Hence, I think your colleagues are having single-user transmission with massive beamforming in mind.

By spatially multiplexing, say, 8 users the overall spectral efficiency will rather be in the range of 24-48 bps/Hz.

]]>Sorry for being two months late to this thread, hopefully still open for questions… I’m debating this subject with colleagues, some of whom expect the overall spectral efficiency of a c-band mMIMO sector to be in the 3-6 bps/Hz range, which seems a very long way below what I’m hearing from vendors (and of course the Bristol results). They claim this is due to “real world” adjustments to expected performance, but that seems like a big adjustment. Can such conflicting levels of SE performance be explained? Perhaps currently available mMIMO equipment doesn’t implement digital beamforming, and hence no effective MU capability? What is the expectation of equipment evolution with respect to support for more effective spatial multiplexing – over the next 5 yeats for instance?

Many thanks

]]>You can find many of these things in Section 4 of my book Massive MIMO Networks, which you can download here: https://massivemimobook.com/wp/

]]>https://arxiv.org/pdf/1112.3810.pdf

https://arxiv.org/pdf/1403.6150.pdf

http://dx.doi.org/10.1109/TVT.2015.2436896

https://arxiv.org/pdf/1505.01181

https://arxiv.org/pdf/1401.4907v4.pdf

The good news is that Massive MIMO can achieve both high SE and EE, since both of these goals are achieved by multiplexing of many UEs, which share the energy costs and achieve a high sum SE. I believe that this is a topic we will return to on the blog.

]]>https://arxiv.org/pdf/1505.03682.pdf

https://arxiv.org/pdf/1509.02633.pdf

https://www.metis2020.com/wp-content/uploads/publications/IEEE_ICC2014_Guo_etal_UplinkPowerControl.pdf

Regarding uplink versus downlink, there is not absolute answer to that question, because there can be substantial transmit power difference between the uplink and downlink. Traditionally, the downlink uses higher power and thereby achieves higher SE. If the total transmit power is the same, then the uplink SE can be larger since the base station has direct access to the channel estimates and can thus decode the signals more accurately.

]]>For any given scenario (carrier frequency, Doppler spread, etc.), you can compute an approximate coherence time and coherence bandwidth, multiply them together and then you have the number of channel uses per coherence block.

]]>Actually, it could be interesting to discuss the same issues for moving users with Doppler spread 10-20 Hz at least.

]]>However, if we want to achieve high spectral efficiency per user, at the cost of lower sum spectral efficiency, we might want to have M/K>10.

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