apwc _2
TRANSCRIPT
![Page 1: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/1.jpg)
Massive MIMO
Mustafa KhaleelKareem AA Difar
Alnaser Zaid
![Page 2: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/2.jpg)
Contents
MIMO Single user MIMO & Multi-user MIMO What is Massive MIMO ? Massive MIMO Key Features Critical Issues and Solutions TDD and FDD Pilot Contamination Pilot Open-Loop Power Control Facts
![Page 3: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/3.jpg)
MIMO MIMO (multiple input, multiple output) is an
antenna technology for wireless communications in which multiple antennas are used at both the source (transmitter) and the destination (receiver)
![Page 4: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/4.jpg)
Single user MIMO & Multi-user MIMO SU-MIMO: the data of a single user is
transmitted simultaneously on several parallel data streams (All streams to one user )
MU-MIMO : the individual streams are assigned to various users (Larger diversity gain than single user MIMO)
![Page 5: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/5.jpg)
What is Massive MIMO ?
A very large antenna array at each base station
A large number of users are served simultaneously
![Page 6: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/6.jpg)
Massive MIMO Key Features
Benefits from the (many) excess antennas
Differences with MU MIMO in conventional cellular systems
Main benefits:
huge spectral efficiency and high reliability
high energy efficiency
![Page 7: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/7.jpg)
Critical Issues
Gains are not that big with not-so-many antennas
Massive MIMO seems to be more “uplink driven”
Practical effects are not well investigated
![Page 8: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/8.jpg)
Solutions Wireless Communication suffers from attenuation in signal strength and
Interference between users and MIMO is well Known solution against Massive MIMO promises additional advantage over standard solutions.
SNR=(\\h\\2 *σ2m )*M/ σ2n
M is number of elements antenna . Shannon theorem Capacity (bits/sec )= Available spectrum (Hz)*spectral efficiency(dB)Where C is known as capacity of channel, B is known as bandwidth of the signal, S/N is known as signal to noise ratio. MT is the number of antennas used at the transmitter side & MR is the number of antennas used at receiver side.
![Page 9: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/9.jpg)
Expression related to Massive MIMO
![Page 10: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/10.jpg)
We need a pilot signal for Channel state information (CSI) estimation , but there are two problems
First, optimal downlink pilots should be mutually orthogonal between the antennas. This means that the amount of time frequency resources needed for downlink pilots scales as the number of antennas, so a massive MIMO system would require up to a hundred times more such resources than a conventional system.
Second, the number of channel responses that each terminal must estimate is also proportional to the number of base station antennas. Hence, the uplink resources needed to inform the base station about the channel responses would be up to a hundred times larger than in conventional systems [1] [4].
The solution is to operate in TDD mode, and rely on reciprocity between the uplink and downlink channels [1]
A:TDD operation is better than FDD in Massive MIMO because in TDD we need
TDD and FDD
![Page 11: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/11.jpg)
Pilot Contamination Pilot :signals from resources are used for synchronization and equalization
How we eliminate the interference btw users?
Techniques to Mitigate Pilot Contamination
Pilots are used to estimate the channel state information
1 .Pilot Open-Loop Power Control2 .Less Aggressive Pilot Reuse
3 .Soft Pilot Reuse
![Page 12: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/12.jpg)
Pilot Open-Loop Power Control
a pilot open loop power control (pilot OLPC) scheme that allows the terminal to adjust the transmit power of its pilot signal .based on its estimate of the pathloss to its serving BS
![Page 13: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/13.jpg)
Less Aggressive Pilot Reuse Pilot reuse is analogous to the traditional frequency reuse in the
sense that terminals within the pilot reuse area can utilize only a fraction of the time-frequency resources, during the channel estimation phase.
The pilot reuse factor 1/U is the rate at which pilot resources may bereused in the network, where U is the number of cells that are assigned orthogonal pilots .
Pilot reuse
![Page 14: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/14.jpg)
Soft Pilot Reuse
assign additional orthogonal pilot resources to cell-edge terminals, with reuse factor 1/UE .
total pilot resources spent on cell-edge terminals is therefore · UE. pilot transmission by the rest of the terminals is (1 − ρ)K · U .
![Page 15: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/15.jpg)
mmWave and massive MIMO in cellular Directivity of massive MIMO compensates for high mmWave
attenuation, reduces multipath and multiuser interference. mmWave frequencies reduce the size required for massive MIMO
antenna arrays.
Massive MIMO testbed, Lund University, 2014
![Page 16: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/16.jpg)
Facts
1.Distributed network densification is preferable over massive MIMO if the average throughput per UT should be increased.
2.More antenna increase the coverage probability ,but more BSs lead to linear increase in the area spectral efficiency.
3 .If the cell radius will be decreased the data rate will increase and the users can be increased. Because the pilot contamination is decreased.
4.Massive MIMO uses spatial-division multiplexing such that the different data streams occupy the same frequencies and time.
5 .we can not increase the number of Antennas exponentially because the time spent acquiring CSI which grows with both the number of service antennas and the number of users.
6 .An advantage of matched filtering and conjugate beamforming is that the Massive MIMO signal processing can be performed locally at each antenna, . This in turn permits a decentralized architecture for the antenna array, which lends great resilience to the system. For example, if half the antennas are lost from a lightning strike, the remaining antennas do exactly what they did before. Likewise, during periods of slack demand, some antennas can be put into sleep mode, for improved energy efficiency, without affecting the operations of the others.
7 .Massive MIMO a scalable technology: any number of base station antennas can be usefully employed with no tightening of array tolerances. Extra antennas always help. Ins contrast, if an assumed channel response is used the technology is ultimately not scalable.
![Page 17: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/17.jpg)
References
1.Division of Communication Systems Department of Electrical Engineering (ISY) Linköping University, SE-581 83 Linköping, Sweden
www.commsys.isy.liu.s 2.Nimay Ch. Giri1, Anwesha Sahoo2, J. R. Swain3, P. Kumar4, A. Nayak5, P.
Debogoswami6 Lecturer, Department of ECE, 2,3,4,5,6B.Tech Scholar, Centurion University of Technology and Management, Odisha, India
3.http://www.researchgate.net/post/What_is_the_acheivable_Massive_MIMO_capacity(Emil Björnson)
4.http://www.hindawi.com/journals/ijap/2014/848071/ 5.https://www.youtube.com/watch?v=zhncADqR9rg 6.Thomas L. Marzetta heads the LargeScale Antenna Systems Group in the Network Energy Program at Bell Labs in Murray Hill 7.https://www.youtube.com/watch?v=imLiaLQGmB8
![Page 18: APWC _2](https://reader035.vdocuments.us/reader035/viewer/2022062900/58ea58e91a28abb8208b567f/html5/thumbnails/18.jpg)
Thank you