Low-resolution analog-to-digital converters (ADCs) in massive multi-user (MU) multiple-input multiple-output (MIMO) wireless systems can significantly reduce the power, cost, and interconnect data rates of infrastructure basestations. Thus, recent research on the theory and algorithm sides has extensively focused on such architectures, but with idealistic quantization models. However, real-world ADCs do not behave like ideal quantizers, and are affected by fabrication mismatches. We analyze the impact of capacitor-array mismatches in successive approximation register (SAR) ADCs, which are widely used in wireless systems. We use Bussgang's decomposition to model the effects of such mismatches, and we analyze their impact on the performance of a single ADC. We then simulate a massive MU-MIMO system to demonstrate that capacitor mismatches should not be ignored, even in basestations that use low-resolution SAR ADCs.
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Space-Constrained Mixed-ADC Massive MIMO
The uplink performance of a mixed analog-to-digital converter (ADC) massive multiple-input multiple-output (MIMO) architecture with a space-constrained array at the base station (BS) is analyzed. We investigate the effect of spatial correlation and mutual coupling on the spectral efficiency (SE) of the system. First, we analyze to what extent adding a small number of high-resolution ADCs can impact the channel estimation accuracy. Then, we derive a closed-form approximation for the SE. Our analysis demonstrates how a space constraint on a uniform linear array (ULA) can affect the design of a massive MIMO system with low-resolution ADCs. It is shown that by equally spacing a small number of high-resolution ADCs over the array, one can dramatically reduce the performance gap between a system with all low-resolution and all high-resolution ADCs.
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- Award ID(s):
- 1703635
- PAR ID:
- 10155024
- Date Published:
- Journal Name:
- Proc. IEEE 20th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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