Showing papers on "Keying published in 2015"
TL;DR: A differential SM scheme that completely bypasses any CSI at the transmitter or receiver, while preserving the single active transmit antenna property, is developed and can be applied to any constant energy constellation such as phase-shift keying and to systems with arbitrary numbers of transmit and receive antennas.
Abstract: Spatial modulation (SM) is a newly emerging multiple-input–multiple-output technique that activates only a single antenna for transmission at any time instant and uses the index of the active antenna as an additional information-carrying mechanism. However, by its nature, SM decoding is coherent in that channel state information (CSI) is required at the receiver. In fact, coherent SM decoding can be very complex due to the heavily entangled channel estimation and symbol detection. In this correspondence, a differential SM scheme that completely bypasses any CSI at the transmitter or receiver, while preserving the single active transmit antenna property, is developed. The proposed scheme can be applied to any constant energy constellation such as phase-shift keying (PSK) and to systems with arbitrary numbers of transmit and receive antennas. Simulation results are presented under various system configurations. With the same spectral efficiency, the proposed scheme is capable of paying no more than 3 dB of signal-to-noise ratio penalty compared with coherent SM and outperforming the single-antenna differential PSK and differential space–time coding schemes.
212 citations
Patent•
08 Sep 2015
TL;DR: A portable encryption key installation system is described in this paper, which includes a portable keying device for installing a data communications encryption key in an electronic terminal. But it is not shown how to use it in a secure manner without having to remove the terminal from its shipping container or ship offsite.
Abstract: A portable encryption key installation system is disclosed that includes a portable keying device for installing a data communications encryption key in an electronic terminal. The portable keying device securely reprograms the encryption key in the electronic terminal without having to remove the terminal from its shipping container or ship the electronic terminal offsite. Furthermore, the portable keying device securely reprograms the encryption key in the electronic terminal without having to dismantle the terminal, deactivate any anti-tampering features, or re-bond the terminal.
107 citations
TL;DR: This paper investigates the average symbol error rate (ASER) performance of a dual-hop hybrid relaying system relying on both radio frequency (RF) and free-space optical (FSO) links and finds that the fixed-gain relays strategy achieves twice the diversity order of the channel-dependent relaying strategy, albeit at the cost of requiring a high power amplifier dynamic range at the relay node.
Abstract: This paper investigates the average symbol error rate (ASER) performance of a dual-hop hybrid relaying system relying on both radio frequency (RF) and free-space optical (FSO) links. Specifically, an RF link is used for supporting mobile communication, whereas an FSO link is adopted as the backhaul of the cellular infrastructure. Considering nonline-of-sight RF transmissions and a generalized atmospheric turbulence (AT) channel, the associated statistical features constituted of both exact and asymptotic moment-generating functions are derived in the closed form. They are then used for calculating the ASER of M -ary phase-shift keying (PSK), differentially encoded noncoherent PSK (DPSK), and noncoherent frequency-shift keying. A range of additional asymptotic expressions is also derived for all the modulation schemes under high signal-to-noise ratios (SNR). It is observed from the asymptotic analysis that the ASERs of all the modulation schemes are dominated by the average SNR of the RF link in the hybrid relaying system using a fixed relay gain, whereas in the relaying system using a dynamic channel-dependent relay gain, the ASERs of all the modulation schemes depend both on the average SNR and the AT condition of the FSO path. We also find that the fixed-gain relaying strategy achieves twice the diversity order of the channel-dependent relaying strategy, albeit at the cost of requiring a high power amplifier dynamic range at the relay node. Furthermore, by comparing the asymptotic ASERs, we calculate the SNR differences between the different modulation schemes in both the fixed-gain and channel-dependent relaying systems. Finally, simulation results are presented for confirming the accuracy of our expressions and observations
93 citations
TL;DR: The new system design replaces the delay circuit used in conventional DCSK systems by time-reversal operations, and the theoretical bit-error-rate expressions for additive white Gaussian noise and multipath fading channels are analytically studied and derived.
Abstract: This paper presents the design and performance analysis of an improved differential chaos-shift keying (I-DCSK) system. Instead of sending reference and data carrier signals in two time slots as in the conventional DCSK scheme, in the improved design, a time-reversal operation is used to generate an orthogonal reference signal to the data carrier signal and then sum up these two sequences into one time slot, prior to transmission. This operation reduces the bit duration to half, which doubles data rate and enhances spectral efficiency. At the receiver, the received signal is correlated to its time-reversed replica and is summed over the bit duration. The new system design proposed in this brief replaces the delay circuit used in conventional DCSK systems by time-reversal operations. Moreover, the theoretical bit-error-rate expressions for additive white Gaussian noise and multipath fading channels are analytically studied and derived. The proposed I-DCSK system is compared with the conventional DCSK and quadrature chaos-shift keying schemes. Finally, to validate accuracy, simulation results are compared with relevant theoretical expressions.
90 citations
TL;DR: A study of potential of brainwaves and their computing for providing higher security in robotic environment and selected and employed the neural network based on learning vector quantization for correct classification.
71 citations
TL;DR: Simulation results show that, by tuning the delay value between the emissions of the two MM types and their respective molecule counts, the proposed pre-equalization method outperforms the aforementioned methods and reduces the bit error rate of the MCvD system significantly.
Abstract: In this letter, a novel pre-equalization method in the context of molecular communication via diffusion (MCvD) is proposed. Our method is based on the emission of two types of messenger molecules (MMs) from the transmitter in order to mitigate the high intersymbol interference (ISI), which critically hinders the performance of any MCvD system. In this approach, the difference between the number of received molecules of each MM type is considered as the actual signal at the receiver side. We model the underlying diffusion channel, and conduct an analysis on the error performance of the proposed method. We compare the proposed method with other modulation and ISI mitigation techniques in the literature, such as concentration shift keying, molecular shift keying, molecular concentration shift keying, and minimum mean squared equalization. Simulation results show that, by tuning the delay value between the emissions of the two MM types and their respective molecule counts, the proposed pre-equalization method outperforms the aforementioned methods and reduces the bit error rate of the MCvD system significantly.
67 citations
TL;DR: A comprehensive analysis of strength-based optimum signal detection model for concentration-encoded molecular communication with spike (i.e., impulsive) transmission based on amplitude-shift keying and on-off keying modulations shows that the receiver thus developed can detect CEMC symbols effectively.
Abstract: In this paper, a comprehensive analysis of strength-based optimum signal detection model has been presented for concentration-encoded molecular communication (CEMC) with spike (i.e., impulsive) transmission based on amplitude-shift keying (ASK) and on-off keying (OOK) modulations. Strength-based optimum signal detection problem in diffusion-based CEMC system has been investigated in detail in the presence of both diffusion noise and intersymbol interference (ISI). The receiver for optimum signal detection has been developed theoretically and explained with both analytical and simulation results of binary signal detection. Results show that the receiver thus developed can detect CEMC symbols effectively; however, the performance is influenced by three main factors, namely, communication range, transmission data rate, and receiver memory. For both ASK and OOK receivers, exact and approximate detection performances have been derived analytically depending on the probabilistic nature of molecular availability and the relationship between mean and variance of signal strengths. Correspondingly, bit error rate (BER) performance of the optimum receiver in a single CEMC link is further evaluated under various scenarios through extensive simulation experiments.
47 citations
08 Jun 2015
TL;DR: It is shown that the signal to interference plus noise ratio (SINR) scales with the number of receive antennas, which confirms the same scaling law found in coherent systems.
Abstract: A non-coherent detection assisted Differential Phase Shift Keying aided large-scale MIMO system is designed in a wireless uplink where multiple single-antenna users are transmitting to the base station's receiver equipped with a very large number of receive antennas We show that the signal to interference plus noise ratio (SINR) scales with the number of receive antennas, which confirms the same scaling law found in coherent systems We propose a range of constellation designs that allow us to separate the users' signals at the receiver by relying only on the knowledge of the average received power per user We analyse the error probability and provide insights into the beneficial selection of the constellation parameters Finally, we provide some numerical results showing that our proposals require a lower number of receive antennas to achieve a given error probability than other non-coherent benchmark schemes available in the literature, while they are not far from an equivalent coherent system relying on realistic channel estimation settings
45 citations
TL;DR: It is shown that, under reasonable degraded conditions on a wiretapper, information theoretically secure communications should be possible in a much wider distance range than a range limit of quantum key distribution, enabling secure optical links between geostationary Earth orbit satellites and ground stations with currently available technologies.
Abstract: Secrecy issues of free-space optical links realizing information theoretically secure communications and high transmission rates are discussed. We numerically study secrecy communication rates of optical wiretap channel based on on–off keying (OOK) modulation under typical conditions met in satellite-ground links. It is shown that, under reasonable degraded conditions on a wiretapper, information theoretically secure communications should be possible in a much wider distance range than a range limit of quantum key distribution, enabling secure optical links between geostationary Earth orbit satellites and ground stations with currently available technologies. We also provide the upper bounds on the decoding error probability and the leaked information to estimate a necessary code length for given required levels of performances. This result ensures that a reasonable length of wiretap channel code for our proposed scheme must exist.
42 citations
TL;DR: In this paper, the statistical orthogonal frequency division multiplexing passive optical network (OFDM-PON) concept with multiband optical network units (ONUs) is experimentally tested with two users and an optical line terminal at 2.5/5 Gb/s total effective capacity with binary phase shift keying (BPSK)/quadrature phase-shift keying modulation.
Abstract: The statistical orthogonal frequency division multiplexing passive optical network (OFDM-PON) concept with multiband optical network units (ONUs) is experimentally tested with two users and an optical line terminal at 2.5/5 Gb/s total effective capacity with binary phase-shift keying (BPSK)/quadrature phase-shift keying (QPSK) modulation. Both downstream and uplink were measured based on intensity modulation and direct detection. The ONUs consisted oflocal nonpreselected wavelength distributed feedback laser sources centrally controlled to reduce overlapping probability. In addition, a radio-frequency mixing stage in the ONUs up/downconverts the user data to/from the OFDM signal, reducing the computational effort. Compared with ONUs processing the whole signal, the multiband approach presents comparable results with almost symmetrical power budgets of around 25 and 20 dB with BPSK and QPSK, respectively, which could increase up to 4.5 dB by allocating a spectral guard interval between the optical carrier and the OFDM data. Furthermore, elastic bandwidth allocation is explored, which is shown to compensate for up to 18 dB differential link loss.
42 citations
TL;DR: An adaptive channel estimation method based on Doppler prediction and time smoothing, whose decision-directed operation allows for reduction in the pilot overhead and an order of magnitude decrease in the bit error rate when the number of carriers is chosen optimally is proposed.
Abstract: In this paper, Alamouti space–frequency block coding, applied over the carriers of an orthogonal frequency-division multiplexing (OFDM) system, is considered for obtaining transmit diversity in an underwater acoustic channel. This technique relies on the assumptions that there is sufficient spatial diversity between the channels of the two transmitters, and that each channel changes slowly over the carriers, thus satisfying the basic Alamouti coherence requirement and allowing simple data detection. We propose an adaptive channel estimation method based on Doppler prediction and time smoothing, whose decision-directed operation allows for reduction in the pilot overhead. System performance is demonstrated using real data transmitted in the 10–15-kHz acoustic band from a vehicle moving at 0.5–2 m/s and received over a shallow-water channel, using quadrature phase-shift keying (QPSK) and a varying number of carriers ranging from 64 to 1024. Results demonstrate an average mean squared error gain of about 2 dB as compared to the single-transmitter case and an order of magnitude decrease in the bit error rate when the number of carriers is chosen optimally.
TL;DR: A reconfigurable dual-channel all-optical logic gate is proposed and experimentally demonstrated using four-wave mixing in a silicon waveguide for polarization encoding signals.
Abstract: A reconfigurable dual-channel all-optical logic gate is proposed and experimentally demonstrated using four-wave mixing in a silicon waveguide for polarization encoding signals Six logic functions, XNOR, AND, NOR, XOR, AB¯, and A¯B are implemented at two different wavelength channels by adjusting the polarization states of two 10 Gb/s non-return-to-zero polarization-shift keying (NRZ-PolSK) signals modulated by 10-bit on–off keying (OOK) sequences The eye diagrams of the logic signals are clearly observed, and the logic functions are well demonstrated as the two incident NRZ-PolSK signals are both modulated by the OOK sequences, which originate from 231−1 pseudo-random binary sequences
TL;DR: In this paper, a construction of amplitude and phase-shift keying (APSK) constellations with equiprobable signaling that achieves the Gaussian capacity as the number of constellation points goes to infinity is given.
Abstract: We consider the Gaussian channel with power constraint $P$ A gap exists between the channel capacity and the highest achievable rate of equiprobable uniformly spaced signal Several approaches enable to overcome this limitation such as constellations with non-uniform probability or constellation shaping In this letter, we focus on constellation shaping We give a construction of amplitude and phase-shift keying (APSK) constellations with equiprobable signaling that achieve the Gaussian capacity as the number of constellation points goes to infinity
TL;DR: A survey and tutorial is provided on the subject of multiple-input-multiple-output (MIMO) multicarrier (MC) systems relying on the space-time shift keying (STSK) concept, followed by the design of STSK systems in the context of MC modulation-based transmissions over dispersive wireless channels.
Abstract: A survey and tutorial is provided on the subject of multiple-input–multiple-output (MIMO) multicarrier (MC) systems relying on the space–time shift keying (STSK) concept. We commence with a brief review of the family of MIMO systems, which is followed by the design of STSK systems in the context of MC modulation-based transmissions over dispersive wireless channels. Specifically, the STSK scheme is amalgamated with orthogonal frequency-division multiplexing, MC code-division multiple access, orthogonal frequency-division multiple access (OFDMA), and single-carrier frequency-division multiple access. We also provide a rudimentary introduction to MC differential STSK employing both conventional differential detection and multiple-symbol differential sphere decoding for the sake of dispensing with channel estimation. We conclude with the design recipes of coherent versus noncoherent MC STSK schemes, complemented by a range of future research ideas.
TL;DR: A 100 Gb/s dual-polarization quadrature phase-shift keying receiver that uses analog domain signal processing is presented that can be drastically reduced in power consumption, size, and cost by processing signals in the analog domain itself.
Abstract: Coherent techniques are expected to be used to meet the demand for higher data rates in short-reach optical links in the near future. Digital coherent receivers used for long haul applications are not suitable for short-reach links because of excessive power dissipation, size, and cost. The power consumption, size, and cost of the receiver can be drastically reduced by processing signals in the analog domain itself. A 100 Gb/s dual-polarization quadrature phase-shift keying receiver that uses analog domain signal processing is presented. The receiver, designed in 130-nm BiCMOS technology, consumes 3.5 W of power. Simulations show bit error rates of less than $10^{-3}$ in the presence of dispersion up to 160 ps/nm, laser linewidths of up to 200 kHz, and a frequency offset of 100 MHz between the transmitter and the receiver lasers.
TL;DR: A model analytical description of optical wireless communication systems operation performance efficiency evaluation in the presence of different fog density levels and noise is constructed and used for quantitative determination of the maximum range between transmitter and receiver depending on the signal transmission quality.
Abstract: The free space optical communication technology tries to fulfill rising need for high bandwidth transmission capability link along with security and ease in installation. The free space optics uses beam of light to provide optical connection that can send and receive video, voice, and data information. In this paper a model analytical description of optical wireless communication systems operation performance efficiency evaluation in the presence of different fog density levels and noise is constructed. It is used for quantitative determination of the maximum range between transmitter and receiver depending on the signal transmission quality. Link margin, signal transmission, signal quality, received signal power, particle size distribution, optical depth, transmission data rate, signal time delay spread, signal noise and signal attenuation are deeply studied over wide range of the affecting parameters. Signal time delay spread and signal to noise ratio are deeply studied with using on-off keying modulation technique and are compared with their results with using binary phase shift keying in Li et al. (IEEE Trans Commun 55:1598---1606, 2007).
TL;DR: In this article, the bit-error rate performance of different subcarrier phase-shift keying systems with carrier phase errors (CPE) in lognormal turbulence channels where the CPE is modeled as a Tikhonov random variable is analyzed.
Abstract: We study the bit-error rate performance of different subcarrier phase-shift keying systems with carrier phase errors (CPE) in lognormal turbulence channels where the CPE is modeled as a Tikhonov random variable. The CPE induced asymptotic noise reference losses for the studied systems are quantified analytically by introducing the lognormal-Nakagami fading as an auxiliary channel model. The auxiliary channel method used in this study can be potentially applied to other performance analysis problems involving the lognormal channels.
TL;DR: A digital channel model based on the on–off keying and time slot scheme is established, which establishes a capacity expression derived with consideration of the effects of the channel memory and ligand‐receptor binding mechanisms.
Abstract: Diffusion-based communication is one of the most dominating forms in the micrometer and nanoscale communications. Generally, information is coded in molecules that are released by a transmitter nanomachine, propagated via a diffusion-based channel, and then received by a receiving nanomachine called receiver. The receiver considered in this paper is equipped with multiple ligand receptors. The molecular communication system in this paper is single hop and SISO. Namely, there is only a channel connecting a pair of transmitter and receiver. While most literature considers either the channel or the receptors, this paper proposes a channel model that takes into account both the diffusion-based channel and the ligand-based receiver. The channel capacity under such model is analyzed, which studies the impact of different parameters at both channel and the receiver on the performance of the molecular communication system. We establish a digital channel model based on the on-off keying and time slot scheme. A capacity expression is derived with consideration of the effects of the channel memory and ligand-receptor binding mechanisms. The numerical results show that the overall channel capacity is restricted by the physical parameters of diffusion channel and ligand receptors. Copyright © 2014 John Wiley & Sons, Ltd.
TL;DR: Two novel near-ML but low-complexity detection schemes for SM-MIMO systems, which use M-ary amplitude and phase-shift keying (APSK) digital modulation, are proposed, which confirm that the proposed detection schemes provide bit error probability performance close to that of ML demodulation but with lower demodulated complexity.
Abstract: Spatial modulation (SM) is a promising multiple-input–multiple-output (MIMO) transmission technology, which exploits the indexes of the transmit antennas for encoding information into the spatial dimension and, thus, for increasing the transmission rate. Optimal demodulation is realized by using a maximum-likelihood (ML) detector, which jointly estimates the information bits encoded into the transmit antenna indexes and into the transmitted symbol. If a large number of transmit antennas and/or a large modulation size are used; however, the computational complexity of ML demodulation may not be affordable for some applications. Against this background, we propose two novel near-ML but low-complexity detection schemes for SM-MIMO systems, which use $\boldsymbol{M}$ -ary amplitude and phase-shift keying (APSK) digital modulation. The proposed algorithms exploit specific features of the $\boldsymbol{M}$ -ary APSK constellation diagram, in order to avoid searching among all constellation points. It is shown, in particular, that the complexity of the proposed detection schemes is independent of the constellation size and that it only depends on the number of rings that constitute the APSK constellation. Simulation results are also provided, which confirm that the proposed detection schemes provide bit error probability performance close to that of ML demodulation but with lower demodulation complexity.
TL;DR: A new all-digital impulse radio ultrawideband pulse generator in a 65-nm CMOS technology for a wireless body area network is presented and delay-based binary phase-shift keying is used to achieve an efficient spectral line characteristic.
Abstract: A new all-digital impulse radio ultrawideband pulse generator in a 65-nm CMOS technology for a wireless body area network is presented. The system architecture is a delay-based pulse generator that is designed using only logic gates to minimize the power consumption. The system uses a frequency range of 3.1–4.8 GHz and 3 channels with a 500-MHz bandwidth. The maximum data rate of this system is 100 Mb/s with pulse positioned modulation and 200 Mb/s with on–off keying. Delay-based binary phase-shift keying is used to achieve an efficient spectral line characteristic. The total power consumption of the pulse generator is 30 pJ/pulse at a 1.2-V supply voltage without a static bias current.
TL;DR: This study designs and analyses a new phase-coded spread-spectrum communication system where both phase- coded carrier and spreading factor are varied based on a chaotic behaviour in the communication process to reduce the probability of interception of the considered system.
Abstract: This study designs and analyses a new phase-coded spread-spectrum communication system where both phase-coded carrier and spreading factor are varied based on a chaotic behaviour in the communication process. This design aims to reduce the probability of interception of the considered system. Discrete values generated by a chaotic map are exploited to create a non-return-to-zero (NRZ)-chaos sequence and simultaneously make bit duration variable. The NRZ-chaos sequence is then modulated by binary phase-shift keying technique to produce the phased-coded carrier. Owing to chip duration being constant, the variation of bit duration also leads to the variation of spreading factor. Spectrum spreading in the transmitter is performed by multiplying directly the variable-duration bits with the phase-coded carrier. A coherent receiver relying on a direct correlator is used for recovering the data. Design of the transmitter and receiver as well as analysis of bit error probability for the proposed system in cases of single-user and multi-user under additive white Gaussian noise channel is presented. Simulation results are shown to confirm the operation of the designed structures and the obtained analytical performance.
Posted Content•
TL;DR: This paper investigates the indoor positioning accuracy of optical based OFDM techniques used in VLC systems and demonstrates that OFDM positioning system outperforms its conventional counterpart.
Abstract: Visible Light Communication (VLC) technology using light emitting diodes (LEDs) has been gaining increasing attention in recent years as it is appealing for a wide range of applications such as indoor positioning. Orthogonal frequency division multiplexing (OFDM) has been applied to indoor wireless optical communications in order to mitigate the effect of multipath distortion of the optical channel as well as increasing data rate. In this paper, we investigate the indoor positioning accuracy of optical based OFDM techniques used in VLC systems. A positioning algorithm based on power attenuation is used to estimate the receiver coordinates. We further calculate the positioning errors in all the locations of a room and compare them with those of single carrier modulation scheme, i.e., on-off keying (OOK) modulation. We demonstrate that OFDM positioning system outperforms its conventional counterpart.
TL;DR: This paper derives the exact end-to-end symbol error probability (SEP) for SR–RD correlated channel scenario and provides the asymptotic expressions for SEP and outage probability by removing the infinite-series terms to investigate the diversity order.
Abstract: A cooperative diversity system improves the communication reliability and throughput in a multipath fading environment with the help of relay nodes. We consider a cooperative diversity system with a source (S), a decode-and-forward relay (R), and a selection-combining-enabled destination (D). In this paper, we derive the exact end-to-end symbol error probability (SEP) for $M$ -ary phase-shift keying (MPSK) signaling using a paired error approach and differential binary phase-shift keying (DBPSK) signaling over correlated, nonidentical, slow, and flat Nakagami- $m$ fading channels by assuming the correlation between SD–RD, SR–SD, and SR–RD fading channels. In addition, we perform the exact outage probability analysis for the same scenario. Furthermore, we provide the asymptotic expressions for SEP and outage probability by removing the infinite-series terms to investigate the diversity order. In a nutshell, the numerical results reveal that the SR–RD correlated channel scenario outperforms the uncorrelated channel scenario in terms of SEP. In addition, SEP performance degradation is observed in the case of other correlated channel scenarios compared with the uncorrelated channel scenario. Moreover, marginal performance improvement in outage probability is observed in the low-signal-to-noise-ratio (SNR) regime of the SR–RD correlated channel scenario compared with the uncorrelated channel scenario. Finally, Monte Carlo simulations are performed to validate the theoretical results.
TL;DR: A new approach for data modulation in 2-D barcodes is introduced, and its performance is evaluated in comparison to other standard methods of barcode modulation.
Abstract: The concept of 2-D barcodes is of great relevance for use in wireless data transmission between handheld electronic devices. In a typical setup, any file on a cell phone, for example, can be transferred to a second cell phone through a series of images on the LCD which are then captured and decoded through the camera of the second cell phone. In this study, a new approach for data modulation in 2-D barcodes is introduced, and its performance is evaluated in comparison to other standard methods of barcode modulation. In this new approach, orthogonal frequency-division multiplexing (OFDM) modulation is used together with differential phase shift keying (DPSK) over adjacent frequency domain elements. A specific aim of this study is to establish a system that is proven tolerant to camera movements, picture blur, and light leakage within neighboring pixels of an LCD.
TL;DR: A novel error control scheme using Fountain codes is proposed in on–off keying (OOK) based visible light communications (VLC) systems, employing scrambling techniques and complementing symbols to support arbitrary dimming target values.
TL;DR: An analytical approximation for the maximum PPM transmission rate is derived, quantifying the effects of photon statistics on the communication efficiency in terms of the g((2)) second-order intensity correlation function of the light source.
Abstract: We analyze the performance of on-off keying (OOK) and its restricted version pulse position modulation (PPM) over a lossy narrowband optical channel under the constraint of a low average photon number, when direct detection is used at the output. An analytical approximation for the maximum PPM transmission rate is derived, quantifying the effects of photon statistics on the communication efficiency in terms of the g(2) second-order intensity correlation function of the light source. Enhancement attainable through the use of sub-Poissonian light is discussed.
01 Sep 2015
TL;DR: This paper shows that signal injection attack is feasible in practice and leads to a strong correlation between the injected signal and channel measurements at legitimate users for existing key generation methods, and proposes a countermeasure, PHY-UIR (PHYsical layer key agreement with User Introduced Randomness).
Abstract: Physical layer key agreement techniques derive a symmetric cryptographic key from the wireless fading channel between two wireless devices by exploiting channel randomness and reciprocity. Existing works mainly focus on the security analysis and protocol design of the techniques under passive attacks. The study on physical layer key agreement techniques under active attacks is largely open. In this paper, we present a new form of high threatening active attack, named signal injection attack. By injecting the similar signals to both keying devices, the attacker aims at manipulating the channel measurements and compromising a portion of the key. We further propose a countermeasure to the signal injection attack, PHY-UIR (PHYsical layer key agreement with User Introduced Randomness). In PHY-UIR, both keying devices independently introduce randomness into the channel probing frames, and compose common random series by combining the randomness in the fading channel and the ones introduced by users together. With this solution, the composed series and injected signals become uncorrelated. Thus, the final key will automatically exclude the contaminated portion related to injected signal while persisting the other portion related to random fading channel. Moreover, the contaminated composed series at two keying devices become decorrelated, which help detect the attack. We analyze the security strength of PHY-UIR and conduct extensive simulations to evaluate it Both theoretical analysis and simulations demonstrate the effectiveness of PHY-UIR. We also perform proof-of-concept experiments by using software defined radios in a real-world environment. We show that signal injection attack is feasible in practice and leads to a strong correlation (0.75) between the injected signal and channel measurements at legitimate users for existing key generation methods. PHY-UIR is immune to the signal injection attack and results in low correlation (0.15) between the injected signal and the composed random signals at legitimate users.
06 Feb 2015
TL;DR: Evaluation of SNR in terms of constant bit error rate is performed on AWGN, Rayleigh and Rician fading channels to show whether Rician is showing better performance as compared to AWGN and Rayleigh.
Abstract: With the growing demand in modern communication, it has become necessary to give better and efficient service to users by using better technique. Technique such as Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK), Differential Phase shift Keying (DPSK) and Quadrature Amplitude Modulation (QAM) are very important parts of the implementation of modern communications systems in which DPSK is the simplest and most robust of all techniques. In this paper, evaluation of SNR in terms of constant bit error rate is performed on AWGN, Rayleigh and Rician fading channels. Among these channels, Rician is showing better performance as compared to AWGN and Rayleigh.
TL;DR: Numerical results show that, for OOK signal format, the general GLRT outperforms the sum-counting test at the cost of higher computational complexity, but for PPM signal format both detection schemes perform virtually the same.
Abstract: Due to the unlicensed spectrum nature of the optical wireless communication, for a transceiver pair, the receiver needs to periodically sense the communication media, aiming to better schedule its transmission. Considering that the data symbols or channel parameters are unknown, we adopt a generalized likelihood ratio test (GLRT), which is known to be optimal with unknown parameters based on finite samples. This paper proposes two detection rules on whether there are optical signals falling into the receiver field of view within certain time slot(s), based on the sum number of received photons over all sensing slots, as well as the number of received photons in each slot. The formal one is named the sum-counting test and the latter one is named as the general GLRT. We design the corresponding detection schemes for both on–off keying (OOK) and pulse-position modulation (PPM) signal formats. We also provide asymptotic results on the miss detection probability. Numerical results show that, for OOK signal format, the general GLRT outperforms the sum-counting test at the cost of higher computational complexity, but for PPM signal format both detection schemes perform virtually the same.
TL;DR: This work introduces the multi-dimensional permutation-modulation format in coherent optical communication systems and analyzes its performance, focusing on the power efficiency and the spectral efficiency.
Abstract: We introduce the multi-dimensional permutation-modulation format in coherent optical communication systems and analyze its performance, focusing on the power efficiency and the spectral efficiency. In the case of four-dimensional (4D) modulation, the polarization-switched quadrature phase-shift keying (PS-QPSK) modulation format and the polarization quadrature-amplitude modulation (POL-QAM) format can be classified into the permutation modulation format. Other than these well-known modulation formats, we find novel modulation formats trading-off between the power efficiency and the spectral efficiency. With the increase in the dimension, the spectral efficiency can more closely approach the channel capacity predicted from the Shannon’s theory. We verify these theoretical characteristics through computer simulations of the symbol-error rate (SER) and bit-error rate (BER) performances. For example, the newly-found eight-dimensional (8D) permutation-modulation format can improve the spectral efficiency up to 2.75 bit/s/Hz/pol/channel, while the power penalty against QPSK is about 1 dB at BER=10−3.