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Optical Fiber Technology
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High-priority first dynamic wavelength and bandwidth allocation algorithm
in TWDM-PON
Lincong Zhang
a
, Jifeng Qi
a
, Kefeng Wei
b,c
, Wenbo Zhang
a,
⁎
, Yongxin Feng
a
, Weigang Hou
a
a
School of Information Science and Engineering, Shenyang Ligong University, Shenyang 110159, China
b
School of Computer Science and Engineering, Northeastern University, Shenyang 110819, China
c
Shen Kan Engineering and Technology Corporation, MCC., Shenyang 110169, China
ARTICLE INFO
Keywords:
TWDM-PON
Wavelength selection
Dynamic bandwidth allocation
T-CONT
ABSTRACT
Time and wavelength division multiplexing passive optical network (TWDM-PON) is the mainstream scheme of
the next generation access network, and it possesses a number of unique characteristics such as high-bandwidth,
long-distance data transmission, and connecting lots of users. As the difference among user traffic demands
increases, in order to effectively decrease the network delay and improve resource utilization, a high-priority
first dynamic wavelength and bandwidth allocation (HF-DWBA) algorithm in TWDM-PON system is proposed in
this study. According to the service-level agreement (SLA), in order to determine the priority of an optical
network unit (ONU), the proposed algorithm ensures the high-level ONU tra ffic distribution in terms of wave-
length assignment and bandwidth allocation, and it can execute five types of transmission containers (T-CONTs)
as well as four kinds of bandwidth allocation strategies. The results of simulation show that in comparison with
traditional algorithms, the proposed HF-DWBA algorithm can effectively reduce end-to-end time delay and
improve bandwidth utilization ratio, while making fairness among different types of bandwidth allocation
strategies.
1. Introduction
In order to meet a growing demand for high-bandwidth and traffic
perceived by users, a number of new high-bandwidth services have
been developed (e.g., network disk and cloud computing), possessing
some challenges to network access control. Traditional optical access
networks [1,2], such as Ethernet passive optical network (EPON) and
gigabit passive optical network (GPON), have not still fully satisfied the
users’ demands. Thus, full service access network (FSAN) commenced
to operate on the basis of next generation-passive optical network (NG-
PON), in which some requirements in 2011, indicating the time of
beyond 10 Gbps is coming [3,4]. In 2012, some studies reported that
time and wavelength division multiplexed passive optical network
(TWDM-PON) is a primary solution to NG-PON [5–7].
In TWDM-PON, resource scheduling strategy indicates the system
performances (e.g., bandwidth utilization, throughput, delay, etc.).
Since four wavelengths are used in TWDM-PON and if there is no rea-
sonable scheduling strategy for the network, on the one hand, some
wavelengths may be over-use and therefore lead to large delay; on the
other hand, other wavelengths may be bare and lead to unbalance on
bandwidth usage. Therefore, designing a robust approach to effectively
and reasonably realize the resource scheduling on wavelength and
bandwidth is significant. Some previous studies have developed a two-
dimensional (2D) resource scheduling method by using the dual flex-
ibility (i.e., wavelength and bandwidth flexibilities) of TWDM-PON
[8–11].
In resource scheduling issue, in order to support differentiated QoS,
TWDM-PON divides bandwidth into four types, namely, fixed band-
width, guaranteed bandwidth, non-guaranteed bandwidth, and the best
effort bandwidth [12]. In TWDM-PON, the monitoring and control of
the upstream traffic convergence process of all ONUs are centralized by
OLT. In other words, each ONU continuously reports the respective load
status of their transmission containers (T-CONTs) to OLT. As a central
core of transmission convergence (TC) layer, OLT subsequently moni-
tors the status of all T-CONTs and adjusts their location in time. Si-
multaneously, OLT processes two important functions, involving media
access control for upstream direction and dynamic bandwidth adjust-
ment. In the mentioned process, both of basic monitoring and basic
traffic scheduling units are T-CONTs [13–15]. T-CONT is generally di-
vided into five types, each ONU has five queues corresponding to T-
CONT-1, 2, 3, 4, 5. T-CONT-1 corresponds to a fixed bandwidth allo-
cation, and its delay requirement is strictly controlled. T-CONT-2
https://doi.org/10.1016/j.yofte.2018.12.029
Received 11 September 2018; Received in revised form 9 December 2018; Accepted 26 December 2018
⁎
Corresponding author.
E-mail address: zhangwenbo@yeah.net (W. Zhang).
Optical Fiber Technology 48 (2019) 165–172
1068-5200/ © 2019 Elsevier Inc. All rights reserved.
T