In an LTE system, a Sounding Reference Signal (SRS) is a signal for measuring wireless channel information between a User Equipment (UE) and an Evolved Node B (eNB).
In the LTE system, an SRS sequence ru,v(α)(n) (wherein, α is an integer between 0 and 7) is obtained by performing cyclic shift on a basic sequence ru,v(n) (wherein u represents a group number of a sequence, v represents a sequence number within a group, and n represents the n-th symbol of a pilot sequence), and is subjected to physical resource mapping to obtain the SRS. SRSs obtained by performing cyclic shift on different basic sequences are not orthogonal to each other, but are correlated with each other. Namely, there is interference among the SRSs. However, SRSs obtained by performing cyclic shift on the same basic sequence are orthogonal to each other, and are uncorrelated with each other. Namely, there is no interference among same-frequency SRSs.
A UE transmits a target SRS to an eNB corresponding to the UE regularly according to parameters configured for the eNB, such as a bandwidth, a location in a frequency domain and a period. an SRS transmitted by the UE will arrive at both the eNB corresponding to the UE and an eNB other than the UE-corresponding eNB. An SRS arriving at the eNB corresponding to the UE is referred to as a target SRS, while an SRS arriving at an eNB other than the UE-corresponding eNB is referred to as an interfering SRS. The eNB performs channel estimation to obtain channel information according to the received target SRS, and further performs operations such as frequency-domain selective scheduling, close-loop power control, or pre-coding according to the obtained channel information.
However, basic sequences of SRSs transmitted by UEs in different cells are generally different, so a target SRS transmitted by a UE to an eNB corresponding to the UE may be subject to interference by another SRS, i.e., adjacent-cell same-frequency interference.
FIG. 1 is a schematic diagram showing interference with a target SRS from a target UE by a same-frequency interfering SRS from an adjacent cell in an LTE system. As shown in FIG. 1, cell 1 has two adjacent cells, i.e., cell 2 and cell 3. A target UE0 transmits a first target SRS to an eNB in cell 1, a first interfering UE1 transmits an eNB in the cell 2 a second target SRS forming a first interfering SRS of the first target SRS, and a second interfering UE2 transmits an eNB in the cell 3 a third target SRS forming a second interfering SRS of the first target SRS. The eNB in the cell 1 receives the first target SRS, the first interfering SRS and the second interfering SRS simultaneously. The first interfering SRS and the second interfering SRS may interfere with the first target SRS. It thereby can be seen that the target SRS is a valid signal transmitted by the target UE to the eNB corresponding to the target UE; and the interfering SRSs are interfering signals transmitted to the same eNB by interfering UEs in adjacent cells.
At present, with LTE, adjacent-cell same-frequency interference can be controlled and coordinated using methods such as scheduling, power control, Inter Cell Interference Coordination (ICIC), or the like. However, the aforementioned methods cannot eliminate adjacent-cell same-frequency interference completely, so the target SRS transmitted by the target UE is still subjected to interference by a same-frequency interfering SRS from an adjacent cell.
Now, the 3rd Generation Partnership Project (3GPP) organization needs to evaluate performance of an LTE system in a non-ideal state. Thus, it is required to simulate a target SRS received by an eNB, which target SRS is subjected to interference by an interfering SRS; and channel estimation is performed according to an SRS obtained by processing the target SRS to complete the performance evaluation.
In an existing simulation, an SRS Y received by an eNB is obtained according to a formula
      Y    =          SH      +                        ∑                      k            =            1                    K                ⁢                                  ⁢                              S                          I              k                                ⁢                      H                          I              k                                          +              N        0              ,wherein S represents a target SRS transmitted by a target UE; H represents a target channel carrying the target SRS; k represents a sequence number of an interfering UE, k⊂{1, 2, . . . , K}; SIk represents an interfering SRS sequence transmitted by a k-th interfering UE; HIk represents an interfering channel carrying the interfering SRS transmitted by the k-th interfering UE; N0 represents channel noise; and
      ∑          k      =      1        K    ⁢          ⁢            S              I        k              ⁢          H              I        k            represents the received interfering SRS.
At present, the target channel and an interfering channel in the formula need to be generated according to a channel-generating process of a Spatial Channel Model (SCM) in the 3GPP. Generating an interfering channel includes generating a large-scale fading gain and a small-scale fading channel. However, due to effect of factors such as multipath, angle spread, time delay and the like, the generation of a small-scale fading channel is quite complicated and time-consuming.
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