7.1.1 Standardization gaps for the IMT-2020 high-level architecture
The gaps included in this clause were extracted from the output of the high-level architecture gap analysis work included in Appendix I.
Various bandwidth/data-rates demands
Priority: High
Description: The current network architecture is not appropriate to support various bandwidth demands, from ultra-high to extremely low, required for IMT-2020 and beyond. Enhancement of the network architecture should be studied to make IMT-2020 network more flexible and resilient with enhanced capabilities including the upgrades to session or bearer management, more efficient multicast methods, distributed function deployment, network slicing, and efficient codecs.
Related work: 3GPP, SG13
Complex connectivity model
Priority: High
Description: Local offloading can be used to support efficient traffic distribution. However, local offloading requires a separate local mobile GW in existing IMT networks, which also brings up the need to support multiple APN connectivity in user devices or initiate APN switching, which may result in service disruption of on-going sessions and operational complexities.
The network architecture for IMT-2020 should be studied to eliminate the need for separate local mobile specific gateways, additional APN and associated signalling.
Related work: 3GPP, SG13
Application-aware and distributed network architecture
Priority: High
Description: The heavily centralized architecture of existing IMT networks is should be changed to cope with the explosion of mobile data traffic. In IMT-2020 networks, therefore, gateways to an IMT-2020 core network can be flexibly located closer to the cell sites, which will bring a significant reduction on back haul and core network traffic by enabling placing content servers closer to mobile devices and also be beneficial to the latency of the services.
The IMT-2020 core network, therefore, is envisioned to be a distributed network being composed of the multiple distributed gateways. The architectural changes expected from the distributed network, including the point-to-point access architecture between a UE and a service network in existing IMT network, should be studied.
Related work: 3GPP, SG13
Signalling complexity in massive MTC
Priority: High
Description: The IMT-2020 network should address architectural issues coming from the massive number of MTC devices. The traffic generated by a very large number of connected devices typically will be a relatively low volume of non-delay-sensitive data; however, the traffic is characterized as intermittent short burst traffic. The main problem in supporting the intermittent short burst traffic is that traffic has to go through the full signalling procedure, which causes the waste of battery life, spectrum and network capacity. The enhancement of current monolithic bearer management and the accompanied signalling in IMT-2020 network should be studied to cope with the issues coming from the increase of terminals.
Related work: 3GPP, SG13
Increasing service availability
Priority: High
Note: from second call, confirmation to be confirmed. (via email)
Description: IMT-2020 networks should offer several ways to increase service availability by using the ability to replicate content and service functions and the use of forwarding functions for short and long term caching. In addition, delay-tolerant networking aspects, such as cache-and-forward, are very useful in the last mile where the content objects can be opportunistically pushed to or pulled by the end user based on its wireless conditions. The IMT-2020 network architecture should study methods to increase service and content availability.
Related work: IETF, SG13
Signalling to reduce end-to-end complexity
Priority: High
Description: There are various signalling procedures that contribute to the end-to-end connectivity establishment involving all network components such as the radio interface, the front haul/back haul and the mobile core network. Besides the transport delay through the network components, signalling which is basically accompanied in the beginning of each new session or transmission may have more serious impacts on total end-to-end latency. For IMT-2020 and beyond, more efficient signalling protocols or systems should be studied to cope with the limitations on the existing mobile systems.
Related work:
End-to-end network latency model
Priority: High
Description: Latency studies carried out on many IMT-Advanced deployed networks demonstrate that the 3GPP specification provides adequate guidelines, while actual IMT-Advanced network performance varies due to many variables and adjacent ecosystems. Similarly, a network latency model and an end-to-end latency budget for services should be studied so that it provides optimal performance for many diverse applications in IMT-2020 networks.
Related work: 3GPP, SG13
Mobile network optimized softwarization architecture
Priority: High
Description: The softwarization, has been initially designed for wired networks and it may not be optimized for mobile networks. The mobile network optimized softwarization should be studied considering the best use of existing features to overcome the performance issues which may arise in some of SDN solutions.
Related work: SG13
Data plane programmability
Priority: Medium
Description: The requirements of the data plane in an IMT-2020 network will vary depending on the service characteristics of new emerging services such as ICN. In-network data processing and service provisioning are the capabilities to cope with the diverse requirements of the data plane. However, the capabilities have not studied from mobile network perspective. The capabilities to support easier provisioning of new emerging services in IMT-2020 architecture should be studied.
Description: Discussions on QoS requirements of current IMT networks mostly focus on QoS at the RAN. An end-to-end (i.e. from a user device to another corresponding user device) QoS framework should be considered in the design of IMT-2020 network architecture.
Related work: SG12, SG13
Energy efficiency
Priority: High
Description: Energy efficiency should be considered in the beginning of the design of new IMT-2020 network architecture. While only a subset of total functions in IMT-2020 networks can be virtualized, the function virtualization and its dynamic management of virtualized functions are expected to contribute to the significant saving of energy. Energy efficiency should be defined first and then the measurement method also should be studied for IMT-2020 network. In addition, energy efficiency from life cycle management point of view should be studied.
Related work: SG5, ISO 14000 Series
Enhancement of privacy and security
Priority: High
Description: IMT-2020 networks should have the capabilities of determining and providing the level of privacy and security required of user devices and application services. Therefore, the security and privacy should be well considered in the network architecture design.
Related work: 3GPP, SG13, SG17
Enhancement identity management
Priority: High
Description: As IMT-2020 networks also aim to realize features of future network architectures and enabling services, the goal of identity management and associated security and privacy requirements should go beyond device identity to also include service, content, or other principles. The major functionalities may include identifier (ID) assignment, name translation, ID certification, name resolution, and related key distribution management. This is particularly important when these IDs are administered by third parties which are open to service/control/forwarding functions in the IMT-2020 network, in which case the requirements of the stake-holders have to be taken into account.
Related work: SG13 Y.2720, SG17, JCA-IdM, ISO/IEC JTC1 SC27
Multi-RAT connectivity
Priority: High
Description: Different radio interfaces have been defined by many different standardization organizations, which leads to complex and coarse-level of interworking in existing IMT networks. The signalling on different radio access networks is independent, resulting in inevitable duplications in signalling for attachment, authentication, and mobility in each radio access networks. Although traffic steering and the selection of best access technology in existing IMT networks is considered, more flexible and optimized multi-RAT interworking architecture should be studied, which may also affect the design of IMT-2020 network architecture. The multi-connectivity through the multiple available radio access networks improves the robustness of the network as well as the throughput performance.
Related work: 3GPP, SG13
Fixed mobile convergence
Priority: High
Description: Fixed access networks3 should be considered as an access network of IMT-2020 to interwork with other radio access networks. A converged access-agnostic core (i.e., where identity, mobility, security, etc. are decoupled from the access technology), which integrates fixed and mobile core, is envisioned as a direction of IMT-2020. Therefore, the IMT-2020 network architecture should be studied to support true fixed and mobile convergence ensuring a seamless user experience within the fixed and mobile domains.
Related work: 3GPP, SG13
Flexible mobility
Priority: High
Description: It is expected that mobility requirements for user devices will vary depending on the device and/or application types. Many user devices are stationary, e.g., smart meters and CPE, even in mobile networks while fast handover is a key feature of most mobile devices and some applications may address the mobility by setting up a new connection automatically with the help of buffering. The signalling procedure in existing IMT networks is heavy and not optimized for some emerging new services such as IoT. An enhanced mobility architecture should be studied to support “context-aware mobility” considering device types, application characteristics, etc. as the context for the mobility.
Description: As the IMT-2020 core network is envisioned to be a flat distributed network, which is composed of the multiple distributed gateways to cope with traffic explosion and latency requirements of applications, mobility management should be studied aligning with those architectural changes.
Related work: 3GPP, SG13
End-to-end network management in a multi-domain environment
Priority: High
Description: Multiple network management protocols in different network domains make it difficult to support unified network operations over multiple network domains. A unified end-to-end network management should be considered to ensure compatibility and flexibility for the operation and management of an IMT-2020 network.
Related work: SG13
OAM protocols
Priority: High
Description: OAM protocols are not standardized in some parts of IMT networks such as the front haul network. Standard OAM protocols should be studied for fault management and performance management between network equipment that may be commonly used across the IMT-2020 network.
