetration loss, body loss, feeder loss, and background noise
- Equipment dependent parameters, such as the transmit power, receiver sensitivity, and antenna gain
- LTE-specific parameters, such as the pilot power boosting gain, Multiple Input Multiple Output (MIMO) gain, edge coverage rate, repeated coding gain, interference margin, and fast fading margin
- System reliability parameters, such as slow fading margin
- Specific features that will affect the final path gain