In OFDM-based mobile networks, uplink synchronization is essential in order for an eNB (evolved Node Base station) to handle a variety of interference issues. To guarantee uplink synchronization control, the HARQ (Hyb...
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ISBN:
(纸本)9781467359382
In OFDM-based mobile networks, uplink synchronization is essential in order for an eNB (evolved Node Base station) to handle a variety of interference issues. To guarantee uplink synchronization control, the HARQ (Hybrid Automatic Repeat-reQuest) mechanism is applied into the process of its TAC (Timing Advance Command) transmission in current standards. But HARQ conflicts with the TAC scheduling mechanism in nature, because TAC control information is typically scheduled for transmission at the end of a synchronization period in order to save signaling overhead by reducing TAT (Time Alignment Timer) restart frequency. To handle the conflict between the extra HARQ retransmission delay and TAC scheduling mechanism, we propose a novel TO (Time Offset)-TAC solution that can remove the side effects from TAC information delivery caused by the extra delay of HARQ retransmission. We conduct system-level simulation experiments to evaluate our proposal's performance gain. Results demonstrate that our solution can avoid losing synchronization due to its TAT expiration, at a slight penalty of signaling overhead. This study is the first effort at addressing how to guarantee uplink time alignment in the control layer, which is the basis for suppressing interference from “time-staggered symbols” among multiple paths.
In this letter,a WDM-OFDM-PON architecture using LDPC code is brought up to increase transmission range and system *** optical line terminal(OLT),LDPCcoded OFDM signal at 1.-Gb/s is transmitted as *** each optical net...
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ISBN:
(纸本)9781467356985
In this letter,a WDM-OFDM-PON architecture using LDPC code is brought up to increase transmission range and system *** optical line terminal(OLT),LDPCcoded OFDM signal at 1.-Gb/s is transmitted as *** each optical network unit(ONU),the optical OFDM signal is demodulated with direct detection,and on-off keying date at 2.5Gb/s is returned as *** results show that the transmission distance could exceed 20-km with negligible penalty.
For the first time, bidirectional multi-band multi-gigabit wireless-over-fiber transmission at 60-GHz mm-wave band has been accomplished with centrally supplied LO service. It does not require mm-wave LO devices in ea...
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ISBN:
(纸本)9781557529626
For the first time, bidirectional multi-band multi-gigabit wireless-over-fiber transmission at 60-GHz mm-wave band has been accomplished with centrally supplied LO service. It does not require mm-wave LO devices in each base stations and mobile terminals.
To save signaling overhead, Serai-Persistent Scheduling (SPS) is the standard for delivering Voice-over-IP (VoIP) in OFDM-based mobile networks. But uncompressed or variable-size compressed VoIP packets are problemati...
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To save signaling overhead, Serai-Persistent Scheduling (SPS) is the standard for delivering Voice-over-IP (VoIP) in OFDM-based mobile networks. But uncompressed or variable-size compressed VoIP packets are problematic for SPS because they spill over the assigned semi-persistent resource whenever the ROHC (Robust Header Compression) mechanism is in an initialization or reset period, propagating system latency and accumulating unnecessary signaling overhead. In response, we propose a Self-Adaptive Scheduling (SAS) algorithm, where dynamic scheduling is used as an adaptive mechanism to assist in scheduling oversized packets, triggered by buffer information already known to the system, without requiring dedicated signaling. To analyze the performance of our proposal in theory, we created a novel theoretical model to describe VoIP traffic considering the uncompressed voice {1.. This is, to our best knowledge, the first effort to model the effect of uncompressed packets on VoIP performance in mobile networks from the system-level point of view. Theoretical analysis and simulation experiments validate our proposal, demonstrating its ability to enhance the VoIP user experience for a minor signaling overhead cost.
We demonstrate a passively mode-locked Erbium-doped fibre laser by using CVD fabricated graphene as both saturated absorber and dispersion compensator to achieve a 1.-nJ energy pulse with 303-fs width, resulting in a ...
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ISBN:
(纸本)9781849197595
We demonstrate a passively mode-locked Erbium-doped fibre laser by using CVD fabricated graphene as both saturated absorber and dispersion compensator to achieve a 1.-nJ energy pulse with 303-fs width, resulting in a 40-kW peak power, which is the highest value for graphene-based Erbium-doped passively mode-locked all-fibre laser.
We experimentally demonstrate subband switching with a frequency spacing of 1.-GHz in a Tb/s elastic optical network based on optical single-carrier frequency-division-multiplexing (SCFDM) superchannel. .9; 201. IEEE.
An energy efficient spectrum allocation algorithm in bandwidth-variable optical switching {1. is proposed, in which the modulation format of subcarriers is selected in a dynamic way according to the real-time tra...
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optical OFDM superchannel has been proposed for high-speed optical transmission system, which consists of multiple individual-modulated OFDM subbands. We experimentally demonstrate OFDM subband switching functionality...
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Three ONU auto-discovery schemes are proposed to reestablish connections between ONUs and OLT in network failure restoration for OFDMA-PONs. Simulation is conducted to compare the performances of these schemes. .9;...
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We proposed a gain-saturated RSOA and TOF based spectral red-shifted, directly-modulated tunable fiber ring laser as upstream laser source to suppress the reflection-induced crosstalk in a single-fiber bidirectional m...
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