Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
ECE 3325 (EXAM 2) 2
| Question | Answer |
|---|---|
| Use the pulldown menus below to match the approximate transmission rate with the the wireless technology that achieves that rate. "your mileage may vary" (YMMV): 802.11 ax | 14 Gbps |
| Use the pulldown menus below to match the approximate transmission rate with the the wireless technology that achieves that rate. "your mileage may vary" (YMMV): 5G celluar | 10 Gbps |
| Use the pulldown menus below to match the approximate transmission rate with the the wireless technology that achieves that rate. "your mileage may vary" (YMMV): 802.11 ac | 3.5 Gbps |
| Use the pulldown menus below to match the approximate transmission rate with the the wireless technology that achieves that rate. "your mileage may vary" (YMMV): 4G LTE | hundreds of Mbps |
| Use the pulldown menus below to match the approximate transmission rate with the the wireless technology that achieves that rate. "your mileage may vary" (YMMV): 802.11 g | 54 Mbps |
| Use the pulldown menus below to match the approximate transmission rate with the the wireless technology that achieves that rate. "your mileage may vary" (YMMV): Bluetooth | 2 Mbps |
| 7.1-2. Infrastructure Mode. What is meant when we say that a network of devices is operating in "infrastructure mode"? | Devices communicate with each other and to the larger outside world via a base station (also known as an access point). |
| 7.2-1. Characteristics of wireless links. Which of the following statements about the characteristics of wireless links are true? | The "hidden terminal problem" happens when A sends to B over a wireless channel, and an observer, C (that can be even closer to A than B), does not detect/receive A's transmission because of physical obstacles in the path between A and C. |
| 7.2-1. Characteristics of wireless links. Which of the following statements about the characteristics of wireless links are true? | Path loss refers to the decrease in the strength of a radio signal as it propagates through space. |
| 7.2-1. Characteristics of wireless links. Which of the following statements about the characteristics of wireless links are true? | Multipath propagation occurs when portions of the electromagnetic wave reflect off objects and the ground taking paths of different lengths between the sender and a receiver, and thus arriving at the receiver at slightly different points in time. |
| 7.2-1. Characteristics of wireless links. Which of the following statements about the characteristics of wireless links are true? | The bit error rate (BER) of a wireless channel decreases as the signal-to-noise ratio (SNR) increases. |
| 7.3-1. Beacon Frames. What is the purpose of a beacon frame in WiFi (802.11) networks? | A beacon frame allows an access point to advertise its existence, and the frequency channel it is operating on, to devices that want to connect to an access point. |
| 7.3-2. Use of ACKs in WiFi. Why are link-layer ACKs used in WiFi (802.11) networks? | Because of the hidden terminal problem, a node that is transmitting and hears no collisions still doesn’t know if there was a collision at the receiver. |
| 7.3-2. Use of ACKs in WiFi. Why are link-layer ACKs used in WiFi (802.11) networks? | Wireless links are noisier than wired links, and so bit level errors are more likely to occur, making link-layer error recovery more valuable that in less-noisy wired links. |
| Suppose there are two ISPs providing WiFi access in a particular café, with each ISP operating its own AP and having its own IP address block. Further suppose that by accident, each ISP has configured its AP to operate over channel 11. | Devices will still be able to associate with one network or the other. Two devices transmitting at the same time will interfere with each other, regardless of the network to which they are associated. |
| Why does the WiFi (802.11) link-layer frame have three addresses? [Note: WiFi actually has four MAC addresses in the frame, but we’re only focusing here on the three widely used ones]. | Because both the access point that will relay this frame to the intended link-layer receiving host or router interface, as well as that intended destination host or router interface need to be specified. |
| 7.3-4. RTS/CTS frames. What is the purpose of RTS (request to send) and CTS (clear to send) frames in WiFi (802.11) networks? Select one or more of the answers below. | A CTS that is sent allows a receiver to force other nodes (other than the intended sender who sent the RTS) to refrain from transmitting, thus allowing the sender who sent the RTS to then transmit a frame with less likelihood of a collision. |
| 7.3-4. RTS/CTS frames. What is the purpose of RTS (request to send) and CTS (clear to send) frames in WiFi (802.11) networks? Select one or more of the answers below. | RTC/CTS frames helps nodes in a wireless network mitigate the effects of the hidden terminal problem. |
| 7.3-5. The 802.11 Media Access Control protocol. Which of the following statement are true about the 802.11 (WiFi) MAC protocol? | 802.11 MAC protocol performs collision avoidance. That is, an 802.11 sender and receiver can use approaches such as RTS/CTS, inter-frame spacing, and explicit acknowledgments to try avoid, rather than detect, colliding transmissions from another node. |
| 7.3-6. Bluetooth. Which of the following statement are true about the Bluetooth protocol? | Bluetooth uses TDM, FDM, polling, error detection and correction, and has sleep modes to conserve device power. Pretty sophisticated for a consumer technology! |
| 7.4-1. Elements of 4G architecture. Match the function of an element in the 4G LTE architecture with its name, using the pulldown menus: Located in a mobile device’s home network, provides authentication, access privileges in home and visited networks. | Home Subscriber Server (HSS) |
| 7.4-1. Elements of 4G architecture. Match the function of an element in the 4G LTE architecture with its name, using the pulldown menus: Router in a cellular carrier’s network, coordinates packet forwarding and routing to outside the carrier’s network. | Serving Gateway (S-GW) |
| 7.4-1. Elements of 4G architecture. Match the function of an element in the 4G LTE architecture with its name, using the pulldown menus: Element coordinates mobile device services-authentication, mobility management | Mobility Management Entity (MME) |
| 7.4-1. Elements of 4G architecture. Match the function of an element in the 4G LTE architecture with its name, using the pulldown menus: This element is on the network side of wireless link into the LTE network. | Base Station (eNode-B) |
| 7.4-1. Elements of 4G architecture. Match the function of an element in the 4G LTE architecture with its name, using the pulldown menus: This element is the wireless link between mobile device and a base station | Radio Access Network (RAN) |
| 7.4-2. IMSI. In 4G LTE cellular systems, what is an International Mobile Subscriber Identity (IMSI)? | A 64-bit identifier stored on a cellular SIM (Subscriber Identity Module) card that identifies the subscriber in the worldwide cellular carrier network system. |
| 7.4-3. Comparing three wireless network types. Consider three wireless networks that we learned about: WiFi (802.11), 4G LTE, and Bluetooth: WiFi (802.11) | Has the maximum link capacity (i.e., can deliver more bits/sec to the edge device). |
| 7.4-3. Comparing three wireless network types. Consider three wireless networks that we learned about: WiFi (802.11), 4G LTE, and Bluetooth: 4G/LTE | Can provide the farthest coverage (i.e., longest range wireless communication) from a base station. |
| 7.4-3. Comparing three wireless network types. Consider three wireless networks that we learned about: WiFi (802.11), 4G LTE, and Bluetooth: Bluetooth | Consumes the least amount of power. |
| 7.4-4. Power conserving “sleep modes”. Which of the following statements is true about “sleep modes” that allow a wireless device to “sleep” and occasionally “wake up” as a technique for saving battery life? | Both WiFi and LTE provide sleep modes. |
| 7.4-5. Connecting 4G cellular networks together. Which of the following statements is true about how 4G cellular networks (operated by different carriers/companies) connect together? | 4G networks are generally all-IP, and so cellular networks interconnect (peer) directly to each other, or peer at the cellular equivalents of the Internet Exchange Points that we saw used for interconnecting wired networks in the public Internet. |
| 7.4-6. Reliable data transfer at the link layer. Which of the following statements is true about the link-level service of reliable data transfer (using ACKs) in WiFi (802.11) networks and in 4G cellular networks? | Both WiFi and LTE provide link-level reliable data transfer. |
Created by:
DylanCanalesMane