P1: Consider the single-sender CDMA example in Figure 6.5. What would be the senderâ??s output (for the 2 data bits shown) if the senderâ??s CDMA code were (1, -1, 1, -1, 1, -1, 1, -1)?
P2: Suppose an 802.11b station is configured to always reserve the channel with the RTS/CTS sequence. Suppose this station suddenly wants to transmit 1,000 bytes of data, and all other stations are idle at this time. As a function of SIFS and DIFS, and ignoring propagation delay and assuming no bit errors, calculate the time required to transmit the frame and receive the acknowledgement.
P3: Consider the following idealized WiMax scenario. The downstream sub-frame (see Figure 6.17) is slotted in time, with N downstream slots per sub-frame, with all time slots of equal length in time. There are four nodes, A, B, C, and D, reachable from the base station at rates of 10 Mbps, 2.5 Mbps, and 1 Mbps, respectively, on the downstream channel. The base station has an infinite amount of data to send to each of the nodes, and can send any one of these nodes during any time slot in the downstream sub-frame.
a. What is the maximum rate at which the base station can send the nodes, assuming it can send to any node it chooses during each time slot? Is your solution fair? Explain and define what you mean by â??fair.â?
b. If there is a fairness requirement that each node must receive an equal amount of data during each downstream sub-frame, what is the average transmission rate by the base station (to all nodes) during the sub-frame? Explain how you arrived at your answer.
c. Suppose that the fairness criterion is that any node can receive at most twice as much data as any other node during the sub-frame. What is the average transmission rate by the base station (to all nodes) during the sub-frame? Explain how you arrived at your answer.
P4: In mobile IP, what effect will mobility have on end-to-end delays of data-grams between the source and destination?