The LTE technology used in many of our smartphones for voice/video calls or video streaming is 4G. In an era where 4G LTE is already an integral necessity in our lives, what is 5G? How will it change our lives? What can we expect from it?

Since the days of analog technology in the late 1970s, the mobile communication has been continuously evolving with each new generation enabling new services. In the early 2010s, when 4G LTE technologies were just hot off the press and commercial 4G services were about to take off, many organizations in academia and industry initiated research on next-generation breakthrough technologies with Samsung Electronics leading the pack with its own 5G research initiative in 2011.

In line with such research movement across the globe, ITU (International Telecommunication Union) held a World Radio Communication Assembly in October 2015 where they designated the official name of 5G as 'International Mobile Telecommunication (IMT)-2020' and published the technical vision of 5G. 5G mobile communication has three key components: (1) enhanced Mobile Broadband (eMBB); (2) Ultra Reliable & Low Latency Communications (URLLC); and (3) Massive Machine-Type Communications (mMTC).

According to ITU's definition, eMBB can be characterized by a peak download speed of 20 Gbps and a user-experienced download speed of at least 100 Mbps. For example, downloading a single 15 GB movie takes at least four minutes for 4G LTE (at the peak data rate of 500 Mbps), but only six seconds for 5G at the peak data rate of 20 Gbps. Some of the new applications that are expected to be serviced over 5G are HD videos, virtual reality (VR), and augmented reality (AR).

For support of URLLC, 5G is able to provide 99.999% reliability and 1 ms latency (1 ms is 1/1000th of a second). For example, in a 4G network, when an obstacle appears in front of a self-driving car moving at 100 km/h, a stop signal can be received only after the car has driven more than 1 m. The same distance can be reduced to 2.8 cm in a 5G network, drastically reducing the risk of vehicular accidents.

Besides the big jump in data rates and latency, 5G is expected to play a critical role as a platform for providing connectivity to various forms of IoT devices in homes and industries. 5G aims to enable connections for 1 million devices within an area of 1km2. Such connectivity on a massive scale, i.e., mMTC, is essential in order to accommodate an exponentially increasing number of IoT devices such as smart devices and sensors.

To accommodate the requirements as described above, a new spectrum range was assigned for 5G, which is broader and higher than 4G. The spectrum range includes not only low frequency bands below 6GHz (including 3.5 GHz), which are similar to the conventional 4G spectrum, but also the ultra-high frequency millimeter wave (mmWave) bands such as 28 GHz and 39 GHz which were never previously used for the purpose of mobile communications.

Following the commercialization of 5G technologies, both academia and industry are initiating research activities to shape the next-generation communication system, namely 6G. Considering the general trend of successive generations of communication systems introducing new services with more stringent requirements, it is reasonable to expect 6G to satisfy unprecedented requirements and expectations that 5G cannot meet.

We expect that 6G will provide ultimate experience for all through hyper-connectivity involving humans and everything. In our 6G white paper, we aim to provide a comprehensive overview of various aspects including technical and societal trends, services, requirements, and candidate technologies.

XDD (Cross Division Duplex) is one of the key technologies that Samsung is proposing as part of Rel-18 NR (5G-Advanced) to address the coverage issue observed during the initial phase of 5G deployment. XDD provides improved coverage, capacity, and latency compared to conventional TDD. Instead of relying solely on orthogonal time resources for DL-UL separation as in TDD, XDD allows simultaneous DL-UL operation by using non-overlapping frequency resources within a carrier bandwidth.

This white paper provides a high level description of XDD concept, benefits, and implementation challenges. First, an overview of XDD including a comparison with conventional TDD and FDD is provided. Next, the implementation challenges of XDD especially at the base station to handle self-interference mitigation is provided. Furthermore, several features that we consider critical in realizing XDD in actual deployment scenarios are provided along with some performance results. Finally, Samsung’s view on XDD for the next phase of 5G (5G-Advanced) is provided.

Expanding the boundaries of what is possible in spectrum has been our passion at Samsung.

6G is facing a formidable challenge to be significantly greater than evolved 5G. To do this will require new spectrum from sub-1 GHz to sub-THz, in addition to the continued reuse of existing spectrum in the low, mid and high bands.

As a follow-up of our 6G white paper published in July 2020, we in this white paper explore how to enable 6G to be realized around 2030 from a spectrum’s perspective.