Sample Question Quiz 1 Flashcards
What is an SoC and why is it important?
System on a chip is a complete chip containing the necessary components such as GPU, CPU, cache, etc. Uses less power because it includes both hardware and software and has better performance.
Which of the following chips sit closer to CPU and why? Northbridge or Southbridge
The Northbridge is closer to CPU because it is directly connected to memory and GPU. The CPU can request data from RAM through northbridge memory controller.
What is GPU?
Graphics processing unit which is a specialized type of microprocessor, primary designed for quick image rendering.
What is CPU?
Central Processing Unit or the brain of the computer.
What is Application Processor (AP)
System designed to support applications running in a mobile operating system environment. Supports memory management, graphics processing, and multimedia encoding.
Most smartphones operate on which of the following CPU instruction set? ARM or x86
ARM
List at least 3 communication chips in a typical smartphone
NFC, Bluetooth, Wi-Fi, GSM, 4G, 3G
Android operating system is based on which of the following? Linux, unix, windows
Linux
Which government body regulates wireless communications in the U.S.?
FCC - Federal Communications Commission
ETSI.org
European Telecommunications Standards Institute
ITU.int
International Telecommunications Union.
Name three wireless communication applications that operate in ISM band?
Industrial, scientific, medical radio bands. Google’s Project Loon, microwave oven, WLAN, Bluetooth
What is a transceiver?
Transmitter and receiver on the same chip in smartphones
RF Basics: Transmitter
Amplifier to strengthen initial signal, oscillator to create carrier wave. Mixer to combine signal. Filter to choose the correct frequency and amplifier to strengthen output signal.
What is SNR? why is it an important system level parameter?
Signal to noise ratio. It is important because noise can ruin a signal sent so the lower the ratio, the better
What is the difference between the transmission range and detection range?
Transmission range is where devices can communicate with low error rate. Detection range is where devices can detect one another but cannot communicate
What is frequency multiplexing
When the frequency spectrum is separated into smaller bands and each user gets one of those band for the whole time. The advantage is no coordination needed but the disadvantage is the inefficient use of bandwidth
Which WiFi standard is fundamentally different from all WiFi standards?
Spread spectrum based 802.11b
In US, how many non-overlapping channels are there in 2G WiFi standard
3
What is WiFi direct
- International Standard by the WiFi Alliance
- WiFi connection without Wireless Access Point
- Protected WiFi setup
- No extra HW required
Describe hidden terminal problem?
When two nodes are transmitting to one another and a third node wants to transmit to one of the node but cannot.
What is RTS and CTS in CSMA/CA protocol?
RTS and CTS make sure that there are no collision in transmission with different nodes by deferring nodes trying to transmit to nodes that have RTS and CTS NAV.
What is RSSI and how is it measured?
Received Signal Strength Indicator
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Describe main idea behind location fingerprinting?
Location sensing based on WiFi signal
- Radio map of observed signal strength values from different locations.
- SS values observed at a user mobile device compared to radio map waves using proximity-matching algorithms to infer current user locations
What is power islanding?
A location is powered even though an electrical grid power is no longer present
What is clock gating?
Reducing dynamic power dissipation. Saves power by adding more logic to a circuit to prune the clock tree.
Bluetooth operates in which of the following frequency bands? 2.4GHz, 5GHz, 2.4MHz
2.4GHz
Why does Bluetooth use ‘frequency hopping’ method?
- Signal is broadcast over seemingly random series of radio frequencies so eavesdroppers hear only unintelligible blips
- Attempts to jam signal on one frequency succeed only at knocking out a few bits because signal hops from frequency to frequency at fixed intervals.
What is in Access Code?
Time synchronization, frequency offset compensation, paging and inquiry, and address of piconet primary
What is park mode in Bluetooth?
Admit more than 7 secondary devices into piconet by giving up active member address and getting park member address. Wakes up periodically to check for broadcast to be unmarked.
What is scatternet
Interconnection of multiple piconet through bridge nodes
How does Bluetooth achieve data rate of 24mbps?
Data is carried over WiFi link
What is near-field?
Area from antenna to point where electromagnetic field forms. Inductive coupling
What is far-field?
Area some distance from transmitting antenna where electromagnetic wave forms and fully separates from antenna
What is the power source of the passive tag?
Reader drives sinusoidal current
