In the first special case in which the interference is small (27).
Inter-user interference is small when the moving speed is low, so there is higher multiplexing gain of MU-MIMO benefits.
This means when the interference is small and the price is small, the power is convex as a function of the price.
It is clear that when interference is small enough, the most dominant part will be the χ2 which agrees with Raleigh fading channel where no MUI exists.
The largest gain in EE is achieved when the ULU-DLU distance is maximum (i.e., (widehat {text {AOB}}=pi )), in which case, the intracell interference is smallest.
Since the influence of the interference is small in short target distance, the optimal TP is shown to be higher in shorter target distance.
If I PU is below the threshold, the interference is small and SU can share the frequency with the PUs with appropriate transmission power.
When the FBS is far from the MUE or the channel between the FBS and the MUE is in deep fading, the interference is small, so PMI should be applied at the FBS to maximize the signal power from the FBS to the FUE.
Thus, the above condition states that as long as the ratio between the interfering channel and the direct one, i.e, the direct channel between the transmitter and the receiver, is lower than a certain threshold, or, in other words, the interference is small enough, then a solution for game (17) exists.
Partition the cells into three groups: left-shifting group B L, right-shifting group B R, and non-shifting group B M. Step 2: If the corresponding interference is small for l i, i.e., it meets the condition of formula (8), then the shifting strategy which coincides with the W-TDD method [19] is adopted, and if the corresponding interference for l is too big, the C-TDD method is adopted.
