[Warm-up before class] Several typical test questions in the future 5G era predicted by "Pokemon GO"

Pokémon GO has earned $470 million in 82 days since it was released in the App Store in July, and has been the top mobile game for several consecutive years. Although there are no exact figures on how much data the game consumes, most online sources believe that a person will consume at least 20 MB of mobile data per hour while playing the game.

If you happen to be a Pokemon Go player, then you must be concerned about the following questions:

The above problems have already appeared in the existing network, and will be difficult to avoid in the next generation of mobile communication (5G) networks in the future.

From this specific example, it is not difficult to understand the reasons and background for ITU to define 5G KPI and three typical application scenarios: hotspot high capacity, low power consumption and large connection, low latency and high reliability .

How to achieve faster access and faster communication with the server is essentially a question of improving user experience rate and system capacity, which is really a headache. Mobile communications have been exploring new physical layer technologies in all possible aspects, such as new waveforms, new modulation, new multiple access, etc.; MIMO multi-channel technology with spatial division multiplexing, and even considering the use of centimeter-wave and millimeter-wave frequency bands with larger bandwidth.

Let's talk about MIMO technology first. 3GPP Rl13 has defined 3D MIMO (not strictly speaking, it can be considered as the early form of Massive MIMO). Antenna technology has evolved from linear arrays in the 3G and 4G eras to planar arrays, and energy concentration is achieved through beamforming technology. This is extremely beneficial for operators to improve spectrum utilization. In addition, since LTE is adopted in the first phase, the terminal does not need to be changed, so the policy changes required for implementation are small, which has potential huge benefits for operators' business models. At the IWPC meeting this spring, representatives of China Mobile clearly stated that the 3D MIMO plan has been implemented. The industry expects that pre-commercial use will not be far away. Back to the topic of testing, the testing of 3D MIMO base stations is a new topic. How should traditional conduction testing be used when the number of antenna channels has increased by dozens of times? How should the OTA testing method, which is currently being studied and is very popular, be used? These problems are all realistic problems that are in front of us.

Let's talk about the development of high-frequency bands for mobile access networks, which has been discussed many times internationally. The definition of high-frequency bands generally refers to bands above 6 GHz. There are still many problems and difficulties in using high-frequency bands for mobile communications, especially millimeter wave bands (above 30 GHz).

First, the research on channel propagation models is still insufficient. We know much more about the channel propagation characteristics of the frequency band below 6GHz than the high frequency band. The channel propagation model affects fundamental issues such as product technical parameter design and network design. Research on it is crucial.

Then there is the question of communication performance, with a few examples highlighting the technical challenges involved, including random access, tracking, fading and blocking, and transceiver front-end design. Random access and tracking alone are daunting: Where do you point the antenna in the first place? How do you keep it pointed in the right direction? How do you manage direct and directional handoffs? All of these issues are under intensive study.

Back to the issue of testing, how to use the maximum flexibility of commercial off-the-shelf equipment to build a test bed that can flexibly configure various modules of high-frequency band communications, not only covering all RF bands from 3Hz to 110GHz, physical layer RF indicator tests of high-frequency bands, but also able to flexibly build a complete transceiver system, thereby verifying performance indicators such as system throughput. This testing requirement is very important for R&D personnel.

Several typical test issues in the future 5G era predicted by "Pokemon GO" include not only the test issues mentioned above, but in fact these are only a small part. Comprehensive testing of new components, parts, subsystems, channel environments, core networks, network architectures, etc. that make up the products are being studied in depth.

Keysight Technologies will organize senior 5G technical consultants to hold a series of special online lectures on several typical 5G test issues mentioned above. Each lecture will arrange a senior technical consultant in the relevant sub-field to introduce and discuss 1~2 5G test issues and methods with the audience.

In the first issue, we invited Li Feng, a senior technical consultant of Keysight Technologies, to discuss with the participating guests on several aspects such as the testing of millimeter wave broadband communications and several core testing issues of 3D-MIMO base stations. Welcome to participate, please stay tuned!

▲ Click on the picture above to watch the online exchange meeting on 5G key technology measurement