Bidirectional Communication Scheme Research Articles

An augmented diffusion algorithm with bidirectional communication for a distributed active noise control system.

Recent studies on diffusion adaptation for distributed active noise control (DANC) systems have attracted significant research interest due to their balance between computational burden and stability compared to conventional centralized and decentralized adaptation schemes. The conventional multitask diffusion FxLMS algorithm assumes that the converged solutions of all control filters are consistent to each other, which is unrealistic in practice hence results in inferior performance in noise reduction. An augmented diffusion FxLMS algorithm has been proposed to overcome this problem, which adopts a neighborhood-wide adaptation and node-based combination approach to mitigate the bias in the converged solution of the multitask diffusion algorithms. However, the improvement comes at the expense of a higher computational burden and communication cost. All existing DANC systems, including the multitask and augmented diffusion algorithms, assume one-way communication between nodes. By contrast, this paper proposes a bidirectional communication scheme for the augmented diffusion algorithm to further reduce the memory requirement, computational burden, and communication cost. Simulation results in the free field and with measured room impulse responses both demonstrate that the proposed augmented diffusion algorithm with bidirectional communication can achieve a faster convergence speed than that based on one-way communication with a lower memory, computation, and communication burden.

Bidirectional high-speed chaotic communication system based on an all-optical time-delay feedback loop

A bidirectional high-speed chaotic optical communication scheme with physical layer encryption is proposed and studied theoretically. The external cavity optical feedback method is analyzed. An erbium-doped fiber amplifier is used to represent the all-optical delay feedback loop of the traditional external cavity; it can overcome the shortcomings of the traditional method such as lower precision and high equipment volume requirements. The bidirectional communication scheme is discussed; it sets the encryption device at the transmitter, uses the correlation between the two encryption signals to decrypt, and cancels the decryption device at the receiver, which not only simplifies the experimental equipment but also solves the problem that the receiver cannot decrypt synchronously due to the channel damage in remote communication. Further, it is easily applied in production and life. Finally, the simulation results show that the bit error rate is <10 − 5, and the bidirectional transmission of 10-Gb / s information over an 85-km single-mode fiber is successfully realized.

Wideband complex-enhanced bidirectional phase chaotic secure communication with time-delay signature concealment.

A novel bandwidth-enhanced bidirectional phase chaotic secure communication system with time-delay signature (TDS) concealment is proposed and analyzed by numerical simulation. This bidirectional system based on two mutually coupled electro-optic (MCEO) phase feedback loops is driven by a common all-optical (AO) chaotic source. The AO driving source makes the amplitude and phase terms in the Ikeda-based MCEO equation chaotic. Two mutually coupled optoelectronic delayed feedback loops also greatly increase the complexity of the chaotic carrier. By replacing the semiconductor laser in the existing bidirectional communication scheme with an electro-optic feedback loop, the problems of narrow carrier bandwidth and poor synchronization performance can be compensated. Compared to the single MCEO system, the permutation entropy of the AO-MCEO cascaded system with a bit rate of 10 Gbit/s is improved by 0.13 to 0.98. The TDS of the AO-MCEO system is suppressed 35 times to less than 0.01 to be completely hidden when the EO gain is reduced by half to 2.75. The chaos effective bandwidth is increased by 5 GHz to 32.05 GHz, and the spectrum flatness is reduced by 0.33 dB/Hz to 0.82 dB/Hz. Meanwhile, the security is further enhanced by reducing the cross-correlation coefficient to 0.001 between the AO driving source and the electro-optical chaotic carrier. The results show that the proposed model has potential applications in bandwidth-enhanced bidirectional secure chaotic systems.

Key space enhancement of optical chaos secure communication: chirped FBG feedback semiconductor laser.

Optical chaos communication has advantages of high speed and long transmission distance. Unfortunately, the key space of the traditional transceiver, i.e. semiconductor laser with mirror feedback, is limited due to the time delay signature. In this paper, we propose and numerically demonstrate a key space enhancement by using semiconductor laser with optical feedback from a chirped fiber Bragg grating (FBG). The chirped FBG feedback can make feedback delay a key parameter by eliminating the time delay signature. Moreover, the grating dispersion and center frequency can also be used as new keys. As a result, the dimension of key space is increased. By taking a bidirectional communication scheme as an example, numerical results show that the key space is raised by 244 times as against mirror feedback with a data rate of 2.5 Gb/s and a coupling strength of 0.447. As the coupling strength decreases, the key space increases due to the fact that chaos synchronization becomes more sensitive to parameter mismatch.

Facilitating Human-Mobile Robot Communication via Haptic Feedback and Gesture Teleoperation

In this article, we present a bi-directional communication scheme that facilitates interaction between a person and a mobile robot that follows the person. A person-following robot can assist people in many applications including load carrying, elder care, and emotional support. However, commercially available personal robot systems usually have limited sensing and actuation capabilities. They are not expected to function perfectly in complex environments, and human intervention is required when the robot fails. We propose to use a holdable mechatronic device to reduce the user’s effort in communication and enable natural interaction during the intervention. Our design of the holdable device consists of two parts: a haptic interface that displays touch cues to convey the robot’s failure status via asymmetric vibrations, and a command interface for teleoperating the robot follower with hand gestures. We experimentally evaluated the device and the communication strategy in two sets of user studies with a controlled environment and a physical robot follower. Results show that with the proposed method, users are able to perform their tasks better, respond to robot failure events faster, and adjust walking speed according to the robot’s limitations. We also demonstrate that users can successfully teleoperate the robot to avoid obstacles when navigating in challenging environments.

3D NoC with Inductive-Coupling Links for Building-Block SiPs

A wireless 3D NoC architecture is described for building-block SiPs, in which the number of hardware components (or chips) in a package can be changed after chips have been fabricated. The architecture uses inductive-coupling links that can connect more than two examined dies without wire connections. Each chip has data transceivers for the uplink and downlink in order to communicate with its neighboring chips in the package. These chips form a vertical unidirectional ring network so as to fully exploit the flexibility of the wireless approach that enables us to add, remove, and swap the chips in the ring. To avoid protocol and structural deadlocks in the ring, we use bubble flow control, which does not rely on the conventional VC-based deadlock avoidance mechanism. In addition, we propose a bidirectional communication scheme to form a bidirectional ring network by using the inductive-coupling transceivers that can dynamically change the communication modes, such as TX, RX, and Idle modes. This paper illustrates the inductive-coupling transceiver circuits, which can carry high data transfer rates of up to 8 Gbps per channel, for the wireless 3D NoC. It also illustrates an implementation of a wireless 3D NoC that has on-chip routers and transceivers implemented with a 65 nm process in order to show the feasibility of our proposal. The vertical bubble flow control and conventional VC-based approach on the uni- and bidirectional ring networks are compared with the vertical broadcast bus in terms of throughput, hardware amount, and application performance using a full system multiprocessor simulator. The results show that the proposed bidirectional communication scheme efficiently improves application performance without adding any inductive-coupling transceivers. In addition, the proposed vertical bubble flow network outperforms the conventional VC-based approach by 7.9-12.5 percent with a 33.5 percent smaller router area for building-block SiPs connecting up to eight chips.

Integrating firewire peripheral interface with an ethernet custom network processor

Bandwidth demands on ubiquitous Ethernet have grown immensely, driven by the rapid expansion of real-time applications like audio/video streaming. In a related research, the authors designed a novel high-performance custom network processor chip using field programmable gate arrays (FPGAs). The main function of this chip (named SPEED) is to bypass the operating system processing of network protocol stack at the host computer by off-loading its networking functions to hardware. This simplification is not only required to fit in a hardware solution, but also it improves network performance. The novel chip utilizes the concept of Ethernet channels, where Ethernet frames are addressed in a multicast addressing scheme. In this article, we integrate the chip with a Firewire peripheral interface (FPI). A crucial function of the FPI design is to convert the IEEE 1394 isochronous traffic to the Ethernet frame format via two independent asynchronous write and read buffers. The FPI also manages the SPEED hardware interrupt signals in a bi-directional communication scheme. The goal of this research is to map isochronous Firewire packets into Ethernet frames by utilizing the SPEED Ethernet channel assignment capability. We used Verilog Hardware Description Language (HDL) to synthesize the FPI design. Since the FPI needs to support bi-directional communication, we also present a generic HDL model for bi-directional data sharing, which can be used in similar bi-directional applications. Initial performance measures show that the FPI consumes less that 0.15 W of power. Also we found that the synthesized design utilizes only 28% of the target chip resources. Hence it was possible to incorporate it with the SPEED design in the same FPGA chip. This low power consumption will lead to powering SPEED-FPI based network devices through the network cable and eliminate the process of regular electrical power outlet installations and maintenance. Thus, the SPEED-FPI system reduces the installation complexity, especially for large number of devices (e.g., surveillance cameras).