VoNR stands for Voice Over New Radio, which is a video voice technology operating under the 5G SA network infrastructure.
According to Wiki, ‘Voice over 5G New Radio’ is a 5G high-speed wireless communication standard for mobile phones and data terminals, including Internet of Things and wearable devices.
Before understanding VoNR in the 5G era, let’s review the history of mobile voice services.
In the 2G and 3G era, CS (Circuated Switched) technology is used for voice services, i.e. mobile phones need to establish a line in the network for exclusive use of resources before making calls. and it won’t be dropped until the call ends. This ancient technology has disadvantages such as resource consuming, complex network connection and low efficiency.
Entering the era of 4G all-IP, because there is only PS in the packet domain, traditional CS voice is no longer supported, two solutions CSFB and VoLTE are proposed to support voice service.
CSFB(CS FallBack) means that when the mobile phone initiates a voice call on the 4G network, it reverts from the LTE network to the 2/3G network, completing the voice call with the help of its CS circuit domain. 2/3G network, then back to 4G LTE when the call ends.
VoLTE or Voice over LTE is an LTE network that provides IP-based voice services directly through the introduction of IMS. VoLTE is also known as VoIP over 4G LTE network managed by IMS.
VoLTE “packages” voice services into IP data packets and transmits them like express packets without “proprietary resources”, greatly improving network efficiency. Furthermore, VoLTE offers unprecedented improvements in voice quality and reduced call setup time.
VoLTE applies AMR-WB (Adaptive Multi-rate-Wideband, Adaptive Multi-rate Wideband Coding) voice coding technology, which greatly improves the encoding speed compared to the 2G and 3G era, and increases the bandwidth. voice communication from 300Hz-3400 Hz to 50 Hz -7000 Hz, providing clearer sound quality and wider sound range, making the sound quality of mobile networks comparable to the experience of listening to the radio. When dialing, 3G network takes about 6-8 seconds to connect, while VoLTE only takes about 2-3 seconds to connect.
It can be seen that, regardless of the perspective of technical architecture or user experience, VoLTE is a revolutionary technological development in the history of voice service development of mobile networks.
Will 5G voice service be another leap forward like VoLTE? What does VoNR in the 5G era look like? What is VoNR, is it the optimal solution for 5G voice services?
To answer the above questions, it can first be stated that voice service in the 5G era will never be as revolutionary as VoLTE. In fact, the 5G system does not provide a separate technical solution for voice services, and its design goal is mainly to support the continued evolution of VoLTE.
IMS is the “brain” of VoLTE, and VoLTE is essentially an end-to-end VoIP connection technology controlled and managed by the IMS core network. Because IMS can implement end-to-end QoS management for voice service, the voice quality of VoLTE is much stronger than that of Internet VoIP.
Entering the 5G era, when 3GPP defined 5G in version R15 made it clear that 5G was still based on IMS for voice service delivery and determined that 5G implementation would minimize the impact on IMS design principles now available.
With the above principles, there are two main deployment options of 5G NSA and SA, 5G voice service provides three deployment solutions: VoLTE, EPS Fallback and VoNR.
In the NSA network, 5G NR is added to the existing 4G network as a capacity expansion, and the EPC uses the 4G core network core. 4G network is still the main control network, and 5G NR only supports data transmission with maximum effort.
Under such an architecture, voice service is still provided by the existing 4G IMS/VoLTE network with little or no change; voice calls can still be made seamlessly between VoLTE and 2G/3G CS networks via SRVCC; If the operator does not deploy IMS, it can still fall back to the 2G or 3G network to provide voice service through the Fallback CS.
In the SA network, the 5G network has its own 5GC core network, no longer relying on 4G as the control network, which means that 5G voice services can be transmitted end-to-end independently through 5G NR, 5GC and IMS , that is, VoNR (Voice over NR ,Voice over NR ) or Vo5G (Voice over 5GS, Voice over 5GS).
However, in the early stages of 5G SA deployment, since the 5G NR network has not yet completed the continuous wide coverage area, when the mobile phone goes out of the 5G NR coverage area, it will switch the ongoing VoNR voice over to the 5G NR network. VoLTE with better coverage, resulting in poor user experience. Therefore, the transformation solution – EPS Fallback – is introduced in the early stages of 5G deployment.
Similar to CS Fallback in 4G era, in EPS Fallback solution, 5G network does not provide PS voice service, when mobile phone tries to use voice service on 5G network, it will fall back to 4G network through via redirection or switching Provide VoLTE voice service and return to the 5G network after the call ends. During the call, because the phone has switched to the 4G network, the data service is also forced to switch to the 4G LTE line along with the voice service until the call ends.
According to this scheme, since voice call is initiated back to 4G network when setting up voice call on NR, voice call setup time will definitely increase. At the same time, data traffic is also transmitted over 4G LTE during the call and the data rate will be greatly reduced which will affect the user experience.
While Fallback for 4G will add a bit of call delay, VoLTE can provide faster call setup times than CS Fallback and this extra delay is tolerable. In fact, the biggest drawback of EPS Fallback is that in addition to reducing data rates, it also causes short-term interruption of voice connections due to switching back to 4G, which may be more noticeable to users than when making a delay call.
As mentioned above, VoNR is an end-to-end voice service provided by 5G NR, 5G Core and IMS. Strictly speaking, NR is just the radio access network part of the 5G network, while 5GS (5G System) includes 5G NR and 5G Core, so it is more accurate to call it VoNR Vo5G (Voice over 5GS Voice over 5GS). However, the VoNR that we often talk about and refer to is Vo5G.
Compared to EPS Fallback, the advantage of VoNR is obvious. First, the VoNR technology does not need to fallback to VoLTE and the call setup time is shorter; secondly, VoNR supports 5G voice and 5G data services simultaneously, which means we can both access high-speed 5G Internet while making calls.
In case when mobile phones move to 5G cell coverage area, VoNR voice quality will be poor or even degraded. To ensure voice call continuity, the ongoing VoNR call needs to be switched to 4G VoLTE. Therefore, similar to the SRVCC solution in the 4G era, the VoNR solution also supports smooth switching between VoNR and VoLTE through the Inter-RAT handover mechanism. (Inter-RAT handover)
With the advent of 5G Core, the 5G R15 standard does not define the connection standard between 5G Core and 3G Core and does not support voice call continuity between 5G and 3G CS, which means in networks that support R15 support using VoNR IMS /VoLTE is required to be able to maintain call continuity over 4G VoLTE if the phone moves out of 5G coverage during a call.
However, in R16 3GPP version, based on existing 4G to 3G handover standard, 5G SRVCC function is added, meaning voice can be transferred to 3G CS through 5G SRVCC technology.
From the perspective of user experience, although VoNR continues to adopt VoLTE architecture and cannot achieve the same revolutionary technological breakthroughs as VoLTE, VoNR has good voice call quality, latency, and low latency. low connectivity and 5G high-speed Internet access during calls.
For example, in theory, the MOS value of VoNR is 4.6 and the access delay is only from 1.5 to 2 seconds; VoLTE’s MOS value is about 4.1 and the access delay is 2 seconds; while the MOS value is 2/3G Voice CS is 3.7 , the access delay is as high as 6 seconds or more.
VoNR can also greatly improve the security of voice calls and the quality of video calls, and provide users with a better experience by fully integrating voice, video, touch, and voice. kinetic senses in the future.
For operators, network service providers, the benefits of VoNR technology are mainly evaluated through the following aspects:
One is that VoNR can accelerate the transition of old and inefficient traditional 2/3G CS voice services to 4G and 5G, thereby improving network efficiency, reducing network operation and maintenance costs, and regenerating. high quality low frequency resources.
Second, VoNR is beneficial for supporting new 5G applications. 5G applications use AR/VR technology, the holograms we talk about today that cannot be separated from real-time high-resolution audio and video calls. With VoNR, enhanced multimedia services can be provided to better support these new applications.
Third, VoNR brings a new source of income for service providers. Although the operators’ traditional 2C-oriented voice services are continuously affected by OTT voice. But voice service, as a basic communication service, is still a part of carriers’ revenue, and current 5G data plans are mostly tied to voice.
More importantly, before the era of digital transformation and smart connected things, voice and video services are expanding from people-to-people connections to the vast connectivity market between people and things. In the future, in the 5G 2B or 5G private network market, there will be a large number of situations that require high-quality, real-time audio and video communication, and high stability audio and video, also requires VoLTE based on IMS (slice)./VoNR and the viability assurance of ViLTE/ViNR.
No matter from the perspective of users or carriers, no matter from the perspective of improving current network efficiency or future business prospects, VoNR is a technology worth recommending. Since VoNR is designed on top of the evolution of 4G IMS and also relies on VoLTE for voice service continuity, it is for enterprises to introduce VoLTE first as a basic requirement.
Via: Vn-Z.vn