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Signal Design and Its Applications in Communications, 2007. IWSDA 2007. 3rd International Workshop on

Date 23-27 Sept. 2007

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Displaying Results 1 - 25 of 89
  • New Direction of Wireless Technology

    Page(s): 1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1034 KB) |  | HTML iconHTML  

    The 3rd generation (3G) mobile wireless communications systems based on direct-sequence code division multiple access (DS-CDMA) technique were put into services, with much higher data rates than the present 2G systems, in many countries and their deployment speed has since accelerated. 3G systems will be continuously evolving with high speed downlink packet access (HSDPA) technique, multiple-input/multiple-output (MIMO) antenna technique, etc, for providing packet data services of around 14 Mbps as the mid-term evolution and of 50~100 Mbps as the long-term evolution. However, the capabilities of 3G wireless networks will sooner or later be insufficient to cope with the increasing demands for broadband services. The evolution of 3G systems will be followed by the development of 4G systems, that support extremely high-speed packet data services of e.g., 100 M~1 Gbps. The most important technical challenge for the realization of 4G systems is two-fold: (a) to overcome the severely frequency-selective fading channel, and (b) to significantly reduce the transmit power from mobile terminals. Frequency-domain equalization (FDE) can take advantage of channel frequency-selectivity and improve the transmission performance of single carrier (SC) DS-CDMA signal transmissions as well as multicarrier (MC) signal transmissions. MIMO can also be combined with FDE in SC transmission. Frequency-domain signal processing is believed to play an important role in 4G systems. Either SC or MC, both with FDE, can be used for the downlink (base-to-mobile) to achieve almost the same transmission performance. However, for the uplink (mobile-to-base) applications, SC transmission with FDE is more appropriate since it requires less peak transmit power. Transmit power reduction is a very important issue. Applying wireless multi-hop technique or distributed antenna technique is a possible solution to this issue. In this presentation, we will discuss about some important 4G wireless tech- niques. View full abstract»

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  • An algorithm for the k-error linear complexity of a sequence with period 2pn over GF(q)

    Page(s): 104 - 108
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB) |  | HTML iconHTML  

    We first optimize the structure of the Wei-Xiao-Chen algorithm for the linear complexity of sequences over GF(q) with period N = 2pn, where p and q are odd primes, and q is a primitive root ( mod p2). Then the union cost is used, so that an efficient algorithm for computing k-error linear complexity of a sequence with period 2pn over GF(q) is derived, where p and q are odd primes, and q is a primitive root of modulo p2. We also give a validity proof of the proposed algorithm. Finally, a numerical example is presented to illustrate the algorithm. View full abstract»

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  • A Security Video Watermarking Scheme for Broadcast Monitoring

    Page(s): 109 - 113
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1920 KB) |  | HTML iconHTML  

    Identification and verification of a video clip via its fingerprint find applications in broadcast monitoring, database search and transaction tracking. For broadcast monitoring, we propose a novel robust hashing algorithm for video based on the 3-D wavelet transform (3D-DWT). Then the watermark information and the short fingerprint using the proposed hash algorithm are combined to create the embedding information. On the base of the video hashing, a security video watermarking scheme is proposed for broadcast monitoring. Finally, the security of proposed algorithm is analyzed. Some experimental results, which prove the effectiveness of the algorithms, are presented. View full abstract»

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  • On Shift Bound for Cyclic Codes by DFT with Unknown Elements

    Page(s): 114 - 117
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (262 KB) |  | HTML iconHTML  

    The shift bound is a good lower bound of the minimum distance for cyclic codes, Reed-Muller codes and geometric Goppa codes. In this paper we consider cyclic codes defined by defining sequence and new simple derivation using the discrete Fourier transform with unknown elements and the Blahut theorem is shown. Moreover two examples of binary cyclic codes are given. View full abstract»

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  • Consideration of fast simulation technique of LDPC code

    Page(s): 118 - 122
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3181 KB) |  | HTML iconHTML  

    This paper proposes a method to estimate bit-error rate (BER) at high signal-to-noise ratio. The computer simulation result of the proposed method shows good agreement with those of the original Monte Carlo (MC) simulations. By using the proposed method, the number of bits needed to computer simulation is reduced to 50% of the MC simulation for code length 1027[bit], It is reduced to 20% compared with the MC simulation for code length 4000[bit], The time to estimate BER for the proposed method is reduced to 60% of original envelop method. View full abstract»

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  • On the Existence of Multilevel Hadamard Matrices with Odd Order

    Page(s): 123 - 127
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4498 KB) |  | HTML iconHTML  

    The multilevel (n-ary) Hadamard matrices, which are related to orthogonal matrices or orthogonal designs, are investigated in this paper. It is assumed that all matrix elements are integers, which make the binary Hadamard matrices as special cases of multilevel (n-ary) Hadamard matrices. It is shown that the multilevel Hadamard matrices of odd order do exist if only two different matrix elements are contained; but, except an unknown case, multilevel (n-ary) Hadamard matrices of odd order do not exist when all matrix elements are successive integers. View full abstract»

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  • Quotient Subcode Set and Inverse Relative Dimension/Length Profile

    Page(s): 128 - 132
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB) |  | HTML iconHTML  

    The generalized hamming weight played an important role in coding theory. In the study of the wiretap channel of type II, the generalized hamming weight was extended to a two-code format. Two equivalent concepts of the generalized hamming weight hierarchy and its two-code format, are the inverse dimension/length profile (IDLP) and the inverse relative dimension/length profile (IRDLP), respectively. In this paper, the relations between the IDLP and the IRDLP are investigated. By using a quotient subcode set, the singleton bound on the IRDLP is improved by different methods. The new bounds are useful for the study of a coordinated two-party wiretap channel of type II. View full abstract»

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  • AOA Estimation Based on MP Algorithm in Beam-Space Using Rotational Invariance Technique

    Page(s): 13 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3966 KB) |  | HTML iconHTML  

    A novel algorithm using Rotational Invariance technique for AOA estimation is presented in this paper, which is based on sparse decomposition of signal, and applied into beam-space against the deficiencies of traditional DF algorithms and sub-space algorithms. The former methods are widely used in actual applications. However, they have many drawbacks such as low-resolution, bad robustness and etc. The latter ones which base on subspace method have gained great interest in the past two decades. What we know about this kind of methods are their super-resolution quality and their weaknesses as well, e.g. constrained by the number of elements, behaving badly when correlativity of sources grows. Approach proposed in this paper fist constructs atom-dictionaries using outputs of second sub-array and then transforms observations of fist sub-array and dictionaries in array-space to beam-space, and finally obtains AOAs through thinning sectors by solving least squares problems. Numerical simulations have proved the effectivity of the algorithm and good performance in low signal-to-noise ratio (SNR) regime. View full abstract»

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  • An Improved Genetic Algorithm for QOS Multicast Routing

    Page(s): 133 - 137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3580 KB) |  | HTML iconHTML  

    Aiming at the problem of multicast routing with multiple QoS constraint, such as delay, bandwidth, losing rate, a new genetic algorithm is brought up based on the k-th shortest path in this paper. Our algorithm outputs an approximate Steiner tree satisfying all QoS constraint of multicast request in a network with e edges and v vertices, in time O(e+vlogv+kv). Under the genetic algorithm we proposed, a set of new methods in coding, crossover and mutation operation are also introduced which effectively improving the convergence of the genetic algorithm. View full abstract»

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  • Optimal Bit and Power Allocation Algorithm in Multi-Carrier CDMA

    Page(s): 138 - 142
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4646 KB) |  | HTML iconHTML  

    Multi-carrier code division multiple access (MC-CDMA) is a promising candidate for the air interface of 4G wireless networks. In MC-CDMA systems, a number of sub carriers per user are used for the high-rate data transmission, and each data modulated by a different sub earlier is transmitted through a different frequency band. Each data undergoes a different channel condition and arrives with a different error rate at the base station. By transmitting message data based on the channel state information (CSI), a new data transmission scheme called "optimal bit and power allocation algorithm in multi-carrier CDMA" is introduced in this paper. Simulated results have shown that the scheme yields a higher system capacity than a conventional MC-CDMA. View full abstract»

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  • Security of GPT-like public-key cryptosystems based on linear rank codes

    Page(s): 143 - 147
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (389 KB) |  | HTML iconHTML  

    Recent structural attacks on the GPT cryptosystem and variants are reviewed. The equivalency of different forms of cryptosystems is shown and the general form for the purpose of cryptanalysis is stated. The published structural attacks are turned out to be either polynomial, or exponential, depending on parameters of the cryptosystem. The secure choice of parameters is suggested for avoiding polynomial attacks. View full abstract»

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  • A Full Diversity, High Rate Space-time Block Coding Scheme

    Page(s): 148 - 151
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2157 KB) |  | HTML iconHTML  

    A novel space-time block coding (STBC) scheme for four transmit antennas is proposed based on the binary phase shift keying (BPSK) constellation modulation. The new scheme achieves full diversity full rate. And it also can achieve linear decoding at receiver, so the decoding complexity at receiver is greatly reduced. Because the scheme can achieve full diversity, good performance can be obtained not only at low signal to noise ratio (SNR) but also at high SNR. To improve the code rate further, we proposed a space-time spreading code. The space-time spreading code can achieve higher code rate without performance loss. View full abstract»

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  • New Efficient Check Node Update Method for Improved Min-Sum LDPC Decoding

    Page(s): 152 - 156
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3236 KB)  

    This paper has presented various min-sum related LDPC decoding algorithms and their typical hardware architectures of check node update in the scenario of parallel implementation. For one check node update of normalized min-sum algorithm, if the current row weight is dc, dc multiplications are needed. If dc is large, dc multiplications are needed, which leads to high complexity. In this article, one innovative method for check node update has been found, which can obviously reduce the number of multiplication operations for the normalized min-sum algorithm and the number of comparison/selection operations for the row weight matched min-sum algorithm of high rate LDPC codes. Simulations have claimed the performance of normalized min-sum and row weight matched min-sum is nearly the same as that of Log-BP, namely the optimal algorithm, which has shown that normalized min-sum and row weight matched min-sum are good choices for LDPC. View full abstract»

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  • Partial Correlations of Galois Ring Sequences

    Page(s): 157 - 161
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (406 KB) |  | HTML iconHTML  

    Galois ring m-sequences were introduced in the late 1980s and early 1990s, and have near-optimal full periodic correlations. They are related to Z4-linear codes, and are used in CDMA communications. We consider periodic correlation and obtain algebraic expressions of the first two partial period correlation moments of these sequences. These correlation moments have applications in synchronisation performance of CDMA systems using Galois ring m-sequences. View full abstract»

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  • Autocorrelation of Some Quaternary Cyclotomic Sequences of Length 2p

    Page(s): 162 - 166
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    We define a new quaternary cyclotomic sequences of length 2p, where p is an odd prime. We compute the autocorrelation of these sequences. In terms of magnitude, these 4 values. View full abstract»

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  • Expanded LS Code in MC-DC-CDMA system

    Page(s): 167 - 171
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (331 KB) |  | HTML iconHTML  

    This paper presents a novel multicarrier DS-CDMA scheme based on the loosely synchronous (LS) codes, which can achieve very high spectral efficiency and better performance. We present a method to extend LS code on complex plan, with detail description of its construction, and give proof of some properties on such code. At last, simulation results show that the example code has better performance than 8PSK and 8QAM. In practice, this method can be expanded to construct longer LS code, and further improve system performance. View full abstract»

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  • Poly Phase Zero-Correlation Zone Sequences based on Complete Complementary Codes and DFT matrix

    Page(s): 172 - 175
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (291 KB) |  | HTML iconHTML  

    Recently, numerous constructions of zero correlation zone (ZCZ) sequences have been introduced e.g. based on perfect sequences and complete complementary codes etc.. However, the previous construction method which based on complete complementary code is lacking for merit figures when none of whose elements are zero. In this paper, a new construction method of ZCZ sequences based on complete complementary codes is proposed. By proposed method, the poly phase ZCZ sequences with greater than 1/2 merit figure are constructable. View full abstract»

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  • Finite-Length Sequence Pairs With Impulsive Convolution and Their Application to Asymmetric-Key Spread Spectrum Communication System

    Page(s): 176 - 180
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (325 KB) |  | HTML iconHTML  

    In an ad-hoc communication system, the information security between a sender and a receiver must be assured strictly. In this paper, finite-length sequence pairs are introduced for the application to an asymmetric-key spread spectrum communication system. The convolution of the sequence pair gives an impulse except the small values at the first and last ends. The real-valued sequence pairs of length M have the family number of about 2M/radic2piM and are applied to a signature spread spectrum communication system. View full abstract»

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  • Wideband Signal DOA Estimation Based on MP Decomposition

    Page(s): 18 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2232 KB) |  | HTML iconHTML  

    A novel DOA estimation algorithm based on MP decomposition has been proposed. The atom dictionary of the new algorithm is based on the array geometry, and the algorithm is applicable for any phase differentiable signals, both wideband and narrow band signals. Computer simulations demonstrated that the accuracy of this algorithm is better than the algorithm based on WVD. View full abstract»

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  • Properties of Even-Shift Orthogonal Sequences

    Page(s): 181 - 184
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (319 KB) |  | HTML iconHTML  

    This paper investigates properties of the even-shift orthogonal sequence of length 2n, whose out-of-phase aperiodic auto-correlation function takes zero at any even shift. It is shown that the halves of all E-sequences with odd n produced by logic functions are balanced sequences, whose elements 1 and -1 appear half, and there is not any balanced e-sequence for even n. Furthermore it is also shown that the aperiodic auto-correlation function possesses low values at odd shifts. View full abstract»

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  • The Construction of ZCZ Arrays Set Based on Interleaved Technique

    Page(s): 185 - 189
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (315 KB) |  | HTML iconHTML  

    A new construction method of ZCZ arrays set based on interleaved technique is presented. Given perfect periodic autocorrelation array and orthogonal matrix, arrays set with certain zero correlation zone can be constructed through interleaved method. The presented technique has good application foreground in many kinds of array signal design. View full abstract»

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  • Recursion Subspace-Based Method for Bearing Estimation

    Page(s): 190 - 194
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB) |  | HTML iconHTML  

    In this paper, a recursion subspace-based method (RSM) is presented to estimate the bearings of incident signals impinging on a uniform linear array (ULA). Unlike the existing linear operation based methods, such as the signal subspace method without eigendecomposition (SUMWE) of Xin et al, that calculate the noise subspace, the RSM method finds a cleaner signal subspace by means of a successive recursion procedure. Thus, the RSM method has the advantages of computational simplicity and accurate estimation, in particular for a large array. Numerical results are presented to compare the performance the RSM method with that of the SUMWE methods. View full abstract»

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  • A new family of optimal zero correlation zone sequences from Perfect Sequences Based on Interleaved Technique

    Page(s): 195 - 199
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (389 KB) |  | HTML iconHTML  

    In this paper, we present a new method for construction of zero correlation zone (ZCZ) sequence sets, which are optimal with respect to Tang, Fan, and Matsu-fuji bound. The method proposed is based on interleaved technique and a perfect sequence of length m(2k + 1) with m >2, k ges 0. View full abstract»

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  • On Almost Perfect Nonlinear Functions

    Page(s): 2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (921 KB) |  | HTML iconHTML  

    A function F:F[unk]¿F[unk] is almost perfect nonlinear (APN) if, for every a¿0, b in F[unk], the equation F(x)+ F(x+a)=b has at most two solutions [4]. When used as an S-box in a block cipher, it opposes then an optimum resistance to differential cryptanalysis. The function F is almost bent (AB) if the minimum Hamming distance between all its component functions v·F, v ¿ F[unk]{0}, where "·" denotes any inner product in F[unk] and all affine Boolean functions on F[unk] takes the maximal value 2n-1 2(n-1)/2. AB functions exist for n odd only and oppose an optimum resistance to the linear cryptanalysis (see [3]). Every AB function is APN [3], and in the n odd case, any quadratic APN function is AB [2]. The APN and AB properties are preserved by affine equivalence: F~F' if F' = A1[unk] F[unk] A2, where A1, A2 are affine permutations. More generally, they are preserved by CCZ-equivalence [2], that is, affine equivalence of the graphs of F:{(x, F(x)) | x¿F[unk]} and of F'. Until recently, the only known constructions of APN and AB functions were CCZ-equivalent to power functions F(x)=xd over finite fields (F2n being identified with F[unk]). View full abstract»

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  • Zero Correlation Distribution of ZCZ Sequences Obtained from a Perfect Sequence and a Unitary Matrix

    Page(s): 200 - 203
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    A class of zero-correlation zone (ZCZ) sequences constructed by the recursive procedure from a perfect sequence and a unitary matrix was proposed by Torii, Nakamura, and Suehiro (2004). In the reference H. Torii et al. (2004), properties of just enough for the class of sequences used in approximately synchronized CDMA (AS-CDMA) systems were considered. In this paper, we give more detailed distributions of correlation values for their ZCZ sequence sets, and expect that the results make an effect on any applications employing AS-CDMA systems. View full abstract»

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