QoS-Aware Energy Saving Based on Multi-Threshold Dynamic Buffer for FTTR Networks

doi:10.12142/ZTECOM.202504007

Abstract

Abstract:

As Fiber-to-the-Room (FTTR) networks proliferate, multi-device deployments pose significant energy consumption challenges. This paper proposes a Quality of Service (QoS)-aware energy-saving scheme based on a multi-threshold buffer energy saving (MBES) scheme to reduce consumption while ensuring energy QoS. MBES leverages the centralized control of the main fiber unit (MFU) and the wireless-state awareness of subordinate fiber units (SFUs) for synergistic fiber-wireless energy savings. The scheme assigns independent, dynamic buffer thresholds to service queues on SFUs, enabling low-latency reporting for high-priority traffic while accumulating low-priority data to extend sleep cycles. At the MFU, a coordinated scheduling algorithm accounts for Wi-Fi access delay and creates an adaptive closed-loop control by adjusting SFUs’ buffer thresholds based on end-to-end delay feedback. Simulation results show that, while satisfying strict latency requirements, MBES achieves a maximum energy saving of 17.75% compared with the no energy saving (NES) scheme and provides a superior trade-off between latency control and energy efficiency compared with the single-threshold buffer energy saving (SBES) scheme.

Key words: Fiber-to-the-Room, power consumption, energy consumption, energy saving

CAI Jinhan, ZAN Mingyuan, SHEN Gangxiang. QoS-Aware Energy Saving Based on Multi-Threshold Dynamic Buffer for FTTR Networks[J]. ZTE Communications, 2025, 23(4): 48-64.

Figures/Tables 14

Figure 1 FTTR network architecture

Figure 2 Status-report-based dynamic bandwidth allocation process

Figure 3 Functional modules and power consumption breakdown of the SFU

Figure 4 Process of the SFU’s multi-threshold wake-up mechanism

Table 1 Simulation scenario, traffic, and EDCA parameter settings

Scenario Settings
Number of SFUs	2/3/4/5	Number of Stations per SFU	2
Traffic Settings
VO data rate	30 Mbit/s	VI data rate	30 Mbit/s
BE data rate	30 Mbit/s	BK data rate	30 Mbit/s
Packet size	1 500 B	Traffic duration	1 s
EDCA Settings
Access category	CWmin	CWmax	AIFSN
VO	3	7	2
VI	7	15	3
BE	15	1 023	6
BK	15	1 023	9

Table 2. MFU bandwidth scheduling parameter settings

Table 3 Parameter settings for the power consumption model

Parameter	Value	Parameter	Value	Parameter	Value
$P b a s e$	1	$P T x$	1.2	$P R x$	0.8
$P R F_b a s e$	0.6	$P m a x$	6	$α D$	0.2
$D$	5 m	$σ$	1 dB	$G A$	3 dBi
$M$	5 GHz	$W k$ (5G)	15 dB	$j k$	0
$P L$ (5G)	23 dBm	$R m a x m$ (5G)	2 402 Mbit/s	$R S S I$	-40 dBm
$P M_m a x$	10	$α M_B a s e$	0.4	$α M_D y n a m i c$	0.6
$T u p o v e r h e a d$	$125 μ s$	$T d o w n o v e r h e a d$	$125 μ s$

Table 3 Parameter settings for the power consumption model

Parameter	Value	Parameter	Value	Parameter	Value
$P b a s e$	1	$P T x$	1.2	$P R x$	0.8
$P R F_b a s e$	0.6	$P m a x$	6	$α D$	0.2
$D$	5 m	$σ$	1 dB	$G A$	3 dBi
$M$	5 GHz	$W k$ (5G)	15 dB	$j k$	0
$P L$ (5G)	23 dBm	$R m a x m$ (5G)	2 402 Mbit/s	$R S S I$	-40 dBm
$P M_m a x$	10	$α M_B a s e$	0.4	$α M_D y n a m i c$	0.6
$T u p o v e r h e a d$	$125 μ s$	$T d o w n o v e r h e a d$	$125 μ s$

Table 4 Buffer threshold parameter settings

Parameter	VO	VI	BE	BK
Latency requirement/ms	2	10	30	50
Initial buffer threshold/kB	3	30	60	100
Step size (decrease/increase)/(kB/ms)	2/1	2/1	2/1	2/1
Consecutive cycle threshold (cycle)	10	5	5	5
Maximum buffer threshold/kB	100	200	500	1 000
Single threshold buffer/kB	196
Physical buffer constraint /MB	32

Figure 5 Average system latency under the NES, SBES, and MBES schemes (STA=2): (a) end-to-end latency of high-priority services, (b) end-to-end latency of low-priority services, (c) optical-side latency of high-priority services, and (d) optical-side latency of low-priority services

Figure 6 System energy consumption under the NES, SBES, and MBES schemes (STA=2): (a) FTTR system energy consumption and(b) average SFU energy consumption

Figure 7 System energy consumption with a 10 Gbit/s uplink rate under the NES, SBES, and MBES schemes (STA=2): (a) FTTR system energy consumption and (b) average SFU energy consumption

Figure 8 System latency under the NES, SBES, and MBES schemes (SFU=2): (a) end-to-end latency of high-priority services, (b) end-to-end latency of low-priority services, (c) optical-side latency of high-priority services, and (d) optical-side latency of low-priority services

Figure 9 System energy consumption under the NES, SBES, and MBES schemes (SFU=2): (a) FTTR system energy consumption and(b) average SFU energy consumption

Figure 10 System latency and energy consumption under dynamic and fixed buffer thresholds: (a) latency comparison and(b) energy consumption comparison

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