Question

Wireless and Mobile Networks

1) Briefly explain why IEEE 802.11 does not use collision detection.

2)Briefly describe the IEEE 802.11 CSMA/CA procedure.

3) Consider two senders in a CDMA network. The chipping codes of sender 1 and sender
2 are (1, 1, 1, 1, 1, 1, 1, 1) and (1, 1, 1, 1, 1, 1, 1, 1) respectively. Suppose that
the two sender send 1 bit each and the combined output is (2, 0, 2, 0, 2, 2, 0, 0).
Determine the two bits of the two senders.

4) Briefly explain the mobile IP registration procedure in Mobile IP.

Answer 1

1). IEEE 802.11 is also known as wi- fi . These are the set of technical guidelines to set up the structure of wireless LANs. There is high rate of collision in IEEE802.11 and it require implementation of FULL DUPLEX RADIO capable of transmitting and receiving signal at once .

The implementation of full duplex radio increase the price thats why collision detection is not used in IEEE 802.11

2) IEEE 802.11 CSMA/CA procedure

CSMA/CA is Carrier Sense Multiple Access/Collision Avoidence . It is a MAC layer protocol for the carrier transmission in IEEE 802.11. CSMA/CA is based on the principle of "Listen Before Talk". On this line has to be checked if it is " idle" and then station start transmission.

When a wifi needs to transmit it senses the career and backoff in microseconds. If the receiver gets the frame intact it sends the acknowledgement ACK to the sender. If sender does not get ACK it retransmits the frame.

Collision avoidence technique use the packet system.

There is exchange of packets RTS ( ready to send) and CTS ( clear to send ) between the sender and the receiver end.  

simplified algorithmic approach to CSMA/CA is :

1. start

2. assemble a frame

3. is the channel idle then go to step 5 else

4. wait for random backoff time

5. Transmit RTS

6. CTS received . if yes transmit application data else go to step 4.

7. END

3) sender 1 (1,1) (1,1) (1,1) (1,1)

SENDER 2 (1,-1) (1,-1) ( 1,1) (-1,-1)

2 BIT Representation of output is : 10101100

4) MOBILE IP REGISTRATION

IP address allows the computer to send and receieve the information. There are 4 types of IP address: public , private , static , dynamic.

Mobile IP registration is the process in which mobile nodes communicate with their home agent in order to provide the current reachability.

It allows the mobile to roam freely when visiting a foreign network side by side connectinh with a home network.

The mobile ip has following components:

• Mobile Node ( MN)

• Home Agent(HA)

• Foreign Agent(FA)

• Care of Address(COA)

• Corresspondent Node(CN)

• Home network

• Foreign network

The register process allows the nodes to perform the following tasks :

• Request forwarding services during roaming in foreign network.

• Inform the home agent of the current care of address.

• Renew the about to expire registration

• De register when return back home

• Request a reverse tunnel.

Answer 2

1). IEEE 802.11 is also known as wi- fi . These are the set of technical guidelines to set up the structure of wireless LANs. There is high rate of collision in IEEE802.11 and it require implementation of FULL DUPLEX RADIO capable of transmitting and receiving signal at once .

The implementation of full duplex radio increase the price thats why collision detection is not used in IEEE 802.11

2) IEEE 802.11 CSMA/CA procedure

CSMA/CA is Carrier Sense Multiple Access/Collision Avoidence . It is a MAC layer protocol for the carrier transmission in IEEE 802.11. CSMA/CA is based on the principle of "Listen Before Talk". On this line has to be checked if it is " idle" and then station start transmission.

When a wifi needs to transmit it senses the career and backoff in microseconds. If the receiver gets the frame intact it sends the acknowledgement ACK to the sender. If sender does not get ACK it retransmits the frame.

Collision avoidence technique use the packet system.

There is exchange of packets RTS ( ready to send) and CTS ( clear to send ) between the sender and the receiver end.  

simplified algorithmic approach to CSMA/CA is :

1. start
2. assemble a frame
3. is the channel idle then go to step 5 else
4. wait for random backoff time
5. Transmit RTS
6. CTS received . if yes transmit application data else go to step 4.
7. END

3) sender 1 (1,1) (1,1) (1,1) (1,1)

SENDER 2 (1,-1) (1,-1) ( 1,1) (-1,-1)

2 BIT Representation of output is : 10101100

4) MOBILE IP REGISTRATION

IP address allows the computer to send and receieve the information. There are 4 types of IP address: public , private , static , dynamic.

Mobile IP registration is the process in which mobile nodes communicate with their home agent in order to provide the current reachability.

It allows the mobile to roam freely when visiting a foreign network side by side connectinh with a home network.

The mobile ip has following components:

• Mobile Node ( MN)
• Home Agent(HA)
• Foreign Agent(FA)
• Care of Address(COA)
• Corresspondent Node(CN)
• Home network
• Foreign network

The register process allows the nodes to perform the following tasks :

• Request forwarding services during roaming in foreign network.
• Inform the home agent of the current care of address.
• Renew the about to expire registration
• De register when return back home
• Request a reverse tunnel.