Isolated reuse technology refers to 1*3 or 1*1 reuse with short reuse distance and severe interferences, radio frequency hopping technology has to be adopted. The aggregate of hopping frequencies needs to be far more larger than the number of TRX (more than twice), MA, HSN and MAIO parameter are used to avoid frequency conflict.
Let’s explain the feature of isolated reuse technology with an example. As shown in the figure, supposing there are 50 frequency carriers with 10MHz bandwidth, 14 of them are occupied by BCCH, 36 of them are used by TCH.
Planning with 4*3 reuse mode, each cell is allocated with 3 frequency carriers, the site mode is S4/4/4. With 1*3 isolated reuse, each cell is allocated with 12 frequency carriers. The actual frequency carriers available for the cell depend on isolated reuse rate (RF-LOAD: TRX of frequency hopping/total frequency carriers allocated by frequency hopping). To be specific, RF-LOAD can be up to 50% in theory, at this time:
The 6 TRX will use radio frequency hopping and can only be realized through radio frequency hopping technology, which means all these 6 TRX work on the 12 frequency carriers. By setting relevant parameters, make sure they won’t have co-channel conflict due to working on the same frequency carrier at the same time. When RF-LOAD is 50%, the largest site mode is S7/7/7 when using 1*3 frequency reuse technology.
For the frequency carriers allocated to one cell, TRX1 uses 1 of the 14 BCCH carriers, TRX2, TRX3, TRX4, TRX5, TRX6 and TRX7 work on 1 of the 12 carriers allocated to this cell in 1*3 mode respectively at certain time. All TRXs (2~7) have the same MA and HSN but different MAIO to make sure different carrier boards in the same cell won’t work on the same frequency carrier.