Tradeoffs for 60 GHz Communication
Ahmad Bahai, Wim Van Thillo1, Jimmy Nsenga2 and Sofie Pollin
National Semiconductor, Interuniversity Micro-Electronics Center (IMEC) and European Commission
We study how to maximize the signal-to-noise ratio (SNR) in wideband multi-antenna receivers where the cost and power consumption of the analog-to-digital converters (ADCs) is dominant.
First, we focus on analog versus digital receive beamforming, where analog beamforming allows us to reduce the number of ADCs used. We investigate optimal clustering schemes to assign antennas to the ADCs, when the number of ADCs is lower than the number of antennas.
Next, we study how to maximize the SNR in receivers that employ time-interleaved ADCs. Current wideband receivers interleave a fixed number of slower ADCs into one fast ADC and assign this latter to one antenna according to an antenna selection algorithm. However, this does not always guarantee an optimal tradeoff between thermal noise and quantization noise. This results in an overall SNR that is lower than what could be obtained with the same number of ADCs, assigned in a more optimal way. Therefore, we propose to adjust the number of slower ADCs assigned to a certain fast, interleaved ADC dynamically, according to the SNR of every individual antenna. Our proposed algorithm can be implemented at the expense of a very limited hardware complexity increase.
The SNR gain of our new scheme can exceed 7 dB, depending on channel conditions and ADC specifications.
1Interuniversity Micro-electronics Center
2Interuniversity Micro-electronics Center