LTE-A Implementation Scenarios: RF Planning Comparison

RF Link Budget

Like any wireless system, radio frequency link budget need to be calculating for LTE to in order to estimate the coverage of the sites and ultimately determine how many sites is required (Enigmatic Consulting, 2007).

Figure 2 resumes the link budget calculation that will be followed during this paper.

Figure 2.

General radio link budget

In order to calculate the link budget, the radio path losses and the equipment output powers and sensitivities must be taken into account for both directions.

Effective Radiated Power

In radio telecommunications, Effective Radiated Power (ERP) is determined by subtracting system losses and adding system gains. ERP takes into consideration transmitter power output (TPO), transmission line attenuation (electrical resistance and RF radiation), RF connector insertion losses, and antenna directivity and is calculated as in Table 1.

• 2.1.1. Transmit RF Power: Is the power at the output of the equipment, in the downlink direction, it is associated with the eNode-B and in the Uplink direction, the transmit power is associated with the UE.

• 2.1.2. Transmit Diversity Gain: In LTE, more than 2 antennas could be used to transmit information, this will lead to coverage improvement and the gain obtained from transmits diversity is obtained from the equation:N_T is the number of transmit antennas

• 2.1.3. Transmitter Loss: It includes all the losses between the output eNodB and the antenna such the feeder loss, filters and duplexer’s losses.

• 2.1.4. Transmit Antenna Gain: is the Gain of transmitter antenna, it is a function of the horizontal pattern, vertical pattern, and number of elements that make up the antenna array. In our link budget we have assumed that all LTE-A deployment scenarios will have the same antenna gains of 16 dBi for the eNode-B and 0 dBi for the UE as stated in Evaluation methodology proposed for LTE-A in 3^rd Generation Partnership Project (2008, pp. R1-084026).