Qualcomm Interview Questions, Process, and Tips

Test with 3 coding questions

Q1. Basic DP problem: use recursion and memoise it
Add your answer
Q2. Bit Manipulation
Add your answer

Q1. Merge Linked lists
Add your answer
Q2. Level Order Traversal
Add your answer

Q1. Behavioral round, discussion with hiring manager around experience
Add your answer

Q1. Multithreading, OS concepts, C, Cpp
Add your answer

Q1. Explain OFDM and need of CP
Ans. 
OFDM is a modulation technique that divides a high-speed data stream into multiple subcarriers. CP is added to prevent inter-symbol interference.
• OFDM stands for Orthogonal Frequency Division Multiplexing

• It is used in high-speed data transmission over wireless and wired networks

• OFDM divides the data stream into multiple subcarriers that are orthogonal to each other

• CP or Cyclic Prefix is added to each OFDM symbol to prev...read more
Answered by AI
Add your answer
Q2. Why wireless channel is modelled as Rayliegh
Ans. 
Rayleigh fading is a statistical model for the effect of a propagation environment on a radio signal.
• Rayleigh fading is a common model for wireless channels because it accurately represents the random fluctuations in signal strength caused by multipath propagation.

• It assumes that the signal is scattered by many objects in the environment, resulting in a large number of reflected signals arriving at the receiver with di...read more
Answered by AI
Add your answer

Q1. Derive optimal threshold for BPSK detection
Ans. 
Optimal threshold for BPSK detection can be derived using the likelihood ratio test.
• The threshold should be set such that the probability of false alarm is equal to the probability of detection.

• The threshold can be derived by finding the point where the likelihood ratio crosses a certain threshold value.

• The threshold can also be derived by maximizing the signal-to-noise ratio.

• Simulation and testing can be done to verif
Answered by AI
Add your answer
Q2. Explain relationship between coherence time and subcarrier spacing
Ans. 
Coherence time and subcarrier spacing are inversely proportional.
• Coherence time is the time duration over which a wireless channel remains constant.

• Subcarrier spacing is the frequency difference between adjacent subcarriers in an OFDM system.

• The coherence time and subcarrier spacing are inversely proportional to each other.

• If the subcarrier spacing is decreased, the coherence time increases and vice versa.

• This relation...read more
Answered by AI
Add your answer

Q1. What is cramer Rao's bound, explain
Ans. 
Cramer Rao's bound is a lower bound on the variance of any unbiased estimator of a parameter.
• It is used in statistical signal processing to determine the accuracy of parameter estimation.

• It is based on the Fisher information matrix, which measures the amount of information a random variable carries about a parameter.

• The bound is tight when the estimator is efficient, meaning it achieves the minimum variance possible.

• It...read more
Answered by AI
Add your answer
Q2. Questions on btech and mtech project
Add your answer

Q1. Design OFDM system for given scenario
Ans. 
Design an OFDM system for a given scenario.
• Determine the bandwidth and carrier frequency

• Choose the number of subcarriers and their spacing

• Select a suitable cyclic prefix length

• Implement modulation scheme and error correction coding

• Optimize system performance through simulation and testing
Answered by AI
Add your answer
Q2. Pdf of sum and max of two iid uniform rvs in the range 0 to 1
Ans. 
Pdf of sum and max of two iid uniform rvs in the range 0 to 1
• The sum of two uniform random variables is a triangular distribution

• The maximum of two uniform random variables is also a uniform distribution

• The joint pdf can be derived using convolution and differentiation

• The resulting pdf will have piecewise functions
Answered by AI
Add your answer

Q1. Explain coherence time, coherence bandwidth, delay spread and Doppler spread
Ans. 
Coherence time is the time duration over which a signal remains correlated. Coherence bandwidth is the frequency range over which a signal remains correlated. Delay spread is the time difference between the arrival of the first and last multipath components. Doppler spread is the frequency difference between the maximum and minimum Doppler shifts.
• Coherence time and coherence bandwidth are important parameters in wirele...read more
Answered by AI
Add your answer
Q2. What is the distribution of product of N normal RVs
Ans. 
The product of N normal RVs is a non-central chi-squared distribution with N degrees of freedom.
• The distribution is non-central chi-squared with N degrees of freedom

• The non-centrality parameter is the product of the means of the RVs

• The variance of the distribution is the product of the variances of the RVs

• This distribution is commonly used in signal processing and communication systems
Answered by AI
Add your answer

Q1. Past experience related
Add your answer

Q1. RTL Design related
Add your answer

Q1. FPGA Design related
Add your answer

Q1. Timing Analysis & Closure Related
Add your answer

Q1. Pay related, company culture etc
Add your answer

Q1. Technically what you are worked
Add your answer
Q2. Experience
Add your answer

Q1. Draw micro arch for given problem
Ans. 
Design a micro arch for a given problem
• Identify the specific problem that the micro arch needs to solve

• Consider the size and scale of the micro arch in relation to the problem

• Design the structure of the micro arch to efficiently address the problem

• Ensure that the materials used are suitable for the intended purpose
Answered by AI
Add your answer
Q2. Write verilog for the micro arch
Ans. 
Verilog code for micro architecture design
• Define modules for different components of the micro architecture

• Implement data paths and control logic using Verilog

• Use registers, multiplexers, and other logic gates to design the micro architecture

• Test the functionality of the micro architecture using simulation tools
Answered by AI
Add your answer

Q1. General problem solving approach
Add your answer