Informatics Publishing Limited

Jaymin Bhalani ¹, Dharmendra Chauhan ¹, Y. P. Kosta ², A. I. Trivedi ³

Affiliations
1 Electronics and Communication Engineering Department, Charotar University of Science and Technology, Changa, IN
2 Marvadi Institute of Technology, Rajkot, IN
3 Electrical Engineering Department, M.S. University, Baroda, IN

Abstract

In this paper, we propose two novel semi-blind channel estimation techniques based on QR decomposition for Rayleigh flat fading Multiple Input Multiple output (MIMO) channel using different receiver antenna combinations and various pilot symbols. In the first technique, the flat-fading MIMO channel matrix H can be decomposed as a upper triangular matrix R and a unitary rotation matrix Q as H=RQ. The matrix R is estimated blindly from only received data by using orthogonal matrix triangularization based house holder QR decomposition, while the optimum rotation matrix Q is estimated exclusively from pilot based Orthogonal Pilot Maximum Likelihood Estimator (OPML) algorithm. In the second technique, joint semi-blind channel and data estimation is performed using QR decomposition based Least Square (LS) algorithm. Simulations have taken under 4-PSK data modulation scheme for two transmitters and different combinations of receiver antennas as well as various training symbols. Finally, these two new techniques compare with Whitening Rotation (WR) based semi-blind channel estimation technique and results shows that those new techniques achieve very nearby performance with low complexity compare to Whitening rotation based technique. Also first technique with perfect R outperforms Whitening Rotation based technique.

Keywords

Multiple Input Multiple Output, Orthogonal Pilot ML Estimator, QR Decomposition, Semi Blind Channel Estimation.

Full Text

     

Jaymin Bhalani ¹, Dharmendra Chauhan ¹, A. I. Trivedi ²

Affiliations
1 Electronics and Communication Engg. Department, Charotar University of Science and Technology, Changa, IN
2 Electrical Engg. Department, M.S. University, Baroda, IN

Abstract

In this paper, we present Orthogonal Pilot MaximumLikelihood (OPML) based MIMO (Multi Input Multi Output) semi-blind channel estimation technique for quasi-static Rayleigh fading channel. Channel matrix H can be decomposed as the matrix product of a whitening matrix W and the unitary matrix Q , from which W can be estimated blindly using singular value decomposition of received output data and Q can be estimated exclusively from training sequences using OPML algorithm. Simulations taken for 2 transmitters and 4, 6 and 8 receiver antennas combination and different modulation schemes such as BPSK, 4-PSK and 8-PSK. Result shows that BER improvements in 8 receiver antennas and BPSK modulation scheme outperform others.

Keywords

Multi Input Multi Output, Orthogonal Pilot ML Estimator, Semi Blind Channel Estimation.

Full Text

     

Dilip H. Patel ¹, Kiritkumar Bhatt ², Jaymin Bhalani ³

Affiliations
1 Department of Electronics and Communication Engineering, LDRP Institute of Technology and Research, IN
2 Department of Electronics and Communication Engineering, Sardar Vallabhbhai Patel Institute of Technology, IN
3 Department of Electronics and Communication Engineering, Babariya Institute of Technology, IN

Abstract

In Optical Burst Switched (OBS) Networks, data is transported in a bufferless network and hence there is fair amount of possibility of contention among the data bursts. This occurs when multiple bursts contend for the same link. The existing reactive contention resolution schemes attempt to address issue of contention without making any efforts to minimize the occurrences of contention in the network. Also, the existing proactive contention minimization schemes fail to provide improvement in contention loss at a very high load. Therefore, we are presenting new scheme for reducing the occurrence of contention in OBS network and it is known as Dynamic Hybrid Cluster and Deflection Feedback (DHCF) scheme. In proposed DHCF scheme entire OBS network is partitioned into many small clusters. In each cluster, one node acts as cluster head for gathering the information of resources in the network. The contention is minimized using clustering approach and it can be further improved with the help of deflection feedback mechanism. A performance metrics is considered to evaluate merits of the proposed DHCF scheme and its effects on overall network performance. Also, the comparison of the performance of the DHCF scheme with limited hybrid deflection and retransmission (LHDR) scheme and dynamic hybrid retransmission in deflection routing (DHRD) scheme is made. The simulation results show that the proposed scheme gives improvement in Burst Loss Probability (BLP) in the range of 31% to 38% and delay improvement in the range of 64% to 74% on vBSN network. The vBSN is network topology.

Keywords

Optical Burst Switching, Contention Resolution, Burst Loss Probability (BLP).

Full Text