Wireless Network Lab 2
Content
Wireless Networks
Lab Manual
Lab 2
Wireless Physical Characteristics
Objectives:
How to build and analyze wireless network models.
Understanding the difference between different physical wireless models.
Basic Definitions:
802.11a
The 802.11a standard uses the same data link layer protocol and frame format as the
original standard, but an OFDM based air interface (physical layer). It operates in the
5 GHz band with a maximum net data rate of 54 Mbit/s, plus error correction code,
which yields realistic net achievable throughput in the mid-20 Mbit/s
Using the relatively unused 5 GHz band gives 802.11a a significant advantage.
However, this high carrier frequency also brings a disadvantage: the effective overall
range of 802.11a is less than that of 802.11b/g. In theory, 802.11a signals are absorbed
more readily by walls and other solid objects in their path due to their smaller
wavelength and, as a result, cannot penetrate as far as those of 802.11b. In practice,
802.11b typically has a higher range at low speeds. However, at higher speeds,
802.11a often has the same or greater range due to less interference.
802.11b
802.11b has a maximum raw data rate of 11 M bit/s and uses the same media access
method defined in the original standard. 802.11b devices suffer interference from
other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range
include: microwave ovens, Bluetooth devices.
802.11g
Third modulation standard was ratified: 802.11g. This works in the 2.4 GHz band
(like 802.11b), but uses the same OFDM based transmission scheme as 802.11a. It
operates at a maximum physical layer bit rate of 54 M bit/s exclusive of forward error
correction codes, or about 22 M bit/s average throughput.
Like 802.11b, 802.11g devices suffer interference from other products operating in the
2.4 GHz band.
Lab 1
Wireless Networks
Lab Manual
Lab Example:
Deploy wireless network
In this lab, you are going to the effect of different physical characteristics of the
wireless nodes in BSS.
Simulation Steps:
1. Create the network (Scenario: OFDM 802.11a)
•
Menu: Topology » Deploy wireless network »:
» Technology specifications » choose technology » WLAN (infrastructure)
» Choose Geographical overlay » Cell
» Set Number of cells: 5
» Place nodes in circular fashion
» Access point node model » wlan_ethernet_slip4_adv
» Mobile node model wlan_station_adv » count per-cell = 6.
If your version of OPNET doesn’t have Deploy wireless network, you will
need to create the network yourself (from Topology >> Open Object Pallter,
add 5 access point (wlan_ethernet_slip4_adv) and 6 workstations
(wlan_station_adv) for each access point, don’t forget to name the cells (each
access point and its 6 station should have the same BSS ID) in your mind,
since it is an infrastructure network connect all Access points to a backend
server)
2. Set for all workstation node the following parameters:
» Wireless Lan » wireless lan parameters » Physical characteristics »
OFDM 802.11a
» Data rate » 11 Mbps (for all other scenarios set it to 2 Mbps)
» BSS identifier » (the ID of each cell)
3. Repeat step to for all Access points.
4. Collect the following wireless lan Global statistics:
» Data Dropped
» Delay
» Throughput
5. Duplicate the previous Scenario 4 times » rename each one as follow:
o 802.11b
o 802.11g
o Frequency hopping
o Infra red
Each time change the physical characteristics to
o Direct Sequence
Lab 1
Wireless Networks
o Extended Rate
o Frequency hopping
o Infra Red
… Respectively.
6. Run simulation
» Click the configure/run simulation button
» Notice that the simulation Duration is 10 minutes
» Click Run
7. View results
» Open Results » Compare results.
» Set the Graph view to "time average" instead of "AS IS"
» Click the hide or show all graphs button to hide the graphs.
Lab 1
Lab Manual
Lab Manual
Lab 2
Wireless Physical Characteristics
Objectives:
How to build and analyze wireless network models.
Understanding the difference between different physical wireless models.
Basic Definitions:
802.11a
The 802.11a standard uses the same data link layer protocol and frame format as the
original standard, but an OFDM based air interface (physical layer). It operates in the
5 GHz band with a maximum net data rate of 54 Mbit/s, plus error correction code,
which yields realistic net achievable throughput in the mid-20 Mbit/s
Using the relatively unused 5 GHz band gives 802.11a a significant advantage.
However, this high carrier frequency also brings a disadvantage: the effective overall
range of 802.11a is less than that of 802.11b/g. In theory, 802.11a signals are absorbed
more readily by walls and other solid objects in their path due to their smaller
wavelength and, as a result, cannot penetrate as far as those of 802.11b. In practice,
802.11b typically has a higher range at low speeds. However, at higher speeds,
802.11a often has the same or greater range due to less interference.
802.11b
802.11b has a maximum raw data rate of 11 M bit/s and uses the same media access
method defined in the original standard. 802.11b devices suffer interference from
other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range
include: microwave ovens, Bluetooth devices.
802.11g
Third modulation standard was ratified: 802.11g. This works in the 2.4 GHz band
(like 802.11b), but uses the same OFDM based transmission scheme as 802.11a. It
operates at a maximum physical layer bit rate of 54 M bit/s exclusive of forward error
correction codes, or about 22 M bit/s average throughput.
Like 802.11b, 802.11g devices suffer interference from other products operating in the
2.4 GHz band.
Lab 1
Wireless Networks
Lab Manual
Lab Example:
Deploy wireless network
In this lab, you are going to the effect of different physical characteristics of the
wireless nodes in BSS.
Simulation Steps:
1. Create the network (Scenario: OFDM 802.11a)
•
Menu: Topology » Deploy wireless network »:
» Technology specifications » choose technology » WLAN (infrastructure)
» Choose Geographical overlay » Cell
» Set Number of cells: 5
» Place nodes in circular fashion
» Access point node model » wlan_ethernet_slip4_adv
» Mobile node model wlan_station_adv » count per-cell = 6.
If your version of OPNET doesn’t have Deploy wireless network, you will
need to create the network yourself (from Topology >> Open Object Pallter,
add 5 access point (wlan_ethernet_slip4_adv) and 6 workstations
(wlan_station_adv) for each access point, don’t forget to name the cells (each
access point and its 6 station should have the same BSS ID) in your mind,
since it is an infrastructure network connect all Access points to a backend
server)
2. Set for all workstation node the following parameters:
» Wireless Lan » wireless lan parameters » Physical characteristics »
OFDM 802.11a
» Data rate » 11 Mbps (for all other scenarios set it to 2 Mbps)
» BSS identifier » (the ID of each cell)
3. Repeat step to for all Access points.
4. Collect the following wireless lan Global statistics:
» Data Dropped
» Delay
» Throughput
5. Duplicate the previous Scenario 4 times » rename each one as follow:
o 802.11b
o 802.11g
o Frequency hopping
o Infra red
Each time change the physical characteristics to
o Direct Sequence
Lab 1
Wireless Networks
o Extended Rate
o Frequency hopping
o Infra Red
… Respectively.
6. Run simulation
» Click the configure/run simulation button
» Notice that the simulation Duration is 10 minutes
» Click Run
7. View results
» Open Results » Compare results.
» Set the Graph view to "time average" instead of "AS IS"
» Click the hide or show all graphs button to hide the graphs.
Lab 1
Lab Manual
