데통 HW1, HW2, HW3

• In CSMA, collision can still occur because propagation delay is non-zero - O 
• An algorithm is needed with CSMA to specify what a station should do if the medium is found busy. - O
• The p-persistent algorithm with binary exponential backoff is efficient over a wide range of loads - X
• The maximum utilization achievable using ALOHA can far exceed that of CSMA - X
• A compromise that attempts to reduce collisions, like nonpersistent, and reduce idle time, like 1-persistent is p-persistent - O 
• The probability of collision in CSMA is independent of the distance between the terminals - X
• If a collision occurs in CSMA, entire packet transmission time is wasted - O
• We can reduce the waste due to collision if we can stop the transmission as soon as we detect a collision - O
• With CSMA/CD the amount of wasted capacity is reduced to the time it takes to detect a collision - O 
• CSMA/CD is generally feasible in wireless - X
• In the radio coummunication on a wireless medium, the signal strength gets weaker in linearly inverse to distance - X 

 

 

medium access control

SINR - > Ethernet

1-persisten CSMA -> 2 

6/ per minute = 1/ 10초 

1/10초 * first 10 seconds = 1 

3보다 작는 확률은? 

e^-1 + 1/1!x e^-1 + 1/2!xe^-1 =5/2 x e^-1

 

 

K = 5

 

 

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Error control은 receiver 을 규제하기을 할 수 있다. receiver 의 buffer 가 overflow 되지 않으면 -> X

Transmission time 은 not proportional to the length of the frame -> X

Propagation time 은 순회하는 비트이다. 소스와 목적지 사이에서 

 

satation to emit all of the bits of a frame onto the medium = transmission

한문제 틀림