1.You would like to setup an IEEE 802.11n Wireless LAN works in 5.7 GHz U-NII band. Assume the antenna gain of the wireless access point is 3.2 dBi, the transmitter power is 100 mW, antenna gain for the wireless receiver is 2 dBi, and the minimal required received signal power (receiver sensitivity) is -68 dBm for the data rate of 114 Mbps. Assuming other attenuation is negligible and only free space path loss is considered. If the distance that this wireless LAN needs to cover equals to xx meters (where xx is the last two digits of your UNI id), please calculate the fade margin.
For link budget purpose, if we consider the system is acceptable when the fade margin is greater than 10 dB, is the above setup acceptable? If not, what can we do to make it acceptable?
Please show the calculation and process in detail
2.Answer the following questions about the MAC mechanism of WLAN.
1)What are CSMA/CD and CSMA/CA, respectively? Why CSMA/CD, which is commonly used in Ethernet, is not adopted for wireless LAN standard?
2)What is the hidden node problem in wireless environment? Illustrate the problem using a figure. Can CSMA/CA solve the hidden node problem? If not, how this problem is addressed in IEEE 802.11 standard? How can you enable this mechanism?