The Study Item on Licensed Assisted Access (RP-141646) introduced for the first time the notion of cellular-based access to unlicensed spectrum as a complementary tool for operators to augment their service offering.
For IMT systems, existing and new spectrum licensed for exclusive use by IMT technologies will remain fundamentally critical for providing seamless coverage, achieving the highest spectral efficiency, and ensuring the highest reliability of cellular networks through careful planning and deployment of high-quality network equipment and devices. All of these cannot be achieved by unlicensed spectrum which can never match the qualities of the licensed regime.
A lot of progress has occurred since then with the introduction of the LAA and eLAA features.
As the cellular industry enters its next phase of evolution with the study of a wider bandwidth waveform under the NR project, it is also time to incorporate those lessons into the evolution of the LAA feature. We call this “NR-based access to unlicensed spectrum”.
NR-based unlicensed access, with underlying unlicensed band CCs with wider bandwidth (e.g., 80 or 100MHz), will also reduce the implementation complexity for both eNB and UE, compared to carriers of smaller bandwidth, when moving to address larger amount of spectrum, something that we consider inevitable for those scenarios where multi-Gbps data rates need to be achieved.
In line with NR development and in order to maximize the applicability of NR-based unlicensed access, we consider beneficial studying solutions applicable to sub6 and above6 unlicensed bands (e.g., 5GHz, 37GHz, 60GHz). In the same vein, the study should look into scenarios and solutions where NR-LAA is anchored to a legacy LTE carrier by dual-connectivity (DC) similar to the NSA mode of regular NR operation, as well as CA based aggregation with a 5G NR anchor. Furthermore, it is beneficial to consider standalone operation of NR in unlicensed spectrum at an early stage and the study should address this.
As already considered in RP-141646 in some regions in the world, unlicensed technologies need to abide to certain regulations, e.g. Listen-Before-Talk (LBT). Fair coexistence between cellular operations and other technologies such as Wi-Fi, in its different versions, as well as between cellular operators themselves, is necessary. Even in countries without LBT, regulatory requirements exist to attempt to minimize interference with other users of the unlicensed spectrum. However, it is not enough to minimize interference simply for regulatory aspects. It is thus essential to ensure that a NR-based unlicensed access wideband system operates as a “good neighbour” towards all forms of legacy systems.
Therefore, the present document proposes a study to determine a single global solution for NR-based access to unlicensed spectrum, to be compatible with the NR concepts.
许可辅助接入技术最早因运营商为了提供更多服务而开始研究。而LAA技术的发展在一定程度上使得辅助接入技术向前推进。因此在NR项目下对于更大带宽的研究时候要将LAA的一些特点、经验和教训和NR相结合。从而有了NR-based access to unlicensed spectrum。