How Will the FCC Spectrum Decision Help Mobilize mmWave for 5G?
Last month, the Federal Communications Commission (FCC) voted to adopt the Spectrum Frontiers Proposal to allocate vast amounts of spectrum at frequency bands above 24GHz (known as millimeter wave or mmWave). As stated in the FCC fact sheet on its decision, "Building on a tried-and-true approach to spectrum policy that enabled the explosion of 4G (LTE), the Chairman's rules would set in motion the United States' rapid advancement to next-generation 5G networks and technologies."
The FCC decision to move forward with making mmWave spectrum available for 5G, in conjunction with other ongoing parallel FCC efforts to make more low-band and mid-band spectrum available as well, will enable rapid development and deployment of next-generation 5G technologies and services to bring 5G to fruition, we must get the most out of every bit of spectrum across a wide array of available spectrum regulatory paradigms (including licensed and shared) and spectrum bands -- from low bands below 1GHz, to mid bands from 1GHz to 6GHz, to high bands known as mmWave.
Advanced antenna techniques As implied by the name "millimeter wave," the small wavelengths at these higher frequencies enable the use of a much larger number of antenna elements in a relatively small form factor than is possible in lower bands. 5G will take advantage of these antennas to form narrow directional beams and send and receive more energy to overcome the propagation/path loss challenges. In addition, mmWave channel measurements and field testing have shown that the so-called non-line-of-sight paths (for example, reflections from nearby buildings) can generate very large energies that provide alternative paths when line-of-sight paths are blocked. To enable a good mobile broadband user experience with mmWave requires continuous intelligent beam searching and tracking algorithms to discover and switch to the dominant beam path. This dominant beam path will be constantly changing based on environment, mobility and a slew of other factors.
To showcase these technologies, Qualcomm Research has developed a 5G mmWave prototype system operating in the 28GHz band using wide bandwidths, capable of providing multi-gigabit per second connectivity. The prototype system showcases adaptive beam-forming and beam-tracking techniques that enable robust and sustained broadband communications even in non-line-of-sight environments and with device mobility. The system is already being utilized in 28GHz field testing today, and it is also flexibly designed to support testing, demonstrations and trials at additional mmWave spectrum bands, such as the 32GHz band being considered in Europe.
Spectrum sharing Beyond advanced antenna techniques, new effective spectrum sharing schemes will be critical to the success of 5G mmWave, which is particularly well suited to spectrum sharing schemes due its dense spatial reuse. The FCC decision adopts effective sharing schemes to ensure that diverse users -- including federal and non-federal, satellite and terrestrial and fixed and mobile -- can co-exist. Specifically, the FCC created a new Upper Microwave Flexible Use service in the 28GHz (27.5-28.35GHz), 37GHz (37-38.6GHz) and 39GHz (38.6-40GHz) bands, and expanded the current 57-64GHz unlicensed band to 71GHz. New technologies for spectrum sharing are being pioneered today with work on the Citizens Broadband Radio Service at 3.5GHz in the US, Licensed Shared Access (LSA) to access the under-utilized spectrum, such as spectrum for military radar, in a mutually beneficial way, as well as our work on making the best use of unlicensed spectrum with LTE-U, LAA and MulteFire.
Tight interworking with sub-6GHz 5G mmWave must also be designed for tight interworking with 5G deployed in sub-6GHz spectrum, as well as multi-connectivity with 4G LTE access, to further increase the robustness of the 5G mmWave design. Sub-6GHz spectrum bands remain critical for providing ubiquitous coverage and capacity to successfully support the wide range of 5G use cases.
Driving 5G standardization These innovative and impactful 5G designs for mobilizing mmWave are now being contributed to 3GPP to drive 5G New Radio (NR) standardization. It is the combination of these advancements in 5G technologies, along with standardization and regulatory efforts to identify and open up 5G spectrum, such as this FCC Spectrum Frontiers decision, that will help drive timely commercial network launches of 5G. To learn more about the technologies behind mobilizing mmWave, check out the recently published whitepaper Exploring the Potential of mmWave for 5G Mobile Access.
— Dean Brenner, SVP, Government Affairs, Qualcomm Inc. (Nasdaq: QCOM)