With the development of mobile communication technology, more and more new communication technologies (like 4G) will be adopted nowadays. Hence, telecom operators have to handle multi-system simultaneity and have to face the problem of re-farming spectrum resource for future. Frequency spectrum is a very precious resource for the operators, there is almost no free frequency band in their allocated frequency bands such as 900, 1800 and 2100MHz etc. can be the link frequency of Frequency Shifting Repeaters. However, there are some blind areas where fiber optic cable or dedicated cable is not allowed, and Frequency Shifting Repeater is the only solution in such cases.
For the above mentioned reasons, Helios develops and brings out Helios® Digital Multi-Band Microwave RRUs basis on DSP technology to resolve such problem. It consists of four parts: Indoor RF Unit (IDU), Donor Outdoor Unit (D-ODU), Remote Outdoor Unit (R-ODU) and Remote RF Units (RRU). For Synchronization method of Digital Microwave RRUs, Helios adopts Digital Pilot Synchronization method with normal crystal oscillators to ensure stable performance and long life working