Wireless LANs use the IEEE 802.11 standard which defines the physical and MAC layers. The physical layer uses either frequency hopping spread spectrum or direct sequence spread spectrum to transmit over radio frequencies. The MAC layer uses CSMA/CA for channel access and defines frame formats for addressing between devices in a basic service set or extended service set. Bluetooth uses a piconet topology with a master-slave relationship between devices for communication at the baseband layer, and supports both single-slave and multiple-slave communication through its L2CAP layer.

1. Chapter 15 Wireless LANs

2. 15.1 IEEE 802.11 Architecture Physical Layer MAC Layer Addressing Mechanism

3. Figure 15.1 BSSs

4. Figure 15.2 ESS

5. Figure 15.3 Physical layer specifications

6. Figure 15.4 FHSS

7. Figure 15.5 DSSS

8. Figure 15.6 MAC layers in IEEE 802.11 standard

9. Figure 15.7 CSMA/CA flowchart

10. Figure 15.8 CSMA/CA and NAV

11. Figure 15.9 Frame format

12. Table 15.1 Subfields in FC field When set to 1, means station has more data to send. More data Wired equivalent privacy. When set to 1, means encryption implemented. WEP Reserved. Rsvd Defined later. From DS When set to 1, means more fragments. More flag When set to 1, means retransmitted frame. Retry When set to 1, means station is in power management mode. Pwr mgt Defined later. To DS Defines the subtype of each type (see ). Subtype Type of information: management (00), control (01), or data (10). Type The current version is 0. Explanation Version Field

13. Figure 15.10 Control frames

14. Table 14.2 Values of subfields in control frames Acknowledgment (ACK) 1101 Clear to send (CTS) 1100 Request to send (RTS) Meaning 1011 Subtype

15. Table 15.1 Subfields in FC field Sending AP Source station Sending AP Source station Address 2 Destination station Destination station Source station BSS ID Address 3 Source station N/A N/A N/A Address 4 Receiving AP Receiving AP Destination station Destination station Address 1 1 0 1 0 From DS 1 1 0 0 To DS

16. Figure 15.11 Addressing mechanism: case 1

17. Figure 15.12 Addressing mechanism: case 2

18. Figure 15.13 Addressing mechanism: case 3

19. Figure 15.14 Addressing mechanism: case 4

20. 15.2 Bluetooth Architecture Radio Layer Baseband Layer Other Upper Layers L2CAP Layer

21. Figure 15.15 Piconet

22. Figure 15.16 Scatternet

23. Figure 15.17 Bluetooth layers

24. Figure 15.18 Single-slave communication

25. Figure 15.19 Multiple-slave communication

26. Figure 15.20 Frame format types

27. Figure 15.21 L2CAP data packet format