A Framework for Push-to-Talk Service Implementation using Voice over LTE (VoLTE) and its Key Features

With the recent advancement in wireless technology and enhanced smartphone capabilities, there has been an apparent increase in the utilisation of Push-To-Talk over Cellular (PTToC).  PTToC is a feature which can only be implemented when Voice-over-Long Term Evolution (VoLTE) capability is installed in the cellular networks. PTToChas wide coverage since it uses a cellular network. Moreover, PTToC is implemented as a data call. Therefore, calls can be made even when voice channels are congested. A pictorial representation of PTToC is shown in figure 1 below.

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Figure 1: An illustration of PTToC using various cellular networks.

The Role of PTToC in Mission Critical Communications

With the advancement in telecommunications, the PTToC utility is currently being used in many commercial applications, for example, Public Safety networks and business critical sectors. This technology works in harmony with Mission-Critical applications offered by the Land Mobile Radio (LMR) networks. Today’s cutting edge communication techniques have enabled organisations to combine traditional voice communication with growing data sources in order to make better and faster decisions. PTToC is an essential component of LTE-based solutions. Moreover, encrypted Push-to-Talk over cellular offers enhanced features such as location tracking, group texting and image messaging for real-time communications.

Key PTToC Capabilities

PTToC offers multiple benefits for the agencies and organisations in commercial and business sectors by giving mission critical services. A brief description of the PTToC salient features is given below.

Instant Global Connectivity

Since PTToC is operating on modern digital cellular network standards, the entire world has now same network infrastructure. Public safety agencies can now connect any where around the globe in the same way as it would connect with the terrestrial-based trunked radio systems.

Fast and secure public safety networks

PTToChas connection speeds equivalent to land-mobile radio communication. Thus,byintegrating the benefits of PTToC and LMR, users can be facilitated with seamless mobile communication. With the introduction of encrypted PTToC, organisations are able to increase the number of users, in order to make them capable of communicating over a DMR network in a secure way.

Flexibility in critical communication services

This technology is well suited to a wide-range of devices. The user can use this technology with their choice of device. PTToC is very handy so that field workers can use it easily while working in remote areas and harsh environments. Group call in PTToC enables users to exchange information simultaneously with multiple users, and by this means all the group members are fully aware of the situation.

In summary, the rise in the usage off PTToC is due to the speed offered by 3G and 4G mobile networks and the introduction of smartphones. With the introduction of new applications for PTToC technology, it seems that PTToC communications will be an essential component of emerging LTE-based solutions.

To further know about implementation of VoLTE, Technologies, Challenges, and RCS for Public Service, you can join our  Voice over LTE (VoLTE) and RCS Certification Courses here.

Nokia Networks Advancing to LTE-A Carrier Aggregation Deployment


Nokia Networks is already globally known for its spectrum re-sharing, load balancing and traffic steering in different aspects. Now it is upgrading LTE-A technology globally that offers higher data rates to the subscribers and LTE operators.

Recently, in September 2015, the Nokia Networks have upgraded the Softbank’s commercial network by deploying LTE-A with faster data rates of up to 262.5 Mbps as claimed officially. The 1.4 times faster LTE-A technology has been facilitated with 3-band carrier aggregation on the commercial network.

By upgrading the LTE radio network to LTE Advanced Carrier Aggregation, the mobile network can now be benefitted with three component carriers besides the two aggregated bands. In carrier aggregation technology, 10 MHz spectrum sources are aggregated on the 900 MHz band as well as the 1800 MHz band. While, 15 MHz spectrum sources are aggregated on the 2100 MHz band. To derive the data rate even faster, a data highway of 35 MHz has been deployed in the network which offers about 262.5 Mbps downlink data rates to the subscribers.

The LTE-Advanced Carrier Aggregation technology evolves alongside the subscribers’ demands for higher data rates as well as the capability of their smartphones to support the band combinations of Carrier Aggregation. Today the user equipment are being built to aggregate up to three frequency bands, while some equipment have already been into the market which aggregate two frequency bands at a time. The new LTE-A software by Nokia Networks facilitates the subscribers to achieve the highest data rates that can be supported by their devices and smartphones. With this technology, any combination of the bands can be aggregated out of the three frequency bands.

So far we have discussed the advantages of the LTE-A Carrier Aggregation Technology for the users and subscribers. If we analyze the benefits of this technology from the operators’ point of view, we find out that the LTE operators will now able to drive the development of a wider range of smartphone ecosystem with the three frequency band aggregation technology.

Since SoftBank is considered as one of the top ten largest LTE Operators worldwide, this new frequency band combination will be widely installed in the markets around the globe. When the 900 MHz band for 2G is reframed to the 1800 MHz band for LTE, and the 2100 MHz band for 3G is reframed on the LTE band, the LTE operators get the advantage of higher data rates due to this carrier aggregation of three components.

The LTE-Advanced Carrier Aggregation technology deployment has opened new horizons in the communication technology and set a global example for LTE operators in achieving higher data rates for 4G.

To further know about LTE Network Planning, LTE-A Carrier Aggregation, Implementation, and Challenges you can join our  4G LTE Radio Network Planning and Optimization and 4G LTE-A Certification Courses here.

TETRA Radio Evolution Archive


TETRA Radio Evolution Path to 4G LTE

TETRA Radio evolution to 4G LTE is essential in order to enhance the mission critical emergency communication services. A framework for smooth transition of TETRA RADIO to LTE is shown below.

tetra radio evolution to LTE

For smooth transition of TETRA Radio to LTE, initially the critical voice and data messages will run in the narrowband TETRA network, while the high speed non-critical yet secured data will run in the commercial LTE broadband network. A technical architecture of TETRA Radio smooth transition to LTE is shown below:

TETRA Radio Evolution to TETRA 3 Broadband TETRA

Most recently, TETRA standardization bodies have identified user requirements for broadband mission critical data applications which include transfer of multimedia video and photo transfer, location data,  office applications, upload and download of operational information and online database enquiries. As a result, ETSI TC TETRA has initiated a new work item to expand the TETRA standard for transfer of broadband packet data which is scheduled until the end of 2016. Even the whole TETRA industry is extremely uncertain in the moment whether TETRA is already a legacy technology and will shortly be replaced by mission critical LTE.

tetra radio evolution training

UK & USA plan to replace TETRA with LTE until 2016 for Critical Communications & Public Safety

Within the next three years, LTE could replace the TETRA system that currently provides mission-critical communications for public-safety agencies and other government organizations in Great Britain, an official said yesterday.

Since 2005, mission-critical communications have been transmitted over the Airwave system—a privately owned TETRA network that covers 99% of the land mass and 98% of the population in Great Britain (England, Scotland and Wales). It serves “all three emergency services and other national users” that pay subscriptions fees, according to Gordon Shipley of the United Kingdom Home Office. Although the performance of the TETRA system is “very good,” it is “extremely expensive” for users, particularly when compared to the plummeting per-minute costs of commercial wireless air time, he said.

In addition, the contracts associated with the Airwave system are scheduled to expire from 2016 to 2020, so the UK Home Office is looking for alternatives, Shipley said.

“Because [the Airwave network is] a TETRA-based system, it’s narrowband data,” Shipley said during the session. “One of the things which has become clear is that the emergency services are now increasingly going broadband services, which can provide even higher speeds. And we need to provide a better, more reliable and secure service for broadband, as well as narrowband voice. So, my program’s responsibility is to find a replacement for critical voice, as well broadband data services, and to do so cost effectively.

“We think, in the UK, that 4G LTE promises significant benefits over the current service that we buy.”

UK officials will conduct a supplier conference next month to get input on the notion of having a public-safety LTE system operational in December 2016, with the entire system transitioned to the 4G technology by 2020, Shipley said.

This development could have an impact in the United States, which is trying to get 3GPP—the global standards body for LTE—to include public-safety requirements such as mission-critical voice in future revisions of LTE that can be implemented in the nationwide broadband network being built by FirstNet, according to Andrew Thiessen, who helps lead the standards effort for Public Safety Communications Research (PSCR), a unit of the U.S. Dept. of Commerce.

“I think it’s imperative that everyone in the audience understand that the United States isn’t the only country that’s actually looking forward to LTE,” Thiessen said during the session. “In many ways, the United Kingdom is actually working faster than FirstNet, looking at a 2016 date for mission-critical voice.”

Of course, one of the key requirements for public safety is mission-critical, push-to-talk voice. A draft set of requirements for push-to-talk over LTE has been distributed to officials in other countries, and the initial response has been positive, Thiessen said.

“We’re actually getting pretty close,” he said. “The comments that we’re getting back are more about clarification of what a particular sentence meant and less so about, ‘Well, we view things very differently.’ Public safety operates fairly similar globally, so push to talk is push to talk, whether it’s TETRA or P25 or whether it’s the United Kingdom or the United States—the expectations of the user community are very similar.”