Inter-cell Interference Coordination In LTE System

In LTE systems, the SC-FDMA and OFDMA technique are used for uplink and downlinktransmission, respectively. Because the orthogonality of different subcarrier, users can differ fromeach other based on these techniques. At the same time, the data stream is distributed over thesesubcarriers and so the interferences don’t exist among users in the same cell. But when thefrequency resource is universally reused in each cell of the system, the users suffer from the seriousintercell interference. Therefore, in order to improve overall system performance, Long TermEvolution (LTE) targets to reduce inter cell interference. Especially, the intercell interferencemitigation strategies include three schemes, which respectively are intercell interferenceRandomization, intercell interference cancellation and inter cell interference coordination (ICIC). Inthis dissertation, the critical technologies about inter cell interference coordination are reached. Also,some inter cell interference coordination schemes and its basic theory is reached. For the traditionalICIC solution, soft frequency reuse (SFR), the apparent disadvantage is that both of the cell-centeruser equipment (UE) and cell-edge UE cannot get frequency diversity gain. An improve scheme tothis question is reached. Different from the traditional scheme, each subset in adjacent cells consistsof a group of consecutive PRBs, for the new scheme, the group of PRBs which compose eachsubset in adjacent cells should distribute in the entire bandwidth evenly and discretely. In thisdissertation, the step about how to apply this scheme into SFR and frequency shift fractional reuse(FSFR) is into details.When the frequency resource is universally reused in each cell of the system, in each downlink(DL) subframe, the group of PRBs which compose each subset is distributed and the subset positionis not stationary but can be real-time variable. For uplink (UP) subframe, the subset is only bereal-time variable and the PRBs is consecutive because of using the SC-FDMAtechnique.In FSFR network, the improve scheme will be applied differently based on different overlapfactor, two method are reached in this article based on the overlap factor.Overall, because of distributed PRBs, both cell-center UEs and cell-edge UEs can get frequencydiversity gain no matter which subset they are using.