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  Physical-layer security  
   


We were the first to propose physical-layer key generation for FDD wireless and power-line systems. The first is based on the reciprocity of Angles-of-Arrival and Angles-of-Departure, the latter on reciprocity of general passive two-ports. Random key are ensured by the wireless channel itself or permutations and reactive terminations at bridge taps or unused pairs, respectively. Furthermore, we designed key reconciliation schemes based on LDPC Slepian-Wolf coding and quantization grid adjustment.

         
  Joint source-channel coding  
 
We focus on the design of joint Tanner graphs for source and channel coding for sources with memory. Dependencies from a Markov model are treated as further a-priori information linking variable nodes. Furthermore, we join source and channel polarization for combined source-channel coding.





 

  Nonstationary interference treatment  
   


We investigate nonstationary disturbances in wireline and wireless systems. In wireline, we make us of the common-mode signal to cancel impulse noise from the differential mode or use the common mode to forecast error positions.
In wireless, we model impulse noise on antenna arrays caused by ignition, electical machines, MRI equipment, and alike. Furthermore, we determine detection and decoding schemes under impulse noise.

         
  DSL, Power-Line Communication, DMT, OFDM  
 
Work in DSL and Power-Line Comm. focuses on problems of multicarrier transmission, like PAR reduction, time-domain equalization, bit-allocation, noise suppression, ... . To name just a few outcomes of this research:
-  First real capacity optimizing time-domain equalizer
-  PAR reduction scheme which is widely used (many million installations)
-  A bit-allocation scheme allowing for arbitrary SNR margins between priority classes
-  First MIMO-DMT proposal based on singular-value decomposition
-  Noise cancellation in DSL and power-line comm.
-  Communication scheme over DC power liens.
-  Multi-line fully automatic 24-pair cable measurement tool (ftw.)





 

  Unequal error protecting codes  
   


We designed UEP Turbo and LDPC codes based on puncturing and pruning. In Turbo codes, pruning and puncturing with time-varying patterns allow for easy variation of the rate and gain. UEP LDPC codes were designed based on a irregular check profile. The applied pruning procedure allowed rate and gain adaptation according to given requirements.
UEP coded modulation is designed following the capacities at different partition levels at different signal-to-noise ratios.

         
  Analog codes and iterative decoding  
 
We found that the iterative decoding of analog concatenated codes may be described as iterative projections realizing a least-mean-square solution. This allows for a very intuitive understanding of the iterative Turbo-like decoding procedures.
Furthermore, we investigate the correction of bursty noise in additional background noise.





 

  UEP network coding and routing  
   


Network codes as a means of reducing the usage of links in a multicast scenario ask for different protection, since error propagation to the end node depends on error locations. Additionally, user data is of different importance and sensitivity. Both ask for suitable coding schemes combining aspects of rate-less and network codes. <\br> Different QoS levels (priorities) can be handled by suitable routing algorithms. We investigate routing in the context of cross-layer design and scalable video and audio information as well as in the context of Ad-Hoc network scenarios.

         
  MIMO and Multiuser Communication  
 
Our MIMO research focuses on the treatment of imperfect channel information and a possible realization of UEP properties just as in the case of multicarrier transmission.
We consider multi-user bit loading, multi-user hierarchical modulation, LDPC coded hierarchical modulation.





 

  Acoustical data transmission  
   


We investigate the properties of acoustical wave guides, especially water pipes. The goal will be low-rate data communications for control purposes.

         
  The code of life  
 
In a joint project with life sciences, we investigate the communications and code properties of the DNA. Our share deals with reasoning of the codon/aminoacid encoding structure, the error-protection, and source coding properties, whereas Prof. Mushelishvili's group concentrates more on the influences of the three dimensional orientation leading to analog control mechanisms in gene expression.