Full-rate Codes Research Articles

Optimal Construction of Regenerating Code Through Rate-Matching in Hostile Networks

Regenerating code is a class of distributed storage codes that can optimally trade the bandwidth required to repair a failed node with the amount of data stored per node. There are two optimal points in the regeneration tradeoff curve: the minimum storage regeneration code and the minimum bandwidth regeneration code. However, in hostile networks where the storage nodes may be compromised, the storage capacity of the network can be significantly affected. In this paper, we propose two optimal regenerating code constructions through rate-matching to combat this kind of adversarial attacks in hostile networks. We first develop a two-layer rate-matched regenerating code construction. By matching the parameters of the full rate code and the partial rate code, we can optimize the overall storage efficiency while maintaining the corrupted node detection probability. Through comprehensive analysis, we show that the two-layer rate-matched regenerating code can achieve 70% higher storage efficiency than the universally resilient regenerating code. We then propose an optimal $m$ -layer regenerating code construction. While the principle remains the same as the two-layer code, it is designed to optimize the total number of detectable corrupted nodes of $m$ layers from which the errors can be corrected under the constraint of any given code efficiency. Compared with the universally resilient regenerating code with the same rate, our $m$ -layer code can detect 50% more corrupted nodes.

Full code rate complex orthogonal STBCS for multiple transmit antennas

Alamouti is Pioneer of Complex Orthogonal STBCS for two transmit branch diversity with code rate one. Then Tarkoh found for three and four transmit antennas with code rate 3/4 . Jafarkhni proposed for non orthogonal STBCS four transmit, eight transmit antennas with code rate one and 3/4. Weifen Su and Xian-Gen Xia investigated matrices undertaking code rate of 7/11 and 3/5 for 5 and 6 transmit antennas. Previously 5,6,7 and 8 transmit antennas matrices of code rate with 2/3, 2/3,5/8, and 5/8 proposed. This paper intends new matrices for 5,6,7 and 8 transmit antennas with full code rate(high bandwidth efficiency).

High-Rate and Low-Complexity Space-Time Block Codes for <inline-formula> <tex-math notation="LaTeX">$2 \times 2$</tex-math> </inline-formula> MIMO Systems

The main design criteria for space-time block codes (STBCs) are the code rate, diversity order, coding gain, and low decoder complexity. In this letter, we propose a full-rate full-diversity STBC for $2 \times 2$ multiple-input multiple-output (MIMO) systems with a substantially lower maximum likelihood (ML) detection complexity than that of existing schemes. This makes the implementation of high-performance full-rate codes feasible for practical systems. Our numerical evaluation shows that the proposed code achieves significantly lower decoding complexity while maintaining a similar performance compared to that of existing rate-2 STBCs.

Analysis of Rate One Quasi-Orthogonal Space-Time Block Coding over Rayleigh Fading Channel

Full-rate is very important in any data transmission coding. For transmitting data at low bit rate than full-rate code, higher modulation scheme is required. But it is impossible to design full rate orthogonal designs with complex constellation for more than two transmit antennas. Only Alamouti code provides full-rate for two transmit antennas. In this paper, Bit Error Rate (BER) is calculated for Quasi-Orthogonal Space-time Block Coding (QOSTBC). Here we work with Rayleigh fading channel. We consider the codes which decodes pairs of symbols instead of simple separate decoding like Orthogonal Space-Time Block Coding. In Quasi-Orthogonal Space-time Block Code full-rate is achieved but full-diversity is sacrificed. Diversity is the most important techniques for providing reliable communication over fading channels. One of the diversity techniques that uses multiple transmit and/or receive antennas is space diversity. Multiple antenna technique provides a space diversity to struggle with the fading without necessarily sacrificing bandwidth resources, so the excellent solutions of removing the fading of the channel for broadband wireless communications is using space diversity. Then, with the constellation rotation of the symbol, rotated version of Quasi-Orthogonal Space-Time Block Code is generated. It provides full diversity. We simulate BER for QOSTBC, rotated QOSTBC, orthogonal STBC and for uncoded system. The simulation result shows that QOSTBC and rotated QOSTBC perform better than other systems. It shows that QOSTBC provides a full transmission rate but that rotated QOSTBC provides the full rate with the full diversity.

Improved Super-Orthogonal Space-time Trellis Coded MIMO-OFDM System

In this paper, we propose two full rate space-time coding schemes for multiple-in multiple-out (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The first proposal called extended super-orthogonal space-time code is designed based on constellation rotation for two transmit antennas. The second proposal called super-quasi orthogonal space-time trellis code combines quasi-orthogonal space-time block code with trellis code to provide full rate code for four transmit antennas. The designed space-time coded MIMO-OFDM systems achieve high diversity order with high coding gain by exploiting the diversity advantage of frequency selective fading channels.

Wireless Robotics: Generalization of an Efficient Approach with Multi-h CPM Signaling and L2-Orthogonal Space-Time Coding

Wireless Robotics has become an important research topic in the last two decades. The need of controlling a robot to perform tasks remotely has significantly increased with the number of applications in fields like medicine and military, among many others. Taking advantage of current standards like Bluetooth and Wifi, Wireless Robotics calls for low power consumption components, robustness and high data rate through the wireless channel. This call can be fulfilled with a reliable signaling format, satisfying the needs of low power consumption and high spectral efficiency. Besides, continuous phase modulation (CPM) has gained increasing attention due to its favorable trade-off between power and bandwidth efficiency. Multi-h CPM recently appeared as a generalization of single-h schemes so as to further decrease the need for bandwidth expansion over the wireless channel. Despite the interesting characteristics of CPM, the decoding of the received signal is particularly difficult in a multi-path wireless environment with no diversity. To provide some level of diversity, several authors have proposed to combine CPM with space-time block coding. A new family of codes for CPM, based on $$L^2$$ -orthogonality was recently introduced in Hesse et al. (IEEE Trans Commun 59(11): 3158---3166, 2011). These full rate codes achieve full diversity and a low decoding complexity. In this paper, we detail a non trivial extension of these $$L^2$$ -orthogonal space-time codes using multi-h signaling schemes. These new codes still achieve full diversity but a better spectral compactness by utilizing the available communication bandwidth more efficiently. Also, the decoding complexity is greatly decreased by using only one correlation filter bank for the detection of all transmitted signals.

Implementation of variable bitrate data hiding techniques on standard and proposed GSM 06.10 full rate coder and its overall comparative evaluation of performance

Paper deals with implementation of variable bit rate steganographic data transmission over ETSI GSM 06.10 FR coder at five different bitrates. Then, few modifications are suggested in Regular Pulse Excitation section of ETSI GSM FR coder which ultimately claims to produce state of the art proposed GSM FR coder. In contrast with ETSI GSM FR coder, proposed coder also exhibits same bit rate steganographic data transmission. Here, in order to facilitate the same, few RPE pulses are identified and being utilized for embedding and hiding the information bits into them. Key element of this research is to allow for joint speech coding and data hiding and that is accomplished with two different approaches like Fixed and Joint Approach. These both approaches are implemented on both Standard and Proposed coders for their overall analytical evaluation of performance using Subjective (Mean opinion Score and Degraded MOS) and Objective (Perceptual Evaluation of Speech Quality) analysis. Small data information is represented as stego signal which can be embedded over different encoded wave files (chosen from NOIZEUS corpus) that serve as carrier signal. Simulation results for both coders reveal the trade off between data embedding rate and recovered speech quality (for both approaches). It is quite evident from both Subjective and Objective analysis that proposed coder offers comparable performance at the same time with lesser simulation delay because of its inherent constructional difference. It remains the fact that for both the coders, Joint approach performs better but at the cost of more simulation delay.

L2-Orthogonal ST-Code Design for CPM

Non-linear modulations, like the Continuous phase modulation (CPM) with its constant envelope property, have been appealing for energy efficient communication systems. In parallel, linear orthogonal Space-Time block codes (STBC) have emerged as a simple way of achieving spectral efficiency by full diversity and simple decoupled maximum-likelihood decoding. However, linear codes rely on pointwise orthogonality which leads to a well-known degradation of data rate for more than two antennas. In this paper, we introduce the concept of L2-orthogonality for non-linear Space-Time codes (STC). Our approach generalizes code design based on pointwise orthogonality. Namely, we are able to derive new codes with the same advantages as pointwise orthogonal STBC, i.e. low decoding complexity and diversity gain. At the same time, we are no longer limited by the restrictions of pointwise orthogonal codes, i.e. the reduction in data rate. Actually, we show how to construct full rate codes for any arbitrary number of transmit antennas. More precisely, a family of codes for continuous phase modulation (CPM) is detailed. The L2-orthogonality of these codes is ensured by a bank of phase correction functions which maintains the phase continuity but also introduces frequency offsets. We prove that these codes achieve full diversity and have full rate. Moreover, these codes don't put any restriction on the CPM parameters.

A Linear Programming Receiver for Blind Detection of Full Rate Space-Time Block Codes

We present a new approach to the blind detection of full rate space-time block coded transmissions. Our method is based on linear programming and is globally convergent. We exploit the implicit structure of space-time block codes to cast the problem as linear programming to be solved efficiently. Unlike several known methods, the proposed technique is applicable to full-rate space-time block codes such as the popular Alamouti orthogonal code and the quasi-orthogonal space time code. Moreover, we utilize the code structure of these full rate codes to achieve simultaneous detection of all coded data streams without relying on successive schemes that are prone to error propagation. For orthogonal space-time codes, our algorithm allows near maximum likelihood detection of orthogonal codes without channel knowledge. We also can generalize the application of the proposed receiver to be used with nonorthogonal codes. Our proposed algorithm can provide performance competitive with existing techniques without imposing any conditions on the number of receive antennas.

Full Rate Space Time Codes for Large Number of Transmitting Antennas with Linear Complexity Decoding

Among the specification of the 5G networks two crucial aspects are the support of fast mobility and high data rates. With fast mobility, the fading channels phenomenon become crucial, resulting in the need for multiple input/output channel to create spatial diversity. Space time codes (STC) have been shown to be well used with the Multiple Input Multiple Output channel. The Orthogonal STC (OSTC) family of codes is known to achieve full diversity as well as very simple implementation of the Maximum Likelihood (ML) decoder. However, it was also proven that with a complex symbol constellation one cannot achieve a full rate code when the number of transmitting antennas is larger than two. Quasi-OSTC (QSTC) can have full rate even for more than two transmitting antennas but with the penalty of decoding complexity which becomes severe if the constellation size is large. In order to tackle this inherent drawback of the OSTC/QSTC and to be able to support the 5G high data rate demand, we have come up with a different STC code that, when used with a new transmission and decoding methods, achieves full rate while maintaining linear complexity decoding for any number of transmit antennas. It can also be shown that when the transmitter knows the strongest channel (through minimal feedback) the code also achieves full diversity along with better error rate than the OSTC and the QSTC.

A novel rate-2 full diversity algebraic space-time code

Orthogonal space-time block codes (OSTBCs) have attracted considerable attention due to their low complexity linear decoding and full diversity in Rayleigh fading channels. However, OSTBCs exist only for certain numbers of transmit antennas and do not provide full code rate when more than two transmit antennas are used. In this paper, a novel rate-2 algebraic space-time code that combines coordinate-interleaving and group precoding is proposed. By properly choosing the designed parameters, the coding scheme can achieve full diversity order and high coding gain. The receiver adopts polynomial complexity sphere decoding algorithm to get maximum likelihood (ML) performance. Analysis and simulations illustrate that the new code exhibits significant performance gain over the conventional OSTBCs and diagonal algebraic space-time code.

A Novel Blind Channel Estimation for a 2x2 MIMO System

A novel blind channel estimation method based on a simple coding scheme for a 2 by 2 multiple input multiple output (MIMO) system is described. The proposed algorithm is easy to implement in comparison with conventional blind estimation algorithms, as it is able to recover the channel matrix without performing singular value decomposition (SVD) or eigenvalue decomposition (EVD). The block coding scheme accompanying the proposed estimation approach requires only a block encoder at the transmitter without the need of using the decoder at the receiver. The proposed block coding scheme offers the full coding rate and reduces the noise power to half of its original value. It eliminates the phase ambiguity using only one additional pilot sequence.

An Efficient Selective Receiver Switching Scheme for STBC with Full Code Rate and Non Orthogonal Design

In the design of Space Time Block Coding (STBC), for an arbitrary complex signal constellation with a size above 2 as well as a real signal matrix with a size above 8, it is difficult to acquire full code rate and full transmit diversity simultaneously. In this letter, an efficient selective receiver switching scheme is proposed for STBC with the full code rate and non-orthogonal design with the example of a 4-by-4 matrix. In the proposed scheme with the aid of beamforming, we divide the received signals into two groups according to the encoded matrix. By this way, we can eliminate the interference from the neighboring signals by more than half.

Distributed information-lossless space-time codes for amplify-and-forward TH-UWB systems

In this paper, we extend the non-orthogonal amplify-and-forward (NAF) cooperative scheme to the context of impulse radio ultra-wideband (UWB) systems. In particular, we consider the problem of distributed space-time (ST) coding with 2D pulse position modulations (PPM) and joint pulse position and amplitude modulations (PPAM) and we propose the first known family of full-rate codes that are information-lossless with these constellations. Being totally-real, these codes are adapted to the carrier-less nature of the UWB transmissions and they outperform all previously known totally- real constructions with any number of relays. With binary PPM, they satisfy all the construction constraints of the optimal complex-valued codes proposed in [S. Yang and J.-C. Belfore, 2007] as well as the additional constraint of being real-valued.

Selective receiver switching scheme for space time block coding with full code rate and non-orthogonal design

It is desirable to construct a transmission matrix with full code rate as well as full transmit diversity in the design of space time block coding (STBC). For an arbitrary complex constellation, only full rate and full diversity signal matrix with size 2 by 2 is possible, said as Alamouti Code. For a real signal matrix with a size above 8 by 8, it is also impossible to acquire full code rate and full transmit diversity simultaneously. An efficient selective receiver switching scheme is proposed for STBC with the full code rate and non-orthogonal design. In the proposed scheme with the aid of beamforming, the authors divide the received signals into two groups according to the encoded matrix. By this way, the authors can eliminate the interference from the neighbouring signals almost by half. The simulation results with the example of matrix demonstrate that the proposed scheme can provide the improved performance and more under imperfect channel estimation.

Full-rate full-diversity 2 x 2 space-time codes of reduced decoder complexity

Multiple-input multiple-output (MIMO) techniques have become an essential part of broadband wireless communications systems. For example, the recently developed IEEE 802.16e specifications for broadband wireless access include three MIMO profiles employing 2x2 space-time codes (STCs) and two of those are mandatory on the downlink of Mobile WiMAX systems. Conventional approaches to STC design are based on performance criteria such as coding gain, diversity gain, multiplexing gain, and ignore the decoder complexity. In this paper, we take an alternative approach and present a full-rate full-diversity 2x2 STC design leading to substantially lower complexity of the optimum detector than existing schemes. This makes the implementation of high performance full-rate codes realistic in practical systems.

Some Designs of Full Rate Space–Time Codes With Nonvanishing Determinant

In this correspondence, we first present a transformation technique to improve the normalized diversity product for a full rate algebraic space-time block code (STBC) by balancing the signal mean powers at different transmit antennas. After rewriting a cyclic division algebra structure into a multilayer structure for a full rate code, we show that the normalized diversity product of the transformed code with the multilayer structure is better than the one of the transformed code with the cyclic division algebra structure. We then present a new full rate algebraic STBC with multilayer structure with nonvanishing determinant (NVD) for three transmit antennas when signal constellation is carved from QAM. We show that the new code has larger normalized diversity product than the existing 3 times 3 NVD full rate STBC for quadrature amplitude modulation (QAM) signals, and we also show that it has the largest normalized diversity product in a family of full rate STBC.

On Space–Time Coding With Pulse Position and Amplitude Modulations for Time-Hopping Ultra-Wideband Systems

In this work, we propose novel families of space-time (ST) block codes that can be associated with impulse radio ultra-wideband (IR-UWB) communication systems. The carrier-less nature of this nonconventional totally real transmission technique necessitates the construction of new suitable coding schemes. In fact, the last generation of complex-valued ST codes (namely, the perfect codes) cannot be associated with IR-UWB systems where the phase reconstitution at the receiver side is practically infeasible. On the other hand, while the perfect codes were considered mainly with quadrature amplitude modulation (QAM) and hexagonal (HEX) constellations, IR-UWB systems are often associated with pulse-position modulation (PPM) and hybrid PPM-PAM (pulse-amplitude modulation) constellations. In this paper, instead of adopting the classical approach of constructing ST codes over infinite fields or for the perfect codes), we study the possibility of constructing modulation-specific codes that are exclusive to PPM and PPM-PAM. The proposed full-rate codes are totally real, information lossless, and have a uniform average energy per transmit antenna. They permit to achieve a full diversity order with any number of transmit antennas. In some situations, the proposed schemes have an optimal nonvanishing coding gain and satisfy all the construction constraints of the perfect codes in addition to the constraint of being totally real. Simulations performed over realistic indoor UWB channels showed that the proposed schemes outperform the best known codes constructed from cyclic division algebras.

Super‐orthogonal space–time trellis codes for two transmit antennas in fast fading channels

AbstractSuper‐orthogonal space–time trellis codes (SOSTTC) are full rate, full diversity space–time codes with high coding gains for quasi‐static fading channels. In this paper, this design approach is extended to fast fading channels and new SOSTTC are proposed for BPSK and QPSK modulations based on the design criteria valid for this type of channels. The new full rate codes have 4‐ and 16‐state trellises for BPSK and QPSK cases, respectively, to avoid parallel transitions which restrict the error performance. The frame error performances are evaluated through computer simulations and it is shown that the proposed codes have superior performance in the fast fading case compared to their counterparts previously given in the literature for fast and quasi‐static fading channels. Copyright © 2007 John Wiley & Sons, Ltd.

Closed-loop space time block coding techniques for OFDM based broadband wireless access systems

We propose a closed loop space time block coding technique using four antennae at the transmitter for the enhancement of link layer performance of orthogonal frequency division multiplexing (OFDM) based broadband wireless access systems such as wireless local area networks (WLANs) and wireless metropolitan area networks (WMANs). Since full code rate and complex valued space-time block codes (STBCs) do not exist for more than two transmit antennae, we propose two feedback based STBC schemes. In the first scheme, phases of certain symbols in each sub carrier are rotated according to the feedback from the receiver. In the second scheme, best two out of four antennae are activated for transmission based on the associated channel gains in each subcarrier. In both schemes, the channel perceived at the receiver becomes orthogonal and the transmit diversity gain is maximized. One of the major challenges associated with the closed loop STBC schemes in OFDM systems as compared to CDMA systems is the requirement for extensive channel state information feedback as channel orthogonalization is performed in each subcarrier. However, by exploiting the feedback correlation among subcarriers, we have proposed a group based quantization technique to reduce feedback overhead significantly, making this scheme very attractive to broadband wireless access systems.