Title: Theory / Unimportant / CS / Hardware / Computer Network - Tanenbaum / 4 Medium access control sublayer

Name: Medium Access Control
Page: 212
Chapter: 3
Section: 2.2
Abbreviation: MAC
Intuition: protocols used to determine who goes next on a multiaccess channel

Question: Hypothesis for Dynamic allocation channel
Answer: Independant traffic
Page: 260
Chapter: 4
Section: 2.2
Answer2: Single channel
Answer3: Observable collision
Answer4: Continuous or Slotted time
Answer5: carrier sens or no carrier sense

Name: Independant traffic assumption
Definition: Each of the \(N\) emitters may emit or not independently of each other
Page: 260
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel

Name: Single channel assumption
Definition: All communications occur on a single channel in which a single message may be sent at a given time
Page: 260
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel

Name: Observable collision assumption
Definition: When a collision occur, it is detected by each system
Page: 260
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel

Name: Collision
Definition: The fact that many emitter send a message simultaneously
Page: 260
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel

Name: Continuous time hypothesis
Definition: Time is continuous and a message may start at any time
Page: 260
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel

Name: Slotted time hypothesis
Definition: The network allow to begin slot at very precise moments and each slot allow for a precise number of frame to be sent
Page: 260
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel

Name: Carrier sense
Definition: Being able to detect whether the channel is used or not
Page: 260
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel

Name: Contention system
Definition: Systems in which multiple users share a common channel in a way that can lead to conflicts
Page: 262
Chapter: 4
Section: 2.1
Context: Dynamic allocation channel

Name: Pure ALOHA
Definition: Each user send data as soon as they have data. A central authority repeat every data gathered. If the user don't hear his data, it means it got lost/collided. They wait a random time and resend it
Page: 262
Chapter: 4
Section: 2.1
Context: Dynamic allocation channel
DefType: Transmission protocol for many user and a channel

Name: Slotted ALOHA
Definition: Each user send data as soon as they have data and a slot start. A central authority repeat every data gathered. If the user don't hear his data, it means it got lost/collided. They wait a random time and resend it
Page: 262
Chapter: 4
Section: 2.1
Context: Dynamic allocation channel

Name: Carrier sense protocol
Definition: Protocols in which stations listen for a carrier (i.e., a transmission) and act accordingly
Page: 266
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel

Name: Carrier Sense Multiple Access
Definition: A schema of protocols
Page: 266
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel
Abbreviation: CSMA

Name: 1-persistent CSMA
Definition: When a station has data to send, it first listens to the channel to see if anyone else is transmitting at that moment. If the channel is idle, the stations sends its data. Otherwise, if the channel is busy, the station just waits until it becomes idle. Then the station transmits a frame. If a collision occurs, the station waits a random amount of time and starts all over again.
Page: 266
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel
Intuition: If two stations become ready in the middle of a third station’s transmission, both will wait politely until the transmission ends, and then both will begin transmitting exactly simultaneously, resulting in a collision.
Etymology: 1 means that it's sent with probability one when channel is idle

Name: Non-persistent CSMA
Definition: When a station has data to send, it first listens to the channel to see if anyone else is transmitting at that moment. If the channel is idle, the stations sends its data. Otherwise, if the channel is busy, the station wait a random time and restart
Page: 266
Chapter: 4
Section: 2.2
Context: Dynamic allocation channel
Intuition: If two people want to emit while channel is used, they won't wait the same amount of time

Name: \(p\)-persistent CSMA
Definition: When a station becomes ready to send, at start of a slotted channel. If it is idle, it transmits with a probability \(p\), else restart the algo at next slot
Page: 266
Chapter: 4
Section: 2.2
Variables: \(0<p<1\)
Context: Dynamic allocation channel

Name: CSMA with Collision Detection
Definition: CMSA such that transmission halts as soon as collision is detected. Then wait a random time and restart
Page: 268
Chapter: 4
Section: 2.2
Variables: \(0<p<1\)
Context: Dynamic allocation channel
Abbreviation: CSMA/CD
Assuming: Sender may discover collision while sending (and not only after)