Research of some properties of alphabets based on mutually orthogonal broadband signals

With the broadband, noise-like, and non-periodic characteristics of chaotic signals, chaotic digital modulation schemes have received extensive attention. A new short reference orthogonal double bit rate differential chaotic shift keying (SR-ODBR-DCSK) communication scheme is proposed in the paper. The modulation technology generates two orthogonal chaotic signals by using the orthogonality of the chaotic signals acting on the Walsh function and modulates the continuous two-bit data information respectively to achieve the simultaneous transmission of two signals at the same time slot. Odd information bits and even information bits are modulated to two orthogonal signals so as to reach a double transmission rate on the basis of the original channel. In this paper, the performance of SR-ODBR-DCSK in the additive white Gaussian noise (AWGN) channel is analyzed, and a Monte Carlo simulation test is carried out. The bit error rate of this modulation method is compared with that of SR-DCSK. The results show that the SR-ODBR-DCSK system is excellent and promising.

The orthogonal polarized signals are widely used in millimeter-wave applications such as in radar, communications, remote sensing and radiometry. The diplexing (i.e., combination or separation) of the orthogonal signals is imposed on the components, which are usually called as orthomode transducers (OMTs). In general, the OMT has three physical ports, though it exhibits properties of a four-port device, because the common port, usually with a square or circular cross section, provides two electrical ports that correspond to the independent orthogonal polarized signals. In modern systems, requirements to the OMT are a high cross-polarization discrimination between the orthogonal signals and a good match of all electrical ports. In the millimeter-wave range, it is a difficult problem to design and produce OMT meeting to the required specification, because of dimensions of the components are very small. Therefore, the development of a new OMTs design suitable for mm band is an important task. In the present report we consider a narrowband OMT design that suits most applications in radar and radio-relay link systems.

In this Letter, performance analysis of an impulse radio (IR) ultra wideband (UWB) correlation based receiver utilising non‐coherent detection of orthogonal signalling is provided. The receiver's performance is presented through analysis and simulations in the additive white Gaussian noise (AWGN) channel. Results which show that in non‐coherent detection of binary orthogonal signalling there is a difference between the traditional narrowband and IR approaches are provided. In the narrowband communication, there is a well‐known, approximately 1 dB, difference between coherent and non‐coherent orthogonal signal detection in AWGN. It is demonstrated here that in the binary orthogonal signalling of IR receiver the difference between coherent and non‐coherent detection is insignificant, only tenths of decibels. This can be significant piece of information while considering different receiver structures for wireless sensor networks.

The problem of binary orthogonal signaling over a Gaussian noise channel with unknown phase/fading is considered. By viewing the problem in a rotated coordinate system, the orthogonal signal structure is considered as the combination of an antipodal signal set and a pilot tone for channel measurement. For data detection the optimum matched-filter envelope-detector is shown to be identical to a novel detector-estimator receiver in which the detector performs partially coherent detection, using an absolute coherent reference generated by the estimator from the channel measurement provided by the pilot-tone component of the orthogonal signal structure. This detector-estimator interpretation shows that it is incorrect to refer to the optimum receiver as a noncoherent receiver. It also leads to the development of new approaches for analyzing the error probability of the receiver. An exponential Chernoff upper bound is obtained for the Rician channel.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The orthogonal signal structure has been shown to be the superposition of an antipodal signal set and an unmodulated (pilot tone) component which can be used for channel measurement. Starting from this point of view, the quadratic receiver for orthogonal signals over the Gaussian channel with unknown phase/fading has been shown to be equivalent to a detector-estimator receiver. The estimator makes an optimum estimate of the unknown complex channel gain based on the channel measurement provided by the unmodulated component of the received signal. This channel estimate then forms a (partially) coherent reference for the detector in detecting the data carried by the antipodal signaling component of the received signal. This paper exploits this detector-estimator structure of the quadratic receiver, and generalizes it to a receiver in which the estimator makes an estimate of the channel gain in each signaling interval based on the totality of signals received over all the signaling intervals or a subset of these intervals. The generalized quadratic receiver is just as simple to implement as the conventional quadratic receiver, and theoretical and simulation results show that it can achieve substantial performance gains over the conventional receiver. A theory is presented to show that the generalized quadratic receiver is an implementable approximation to the optimum symbol-by-symbol receiver for uncoded orthogonal signals over the Gaussian channel with unknown phase/fading. The theory shows that the structure provides a unified and systematic approach to the design of coherent symbol-by-symbol receivers, and shows that the conventional carrier-loop-type receivers are ad hoc.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

In this paper we study the use of repeat- puncture superorthogonal convolutional turbo codes in an additive white Gaussian noise (AWGN) channel. The performance of turbo codes (TC) have been shown to be near the theoretical limit in the AWGN channel. By using orthogonal signaling, which allows for bandwidth expansion, the performance of the turbo coding scheme can be improved even further. Since this is a low-rate code, the code is mainly suitable for spread-spectrum modulation applications. In classical turbo codes the frame length is set equal to the interleaver size, however, the codeword distance spectrum of turbo codes improves with an increasing interleaver size. It has been reported that the performance of turbo codes can be improved by using repetition and puncturing. Repeat-puncture turbo codes (RPTC) have shown a significant increase in performance at moderate to high signal-to-noise ratios. In this paper, we study the use of orthogonal signaling and parallel concatenation together with repetition and puncturing to improve the performance of superorthogonal convolutional turbo codes for reliable and effective communications. Simulation results in AWGN channel are presented together with analytical upper bounds, which have been derived using transfer function bounding techniques.

Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Abbott Background Ventricular tachycardia (VT) in patients with structural heart disease (SHD) is related to scar and slow conduction areas. Substrate-based ablation has become the gold standard treatment in patients with SHD-related refractory VT. A new high-density grid shaped catheter that allows simultaneous analysis of adjacent orthogonal bipolar signals can allow better understanding of these slow conduction areas with the potential to improve ablation results. Purpose This was a prospective, multicenter observational study to characterize the utility of electroanatomical mapping with a high density grid-style mapping catheter (HD Grid) in subjects undergoing catheter ablation for ventricular tachycardia (VT) in real-world clinical settings. Methods During the study period, patients who underwent VT ablation using the HD Grid catheter as the primary mapping catheter were included. Comparisons both during the procedure and retrospectively were performed between conventional electrode configuration maps and simultaneous orthogonal bipole electrode configuration maps. The influence of these different configurations on ablation strategy was analyzed. Results During study period (January 2019 – April 2020) 57 maps were performed in 34 VT subjects (average age: 64.3yr, male: 85.3%, ischemic cardiomyopathy: 70.6%). The left ventricle was mapped in 94.1% of subjects, including left ventricular outflow tract and papillary muscles in 20.6% and 8.8% respectively, reporting minimal or no ectopic beats in 97.1% of the subjects. The total number of mapping points collected was 14172.0 ± 15174.8 in 24.3 ± 17.9 min per map. Simultaneous orthogonal bipole mapping identified differences in 67.6% of maps compared to linear along-the-spline electrode configurations. The differences consisted mainly in the surface area (92%) and location of low voltage (40%). When compared during the procedure, simultaneous orthogonal bipole mapping was used to identify ablation strategy in 100% of cases. When compared to a standard along-the-spline configuration retrospectively, the ablation strategy identified with simultaneous orthogonal bipoles was different in 30.1% of cases. The ablation strategy used in these subjects was mainly substrate ablation (late potentials and low voltage areas in scar regions) with an acute success rate of 97.1%. Conclusions The use of the HD Grid catheter with the ability to analyze orthogonal signals is feasible and has the potential to change the ablation strategy in one third of VT patients with a high acute success rate.

The point coordination function (PCF) of the IEEE 802.11 WLAN facilitates deterministic frame transfer by a polling mechanism. This enables to support quality of service. Despite this benefit the PCF could be inefficient at low-to-medium traffic loads because it always polls all stations regardless of their actual demand. To overcome this drawback, we introduce a novel polling scheme where all stations simultaneously report their status by sending orthogonal signals, and a BS identifies and polls only those stations having data to send. The feasibility of orthogonal signalling is evaluated in a realistic channel model where multipath fading and additive white Gaussian noise are applied. Moreover, channel utilization of the proposed scheme is investigated analytically, and compared with other schemes through simulation. The evaluation results show that the proposed scheme considerably outperforms other schemes at low-to-medium traffic loads.

We obtain upper bounds on the bit-error rate (BER) for maximum-likelihood (ML) decoding of turbo codes constructed with uniform interleavers for M-ary orthogonal signals. We use transfer function bounding techniques to obtain the above bounds. Thus, the upper bounds result in the average bound over all interleavers of a given length. We apply the techniques to parallel concatenated coding (PCC) schemes where recursive convolutional codes are used as constituent codes. We present the average bounds on the BER of turbo codes with constraint length 3 for M-ary orthogonal signals on additive white Gaussian noise (AWGN) channels. We show that the performance advantage of turbo-coded 4-ary orthogonal signals over turbo-coded binary orthogonal signals is smaller than the performance advantage in the absence of coding, which is 3.0 dB.

A novel signaling scheme is presented, where a set of orthogonal signals is transmitted in parallel. The signals are selected according to the so-called residue number system (RNS). Hence the system is essentially a multiple code parallel communication scheme using high modulation alphabets. It is demonstrated that the system's performance can be substantially improved by exploiting a number of advantageous properties of the RNS arithmetic. We focus our attention on the system's description and on the associated background of the RNS arithmetic, as well as on the performance evaluation of the residue number system arithmetic, using both nonredundant and redundant moduli based orthogonal signaling schemes, over an additive white Gaussian noise (AWGN) channel. Redundant RNS codes are introduced in order to protect the transmitted information. The detection techniques used in this novel system are different from conventional detectors. Specifically, a novel decision algorithm, referred to as a ratio statistic test, is designed, which implies dropping some of the lowest reliability demodulation outputs before the residue digits are transformed back to binary symbols. This improves the system's performance. This dropping technique is different from the conventional errors and erasures decoding, where the erased symbols (or bits) should be computed and filled during decoding. We argue that the demodulated/decoded information can be obtained by decoding the retained or undiscarded symbols upon exploiting the properties of the RNS arithmetic. Our numerical results show that the proposed scheme constitutes a high-efficiency parallel transmission method for high-bit-rate communication, achieving a coding gain of 2 dB at a bit error rate of 10/sup -6/ over AWGN channels.

It is well known that a communication system using M-ary orthogonal signaling in additive white Gaussian noise can achieve capacity. However, in a worst case partial band jamming channel, orthogonal signaling fails to achieve capacity. In this paper, we show that a M-ary orthogonal system using coding and side information provides reliable communications in partial band jamming. In particular, the system can achieve capacity by using the ratio threshold test (RTT) to convert all errors due to the channel into erasures. For the worst case jamming scenario, the minimum E/sub b//N/sub J/ needed for error-free communications is shown to be 4 ln 2 (4.43 dB). The optimum code rate that minimizes E/sub b//N/sub J/ is 1/2. With hard decision decoding, the minimum E/sub b//N/sub J/ needed for error-free communications is 8 ln 2 (7.44 dB) with the optimum code rate at 1/4. Hence, asymptotically, the typical 3 dB gain obtained by using soft decisions is observed. Moreover, this gain in performance does not require additional information from the transmitter; RTT generates its side information entirely at the receiver.

To address the issues of low transmission rate and poor bit error rate (BER) performance in traditional Differential Chaos Shift Keying (DCSK) systems, this letter proposes a novel position-index-modulation-based DCSK scheme. Each row of the Walsh code matrix is used to perform a Kronecker product with the initial reference signal to generate multiple orthogonal signals. Each orthogonal signal independently undergoes position index modulation and carries modulated bits to transmit information. Position index modulation labels each time slot of each subcarrier in the system frame structure as a unique position indexed sequentially. According to the rules of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula>-combination mapping, one or more active positions are selected from all positions to transmit corresponding orthogonal signals. At the receiver, a sliding average denoising technique is introduced to reduce noise variance and enhance system reliability. Additionally, BER expressions are derived under additive white Gaussian noise (AWGN) channels and multipath Rayleigh fading channels. Simulation results demonstrate that the proposed system achieves higher transmission rates and better BER performance compared with several DCSK-based schemes proposed in recent years.

We obtain upper bounds on the bit-error rate (BER) for maximum-likelihood (ML) decoding of binary turbo-codes followed by M-ary orthogonal signal mapping through a uniform interleaver. We use the transfer function bounding techniques to obtain the above bounds. Thus, the upper bounds correspond to the average bound over all interleavers of a given length. We apply the techniques to parallel concatenated coding (PCC) schemes where recursive convolutional codes are used as constituent codes. We present the average bounds on the BER of turbo codes with constraint length 3 for M-ary orthogonal signals on additive white Gaussian noise (AWGN) channels. We show that for a given increase in interleaver length, the improvement in BER is larger for turbo-coded 4-ary orthogonal signals than for turbo-coded binary orthogonal signals. We also show that the coding gains of turbo code for M-ary orthogonal signals becomes smaller as M is increased when the block length N is short.

This chapter considers the bit error rate performance of digital signaling on frequency nonselective (flat) fading channels with additive white Gaussian noise (AWGN). We first introduce a vector representation for digital signaling on flat fading channels with AWGN. Later, a generalized analysis is provided for the error rate performance of digital signaling on flat fading channels. We then derive the structure of the optimum coherent receiver for the detection of known signals in AWGN. The error probability performance of various coherently detected digital signaling schemes is considered, including phase shift keying, quadrature amplitude shift keying, orthogonal signals, and orthogonal frequency division multiplexing. Other types of detection schemes include differential detection of differentially encoded binary phase shift keying and differentially encoded π ∕ 4-phase shifted quadrature phase shift keying. We also consider noncoherent detection of orthogonal signals. Finally, we consider coherent and noncoherent detection of continuous phase modulated signals.

The optimum detection of binary antipodal signals in additive white Gaussian noise (AWGN) channels with Gaussian channel estimation error has been studied in prior work. In this paper, we present the optimum detector based on the maximum- likelihood criterion for binary orthogonal signals in the presence of Gaussian distributed channel estimation error and AWGN. It is shown that the optimum detector is a linear combination of the optimum coherent and optimum noncoherent detectors. We derive the exact closed-form expression of the average bit error probability of the proposed optimum detector in Rayleigh fading channels with AWGN. It is found that if the variance of channel estimation error for a given average SNR is greater than a threshold, then orthogonal signalling outperforms antipodal modulation, and the analytical expression of this threshold is derived.