High throughputs on existing LTE Mobile Network through ENDC
There is a significant growth in mobile traffic as the number of devices and diversity of services requires the mobile networks to provide high quality and high throughput services. This post will give you a clear understanding of how to achieve high throughputs by using ENDC (E-UTRA New Radio Dual Connectivity) and will address the advantages of using dual connectivity over earlier heterogeneous Networks. We will also see how a UE in dual connectivity enjoys more throughputs later in this post.
The high user throughput requirements can be achieved by means of Heterogeneous` Networks (HetNets). The HetNets architecture is composed of macro and microcells. One macrocell involves more than one small cell and therefore has bigger coverage compared to the small cell. The small cells in this architecture are acting as hotspot areas increasing capacity and help to dispose of some user plane data from the macro cell. The disadvantage of such a deployment is that the needed number of small cells is higher which significantly increases also the number of mobility procedures like cell reselections and handovers which may result in mobility-related issues. In order to fix the mobility-related issues concerning the HetNets, the DC (Dual Connectivity) technology has been standardized in 3GPP Release 15.
Now we need to move further ahead towards upgrading our networks to 5G NR so that we can provide higher data rates and better system reliability. NR stands for New Radio that uses 5G specifications for higher data rates and better system reliability.
E-UTRA New Radio-Dual Connectivity (ENDC) is a 3GPP release 15 feature introduced to support New Radio 5G data with existing LTE core and radio networks and without introducing 5G core network. Such type of network is Multi-RAT Network (Multiple Radio Access Technology Network).
ENDC can be a useful feature for Heterogeneous networks (HetNets) wherein LTE provides reliable coverage and NR can be used for improving data rates. This will enrich the user experience more towards 5G throughputs. Also, ENDC ensures better system reliability by reducing service interruptions due to higher propagation loss in mmWave or non-line of sight situations in Massive MIMO (Beam Forming).
Dual Connectivity (Intra LTE) and ENDC
Dual Connectivity is not a new concept. Earlier, according to Release 12 of 3GPP, DC can be achieved for Intra LTE case when a User Equipment (UE) which is configured in DC can be connected at the same time to two Evolved NodeBs (eNodeBs): a Master eNodeB and a Secondary eNodeB via X2 interface.
When we talk about ENDC we have A User Equipment (UE3 Refer to picture below) that can be connected at the same time to two NodeBs: a Master eNodeB and a Secondary gNodeB (Next Generation NodeB), which act on different carriers and are connected by X2 interface.
A Typical ENDC Scenario
Master eNodeB interconnected with two Secondary gNodeBs via X2 links and three UEs. UE 1 and UE 2 are connected to Master eNodeB and Secondary gNodeB2, respectively, while the UE-3 is in ENDC with the SecondarygNodeB1 and Master eNodeB. Therefore, the throughput of UE-3 may be increased because radio resources from SecondarygNodeB1 and Master eNodeB are utilized by this UE.
We will have a detailed look into the system architecture and procedures of ENDC on control and user plane level for NSA (Non-Standalone) and SA (Standalone) operation Modes in our further articles.
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