What are hidden station problem and exposed station problem in WLAN? How are the problems solved?
Hidden station problem: B is sending data to A, and after some time C also wants to send data to B. but C is not in the range of B and so it will be unaware of the transmission between B and A, and so C will send data to A and therefore there will be a collision.
Exposed station problem: station A is sending data to B and C also wants to send data to D, but since C is in the transmission range of A, C will not send data to D. But the transmission between C and D will not affect the transmission between A and B.
The hidden node can solve be solved by the use of handshaking. B before sending data to A, will first send request to send (RTS) to A. after that if A is ready to receive data from B then it will respond by sending Clear to send(CTS) to B, which will also be received by C since it will also in the transmission range of A. as a result of which C will stop transmission for the time period that is been specified in the CTS.
The use of handshaking is unable to prevent handshaking. C stops transmission for the time period specified in the RTS as it is in the range of A, but does not receive the CTS send by B. as a result of which it send RTS to D, and if D sent CTS to C then it collides with the data sent by A to B(also received by C).
USE OF HANDSHAKING TO PREVENT HIDDEN NODE PROBLEM
USE OF HANDSHAKING TO PREVENT EXPOSED NODE PROBLEM
What is meant by access control? What are the contention-based and contention free access control mechanisms?
Briefly describe the congestion control, slow start and fast retransmit mechanism.
What is hand-off? What are the different hand-off strategies? Discuss the merits and demerits of each such strategy?
Write a C program to find the factorial of any number.
What is ISO 9000 Certification? How to Get ISO 9000 Certification?
