A series of recent papers,

- Channel Estimation and Performance Analysis of One-Bit Massive MIMO Systems
- One-bit massive MIMO: Channel estimation and high-order modulations,
- Performance of the Wideband Massive Uplink MIMO with One-Bit ADCs,

suggest the use of 1-bit ADCs in Massive MIMO base station receivers. Important studies of a concept, that offers great potential for cost saving and simplification of transceiver hardware.

Granted, much lower resolution will be sufficient in Massive MIMO than in conventional MIMO, but will one bit be sufficient? These papers indicate that the price to pay is not insignificant: the number of antennas may have to be doubled in some cases. Also, while the use of symbol-sampled models as in these studies may give correct order-of-magnitude estimates of capacity, much future work appears to remain to understand the effects of digital channelization/prefiltering and sampling rate conversion if 1-bit frontends are going to be used.

It is interesting that, for one-bit ADCs, it can become more difficult to detect the symbols when there is too little noise, interuser interference and intersymbol interference—the amplitude information is then lost.

Probably the presence of noise/interference acts as dithering, resulting in some form of stochastic resonance.

Does that mean increasing transmit power does not help increasing the rate, while increasing number of antennas helps?

You are right, capacity in a one-bit ADC MIMO channel does not behave in the same way as the capacity in the common AWGN channel, especially at at high SNR. For example, the capacity does not grow without bound when transmit power is increased but it grows linearly in the number of receiver antennas at high SNR. Capacity is analysed in this paper:

Mo, Jianhua, and Robert W. Heath. “Capacity analysis of one-bit quantized MIMO systems with transmitter channel state information.” IEEE Transactions on Signal Processing 63.20 (2015): 5498-5512.