Energy Efficiency of MIMO Transmissions in Wireless Sensor Networks with Diversity and Multiplexing Gains - PowerPoint PPT Presentation

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Energy Efficiency of MIMO Transmissions in Wireless Sensor Networks with Diversity and Multiplexing Gains

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Title: Energy Efficiency of MIMO Transmissions in Wireless Sensor Networks with Diversity and Multiplexing Gains


1
Energy Efficiency of MIMO Transmissions in
Wireless Sensor Networks with Diversity and
Multiplexing Gains
Wenyu Liu, Xiaohua (Edward) Li and Mo Chen
Department of Electrical and Computer
Engineering State University of New York at
Binghamton hyusa_at_hyig.com, xli,
mchen0_at_binghamton.edu, http//ucesp.ws.binghamton
.edu/xli
2
Abstract
  • Energy efficiencies of some MIMO transmission
    schemes in wireless sensor networks are analyzed
    considering the trade-off between diversity and
    multiplexing gains
  • Optimal energy efficiency requires both
    diversity and multiplexing gain
  • Cooperative MIMO are potential for enhancing
    energy efficiency

3
Outline
  1. Introduction
  2. MIMO Transmission Schemes
  3. Energy Efficiency of non-cooperative MIMO
  4. Energy Efficiency of cooperative MIMO
  5. Simulations
  6. Conclusions

4
  1. Introduction
  • Cooperative transmissions in sensor networks
    exploit the collaborative nature of sensors
  • Cooperative STBC to improve energy efficiency
    depending on transmission distance
  • Overheads
  • Circuitry energy consumption increases
  • Cooperation overhead reduces energy efficiency
  • Cooperative MIMO Is it better for energy
    efficiency?
  • Even higher overheads
  • There is a fundamental trade-off between the
    diversity gain and the multiplexing gain.

5
2. MIMO Transmission Schemes
  1. non-cooperative MIMO

Physical antenna array in Rx
Physical antenna array in Tx
b) one-side, half-cooperative MIMO
Physical antenna array in Rx
A cluster of sensors forming an virtual array at
Tx
6
c) two-side, cooperative MIMO
A cluster of sensors forming an virtual array at
Rx
A cluster of sensors forming an virtual array at
Tx
General Cooperative MIMO Description
Cooperative transmission The primary head sensor
first broadcasts to the secondary head sensors
the data to be transmitted. Then at the next time
slot, all the heads (the primary and secondary)
perform cooperative transmission.
Cooperative receiving All the secondary heads
forward their received signals to the primary
head, where the MIMO signal detection is
performed.
7
MIMO Signal Model
Mt x 1 transmitted Signal, zero mean, ss
Mr x Mt channel matrix
power adjuster
Mr x 1 AWGN, zero mean, sv
Mr x 1 received signal
The received signal-to-noise ratio (SNR) at each
antenna
8
3. Energy Efficiency of Non-cooperative MIMO
3.1, Transmission Energy Efficiency
Bit Error Rate
Transmission Date Rate
  • Diversity Gain Improve energy efficiency
  • Multiplexing Gain Achieve higher rate ? higher
    trans. power
  • Reduce
    time ? enhance energy efficiency

9
Trade off between dr and r for some MIMO schemes
10
Transmission Energy
Total data to be transmitted
Large scale path loss with exponent n
N/-logPe
Cs2v
Transmission energy depends on both diversity
gain dr and multiplexing gain r
11
Circuitry Energy
Circuit Energy Constant
Overall transmission and circuitry energies
12
Non Cooperative MIMO energy efficiency (Jtc/Ktc
109)
MtMr2, Pe0.001, n 2 and d 10
meters Et100pJ / 249 and Ec50 nJ
13
4. Energy Efficiency of Cooperative MIMO
With either cooperative or half-cooperative
MIMOs, there is energy consumption in
cooperative overhead.
Primary heads chooses Mt -1 secondary heads
Step 1
(Overhead is small, and can be skipped)
(Major overhead broadcasting of the N data bits)
14
Total Energy Consumption
The data rate of broadcasting from the primary
head to the secondary head
Scale factor due to the fact that the symbol
alphabet of broadcast may be different from
cooperative transmission
Signal noise ratio to broadcasting
15
Step 4
The Mr-1secondary heads
quantize their received samples, and transmit
them as new symbol sequences to the primary head,
where MIMO receiving is performed to recover the
original N bits
Composite result of quantization and symbol
mapping
16
Overall energy consumption of the cooperative
MIMO transmission
Overall energy consumption of the
half-cooperative MIMO transmission
The cooperative or half cooperative MIMO energy
efficiency can be optimized as
17
Cooperative MIMO energy efficiency (Ja/Ktc 109)
MtMr2, Pe0.001, n 2 and d 100 meters,
Et100pJ / 249 and Ec50 nJ
18
Half-cooperative MIMO energy efficiency (Jh/Ktc
109)
MtMr2, Pe0.001, n 2 and d 100 meters,
Et100pJ / 249 and Ec50 nJ
19
5. Simulation
Compare the simulated transmission energy
consumption with the theoretical values
20
6. Conclusion
  • Derived energy consumption representations for
    MIMO and cooperative MIMO
  • Cooperative overheads were considered in
    addition to transmission energy efficiency
  • The MIMO tradeoff between diversity and
    multiplexing was exploited for transmission
    energy efficiency optimization
  • MIMO and cooperative MIMO were shown beneficial
    to sensor network energy efficiency
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