Seamless coverage in complicated environments, such as large buildings, underground structures, tunnels, subways and airports is not an easy task even for advanced wireless communication systems. These locations have blind zones, which are generally small but essential for the complete coverage. For example, when major events are held in large hotels or conference and exhibition centers, poor signals may disrupt security operations, which in turn may adversely affect the event. Blind areas inside tunnels may seriously complicate routine operations or traffic police’s efforts to handle accidents. Weak wireless signals along railways may undermine transport safety and productivity. Security personnel on patrol in key locations, such as subway stations and airports, may fail to communicate with the command center through wireless networks simply because the steel structures of buildings block signals.
Hytera has developed a signal enhancement solution for weak-signal areas based on the following principles:
(1) Faster and more cost-effective than the construction of trunking base stations
(2) Wider base station coverage without additional frequency resources
(3) No interference with existing base stations and no adjustment to existing system and base station parameters
The solution uses bi-directional amplifier (BDA) to transmit signals between base stations. These BDA can be installed outdoors to extend the coverage of base stations to blind zones. They can also be applied in indoor distribution systems to amplify signals. Located separately at local and remote sites, these devices support multiple signal transmission via RF cables and optical fiber to cover geographically varied blind zones.
1.Select channels through software-defined radio (SDR) technology
The SDR technology can amplify signals over selected channels and shield undesired signals to keep frequencies free from interference within the transmission area and stabilize the output power. Highly compatible, the technology can be widely applied in the following systems: conventional communication systems, MPT-1327 Analog Trunking Communication System, and digital trunking communication systems such as TETRA, PDT, and DMR.
2.Avoid interference from overlap areas and ensuring voice quality through an uplink noise channel switch
The solution includes a channel switch. When no calls are made between two-way radios within a coverage area, a selected channel on the multi-channel module can be disabled automatically to minimize the impact on base stations. In this way, the overlap area incurs no interference, thus ensuring high voice quality within coverage area.
3. Interference cancellation system
As a signal amplifier, the interference cancellation system (ICS) is unrivalled in terms of coverage, receiving sensitivity, and voice quality.
Coverage for the Traffic Police Building in Zhuzhou, Hunan, China
Coverage for the International Conference & Exhibition Center in Guangzhou, China
Extended trunking coverage for the police in Taicang, Jiangsu, China