7. How does the binary exponential backoff algorithm work in the 802.11? 8. CSMA/CA provides reliable transmission and avoids collisions. Explain the benefits of additionally using the RTS/CTS technique in this case. How can we decrease the delays and overhead introduced by this technique? 9. WLAN uses fix-power scheme (the actual transmission rate will be adapted according to channel condition). Assume a WLAN BSS with one station far away from the access point and several other stations close to the access point. All terminals are backlogged, i.e., they always have data to send to the AP. Explain why this one far away station severely limits the throughput achieved by the other stations. 10. Point Coordination Function (PCF) provides contention-free frame transfer. What are the advantages and disadvantages of PCF comparing to DCF? 11. What are the three types of MAC Frame (give at least one example for each type; e.g. Beacon frame is management type)? 12. Under what function that 802.11 frames might contain four address fields