An ad Hoc network using IEEE802.11 has 4 nodes: N1, N2, N3, N4. Assume that SIFS is 1 unit of time, PIFS 2 units of time, DIFS 3 units of time, and slot time is 2 (these values are not the real values but are taken to simplify the packets scheduling). Assume that at the beginning the channel is idle (no transmission), and that at instant 1 (time instant) N2 has a packet to be sent to N4. At instant 2, both N1 and N3 have a packet to be sent to N4. Assume that the random number generator (for backoff) will give the following values for N1: 2, 5, ...; for N2: 4, 3, ...; and for N3: 1, 4, .... Assume that we don't use RTS/CTS or fragmentation, and that all data packets have the same length: 6 units of time and that the Ack packet has length 3 units of time. Furthermore the channel Bit Error Rate is assumed to be 0. Show the execution of the DCF mode of IEEE 802.11.
2. In general terms, what application areas are supported by Bluetooth?
3. What are some key characteristics that distinguish fourth-generation cellular systems from third-generation cellular systems?
4. Read the attached paper, "GPS: Location-Tracking Technology," by R. Bajaj, s. Ranaweera, and D. P. Agrawal, find out the limitations of GPS, which introduce error to GPS position calculations and prevent us from achieving the best possible accuracy.