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This paper presents an energy-efficient design of optical wireless communication (OWC) system for the indoor Internet of Things (IoT) with the assistance of machine learning (ML). A central coordinator (CC) has been proposed to interrogate the IoT devices and control the uplink formations with the prediction of transmission quality using ML classifiers. The passive reflective reflectors (PRF) are utilized in the IoT devices, which replaced the power-consuming active transmitters, formulate the zero-power consuming transmission links. The communication performance of the passive link establishments from the IoT devices have been investigated in terms of quality factor (Q-factor), bit error rate (BER), and signal-to-noise ratio (SNR) under different optical wireless channel conditions and link lengths. The ML classifiers have been evaluated on the prediction of transmission quality, and the results suggested the Euclidean K-nearest neighbor (KNN) with ten number of neighbors for the implementation. The IoT devices located within 1.2 m from the CC require a transmission power of 0.5 mW for links carrying 10 Gbps data, which increases the energy efficiency to 20 Gbps/mW with transmission energy consumption of 0.05 pJ/bit. This significant improvement in energy efficiency and passive communication ensures reliable, and green IoT links suitable for data-intensive indoor applications. [ABSTRACT FROM AUTHOR]

This study enhances infrared communication security in nuclear power plants' secondary systems, addressing the risk of mechanical and cyber failures. A novel random address generator, employing an innovative S-box, was developed to secure IoT sensor data transmissions to gateway nodes, mitigating eavesdropping, interference, and replay attacks. We introduced a structured IR communication protocol, generating unique, encrypted addresses to prevent unauthorized access. Key-dependent S-boxes, based on a compound chaotic map system, significantly improved encryption, increasing data transmission randomness and uniqueness. Entropy analysis and reduced duplicated addresses confirmed the effectiveness of our method, with the Hash-CCM algorithm showing the highest entropy and fewest duplicates. Integrating advanced cryptographic techniques into IR systems significantly enhances nuclear power plants' security, contributing to the protection of critical infrastructure from cyber threats and ensuring operational integrity. [ABSTRACT FROM AUTHOR]

The Optical Wireless Communication (OWC) offers the high capacity of optical fiber communication with the flexibility of wireless communication. Since it works in the optical region of the ElectroMagnetic (EM) spectrum, it guarantees safety and security which are critical in radio and microwave frequency communication. The principal objective of this paper is to analyze the indoor OWC systems on these guaranteed features, and safety and security are jointly denoted by the term green. The high obstacle impermeability of optical signals and their directivity strengthen the security of indoor OWC data transmission. The confidentiality and authenticity of optical wireless data can also be preserved with the Quantum Key Distribution (QKD). This paper provides a technological overview and a review of literature about the OWC system that helps to identify the challenges in the path of a ubiquitous deployment of green wireless communication systems. Significant advancements in the sources and detectors are discussed together with the coding, modulation and multiplexing techniques for making highly robust OWC links. The ubiquitous deployment of green OWC necessitates the development of optical transmitters and receivers, performance enhancement techniques, incorporation of uplink and energy harvesting abilities, and safety and security enhancement techniques. Hence, a special emphasis is placed on these aspects and their challenges towards the green implementation. Furthermore, the paper explores some significant indoor applications based on the OWC that have great impacts on the Next Generation Networks (NGN) and the Internet of Things (IoT).

Based on data from the Indonesian Traffic Corps by September 2019, the number of car accidents was dominated by rear-hit crashes with 6,966 accidents. Most of these accidents occurred during car convoys. It needs a car-to-car communication to increase driver awareness. One of the technologies that can be applied is Visible Light Communication (VLC) and infrared communication. The transmitted data are the vehicle speed data, throttle position, and brake stepping indicator. The data are obtained by reading the Engine Control Unit (ECU) in the car. The data are packaged from the three data and sent to other cars at day and night using VLC and infrared communication. The experimental results show that in a communication system that uses VLC, data can be exchanged between cars during the day up to 2 meters and at night up to 11 meters. Otherwise, in infrared communication, vehicles can communicate during the day up to 2 meters and at night up to 0.7 meter. The test was also carried out with some conditions such as rain, smoke, passers, and other vehicle lights.

In recent years, application of multiple robot system for a large scale system, such as a smart factory, is expected. A system consisting of heterogeneous robots can select the function by switching a combination of the robots according to a purpose. Therefore, the system is more versatile than a single robot on which multiple functions are installed. When the system is controlled by distributed management, it is an essential technique that the robots communicate with each other for mutual understanding to achieve complex task. We have developed spatially seamless local communication system in order to exchange information between the robots without convergences. This system ensures spatially seamless communicable area towards robot's surroundings by rotating a transmitter and a receiver. However, a bit rate of communication using the system is insufficient. Although the system has redundant frame structure to detect interference between signals from different transmitters, it causes decrease of the bit rate. In this paper, we aim to improve the bit rate by reducing frame length of transmission pulse while retaining the interference detection function. [ABSTRACT FROM AUTHOR]

This paper studies the capacity of a general multiple-input multiple-output (MIMO) free-space optical intensity channel under a per-input-antenna peak-power constraint and a total average-power constraint over all input antennas. The focus is on the scenario with more transmit than receive antennas. In this scenario, different input vectors can yield identical distributions at the output, when they result in the same image vector under multiplication by the channel matrix. We first determine the most energy-efficient input vectors that attain each of these image vectors. Based on this, we derive an equivalent capacity expression in terms of the image vector, and establish new lower and upper bounds on the capacity of this channel. The bounds match when the signal-to-noise ratio (SNR) tends to infinity, establishing the high-SNR asymptotic capacity. We also characterize the low-SNR slope of the capacity of this channel. [ABSTRACT FROM AUTHOR]

As the number of elderly drivers increases, traffic accidents from the elderly also increase. In particular, the emergency situation of the elderly driver is not transmitted to the following vehicle during cloudy days and night highway accidents, so it is extended to the second and third accidents, leaving serious aftereffects. Therefore, there is an urgent need to establish an economic and effective inter-vehicle emergency communication system between the accident vehicle of the elderly and the following vehicles. In this paper, we have proposed a policy and method that can take advantage of the special emergency light pattern of an elderly driver in an emergency and transmit it to the following vehicles, thereby providing secondary accident prevention and emergency relief. Furthermore, by introducing an infrared emergency communication system between vehicles using red brake lights and implementing it as a prototype of RC-Car, we have checked the feasibility of the system. [ABSTRACT FROM AUTHOR]

Infrared (IR) communication is one of the wireless communication methods mainly used to manipulate consumer electronics devices. Traditional IR devices support only simple operations such as changing TV channels. These days, consumer electronic devices such as smart TV are connected to the internet with the introduction of IoT. Thus, the user’s sensitive information such as credit card number and/or personal information could be entered with the IR remote. This situation raises a new problem. Since TV and the set-top box are visual media, these devices can be used to control and/or monitor other IoT devices at home. Therefore, personal information can be exposed to eavesdroppers. In this paper, we experimented with the IR devices’ reception sensitivity using remotes. These experiments were performed to measure the IR reception sensitivity in terms of distance and position between the device and the remote. According to our experiments, the transmission distance of the IR remote signal is more than 20 m. The experiments also revealed that curtains do not block infrared rays. Consequently, eavesdropping is possible to steal the user’s sensitive information. This paper proposes a simple, practical, and cost-effective countermeasure against eavesdropping, which does not impose any burden on users. Basically, encryption is used to prevent the eavesdropping. The encryption key is created by recycling a timer inside the microcontroller typically integrated in a remote. The key is regenerated whenever the power button on a remote is pressed, providing the limited lifecycle of the key. The evaluation indicates that the XOR-based encryption is practical and effective in terms of the processing time and cost.

To evaluate and improve the value of a service, it is important to measure not only the outcomes, but also the process of the service. Value co-creation (VCC) is not limited to outcomes, especially in interpersonal services based on interactions between actors. In this paper, a sensing framework for a VCC process in retail stores is proposed by improving an environment recognition based indoor positioning system with high positioning performance in a metal shelf environment. The conventional indoor positioning systems use radio waves; therefore, errors are caused by reflection, absorption, and interference from metal shelves. An improvement in positioning performance was achieved in the proposed method by using an IR (infrared) slit and IR light, which avoids such errors. The system was designed to recognize many and unspecified people based on the environment recognition method that the receivers had installed, in the service environment. In addition, sensor networking was also conducted by adding a function to transmit payload and identification simultaneously to the beacons that were attached to positioning objects. The effectiveness of the proposed method was verified by installing it not only in an experimental environment with ideal conditions, but posteriorly, the system was tested in real conditions, in a retail store. In our experimental setup, in a comparison with equal element numbers, positioning identification was possible within an error of 96.2 mm in a static environment in contrast to the radio wave based method where an average positioning error of approximately 648 mm was measured using the radio wave based method (Bluetooth low-energy fingerprinting technique). Moreover, when multiple beacons were used simultaneously in our system within the measurement range of one receiver, the appropriate setting of the pulse interval and jitter rate was implemented by simulation. Additionally, it was confirmed that, in a real scenario, it is possible to measure the changes in movement and positional relationships between people. This result shows the feasibility of measuring and evaluating the VCC process in retail stores, although it was difficult to measure the interaction between actors.

A method to locate the position of the target vehicle with the aid of infrared signal-direction discrimination for short-range vehicle-to-vehicle communications is proposed in this paper. With the use of two one-dimensional (1-D) signal-direction discriminators mounted on a vehicle with a lateral separation between them to measure the coming directions of the signal emitted from another target vehicle, the position of the target vehicle relative to this detecting vehicle can be located by triangulation. The aforementioned 1-D signal-direction discriminator is composed of two planar receiving modules forming a specific geometric structure, which leads to different responsivities of these individual receiving modules for a signal incident from a definite direction. The coming direction of the signal is determined by comparing the signal strengths received by these individual receiving modules. With a proposed hardware and software implementation, the position of the target vehicle can be accurately determined within a longitudinal range of 50 m. Owing to the restriction of the width of the vehicle, the separation of the signal-direction discriminators mounted on the vehicle cannot exceed 1.8 m. This leads to the consequence that in the remote region any small inaccuracy of the measured signal directions may cause very large position error. However, our measured results reveal a specific characteristic of the distribution of the measured positions for the target vehicle at a definite location. This allows us to design deliberate statistical algorithms to accurately extract the position of the target vehicle in the remote region. Using the simplest statistical algorithm, we are able to locate the position of the target vehicle with acceptable accuracy within a longitudinal range of 80 m. In this paper, we show the feasibility and applicability of this method. Furthermore, improvement is foreseeable with more deliberate design of hardware and software. [ABSTRACT FROM AUTHOR]

This paper derives upper and lower bounds on the capacity of the multiple-input single-output free-space optical intensity channel with signal-independent additive Gaussian noise subject to both an average-intensity and a peak-intensity constraint. In the limit where the signal-to-noise ratio (SNR) tends to infinity, the asymptotic capacity is specified, while in the limit where the SNR tends to zero, the exact slope of the capacity is given. [ABSTRACT FROM AUTHOR]

In this paper, we propose a reliable method to determine the coming direction of an infrared signal, where the direction of the signal sent by the vehicle relative to the receiver is determined by amplitude comparison. We utilize a simple symmetric structure comprising four identical planar receiving modules, each with a specific tilt angle relative to the receiving plane, to construct the receiver. The coming direction of the signal is extracted by comparing the signal strengths received by these four receiving modules. With the aid of a simple geometric relation, the trajectory of a vehicle is tracked, i.e., its positions are located, from the coming direction of the signal originated from this vehicle when it travels through the communication area of the system. For several vehicles simultaneously appearing in the communication area, the vehicles can be distinguished in the frequency domain from different frequencies sent by different vehicles. Our signal-direction discriminator proposed in this paper is able to locate the position of the vehicle in a communication area of 6 m in width and 20 m in length. In the lateral direction, this area sufficiently covers a typical traffic lane; in the longitudinal direction, it meets the general requirements of shorter than 20 m for common short-range vehicle-to-infrastructure communication systems, such as electronic-toll-collection applications. [ABSTRACT FROM PUBLISHER]

According to our measurements, the radiation pattern of many low-cost commercial light-emitting diodes (LEDs) is not smooth. Some LEDs even have serious irregularities that affect the performance of infrared communication systems. For systems where a definite communication area is required, such as electronic-toll-collection (ETC) applications, this problem is particularly serious. In this paper, we first present our measured results for the radiation pattern of several typical low-cost commercial LEDs, showing that almost all of them are irregular to some extent. We then use the most acceptable model with a suitable half-intensity angle to construct the emitter of an ETC system. The design was calculated with the aid of an optimization algorithm to determine the mounting angle for each LED such that the system has an extended communication area in the longitudinal direction, i.e., in the vehicle traveling direction, and can withstand high signal attenuation. For a typical LED with half-intensity angle \Phi1/2 = 13^{\circ}, a very simple two-group structure for the emitter is obtained, and the analysis results are verified by experimental measurements. [ABSTRACT FROM PUBLISHER]

Based on our previous works in the design of an infrared emitter for electronic-toll-collection (ETC) applications, we use the unidirectional \cosine^n functions to approximate the irregular radiation pattern for typical infrared low-cost commercial light-emitting diodes (LEDs) with a half-intensity angle \Phi1/2 = 10^{\circ}. With the aid of this approximation, the main characteristics of the performance of an infrared ETC system utilizing this type of LED as the emitter can be investigated based on the received signal strength of the system. For on–off keying, a simple model connecting the received signal strength and the bit error rate (BER) of the system is further established. From the calculated or the measured received signal strength of the system, it is not difficult to estimate the system performance in terms of the BER by this simple model. Roughly speaking, for a typical setting of the circuit parameters and a typical uplink and downlink data-transmission protocol, the data transmission can be very successful in terms of a very low BER if the received signal strength is 1.3 times stronger than the signal strength received at the communication boundary. The emitter presented in this paper is able to produce a relatively extended communication area in the vehicle-traveling direction, resulting in longer communication time interval for the data transmission between the onboard unit (OBU) and the roadside unit (RSU) than conventional emitters. Furthermore, the design presented in this paper is validated by experimental measurement to demonstrate its effectiveness. [ABSTRACT FROM PUBLISHER]

Upper and lower bounds are derived on the capacity of the free-space optical intensity channel. This channel has a nonnegative input (representing the transmitted optical intensity), which is corrupted by additive white Gaussian noise. To preserve the battery and for safety reasons, the input is constrained in both its average and its peak power. For a fixed ratio of the allowed average power to the allowed peak power, the difference between the upper and the lower bound tends to zero as the average power tends to infinity and their ratio tends to one as the average power tends to zero. When only an average power constraint is imposed on the input, the difference between the bounds tends to zero as the allowed average power tends to infinity, and their ratio tends to a constant at the allowed average power tends to zero. [ABSTRACT FROM AUTHOR]

This paper proposes a very simple method for enhancing the performance of infrared electronic-toll-collection systems. Using two typical low-cost commercial LEDs with different half-intensity angles Phi1/2 = 22^{circ} and 10^circ, the radiation pattern of the emitting module of an infrared short-range communication system for electronic-toll-collection applications is designed. This enables us to construct a system that has an extended communication region and can withstand high signal attenuation. When the module is fabricated with a proper combination of the numbers of these two different LEDs, together with a suitable mounting angle of each LED, an effective radiation pattern is obtained. The mounting angle of each LED is found with the aid of an optimization algorithm. The performances of three different designs are compared in terms of signal strength, communication length, and 2-D communication region. The results show that a module consisting of ten LEDs divided into three groups, with each group having a proper mounting angle and containing an appropriate number of LEDs, can have much better performance than conventional single-group unidirectional designs. The influence of the defect of the radiation pattern, which may happen on many LEDs, on system performance is also discussed. The results of the analysis are confirmed by experimental measurements. [ABSTRACT FROM PUBLISHER]

With the aid of a simple relation, which is analogous to the radar equation, the uplink signal strength received by the receiving module of a roadside unit (RSU) and emitted from the radiation module of an onboard unit (OBU) can be described. Setting the scale of this relation arbitrarily and determining the signal strength threshold from experimental measurements, and combined with the simulation of the radiation and the receiving pattern by cosinen function, the relative signal strength emitted from the OBU and received by the RSU can be calculated successfully. From this computed relative signal strength and the threshold, the influence of the RSU and OBU mounting parameters, such as the mounting angles and mounting height, on the available communication region is analyzed. The effect of windshield fading is also considered. With the help of the analysis results, an optimum RSU and OBU mounting configuration can be easily obtained. This method can be used conveniently and successfully for very short wavelengths. This includes visible light, infrared, and even submillimeter-wave ranges. For millimeter-wave and microwave systems, this method can, in some cases, also provide a rudimentary estimation [ABSTRACT FROM PUBLISHER]

We determine upper and lower bounds on the channel capacity of power- and bandwidth-constrains optical intensity channels corrupted by white Gaussian noise. These bounds are shown to converge asymptotically at high optical signal-to-noise ratios (SNRs). Unlike previous investigations on low-intensity Poisson photon counting channels, such as some fiber optic links, this channel model is realistic for indoor free space optical channels corrupted by intense ambient light. An upper bound on the capacity is found through a sphere-packing argument while a lower bound is computed through the maxentropic source distribution. The role of bandwidth is expressed by way of the effective dimension of the set of signals and, together with an average optical power constraint, is used to determine bounds on the spectral efficiency of time-disjoint optical intensity signaling schemes. The bounds show that, at high optical SNRs, pulse sets based on raised-quadrature amplitude modulation (QAM) and prolate spheroidal wave functions have larger achievable maximum spectral efficiencies than traditional rectangular pulse basis sets. This result can be considered as an extension of previous work on photon counting channels which closely model low optical intensity channels with rectangular pulse shapes. [ABSTRACT FROM AUTHOR]

Indoor infrared communication systems is one of the possible ways of offering data rates in excess of 100 Mbit/s without the need for wiring. Multiple users can share an infrared channel by code division-multiple access (CDMA) techniques. However, the CDMA system performance is limited by both background noise and co-channel interference. In this paper we study the use of angle diversity for mitigating the effects of the noise and interference. The system considered uses on-off shift keying modulation with multibeam transmitters and imaging receivers. The overall system performance for different diversity combining techniques is evaluated and compared to a system without diversity. Numerical results for a 2-user CDMA system indicate that signal to noise and interference ratio (SNIR) improvement (over systems with no diversity) of 5 dB is obtained for at least 50% of an ensemble of 10000 sample evaluations. The generalized selection combining (GSC)—a new diversity technique yet to be implemented for infrared systems—offers the best performance even with its reduced complexity. [ABSTRACT FROM AUTHOR]

Infrared (IR) communication is one of the wireless communication methods mainly used to manipulate consumer electronics devices. Traditional IR devices support only simple operations such as changing TV channels. These days, consumer electronic devices such as smart TV are connected to the internet with the introduction of IoT. Thus, the user's sensitive information such as credit card number and/or personal information could be entered with the IR remote. This situation raises a new problem. Since TV and the set-top box are visual media, these devices can be used to control and/or monitor other IoT devices at home. Therefore, personal information can be exposed to eavesdroppers. In this paper, we experimented with the IR devices' reception sensitivity using remotes. These experiments were performed to measure the IR reception sensitivity in terms of distance and position between the device and the remote. According to our experiments, the transmission distance of the IR remote signal is more than 20 m. The experiments also revealed that curtains do not block infrared rays. Consequently, eavesdropping is possible to steal the user's sensitive information. This paper proposes a simple, practical, and cost-effective countermeasure against eavesdropping, which does not impose any burden on users. Basically, encryption is used to prevent the eavesdropping. The encryption key is created by recycling a timer inside the microcontroller typically integrated in a remote. The key is regenerated whenever the power button on a remote is pressed, providing the limited lifecycle of the key. The evaluation indicates that the XOR-based encryption is practical and effective in terms of the processing time and cost. [ABSTRACT FROM AUTHOR]

We have been exploring the use of handheld devices for computer-supported collaborative work. We believe there is a particularly interesting synergy between handheld devices and awareness. We describe several prototypes. One provides email awareness via pagers. Another integrates that email awareness system with an existing colleague awareness system. Two other prototypes are used for note-passing among colleagues when adversaries are present. Note-passing requires both awareness of the receiving party's identity and taking measures against the adversary's awareness of the note-passing activity. [ABSTRACT FROM AUTHOR]

To evaluate and improve the value of a service, it is important to measure not only the outcomes, but also the process of the service. Value co-creation (VCC) is not limited to outcomes, especially in interpersonal services based on interactions between actors. In this paper, a sensing framework for a VCC process in retail stores is proposed by improving an environment recognition based indoor positioning system with high positioning performance in a metal shelf environment. The conventional indoor positioning systems use radio waves; therefore, errors are caused by reflection, absorption, and interference from metal shelves. An improvement in positioning performance was achieved in the proposed method by using an IR (infrared) slit and IR light, which avoids such errors. The system was designed to recognize many and unspecified people based on the environment recognition method that the receivers had installed, in the service environment. In addition, sensor networking was also conducted by adding a function to transmit payload and identification simultaneously to the beacons that were attached to positioning objects. The effectiveness of the proposed method was verified by installing it not only in an experimental environment with ideal conditions, but posteriorly, the system was tested in real conditions, in a retail store. In our experimental setup, in a comparison with equal element numbers, positioning identification was possible within an error of 96.2 mm in a static environment in contrast to the radio wave based method where an average positioning error of approximately 648 mm was measured using the radio wave based method (Bluetooth low-energy fingerprinting technique). Moreover, when multiple beacons were used simultaneously in our system within the measurement range of one receiver, the appropriate setting of the pulse interval and jitter rate was implemented by simulation. Additionally, it was confirmed that, in a real scenario, it is possible to measure the changes in movement and positional relationships between people. This result shows the feasibility of measuring and evaluating the VCC process in retail stores, although it was difficult to measure the interaction between actors. [ABSTRACT FROM AUTHOR]