Sairamesh Nammi

A list-based detection technique for long intersymbol interference channels

A list based data detection algorithm is presented for long intersymbol interference channels. The algorithm first extracts bit reliabilities using a low complexity equalizer and then uses these reliabilities to generate lists of possible data vectors before making final bit decisions. It is shown through analysis that the detector can be designed to ensure a specific bit error rate performance with respect to a maximum likelihood sequence detector. The complexity advantage of the detector is described through analysis and simulation.

Distributed Alamouti Transmit Diversity Technique for Co-Operative Communications

A simple algorithm to implement a distributed version of the Alamouti diversity scheme is presented and its performance is studied. It is observed that the algorithm provides quick convergence, and a bit error rate (BER) performance quite close to the Alamoutis original localized scheme. The proposed algorithm has potential applications in providing diversity in co-operative communications, in poor scattering environments, and in hybrid channels consisting of optical and radio links.

Iterative List Subset Detectors for Turbo Product Coded MIMO Wireless Systems

Iterative detectors based on subset selection of candidate codewords are presented for turbo MIMO systems. The performance of the detectors is studied using turbo product codes as the constituent channel code. The proposed detectors are shown to perform close to capacity limits. They have low implementation complexity, and are able to outperform the existing detectors including the list sphere detector.

Threshold list subset detector for turbo MIMO systems

A threshold based list detector is presented for multiple-input multiple-output (MIMO) system. The detector is based on subset-sum algorithm. The algorithm make use of a low complexity sub optimal minimum mean square error (MMSE) detector to find the bit reliabilities, and uses these reliabilities to generate list of possible candidate data vectors. It is shown through analysis that this detector can be designed to ensure a specific bit error performance with respect to the optimum maximum likelihood detector. The proposed threshold list subset sum detector (T-LSS) is extended for coded turbo MIMO transmission. Unlike other detectors proposed in the literature, the T-LSS detector generates list for each outer iteration.

A concatenated space-time transmit diversity system with a class of high-rate low complexity channel codes

The concatenation of a multidimensional parity check code (MDPC) with space time block codes (STBC) is considered. An approximate expression for the bit error rate of the concatenated system is derived. Effects of imperfect channel estimation on the performance of the system is considered. A comparison with turbo convolutional code (TCC)-STBC system is presented. The error performance of MDPC-STBC system is found to be close to TCC-STBC system but with significantly low complexity.

Effects of impulse noise on the performance of multidimensional parity check codes

This paper investigates the effects of impulse noise on the performance of multidimensional parity check codes (MDPC) in additive white Gaussian noise and Rayleigh fading channels. The Bhattacharya upper bound is derived for impulsive noise and is found to closely match with the simulation results. It is observed that impulse noise can degrade the bit error rate performance by several dBs. Further, the use of incorrect impulse noise model in the receiver decoding algorithm is found to cause severe penalty in fading channels. Our results also show that MDPC codes outperform traditional convolutional codes in impulsive noise channels. The performance of MDPC codes is found to be slightly inferior to turbo codes, when the latter uses slightly lower code rate and higher complexity. The capacity limits for impulsive noise channels are also calculated