Major breakthrough on mmWave propagation and channel modeling
Understanding radio propagation in the mmWave frequency range is vital for the development of 5G. Ericsson Research experts, in partnership with European researchers in the mmMAGIC project, have performed extensive mmWave channel measurements and modeling for a multitude of scenarios. Let’s look at our key achievements.
Present cellular communications systems utilize frequencies below 6 GHz. The frequency range 24-86 GHz – which is subject for allocation within International Mobile Telecommunication 2020 (IMT-2020) spectrum at the World Radiocommunication Conference 2019 – is however mainly in the mmWave range. Compared with below 6 GHz, loss in radio signal due to absorption in materials or blockage by buildings, vegetation, vehicles, and humans is expected to be substantially different in the mmWave range. Moreover, important radio channel characteristics such as multi-path delay spread and directional spread have previously been poorly understood in the mmWave range.
To overcome this knowledge gap, the mmMAGIC project (co-funded by the European Commission’s H2020 program) has undertaken a major effort in the area of propagation research with extensive measurement campaigns performed over 2-80 GHz for a multitude of different indoor and outdoor scenarios. In addition, researchers have performed simulation campaigns in selected popular environments and frequencies to provide a large data set of propagation channels for the purpose of channel modelling. Overall, 54 single-frequency equivalent campaigns have been conducted. An overview of these measurements and simulations is depicted in figure below.
Overview of measurement (black) and simulation (blue) campaigns.
Requirements for channel measurements
The assessment of any frequency dependency over the measured range is key in the development of 5G mobile communications and spectrum allocation. To ensure comparability between channel measurements at different frequencies, a set of important requirements have been established:
- Equal measurement bandwidth
- Equal antenna pattern, either physical or synthesized
- Equal dynamic range for analysis both in delay and angle domains
- Equal angle resolution (for example, array size equal in terms of number of lambda)
- Same environment and same antenna locations
The measurement data in the mmMAGIC project has been thoroughly analyzed assuring that the above requirements were fulfilled.
Key results and contributions in channel modeling
Based on channel measurements and thorough analysis, the key characteristics of mmWave propagation can now be largely understood. All details are publicly available in the project’s final report Measurement Results and Final mmMAGIC Channel Models. The key results have, to a large extent, already been incorporated into propagation models in 3GPP and ITU-R, as listed below:
- Extensive high quality measurement data contributed to 3GPP 5G channel modeling.
- Measurements and modeling of building penetration loss used as substantial input to 3GPP and ITU-R models.
- A substantially improved blockage model adopted by ITU-R.
- Addition of ground reflection added to ITU-R IMT2020 channel model.
- Thorough statistical analysis (determining confidence ranges shown in the figure) of frequency dependency of delay spread and angle spread, with no significant frequency dependency observed, in contrast to the less thorough result of the 3GPP modelling effort.
Indoor measurement of angle spread in line of sight (LOS) and non-line of sight (NLOS) [paper].
Frequency dependence of RMS delay spread of the 3GPP and mmMAGIC channel models. The confidence ranges of the mmMAGIC model are indicated with dashed lines.
The mmMAGIC channel model structure and corresponding major contributions.
The mmMAGIC consortium comprises of 18 organizations in Europe (Samsung, Ericsson, Huawei, Nokia, Alcatel-Lucent, Intel, Orange, Telefonica, Keysight Technologies, Rhode & Schwarz, HHI, CEA-Leti, Imdea Networks, Bristol University, Chalmers University, TU Dresden, Qamcom, Aatlo University). For details on the mmWave radio interface design, please visit the project webpage.