Suppose That an 11 Mpbs 802.1 Lb Lan Is Transmitting 64 Byte Frames Back to Back
11. Suppose that an 11-Mbps 802.11b LAN is transmitting 64-byte frames back-to-back over a radio channel with a bit error rate of 10-7. How many frames per second will be damaged on average? 12. The 802.11 data frame has four address fields. Why and what is the purpose of each address field? 1. What are the differences between the following types of wireless channel impairments: path loss, multipath propagation, interference from other source? 2. What is the RTS/CTS mechanism in IEEE 802.11? What problem and service does it provide and how is it implemented? What are the potential drawbacks of RTS/CTS mechanism? 3. According to the IEEE 802.11 standard, is it true or false that before a station transmits a data frame, it must first send an RTS frame and receive a corresponding CTS frame? Briefly explain your answer. 4. What is the purpose of using acknowledgements in the 802.11 MAC protocol? 5. Binary Exponential Backoff a. What is the purpose of exponential backoff algorithm used in 802.11? b. Assume two nodes have just experienced their first collision. What is the value of their respective CWs? Describe the steps that each station must now take before transmitting a data frame. c. What is the length (in time) of a backoff slot for 802.11a/b/g? How are these values determined? 6. IEEE 802.11 defines a feature called the RTS Threshold. Explain the purpose of the RTS Threshold and how it works. 7. Suppose there are two ISPs each providing WiFi access (using 802.11g) in your favorite coffee shop. Each ISP is operating its own access point (AP) and its own IP address block. a. Further suppose that each ISP has configured its AP to operate over channel 8. Will the 802.11 protocol completely fail in this scenario? Explain your answer. Discuss what happens when two stations, each associated with a different ISP, attempt to transmit at the same time. What is the aggregate transmission rate for the two ISPs in this scenario? b. Now suppose that instead of both APs using the same channel 8, one AP uses channel 2 and the other uses channel 8. How do your answers change? 8. Outline the process that occurs when an 802.11 station has a new data frame to transmit. That is describe the DCF process, without the RTS/CTS mechanism. 9. In step 4 of the CSMA/CA protocol, a station that successfully transmits a frame begins the CSMA/CA protocol for a second frame at step 2, rather than at step 1. What is the rationale of the CSMA/CA protocol designers for having such a station not transmit the second frame immediately (assuming the channel is sensed idle for DIFS)? 10. Suppose an 802.11b station is configured to always reserve the channel with the RTS/CTS sequence. Suppose this station suddenly wants to transmit 1000 bytes of data, and all other stations are idle at this time. As a function of SIFS and DIFS, compute the time required to transmit the frame and receive the acknowledgement. You can ignore propagation delay and assume no bit errors. Show transcribed image text 11. Suppose that an 11-Mbps 802.11b LAN is transmitting 64-byte frames back-to-back over a radio channel with a bit error rate of 10-7. How many frames per second will be damaged on average? 12. The 802.11 data frame has four address fields. Why and what is the purpose of each address field?
1. What are the differences between the following types of wireless channel impairments: path loss, multipath propagation, interference from other source? 2. What is the RTS/CTS mechanism in IEEE 802.11? What problem and service does it provide and how is it implemented? What are the potential drawbacks of RTS/CTS mechanism? 3. According to the IEEE 802.11 standard, is it true or false that before a station transmits a data frame, it must first send an RTS frame and receive a corresponding CTS frame? Briefly explain your answer. 4. What is the purpose of using acknowledgements in the 802.11 MAC protocol? 5. Binary Exponential Backoff a. What is the purpose of exponential backoff algorithm used in 802.11? b. Assume two nodes have just experienced their first collision. What is the value of their respective CWs? Describe the steps that each station must now take before transmitting a data frame. c. What is the length (in time) of a backoff slot for 802.11a/b/g? How are these values determined? 6. IEEE 802.11 defines a feature called the RTS Threshold. Explain the purpose of the RTS Threshold and how it works. 7. Suppose there are two ISPs each providing WiFi access (using 802.11g) in your favorite coffee shop. Each ISP is operating its own access point (AP) and its own IP address block. a. Further suppose that each ISP has configured its AP to operate over channel 8. Will the 802.11 protocol completely fail in this scenario? Explain your answer. Discuss what happens when two stations, each associated with a different ISP, attempt to transmit at the same time. What is the aggregate transmission rate for the two ISPs in this scenario? b. Now suppose that instead of both APs using the same channel 8, one AP uses channel 2 and the other uses channel 8. How do your answers change? 8. Outline the process that occurs when an 802.11 station has a new data frame to transmit. That is describe the DCF process, without the RTS/CTS mechanism. 9. In step 4 of the CSMA/CA protocol, a station that successfully transmits a frame begins the CSMA/CA protocol for a second frame at step 2, rather than at step 1. What is the rationale of the CSMA/CA protocol designers for having such a station not transmit the second frame immediately (assuming the channel is sensed idle for DIFS)? 10. Suppose an 802.11b station is configured to always reserve the channel with the RTS/CTS sequence. Suppose this station suddenly wants to transmit 1000 bytes of data, and all other stations are idle at this time. As a function of SIFS and DIFS, compute the time required to transmit the frame and receive the acknowledgement. You can ignore propagation delay and assume no bit errors.
Suppose That an 11 Mpbs 802.1 Lb Lan Is Transmitting 64 Byte Frames Back to Back
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