The document discusses different multiple access protocols at the data link layer. It describes random access protocols like ALOHA, CSMA, CSMA/CD, and CSMA/CA. It also covers controlled access methods using reservation, polling, and token passing. Finally, it mentions channelization techniques for multiple access like FDMA, TDMA, and CDMA that divide the channel bandwidth between stations using frequency, time, or code respectively.

1. Multiple Access

2. Data link layer divided into two functionality-oriented sublayers
 LOGIC LINK CONTROL-Error and flow control
 MAC LAYER-Multiple access resolution

3. Taxonomy of multiple-access protocols discussed in this chapter

4. RANDOM ACCESS
In random access or contention methods
>No scheduling of time station
>No rule that which station should send next
Protocol used in this method-
ALOHA
Carrier Sense Multiple Access
Carrier Sense Multiple Access with Collision Detection
Carrier Sense Multiple Access with Collision Avoidance

5.  >1972-for Radio
 >Pure/Slotted
 >Globally used
 >Acknowledgement
 >Back off time TB
 >Vulnerable time-Time in which possibility of collision
ALOHA

6. 12.6
Frames in a pure ALOHA network

7.  >Carrier sense multiple access
 >Vulnerable time-Time need to propagate from one to another
 >Senses the medium
 >Method- 1.Persistent I
2. Non Persistent- Random amount of time
3.P-Persiustance- change of slot duration> max
propagation time
CSMA

8. 12.8
Figure 12.10 Behavior of three persistence methods

9.  >Carrier sense multiple access/collision Detection
 >Arguments algorithm to handle for collision
 >Monitors
CSMA/CD

10. 12.10
Figure 12.16 CSMA/CA

11.  >Carrier sense multiple access/collision avoidance
 >Two signal
 >For wireless –because collision cannot be detected
 >Three strategy-Interframe Space(short ifs high priority)
Contention window
Acknowledgement
CSMA/CA

12. Flow diagram for CSMA/CA

13. 12.13
CONTROLLED ACCESS
In controlled access, the stations consult one another
to find which station has the right to send. A station
cannot send unless it has been authorized by other
stations.
Reservation
Polling
Token Passing
Three popular controlled-access methods

14. Reservation access method

15. Select and poll functions in polling access method
>Primary device
>Link is available
>Select-selection of primary
>Poll-primary device verify and allow to transmit

16. Logical ring and physical topology in token-passing access method

17. CHANNELIZATION
Channelization is a multiple-access method in which
the available bandwidth of a link is shared in time,
frequency, or through code, between different stations.
Frequency-Division Multiple Access (FDMA)-Guard band
Time-Division Multiple Access (TDMA)-Access method of DLL to control PL
Code-Division Multiple Access (CDMA)-One chanel all transmission, simuntaniously
Protocol