On Construction of Optimal A^2-Codes

Two authentication codes with arbitration (A 2 codes) are constructed from finite affine spaces to illustrate for the first time that the information theoretic lower bounds for A 2 codes can be strictly tighter than the combinatorial ones. The codes also illustrate that the conditional combinatorial lower bounds on numbers of encodingdecoding rules are not genuine ones. As an analogue of 3 dimensional case, an A 2 code from 4 dimensional finite projective spaces is constructed, which meets both the information theoretic and combinatorial lower bounds.

Blind Decorrelating Detection Based on Particle Swarm Optimization under Spreading Code Mismatch

A way of resolving spreading code mismatches in blind multiuser detection with a particle swarm optimization （PSO） approach is proposed. It has been shown that the PSO algorithm incorporating the linear system of the decorrelating detector, which is termed as decorrelating PSO （DPSO）, can significantly improve the bit error rate （BER） and the system capacity. As the code mismatch occurs, the output BER performance is vulnerable to degradation for DPSO. With a blind decorrelating scheme, the proposed blind DPSO （BDPSO） offers more robust capabilities over existing DPSO under code mismatch scenarios.

Optimal Asymmetric Quantum Codes from the Euclidean Sums of Linear Codes

In this paper,we first give the definition of the Euclidean sums of linear codes,and prove that the Euclidean sums of linear codes are Euclidean dual-containing.Then we construct two new classes of optimal asymmetric quantum error-correcting codes based on Euclidean sums of the Reed-Solomon codes,and two new classes of optimal asymmetric quantum error-correcting codes based on Euclidean sums of linear codes generated by Vandermonde matrices over finite fields.Moreover,these optimal asymmetric quantum errorcorrecting codes constructed in this paper are different from the ones in the literature.

EXIT analysis of M-algorithm based MIMO detectors and LDPC code design optimization

This paper investigates joint design and optimization of both low density parity check （LDPC） codes and M-algorithm based detectors including iterative tree search （ITS） and soft-output M-algorithm （SOMA） in multiple-input multiple-output （MIMO） systems via the tool of extrinsic information transfer （EXIT） charts. First, we present EXIT analysis for ITS and SOMA. We indicate that the extrinsic information transfer curves of ITS obtained by Monte Carlo simulations based on output log-likelihood rations are not true EXIT curves, and the explanation for such a phenomenon is given, while for SOMA, the true EXIT curves can be computed, enabling the code design. Then, we propose a new design rule and method for LDPC code degree profile optimization in MIMO systems. The algorithm can make the EXIT curves of the inner decoder and outer decoder match each other properly, and can easily attain the desired code with the target rate. Also, it can transform the optimization problem into a linear one, which is computationally simple. The significance of the proposed optimization approach is validated by the simulation results that the optimized codes perform much better than standard non-optimized ones when used together with SOMA detector.

Codes cross-correlation analysis and data/pilot code pairs optimization for Galileo E1 OS and GPS L1C

The Galileo E1 open service （OS） and the global positioning system （GPS） L1C are intending to use the multiplexed binary offset carrier （MBOC） modulation in E1/L1 band, including both pilot and data components. The impact of data and pilot codes cross-correlation on the distortion of the discriminator function （i.e., the S-curve） is investigated, when only the pilot （or data） components of MBOC signals are tracked. It is shown that the modulation schemes and the receiver configuration （e.g., the correlator spacing） strongly affect the S-curve bias. In this paper, two methods are proposed to optimize the data/pilot code pairs of Galileo E1 OS and GPS L1C. The optimization goal is to obtain the minimum average S-curve bias when tracking only the pilot components a the specific correlator spacing. Figures of merit, such as S-curve bias, correlation loss and code tracking variance have been adopted for analyzing and comparing the un-optimized and optimized code pairs. Simulation results show that the optimized data/pilot code pairs could significantly mitigate the intra-channel codes cross-correlation, and then improve the code tracking performance of MBOC signals.

Two Constructions of Optimal Cartesian Authentication Codes from Unitary Geometry over Finite Fields

Two constructions of cartesian authentication codes from unitary geometry are given in this paper. Their size parameters and their probabilities of successful impersonation attack and successful substitution attack are computed. They are optimal under some cases.

The Existence of (v,4,1) Disjoint Difference Families with a Prime Power

A （v, k, λ） difference family （（v, k, λ）-DF in short） over an abelian group G of order v, is a collection F=（Bi｜i ∈ I} of k-subsets of G, called base blocks, such that any nonzero element of G can be represented in precisely A ways as a difference of two elements lying in some base blocks in F. A （v, k, λ）-DDF is a difference family with disjoint blocks. In this paper, by using Weil＇s theorem on character sum estimates, it is proved that there exists a （p^n, 4, 1）-DDF, where p = 1 （rood 12） is a prime number and n ≥1.