PRIN 2005 WOMEN Project Research unit: Universit

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PRIN 2005 WOMEN ProjectResearch unit
Università degli Studi di Napoli Federico II

• 5th Meeting of
• WOMEN Project
• Trento, February 12, 2008
• Fabio Sterle

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Outline

• IQ imbalance in RF systems
• Blind estimation of the receiver IQ imbalance
  parameters
• IQ imbalance in DVB-T systems
• MIMO systems
• Multistage DF MMSE equalizer synthesis
• Dynamic addressing-based routing scalable
  protocols for MANET
• Tree-based routing protocol

1. D.Mattera, F.Sterle, ML estimation of reciever
   IQ imbalance parameters, Third International
   Waveform Diversity Design Conference, Pisa
   (Italy), 4-8 June 2007.
2. M. Lipardi, D.Mattera, F.Sterle, MMSE
   Equalization in Presence of Transmitter and
   Receiver IQ Imbaclance, Third International
   Waveform Diversity Design Conference, Pisa
   (Italy), 4-8 June 2007.
3. D. Mattera, L. Paura, and F. Sterle, MMSE WL
   equalizer in presence of receiver IQ imbalance,
   to be published on Trans. Signal Process., April
   2008.
4. M. Caleffi, G. Ferraiuolo, L. Paura, Augmented
   Tree-based Routing Protocol for Scalable Ad Hoc
   Networks, IEEE Internatonal Conference on Mobile
   Adhoc and Sensor Systems (MASS '07), Pisa
   (Italy), 8-11 October, 2007.
5. M. Caleffi, G. Ferraiuolo, L. Paura, On
   Reliability of Dynamic Addressing Routing
   Protocols in Mobile Ad Hoc Networks, Proc. of
   Wireless Rural and Emergency Communications
   Conference (WRECOM '07), Roma (Italy), October
   2007.
6. M. Caleffi, G. Ferraiuolo, and L.Paura, A
   Reliability-based Framework for Multi-path
   Routing Analysis in Mobile Ad-Hoc Networks, to
   appear on International Journal of Communication
   Networks and Distributed Systems.

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• IQ imbalance in RF systems

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Direct-frequency conversion

• The imperfections in the analog stage are due to
  low-cost fabrication technologies.

Low-pass equivalent model
(received signal)
useful signal
noise
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Direct-frequency conversion

• The imperfections in the analog stage are due to
  low-cost fabrication technologies.

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IQ imbalance in multicarrier system

• The OFDM system

The input signal of the DDC stage is
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IQ imbalance in multicarrier system

• The OFDM system

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IQ imbalance in multicarrier system

• The OFDM system

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IQ imbalance in multicarrier system

• The OFDM system

IQ distorsion or interference
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IQ imbalance compensation

• The IQ imbalance at the receiver can be
  compensated provided that the IQ imbalance level
  is known
• In fact, it is easy verified that

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ML Estimation of the IQ parameters

• The IQ imbalance parameters are blindly estimated
  according to the maximum-likelihood (ML)
  criterion.
• Assumptions
• 1) The transmitted signal is circularly
  symmetric.
• 2) The noise is zero-mean white Gaussian
  circularly symmetric.

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MLE for Gaussian signal

• The transmitted signal is modeled as a Gaussian
  process.

Likelihood function for unknown a and ? (N
received samples)
1) low computational complexity 2) robustness
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Numerical results estimation

• Parameter setting
• K is the number of received samples
• SNR? 1/sn225dB
• 64-QAM
• AWGN and Frequency
• Selective Channel (FCS)

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Numerical results SER vs. K

• Parameter setting
• IQ mismatch a0.1 (10), ?p/18 (10)
• K is the number of received samples
• 64-QAM
• SNR? 1/sn225dB
• Existing method

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Numerical results IIR vs. K

• Parameter setting
• K is the number of received samples
• SNR? 1/sn225dB
• 64-QAM
• Image Rejection Ratio (IIR)

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DVB-T system

• Matlab Simulink to create a DVB-T environment.

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IQ imbalance in DVB-T systems
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IQ imbalance in DVB-T systems
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IQ level estimation in DVB-T system
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BER after decoding
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• MIMO Systems

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MIMO system model

• Input-output equation of the LTI MIMO system

non-dispersive channel
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The linear DF MMSE equalizer

• The MIMO DF equalizer output

Feedforward-based equalizer
Successive-cancellations
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The linear DF MMSE equalizer

• The MIMO DF equalizer output

Feedforward-based equalizer
Multistage equalizer
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Fast synthesis of DF equalizers

• The DF equalizer optimization reduces to a
  least-square problem under the assumption of
  uncorrelated input and noise

Feedforward-based equalizer
Successive-cancellations
Multistage equalizer
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Widely linear processing (WL)
F
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Widely linear processing (WL)

• Question When does the WL processing allow one
  to achieve a performance gain over the
  conventional linear processing?

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The WL DF MMSE equalizer

• The WL DF equalizer employs both a WL feedforward
  filter and a WL feedback filter to exploit the
  non-circular properties of the signals to be
  processed.

By assuming that nr (0nrNi) components of x are
real-valued, the MIMO channel input-output
equation can be rewritten as follows
The WL DF equalization is defined as the DF
equalization operating on the new channel model.
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Multistage equalizers

• The following multistage equalizer structures
  have been considered

feedforward-based equalizer (FFB)
multistage equalizer (MS) MS-PARALLEL
successive-cancellations equalizer (SC)
multistage equalizer (MS) MS-SC
successive-cancellations BLAST equalizer (BLAST)
multistage equalizer (MS) MS-BLAST
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Numerical results SER vs. iter.
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• Dynamic addressing-based routing scalable
  protocols for MANET

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Presentation of the activity

• Scope
• To single out scalable routing protocols able to
  face with the dynamic topology of MANET.
• Approach
• Dynamic Addressing.
• Goal
• To sepatate the unique terminal identifier, with
  no location information in a mobile network, from
  the routing address, which embeds a topological
  information.

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Implementation

• Address Allocation distributed mechanism able to
  assign to nodes an address which reflects the
  node relative position, without resorting to
  flooding.
• Routing proactive hierarchical multi-path
  protocol, able to explore multiple paths towards
  a destination with a limited overhead.
• Address lookup distribuited hash-based service
  (DHT) for providing the mapping between node
  identifier and routing address.

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Results

• Normalized packet delivery ratio versus the
  number of nodes.

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Conclusions

• IQ imbalance in RF systems
• The blind estimation of the receiver IQ
  parameters has been addressed.
• The effects of IQ imapairments in DVB-T systems
  has been presented.
• MIMO systems
• The DF equalizer design has been re-examined in
  terms of the conventional least-square problem.
• The WL processing has been combined with the DF
  strategy to exploit the properties of
  rotationally variant signals.
• Three multistage DF equalizer structures have
  been compared.
• Routing protocols for MANET
• An augmented tree-based routing protocol has been
  proposed to handle scalable ad-hoc networks.

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• Thank you