Analog Approximate-FFT 8/16-Beam Algorithms, Architectures and CMOS Circuits for 5G Beamforming MIMO Transceivers
Analog Approximate-FFT 8/16-Beam Algorithms, Architectures and CMOS Circuits for 5G Beamforming MIMO Transceivers
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DOI：
10.1109/jetcas.2018.2832177
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发表时间：
2018-05
影响因子：
4.6
通讯作者：
V. Ariyarathna;A. Madanayake;Xinyao Tang;D. Coelho;R. Cintra;L. Belostotski;S. Mandal;T. Rappaport
中科院分区：
文献类型：
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作者：
V. Ariyarathna;A. Madanayake;Xinyao Tang;D. Coelho;R. Cintra;L. Belostotski;S. Mandal;T. Rappaport
新兴的毫米波（mmW）无线系统需要波束成形和多输入多输出（MIMO）方法，以便减轻通信信道的路径损耗、障碍和衰减。尖锐的毫米波波束对于此目的至关重要，并且必须支持至少1 GHz的基带带宽以促进更高的系统容量。本文研究了一种基于空间傅里叶变换的基带多波束形成方法。近似计算技术被用来提出一个低复杂度的快速算法与稀疏因式分解，整齐地映射到整数$W/L$的CMOS电流镜的比率。因此，可以使用CMOS模拟集成电路来有效地实现所得到的近似快速傅里叶变换（FFT），以在发送和接收模式两者中生成多个并行的mmW波束。本文提出了8点和16点近似FFT算法，以及电路理论和65纳米CMOS实现的设计信息。在Cadence Spectre中对8点电路进行布局后仿真，可提供定义明确的mmW波束形状、2.7 GHz基带带宽、70 mW功耗和>42.2 dB的动态范围。初步的实验结果证实了8光束电路的基本功能。对16波束I/Q版本的原理图级分析显示，1 GHz带宽下的最差情况和平均旁瓣电平分别为−10.2 dB和−12.2 dB，1.5 GHz带宽下分别为−9.1 dB和−11.3 dB。所提出的多波束架构有可能降低电路面积和功耗要求，同时满足新兴5G基带系统的带宽要求。
Emerging millimeter-wave (mmW) wireless systems require beamforming and multiple-input multiple-output (MIMO) approaches in order to mitigate path loss, obstructions, and attenuation of the communication channel. Sharp mmW beams are essential for this purpose and must support baseband bandwidths of at least 1 GHz to facilitate higher system capacity. This paper explores a baseband multi-beamforming method based on the spatial Fourier transform. Approximate computing techniques are used to propose a low-complexity fast algorithm with sparse factorizations that neatly map to integer $W/L$ ratios in CMOS current mirrors. The resulting approximate fast Fourier transform (FFT) can thus be efficiently realized using CMOS analog integrated circuits to generate multiple, parallel mmW beams in both transmit and receive modes. The paper proposes both 8- and 16-point approximate-FFT algorithms together with circuit theory and design information for 65-nm CMOS implementations. Post-layout simulations of the 8-point circuit in Cadence Spectre provide well-defined mmW beam shapes, a baseband bandwidth of 2.7 GHz, a power consumption of 70 mW, and a dynamic range >42.2 dB. Preliminary experimental results confirm the basic functionality of the 8-beam circuit. Schematic-level analysis of the 16-beam I/Q version show worst-case and average side lobe levels of −10.2 dB and −12.2 dB at 1 GHz bandwidth, and −9.1 dB and −11.3 dB at 1.5 GHz bandwidth. The proposed multi-beam architectures have the potential to reduce circuit area and power requirements while meeting the bandwidth requirements of emerging 5G baseband systems.