9.7 DL C/I calculation

The relationship between the contributors of the interference in a OFDMA network is illustrated in Figure 205.

Figure 205: Illustration of the interference mechanism in the OFDMA module

Figure 205 illustrates the interference mechanism in the OFDMA module where the inter-system or also called self interference is noted “Iinter” and the interference from an “external” interference system is referred to as “Iext”. In the SEAMCAT OFDMA implementation, the term “BS” and “cell” have the same meaning.

The C/I calculation in DL is calculated as

                                                                                 (Eq. 46)

where C(j,k) is the received power at the k-th user from the serving BS, i.e., the j-th BS

                                                           (Eq. 47)

and where  is the power of resource block and effective_pathloss is defined as in Section ‎7.6.1.

I(j,k) is the sum of the interference power

                                                                                          (Eq. 48)

where

• I_inter (j,k) is the adjacent cell interference (i.e. from the same victim system, i.e. denoted inter-system interference;
• I_ext(j,k) is the interference from external interfering system(s) in adjacent channel, i.e interference power into this resource block including ACIR;
• N is the noise floor.

 (Eq. 49)

 (Eq. 50)

I_ext(j,k) is the interference to the the victim UE_j,k from N interfering link transmitters (ILT). Note that the ACIR (Adjacent Channel Interference Ratio) is implicitly taken into account when both unwanted and blocking mechanism are summed in the computation. The unwanted and blocking are defined as follow

       (Eq. 51)

for each of the victim UE_j,k’s frequency where the DL information is received. The ILT can be any generic systems or a BS/UEs of a cellular system.

  (Eq. 52)

at the victim system frequency. Where N_RB is the number of RBs (i.e. subcarriers) requested per UE, and M is the maximum number of RBs per BS.

                (Eq. 53)

where NoiseFigure_UE is the noise figure of a UE.