# Low-Complexity Synchronization Scheme with Low-Resolution ADCs
## 1 Introduction  
As the bandwidth and antenna configurations of next-generation (5G) wireless systems continue increasing, various services and applications in 5G networks are deployed in a single system to meet high-speed access requirements in multi-user and multi-machine environments [1]. Ultra-wideband (UWB) communications attracted considerable interest, targeting applications in high-speed data transfer wireless communication systems [2]. A major benefit of such systems is the achievement of high data rates, with low power consumption and low system implementation cost [3]. UWB is recently seen as an indoor short-range high-speed wireless communication [4] with a sampling frequency of megahertz (MHz) and gigahertz (GHz), and the technologies used in UWB systems are mainly divided into three categories: impulse radio (IR) [5, 6], multi-band orthogonal frequency division multiplexing (MB-OFDM) [7], and direct sequence spread spectrum (DSSS) [8]. Unfortunately, high-speed (e.g., more than 10 GHz) and high-resolution analog-to-digital converters (ADCs) arecostly and power-hungry. In particular, high-resolution ADCs with 10 GHz still have difficulties in manufacturing technology. Whether in UWB systems, millimeter wave systems [9], or massive multi-input-multi-output (MIMO) systems [10; 11], from the point of improving power consumption, using a receiver with low-resolution ADCs is a direct way of realizing high energy efficiency. One of the challenging issues for an orthogonal frequency division multiplexing (OFDM) system is its high peak-to-average power ratio (PAPR) [12]. This implies large fluctuations in signal power, ending up with increasing complexity of ADCs and digital-to-analog converters (DACs). Also, power amplifiers must work in a larger linear dynamic region. For the PAPR of single-carrier frequency division multiple access (SC-FDMA) signals, it was shown in Reference [13] that SC-FDMA signals indeed have lower PAPR compared to orthogonal frequency division multiple access (OFDMA). Based on Reference [13], the channel-dependent scheduling (CDS) scheme was proposed to reduce the power consumption and the PAPR of uplink SC-FDMA. The issue of subcarrier and power allocation in SC-FDMA was addressed in Reference [14]. The authors divided the problem into three stages and realized the optimal power allocation of subcarriers while reducing the complexity of the joint optimization process. In Reference [15], the authors analyzed the PAPR performance under \(\upmu\)-law Soft Reduction (\(\upmu\)LSR) and \(\upmu\)-law output subtracting cyclic prefix output (\(\upmu\)LaCP). Then, two new techniques for reducing PAPR were proposed. The proposed schemes could reduce PAPR with no bit error rate (BER) deterioration and keep the system low in complexity. Moreover, the two techniques can be added to any OFDM system. On the basis of Reference [15], the authors further studied the PAPR reduction technique in a turbo-coded OFDM system [16]. In order to reduce PAPR along with sustaining unchanged BER performance, the authors improved the \(\upmu\)LaCP technique [15] with the core idea called \"\(\upmu\)-law output subtracting inverse fast Fourier transform (IFFT) output\". Compared with the above research work, some people began focusing on how to reduce the complexity and power consumption of the systems from a hardware perspective. Therefore, in recent years, low-resolution quantization techniques received increasing attention. Modern communication transceiver designs leverage [PERSON]'s law for low-cost implementation (e.g., for today's cellular systems), by using digital signal processing (DSP) to perform sophisticated functionalities such as synchronization, equalization, demodulation, and decoding. The central assumption in such designs is that analog signals can be faithfully represented in the digital domain, typically using ADCs with 8-12 bits of precision.