Fractional frequency reuse (FFR) partitioned the usable spectrum in to number of sub-bands and assigns a given sub-band to a cell in a coordinated manner that minimizes inter-cell interference.
For example:
- For N = 1/3 FFR re-use pattern, each cell would be assigned a sub-band spanning 1/3 of the available spectrum.
- Basic N = 1/3 FFR results in an improvement in SINR due to reduced interference levels; however, due to a reduction in available BW, the aggregate throughput is typically about 75–80 percent of the aggregate throughput of an equivalent system employing N = 1 reuse.
- However, due to the improvement in SINR, any coverage gaps for cell edge users can typically be mitigated, although total cell edge user spectral efficiency compared to N = 1 performance does not typically improve significantly.
- It should also be noted that use of FFR in an LTE OFDM system will reduce the available number of RBs that can be scheduled and hence the peak throughput, potentially impacting the possible quality of service for high bandwidth applications.
Fractional Frequency reuse can be done with two types:
- STATIC FRACTIONAL FREQUENCY REUSE
- ADAPTIVE FRACTIONAL FREQUENCY REUSE
