Co-location Interference Protection Filters
Interferences are likely to exist when RF base stations are co-located. That may cause receiver desensitization, overload and/or intermodulation product (IMP) interference, thereby degrading their system performances and increasing dropped calls. Co-location filters are used to prevent wideband noise and spurious signals to interfere from one system transmitter band into another system receiver band. Some examples of applications of the co-location filters are:
- GSM900 is co-located with 800 MHz cellular equipment
- PCS is co-located with GSM 1800 MHz equipment
- UMTS is co-located with PCS equipment, etc
The RFS family of diplexers and triplexers is designed to enable feeder sharing of several systems on the same site. Focusing at the highest technical performance standard and at easy installation, RFS have developed a broad range of innovative products for cellular band, GSM 900, GSM 1800, PCS 1900 and UMTS 2100, covering frequency bands from 806 to 2170 MHz.
Browse the print catalog to study some typical configurations for the dual band diplexers and the triplexer. In order to keep the schemes simple the shown sites have single-polarized antennas and single diplexers are used. Sites with dual-polarized antennas will require double diplexers, which are available in one enclosure or with flexible dual mounting bracket. Variants including DC pass for TMAs are also available.
Duplexers are used to simultaneously transmit and receive from a single antenna. They are three-port devices comprising a combination of transmit and receive filters with a common antenna port.
Duplexers are designed for various application based on operational frequency and utility. As an example, mobile duplexers are designed to handle low power and are very compact in size. Base station duplexers are designed to handle higher base radio power and generally designed to be mountable in standard equipment racks. All RFS duplexers are designed to provide high isolation between the transmit and receive ports.
RFS's QuikWave SMR receiver multicoupler consists of a front-end low noise amplifier, full band 18 MHz filter and splitters to provide 24 outputs. It is built with a universal power supply unit, which can work from various AC & DC inputs. It is ideal to use in SMR base station sites where feeder lengths are short and a TTA is not necessary. Optional filter kit maximizes site optimization, reducing interference.
- Improved system noise figure and sensitivity provides wider coverage
- Quadrature amplifier design gives high reliability and minimal degradation on failure
- Built-in test port allows for rapid on-site testing
- Optional filter kits optimize site performance minimizing interference.
- Universal AC-DC power supply simplifies ordering and installation.
- Isolated receiver output ports mean that unused ports can be left un-terminated reducing costs
Tower Mount Amplifiers (TMA)
The Standard TMA
The TMA separates the RF uplink (Rx) and downlink (Tx) signals through RF filters. In the uplink path the signal is amplified by redundant low noise amplifiers. If a malfunction occurs, the auto-bypass function is activated and an alarm is reported, ensuring system reliability at all times. The TMA includes a bias-tee function that injects the DC supply voltage into the amplifier from the inner conductor of the feeder cable.
The AISG TMA
The AISG TMA features the same RF functionalities and specifications as the standard TMA and includes communications features compliant with the AISG protocol that allow a remote monitoring of the equipment. All the AISG TMAs include an AISG output connector to an Antenna Control Unit (ACU) for Remote Electrical Tilt (RET). The complete AISG TMA system, including the control network interface unit (CNI) and the Bias-T, provides the DC feed and the alarm reporting at the Node B level or the OMC.
Tower Mounted Boosters (TMB)
For ongoing rollout with high emphasis on coverage objectives, the RFS Tower Mounted Booster (TMB) provides a low-cost solution for efficient coverage of low-density population areas. Allowing a reduction of the number of sites needed, the TMB minimizes capital expenditure linked to a project.
The RFS boosters are designed to be used, both for the EGSM 900 and DCS 1800 application. The booster system is designed to be located in the tower close to the antenna, ensuring the best possible BTS up-link sensitivity and providing the highest down-link power available on the market. The system requires one Power Distribution Unit and two TMBs for a dual-carrier solution. The Power Distribution Unit is placed in the base station cabinet, supplying power, controlling TMB and reporting alarm status. The TMB is an optimal solution for the following application:
- For compensation of large feeder loss.
- For coverage of low-density populated areas.
- For highway coverage where the traffic does not justify a large number of sites.
- For boosting cell coverage e.g. along coastlines.
- For boosting up low power signals from micro BTS.