CCS355 Neural Networks & Deep Learning Unit 1 PDF notes with Question bank .pdf
Ece mimo ppt
1. EC6801 WIRELESS COMMUNICATION
SYLLABUS
UNIT I WIRELESS CHANNELS
Large scale path loss – Path loss models: Free Space and Two-Ray models -Link Budget design –
Small scale fading- Parameters of mobile multipath channels – Time dispersion parameters
Coherence bandwidth – Doppler spread & Coherence time, Fading due to Multipath time delay spread
– flat fading – frequency selective fading – Fading due to Doppler spread – fast fading – slow fading.
UNIT II CELLULAR ARCHITECTURE
Multiple Access techniques - FDMA, TDMA, CDMA – Capacity calculations–Cellular concept
Frequency reuse - channel assignment- hand off- interference & system capacity- trunking & grade
of service – Coverage and capacity improvement.
UNIT III DIGITAL SIGNALING FOR FADING CHANNELS
Structure of a wireless communication link, Principles of Offset-QPSK, p/4-DQPSK, Minimum Shift
Keying, Gaussian Minimum Shift Keying, Error performance in fading channels, OFDM principle –
Cyclic prefix, Windowing, PAPR.
UNIT IV MULTIPATH MITIGATION TECHNIQUES
Equalisation – Adaptive equalization, Linear and Non-Linear equalization, Zero forcing and LMS
Algorithms. Diversity – Micro and Macrodiversity, Diversity combining techniques, Error
probability in fading channels with diversity reception, Rake receiver,
UNIT V MULTIPLE ANTENNA TECHNIQUES
MIMO systems – spatial multiplexing -System model -Pre-coding - Beam forming - transmitter
diversity, receiver diversity- Channel state information-capacity in fading and non-fading channels
2. EC 6801 WIRELESS COMMUNICATION
FIREST AND SECOND UNIT STUDY PROBLEMS ALSO
Unit I
1. Explain the time variant two-path model of a wireless propagation channel.
2. What is small scale fading? Explain the classification of wireless channels using
multipath delay spread and Doppler Spread.
3. Assume a receiver is located 10km from a 50W transmitter. If the carrier
frequency is 1900MHz, Gt =l,Gr=2, find the power at the receiver assuming a free
space propagation. Also determine the received power at the mobile using two ray
ground reflection model considering the transmitter antenna height as 50m,
receive antenna height as 1.5m above the ground and the ground reflection as – 1
4. Explain with mathematical equations two-ray path loss model.
5. Explain free space propagation model and derive the FRISS free space
equation gain expression
3. Unit II
1. Explain FDMA, TDMA and CDMA multiple access schemes
2. Discuss about the different types of interferences in wireless communication and ho
it can be minimized
3. With diagram explain a handoff (or) handover scenario at cell boundary. Compa
different types of handoff techniques
4. Explain the methods of increasing the capacity of wireless cellular networks.
5. A spectrum of 30 MHz is allocated to a wireless FDD cellular system whichuses two
kHz simplex channels to provide full duplex voice and control channels, compute th
number of channels available per cell if a system uses (a) four cell reuse (b) seven ce
reuse (c) 12-cell reuse. If 1 MHz of the allocated spectrum is dedicated to contr
channels, determine an equitable distribution of control channels and voice channe
in each cell for each of the three systems.
6. A mobile is located 2 km away from a base station and uses a vertical / 4 monopo
antenna with a gain of 2.55 dB to receive cellular radio signals. The E field at 1 k
from transmitter is measured to be 10-3 V/m. The carrier frequency used for th
system is 900 MHz. Determine the length and effective aperture of the receivin
antenna. Also, find the received power at the mobile using the two-ray groun
reflection model assuming the height of the transmitting antenna is 50 m and th
receiving antenna is 1.5 m above ground.
7. If a signal to interference ratio of 20dB is required for satisfactory forward chann
performance of a cellular system, what is the frequency reuse factor and cluster si
that should be used for maximum capacity if the path loss exponent is a) n = 4 b) n =3
Assume that there are 3 co-channel cells in the first tier and all of them are at the sam
distance from the mobile.
4. Unit III
1. Explain pi/4 QPSK , Offset QPSK and DQPSK with transmitter and receiver diagrams
comment on spectral efficiency
2.What is MSK? Explain with suitable diagrams the transmitter and receiver for MSK
modulation scheme.
3.Explain in detail about Gaussian Minimum Shift Keying (GMSK) Transmitter and
receiver with
4. Draw the basic arrangement of Orthogonal Frequency Division Multiplexing
transceivers and discuss its overall operation
5.A 900 MHz carrier signal is frequency modulated using a 100 kHz sinusoidal modulating
waveform. The peak deviation of the FM signal is 500 kHz. If this FM signal is received by a
superheterodyne receiver having an IF frequency of 5 MHz, determine the IF bandwidth
necessary to pass the signal
6.A zero mean sinusoidal message is applied to a transmitter that radiates an AM signal
with 10 kW power. Compute the carrier power if the modulation index is 0.6. What
percentage of the total power is in the carrier? Calculate the power in each sideband.
5. Unit IV
1. Explain (a)Spatial diversity (b), Temporal Diversity (c).Polarizationdiversity
(d).Macro diversity
2. Examine about the effects of multipath propagation on CDMA
3. With a neat block diagram, explain RAKE Receiver
4. Explain the operation an adaptive equalizer at the receiver side
5. discuss the decision feedback equalization
6. With diagram, explain Adaptive equalization techniques. Explain Least Mean
Square (LMS) algorithm
and Recursive LeastSquares (RLS) algorithmin detail
6. Unit V
1. With diagram, explain the system model for MIMO systems
2. Discuss about the operation of Spatial Multiplexing systems.
3. Derive the capacity of Non fading channel for information transmitted from a
wireless system
4. Derive the capacity of a fading channel for information transmitted from a wireles
system using waterfilling algorithm
Explain the operation of transmit precoding and receiver precoding schemes
7. Introduction
What is MIMO?
Spatial Diversity and Spatial Multiplexing
MEMO capacity on fading channels
Benefits of MIMO
Drawbacks of MIMO
Conclusion
8. MIMO Systems:
use multiple inputs and multiple outputs from
a single channel
are defined by Spatial Diversity and Spatial
Multiplexing
9. As we know MIMO is multiple antenna
technology in which more than one antennas
are used at transmitter and receiver stations.
10. Spatial Diversity
◦ Signal copies are transferred from multiple
antennas or received at more than one antenna
◦ redundancy is provided by employing an array of
antennas, with a minimum separation of λ/2
between neighbouring antennas
Spatial Multiplexing
◦ the system is able to carry more than one data
stream over one frequency, simultaneously
11. There is always a need for increase in performance
in wireless systems
◦ Significant increase in spectral efficiency and data
rates
◦ High Quality of Service (QoS)
◦ Wide coverage, etc.
Wireless channel that we are using is very
unfriendly
◦ Suffers from Co–channel interference and signal
level fading
◦ It provides a limited bandwidth
◦ power falls off with distance
12. By using Multiple Output Multiple Input (MIMO)
systems
◦ Diversity gain mitigates the fading and increases
coverage and improves QoS
◦ Multiplexing gain increases capacity and spectral
efficiency with no additional power or bandwidth
expenditure
◦ Array gain results in an increase in average
receive SNR.
Spatial Diversity and Spatial Multiplexing can be
conflicting goals
13. MIMO channels can be decomposed into a number of R
parallel independent channels → Multiplexing Gain
◦ Principle: Transmit independent data signals from different
antennas to increase the throughput, capacity.
14. The capacity increase can be seen by comparing MEMO
systems with SISO, SIMO, and MISO systems
◦ SISO:capacity is given by Shannon’s classical formula:
Where B is the BW and h is the fading gain
◦ SIMO (with M transmitting antennas), the capacity is given by
[2]
◦ MISO (with M transmitting antennas), the capacity is given by
[2]
)
2
1(
2
log hsnrBC
)
1
2
1(
2
log
m
n
n
hsnrBC
)
1
2
1(
2
log
N
n
n
h
N
snr
BC
15. The capacity for MIMO systems can have the following
forms (Assuming Tx antennas = Rx antennas = N):
A) If the channel is not known at the transmitter:
◦ Where Es is the total power, σ2 is noise level of AWGN
◦ Hence the power is equally shared by each channel
◦ The capacity grows linearly with the number of antennas
B) If the channel is known at the transmitter
)
2
2
1(
2
log
n
h
N
s
E
NC
N
n n
hn
E
C
1
)
2
2
1(
2
log
18. Improves the signal quality and achieves a higher SNR at the
receiver-side
Principle of diversity relies on the transmission of structured
redundancy
xi
yi
19.
20. ➨There is lower susceptibility of tapping by
unauthorized persons due to multiple antennas
and algorithms.
➨The systems with MIMO offers high QoS (Quality
of Service) with increased spectral efficiency and
data rates.
➨The wide coverage supported by MIMO system
helps in supporting large number of subscribers
per cell.
➨The MIMO based system is widely
21. ➨The hardware resources increase power
requirements. Battery gets drain faster due to
processing of complex and computationally
intensive signal processing algorithms. This
reduces battery lifetime of MIMO based devices.
➨MIMO based systems cost higher compare to
single antenna based system due to increased
hardware and advanced software requirements.
23. The capacity of Receive or Transmit Diversity grows
logarithmically with the number of antennas
Capacity of MIMO increases linearly with the number of
antennas
Using Spatial Diversity:
◦ The SNR increases and decreases when using MIMO
Spatial Multiplexing and Spatial Diversity are conflicting
objectives
