Massive MIMO in Mobile Environments

An impressive experiment, recently reported by colleagues at Univ. of Lund and Univ. of Bristol, shows TDD (reciprocity-based) Massive MIMO multiplexing to mobile terminals:

The interesting part starts at 2:48, with the terminals onboard cars. While it has been contested whether Massive MIMO can work in mobility (because of channel aging) this experiment confirms that it does — as predicted by theory for a long time. In fact, at 3.7 GHz carrier and with a slot length of 0.5 ms, the maximum permitted mobility (assuming a two-ray model with Nyquist sampling, and a factor-of-two design margin) is over 140 km/h. So the experiment is probably still not close to the physical limits.

7 thoughts on “Massive MIMO in Mobile Environments”

  1. [LinkedIn] Great news! My congratulations. We did similar test in February 2016. Maybe the main difference was that eNB operating in LTE TDD with 10MHz bandwidth with T_SRS = 5ms, and UE was Huawei Mate 7. For QPSK there was no problem, but for higher MCS indexes some losses. Do you check QPSK only? And all time all users occupied all band (20MHz) – 10 layers were used at least ? What is difference in downlink performance for mobility test vs. static scenario ?

  2. Hi
    I agree with the applicability of massive MIMO for high mobility, and your claim.
    However, regarding the measurement, I guess I read in some of their papers, that the highest speed that the university laws allowed them to test in the parking lot was something around 60km/h.
    Apart from under 5Ghz massive MIMO, if I’m not wrong, I guess millimeter massive MIMO would be more challenging due to a higher carrier frequency.

    1. Yes, mobility at mmWaves is more challenging. The channel may have a lot more structure, such that parametric channel estimation (e.g. angles-of-arrival) can be used, however, the rate of change of the channel is 30 times higher at 60 GHz than at 2 GHz carrier, and that issue has to be dealt with.

Leave a Reply

Your e-mail address will not be published. Required fields are marked *