5 Myths about 5G New Radio
2018-09-14 | 7 min read
With 5G New Radio (NR) Release 15 approved by the 3GPP (Third Generation Partnership Project) standards committee in June 2018, the race is on deliver on the IMT-2020 vision:
- In enhanced mobile broadband (eMBB), target peak data rate of 20 Gbps in the downlink and 10 Gbps in the uplink are specified, sufficient to support streaming of 4K or 8K UHD videos.
- In ultra-reliable low-latency communications (URLLC), < 1 ms latency is required to support demanding applications such as self-driving automobiles and mission-critical drones.
- In massive machine type communication (mMTC), support for up to 200,000 devices per square kilometer is necessary to support high-density IoT sensor networks.
How much of the 5G vision can be made real with 5G NR Release-15? 5G NR will have limited support for the different use cases at initial release. Let’s review my top 5 misconceptions about 5G NR Release-15.
Myth 1: 4G networks go obsolete with the introduction of 5G
False. 4G LTE is continuing to evolve and, in fact, will play a major role in the success of 5G. The expectation is that 5G NR is a totally new air interface that can operate alongside 4G LTE. The 5G RAN (Radio Access Network) will be able to operate with both 5G NR (gNB) and LTE (eNB) base stations. 5G NR can operate in non-standalone mode (NSA) where the UE requires a legacy eNB for control plane in order to support NR communication. Initial introductions of 5G will be in non-standalone mode. Standalone mode (SA), which was added to the spec in June 2018, is when the 5G network can operate independent of the 4G core network. What it comes down to is that 4G is not going away anytime soon. The expectation is that 4G and 5G will continue to work together with dual connectivity to deliver a diverse set of services.
Myth 2: All signals are treated equally
False. 5G NR introduces a flexible numerology to enable a wide range of frequencies and scheduling of diverse services that can be high throughput, low-latency, or even high latency for IoT applications. A scalable sub-carrier spacing enables scalable slot duration so that more slots can run in less time. To support future low-latency, mission-critical applications, a mini-slot is shorter in duration than a standard slot and can start at any time without waiting for the start of a slot boundary.
Myth 3: 5G NR is all about mmWave spectrum
False. While the use of mmWave spectrum will be critical to meeting the extreme data throughputs expected in 5G mobile broadband, frequency bands below 6 GHz will also be used for all three use cases: eMBB (enhanced mobile broadband), ULLRC (ultra reliable low latency communications), and mMTC (massive machine type communications). Sub-6 GHz spectrum used in 4G LTE is well understood and will be used for initial 5G releases around the world. 3.4 GHz to 3.8 GHz is being considered by about 20 countries where more contiguous spectrum can be found. Sub-6 GHz has some new challenges, but mmWave frequencies with the use of wider carrier bandwidths introduces a host of new issues not experienced by mobile operators in the past. There will be difficulties in achieving high-quality signals at mmWave frequencies.
Myth 4: 5G tests will be very similar 4G LTE tests
It depends. Designs using sub-6 GHz operating bands, possibly similar, but implementations at mmWave, most definitely not. Most sub-6 GHz tests are performed by physically connecting a coaxial cable from the device to the test system. If a device implements mmWave operating bands, however, components are smaller, and antennas are being integrated directly into RFICs resulting in no physical connection points, making it difficult, if not impossible, to make a cabled connection. Without a cabled connection, over-the-air (OTA) test methods are needed. Also, with the increased use of MIMO beam steering and beamforming in 5G NR, OTA is the preferred method for testing these technologies.
OTA measurements in R&D should include beam-pattern measurements, cross-polar measurements, and beam steering or null steering to understand performance. Conformance tests are still being defined. 3GPP recently approved a compact antenna test range (CATR) test method which uses a parabolic reflector system that enables far-field like measurements in a much shorter distance, providing an accurate, lower cost, compact alternative to the typical far-field test chambers.
Myth 5: 5G New Radio specifications are complete
False. 5G NR standards are still under development and will be rolled out over the next several years. ITU and 3GPP are using a phased approach to enable widespread commercialization by 2020. Phase 1 focuses on 4G LTE and 5G NR Release-15. 5G NR Release-15 is all about setting the foundation for enhanced mobile broadband (eMBB) and ultra-reliable and low latency communications (URLLC) use cases. Phase 2 will continue the evolution of 5G NR with optimization and add new use cases starting with 5G NR Release-16 by the end of 2019. It is expected that NR Release-15 is forward compatible with NR Release-16. In addition, the 3GPP continues to define enhancements to LTE-Advanced Pro in Release-15 and Release-16.
Many challenges ahead. With so much of 5G still being defined, you need to think differently about how you will test. 5G and 4G dual connectivity, flexible numerology, signal quality at mmWave frequencies, and OTA testing all require new thinking.
If you’re interested in learning more about 5G NR challenges, I suggest downloading the following white paper series: First Steps in 5G: Overcoming New Radio Device Challenges Series.