PRIN 2005 WOMEN Project Research unit: Università degli Studi di Napoli Federico II 5 th Meeting of WOMEN Project Trento, February 12, 2008 Fabio Sterle

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 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 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 D. Mattera, L. Paura, and F. Sterle, “MMSE WL equalizer in presence of receiver IQ imbalance,” to be published on Trans. Signal Process., April 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, 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 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.

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 IQ imbalance in RF systems

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Direct-frequency conversion The imperfections in the analog stage are due to low-cost fabrication technologies. (received signal) useful signalnoise Low-pass equivalent model LPF A/D Digital Signal Processor

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Direct-frequency conversion The imperfections in the analog stage are due to low-cost fabrication technologies. (received signal) useful signalnoise Low-pass equivalent model  y(t)= y c (t)+ j y s (t) coincides with r(t) only when  =0 and  =0.  the receiver IQ imbalance can be compensated if  and  are known. LPF A/D Digital Signal Processor

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 IQ imbalance in multicarrier system IFFT P/SS/P FFT Direct Down-Conversion (IQ imbalance) The OFDM system: The input signal of the DDC stage is:

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 IQ imbalance in multicarrier system The OFDM system: IFFT P/SS/P FFT Direct Down-Conversion (IQ imbalance)

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 IQ imbalance in multicarrier system The OFDM system: IFFT P/SS/P FFT Direct Down-Conversion (IQ imbalance)

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 IQ imbalance in multicarrier system The OFDM system: IFFT P/SS/P FFT Direct Down-Conversion (IQ imbalance) IQ distorsion or interference

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 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:

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 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.

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 MLE for Gaussian signal The transmitted signal is modeled as a Gaussian process. Likelihood function for unknown α and θ (N received samples): Cramèr-Rao Lower Bound (CRLB) 1) low computational complexity 2) robustness

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Numerical results: estimation Parameter setting: K is the number of received samples SNR  1/σ n 2 =25dB 64-QAM AWGN and Frequency Selective Channel (FCS) very near to the CRLBs

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Numerical results: SER vs. K Parameter setting: IQ mismatch α=0.1 (10%), θ=π/18 (10°) K is the number of received samples 64-QAM SNR  1/σ n 2 =25dB Existing method:

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Numerical results: IIR vs. K Parameter setting: K is the number of received samples SNR  1/σ n 2 =25dB 64-QAM Image Rejection Ratio ( IIR ):

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 DVB-T system Matlab Simulink to create a DVB-T environment.

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 IQ imbalance in DVB-T systems

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 IQ imbalance in DVB-T systems

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 IQ level estimation in DVB-T system

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 BER after decoding

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 MIMO Systems

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 MIMO system model Input-output equation of the LTI MIMO system:   non-dispersive channel

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 The linear DF MMSE equalizer The MIMO DF equalizer output: Feedforward-based equalizer: Successive-cancellations:

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 The linear DF MMSE equalizer The MIMO DF equalizer output: Feedforward-based equalizer: Multistage equalizer:

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Fast synthesis of DF equalizers The DF equalizer optimization reduces to a least-square problem under the assumption of uncorrelated input and noise: Multistage equalizer: Successive-cancellations: Feedforward-based equalizer:

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 F widely linear processing linear processing Widely linear processing (WL)

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Widely linear processing (WL) Question: When does the WL processing allow one to achieve a performance gain over the conventional linear processing? optimum

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 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 n r (0≤ n r ≤ N i ) 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.

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Multistage equalizers The following multistage equalizer structures have been considered: feedforward-based equalizer (FFB) successive-cancellations equalizer (SC) successive-cancellations BLAST equalizer (BLAST) multistage equalizer (MS) MS-SC multistage equalizer (MS) MS-BLAST multistage equalizer (MS) MS-PARALLEL

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Numerical results: SER vs. iter.

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Dynamic addressing-based routing scalable protocols for MANET

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 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.

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 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.

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Results Normalized packet delivery ratio versus the number of nodes.

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 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.

5 th Meeting of WOMEN Project – Research unit of Napoli Febr. 12, 2008 Thank you