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In distributed device-to-device (D2D) communications, no common reference time is available and the devices must employ distributed synchronization techniques. In this context, pulse-based synchronization, which can be implemented by distributed phase-locked loops is preferred due to its scalability. Several factors degrade the performance of pulse...
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Context 1
... in arbitrary fluctuations in the weighted average TO estimates ∆t j [ν] [24]. To eliminate this source of randomness in the set D ν,η j , we propose a method called alternating transceiver mode, which enables devices to determine their transceiver mode independently in a systematic manner. The underlying concept of the method is illustrated in Fig. 3. When a device first joins the network at the νth clock tick, it randomly initializes its transceiver mode, where the probability of being a transmitter, denoted as p tr ∈ (0, 1), is pre-determined and the same for all devices. If a device operates as a transmitter, it broadcasts its synchronization signal and then for the next clock ...
Context 2
... on the diagram in Fig. 3 and assuming that the probability of signal detection for a receiver is high, the devices will cluster themselves into TX and RX groups and alternate between them at each clock tick. We have observed this behavior in our simulations under representative conditions of operation for Long-Term Evolution (LTE) [27], as further discussed in ...
Context 3
... the bias estimate of D1, i.e., β 1 [ν + 3], is simplified accordingly from (16) and we assume a fixed step size, i.e., γ, for updating the bias estimate. Note that TO estimate at each device must decrease to zero before changing sign, consequently, we have sgn( In Fig. 13, we plot the maximum synchronization error (33) against a straight line with negative slope as given by (52). The results show a very close match between the two curves, thereby supporting our analysis. For comparison, we also plot the synchronization error with adaptive step ...
Citations
... As reported in [10], an universal pulse-based joint estimation algorithm of clock skew and offset in WSNs is introduced with the propagation delay estimated under a reference clock. In addition, typical pulse-based synchronization methods without reference clock are presented in [11][12][13]. The clock offset estimation methods are given in [11] and [12] with assuming the ideal condition that takes neither propagation delay nor clock skew into account. ...
... However, in practical systems, there will inevitably be propagation delay and clock skew, and they will have a crucial impact on the performance of clock synchronization. Recently, a timing advance synchronization technique is introduced in [13] considering the existence of propagation delay and clock skew, where the impact of propagation delay is eliminated by using a certain iterative method. However, the clock skew is not solved so that the loss of synchronization accuracy is inevitable. ...
... The main contributions of this article are summarized as follows: firstly, compared to pulse-based method in [13], the proposed method further solves the problem of clock skew estimation and achieves better accuracy; secondly, compared to timestamp-based method in [8], the proposed method employs the physical layer pulse to avoid the random delay. In addition, compared to synchronization algorithms with a reference clock, whether timestamp-based or pulse-based, the proposed method is more suitable for distributed networks and has more flexibility. ...
Clock synchronization is indispensable for numerous applications of wireless sensor networks (WSNs). When no common reference clock is available, the nodes must employ distributed synchronization techniques. This paper proposes, a distributed pulse‐based clock synchronisation approach, wherein the propagation delay is eliminated through signal ping‐pongs between neighbouring nodes. Such an approach can jointly estimate the clock skew and offset without requiring any reference clock. The whole synchronization process is completed at the physical (PHY) layer, effectively avoiding the random delay caused by packet queuing and retransmission. Simulation results show that the proposed approach can achieve higher synchronization accuracy compared with other existing methods.
... In [9], the authors provide a framework of DPLL algorithm and analyze its impact of propagation delay, multipath effect and single carrier frequency division multiple access on the performance. [10] proposes a halfduplex clock synchronization algorithm based on DPLL and uses an iterative method to estimate communication delay. The algorithm has high synchronization accuracy and good scalability, but the computational complexity is high and clock frequency skew is not considered. ...
... The authors confirm that the signature ensemble synchronization scheme is superior to the master-slave-based configuration, which motivates further investigations in collision-based synchronization in dense networks. In this context, [22,23] compensate the negative impact of the propagation delay and multipath propagation on the widely used distributed phase-locked loop (DPLL) based self-synchronization scheme suggested in [24]. Motivated by the half-duplex nature of the transmission scheme, [23] allows each SBS to self-determine its suitable mode of operation. ...
... In this context, [22,23] compensate the negative impact of the propagation delay and multipath propagation on the widely used distributed phase-locked loop (DPLL) based self-synchronization scheme suggested in [24]. Motivated by the half-duplex nature of the transmission scheme, [23] allows each SBS to self-determine its suitable mode of operation. Unlike master-slave-based time synchronization, distributed decision-making allows all nodes to play an essential role in achieving the network time synchronization. ...
To fulfill a higher data rate requirement in fifth-generation (5G) systems, mobile network operators are steering the access architecture toward ultradense network (UDN) deployments. However, the coexisting small cells and macrocells in UDN require highly accurate timing synchronization among the base stations. Traditional master–slave-based time synchronization techniques are not well suited in several new deployment scenarios of 5G like dense urban, urban canyon, etc., which do not easily access the global positioning system (GPS). Moreover, a good back-haul requirement and high signaling overhead limit the applicability of existing techniques in small cell deployment scenarios. Despite a large amount of work done in the area, an
efficient
timing synchronization technique for dense networks is not well addressed, which this work aims to investigate. By applying an efficient approach for collecting information from an enlarged neighborhood at a minimal signaling cost in our modified timing update process, we provide a
low-complexity
and
faster
GPS-independent timing synchronization solution for a dense network. Numerical investigations evaluate the impact of the graph topology and nodes number on the network synchronization speed. Finally, we prove that the proposed algorithm achieves asymptotic convergence with probability one.
