gsc/pub/master/phuynh/doc/ch4_planning... · Web viewThe hybrid WMNs can utilize multiple technologies for both WMN backbone and backhaul. Since the growth of the WMNs depend heavily

Chapter 4Planning, Designing, and Implementing the Simulation

4.1 Introduction to Smart Grid Wireless

Infrastructure Planing (SG-WIP) Tool

The SG-WIP is a Wireless Network Topology Planning Application. We has developed

this planning tool to assist the planning, and desginning phase of the AMI wireless

network infrastructure. Figure 4.1 shows the GUI of SG-WIP.

The SG-WIP is a Google Maps mashup [29, 30]. It can provide the information about the

geographical location of the network topologies, network devices, or the residental

housing units in the service areas of the utility.

Figure 4. 1 SG-WIP tool for planning AMI wireless infrastructure network in Colorado Springs

In the network planning phase, we has conducted some researches that use the SGWIP

tool.

The research for antenna placement of the WiMAX/WiFi networks has employed the

SG-WIP platform as a tool to extract information of the geographical network

topologies such as housing unit locations, or street light poles.

Figure 4.2 shows the planning antennae placement for the smart meters and the

WiMAX/Wi-Wi-Fi gateway on the Google Maps.

Figure 4. 2 Using SG-WIP tool for planning the antennae position. The WiMAX/Wi-Fi gateway was place on streetlight pole.

The research about housing unit density of the designing wireless networks has also

used the SGWIP platform to gather the distribution of the housing units.

Figure 4.3 shows the WLAN topology size 100x100 square meters that has fifty

housing units.

Figure 4. 3 This WLAN topology (100x100 square meters) has a high density of resident housing units.

The exported information about the network topologies from SG-WIP platform, as well

as the research results about the housing unit density, and the antenna locations can help

the AMI network infrastructure researchers and designers in the simulation and analysis

of the wireless network infrastructure of the AMI.

4.2 Planning the Network Simulation

The following network topologies will be simulated:

o Wireless Local Area Network (WLAN)

o Wireless Neighborhood Area Network (WNAN)

o Wireless Metropolitan Area Network (WMAN)

o Wide Area Network (WAN)

The main purpose is for evaluating the network throughput of the Hybrid

WiMax/WiFi Infrastructure that will be employed for the AMI meter reading

reporting application

o Network topologies

WiMax, WiFi technologies

Grid Topology: with pre-defined distance between wireless nodes

Adequate bandwidth data link connection

o Applications

Traffic pattern: Up-link data flows from the Smart Meter nodes to the

Utilities Data Center node

Each Smart Meter sends one meter reading message to the Data Center in

every second. The network throughput is calculated based on the number

of arrived messages in every one second at the Data center.

o The network throughput is measured from many simulation experiments that

have the inputs as following:

Number of Smart Meter nodes

Number of Wireless Mesh Hops, and Access Points

Number of Wimax/WiFi Gateways

Number of WiMAX Base Stations

The transmission delay (Tx Delay) of a meter data message is designed to measure

the average delay of the transmission of a meter data message throughout the network

infrastructure.

4.3 Designing the Network Simulation

4.3.1 Physical Network Model

4.3.1.1 Hybrid WMN Architecture

There are three types of WMNs: Flat WMN, Hierarchical WMN, and Hybrid WMN [21].

The brief description for these WMN categories are as following:

4.3.1.1.1 Flat Wireless Mesh Network

The flat WMN includes nodes that have roles as both client and router. The nodes can

perform the networking functionalities such as routing, network configuration, services,

and other applications. This architecture is similar to the Ad-hoc wireless network and it

is the simplest type among the three WMN architecture types. Its disadvantages are lack

of network scalability and high resource constraints.

4.3.1.1.2 Hierarchical Wireless Mesh Network

The hierarchical WMN has multiple tiers or levels. The client nodes form the lowest tier

in the hierarchy. The client nodes communicate together through the backbone network

formed by WMN routers. The WMN routers are the dedicated nodes for routing

functions. They are not source or destination of data traffic like the client nodes. In the

backbone network, there are some router nodes that may have an external connections to

the other resources such as the Internet, and other servers in a wired networks, then such

nodes are called gateway nodes.

4.3.1.1.3 Hybrid Wireless Mesh Network

Hybrid WMN is a special case of the hierarchical WMN where the WMN utilizes other

wireless networks for communication. For example, the hierarchical WMN that has the

client and router nodes used the Wi-Fi technology, can employ the infrastructure-based

networks such as cellular, WiMAX, or satetlite networks to connect to the Internet.

The hybrid WMNs can utilize multiple technologies for both WMN backbone and

backhaul. Since the growth of the WMNs depend heavily on the ability to work with

other existing wireless networking solutions, this architecture type is very important in

the future.

In the figure 4.4, the WiMAX has been use directly as part of Wi-Fi mesh network. The

WiMAX Subscriber Terminal put on the Wi-Fi Mesh Access Point. So the Wi-Fi

Networks automatically are more reliable in wider coverage area, and reduce cost of

connections that are caused by cable drawing in the gateway installation.

Figure 4. 4 WiMAX as backhaul inter Wi-Fi mesh networks (source: Intel)

4.3.1.2 WiMAX/WiFi Network Infrastructure

Basically, the WM Communication Network component provides the data transportation

services. The requests and responses from Meter Data Center component and Wi-Fi

Smart Meter component will be delivered by the using to the transportation services of

WM Communication Network component.

The WM Communication Network component has three layers of network services like

the first three layers of the OSI model [22]:

Figure 4. 5 Logical view of the WM Communication Network includes the first three layers of the OSI model

The WM Communication Network is an integrated Wireless Mesh Network (WMN),

which uses Wi-Fi and WiMAX technologies [17]. The WM Communication Network has

the WiMAX Base Station, the WiMAX/Wi-Fi Gateway, and Wi-Fi Dual Band Mesh

Routers.

The figure 4.6 shows the physical model of the wireless mesh communication network.

The WiMAX Base Stations are connected to the Meter Data Center through wired

network. The Wi-Fi mesh routers are at the bottom level of the network hierarchy and can

connect with the Wi-Fi smart meters. Wi-Fi smart meters connect to the meter data center

via the hybrid WiMAX/Wi-Fi Communication Network.

Figure 4. 6 Physical model of the WM Communication Network. The network hierarchy includes the Wi-Fi Mesh Routers, the WiMAX/Wi-Fi Gateways, and the WiMAX BS.

4.3.1.3 Overview of NS-3 WiMAX Module

The NS-3 WiMAX model attempts to provide an accurate MAC and PHY level

implementation of the IEEE 802.16 specification with the Point-to-multipoint (PMP)

mode and the Wireless MAN-OFDM PHY layer. The WiMAX model composed of three

layers:

The MAC Convergence Sublayer (MAC-CS)

The MAC Common Part Sublayer (MAC-CPS)

The Physical (PHY) layer

The MAC Convergence Sublayer (CS)

The MAC-CS in this module implements the Packet CS, designed to work with the

packet-based protocols at higher layers. The CS is responsible of receiving packet from

the higher layer and from peer stations, classifying packets to appropriate connections (or

service flows) and processing packets. It keeps a mapping of transport connections to

service flows. This enables the MAC CPS identifying the Quality of Service (QoS)

parameters associated to a transport connection and ensuring the QoS requirements.

The MAC Common Part Sublayer (MAC-CPS)

The MAC Common Part Sublayer (CPS) is the main sublayer of the IEEE 802.16 MAC

and performs the fundamental functions of the MAC. The module implements the Point-

Multi-Point (PMP) mode. In PMP mode BS is responsible of managing communication

among multiple SSs. The key functionalities of the MAC-CPS include framing and

addressing, generation of MAC management messages, SS initialization and registration,

service flow management, bandwidth management and scheduling services.

Framing and Management Messages

The module implements a frame as a fixed duration of time, i.e., frame boundaries are

defined with respect to time. Each frame is further subdivided into downlink (DL) and

uplink (UL) subframes. The module implements the Time Division Duplex (TDD) mode

where DL and UL operate on same frequency but are separated in time. A number of DL

and UL bursts are then allocated in DL and UL subframes, respectively. Since the

standard allows sending and receiving bursts of packets in a given DL or UL burst, the

unit of transmission at the MAC layer is a packet burst. The module implements a special

PacketBurst data structure for this purpose. A packet burst is essentially a list of packets.

In the case of DL, the subframe is simulated by transmitting consecutive bursts (instances

PacketBurst). In case of UL, the subframe is divided, with respect to time, into a number

of slots. The bursts transmitted by the SSs in these slots are then aligned to slot

boundaries. The frame is divided into integer number of symbols and Physical Slots (PS)

which helps in managing bandwidth more effectively. The number of symbols per frame

depends on the underlying implementation of the PHY layer. The size of a DL or UL

burst is specified in units of symbols.

Network Entry and Initialization

The network entry and initialization phase is basically divided into two sub-phases, (1)

Scanning and synchronization and (2) Initial ranging. The entire phase is performed by

the LinkManager component of SS and BS.

Connections and Addressing

All communication at the MAC layer is carried in terms of connections. The standard

defines a connection as a unidirectional mapping between the SS and BS's MAC entities

for the transmission of traffic. The standard defines two types of connections: the

Management Connections for transmitting control messages and the Transport

Connections for data transmission. Note that each connection maintains its own

transmission queue where packets to transmit on that connection are queued. The

ConnectionManager component of BS is responsible of creating and managing

connections for all SSs.

Scheduling Services

The module supports the four scheduling services defined by the IEEE 802.16-2004

standard:

Unsolicited Grant Service (UGS)

Real-Time Polling Services (rtPS)

Non Real-Time Polling Services (nrtPS)

Best Effort (BE)

These scheduling services behave differently with respect to how they request bandwidth

as well as how the it is granted. Each service flow is associated to exactly one scheduling

service, and the QoS parameter set associated to a service flow actually defines the

scheduling service it belongs to. When a service flow is created the UplinkScheduler

calculates necessary parameters such as grant size and grant interval based on QoS

parameters associated to it.

WiMAX PHY Model

The Wireless MAN OFDM PHY specifications is implemented. This specification is

designed for non-light-of-sight (NLOS) including fixed and mobile broadband wireless

access. The proposed model uses a 256 FFT processor, with 192 data subcarriers. It

supports all the seven modulation and coding schemes specified by Wireless MAN-

OFDM. It is composed of two parts: the channel model and the physical model.

Channel model

When a physical device sends a packet (FEC Block) to the channel, the channel handles

the packet, and then for each physical device connected to it, it calculates the propagation

delay, the path loss according to a given propagation model and eventually forwards the

packet to the receiver device.

Physical model

The physical layer performs two main operations: (i) It receives a burst from a channel

and forwards it to the MAC layer, (ii) it receives a burst from the MAC layer and

transmits it on the channel.

Transmission Process: A burst is a set of WiMAX MAC PDUs. At the sending process, a

burst is converted into bit-streams and then splitted into smaller FEC blocks which are

then sent to the channel with a power equal P_tx.

Reception Process: The reception process includes the following operations:

1- Receive a FEC block from the channel. 2- Calculate the noise level. 3- Estimate the

signal to noise ratio (SNR) with the following formula. 4- Determine if a FEC block can

be correctly decoded. 5- Concatenate received FEC blocks to reconstruct the original

burst. 6- Forward the burst to the upper layer.

The below figure 4.3 shows an overview of the WiMAX sublayers traversed for

transmitting and receiving a packet. More detailed information about the NS-3 WiMAX

model is preseneted in [ref-paper].

Figure 4. 7 NS-3 WiMAX protocol stack overview

4.3.1.4 Overview of NS-3 Wi-Fi Module

The NS-3 802.11 model provides an accurate MAC-level implementation of the 802.11

specification and the PHY-level model of the 802.11a and 802.11b specifications.

There are four levels that were implemented in the current implementation:

The PHY layer model

The so-called MAC low models

The so-called MAC high models

A set of Rate control algorithms used by the MAC low models

The PHY layer implements a single 802.11a model in the ns3::WifiPhy class, and

recently extended to cover 802.11b physical layers.

The MAC low layer is split in 3 components:

ns3::MacLow takes care of RTS/CTS/DATA/ACK transactions

ns3::DcfManager and ns3::DcfState implement the DCF functions

ns3::DcaTxop and ns3::EdcaTxopN handle the packet queue, packet

fragmentation, and packet retransmissions.

The MAC high models contain the implementations for three Wi-Fi topological elements

– Access Point (AP) implemented in ns3::ApWifiMac, non-AP Station (STA)

implemented in ns3::StaWifiMac, and STA in an Independent Basic Service Set (IBSS)

implemented in ns3::AdhocWifiMac.

Rate control Algorithms include:

ns3::ArfWifiManager

ns3::AarfWifiManager

ns3::IdealWifiManager

ns3::CrWifiManager

ns3::OnoeWifiManager

ns3::AmrrWifiManager

ns3::CaraWifiManager

ns3::AarfcdWifiManager

The below figure 4.4 shows the overview of the Wi-Fi L2 sublayers traversed for

transmitting and receiving a packet. More detailed information about the NS-3 Wi-Fi

model is preseneted in [ref-paper].

Figure 4. 8 NS-3 Wi-Fi layer 2 stack overview

4.3.2 Application Model

4.3.2.1 Client-Server architecture

The AMI metering data collection process includes three components that are Meter Data

Center, Wireless Mesh (WM) Communication Network, and Wi-Fi (WF) Smart Meter.

The Meter Data Center component accesses the WF Smart Meter’s reading via the WM

Communication Network as in the Figure 4.9.

Figure 4. 9 Smart meters access the Meter data center through the Wireless mesh communication network

4.3.2.2 Meter data traffic generation

Our current software simulates constant bit rate traffic. We allow users specifying the

starting time of packet streams. This allows for better network performance since the

packets from different nodes will not collide. It also helps debug the end to end

transmission and ensures that the network properly delivers the packets.

4.3.2.3 NS-3 Server application

An UDP protocol Server. It receives the meter messages.

4.3.2.4 NS-3 Client application

An UDP protocol Client. It sends the meter messages to the Server.

4.3.3 WLAN Simulation Design

4.3.3.1 Topology Configuration

Standard: WiFi IEEE 802.11b

Connection mode: Infrastructure

Smart Meter (SM) at random position within the coverage area of the

corresponding AP

The WiFi AP has the coverage range of 100 meters

Number of SMs: [1 – 100]

WiFi link capacity: 11Mbps

4.3.3.2 Application Configuration

Server application is installed on the AP.

Client application is installed on SM.

Each Client application will send one meter message with 20 bytes length

to the Server application by using the Internet protocol UDP.

The Client application’s Data-Rate property is set to 20 bytes x 8 bits =

160bps = 0.160kbps

4.3.3.3 Simulation Planning

Repeatedly running the simulation scenarios with the different number of

SMs

Output: the network throughput, Tx Delay

4.3.3.4 Results Analysis and Conclusion

Calculate the average network throughput, Tx delay

Conclusion: Do the AP receive all of the messages from the SMs in 1

second?

4.3.4 WNAN Simulation Design


Standard: WiFi IEEE 802.11a

Connection mode: Mesh

The Mesh Routers (MR) /Access Points (AP) are installed in the Grid

topology

o Distance between adjacent nodes (horizontal and vertical): 200

meters

Number of MRs/APs: [1 – 9]

WiFi link capacity: 54Mbps


Server application is installed on the Gateway (GW).

Client application is installed on APs.

Each Client application will send 100 messages, which have 20 bytes

length, to the Server application by using the Internet protocol UDP.

The Client application’s Data-Rate property is set to 100 x 20 bytes x 8

bits = 16000bps = 16kbps



MRs and APs

Output: the network throughput, Tx delay



Conclusion: Do the GW receive all of the messages from the APs in 1

second?

4.3.5 WMAN Simulation Design


Standard: WiMAX IEEE 802.16d

Connection mode: Point-To-MultiPoint

The Subscribers (SS)/Gateways (GW) are installed in the grid topology.

Distance between adjacent nodes (horizontal and vertical): 1,000 meters

Number of SSs/GWs: [1 -10]

WiMAX link capacity: 4Mbps


Server application is installed on the Base Station (BS).

Client application is installed on SSs.

Client application will send 900 messages, which have 20 bytes length, to

the Server application by using the Internet protocol UDP.

The Client application’s Data-Rate property is set to 900 x 20 bytes x 8

bits = 144,000bps = 144kbps



SSs/GWs




Conclusion: Do the BS receive all of the messages from the SSs/GWs in 1

second?

4.3.6 WAN Simulation


Standard: Ethernet EEE 802.3

Connection mode: Point-To-Point

The BSs are connected to the Hub (or Data Center) in the Star topology

Number of BS: [1-20]

Ethernet link capacity: 10Mbps


Server application is installed on the Hub (or DC)

Client application is installed on BSs.

Client application will send 9,000 messages, which have 20 bytes length,

to the Server application by using the Internet protocol UDP.

The Client application’s Data-Rate property is set to 9,000 x 20 bytes x 8

bits = 1,440,000bps = 1.44Mbps



BSs




Conclusion: Do the DC receive all of the messages from the BSs in 1

second?

4.4 Implementing the Network Simulation

4.4.1 WLAN Simulation

4.4.1.1 NS-3 Script

Name: sm-ap-sim.cc

Description: This script implements the network model that simulates the

AMI meter data reporting process in a WLAN topology. The simulation

scenarios have one WiFi Access Point (AP) and a number of the smart

meters (SM). The network devices are layout in a grid topology. The AMI

meter data reporting application will send the meter messages from the

SMs to the AP.

The source code of this script is in the Appendix session.

Syntax:

o Input:

nbSM - number of smart meter nodes to create [1]

duration - duration of the simulation in seconds [10]

verbose - turn on all WimaxNetDevice log components [false]

data-rate - packet data rate [0.160kbps]

statistic-start - the statistic is started at (second) [0]

o Output:

In every second:

Transmit (Tx) Packets, Receive (Rx) Packets, and

Maximum Tx Delay

In simulation period:

Average Transmit (Tx), Receive (Rx), and Transmit Delay

(TxDelay)

4.4.1.2 Linux Shell Script

Name: sm-ap-sim.sh

Description: Batch running the WLAN simulation application. This shell

script generates many WLAN simulation scenarios. Then it simulates the

scenarios, and logs the simulation results in the text files.

Syntax:

Input: none

Output: List of the log file names that store the simulation results

4.4.2 WNAN Simulation

4.4.2.1 NS-3 Script

Name: ap-gw-sim.cc


AMI meter data reporting process in a WNAN topology. The simulation

scenarios have one WiMAX/WiFi gateway and a number of the mesh

routers. The network devices are layout in a grid topology. Some of the

mesh routers are configured as the APs. The AMI meter data reporting

application will send the meter messages from the APs to the gateway.


Syntax:

o Input:

x-size - number of columns of the grid [3]

y-size - Number of rows of the grid [3]

step - distance between two adjacent nodes (meter) [190]

access-points - number of WiFi APs [1]

data-rate - packet data rate [20kbps]

statistic-start - the statistic is started at (second) [0]

o Output:

In every second:


Maximum Tx Delay



(TxDelay)


Name: ap-gw-sim.sh

Description: Batch running the WNAN simulation application. This shell

script generates many WNAN simulation scenarios. Then it simulates the


Syntax:

o Input: none

o Output:

List of the log file names that store the simulation results

4.4.3 WMAN Simulation

4.4.3.1 NS-3 Script

Name: gw-bs-sim.cc


AMI meter data reporting process in a WMAN topology. The simulation

scenarios have one WiMAX Base Station and a number of the Subscriber

Stations (or WiMAX/WiFi Gateways). The network devices are layout in

a grid topology. The AMI meter data reporting application will send the

meter messages from the Subscriber Stations to the Base Station.


Syntax:

o Input:

nbSS - number of subscriber station to create [1]

scheduler - type of scheduler to use with the network devices [0]

duration - duration of the simulation (second) [10]


data-rate - packet data rate [144kbps]

statistic-start - statistic started at (second) [0]

o Output:

In every second:


Maximum Tx Delay



(TxDelay)


Name: gw-bs-sim.sh

Description: Batch running the WMAN simulation application. This shell

script generates many WMAN simulation scenarios. Then it simulates the


Syntax:

o Input: none

o Output: List of the log file names that store the simulation results

4.4.4 WAN Simulation

4.4.4.1 NS-3 Script

Name: bs-dc-sim.cc


AMI meter data reporting process in a MAN topology. The simulation

scenarios have one Hub and a number of the WiMAX Base Stations. The

network devices are layout in a star topology. The AMI meter data

reporting application will send the meter messages from the Base Stations

to the Hub node (or the Data Center).


Syntax:

o Input:

nbBS - number of base station to create [1]

duration - duration of the simulation (second) [10]


data-rate - packet data rate [1.44Mbps]

statistic-start - statistic started at (second) [0]

o Output:

In every second:


Maximum Tx Delay



(TxDelay)


Name: bs-dc-sim.sh

Description: Batch running the WAN simulation application. This shell

script generates many WAN simulation scenarios. Then it simulates the


Syntax:

o Input: none

o Output: List of the log file names that store the simulation results

Documents

gsc/pub/master/phuynh/doc/ch4_planning... · Web viewThe hybrid WMNs can utilize multiple technologies for both WMN backbone and backhaul. Since the growth of the WMNs depend heavily