Download Cost Efficient Algorithms for FiWi Access Network

Synopsis of Research Problem
on
Investigations on Various Energy
and
Cost Efficient Algorithms for FiWi Access Network
By
Vijendra Mishra
Supervisor
Dr. Raksha Upadhyay
Proposed Co Supervisor
Dr. Uma Rathore Bhatt
Dr. Abhay Kumar
IET DAVV, Indore
Department of Electronics and Telecommunication Engineering
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Contents
1.
Introduction .......................................................................................................................................... 3
2.
Literature Survey................................................................................................................................... 5
2.1.
ONU PLACEMENT ALGORITHMS ................................................................................................... 5
Random Approach ................................................................................................................................ 5
Deterministic Approach ........................................................................................................................ 5
Greedy Algorithm .................................................................................................................................. 5
Simulated Annealing ............................................................................................................................. 6
Tabu Search........................................................................................................................................... 6
Load Balancing ONU Placement (LBOP)................................................................................................ 6
Hybrid Algorithm ................................................................................................................................... 6
2.2.
SURVIVABILITY ALGORITHMS ....................................................................................................... 7
Sharing Backup Radios (SBR)................................................................................................................. 7
Shortest Protection Ring (SPR).............................................................................................................. 7
Ring Based Protection Considering Multiple Failure (RPMF)................................................................ 7
2.3.
ROUTING ALGORITHMS ................................................................................................................ 7
Minimum Hop Routing Algorithm (MHRA) and Shortest Path Routing Algorithm (SPRA) ................... 8
Predictive Throughput Algorithm ......................................................................................................... 8
Delay Aware Routing Algorithm............................................................................................................ 8
Capacity and Delay Aware Routing (CADAR) ........................................................................................ 8
Risk-and-Delay Aware Routing (RADAR) ............................................................................................... 8
Energy and Delay Aware Routing (EDAR) ............................................................................................. 8
2.4.
QUALITY OF SERVICE ALGORITHMS .............................................................................................. 9
Dynamic Bandwidth Allocation (DBA) Algorithm.................................................................................. 9
3.
Objectives.............................................................................................................................................. 9
4.
Methodology......................................................................................................................................... 9
6.
References .......................................................................................................................................... 10
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1. Introduction
Communication is an application of science and technology that has come to be vital for
modern existence. From the early radio and LAN to current devices such as mobile
phones and laptops, accessing the global network has become the most essential part of
our lifestyle [1]. Communication is an ever developing field, and the future holds many
possibilities in this area. One expectation for the future in this field is that, the devices
can be developed to support communication with higher data rates, longer distance and
more security. Research in this area suggests that a dominant means of supporting such
communication capabilities will be through the use of Wireless LANs, WiMAX, WiFi,
PON, FiWi etc. As the deployments of these technologies have been increases well
around the globe, it becomes important for us to understand different technologies and to
select the most appropriate one [2] [3]. The proposal provides a brief detail of FiWi
network accessing technology and its concerned issues.
FiWi is an optimum selection between both access technologies by combining the large
bandwidth capacity and high stability in optical world with the flexibility and low
deployment cost in wireless world. This makes FiWi access service an ‘‘anywhere–
anytime’’ technology [4].
Figure 1: Two segments FiWi architecture [3]
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In most of the cases, FiWi uses the ‘‘tree-mesh’’ architecture. In the above figure, a
typical FiWi architecture shows two segments, and each segment includes a Wireless
Mesh Network (WMN) at the front-end and a PON (which has a tree topology) at the
backend [3]. In each segment an ONU can drive multiple wireless gateways by wired
connection to act as the interface between the front-end and the back-end. Using wireless
devices UEs located at individual location can connect to FiWi network. Finally, packets
received from wireless gateway will go through the back-end PON and arrive at OLT,
where they will be injected into Internet. In such way, FiWi enables UEs to access
Internet with better flexibility and larger capacity [5].
In the upstream, the front-end WMN allows each UE to send its packets to any wireless
gateway. At the back-end, if WDM-PON is used, it is a P2P network where each ONU
can communicate with OLT by using a separate upstream wavelength channel and if
TDM-PON is used, it is a P2MP network where all ONUs share the same upstream
wavelength channel by means of TDM technology [5]. In the downstream, if WDM-PON
is employed as the back-end, OLT can send the packets to each ONU in a P2P way by
assigning each ONU a separate downstream wavelength channel; if TDM-PON is
employed as the back-end, OLT can broadcast the packets to all ONUs in a P2MP way
by making all ONUs share the same downstream wavelength channel. In this case, each
ONU decides to accept or reject the received packet by examining whether its destination
address is matched.
The advantages of FiWi over the other existing access technologies can be summarized
as follows [6]:
1) When compared to wireless access network, FiWi can provide larger bandwidth
capacity and better stability by means of the back-end PON, so as to reduce traffic
blocking rate and packet loss rate.
2) When compared to optical access network (i.e., PON), FiWi can provide wider
coverage and more flexible access by means of the front-end WMN which also
makes FiWi have a shorter fiber reach and thus reduce the deployment cost.\\
3) More importantly, the front-end WMN can not only self-heal from the failures and
also enhance the survivability of the back-end PON, because its mesh topology
can provide alternative routes [7].
Thus, FiWi is a promising solution for the next-generation broadband access network
which aims at larger bandwidth capacity, better stability, lower deployment cost and
more flexible access.
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Most of the work related to FiWi focus on the general topics such as ONU placement,
energy efficient algorithms, architecture of FiWi network, QoS requirement, cost analysis
routing algorithms etc. Thus proposed work focus on investigations on various energy
and cost efficient algorithms for FiWi access network.
2. Literature Survey
Many issues like ONU placement, survivability, routing and quality of service have been
explored recently, it is proposed to analyze these issues for energy and cost efficient FiWi
access network.
2.1. ONU PLACEMENT ALGORITHMS
In FiWi, ONU has a capability of transmitting and receiving both wireless and optical
signal as well as capable of wireless-optical signal conversion. ONU is responsible to
modulate wireless signals received from wireless mesh routers into upstream optical
signals that will be transmitted to the RN and also to demodulate optical signals received
from the RN into wireless signals that will be transmitted to the WMN, which means
ONUs in FiWi network possesses the function of both traditional ONUs in PONs and
gateways in WMNs. Thus, the placement of ONUs should be in such a way that it
increases the network performance and makes a cost-efficient network.
Random Approach
In this, dividing the network in multiple non-overlapping regions, after that in every
region ONUs is placed randomly. This scheme may not provide proper connectivity
because in some parts of the network ONU may be form cluster and other part may be
scant [8].
Deterministic Approach
In this, after dividing the network into multiple non-overlapping regions then we placed
the ONU at the center of each region. This approach works well in a symmetric network
and much lower processing required. But this scheme does not fit well for a non-uniform
distribution of users [9].
Greedy Algorithm
In this, either random or deterministic approach is initially used. Then according to the
minimum distance from the user, we identify the primary ONU for all the users. And try
to minimize the average distance between the ONU and its user. The Greedy Algorithm
is a heuristic, which performs local optimization of an individual ONU after the
identification of premium users for that ONU, but this solution is not globally optimal.
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The purpose of global optimization is to find the minimum average cost for all the users
with respect to multiple ONUs [10].
Simulated Annealing
This algorithm to minimize the average distance of any wireless mesh router to its
neighborhood ONU in FiWi networks. It has following phases: Initialization,
Perturbation, Cost Calculation, Acceptance and Update. In Initialization phase of SA, the
initial placement of ONU is obtained by greedy algorithm. In Perturbation phase SA
relocates the ONUs with a small random amount. In Cost Calculation phase, the
algorithm calculates the new cost of ONU placement and observed the new cost changes
with respect to old cost. In Acceptance phase, if the new cost of ONU deployment is
lower SA accept the relocation of ONUs else it remains with the old cost. In Update
phase, SA iterates the same process until no further cost improvement occurs. If no more
perturbation will reduce the cost of deployment then algorithm is said to be in
‘equilibrium state’ [11].
Tabu Search
The objective of this algorithm is to minimize the total wireless hop count from routers to
ONUs as discussed by Zeyu Zheng et.al. & with the help of this algorithm the optimal
ONU placement is done to maximize the network throughput [12,13].
Load Balancing ONU Placement (LBOP)
LBOP algorithm proposed for both type of traffic to minimize the numbers of ONUs and
load balancing among ONUs. The LBOP algorithm consists of two stages ONU
placement and load balancing. In first stage, firstly place the ONU in a network in greedy
manner one-by-one, and then find best location for everyone such that the required
number of ONU is minimized and the entire wireless router will connect to ONU under a
wireless multihop way. In second stage, the traffic load is given to each ONU according
to their subordinate wireless router. Then implement the load transferring among
different ONU until it satisfies the load balancing condition. From this algorithm the
required number of ONU is minimized [14].
Hybrid Algorithm
In [15], author proposed a hybrid algorithm for ONU placement which again handles
both types of traffic in FiWi network. Hybrid algorithm works in two stages. In first
stage, initially place the ONU at the centre region of each grid and form the set of
subordinate wireless routers under the wireless hop way and try to reduce the number of
the ONUs in such a way that all the wireless routers should communicate at least one of
the ONUs. After the first stage, less number of ONUs present in the network as compared
to initially placed ONUs. In the second stage, author is using genetic algorithm to find the
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best location of remaining ONUs in their respective grids followed by further minimizing
the number of ONUs. In this way the hybrid algorithm results in cost-efficient network.
2.2. SURVIVABILITY ALGORITHMS
Survivability is one of the key issues in FiWi access network because the network
components failure may cause huge data loss especially at back-end. The failure problem
is more severe at back-end because it carries huge amount of traffic while the wireless
front- end can self-heal from the failures. The back-end failure can be divided into two
levels the ONU-level failure and OLT-level failure. ONU-level failure occurs due to
single distribution fiber cut while OLT-level fiber is mainly caused by single feeder fiber
cut. Two different algorithms Sharing Backup Radios (SBR) and Shortest Protection
Ring (SPR) are used for the deployment of backup radios and backup fibers respectively
[16].
Sharing Backup Radios (SBR)
This algorithm is used to protect FiWi against the ONU-level failure and it gives a
suboptimal solution for the problem of deployment of backup radios by also minimizing
the cost. Different wireless-backup-paths are encouraged to traverse the same wireless
router and share the same backup radio. Therefore, the cost of backup radios is reduced
significantly. In this Dijkstra routing algorithm is used to find out the shortest path
among different ONUs in the wireless topology [17].
Shortest Protection Ring (SPR)
The proposed algorithm is used to protect FiWi against the OLT-level failure and solves
the problem of backup fiber placement. We first use the Genetic Algorithm (GA) to
cluster all segments in the network and after that backtracking method is used to find
shortest Hamiltonian ring in each cluster which helps in reducing the cost of backup fiber
[17].
Ring Based Protection Considering Multiple Failure (RPMF)
Another proposed scheme is RPMF which is used to solve the problem of segment
clustering and backup fiber deployment. To optimize the segment clustering we first
apply the Genetic Algorithm (GA) and then simulated algorithm (SA) is used to optimize
the deployment of backup fibers among the segments in each cluster [18].
2.3. ROUTING ALGORITHMS
At the front-end of FiWi the wireless router are used to inject the packets into the
wireless mesh of network. The packet travels through the mesh in multiple hops to find
one of the ONUs and finally sent to wired media with the help of central office (CO).As
the packet travels through several routers in the mesh so packet delay is the major
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problem and it increases as the mesh network becomes large. Packet loss may also occur
due to multiple failures. Thus, to handle these problems different algorithms are proposed
[19].
Minimum Hop Routing Algorithm (MHRA) and Shortest Path Routing Algorithm (SPRA)
Both work on the shortest path algorithm without considering other traffic demands.
Therefore some issues arise like increased delay, poor load balancing and high
congestion [18].
Predictive Throughput Algorithm
PTRA is link-state-based routing scheme that chooses the path which satisfies the overall
throughput requirements. This algorithm is not suitable for delay sensitive services so we
use another algorithm called DARA [18].
Delay Aware Routing Algorithm
DARA considers the end-to-end delay from the packet’s source router to a gateway or
vice versa in the front-end. The packet delay in the front-end consist of four components
i.e. propagation delay, transmission delay, slot synchronization delay and queuing delay.
DARA helps to minimize all these delays significantly [18].
Capacity and Delay Aware Routing (CADAR)
CADAR is a routing algorithm for WMN that minimizes the network delay by assigning
the radio capacities based on link states. Two wireless nodes have a link between them
and each node has one radio which advertises the states of its entire outgoing links using
Link-State Advertisement (LSA). On the basis of LSA, capacity is assigned to the links
and shortest-delay paths between the wireless nodes and gateways are calculated [19].
Risk-and-Delay Aware Routing (RADAR)
In RADAR each router at front-end advertises the wireless link state (LSA) periodically.
On the basis of LSA information link weights are assigned to the links. A path is
computed which carries the minimum average transfer delay from a router to any
gateway and vice-versa and a Risk List (RL) table is maintained in router. If failure
occurs, RL is updated and packets are rerouted [20].
Energy and Delay Aware Routing (EDAR)
This algorithm works on reducing the power consumption at both wireless and optical
part. It switches maximum no. of nodes into the sleep mode while keeping the network
performance to an acceptable limit. This algorithm first works in reducing the delay in
the network so that if wireless switch or optical nodes are in the sleep mode the
performance of network will not be affected. And the energy aware routing helps to
reduce energy consumption of network [21].
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2.4. QUALITY OF SERVICE ALGORITHMS
FiWi efficiently combines both optical and wireless networks where optical fiber given to
end user is cost efficient and improves the overall QoS of system. By combining two
different technologies leads to inept data transmission, which affects the QoS. To
improve the QoS of network Dynamic Bandwidth Allocation (DBA) algorithm is used.
Dynamic Bandwidth Allocation (DBA) Algorithm
DBA are implemented based on amount of data being generated at user end. Two
algorithms are implemented to give better QoS in FiWi networks i.e. Status Reporting
(SR) DBA and Traffic Monitoring (TM) DBA [22].

In SR DBA, ONU collects all the receive data and sends report frames to OLT. On
the basis of these frames OLT calculates and allocates bandwidth for every ONU.
 In TM DBA OLT continuously monitors the traffic sent by ONU and comparison is
done between received and previous traffic. If difference is high then step will be
high.
2.5. ENERGY SAVING ALGORITHM
The energy saving issue should be carefully considered in FiWi network. There
are mainly two types of energy saving techniques i.e. Power Saving Mode (PSM)
for WMN and ONU sleep on the PON side. In both techniques energy is saved by
turning off the transmitting devices. Due to this end-to-end latency across the
FiWi network increases and throughput of network decreases [22].
3. Objectives
i. To propose energy efficient architectures for FiWi.
ii. To develop algorithms (such as routing, survivability, awakening
and sleep) to enhance energy efficiency in FiWi.
iii. Optimum placement of ONUs and Access points to get improved
cost efficiency.
4. Methodology
Initially a random network will be selected with specified attributes like number of
nodes, number of access points, architecture etc. Then, proposed algorithm will be
implemented on the selected random network. For the proposed algorithm, various
parameters such as throughput, peer to peer delay, synchronization delay, cost etc
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will be determined. Parameter of proposed algorithm will compared with the
existing algorithm to check efficiency of network.
5. Expected Outcomes
The proposed work is expected to present following outcomes:
1) Algorithms will accord better energy and cost efficient FiWi access network.
2) Improved life time of the network for the given energy.
3) Maintained Quality of Service.
6. References
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