Sample Question Quiz 2 Flashcards
What is the near-far power problem in cellular communication? How is it solved?
Users close to the tower overpower the uplink signal minimizing capacity on the thread channel.
- Solution: Continuous control of transmit power based on signal strength
Assume that a 1x1 cellular system achieves a data rate of 1mbps. What will be the expected data rate of 4x4 MIMO system?
1mbps x 4
Which cellular standard uses ‘continuous spectrum’?
LTE Advanced
How is the packet loss prevented during handover in an LTE system?
Packet forwarding process that buffers and transfers undelivered data.
How is ‘Inter-Cell Interference Coordination’ achieved in LTE advanced?
Fractional Frequency Reuse (FFR). It separates the frequency bands and allocates the band efficiently to prevent signal interference from adjacent node.
Describe the main idea behind coordinated multiple point method in LTE advanced?
CoMP coordinates multiple eNodeBs to communicated with UE. It reduces inter-cell interference by increasing throughput
What is carrier aggregation in LTE advanced?
Carrier aggregation combines individual component carriers to increase data rate and capacity of the networks.
- Intra-band contiguous, Intra-band non-contiguous, inter-band
What does ‘instruction register’ hold?
Hold queued instructions
What does ‘instruction pointer’ hold?
Hold the address of the next instruction to be executed.
What is RISC?
Reduced Instruction Set Computer
What is CISC?
Complex Instruction Set Computer
How are RISC and CISC different?
In CISC, an instruction will take several steps to complete and at each step, multiple execution of instructions can overlap. Instructions will take more than one cycle to complete. Meanwhile, RISC execute one instruction at a time in one machine cycle.
What are the flags of program status registers?
- Condition code flags
- Interrupt Disable bits
- Sticky overflow flag - Q-flag
- T-Bit
- Mode bits
- J bits
What is the purpose of hidden registers in ARM?
Banked registers are available only when the processor is in a particular mode except the user mode. When the processor is in a certain mode and has access to certain registers, the user mode registers will not be affected.
What is the role of SPSR?
Saved program status register
- All processor modes except system and user mode have it
- Records the pre-exception value of CPSR and copied to SPSR of the processor mode
- Exception handler can restore CPSR to the value prior to taking exception
What is the salient feature of barrel shifter?
Enables shifting 32 bit operand in one of the source registers left or right by a specific number of positions within the cycle time of instruction
Which parts of CPSR are affected when compare instructions are used?
Only the CPSR flags
What is thumb mode?
Allows code to be smaller because of the 16bit compressed form. The code density is better than most CISC and features dynamic decompression in pipeline
What is Jazelle mode in ARM?
The mode accelerates the execution of Java bytecode
What is a co-processor in the context of ARM?
Register transfer and memory transfer instructions are distinct from the main ARM processor.
What is the difference between an Array processor and a vector processor?
An array processor has instruction operating on multiple data elements at the same time. A vector processor has instructions operating on multiple data elements in consecutive time steps.
What is big.Little system?
Different types of job require different processing power. Little for sms, voice call, music. Big for video streaming, big calculations, and gaming.
How should the frequency be scaled if we want to reduce energy consumption by 9 times?
?
What is TrustZone and how does it work?
TrustZone deals with security features in many digital electronic devices such as set-top boxes, smart phones, payment and network equipment.
Its software application built directly into hard drive.
How does the satellite construct the navigation information it sends to the receiver?
With ground control system. GCS track GPS satellites, estimate clock and orbit, keep GPS time, and upload data that describes clock and orbit for each sv.
Why is L-band hosen for GPS related communication?
It has a frequency range high enough to penetrate through buildings and terrain to ensure best signal.
Describe the basic idea behind Capacitive Accelerometer?
When there are two microstructures next to each other, they have a capacitance between them. If an accelerative force moves one of the structures, then the capacitance will change. Adding some circuitry to convert from capacitance to voltage makes an accelerometer.
Describe the basic idea behind Capacitive Gyroscope.
Coriolis force is proportional to both angular velocity of the rotating object and velocity of the object moving towards or away from axis rotation. It is felt by object along y-axis.
