In the fifth generation era, the pervasive applications of Internet of Things and massive machine-type communications have initiated increasing research interests on the backscatter wireless powered communication (B-WPC) technique due to its ultrahigh energy efficiency and low cost. The ubiquitous B-WPC network is characterized by nodes with dynamic spatial positions and sporadic short packets, of which the performance has not been fully investigated. In this paper, we give a comprehensive analysis of a multiantenna B-WPC network with sporadic short packets under a stochastic geometry framework. By exploiting a time-space Poisson point process model, the behavior of the network is well captured in a decentralized and asynchronous transmission way. We then analyze the energy and information outage performance in the energy harvest and backscatter modulation phases of the backscatter network, respectively. The optimal transmission slot length and division are obtained by maximizing the network-wide spatial throughput. Moreover, we find an interesting result that there exists the optimal tradeoff between the durations of the energy harvest and backscatter modulation phases for spatial throughput maximization. Numerical results are demonstrated to verify our analytical findings and show that this tradeoff region gets shrunk when the outage constraints become more stringent.

In this paper, we consider the problem of joint secure routing and transmit power optimization for a multi-hop ad-hoc network under the existence of randomly distributed eavesdroppers following a Poisson point process. Secrecy messages are delivered from a source to a destination through a multi-hop route connected by multiple legitimate relays in the network. Our goal is to minimize the end-to-end connection outage probability under the constraint of a secrecy outage probability threshold, by optimizing the routing path and the transmit power of each hop jointly. We show that the globally optimal solution could be obtained by a two-step procedure where the optimal transmit power has a closed-form and the optimal routing path can be found by Dijkstra's algorithm. Then a friendly jammer with multiple antennas is applied to enhance the secrecy performance further, and the optimal transmit power of the jammer and each hop of the selected route is investigated. This problem can be solved optimally via an iterative outer polyblock approximation with 1-D search algorithm. Furthermore, suboptimal transmit powers can be derived using the successive convex approximation method with a lower complexity. Simulation results show the performance improvement of the proposed algorithms for both non-jamming and jamming scenarios, and also reveal a non-trivial tradeoff between the numbers of hops and the transmit power of each hop for secure routing.

Mm-wave offers a sensible solution to the capacity crunch faced by 5G wireless communications. This paper comprehensively studies physical layer security in a multi-input single-output mm-wave system, where multiple single-antenna eavesdroppers are randomly located. Concerning the specific propagation characteristics of mm-wave, we investigate two secure transmission schemes, namely maximum ratio transmitting beamforming and artificial noise (AN) beamforming. Specifically, we first derive closed-form expressions of the connection probability for both schemes. We then analyze the secrecy outage probability in both non-colluding eavesdroppers and colluding eavesdroppers scenarios. Also, we maximize the secrecy throughput under a secrecy outage probability constraint, and obtain optimal transmission parameters, especially the power allocation between AN and the information signal for AN beamforming. Numerical results are provided to verify our theoretical analysis. We observe that the density of eavesdroppers, the spatially resolvable paths of the destination and eavesdroppers all contribute to the secrecy performance and the parameter design of mm-wave systems.

In this paper, the performance of non-orthogonal multiple access (NOMA) is investigated and optimized in a downlink space division multiple access network with a multi-antenna base station and randomly deployed users, under a general channel state information (CSI) limited feedback framework. We first propose a dynamic user scheduling and grouping strategy by leveraging limited feedback. Based on that, an analytical framework is proposed to obtain the outage probability of the network in closed form. The diversity order and the impacts of the number of feedback bits on the outage performance of NOMA are analyzed. Furthermore, the net throughput, which captures the network-wide throughput with the uplink feedback cost considered, is maximized by optimizing the number of feedback bits. Numerical results are demonstrated to verify our analytical findings and show that different from the perfect CSI case, there always exists a performance floor of outage probability in the considered network due to limited feedback. Moreover, the optimal number of feedback bits for net throughput maximization increases as the channel coherence time becomes longer.

Cognitive radio is emerging as one of the key information transmission technologies to enhance spectrum efficiency for dramatically increased wireless network capacity requested by end users. Dynamic spectrum access allows effective use of radio frequency and prevents its underutilization in many real-world networks. It enables unlicensed users to temporarily “borrow” unused spectrum while ensuring that the rights of the incumbent license holders are respected. Problems of optimization of joint access of primary and secondary users can be effectively solved by means of queueing theory. In this paper, the analysis of a novel queueing model suitable for the optimization of access is implemented under quite general assumptions about the system parameters. There are several types of primary customers having different requirements for the service time and preemptive priority over secondary customers. Secondary customers can share a server, while primary customers occupy the whole server. The arrival flow is described by the marked Markovian arrival process. The service time distribution is of phase-type. Effect of retrials of secondary customers is taken into account. An effective way for the analysis of multi-server queues with many types of customers and heterogeneous requirements to the service process is provided and applied.

With the recent emergence of 5G era, heterogeneous cellular networks (HCNs) have invoked a popular research interest. In this paper, we provide a comprehensive analysis for multi-antenna transmissions in a multi-tier downlink HCN. We first propose a reliability-oriented threshold-based mobile association policy, where each user connects to the strongest base station from which this user can obtain the largest truncated long-term received power. Under our mobile association policy, we derive analytical expressions for the exact outage probability of an arbitrary randomly located user, along with computationally convenient lower and upper bounds. Asymptotic analysis on the outage probability shows that introducing a large access threshold into mobile association significantly decreases the outage probability. We further investigate the spectrum efficiency and the energy efficiency of the HCN. Our theoretic analysis and numerical validations show that both the spectrum and energy efficiencies can be improved by properly choosing the access threshold.

This paper studies physical layer security in a wireless ad hoc network with numerous legitimate transmitter-receiver pairs and eavesdroppers. A hybrid full-duplex (FD)/half-duplex receiver deployment strategy is proposed to secure legitimate transmissions, by letting a fraction of legitimate receivers work in the FD mode sending jamming signals to confuse eavesdroppers upon their information receptions, and letting the other receivers work in the half-duplex mode just receiving their desired signals. The objective of this paper is to choose properly the fraction of FD receivers for achieving the optimal network security performance. Both accurate expressions and tractable approximations for the connection outage probability and the secrecy outage probability of an arbitrary legitimate link are derived, based on which the area secure link number, network-wide secrecy throughput, and network-wide secrecy energy efficiency are optimized, respectively. Various insights into the optimal fraction are further developed, and its closed-form expressions are also derived under perfect self-interference cancellation or in a dense network. It is concluded that the fraction of FD receivers triggers a non-trivial tradeoff between reliability and secrecy, and the proposed strategy can significantly enhance the network security performance.

In this paper, we study the benefits of full-duplex (FD) receiver jamming in enhancing the physical-layer security of a two-tier decentralized wireless network with each tier deployed with a large number of pairs of a single-antenna transmitter and a multi-antenna receiver. In the underlying tier, the transmitter sends unclassified information and the receiver works in the half-duplex (HD) mode receiving the desired signal. In the overlaid tier, the transmitter delivers confidential information in the presence of randomly located eavesdroppers, and the receiver works in the FD mode radiating jamming signals to confuse eavesdroppers and receiving the desired signal simultaneously. We provide a comprehensive performance analysis and network design under a stochastic geometry framework. Specifically, we consider the scenarios where each FD receiver uses single- and multi-antenna jamming, and analyze the connection probability and the secrecy outage probability of a typical FD receiver by deriving accurate expressions and more tractable approximations for the two probabilities. We also determine the optimal deployment density of the FD-mode tier to maximize the network-wide secrecy throughput subject to constraints including the given dual probabilities and the network-wide throughput of the HD-mode tier. Numerical results are demonstrated to verify our theoretical findings, and show that the network-wide secrecy throughput is significantly improved by properly deploying the FD-mode tier.

We consider collusion-resistant fingerprinting codes for multimedia content. We show that the corresponding IPP-codes may trace all guilty users and at the same time have exponentially many code words. We also establish an equivalence between signature codes for the A-channel and multimedia fingerprinting codes and prove that the rate of the best t-signature codes for A-channel is at least Θ(t-2). Finally, we construct a family of t-signature codes for the A-channel with polynomial decoding complexity and rate Θ(t-3).

The heterogeneous cellular network (HCN) is a promising approach to the deployment of 5G cellular networks. This paper comprehensively studies physical layer security in a multitier HCN where base stations (BSs), authorized users, and eavesdroppers are all randomly located. We first propose an access threshold-based secrecy mobile association policy that associates each user with the BS providing the maximum truncated average received signal power beyond a threshold. Under the proposed policy, we investigate the connection probability and secrecy probability of a randomly located user and provide tractable expressions for the two metrics. Asymptotic analysis reveals that setting a larger access threshold increases the connection probability while decreases the secrecy probability. We further evaluate the network-wide secrecy throughput and the minimum secrecy throughput per user with both connection and secrecy probability constraints. We show that introducing a properly chosen access threshold significantly enhances the secrecy throughput performance of a HCN.

Multiple antennas can provide huge capacity gains when the transmitter knows the channel state information (CSI). In multiple-input multiple- output (MIMO) wireless system, CSI at transmitter (CSIT) side can significantly improve system performance by increasing the transmission rate and enhancing reliability. Precoding is a technique that exploits CSIT by processing the signal before transmitting. In this paper, a new precoding scheme called hybrid multiple-input multiple-output precoding (HMP) is proposed. HMP is the combination of a linear and a nonlinear precoder. In HMP, nonlinear precoding in the good channel and linear precoding in the bad channel is used. The well-known Tomlinson-Harashima precoding (THP) is considered as nonlinear precoding. If number of transmit antennas is chosen less than or equal to four, HMP has no use, conventional antenna selection scheme would better perform. Therefore, for perform better at least four or more Tx antennas need to be chosen. The system achievable rate is calculated to show the performance of HMP scheme compared with the conventional scheme.

In this paper, we provide a comprehensive study of secrecy transmission in decode-and-forward (DF) relay networks subjected to slow fading. With only channel distribution information (CDI) of the wiretap channels, we aim at maximizing secrecy throughput of the two-hop transmission under a secrecy outage constraint through optimizing transmission region, rate parameters of the wiretap codes and power allocation between the source and relay. We propose fixed transmission parameter scheme (FTPS) and variable transmission parameter scheme (VTPS), which are based on the CDI and instantaneous channel state information of the main channels, respectively. In both schemes, source and relay use the same codeword, and the eavesdropper can use maximum ratio combining (MRC) reception. To improve the secrecy throughput, we further propose VTPS-D1 and VTPS-D2 schemes, where the source and relay either use independent codewords with identical code rates, or different codebooks with different code rates so that the eavesdropper can only decode the two-hop signals individually rather than using MRC. We provide explicit results on the design for all proposed schemes. Numerical results and comparisons on the secrecy throughput of these schemes are presented to reveal their respective superiorities and give some insights into the choice of design scheme.

In this paper, we study the secure multi-antenna transmission with artificial noise (AN) under slow fading channels coexisting with randomly located eavesdroppers. We provide a comprehensive secrecy performance analysis and system design/optimization under a stochastic geometry framework. Specifically, we first evaluate the secrecy outage performance, and derive a closed-form expression for the optimal power allocation ratio of the information signal power to the total transmit power that minimizes the secrecy outage probability (SOP). Subject to a SOP constraint, we then propose a dynamic parameter transmission scheme (DPTS) and a static parameter transmission scheme (SPTS) to maximize secrecy throughput, and provide explicit solutions on the optimal transmission parameters, including the wiretap code rates, the on-off transmission threshold and the power allocation ratio. Our results give new insight into secure transmission designs. For example, secrecy rate is a concave function of the power allocation ratio in DPTS, and AN plays a significant role under SOP constraints and in dense eavesdropper scenarios. In SPTS, transmission probability is a concave function of the power allocation ratio, and secrecy throughput is a quasi-concave function of the secrecy rate. Numerical results are demonstrated to validate our theoretical analysis.

Using a method for constructing self-dual codes having an automorphism of odd prime order, we classify up to equivalence all binary self-dual codes with an automorphism of order 11 with 6 cycles and minimum distance 12. This classification gives new [72, 36, 12] codes with weight enumerator that was previously not obtained as well as many [66, 33, 12], [68, 34, 12], and [70, 35, 12] codes with new values of the parameters in their respective weight enumerators.

Progressive edge-growth (PEG) algorithm construction builds a Tanner graph, or equivalently a parity-check matrix, for an LDPC code by establishing edges between the symbol nodes and the check nodes in an edge-by-edge manner and maximizing the girth in a greedy fashion. This approach is simple but the complexity of the PEG algorithm scale is O(nm), where n is the number of symbol nodes and m is the number of check nodes. We deal with this problem by construct a base matrix Hbof size mb× nbwith the PEG algorithm and simultaneously expand this base matrix into a parity-check matrix H of size mx n via the the Chinese remainder theorem (CRT), where m ≫ mband n ≥ nb. The size of the base matrix is expanded without decreasing the girth. For convenience, the PEG and CRT combined algorithm is referred to as the PEG-CRT algorithm in this paper. Since a smaller matrix is constructed with the PEG algorithm and the complexity of the CRT computation is negligible compared to the PEG algorithm, the complexity of the whole code construction process is reduced. Furthermore, the proposed algorithm has a potential advantage of saving storage space by storing a smaller matrix Hband expanding it to H "on-the-fly" in hardware. The expanded matrix H preserves the important properties of base matrix such as large girth, flexible code rate and low density. The complexity analysis shows that the complexity of the PEG-CRT algorithm does not grow with the code length n. Simulation results show that compared with the PEG LDPC codes of length nb, the expanded PEG-CRT LDPC codes have better bit error rate (BER) performance with the iterative decoding. It is also shown that compared with PEG LDPC codes of length n, which constructed with higher complexities, the PEG-CRT codes have similar BER performance.

In this paper, maximal-ratio combining (MRC) and selection combining (SC) are proposed in spectrum sharing single-carrier networks with multiple primary user receivers (PU-Rxs). Taking into account the peak interference power at the PU-Rx's and the maximum transmit power at the secondary user (SU), the impact of multiple PU-Rx's on the secondary network is characterized when the secondary user receiver (SU-Rx) is equipped with multiple antennas. In doing so, exact and asymptotic expressions are derived for the cumulative distribution function, taking into account two realistic scenarios: non-identical frequency selective fading between the secondary user transmitter (SU-Tx) and the PUs, and frequency selective fading between the SU-Tx and the SU-Rx. Based on these, exact and asymptotic expressions for the outage probability and average bit error rate are derived. Furthermore, an exact closed-form expression for the ergodic capacity is derived. It is shown that the asymptotic diversity gain depends only on the number of receive antennas and the number of multipath channels. It is further shown that the number of PU-Rx's and fading severities between the SU-Tx and the PU-Rx's have no impact on the asymptotic diversity gain.

Coordinated Multi-Point (CoMP) transmission is a technology targeted for Long Term Evolution Advanced (LTE-A). The Joint Processing (JP) technique for CoMP can maximize system performance, which is achieved mainly with channel information-based beamforming algorithms. Precoding methods perform differently in various CoMP scenarios. In this paper, we propose a joint processing scheme in downlink CoMP transmission system. We apply block diagonal beamforming to downlink transmission, and assume perfect knowledge of downlink channels and transmit messages at each transmit point.

In this paper, we propose a new method to transmit one more information bit by using orthogonal Space-Time Block Codes (STBC) for 4 antennas. Using two different STBCs matrices transmit one additional bit to achieve high rate-9/8. To maintain full rank and full diversity for the coding gain matrix, a new STBC code with full rate and full diversity is proposed in this letter. In order to implement a fast Maximum-likelihood (ML) decoding, a property of Frobenius norms of received signals is considered to reduce its complexity by checking the non-null values of the Frobenius at the transmitter side. Simulation results show that this method achieves better bit error rate (BER) performance and throughputs in the high SNR region without losing diversity gain.

A quantum TITO (Two-Input-Two-Output) diversity transmission scheme for the entangled-state message is proposed by generalizing the wireless transmission technique to the quantum field. The TITO quantum teleportation can be implemented with non-maximally entangled Bell states in order to enhance the security and fidelity of the quantum channel, in which a quantum signal sequence with n entangled quantum states can be transmitted through the TITO quantum channel by applying the diversity technology. The analysis shows that the quantum TITO transmission can be achieved securely and with an expected fidelity.

Progressive edge-growth (PEG) algorithm construction builds the Tanner graph for an LDPC code by establishing edges between the symbol nodes and the check nodes in an edge-by-edge manner and maximizing the local girth in a greedy fashion. This approach is simple but the computational complexity of the PEG algorithm scale as O(nm), where n is the number of symbol nodes and m is the number of check nodes. We deal with this problem by first construct a base LDPC code of length n1with the PEG algorithm and then extend this LDPC code into an LDPC code of length n, where n ≥ n1, via the the chinese remainder theorem (CRT). This method increase the code length of an LDPC code generated with the PEG algorithm, without decreasing its girth. Due to the code length reducing in the PEG construction step, the computational complexity of the whole code construction process is reduced. Furthermore, the proposed algorithm have a potential advantage by storing a small parity-check matrix of a base code and extending it “on-the-fly” in hardware.

In this paper, we present a channel estimation using radio frequency (RF) signal processor for orthogonal frequency division multiplexing (OFDM) system. We have evaluated the channel impulse response on OFDM symbols and easily estimated the multiple-input-multiple-output-orthogonal frequency division multiplexing (MIMO-OFDM) channel using an RF baseband signal processor and minimum mean square error (MMSE) detector. This paper inquire about the single input single output orthogonal frequency division multiplexing (SISO-OFDM) and extend to a MIMO-OFDM system to improve the bit-error-rate (BER) performance without enhancing the number of RF front-end elements in the receiver.

The interpolation step of the Wu list decoding algorithm for Reed–Solomon codes is considered. The problem is reformulated as construction of a partially homogenized interpolation polynomial. A generalization of the binary interpolation algorithm, which is based on the novel formulation of the interpolation step, is provided. It enables complexity reduction both with respect to the Wu method based on the iterative interpolation algorithm, as well as the Guruswami–Sudan method based on re-encoding and the binary interpolation algorithm.

A concatenated code construction based on folded Reed-Solomon codes and short inner linear block codes is proposed. A generalization of the Das-Vardy weight assignment scheme to the case of multivariate interpolation decoding is developed. The decoding algorithm for the proposed construction makes use of the weighted version of the Guruswami-Rudra list decoding algorithm and list decoding of inner codes.

The Hadamard transform is an orthogonal transform with highly practical values for signal sequence transforms and data processing. Jacket matrices, which are motivated by the center weight Hadamard matrices, are a class of matrices with their inverse being determined by the element-wise of the matrix. Mathematically, let A = (akt) be a matrix, if A-1= (akt-1)T, then the matrix A is a Jacket matrix, where (·) denotes a matrix and T denotes the transpose. Since inverse of the Jacket matrix can be calculated easily, it is very helpful to employ this kind of matrix in the signal processing, encoding, mobile communication, image compression, cryptography, etc. Especially, the interesting orthogonal matrices, such as Hadamard, Haar, DFT, slant matrices, belong to the Jacket matrix family. In addition, Jacket matrices are associated with many kinds of matrices, such as unitary matrices and Hermitian matrices which are very important in signal processing, communication (e.g., encoding), mathematics, and physics.

A novel quantum anonymous communication scheme is proposed on the basis of Dining Cryptographers (DC) Problem and nonmaximally entangled qubit pair. The scheme takes advantage of quantum-mechanical impossibility of local unitary transformation between certain nonmaximally entangled states to provide truly random number which can be brightly used in anonymous communication protocols based on DC-Nets. The analysis and discussions demonstrate that the proposed quantum anonymous communication scheme can be performed securely with high capacity and untraceability. The scheme can also be extended to a (2, 2) quantum secret sharing (QSS) scheme.

A novel (n, n) scheme of multiparty quantum group signature of classical or quantum message is proposed based on the discrete quantum Fourier transform. The generation and verification of the signature can be processed only if all the n participants work in concert. Moreover, a new verification manner, in which the message owner and the signing group separately verify the signature on both side by using the entangled state of EPR sequence, is involved in this paper. Security analysis shows that it is feasible to achieve a secure quantum group signature with the secure quantum computation.

This paper presents methods to the construction of regular and irregular low-density parity-check (LDPC) codes based on Euclidean geometries. Codes constructed by these methods are quasi-cyclic. The degree distributions of proposed LDPC codes can be optimized by the curve fitting approach in the extrinsic information transfer (EXIT) charts. Simulation results show that these codes perform very well with the iterative decoding.

In this paper, the issue of capacity enhancement and power allocation has been presented using multi-antenna relay system. The multi-antenna relay system is constructed by a selective decode-and-forward (SDF) and an incremental-decode-and-forward (IDF) protocol. These two protocols are jointly introduced in a cooperative relay network. We have derived the issues of outage capacity and power allocation for each protocol and demonstrated that they can outperform high capacity and allocated 90% power. All relay input signals are combined, re-encoded and re-transmitted to the destination. We have proposed the multi-antenna relay with the joint protocol relay system which efficiently enhances the capacity and power allocation of the cooperative networks.

This paper introduces a class of Semi-Random (SR) Low-Density Parity-Check (LDPC) codes and a class of Quasi-Cyclic (QC) LDPC codes. Both of them are derived from Multiple Serially Concatenated Multiple Parity-Check (M-SC-MPC) codes and interleavers, therefore, have low encoding complexities. These two codes are called M-SR-LDPC codes and M-QC-LDPC codes, respectively, in this paper. The M-SR-LDPC codes are designed with the modified Progressive Edge-Growth (PEG) algorithm and the M-QC-LDPC codes are designed with the existing cycle-condition formula. Consequently, the proposed codes have large girths. Simulation results show that our codes perform very well over the AWGN channel with iterative decoding.

Progressive edge-growth (PEG) algorithm is known to construct low-density parity-check (LDPC) codes at finite code lengths with large girths. A simple variation of the PEG algorithm, linear-encoding PEG (LPEG) algorithm, can be applied to generate linear encodable LDPC codes. This paper presents a modified LPEG algorithm to construct fast encodable LDPC codes with a certain girth constraint. The presented fast encodable LDPC codes facilitate the parallel encoding processes for parity bit generations. Therefore, their encoding time is much shorter than that of LPEG codes.

In, the authors have proposed an analysis on the problem of space-time coding for a synchronized wireless relay networks employing AF (Amplify-and-Forward) protocol which proposes LD (linear dispersion coding) by using linear transformation. In this paper, we extend it to a asynchronous wireless networks and to reduce more processing burden on the relay nodes by allocating interleavers at each relay node. Based on distributed interleavers, we present a new method to encode distributed space-time code at relay nodes achieving full spatial diversity for an asynchronous wireless relay network. We also propose an efficient decoding algorithm, which orders the joint channel coefficients of overall channel consisting source-relay link and relay-destination link and cancels the previous decoded symbols at the next decoding procedure.

It is well-known that the performance of the relay-based decode-and-forward (DF) cooperative networks outperforms the performance of the amplify-and-forward cooperative networks. However, this performance improvement is accomplished at the expense of adding more signal processing complexity (precoding/decoding) at each relay node. In this study, the authors tackle this signal processing complexity issue by proposing a Jacket-based fast method for reducing the precoding/decoding complexity in terms of time computation. Jacket transforms have shown to find applications in signal processing and coding theory. Jacket transforms are defined to be n×n matrices A=(ajk) over a field ℱ with the property AA†=nIn, where A† is the transpose matrix of the element-wise inverse of A, that is, A†=(akj−1), which generalise Hadamard transforms and centre weighted Hadamard transforms. In particular, exploiting the Jacket transform properties, the authors propose a new eigenvalue decomposition (EVD) method with application in precoding and decoding of distributive multi-input multi-output channels in relay-based DF cooperative wireless networks in which the transmission is based on using single-symbol decodable space-time block codes. The authors show that the proposed Jacket-based method of EVD has significant reduction in its computational time as compared to the conventional-based EVD method. Performance in terms of computational time reduction is evaluated quantitatively through mathematical analysis and numerical results.

In this paper, we propose a simple orthogonal space time transmission scheme for asynchronous cooperative systems. In the proposed scheme, OFDM is implemented at the source node, some very simple operations, namely time reversion and complex conjugation, are implemented at the relay nodes, and a two-step of cyclic prefix (CP) removal is performed at the destination. The CP at the source node is used for combating the frequency selective fading channels and the timing errors. In this scheme, the received signals at the destination node have the orthogonal code structure on each subcarrier and thus it has the fast symbol-wise ML decoding and can achieve full spatial diversity when SNR is large without the requirement of symbol level synchronization. It should be emphasized that since no Add/Remove CP or IFFT/FFT operation is needed at the relay nodes, the relay nodes do not have to know any information about the channels and the timing errors, and the complexity of the relay nodes is very low.

This paper presents a new design and implementation of a 32-bit decimal floating-point (DFP) logarithmic converter based on the digit-recurrence algorithm. The converter can calculate accurate logarithms of 32-bit DFP numbers which are defined in the IEEE 754-2008 standard. Redundant digit e1is obtained by look-up table in the first iteration and the rest redundant digits ejare selected by rounding the scaled remainder during the succeeding iterations. The sequential architecture of the proposed 32-bit DFP logarithmic converter is implemented on Xilinx Virtex-II Pro P30 FPGA device and then synthesized with TMSC 0.18-um standard cell library. The implementation results indicate that the maximum frequency of the proposed architecture is 47.7 MHz in FPGA and 107.9 MHz in TMSC 0.18-um technology. The faithful 32-bit DFP logarithm results can be obtained in 18 cycles.

In, the authors have presented a detailed analysis on the problem of distributed space-time coding employing Amplify-and-Forward (AF) protocol for a synchronized wireless relay networks, where maximum likelihood (ML) decoding is employed. In this paper, an iterative turbo-like decoder is introduced to improve system performance by allocating interleavers at each relay node and using multiuser concept. Due to different overall channel gains consisting source-relay link and relay-destination link, ordering and canceling techniques of interferences are considered in our design. Simulation results show an accepted improvement in the high SNR region.

We present a new real orthogonal design on some Hadamard/DFT/DCT polynomials. As examples, some proposed real orthogonal codes are constructed from the Hadamard 2-by-2 polynomial. The motivation of the proposal is based on Euler theorem, which gives the circle limitation and algebra for computing the elements. According to the proposed real codes, the inverse of the resultant matrices can be easily obtained from the element inverse by modulo operation as Jacket matrices.

This paper presents a new design and implementation of a 32-bit decimal floating-point (DFP) antilogarithmic converter based on the digit-recurrence algorithm with selection by rounding. The converter can calculate the accurate antilogarithm (10dec) of the 32-bit DFP numbers which are defined in the IEEE 754-2008 standard. The sequential architecture of the proposed 32-bit DFP antilogarithmic converter is implemented on Xilinx Virtex-II Pro P30 FPGA device. The proposed architecture occupies 2, 315 out of 13696(16%) slices and can obtain a faithful 32-bit DFP antilogarithm in 11 clock cycles running at 51.5 MHz. The 7-digit decimal fixed-point (FXP) antilogarithmic converter is an essential operational part of the 32-bit DFP antilogarithmic converter. We transform it to a 7-digit decimal exponential converter to compare with a 24-bit binary FXP exponential converter. The compared results show that the 7-digit decimal exponential converter occupies 2.18 times more area and 1.66 times slower than the 24-bit binary FXP exponential converter.

This paper presents an efficient hardware implementation of a hybrid architecture to compute three 8-point transforms - the Discrete Cosine Transform, the Discrete Fourier Transform, and the Discrete Wavelet Transform on a single FPGA. The architecture is based on an element-wise matrix factorization and row-permutation algorithm, where the forward basis transformation matrices are decomposed into multiple sub-matrices and the common units are shared among them. The hardware implementation is parallel, pipelined and multiplication-free; it costs only 2,073 logic cells, 1,476 registers and runs at maximum frequency of 118 MHz with a very high process throughput of 944 Megabits/sec when synthesized onto an Altera FPGA device. The synthesized results for other FPGA technologies are also presented for performance assessment.

In 2001 Lee, Rajan and Park introduced (among other things) the concept of extended complex reverse jacket (CRJ) transform over finite field. In this paper, we prove that this transform is equivalent to Galois field Fourier (GFF) transform and possesses an additional feature of having a matrix with specific border. We also, present examples of Jacket transforms over finite fields applicable to odd dimensions extending in this way previous works on the subject.

This letter presents an approach to the construction of non-binary low-density parity-check (LDPC) codes based on alpha-multiplied circulant permutation matrices and hyperplanes of two different dimensions in Euclidean geometries. Codes constructed by this method have large girth and high binary column weight when the order of Galois field is high. Simulation results show that these codes perform very well with fast Fourier transform (FFT) based sum-product algorithm (SPA).

During the last few years, a number of Quasi-Orthogonal Space-Time Block Codes (QOSTBC) have been proposed for using in multiple transmit antennas systems. In this letter, based on circulant matrix, we propose a novel method of extending any QOSTBC constructed for 4 transmit antennas to a closed-loop scheme. We show that with the aid of multiplying the entries of QOSTBC code words by the appropriate phase factors which depend on the channel information, the proposed scheme can improve its transmit diversity with one bit feedback. The performances of the proposed scenario extended from Jafarkhani's QOSTBC as well as its optimal constellation rotated scheme are analyzed. The simulation results suggest that there is a significant Eb/No advantage in the proposed scheme which is able to be designed easily.

In this paper, we present a new class of cocyclic Jacket matrices over complex number field with any size. The known cocyclic Jacket matrices belong to this class of matrices. With the aid of the Kronecker product of the lower order cocyclic Jacket matrix and the identity matrix, the fast algorithms for realizing the cocyclic Jacket transform are proposed.

Hadamard transform has played a great part in Jacket transform. Motivated by Jacket transform, we propose a simple approach for space time block codes (STBC) design by using the Hadamrd in this letter,which achieves full rate, full diversity and employs simple decoding. The orthogonal STBC may be designed easily by using the proposed approach. Especially the performance of the designed orthogonal STBC may be improved greatly.

Jacket matrices motivated by the center weight Hadamard matrices have play some important roles in signal processing and communication. In this paper we proposed a notation called block jacket matrices which substitute elements of matrices into matrices or even block matrices. Employing the well-known Pauli matrices which are very important in many subjects, several kind of block jacket matrices are constructed. Especially, construction and properties of the block jacket matrices with size 2nand 3nare investigated. Then a general approach for any size block jacket matrices is proposed. With novel properties of the block jacket matrices, a fast block inverse jacket transform is suggested.

Particle swarm optimization algorithm (PSO) has showed great advantage in solving multidimensional and non-linear problems, and it is easy to be applied. By improving binary particle swarm optimization (BPSO) algorithm and applying it in direct sequence code-division multiple-access (DS-CDMA) system as a multiuser detection algorithm, a BPSO multiuser detection (BPSO-MUD) is proposed in this paper and the relationship between the physical meaning of each variable in BPSO-MUD and DS-CDMA system is described clearly, followed by the discussion of highly efficient multiuser detection (MUD). Simulations show that these proposed detections are benefited greatly from the BPSO, they have significant performance improvements over conventional detection (CD), and they approach the performances without multiple access interference (MAI) in CDMA system; moreover they are easy to be applied in CDMA system.

Jacket transforms are a class of transforms that are simple to calculate, easily inverted, and size-flexible. Previously reported jacket transforms were generalizations of the well-known Walsh-Hadamard transform (WHT) and the center-weighted Hadamard transform (CWHT). In this letter, we present a new class of jacket transform not derived from either the WHT or the CWHT. This class of transform can be applied to any even length vector, is applicable to finite fields, and is useful for constructing error control codes

The average conditional entropy of the key given the message and its corresponding cryptogram, ff(K|M, C), which is refer as a key appearance equivocation, was proposed as a theoretical measure of the strength of the cipher system under a known plaintext attack by Dunham in 1980. In the same work (among other things), lower and upper bounds for H(SM |MLCL) are found and its asymptotic behavior as a function of cryptogram length L is described for simple substitution ciphers, i.e., when the key space SLambda1, Is the symmetric group acting on a discrete alphabet M. In the present paper we consider the same problem when the key space is an arbitrary subgroup KMand generalize Dunham's result.

We address a new representation of DCT/DFT matrices via one hybrid architecture. Based on a element inverse matrix factorization algorithm, we show that the DCT and DFT have a same recursive computational pattern, and we can develop an hybrid architecture by using some diagonal matrices.

Traitor tracing is one kind of piracy deterrent schemes that helps trace the source of leaks when sensitive or proprietary data is made available to a large set of parties. In such schemes, error correcting codes can be applied for their natural properties, known as traceability codes. In this paper, we present Reed-Solomon codes as a kind of traceability codes and use list decoding algorithm to efficiently trace the traitors. We place our emphasis upon the conditions under which list decoding algorithm can be applied successfully for Reed-Solomon codes and the maximum numbers of users and traceable traitors for particular codes.

This paper proposes a FIR-RAKE receiver algorithm that makes use of a pilot signal broadcast by the TD-SCDMA (time division-synchronous code division multiple access) base station to obtain channel parameter estimates in the downlink of TD-SCDMA wireless network. The algorithm can reduce multipath interference for the mobile units and with lower complexity of FIR implementation, where only one marching filter has been adopted. Performance analysis presented in the paper and computer simulations confirm that the proposed FIR-RAKE receiver algorithm achieves a better performance under typical multipath fading propagation conditions.

One-dimensional and two-dimensional fast algorithms for realizing the block inverse jacket transform with size of N=2/sup k/ and 3/sup k/ are proposed. The fast algorithms are based on sparse matrix factorization of the block inverse jacket matrix and recursive form of the Kronecker products of identity matrices and successively lower-order block inverse jacket matrices.

The multilevel code (MLC) has attracted considerable attention as a means to achieve bandwidth and power efficiency. Additionally, the LDPC codes by the u/u+v construction have flexible rate or length. By combing with them, we investigate an efficient way for variable rates data transmission in this paper. The study can enrich the family of LDPC codes and their applications.

Jacket transforms are a class of transforms which are simple to calculate, easily inverted and are size-flexible. Previously reported jacket transforms were generalizations of the well-known Walsh-Hadamard transform (WHT) and the center-weighted Hadamard transform (CWHT). In this paper we present a new class of jacket transform not derived from either the WHT or the CWHT. This class of transform can be applied to any even length vector, and is applicable to finite fields and is useful for constructing error control codes.

In this paper, a new family of hopping sequences with very large family size suitable for use in time/frequency-hopping (TH/FH) code-division multiple-access (CDMA) systems is proposed and investigated. The construction of the new hopping sequences is based upon the polynomial theory over the finite field, and the new hopping sequences are called the polynomial hopping sequences. It is shown that the new time/frequency-hopping sequences include the well-known cubic hopping sequences, quadratic hopping sequences, and linear hopping sequences as special cases, and are good candidates for the large-capacity ultrawide-bandwidth (UWB) radio systems.

The sensitivities of the bits of low weight codewords in turbo codes to noises are discussed firstly and the result is that the lower weight the higher sensitivity. Theoretical analysis shows that through the protections on such key-bits which have high sensitivities; the minimal weight of the codes can be improved apparently. The simulations also give out the supported results: The BER could be highly improved at high Eb/N0 for code rates both 1/3 and 1/2.

In this paper, the construction of semi-algebra Low-density parity-check (LDPC) code with an arbitrary block length is presented. The encoding circuit is based on the original semi-algebra design and users can have the choice of using the matrix pattern and various code rates to design for different communication applications. Especially, a novel girth scheme named Adaptive Slope Group (ASG) is proposed for the semi-algebra code design with the large girth and maximum minimum distance. We can compare the performance of this novel semi-algebra LDPC code against the Shannon limit for several rates. The simulation results show our codes can perform a large coding gain at high SNRs with BPSK modulation over AWGN channels. However, column weight j is not random, only for j=2.

Space-time block codes (STBC) from orthogonal designs (OD), quasi-orthogonal designs (QOD) and co-ordinate interleaved orthogonal designs (CIOD) have been attracting wider attention due to their amenability for fast (single-symbol decoding for OD, CIOD and double-symbol decoding for QOD) ML decoding, and rate-one with full-rank over quasi-static fading channels. The importance of CIOD is due to the fact that, rate-one, full-rank, square ODs for arbitrary complex constellations exist only for 2 transmit antennas while such a CIOD exists for 2,3 and 4 transmit antennas with a slight restriction on the complex constellations (Zafar Ali Khan and B. Sundar Rajan, Proc. IEEE ISIT 2002, p.275, 2002; DRDO-IISc Tech. Report No. TR-PME-2002-17, 2002). These limitations motivate study of rectangular (non-square) designs. One way of obtaining rectangular designs is by deleting columns from square or non-square ODs or CIODs. We present a new construction of rectangular single-symbol decodable designs that have higher maximum mutual information than those obtained by deleting columns of CIODs and has lower peak-to-average-power ratio (PAPR). Simulation results are presented for three and five transmit antennas and compared with that of OD, QOD, CIOD to demonstrate the superiority of the proposed rectangular designs.

In this paper, we design a novel multilevel coding (MLC) for multiple antennas transmission system, in which space diversity is achieved by using space-time block codes (STBC). In terms of system performance and implementation, semi-algebraic low-density parity-check (SA-LDPC) codes are proposed as component codes for MLC. The iterative multistage decoding (IMSD) scheme is adopted in system. System performance with ungerboeck partitioning (UP) and block partitioning (BP) for 8PSK is evaluated respectively over flat Rayleigh fading channels. Comparing with STBC, through many simulations, the significant performance improvement is obtained by concatenating the MLC with STBC in wireless channels. Furthermore, it is shown that the proposed transmission scheme outperforms space-time trellis codes (STTC) and concatenated STBC with trellis coded modulation (TCM) under the same signal constellation.

Abstract This paper proposes a class of space time parallel (STP) iterative coding scheme to combat fading for wireless MIMO systems. In addition to the inner iterations, thesuper iterations(or outer iterations) and symbol interleaved space time coding are employed to achieve additional time diversity and coding gain in fading channel. The numerical and simulation results demonstrate that the STP iterative coding scheme may make use of all the advantages of transmit diversity and time diversity in wireless MIMO systems. In particular, in the case of STP turbo codes, about 1 dB BER enhancement and half calculation time reduction from conventional space time (ST) turbo codes designs are achieved; in the case of low density parity check (LDPC) codes, about 0.8 dB improvement from conventional ST LDPC designs is obtained. Copyright © 2003 John Wiley & Sons, Ltd.

A code is s-quasi-cyclic (s-QC) if there is an integer s such that cyclic shift of a codeword by s-positions is also a codeword. For s = 1, cyclic codes are obtained. A dyadic code is a code which is closed under all dyadic shifts. An s-QC dyadic (s-QCD) code is one which is both s-QC and dyadic. QCD codes with s = 1 give codes that are cyclic and dyadic (CD). We obtain a simple characterization of all QCD codes (hence of CD codes) over any field of odd characteristic using Walsh-Hadamard transform defined over that finite field. Also, it is shown that dual a code of an s-QCD code is also an s-QCD code and s-QCD codes for a given dimension are enumerated for all possible values of s.

The class of reverse jacket matrices (~RJ\/sub N/) is defined; the main property of ~RJ\/sub N/ is that the inverse matrices of its elements can be obtained very easily and have a recursive structure. ~RJ\/sub N/ is a generalized form of the weighted Hadamard transform. Each element of ~RJ\/sub N/ can be used to the subsampling matrix. These matrices can be further used to develop efficient algorithms in PCS signal processing as well as in coding and information theory.