A novel feed‐forward segmented digital automatic gain control algorithm for long‐term evolution digital radio‐over‐fibre systems

Wang, Jie; Hu, Xin; Guan, Enyi; Li, Tongyun; Ding, Zegang; Yao, Yao

doi:10.1049/iet-com.2017.0128

Cited by 7 publications

(5 citation statements)

References 16 publications

(19 reference statements)

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“…2, the DRoF architecture is composed of three components: a) a CU connected with mobile services in forms of the digital baseband signal, RF signal or digitised RF signal generated by MNOs, creating a signal source pool which contains BBUs, remote radio heads (RRHs) and CPRI/digital equipment; b) a fronthaul optical link connecting the CU with the distributed remote units (RUs); and c) multiple RUs for wireless coverage. In this system, centralised RF services are digitised and compressed to a lower bit rate as proposed by Li et al [27] and a DAGC module which controls the gain of the system is added to enhance the RF dynamic range before the ADC and data compression stages [28]. Novel gain estimation and rescaling algorithms are designed to optimise the system performance with lossy compression.…”

Section: Theory and System Proposal A System Architecturementioning

confidence: 99%

Novel Digital Radio Over Fiber (DRoF) System With Data Compression for Neutral-Host Fronthaul Applications

Chen

et al. 2020

IEEE Access

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Digital radio-over-fibre transmission has been studied extensively as a way of providing seamless last-mile wireless connectivity by carrying digitised radio frequency (RF) services over broadband optical infrastructures. With the growing demand on wireless capacity and the number of wireless services, a key challenge is the enormous scale of the digital data generated after the digitisation process. In turn, this leads to optical links needing to have very large capacity and hence, high capital expenditure (CAPEX). In this paper, we firstly present and then experimentally demonstrate a multiservice DRoF system for a neutral-host fronthaul link where both forward and reverse links use data compression, multiband multiplexing and synchronisation algorithms. The effect of a novel digital automatic gain control (DAGC) is comprehensively analysed to show an improved RF dynamic range alongside bit rate reduction. In this case, the system allows all cellular services from the three Chinese mobile network operators (MNOs) to be converged onto a single fiber infrastructure. We successfully demonstrate 14 wireless channels over a 10Gbps 20km optical link for indoor and outdoor wireless coverage, showing a minimum error value magnitude (EVM) of <8% and >60dB RF dynamic range. It is believed that the technology provides an ideal solution for last-mile wireless coverage in 5G and beyond. INDEX TERMS Digital radio over fiber, neutral host, cloud radio access network (C-RAN), multiband multiplexing, automatic gain control, 4G, 5G, fronthaul.

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Section: Theory and System Proposal A System Architecturementioning

confidence: 99%

Novel Digital Radio Over Fiber (DRoF) System With Data Compression for Neutral-Host Fronthaul Applications

Chen

et al. 2020

IEEE Access

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“…where in step (I) we use (8). We can conclude that SINR j (ξ * ) decreases with n. The settling time of the AGC should be as short as possible to increase SINR j (ξ * ).…”

Section: A the Behavior Of Sinr J (ξ * ) As A Function Of Nmentioning

confidence: 99%

“…Each category has its own advantages and disadvantages. The gain of the VGA can be converged in one step [8], [9]. The one step scheme shortens the settling time of the AGC.…”

Section: Introductionmentioning

confidence: 99%

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Analysis and Mitigation of ICI Due to Gain Adjustment in OFDM Systems

2019

IEEE Access

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Automatic gain control (AGC) is widely adopted in orthogonal frequency division multiplexing (OFDM) systems to compensate the significant variation of the received signal. In OFDM systems, the duration of the cyclic prefix (CP) is usually equal to the delay spread of the channel to minimize the system overhead. The inter-symbol interference (ISI) between consecutive OFDM symbols spreads over a large portion of the CP. The CP contaminated by the ISI should not be used to estimate the received power. If the duration of the remaining CP is shorter than the settling time of the AGC, then the gain adjustment will be carried out within the useful portion of the OFDM symbol. The subcarrier orthogonality is lost and the system performance is degraded by the resulting inter-carrier interference (ICI). In this paper, we propose a simple and efficient scheme to mitigate the ICI. The proposed scheme can be easily implemented in actual systems because of its low computational complexity. The simulation results show that the proposed scheme can increase the signal-to-interference-plus-noise ratio significantly compared to the traditional scheme.INDEX TERMS Automatic gain control, inter-carrier interference, inter-symbol interference, orthogonal frequency division multiplexing.

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“…In [19], a fast convergence two-stage AGC algorithm is proposed for a bluetooth low energy (BLE) compliant radio, while the gain tuning step is limited as the algorithm feeds the control signal to the analog chip. A feed-forward AGC algorithm proposed in [20], [21] focuses on making the most of ADC quantisation bits and maintaining stable peek-to-average ration (PAR). However, the accuracy and the stability of the system need to improve due to its open-loop structure.…”

Section: Introductionmentioning

confidence: 99%

Fast-Settling Two-Stage Automatic Gain Control for Multi-Service Fibre-Wireless Fronthaul Systems

et al. 2020

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With the development of fast digitiser and digital signal processing techniques, wide-band digital radio-over-fiber (DRoF) based wireless fronthaul systems have been extensively studied as a way of offering multi-service wireless coverage. With data compression, the high digital data rate caused by digitisation can be reduced so as to minimise the infrastructure cost for last-mile cellular coverage. However, data compression always comes with the cost of a lower input power dynamic range. To overcome the issue, this paper proposes a novel fast-settling two-stage automatic gain control (FSS-AGC) algorithm, in which gain adjustment is carried out by a multi-threshold decision mechanism with a fast-settling time (within 2µ s), high stability and great accuracy. By introducing a novel gain control mechanism which simultaneously adjusts the gain in the digital and RF domains, the loss of dynamic range after compression is compensated. This algorithm is applied and demonstrated in a DRoF based digital distributed antenna system (DDAS) which supports all current cellular services from 3 Chinese mobile network operators (MNOs). The demonstration shows over 73dB dynamic range, with 40dB improvement compared with conventional links. Its promising properties and excellent performance enable its potential application in next-generation converged networks for Internet of things (IoT) and 5G services.INDEX TERMS Automatic gain control, digital radio over fibre, settling time, dynamic range, gain control, 4G, 5G.

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A novel feed‐forward segmented digital automatic gain control algorithm for long‐term evolution digital radio‐over‐fibre systems

Cited by 7 publications

References 16 publications

Novel Digital Radio Over Fiber (DRoF) System With Data Compression for Neutral-Host Fronthaul Applications

Novel Digital Radio Over Fiber (DRoF) System With Data Compression for Neutral-Host Fronthaul Applications

Analysis and Mitigation of ICI Due to Gain Adjustment in OFDM Systems

Fast-Settling Two-Stage Automatic Gain Control for Multi-Service Fibre-Wireless Fronthaul Systems

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