Integrating narrowband PMR networks with broadband LTE networks can provide a winning combination of secure, reliable, mission critical push-to-talk voice and messaging communications with access to fast mobile data services, such as sending and receiving images, video and querying databases. Combining the two technologies also enables voice communications to be extended beyond the coverage area of the PMR radio network and allows two-way radio and cellular smartphone users with a push-to-talk (PTT) app on their device to communicate both within and outside the PMR coverage zone.
There are two main ways to integrate narrowband PMR and broadband LTE networks. The first way interconnects two separate systems using a gateway. This is usually referred to as a ‘hybrid’ network, as it is allows two discrete networks to be interconnected. The second way is to implement a ‘converged’ network, which combines both technologies onto the same service management platform.
Hybrid networks
Hybrid networks can take a variety of forms. These are largely determined by how the hybrid network manages to access LTE frequency spectrum. If the PMR network operator has no assigned LTEfrequency spectrum then the easiest way to access some is to overlay a dedicated broadband service on top of a commercial mobile operator’s network using VPN (virtual private network) technology.
A second way, if again no frequency spectrum is available, is to implement tactical islands of dedicated 4G LTE coverage around key sites using small fixed or mobile LTE base stations. Spectrum would have to accessed via an MNO or other LTE spectrum license holder. Hytera and its subsidiary Teltronic can provide a variety of LTE base stations including fixed, mobile and man-portable.
A third solution is where the PMR network operator is provided with its own dedicated licensed LTEspectrum by a national government or regulator. The operator can then build and operate its own dedicated private LTE network on a local or even national level and use it in conjunction with its existing PMR network.
Converged networks
A more advanced and efficient solution is to combine both PMR and LTE technology onto a single converged platform. For example, in 2017 Hytera launched its narrowband and broadband LTE-PMR Converged Communication Solution, which provides a unified management and services platform for both technologies. The Hytera Base-Band Unit (BBU) supports both LTE and PMR for dual mode operations or to enable a smooth transition from narrowband to broadband. The Hytera Remote Radio Unit has been designed to support multiple modes and standards such as LTE and PMR using a software defined radio (SDR) architecture.
The key to managing a converged LTE/PMR network is the enhanced Trunking Core (eTC), which delivers a unified platform to manage trunking services provided by both technologies. The Hytera EMS (enhanced management system) provides a unified management for both LTE and PMR and integrates terminal management sub-systems, user policies and so on. For example, this allows the system to identify and manage subscriber IDs and profiles as users move between LTE and PMR networks.
Hytera has also developed an integrated base station (iBS), which combines the RRU, BBU and eTC into one small unit. Again, the iBS supports multiple modes, including LTE and PMR. It can be deployed as an outdoor base station within a network or as a discrete, standalone system. The iBS supports multi-site networking, but it can also be used to provide separate narrowband and broadband networks. On the devices side, Hytera offers the PDC760 DMR/LTE and PTC760 TETRA/LTEhand portable, multi-mode Advanced Radios enabling users to switch easily between LTE and PMR modes.
In addition to the multi-mode radios and its extensive portfolio of DMR terminals, Hytera has recently added some Push-to-Talk over Cellular (PoC) LTE devices.
For more information on Hytera solutions for hybrid and converged networks contact us.
