WCDMA Antenna System Design in Detail
During detailed design, the main task is to determine the exact type and placement of the Antenna, to ensure sufficient coverage to meet the requirements. During this process, the physical properties of the Antenna must be kept in mind, as they may affect the design of the Antenna system.
Many indoor Antennas are available with patterns suitable for different situations. These Antennas may be the ceiling or wall. The omni-directional Antenna have the lowest gain (about 2 dBi), but emits a 360 degree azimuth. Omni Antenna radiation pattern allows it to collect signals from all directions, which partially compensates for imperfect reflection and scattering of the signal found in the room.
Directional Antennas have a single beam focused in one direction, and the gain in the channel’s may reach 7 dB, depending on the horizontal beam Antenna. These Antennas can be placed in one corner of the building, providing a good coverage area for a long narrow passage. Bi-directional Antenna, sometimes called the train Antenna, there are two focused beams on each side, but reduced the directional gain of 5 dBi in the channel because of the vision of two beams of radio compensation.
They can serve as highways and corridors, or to provide continuous coverage between the two long-areas pass. Suitable types of Antennas and the orientation can be determined either on the basis of experience (manual) or by a network planning tool. Antenna placement is a function of three-dimensional geometry of the building. High-rise buildings with vertically stacked floors may require one or more Antennas on each floor, because the floor and wall penetration are significant, and also because of other-cell (s) interference may be high.
The required length of the cable increases with the number of floors in the building. The number of power dividers or directional couplers, which allow to transmit signals from the main cable and increases. Consequently, some of the high office towers to fiber-optic cables and repeaters to carry signals over long distances from the radio. In contrast, shopping centers stadiums or fewer Antennas may require to reach, because they have less internal barriers and more Los media type distribution.
However, when multiple cells are to be used, typically for reasons create much more difficult to control and transfer of cells overlap in these environments. Directional Antennas and clever positioning of the Antenna can help increase the isolation between different Antenna beams.
Placing the Antenna inside the building should not only ensure proper coverage, but also to handle the transitions between the internal and external nodes. These two cases are discussed separately subcoating using the same or a different frequency in relation to the open cells. When carriers are used in different indoor and outdoor, whether transition zones are adequate verified, ie large enough to allow the UE to perform compressed mode measurements and maintain a handover between frequencies. When the same vehicle (s) used in indoor and outdoor insulation between the inner / outer cells is provided by minimize the amount of interference between transmitting and systems.
Placing the Antenna to ensure the safety of the general public EMR moving in close proximity to the radiating elements. EMR regulations limit the maximum power of the radio signal, which can be allocated, and also specify a minimum distance that must be maintained between the radiating element of the Antenna and the public. These restrictions ensure that RF exposure below dangerous limits set by the rules. Among others, EMI regulations determine the maximum power of the Antenna, which in turn determines the distance that can be sustained between the mobile node and the subscriber. Therefore, an indoor network planner must take into account all these problems and planned equipment loss so that total loss within the desired range.
In contrast to the macro network planning, for which the RF planning tool is always used, indoor planning can be done manually or by using the private network planning tool. The difference is mainly due to the need to plan for coating the inner system rather than coverage and capacity (although some types of internal coating must be provided for different concentrations of traffic). Capacity can be provided relatively easily in closed systems by upgrading to a dedicated repeater node or by adding multiple sectors / carriers.