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Metya S.K.,Malaviya National Institute of Technology, Jaipur | Janyani V.,Malaviya National Institute of Technology, Jaipur | Modani S.G.,Malaviya National Institute of Technology, Jaipur | Najjar M.,SYSCOM Laboratory
Optical and Quantum Electronics | Year: 2013

Polarization mode dispersion (PMD) which is the time space varying nature of two parallel splitting rays polarized perpendicularly in single mode fiber, causes a serious problem in high bit rate transmission. We evaluated the PMD induced system penalty by means of simulations for Miller and Manchester signals under similar conditions and found that Miller is more tolerant to PMD than Manchester. © 2012 Springer Science+Business Media, LLC. Source


Laouini N.,SYSCOM Laboratory | Ben Hadj Slama L.,InnovCom Laboratory | Bouallegue A.,SYSCOM Laboratory
2012 9th International Conference on High Capacity Optical Networks and Enabling Technologies, HONET 2012 | Year: 2012

The Layered Belief Propagation L-BP algorithm is is a modified Belief Propagation BP algorithm, where the check nodes are divided in subgroups called layers and each iteration is broken into multiple sub-iterations. In this paper, we consider layered belief propagation decoding and propose an efficient variable node layering for decoding LDPC codes that performs well. We compare the performance of the first introduced LDPC decoding algorithm BP and Layered BP using check node layering with Layered BP using variable node layering in terms of bit error rate (BER). We show that the convergence for decoding LDPC codes is increasing by using a simple and efficient layering strategy. © 2012 IEEE. Source


Laouini N.,SYSCOM Laboratory | Ben Hadj Slama L.,InnovCom Laboratory | Bouallegue A.,SYSCOM Laboratory
International Conference on Multimedia Computing and Systems -Proceedings | Year: 2014

Layered decoding is well appreciated in Low-Density Parity-Check (LDPC) decoder implementation since it provides efficient and high-throughput implementation of LDPC decoders. Variable-Node Layered Belief Propagation (VL-BP) algorithm and their reduced-complexity derivatives for LDPC codes are presented. The VL-BP algorithm is a modification of Belief Propagation algorithm (BP), where the variable nodes are divided in subgroups called layers and each iteration is broken into multiple sub-iterations. Some simplifications can also be made to lower the complexity of both BP and CL-BP algorithms, and particularly the complexity of the check node update rule. In this paper, we consider Variable Node Layered BP (VL-BP) algorithm and propose an optimized min-sum VL-BP (MS VL-BP) algorithm for decoding LDPC code which has better performance not only from MS VL-BP algorithm but also from BP algorithm. In this decoding method, unlike other layered algorithms, we consider for the first layer a set of variable nodes that has a low value of the intrinsic information. Simulation results show that good performance can be achieved, and which can even be improved by the addition of either a normalization term or an additive offset term. © 2014 IEEE. Source


Laouini N.,SYSCOM Laboratory | Ben Hadj Slama L.,InnovCom Laboratory | Bouallegue A.,SYSCOM Laboratory
4th International Conference on Communications and Networking, ComNet 2014 - Proceedings | Year: 2014

Shuffled decoding is known to provide efficient and high-throughput implementation of LDPC decoders. In this paper, a new grouping technique of variable nodes to accelerate the message-passing rate is presented. In this algorithm, unlike other group-shuffled decoding methods, we consider for the first sub-group a set of variable nodes that has a low value of the intrinsic information, where the variable nodes of the code graph are divided into sub-groups called layers to perform group-by-group message-passing decoding and each iteration is broken into multiple sub-iterations. This paper proposes a simplification of the Variable Node group-shuffled Belief Propagation (Optimized VN group-shuffled BP) to lower the complexity of the check node update rule. Simulation results, verify that the Optimized VN group-shuffled BP does yield a faster convergence rate than both Belief Propagation (BP) and Check Node group-shuffled Belief Propagation (CN group-shuffled BP) decoder. © 2014 IEEE. Source


Hakimi W.,SYSCOM Laboratory | Ammar M.,SYSCOM Laboratory
2011 3rd International Conference on Next Generation Networks and Services, NGNS'2011 | Year: 2011

It is well known that HARQ technique generates delays du to the retransmissions. Thus, the high speed real time services quality, in High Speed Downlink Packet Access (HSDPA), depends on the number of the retransmissions. Motivated by the important diversity that multiple transmitting antennas and multiple receiving antennas (MIMO) can provide, we study the possibility to avoid HARQ retransmissions by using evolved detector as Multipath Parallel Interference Canceller (MPIC) associated to MIMO. Based on generalized Alamouti codes, then, we demonstrate that MIMO 44 MPIC detector could give better performance than MIMO 22 Space-time Rake taking into account the HARQ context. © 2011 IEEE. Source

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