User-Centric Spectrum Integration: Optimizing Spectrum Efficiency and Enhancing User Experience

At the beginning of 2024, the representative technology of 5G-A, three component carrier (3CC) aggregation, was first deployed at scale in China. ZTE, in collaboration with domestic operators and industry partners, achieved a peak downlink speed exceeding 5.4 Gbps in multiple field test environments across Zhejiang, Shanghai, and other regions, laying a solid foundation for 5G-A commercialization. To meet the increasing speed demands of applications such as extended reality (XR) and ultra-high-definition (UHD) video, ZTE and domestic operators achieved a new downlink speed record of 9 Gbps. This milestone was accomplished through multi-carrier transmission combining FR1 100 MHz and FR2 800 MHz spectrum, utilizing commercial chips. Currently, over 100,000 3CC-enabled cells have been deployed across major regions in China, covering key areas such as scenic spots, central business districts (CBDs), universities, shopping malls, high-speed railways, subways, and so on.

While downlink speed continues to set new records, the widespread adoption of services like UHD live streaming has significantly increased uplink capacity demands. However, terminal limitations have rendered uplink speeds a bottleneck in further enhancing user experience. ZTE’s multi-carrier integration solution overcomes this bottleneck by employing uplink multi-carrier aggregation, uplink Tx switching time-division transmission technology and a flexible frame structure configuration. In April 2024, ZTE achieved an uplink peak speed of 1.2 Gbps in a field test in Beijing. This not only significantly improved users’ uplink experience but also demonstrated the enormous potential of new technologies in enhancing network uplink transmission efficiency. The solution provides strong technical support for a wide range of application scenarios, including cloud computing, big data, IoT, telemedicine, and UHD video uploads.

While existing multi-carrier technology ensures high-speed service experiences through aggregated carrier transmission, the independent scheduling of aggregated carriers limits flexibility and increases overhead as the number of carriers grows. Moreover, diverse combinations of carriers and transmission modes require an intelligent spectrum integration solution to maximize spectrum efficiency and ensure smooth user experiences. To address these challenges, ZTE has introduced a user-centric spectrum integration solution to further optimize spectrum efficiency and improve user experience.

Spectrum Pooling to Enhance Efficiency

With the re-farming of 2G/3G/4G spectrum, the release of new spectrum, and deeper network integration among operators, 5G spectrum resources have become increasingly abundant, spanning from low-band 700 MHz/800 MHz/900 MHz to ultra-high-band 26 GHz/28 GHz, with carrier bandwidths ranging from 10 MHz to 400 MHz. The aggregation of more spectrum provides a solid foundation for improving data rates, but as the number of aggregated carriers increases, overhead from independent transmission of common carrier information becomes more prominent. Redundant control information and imbalances in control channel quality across carriers also become significant issues, highlighting the need to simplify the use of spectrum and optimize the existing multi-carrier strategy.

ZTE’s user-centric spectrum integration solution introduces spectrum pooling technology, which enables the sharing of common and control channels among carriers within the same spectrum pool, thus reducing overhead and enhancing scheduling flexibility. Specifically, the solution employs a single downlink control information (Single DCI)-based multi-carrier joint scheduling mechanism, which reduces redundant overhead through the sharing of control channels and also addresses control channel imbalances across carriers, enhancing scheduling flexibility. The introduction of synchronization signal block (SSB)-less technology for multi-carrier scenarios minimizes the overhead associated with the repetitive transmission of common channels (such as SSB/SIB) by sharing these channels within the spectrum pool (Fig. 1). These innovations significantly enhance spectrum utilization and improve the user experience by 10% to 30%.

Intelligent Carrier Aggregation to Enhance User Experience

As carrier aggregation becomes more widely deployed, multi-carrier operation is becoming the primary mode for users. The traditional approach of selecting the best single carrier for users needs to evovle to meet the growing demand for optimal aggregation and higher speeds in multi-carrier scenarios. ZTE’s user-centric spectrum integration solution introduces intelligent carrier combination and transmission mode optimization based on built-in intelligence, ensuring optimal user experience and maximizing cell spectral efficiency.

This solution leverages the base station’s built-in capabilities to identify user and service types accurately. By considering UE capabilities, carrier configurations, carrier loads, and channel conditions, the system employs multi-dimensional data modeling to predict the potential carrier combinations and transmission modes for each user across different cells. Based on these predictions, the system selects the optimal carrier combination and transmission mode for each user, ensuring a guaranteed and consistent experience.

As networks evolve from 5G to 5G-A and eventually 6G, numerous new services, scenarios, applications, and ecosystems will emerge. At the same time, with the release of existing spectrum and the discovery of new spectrum, the diversity of spectrum resources will become increasingly evident. This will require continuous optimization of multi-carrier solutions to meet the growing user demands.

ZTE’s user-centric spectrum integration solution breaks through the traditional constraints in spectrum resource allocation and scheduling. By dynamically orchestrating high-, medium-, and low-frequency resources based on user and service requirements, carrier capabilities, and channel quality, it transcends the limitations of flexibility in existing multi-band network. Through cross-layer decoupling, cross-band decoupling, and uplink/downlink decoupling, the solution unlocks spectrum flexibility, improves spectrum efficiency, and meets the diverse needs of users in the evolving 5G and 6G landscape.