Synchronization Requirements for 5G: An Overview of Standards and Specifications for Cellular Networks

Lin, Jia-Chin

doi:10.1109/mvt.2018.2813339

Cited by 40 publications

(23 citation statements)

References 12 publications

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“…For example, for inter-site carrier aggregation (CA), coordinated multi-point (CoMP) [15], [16], ranging-based localization [17], time-domain inter-cell interference coordination (ICIC) [18] and distributed multiple-input multiple-output (MIMO) [19]. Also, RFS is required between any pair of time division duplex (TDD) cells transmitting on the same frequency band with overlapping coverage areas in order to avoid interference between their downlink (DL) and uplink (UL) time slots [15], [16]. Each RFS use case has its accuracy requirement, although not necessarily standardized.…”

Section: Introductionmentioning

confidence: 99%

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Testbed Evaluation of Distributed Radio Timing Alignment Over Ethernet Fronthaul Networks

Freire

Almeida²,

Medeiros

et al. 2020

IEEE Access

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This work investigates a mechanism for alignment of the timing on which spatially distributed and cooperative radio units transmit in radio-frequency (RF) when served over a packet-based fronthaul. It analyzes the problem by considering the imperfect clock synchronization of the radio units and the packet delay variation that fronthaul packets are subject to. Following the analysis, this paper proposes an implementation architecture for distributed RF transmission timing alignment based on synchronized triggering among radio units and centralized processing units. Throughout this discussion, special attention is given to the scheme's impact on the overall achievable fronthaul latency. Subsequently, this work discusses both hardware and software aspects of a prototype that was developed based on field-programmable gate arrays (FPGAs). In the end, it presents results obtained on an Ethernet fronthaul testbed where the referred FPGA-based prototypes implement radio units that are synchronized using the IEEE 1588 precision time protocol or by pulse-per-second references. Results validate the functionality of the proposed architecture and illustrate various relevant choices concerning system parameters. INDEX TERMS 5G, clock synchronization, Ethernet, fronthaul, precision time protocol.

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Section: Introductionmentioning

confidence: 99%

“…For instance, inter-site CA requires a relative time alignment error (TAE) below 260 ns [20]. In contrast, TDD over LTE small cells requires the TAE to be less than 3 µs [21], a requirement that dates from Universal Mobile Telecommunications System (UMTS) [16] and continues for 5G-NR [22].…”

Section: Introductionmentioning

confidence: 99%

Testbed Evaluation of Distributed Radio Timing Alignment Over Ethernet Fronthaul Networks

Freire

Almeida²,

Medeiros

et al. 2020

IEEE Access

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“…where c i denotes the chip-values of the m-sequence having output values of {+1, −1} respectively, since SS communication systems usually employ binary spreading sequences having chip values of {+1, −1}. In this contribution we assume that the m-sequence generator outputs duo-binary {+1, −1} symbols, 3 representing a logical zero by +1, while the product operation is denoted by (•). In the scenario of our iterative calculation-based acquisition method of Fig.…”

Section: A M-sequence Generatormentioning

confidence: 99%

“…The popularity of notepads, laptops, smart phones, gaming consoles, smart televisions and Personal Digital Assistants (PDAs) 1 has dramatically increased the tele-traffic [1], [2]. Efficient use of the transmit bandwidth plays a pivotal role in multi-media-centric environments [2][3][4]. Pseudo Noise (PN) sequence acquisition is the initial synchronization procedure of Spread-Spectrum (SS) communication systems [5][6][7][8].…”

mentioning

confidence: 99%

Primitive Polynomials for Iterative Recursive Soft Sequential Acquisition of Concatenated Sequences

et al. 2019

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An iterative initial sequence acquisition technique is proposed for the pseudo-noise signal derived from a pair of m-sequences used for generating the concatenated sequence, which relies on the soft-in-soft-out detection to improve the acquisition performance. This recursive soft sequential estimation technique has a linearly increasing complexity with the number of chips in the concatenated sequence. Receiving as few as S consecutive chips of a (2 S − 1)-chip sequence is sufficient for the local concatenatedsequence generator of the receiver to synchronize. Hence, this initial synchronization technique is eminently suitable for long m-sequences and concatenated sequences. Another key result is the comparison of m-sequences and concatenated sequences regarding the acquisition time. It is also observed that loworder primitive polynomials (PPs) achieve better performances than higher-order polynomials for both the m-sequences and concatenated sequences. When considering PPs having a higher number of taps, the exploitation of concatenated sequences is capable of achieving in excess of 3-dB signal-to-noise ratio gains over m-sequences.

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“…New Radio (5G NR) and the 5G Special Interest Group (5G SIG), all of which are based on orthogonal frequency division multiplexing (OFDM) [9]- [11]. Although mmWave communication has great potential for high data rate transmission, its characteristics differ significantly from those of conventional wireless technologies.…”

Section: Introductionmentioning

confidence: 99%

Pilot Sequence Design for mmWave Cellular Systems With Relay Stations in the Presence of Blockage

2020

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Due to short wavelength and weak diffraction ability, millimeter-wave (mmWave) signals are highly susceptible to blockage, which results in significant degradation in received signal power. As a possible solution for overcoming the blockage problem in millimeter-wave communication systems, the deployment of a relay station (RS) has been considered in recent years. In this paper, we discuss the problems to be considered in a relay-assisted mmWave cellular system based on orthogonal frequency division multiplexing. We describe a frame structure and a pilot-based training method to achieve efficient RS selection during blockage. In addition, a method designed to overcome the inter-symbol interference problem caused by different symbol time offsets of pilot signals received from adjacent RSs in the relayassisted mmWave cellular system is discussed. Then, we propose two different types of pilot sequences that allow a mobile station to distinguish among the pilot sources in multi-cell multi-relay environments: pilot signals based on the Zadoff-Chu sequence (PS1) and pilot signals based on the m-sequence (PS2). The correlation property of PS2 is derived and compared with that of PS1 and another sequence (Gold sequence). Simulations are performed using a blockage model to verify the properties, constraints, and advantages and disadvantages of the proposed pilot sequences in RS-assisted mmWave cellular systems. INDEX TERMS Blockage, cellular system, mmWave, pilot sequence design, relay.

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Synchronization Requirements for 5G: An Overview of Standards and Specifications for Cellular Networks

Cited by 40 publications

References 12 publications

Testbed Evaluation of Distributed Radio Timing Alignment Over Ethernet Fronthaul Networks

Testbed Evaluation of Distributed Radio Timing Alignment Over Ethernet Fronthaul Networks

Primitive Polynomials for Iterative Recursive Soft Sequential Acquisition of Concatenated Sequences

Pilot Sequence Design for mmWave Cellular Systems With Relay Stations in the Presence of Blockage

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