SSB Systems Research Articles

Optical Single-Sideband Transmitters

Optical single-sideband (SSB) transmission technique fills the gap between intensity-modulation/direct-detection (IM/DD) and digital coherent transmission technologies. It provides a cost-effective solution to overcome the transmission distance limitation induced by fiber chromatic dispersion in IM/DD system at the expense of increased complexity of the transmitter (Tx) structure and receiver-side signal processing. This makes optical SSB system become a promising candidate for cost- and latency-sensitive datacenter interconnects. Previous research on optical SSB system mainly focused on improving the spectral efficiency and receiver sensitivity, whereas the increased complexity and cost of optical SSB Tx were overlooked. In this paper, we present a comprehensive review of the recent advances in the optical SSB Tx. First, we evaluate three conventional optical SSB Tx schemes based on optical filter, in-phase/quadrature modulator, and dual-drive Mach-Zehnder modulator. We then introduce the recently proposed optical SSB Tx schemes based on electro-absorption modulation lasers (EMLs), including the double-sided EML, two-segment EML, and the dually modulated EML. Compared with the conventional optical SSB Tx solutions, the EML-based schemes exhibit obvious friendliness to monolithic integration. Besides, we investigate the practical ways to add optical carrier with optical SSB signal and efficient implementation of the Hilbert transform, which are two practical issues in the optical SSB Tx. Finally, we explore the capability of monolithic integration of optical SSB Tx with state-of-the-art material platforms. Our comparison made among these schemes can provide a guideline for the selection of proper Tx scheme for specific optical SSB systems.

6.4Tb/s SSB WDM Transmission Over 320km SSMF With Linear Network-Assisted LSTM

Single-sideband (SSB) signaling is a promising technology for short and medium reach optical transmission. We propose a novel architecture of linear network-assisted long short-term memory network (LN-LSTM) to mitigate optical transmission impairments in SSB systems. With a combination of a linear network and an input-pruned LSTM network, LN-LSTM achieves better performance and lower computation complexity compared with conventional LSTM equalization. With LN-LSTM, we achieve 6.4 Tb/s ( $32\times 200$ Gb/s) wavelength division multiplexing (WDM) SSB transmission over 320km standard single-mode fiber (SSMF) with a bit error rate (BER) below the 20% soft-decision forward error-correction (SD-FEC) threshold of $2.4\times 10^{-2}$ .

A 3D Cross‐Linking Lithiophilic and Electronically Insulating Interfacial Engineering for Garnet‐Type Solid‐State Lithium Batteries

AbstractSolid‐state batteries (SSBs) promise high energy density and strong safety due to using nonflammable solid‐state electrolytes (SSEs) and high‐capacity Li metal anode. Ta‐substituted Li7La3Zr2O12 (LLZT) SSE possesses superior ionic conductivity and stability with Li metal, yet the interfacial compatibility and lithium dendrite hazards still hinder its applications. Herein, an interfacial engineering is demonstrated by facile acid‐salt (AS) treatment on LLZT, constructing a 3D cross‐linking LiF‐LiCl (CF) network. Such structure facilitates Li wetting via capillary permeation. Notably, CF as electronically insulting phases block the electrons through the interface and ulteriorly suppress the dendrite formation. The assembled Li symmetric cell exhibited a low interfacial impedance (11.6 Ω cm2) and high critical current densities (CCDs) in the time‐constant mode, 1.8 mA cm−2 at 25 °C and 3.6 mA cm−2 at 60 °C, respectively. Meanwhile, by exploring the capacity‐constant mode of CCD measurement, the concept of critical areal capacity (CAC) is first proposed, obtaining its values of ≈0.5 mAh cm−2 at 25 °C and 1.2 mAh cm−2 at 60 °C. Moreover, the safety‐enhanced hybrid SSBs matched with LiFePO4 and LiNi0.6Co0.2Mn0.2O2 deliver a remarkable rate and cycling performances, validating the feasibility of this interfacial engineering in various SSB systems.

SSB Single Carrier and Multicarrier in C-Band FSO Transmission With KK Receiver

With the increasing demand of bandwidth, a higher capacity communication system is required for optical short link and access network. Intensity modulation/direct detection (IM-DD) is considered as a reasonable method in access network, due to its low cost and power consumption. However, it reduces the spectral efficiency compared with IQ modulation. In addition, single-sideband (SSB) signal occupies less bandwidth than double-sideband signal (DSB). However, SSB systems suffer from signal-signal beat interference (SSBI) from photodiodes (PDs). Recently, Kramers–Kronig (KK) receiver is proposed to mitigate SSBI. Meanwhile, single-sideband (SSB) signal is the prerequisite for KK scheme, and this kind of signal is also tolerant to fiber chromatic dispersion and multipath-fading. On the other hand, free-space optical (FSO) communication is becoming a promising candidate for next generation optical access network. Thus we experimentally demonstrate the KK scheme in 20 km SSMF and 20 m FSO links with both single carrier signal and multicarrier signal. We compare the performance between them with and without pre-equalization (pre-EQ). With the help of probabilistically shaped (PS) mapping to gives an increase in the sensitivity over an additive white Gaussian noise (AWGN). We reach a 117bit/s transmission with a spectral efficiency of 5.85 bit/s/Hz of 20 Ghz bandwidth with single modulator and single photodiode (PD) in fiber-FSO system.

Theoretical CSPR Analysis and Performance Comparison for Four Single-Sideband Modulation Schemes With Kramers-Kronig Receiver

Recently, high-speed optical transmission using single-side-band (SSB) modulation with Kramers-Kronig (KK) scheme has gained great attention due to its high spectral efficiency (SE) and capability of electronic chromatic dispersion compensation (CDC), which can be widely employed in optical metro networks as a promising transmission scheme. To our knowledge, the carrier-signal power ratio (CSPR) is the key parameter to SSB-based systems and the optimum CSPRs can vary distinctly in different SSB modulation schemes. In this paper, the SSB-based KK systems with four kinds of SSB signal generation schemes are investigated, i.e. optical carrier-assisted SSB (OCA-SSB), virtual carrier-assisted SSB (VCA-SSB), SSB subcarrier modulation (SSB SCM) with IQ modulator (IQM) and with dual-drive Mach-Zehnder modulator (DDMZM) respectively. Here, the detailed theoretical derivations of these modulation processing are given and the theoretical relationship between device parameters and the CSPR has been further studied for the different SSB schemes. In order to verify those theoretical analyses, a 224-Gb/s direct detection (DD) transmission with SSB 16-ary quadrature amplitude modulation (16-QAM) signal has been demonstrated based on four SSB generation methods. The results show that theoretical derivations are closely consist with numerical analysis, such as $V_{bias}$ in the scheme of SSB SCM with IQM and optical modulation index (OMI) in SSB SCM with DDMZM. Therefore, our research can provide a theoretical guidance of appropriate device parameter configuration so as to achieve the optimum performance for SSB systems.

The Implemention of a Digital SSB Modulator Based on Folding Transformation

Single-Sideband (SSB) modulation is now widely used for its high band efficiency and low power consumption. In anolog SSB systems, it is usually hard to achieve high performance due to many nonideal factors of anolog components and circuits, such as the I/Q channel mismatch and temperature drift. To overcome these disadvantages, a digtal SSB modulation system based on the Weaver method is designed in this paper. In this system we creatively use the onchip ADC of the ARM processor for audio sampling. Besides, the CORDIC algorithm and the folding transformation are also utilized to reduce hardware costs in the FPGA implemention. This paper mainly discusses the theory and implemention of the Weaver SSB modulation system, and shows the experimental results on actual hardware.

Identification and mitigation of interference sources present in SSB‐based wireless MRI receiver arrays

Single sideband amplitude modulation (SSB) is an appealing platform for highly parallel wireless MRI detector arrays because the spacing between channels is ideally limited only by the MRI signal bandwidth. However this assumes that no other sources of interference are present outside that bandwidth. This work investigates the practical interference between multiple SSB-encoded MRI signals. Noise from coil preamplifiers and carrier bleed-through are identified as sources of interference. Two different SSB systems were designed for 1.5 T with different noise filtering properties. We show how the differences between the filtered noise profiles impact the received MR signal's dynamic range (DRsig ) and image signal-to-noise ratio through simulation, bench measurements, and phantom imaging experiments. When operating individually in the MR scanner, both SSB systems were shown to minimally impact the original DRsig and signal-to-noise ratio. Conversely, when all eight channels were operating simultaneously, an average signal-to-noise ratio loss was observed to be 12% in the one system, while a second system with more complex filtering was able to achieve a 3% loss in signal-to-noise ratio. Successful wireless transmission of multiple SSB-encoded MRI signals is possible as long as channel interference is properly managed through design and simulation.

Cost-effectiveness of compression technologies for evidence-informed leg ulcer care: results from the Canadian Bandaging Trial

BackgroundVenous leg ulcers, affecting approximately 1% of the population, are costly to manage due to poor healing and high recurrence rates. We evaluated an evidence-informed leg ulcer care protocol with two frequently used high compression systems: ‘four-layer bandage’ (4LB) and ‘short-stretch bandage’ (SSB).MethodsWe conducted a cost-effectiveness analysis using individual patient data from the Canadian Bandaging Trial, a publicly funded, pragmatic, randomized trial evaluating high compression therapy with 4LB (n = 215) and SSB (n = 209) for community care of venous leg ulcers. We estimated costs (in 2009–2010 Canadian dollars) from the societal perspective and used a time horizon corresponding to each trial participant’s first year.ResultsRelative to SSB, 4LB was associated with an average 15 ulcer-free days gained, although the 95% confidence interval [−32, 21 days] crossed zero, indicating no treatment difference; an average health benefit of 0.009 QALYs gained [−0.019, 0.037] and overall, an average cost increase of $420 [$235, $739] (due to twice as many 4LB bandages used); or equivalently, a cost of $46,667 per QALY gained. If decision makers are willing to pay from $50,000 to $100,000 per QALY, the probability of 4LB being more cost effective increased from 51% to 63%.ConclusionsOur findings differ from the emerging clinical and economic evidence that supports high compression therapy with 4LB, and therefore suggest another perspective on high compression practice, namely when delivered by trained registered nurses using an evidence-informed protocol, both 4LB and SSB systems offer comparable effectiveness and value for money.Trial registrationClinicalTrials.gov Identifier: NCT00202267

Radio Interferometer Sensitivities for Three Types of Receiving Systems: DSB, SSB, and 2SB Systems

Abstract The purpose of this paper is to study the detection sensitivity suitable to the practical situation for a radio interferometer. For the radio interferometer, the three types of receiving systems are a double-sideband (DSB), a single-sideband (SSB), and a two-single-sideband (2SB) systems. The evaluation of these receiving systems is of significance to explore the best performance for a radio interferometer. In this paper, the signal-to-noise ratios of these three-type receiving systems are newly derived to investigate the performance and key features of each system. We demonstrate the system noise temperatures of SSB, 2SB, and DSB receiving systems by using the ALMA-specification receiver noise temperature and the atmosphere condition measured at the ALMA site, and present the relative sensitivities between the 2SB and DSB receiving systems at the ALMA site. From these results, we recommend the 2SB receiving system for all bands of ALMA.

Problem of speech pulling and its implementation for the design of phase-locked SSB radio systems

In the paper, the effect of speech interference on the performance of long-loop phase-locked VHF SSB radio systems is evaluated, It is shown that unless the system's reference tone is adequately protected by suitable filtering in the transmitter's audio processing, the problem of ‘speech puffing’ may occur with severe degradationin intelligibility. Furthermore, residual FM modulation of the VCO's control line (the first local oscillator) through speech interference degrades the oscillator's output spectrum with possible reduction in adjacent-channel rejection. After analysing the effect of interfering sinusoidal signals on in-lock-loop per formance, filter design criteria are established for pilot-carrier and in-band-tone SSB systems, and the theoretically predicted results are verified experimentally. Finally, alternate phase-locked receiver configurations are suggested in an attempt to overcome first-oscillator spectrum degradation in long-loop receivers.

The effect of fading and shadowing on channel reuse in mobile radio

Co-channel interference probabilities are calculated for mobile radio systems operating in a Rayleigh fading lognormal shadowing environment with inverse fourth power law dependence of area mean signal level on range. Interference levels are shown to be high even with generous reuse distances. The results are used to calculate spectrum utilization using reasonable but tentative estimates of protection ratio and channel spacing for SSB systems. On this basis SSB offers a higher spectral efficiency than current 25 kHz spaced FM systems.

A Unified Approach to Pulse Design in Data Transmission

The problem of designing optimum pulseshapes for data transmission over randomly selected channels is examined using a meansquared error criterion. Earlier work has focused principally on SSB or VSB systems in the presence of timing and carrier phase jitter, but we extend the results here to any two-dimensional signaling scheme (including as special cases SSB, VSB, combined AM-PM, QAM, and staggered QAM) and to any type of channel dispersion. By imposing certain mild constraints on the transmitter and receiver filters, it is seen that one can solve for optimum pulses more easily than with earlier approaches, and yet the resulting system is still essentially optimum. These constraints leave design freedom only in the rolloff bands of the pulse spectra, and a major thurst of the work is to design for optimal utilization of whatever excess bandwidth is available. The approach used involves immunity to channel distortions: only the type of channel distortion to be encountered is known, and series expansions of mean-squared error are used to find sensitivity coefficients. These coefficients are then minimized by proper signal design. Closed form expressions are found for the optimum pulses, and these results are compared with previous work. A second approach, which uses as its criterion the mean-squared error averaged over all possible channel characteristics, is also discussed.

Effect of Recorder Time-Base Error on an AM-Baseband Telemetry System

A model of the demodulation portion of a suppressedcarrier AM-baseband telemetry system, incorporating the effect of tape recorder flutter, is developed. The carriers necessary for demodulation are derived from a single pilot by translation to the appropriate frequencies. The analysis illustrates how flutter affects system performance and shows that the effect is similar for both SSB and DSB systems. Minimization of error in the demodulated signal requires that filters in the data channels and the pilot channel have linear phase characteristics with identical slopes. The Appendix outlines the mathematical description of flutter for both predetection and postdetection recording and illustrates that the model is appropriate for analyzing both cases if the peak flutter is small.

Jamming of Communication Systems Using FM, AM, and SSB Modulation

Jamming of voice communication systems is a very ungrateful task and ``brute force'' jammers have to be used, while other systems, such as radar, can be jammed effectively using low power but sophisticated jammers. Geographical situation is very much against the jammer, particularly in ground-based mobile communication systems. The propagation of ground wave is such that a rapid increase of jamming power is required, as the ratio of distances of the jammer to the desired transmitter increases. The jammer is never certain whether or not the communication network is jammed and is never actually able to jam the communications completely. It can only limit the operating range of the system. Different modulation systems are considered and the necessary power density for jamming of each system is discussed. It is concluded that effective jamming of FM systems and other systems with threshold systems is easier than that of AM and, particularly, the SSB systems. However, for nuisance jamming, the opposite is true. Finally, the jamming of the SSB systems is considered in more detail and it is proven that the so-called reduced-carrier SSB systems are not easier to jam than systems with a completely suppressed carrier.

Equipment Configuration and Performance Criteria for Fully Optimized Tropospheric-Scatter Systems

The "optimum" system is examined with the aid of a basic equation related to channel SNR. Expressions are then developed which show that for equal channel loading and capacity, FM systems are likely to be superior to SSB systems for normal voice channel operation. Further improvement in FM performance may be achieved with "phase-locked" receivers. Performance equations for such receivers are used in basic expressions for optimized scatter circuits to express channel capacity as a function of maximum distance for minimum power. From this equipment configurations for various performance capabilities are developed. These data then give the maximum capability of the tropospheric scatter system when all relevant design parameters are optimized. It is suggested that long-haul toll performance criteria should be based on six tandem links. This leads to a per-link requirement for channel signal-to-weighted thermal noise ratio with quadruple diversity operation of 45.7 db, and 53 db for the channel signal-toweighted nonlinear noise ratio. Difficulties in the measurement of thermal noise are discussed. It is believed that a suitable approach is to specify single-link performance in terms of a distribution obtained with one-to-two minute averaged samples. Data are also developed for the minimum permissible system bandwidth and the transmitted spectrum as a function of channel capacity. Finally, it is considered that the performance in multilink multichannel circuits may be limited by nonlinear noise introduced by multipath effects related to selective fading. In this respect, further research is necessary in order to obtain reliable computational techniques for the intermodulation noise associated with the multichannel system.

Considerations in SSB and ISB systems for long-distance radiotelegraph communications

Single side-band (ssb) and independent side-band (ISB) radiotelegraph systems allow for a high degree of frequency-division multiplexing as contrasted to the requirement for time division multiplexing in usual frequency shift keyed carrier systems. This advantage is the principal justification for its use, especially for those circuits requiring high-speed traffic-handling capacities.

A Mathematical Analysis of the Kahn Compatible Single-Sideband System

A system has been proposed by Kahn for the generation of an SSB signal which may be received on an AM receiver without distortion in the receiver output signal. For this reason, the system is said to be a "compatible" SSB system. The mathematical analysis of this system is fairly simple except for that part of the circuit which performs a limiting of the input full-carrier SSB signal. It is shown that Granlund has analyzed circuits of this type in great detail and that the results of Granlund's work can be used in a very direct manner to obtain a fairly complete analysis of the Kahn system. From the resulting analysis, computations are made of the CSSB signal spectra for various input signal conditions. The theoretical results are also used to predict certain system operating characteristics. The results obtained are presented without comment as no attempt is made to evaluate the Kahn system relative to other compatible SSB systems which have been proposed.

An Introduction to Single-Sideband Communications

The elements of the SSB communication system and its advantages over the AM system are discussed. These advantages include benefits to the individual user, generally in the form of reduced size and weight of equipment or more effective communication when conditions limit the size of the installation, and benefits to the radio environment which include spectrum conservation and reduction in the total radiated power required to accomplish a given communication function. Particular attention is devoted to the areas in which problems still remain in the use of SSB techniques in hf communication. Many of these problems arise from the necessity of having a suitable demodulating carrier at the receiver, and include the desirability of having highly accurate and stable frequency control of the transmitter and receiver, complex techniques for frequency synthesis, and techniques for carrier transmission and receiver afc. Other problems include compatibility between AM and SSB systems during the transition period, and standardization of SSB practices.

Comparison of SSB and FM for VHF Mobile Service

Mobile SSB and fm systems are compared on the basis of the same equipment size. The influence of the speech processing on the comparative results is discussed. It is concluded that SSB may provide a somewhat better range of operation with considerable spectrum saving but the signal-to-noise ratio in strong signal areas will be poorer.